Merge branches 'clk-doc', 'clk-more-critical', 'clk-meson' and 'clk-basic-be' into...

[linux-2.6-microblaze.git] / drivers / clk / clk.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
 * Copyright (C) 2011-2012 Linaro Ltd <mturquette@linaro.org>
 *
 * Standard functionality for the common clock API.  See Documentation/driver-api/clk.rst
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/clk/clk-conf.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/err.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/pm_runtime.h>
#include <linux/sched.h>
#include <linux/clkdev.h>

#include "clk.h"

static DEFINE_SPINLOCK(enable_lock);
static DEFINE_MUTEX(prepare_lock);

static struct task_struct *prepare_owner;
static struct task_struct *enable_owner;

static int prepare_refcnt;
static int enable_refcnt;

static HLIST_HEAD(clk_root_list);
static HLIST_HEAD(clk_orphan_list);
static LIST_HEAD(clk_notifier_list);

/***    private data structures    ***/

struct clk_core {
        const char              *name;
        const struct clk_ops    *ops;
        struct clk_hw           *hw;
        struct module           *owner;
        struct device           *dev;
        struct clk_core         *parent;
        const char              **parent_names;
        struct clk_core         **parents;
        u8                      num_parents;
        u8                      new_parent_index;
        unsigned long           rate;
        unsigned long           req_rate;
        unsigned long           new_rate;
        struct clk_core         *new_parent;
        struct clk_core         *new_child;
        unsigned long           flags;
        bool                    orphan;
        bool                    rpm_enabled;
        unsigned int            enable_count;
        unsigned int            prepare_count;
        unsigned int            protect_count;
        unsigned long           min_rate;
        unsigned long           max_rate;
        unsigned long           accuracy;
        int                     phase;
        struct clk_duty         duty;
        struct hlist_head       children;
        struct hlist_node       child_node;
        struct hlist_head       clks;
        unsigned int            notifier_count;
#ifdef CONFIG_DEBUG_FS
        struct dentry           *dentry;
        struct hlist_node       debug_node;
#endif
        struct kref             ref;
};

#define CREATE_TRACE_POINTS
#include <trace/events/clk.h>

struct clk {
        struct clk_core *core;
        struct device *dev;
        const char *dev_id;
        const char *con_id;
        unsigned long min_rate;
        unsigned long max_rate;
        unsigned int exclusive_count;
        struct hlist_node clks_node;
};

/***           runtime pm          ***/
static int clk_pm_runtime_get(struct clk_core *core)
{
        int ret;

        if (!core->rpm_enabled)
                return 0;

        ret = pm_runtime_get_sync(core->dev);
        return ret < 0 ? ret : 0;
}

static void clk_pm_runtime_put(struct clk_core *core)
{
        if (!core->rpm_enabled)
                return;

        pm_runtime_put_sync(core->dev);
}

/***           locking             ***/
static void clk_prepare_lock(void)
{
        if (!mutex_trylock(&prepare_lock)) {
                if (prepare_owner == current) {
                        prepare_refcnt++;
                        return;
                }
                mutex_lock(&prepare_lock);
        }
        WARN_ON_ONCE(prepare_owner != NULL);
        WARN_ON_ONCE(prepare_refcnt != 0);
        prepare_owner = current;
        prepare_refcnt = 1;
}

static void clk_prepare_unlock(void)
{
        WARN_ON_ONCE(prepare_owner != current);
        WARN_ON_ONCE(prepare_refcnt == 0);

        if (--prepare_refcnt)
                return;
        prepare_owner = NULL;
        mutex_unlock(&prepare_lock);
}

static unsigned long clk_enable_lock(void)
        __acquires(enable_lock)
{
        unsigned long flags;

        /*
         * On UP systems, spin_trylock_irqsave() always returns true, even if
         * we already hold the lock. So, in that case, we rely only on
         * reference counting.
         */
        if (!IS_ENABLED(CONFIG_SMP) ||
            !spin_trylock_irqsave(&enable_lock, flags)) {
                if (enable_owner == current) {
                        enable_refcnt++;
                        __acquire(enable_lock);
                        if (!IS_ENABLED(CONFIG_SMP))
                                local_save_flags(flags);
                        return flags;
                }
                spin_lock_irqsave(&enable_lock, flags);
        }
        WARN_ON_ONCE(enable_owner != NULL);
        WARN_ON_ONCE(enable_refcnt != 0);
        enable_owner = current;
        enable_refcnt = 1;
        return flags;
}

static void clk_enable_unlock(unsigned long flags)
        __releases(enable_lock)
{
        WARN_ON_ONCE(enable_owner != current);
        WARN_ON_ONCE(enable_refcnt == 0);

        if (--enable_refcnt) {
                __release(enable_lock);
                return;
        }
        enable_owner = NULL;
        spin_unlock_irqrestore(&enable_lock, flags);
}

static bool clk_core_rate_is_protected(struct clk_core *core)
{
        return core->protect_count;
}

static bool clk_core_is_prepared(struct clk_core *core)
{
        bool ret = false;

        /*
         * .is_prepared is optional for clocks that can prepare
         * fall back to software usage counter if it is missing
         */
        if (!core->ops->is_prepared)
                return core->prepare_count;

        if (!clk_pm_runtime_get(core)) {
                ret = core->ops->is_prepared(core->hw);
                clk_pm_runtime_put(core);
        }

        return ret;
}

static bool clk_core_is_enabled(struct clk_core *core)
{
        bool ret = false;

        /*
         * .is_enabled is only mandatory for clocks that gate
         * fall back to software usage counter if .is_enabled is missing
         */
        if (!core->ops->is_enabled)
                return core->enable_count;

        /*
         * Check if clock controller's device is runtime active before
         * calling .is_enabled callback. If not, assume that clock is
         * disabled, because we might be called from atomic context, from
         * which pm_runtime_get() is not allowed.
         * This function is called mainly from clk_disable_unused_subtree,
         * which ensures proper runtime pm activation of controller before
         * taking enable spinlock, but the below check is needed if one tries
         * to call it from other places.
         */
        if (core->rpm_enabled) {
                pm_runtime_get_noresume(core->dev);
                if (!pm_runtime_active(core->dev)) {
                        ret = false;
                        goto done;
                }
        }

        ret = core->ops->is_enabled(core->hw);
done:
        if (core->rpm_enabled)
                pm_runtime_put(core->dev);

        return ret;
}

/***    helper functions   ***/

const char *__clk_get_name(const struct clk *clk)
{
        return !clk ? NULL : clk->core->name;
}
EXPORT_SYMBOL_GPL(__clk_get_name);

const char *clk_hw_get_name(const struct clk_hw *hw)
{
        return hw->core->name;
}
EXPORT_SYMBOL_GPL(clk_hw_get_name);

struct clk_hw *__clk_get_hw(struct clk *clk)
{
        return !clk ? NULL : clk->core->hw;
}
EXPORT_SYMBOL_GPL(__clk_get_hw);

unsigned int clk_hw_get_num_parents(const struct clk_hw *hw)
{
        return hw->core->num_parents;
}
EXPORT_SYMBOL_GPL(clk_hw_get_num_parents);

struct clk_hw *clk_hw_get_parent(const struct clk_hw *hw)
{
        return hw->core->parent ? hw->core->parent->hw : NULL;
}
EXPORT_SYMBOL_GPL(clk_hw_get_parent);

static struct clk_core *__clk_lookup_subtree(const char *name,
                                             struct clk_core *core)
{
        struct clk_core *child;
        struct clk_core *ret;

        if (!strcmp(core->name, name))
                return core;

        hlist_for_each_entry(child, &core->children, child_node) {
                ret = __clk_lookup_subtree(name, child);
                if (ret)
                        return ret;
        }

        return NULL;
}

static struct clk_core *clk_core_lookup(const char *name)
{
        struct clk_core *root_clk;
        struct clk_core *ret;

        if (!name)
                return NULL;

        /* search the 'proper' clk tree first */
        hlist_for_each_entry(root_clk, &clk_root_list, child_node) {
                ret = __clk_lookup_subtree(name, root_clk);
                if (ret)
                        return ret;
        }

        /* if not found, then search the orphan tree */
        hlist_for_each_entry(root_clk, &clk_orphan_list, child_node) {
                ret = __clk_lookup_subtree(name, root_clk);
                if (ret)
                        return ret;
        }

        return NULL;
}

static struct clk_core *clk_core_get_parent_by_index(struct clk_core *core,
                                                         u8 index)
{
        if (!core || index >= core->num_parents)
                return NULL;

        if (!core->parents[index])
                core->parents[index] =
                                clk_core_lookup(core->parent_names[index]);

        return core->parents[index];
}

struct clk_hw *
clk_hw_get_parent_by_index(const struct clk_hw *hw, unsigned int index)
{
        struct clk_core *parent;

        parent = clk_core_get_parent_by_index(hw->core, index);

        return !parent ? NULL : parent->hw;
}
EXPORT_SYMBOL_GPL(clk_hw_get_parent_by_index);

unsigned int __clk_get_enable_count(struct clk *clk)
{
        return !clk ? 0 : clk->core->enable_count;
}

static unsigned long clk_core_get_rate_nolock(struct clk_core *core)
{
        if (!core)
                return 0;

        if (!core->num_parents || core->parent)
                return core->rate;

        /*
         * Clk must have a parent because num_parents > 0 but the parent isn't
         * known yet. Best to return 0 as the rate of this clk until we can
         * properly recalc the rate based on the parent's rate.
         */
        return 0;
}

unsigned long clk_hw_get_rate(const struct clk_hw *hw)
{
        return clk_core_get_rate_nolock(hw->core);
}
EXPORT_SYMBOL_GPL(clk_hw_get_rate);

static unsigned long __clk_get_accuracy(struct clk_core *core)
{
        if (!core)
                return 0;

        return core->accuracy;
}

unsigned long __clk_get_flags(struct clk *clk)
{
        return !clk ? 0 : clk->core->flags;
}
EXPORT_SYMBOL_GPL(__clk_get_flags);

unsigned long clk_hw_get_flags(const struct clk_hw *hw)
{
        return hw->core->flags;
}
EXPORT_SYMBOL_GPL(clk_hw_get_flags);

bool clk_hw_is_prepared(const struct clk_hw *hw)
{
        return clk_core_is_prepared(hw->core);
}
EXPORT_SYMBOL_GPL(clk_hw_is_prepared);

bool clk_hw_rate_is_protected(const struct clk_hw *hw)
{
        return clk_core_rate_is_protected(hw->core);
}
EXPORT_SYMBOL_GPL(clk_hw_rate_is_protected);

bool clk_hw_is_enabled(const struct clk_hw *hw)
{
        return clk_core_is_enabled(hw->core);
}
EXPORT_SYMBOL_GPL(clk_hw_is_enabled);

bool __clk_is_enabled(struct clk *clk)
{
        if (!clk)
                return false;

        return clk_core_is_enabled(clk->core);
}
EXPORT_SYMBOL_GPL(__clk_is_enabled);

static bool mux_is_better_rate(unsigned long rate, unsigned long now,
                           unsigned long best, unsigned long flags)
{
        if (flags & CLK_MUX_ROUND_CLOSEST)
                return abs(now - rate) < abs(best - rate);

        return now <= rate && now > best;
}

int clk_mux_determine_rate_flags(struct clk_hw *hw,
                                 struct clk_rate_request *req,
                                 unsigned long flags)
{
        struct clk_core *core = hw->core, *parent, *best_parent = NULL;
        int i, num_parents, ret;
        unsigned long best = 0;
        struct clk_rate_request parent_req = *req;

        /* if NO_REPARENT flag set, pass through to current parent */
        if (core->flags & CLK_SET_RATE_NO_REPARENT) {
                parent = core->parent;
                if (core->flags & CLK_SET_RATE_PARENT) {
                        ret = __clk_determine_rate(parent ? parent->hw : NULL,
                                                   &parent_req);
                        if (ret)
                                return ret;

                        best = parent_req.rate;
                } else if (parent) {
                        best = clk_core_get_rate_nolock(parent);
                } else {
                        best = clk_core_get_rate_nolock(core);
                }

                goto out;
        }

        /* find the parent that can provide the fastest rate <= rate */
        num_parents = core->num_parents;
        for (i = 0; i < num_parents; i++) {
                parent = clk_core_get_parent_by_index(core, i);
                if (!parent)
                        continue;

                if (core->flags & CLK_SET_RATE_PARENT) {
                        parent_req = *req;
                        ret = __clk_determine_rate(parent->hw, &parent_req);
                        if (ret)
                                continue;
                } else {
                        parent_req.rate = clk_core_get_rate_nolock(parent);
                }

                if (mux_is_better_rate(req->rate, parent_req.rate,
                                       best, flags)) {
                        best_parent = parent;
                        best = parent_req.rate;
                }
        }

        if (!best_parent)
                return -EINVAL;

out:
        if (best_parent)
                req->best_parent_hw = best_parent->hw;
        req->best_parent_rate = best;
        req->rate = best;

        return 0;
}
EXPORT_SYMBOL_GPL(clk_mux_determine_rate_flags);

struct clk *__clk_lookup(const char *name)
{
        struct clk_core *core = clk_core_lookup(name);

        return !core ? NULL : core->hw->clk;
}

static void clk_core_get_boundaries(struct clk_core *core,
                                    unsigned long *min_rate,
                                    unsigned long *max_rate)
{
        struct clk *clk_user;

        *min_rate = core->min_rate;
        *max_rate = core->max_rate;

        hlist_for_each_entry(clk_user, &core->clks, clks_node)
                *min_rate = max(*min_rate, clk_user->min_rate);

        hlist_for_each_entry(clk_user, &core->clks, clks_node)
                *max_rate = min(*max_rate, clk_user->max_rate);
}

void clk_hw_set_rate_range(struct clk_hw *hw, unsigned long min_rate,
                           unsigned long max_rate)
{
        hw->core->min_rate = min_rate;
        hw->core->max_rate = max_rate;
}
EXPORT_SYMBOL_GPL(clk_hw_set_rate_range);

/*
 * __clk_mux_determine_rate - clk_ops::determine_rate implementation for a mux type clk
 * @hw: mux type clk to determine rate on
 * @req: rate request, also used to return preferred parent and frequencies
 *
 * Helper for finding best parent to provide a given frequency. This can be used
 * directly as a determine_rate callback (e.g. for a mux), or from a more
 * complex clock that may combine a mux with other operations.
 *
 * Returns: 0 on success, -EERROR value on error
 */
int __clk_mux_determine_rate(struct clk_hw *hw,
                             struct clk_rate_request *req)
{
        return clk_mux_determine_rate_flags(hw, req, 0);
}
EXPORT_SYMBOL_GPL(__clk_mux_determine_rate);

int __clk_mux_determine_rate_closest(struct clk_hw *hw,
                                     struct clk_rate_request *req)
{
        return clk_mux_determine_rate_flags(hw, req, CLK_MUX_ROUND_CLOSEST);
}
EXPORT_SYMBOL_GPL(__clk_mux_determine_rate_closest);

/***        clk api        ***/

static void clk_core_rate_unprotect(struct clk_core *core)
{
        lockdep_assert_held(&prepare_lock);

        if (!core)
                return;

        if (WARN(core->protect_count == 0,
            "%s already unprotected\n", core->name))
                return;

        if (--core->protect_count > 0)
                return;

        clk_core_rate_unprotect(core->parent);
}

static int clk_core_rate_nuke_protect(struct clk_core *core)
{
        int ret;

        lockdep_assert_held(&prepare_lock);

        if (!core)
                return -EINVAL;

        if (core->protect_count == 0)
                return 0;

        ret = core->protect_count;
        core->protect_count = 1;
        clk_core_rate_unprotect(core);

        return ret;
}

/**
 * clk_rate_exclusive_put - release exclusivity over clock rate control
 * @clk: the clk over which the exclusivity is released
 *
 * clk_rate_exclusive_put() completes a critical section during which a clock
 * consumer cannot tolerate any other consumer making any operation on the
 * clock which could result in a rate change or rate glitch. Exclusive clocks
 * cannot have their rate changed, either directly or indirectly due to changes
 * further up the parent chain of clocks. As a result, clocks up parent chain
 * also get under exclusive control of the calling consumer.
 *
 * If exlusivity is claimed more than once on clock, even by the same consumer,
 * the rate effectively gets locked as exclusivity can't be preempted.
 *
 * Calls to clk_rate_exclusive_put() must be balanced with calls to
 * clk_rate_exclusive_get(). Calls to this function may sleep, and do not return
 * error status.
 */
void clk_rate_exclusive_put(struct clk *clk)
{
        if (!clk)
                return;

        clk_prepare_lock();

        /*
         * if there is something wrong with this consumer protect count, stop
         * here before messing with the provider
         */
        if (WARN_ON(clk->exclusive_count <= 0))
                goto out;

        clk_core_rate_unprotect(clk->core);
        clk->exclusive_count--;
out:
        clk_prepare_unlock();
}
EXPORT_SYMBOL_GPL(clk_rate_exclusive_put);

static void clk_core_rate_protect(struct clk_core *core)
{
        lockdep_assert_held(&prepare_lock);

        if (!core)
                return;

        if (core->protect_count == 0)
                clk_core_rate_protect(core->parent);

        core->protect_count++;
}

static void clk_core_rate_restore_protect(struct clk_core *core, int count)
{
        lockdep_assert_held(&prepare_lock);

        if (!core)
                return;

        if (count == 0)
                return;

        clk_core_rate_protect(core);
        core->protect_count = count;
}

/**
 * clk_rate_exclusive_get - get exclusivity over the clk rate control
 * @clk: the clk over which the exclusity of rate control is requested
 *
 * clk_rate_exlusive_get() begins a critical section during which a clock
 * consumer cannot tolerate any other consumer making any operation on the
 * clock which could result in a rate change or rate glitch. Exclusive clocks
 * cannot have their rate changed, either directly or indirectly due to changes
 * further up the parent chain of clocks. As a result, clocks up parent chain
 * also get under exclusive control of the calling consumer.
 *
 * If exlusivity is claimed more than once on clock, even by the same consumer,
 * the rate effectively gets locked as exclusivity can't be preempted.
 *
 * Calls to clk_rate_exclusive_get() should be balanced with calls to
 * clk_rate_exclusive_put(). Calls to this function may sleep.
 * Returns 0 on success, -EERROR otherwise
 */
int clk_rate_exclusive_get(struct clk *clk)
{
        if (!clk)
                return 0;

        clk_prepare_lock();
        clk_core_rate_protect(clk->core);
        clk->exclusive_count++;
        clk_prepare_unlock();

        return 0;
}
EXPORT_SYMBOL_GPL(clk_rate_exclusive_get);

static void clk_core_unprepare(struct clk_core *core)
{
        lockdep_assert_held(&prepare_lock);

        if (!core)
                return;

        if (WARN(core->prepare_count == 0,
            "%s already unprepared\n", core->name))
                return;

        if (WARN(core->prepare_count == 1 && core->flags & CLK_IS_CRITICAL,
            "Unpreparing critical %s\n", core->name))
                return;

        if (core->flags & CLK_SET_RATE_GATE)
                clk_core_rate_unprotect(core);

        if (--core->prepare_count > 0)
                return;

        WARN(core->enable_count > 0, "Unpreparing enabled %s\n", core->name);

        trace_clk_unprepare(core);

        if (core->ops->unprepare)
                core->ops->unprepare(core->hw);

        clk_pm_runtime_put(core);

        trace_clk_unprepare_complete(core);
        clk_core_unprepare(core->parent);
}

static void clk_core_unprepare_lock(struct clk_core *core)
{
        clk_prepare_lock();
        clk_core_unprepare(core);
        clk_prepare_unlock();
}

/**
 * clk_unprepare - undo preparation of a clock source
 * @clk: the clk being unprepared
 *
 * clk_unprepare may sleep, which differentiates it from clk_disable.  In a
 * simple case, clk_unprepare can be used instead of clk_disable to gate a clk
 * if the operation may sleep.  One example is a clk which is accessed over
 * I2c.  In the complex case a clk gate operation may require a fast and a slow
 * part.  It is this reason that clk_unprepare and clk_disable are not mutually
 * exclusive.  In fact clk_disable must be called before clk_unprepare.
 */
void clk_unprepare(struct clk *clk)
{
        if (IS_ERR_OR_NULL(clk))
                return;

        clk_core_unprepare_lock(clk->core);
}
EXPORT_SYMBOL_GPL(clk_unprepare);

static int clk_core_prepare(struct clk_core *core)
{
        int ret = 0;

        lockdep_assert_held(&prepare_lock);

        if (!core)
                return 0;

        if (core->prepare_count == 0) {
                ret = clk_pm_runtime_get(core);
                if (ret)
                        return ret;

                ret = clk_core_prepare(core->parent);
                if (ret)
                        goto runtime_put;

                trace_clk_prepare(core);

                if (core->ops->prepare)
                        ret = core->ops->prepare(core->hw);

                trace_clk_prepare_complete(core);

                if (ret)
                        goto unprepare;
        }

        core->prepare_count++;

        /*
         * CLK_SET_RATE_GATE is a special case of clock protection
         * Instead of a consumer claiming exclusive rate control, it is
         * actually the provider which prevents any consumer from making any
         * operation which could result in a rate change or rate glitch while
         * the clock is prepared.
         */
        if (core->flags & CLK_SET_RATE_GATE)
                clk_core_rate_protect(core);

        return 0;
unprepare:
        clk_core_unprepare(core->parent);
runtime_put:
        clk_pm_runtime_put(core);
        return ret;
}

static int clk_core_prepare_lock(struct clk_core *core)
{
        int ret;

        clk_prepare_lock();
        ret = clk_core_prepare(core);
        clk_prepare_unlock();

        return ret;
}

/**
 * clk_prepare - prepare a clock source
 * @clk: the clk being prepared
 *
 * clk_prepare may sleep, which differentiates it from clk_enable.  In a simple
 * case, clk_prepare can be used instead of clk_enable to ungate a clk if the
 * operation may sleep.  One example is a clk which is accessed over I2c.  In
 * the complex case a clk ungate operation may require a fast and a slow part.
 * It is this reason that clk_prepare and clk_enable are not mutually
 * exclusive.  In fact clk_prepare must be called before clk_enable.
 * Returns 0 on success, -EERROR otherwise.
 */
int clk_prepare(struct clk *clk)
{
        if (!clk)
                return 0;

        return clk_core_prepare_lock(clk->core);
}
EXPORT_SYMBOL_GPL(clk_prepare);

static void clk_core_disable(struct clk_core *core)
{
        lockdep_assert_held(&enable_lock);

        if (!core)
                return;

        if (WARN(core->enable_count == 0, "%s already disabled\n", core->name))
                return;

        if (WARN(core->enable_count == 1 && core->flags & CLK_IS_CRITICAL,
            "Disabling critical %s\n", core->name))
                return;

        if (--core->enable_count > 0)
                return;

        trace_clk_disable_rcuidle(core);

        if (core->ops->disable)
                core->ops->disable(core->hw);

        trace_clk_disable_complete_rcuidle(core);

        clk_core_disable(core->parent);
}

static void clk_core_disable_lock(struct clk_core *core)
{
        unsigned long flags;

        flags = clk_enable_lock();
        clk_core_disable(core);
        clk_enable_unlock(flags);
}

/**
 * clk_disable - gate a clock
 * @clk: the clk being gated
 *
 * clk_disable must not sleep, which differentiates it from clk_unprepare.  In
 * a simple case, clk_disable can be used instead of clk_unprepare to gate a
 * clk if the operation is fast and will never sleep.  One example is a
 * SoC-internal clk which is controlled via simple register writes.  In the
 * complex case a clk gate operation may require a fast and a slow part.  It is
 * this reason that clk_unprepare and clk_disable are not mutually exclusive.
 * In fact clk_disable must be called before clk_unprepare.
 */
void clk_disable(struct clk *clk)
{
        if (IS_ERR_OR_NULL(clk))
                return;

        clk_core_disable_lock(clk->core);
}
EXPORT_SYMBOL_GPL(clk_disable);

static int clk_core_enable(struct clk_core *core)
{
        int ret = 0;

        lockdep_assert_held(&enable_lock);

        if (!core)
                return 0;

        if (WARN(core->prepare_count == 0,
            "Enabling unprepared %s\n", core->name))
                return -ESHUTDOWN;

        if (core->enable_count == 0) {
                ret = clk_core_enable(core->parent);

                if (ret)
                        return ret;

                trace_clk_enable_rcuidle(core);

                if (core->ops->enable)
                        ret = core->ops->enable(core->hw);

                trace_clk_enable_complete_rcuidle(core);

                if (ret) {
                        clk_core_disable(core->parent);
                        return ret;
                }
        }

        core->enable_count++;
        return 0;
}

static int clk_core_enable_lock(struct clk_core *core)
{
        unsigned long flags;
        int ret;

        flags = clk_enable_lock();
        ret = clk_core_enable(core);
        clk_enable_unlock(flags);

        return ret;
}

/**
 * clk_gate_restore_context - restore context for poweroff
 * @hw: the clk_hw pointer of clock whose state is to be restored
 *
 * The clock gate restore context function enables or disables
 * the gate clocks based on the enable_count. This is done in cases
 * where the clock context is lost and based on the enable_count
 * the clock either needs to be enabled/disabled. This
 * helps restore the state of gate clocks.
 */
void clk_gate_restore_context(struct clk_hw *hw)
{
        struct clk_core *core = hw->core;

        if (core->enable_count)
                core->ops->enable(hw);
        else
                core->ops->disable(hw);
}
EXPORT_SYMBOL_GPL(clk_gate_restore_context);

static int clk_core_save_context(struct clk_core *core)
{
        struct clk_core *child;
        int ret = 0;

        hlist_for_each_entry(child, &core->children, child_node) {
                ret = clk_core_save_context(child);
                if (ret < 0)
                        return ret;
        }

        if (core->ops && core->ops->save_context)
                ret = core->ops->save_context(core->hw);

        return ret;
}

static void clk_core_restore_context(struct clk_core *core)
{
        struct clk_core *child;

        if (core->ops && core->ops->restore_context)
                core->ops->restore_context(core->hw);

        hlist_for_each_entry(child, &core->children, child_node)
                clk_core_restore_context(child);
}

/**
 * clk_save_context - save clock context for poweroff
 *
 * Saves the context of the clock register for powerstates in which the
 * contents of the registers will be lost. Occurs deep within the suspend
 * code.  Returns 0 on success.
 */
int clk_save_context(void)
{
        struct clk_core *clk;
        int ret;

        hlist_for_each_entry(clk, &clk_root_list, child_node) {
                ret = clk_core_save_context(clk);
                if (ret < 0)
                        return ret;
        }

        hlist_for_each_entry(clk, &clk_orphan_list, child_node) {
                ret = clk_core_save_context(clk);
                if (ret < 0)
                        return ret;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(clk_save_context);

/**
 * clk_restore_context - restore clock context after poweroff
 *
 * Restore the saved clock context upon resume.
 *
 */
void clk_restore_context(void)
{
        struct clk_core *core;

        hlist_for_each_entry(core, &clk_root_list, child_node)
                clk_core_restore_context(core);

        hlist_for_each_entry(core, &clk_orphan_list, child_node)
                clk_core_restore_context(core);
}
EXPORT_SYMBOL_GPL(clk_restore_context);

/**
 * clk_enable - ungate a clock
 * @clk: the clk being ungated
 *
 * clk_enable must not sleep, which differentiates it from clk_prepare.  In a
 * simple case, clk_enable can be used instead of clk_prepare to ungate a clk
 * if the operation will never sleep.  One example is a SoC-internal clk which
 * is controlled via simple register writes.  In the complex case a clk ungate
 * operation may require a fast and a slow part.  It is this reason that
 * clk_enable and clk_prepare are not mutually exclusive.  In fact clk_prepare
 * must be called before clk_enable.  Returns 0 on success, -EERROR
 * otherwise.
 */
int clk_enable(struct clk *clk)
{
        if (!clk)
                return 0;

        return clk_core_enable_lock(clk->core);
}
EXPORT_SYMBOL_GPL(clk_enable);

static int clk_core_prepare_enable(struct clk_core *core)
{
        int ret;

        ret = clk_core_prepare_lock(core);
        if (ret)
                return ret;

        ret = clk_core_enable_lock(core);
        if (ret)
                clk_core_unprepare_lock(core);

        return ret;
}

static void clk_core_disable_unprepare(struct clk_core *core)
{
        clk_core_disable_lock(core);
        clk_core_unprepare_lock(core);
}

static void clk_unprepare_unused_subtree(struct clk_core *core)
{
        struct clk_core *child;

        lockdep_assert_held(&prepare_lock);

        hlist_for_each_entry(child, &core->children, child_node)
                clk_unprepare_unused_subtree(child);

        if (core->prepare_count)
                return;

        if (core->flags & CLK_IGNORE_UNUSED)
                return;

        if (clk_pm_runtime_get(core))
                return;

        if (clk_core_is_prepared(core)) {
                trace_clk_unprepare(core);
                if (core->ops->unprepare_unused)
                        core->ops->unprepare_unused(core->hw);
                else if (core->ops->unprepare)
                        core->ops->unprepare(core->hw);
                trace_clk_unprepare_complete(core);
        }

        clk_pm_runtime_put(core);
}

static void clk_disable_unused_subtree(struct clk_core *core)
{
        struct clk_core *child;
        unsigned long flags;

        lockdep_assert_held(&prepare_lock);

        hlist_for_each_entry(child, &core->children, child_node)
                clk_disable_unused_subtree(child);

        if (core->flags & CLK_OPS_PARENT_ENABLE)
                clk_core_prepare_enable(core->parent);

        if (clk_pm_runtime_get(core))
                goto unprepare_out;

        flags = clk_enable_lock();

        if (core->enable_count)
                goto unlock_out;

        if (core->flags & CLK_IGNORE_UNUSED)
                goto unlock_out;

        /*
         * some gate clocks have special needs during the disable-unused
         * sequence.  call .disable_unused if available, otherwise fall
         * back to .disable
         */
        if (clk_core_is_enabled(core)) {
                trace_clk_disable(core);
                if (core->ops->disable_unused)
                        core->ops->disable_unused(core->hw);
                else if (core->ops->disable)
                        core->ops->disable(core->hw);
                trace_clk_disable_complete(core);
        }

unlock_out:
        clk_enable_unlock(flags);
        clk_pm_runtime_put(core);
unprepare_out:
        if (core->flags & CLK_OPS_PARENT_ENABLE)
                clk_core_disable_unprepare(core->parent);
}

static bool clk_ignore_unused;
static int __init clk_ignore_unused_setup(char *__unused)
{
        clk_ignore_unused = true;
        return 1;
}
__setup("clk_ignore_unused", clk_ignore_unused_setup);

static int clk_disable_unused(void)
{
        struct clk_core *core;

        if (clk_ignore_unused) {
                pr_warn("clk: Not disabling unused clocks\n");
                return 0;
        }

        clk_prepare_lock();

        hlist_for_each_entry(core, &clk_root_list, child_node)
                clk_disable_unused_subtree(core);

        hlist_for_each_entry(core, &clk_orphan_list, child_node)
                clk_disable_unused_subtree(core);

        hlist_for_each_entry(core, &clk_root_list, child_node)
                clk_unprepare_unused_subtree(core);

        hlist_for_each_entry(core, &clk_orphan_list, child_node)
                clk_unprepare_unused_subtree(core);

        clk_prepare_unlock();

        return 0;
}
late_initcall_sync(clk_disable_unused);

static int clk_core_determine_round_nolock(struct clk_core *core,
                                           struct clk_rate_request *req)
{
        long rate;

        lockdep_assert_held(&prepare_lock);

        if (!core)
                return 0;

        /*
         * At this point, core protection will be disabled if
         * - if the provider is not protected at all
         * - if the calling consumer is the only one which has exclusivity
         *   over the provider
         */
        if (clk_core_rate_is_protected(core)) {
                req->rate = core->rate;
        } else if (core->ops->determine_rate) {
                return core->ops->determine_rate(core->hw, req);
        } else if (core->ops->round_rate) {
                rate = core->ops->round_rate(core->hw, req->rate,
                                             &req->best_parent_rate);
                if (rate < 0)
                        return rate;

                req->rate = rate;
        } else {
                return -EINVAL;
        }

        return 0;
}

static void clk_core_init_rate_req(struct clk_core * const core,
                                   struct clk_rate_request *req)
{
        struct clk_core *parent;

        if (WARN_ON(!core || !req))
                return;

        parent = core->parent;
        if (parent) {
                req->best_parent_hw = parent->hw;
                req->best_parent_rate = parent->rate;
        } else {
                req->best_parent_hw = NULL;
                req->best_parent_rate = 0;
        }
}

static bool clk_core_can_round(struct clk_core * const core)
{
        if (core->ops->determine_rate || core->ops->round_rate)
                return true;

        return false;
}

static int clk_core_round_rate_nolock(struct clk_core *core,
                                      struct clk_rate_request *req)
{
        lockdep_assert_held(&prepare_lock);

        if (!core) {
                req->rate = 0;
                return 0;
        }

        clk_core_init_rate_req(core, req);

        if (clk_core_can_round(core))
                return clk_core_determine_round_nolock(core, req);
        else if (core->flags & CLK_SET_RATE_PARENT)
                return clk_core_round_rate_nolock(core->parent, req);

        req->rate = core->rate;
        return 0;
}

/**
 * __clk_determine_rate - get the closest rate actually supported by a clock
 * @hw: determine the rate of this clock
 * @req: target rate request
 *
 * Useful for clk_ops such as .set_rate and .determine_rate.
 */
int __clk_determine_rate(struct clk_hw *hw, struct clk_rate_request *req)
{
        if (!hw) {
                req->rate = 0;
                return 0;
        }

        return clk_core_round_rate_nolock(hw->core, req);
}
EXPORT_SYMBOL_GPL(__clk_determine_rate);

unsigned long clk_hw_round_rate(struct clk_hw *hw, unsigned long rate)
{
        int ret;
        struct clk_rate_request req;

        clk_core_get_boundaries(hw->core, &req.min_rate, &req.max_rate);
        req.rate = rate;

        ret = clk_core_round_rate_nolock(hw->core, &req);
        if (ret)
                return 0;

        return req.rate;
}
EXPORT_SYMBOL_GPL(clk_hw_round_rate);

/**
 * clk_round_rate - round the given rate for a clk
 * @clk: the clk for which we are rounding a rate
 * @rate: the rate which is to be rounded
 *
 * Takes in a rate as input and rounds it to a rate that the clk can actually
 * use which is then returned.  If clk doesn't support round_rate operation
 * then the parent rate is returned.
 */
long clk_round_rate(struct clk *clk, unsigned long rate)
{
        struct clk_rate_request req;
        int ret;

        if (!clk)
                return 0;

        clk_prepare_lock();

        if (clk->exclusive_count)
                clk_core_rate_unprotect(clk->core);

        clk_core_get_boundaries(clk->core, &req.min_rate, &req.max_rate);
        req.rate = rate;

        ret = clk_core_round_rate_nolock(clk->core, &req);

        if (clk->exclusive_count)
                clk_core_rate_protect(clk->core);

        clk_prepare_unlock();

        if (ret)
                return ret;

        return req.rate;
}
EXPORT_SYMBOL_GPL(clk_round_rate);

/**
 * __clk_notify - call clk notifier chain
 * @core: clk that is changing rate
 * @msg: clk notifier type (see include/linux/clk.h)
 * @old_rate: old clk rate
 * @new_rate: new clk rate
 *
 * Triggers a notifier call chain on the clk rate-change notification
 * for 'clk'.  Passes a pointer to the struct clk and the previous
 * and current rates to the notifier callback.  Intended to be called by
 * internal clock code only.  Returns NOTIFY_DONE from the last driver
 * called if all went well, or NOTIFY_STOP or NOTIFY_BAD immediately if
 * a driver returns that.
 */
static int __clk_notify(struct clk_core *core, unsigned long msg,
                unsigned long old_rate, unsigned long new_rate)
{
        struct clk_notifier *cn;
        struct clk_notifier_data cnd;
        int ret = NOTIFY_DONE;

        cnd.old_rate = old_rate;
        cnd.new_rate = new_rate;

        list_for_each_entry(cn, &clk_notifier_list, node) {
                if (cn->clk->core == core) {
                        cnd.clk = cn->clk;
                        ret = srcu_notifier_call_chain(&cn->notifier_head, msg,
                                        &cnd);
                        if (ret & NOTIFY_STOP_MASK)
                                return ret;
                }
        }

        return ret;
}

/**
 * __clk_recalc_accuracies
 * @core: first clk in the subtree
 *
 * Walks the subtree of clks starting with clk and recalculates accuracies as
 * it goes.  Note that if a clk does not implement the .recalc_accuracy
 * callback then it is assumed that the clock will take on the accuracy of its
 * parent.
 */
static void __clk_recalc_accuracies(struct clk_core *core)
{
        unsigned long parent_accuracy = 0;
        struct clk_core *child;

        lockdep_assert_held(&prepare_lock);

        if (core->parent)
                parent_accuracy = core->parent->accuracy;

        if (core->ops->recalc_accuracy)
                core->accuracy = core->ops->recalc_accuracy(core->hw,
                                                          parent_accuracy);
        else
                core->accuracy = parent_accuracy;

        hlist_for_each_entry(child, &core->children, child_node)
                __clk_recalc_accuracies(child);
}

static long clk_core_get_accuracy(struct clk_core *core)
{
        unsigned long accuracy;

        clk_prepare_lock();
        if (core && (core->flags & CLK_GET_ACCURACY_NOCACHE))
                __clk_recalc_accuracies(core);

        accuracy = __clk_get_accuracy(core);
        clk_prepare_unlock();

        return accuracy;
}

/**
 * clk_get_accuracy - return the accuracy of clk
 * @clk: the clk whose accuracy is being returned
 *
 * Simply returns the cached accuracy of the clk, unless
 * CLK_GET_ACCURACY_NOCACHE flag is set, which means a recalc_rate will be
 * issued.
 * If clk is NULL then returns 0.
 */
long clk_get_accuracy(struct clk *clk)
{
        if (!clk)
                return 0;

        return clk_core_get_accuracy(clk->core);
}
EXPORT_SYMBOL_GPL(clk_get_accuracy);

static unsigned long clk_recalc(struct clk_core *core,
                                unsigned long parent_rate)
{
        unsigned long rate = parent_rate;

        if (core->ops->recalc_rate && !clk_pm_runtime_get(core)) {
                rate = core->ops->recalc_rate(core->hw, parent_rate);
                clk_pm_runtime_put(core);
        }
        return rate;
}

/**
 * __clk_recalc_rates
 * @core: first clk in the subtree
 * @msg: notification type (see include/linux/clk.h)
 *
 * Walks the subtree of clks starting with clk and recalculates rates as it
 * goes.  Note that if a clk does not implement the .recalc_rate callback then
 * it is assumed that the clock will take on the rate of its parent.
 *
 * clk_recalc_rates also propagates the POST_RATE_CHANGE notification,
 * if necessary.
 */
static void __clk_recalc_rates(struct clk_core *core, unsigned long msg)
{
        unsigned long old_rate;
        unsigned long parent_rate = 0;
        struct clk_core *child;

        lockdep_assert_held(&prepare_lock);

        old_rate = core->rate;

        if (core->parent)
                parent_rate = core->parent->rate;

        core->rate = clk_recalc(core, parent_rate);

        /*
         * ignore NOTIFY_STOP and NOTIFY_BAD return values for POST_RATE_CHANGE
         * & ABORT_RATE_CHANGE notifiers
         */
        if (core->notifier_count && msg)
                __clk_notify(core, msg, old_rate, core->rate);

        hlist_for_each_entry(child, &core->children, child_node)
                __clk_recalc_rates(child, msg);
}

static unsigned long clk_core_get_rate(struct clk_core *core)
{
        unsigned long rate;

        clk_prepare_lock();

        if (core && (core->flags & CLK_GET_RATE_NOCACHE))
                __clk_recalc_rates(core, 0);

        rate = clk_core_get_rate_nolock(core);
        clk_prepare_unlock();

        return rate;
}

/**
 * clk_get_rate - return the rate of clk
 * @clk: the clk whose rate is being returned
 *
 * Simply returns the cached rate of the clk, unless CLK_GET_RATE_NOCACHE flag
 * is set, which means a recalc_rate will be issued.
 * If clk is NULL then returns 0.
 */
unsigned long clk_get_rate(struct clk *clk)
{
        if (!clk)
                return 0;

        return clk_core_get_rate(clk->core);
}
EXPORT_SYMBOL_GPL(clk_get_rate);

static int clk_fetch_parent_index(struct clk_core *core,
                                  struct clk_core *parent)
{
        int i;

        if (!parent)
                return -EINVAL;

        for (i = 0; i < core->num_parents; i++) {
                if (core->parents[i] == parent)
                        return i;

                if (core->parents[i])
                        continue;

                /* Fallback to comparing globally unique names */
                if (!strcmp(parent->name, core->parent_names[i])) {
                        core->parents[i] = parent;
                        return i;
                }
        }

        return -EINVAL;
}

/*
 * Update the orphan status of @core and all its children.
 */
static void clk_core_update_orphan_status(struct clk_core *core, bool is_orphan)
{
        struct clk_core *child;

        core->orphan = is_orphan;

        hlist_for_each_entry(child, &core->children, child_node)
                clk_core_update_orphan_status(child, is_orphan);
}

static void clk_reparent(struct clk_core *core, struct clk_core *new_parent)
{
        bool was_orphan = core->orphan;

        hlist_del(&core->child_node);

        if (new_parent) {
                bool becomes_orphan = new_parent->orphan;

                /* avoid duplicate POST_RATE_CHANGE notifications */
                if (new_parent->new_child == core)
                        new_parent->new_child = NULL;

                hlist_add_head(&core->child_node, &new_parent->children);

                if (was_orphan != becomes_orphan)
                        clk_core_update_orphan_status(core, becomes_orphan);
        } else {
                hlist_add_head(&core->child_node, &clk_orphan_list);
                if (!was_orphan)
                        clk_core_update_orphan_status(core, true);
        }

        core->parent = new_parent;
}

static struct clk_core *__clk_set_parent_before(struct clk_core *core,
                                           struct clk_core *parent)
{
        unsigned long flags;
        struct clk_core *old_parent = core->parent;

        /*
         * 1. enable parents for CLK_OPS_PARENT_ENABLE clock
         *
         * 2. Migrate prepare state between parents and prevent race with
         * clk_enable().
         *
         * If the clock is not prepared, then a race with
         * clk_enable/disable() is impossible since we already have the
         * prepare lock (future calls to clk_enable() need to be preceded by
         * a clk_prepare()).
         *
         * If the clock is prepared, migrate the prepared state to the new
         * parent and also protect against a race with clk_enable() by
         * forcing the clock and the new parent on.  This ensures that all
         * future calls to clk_enable() are practically NOPs with respect to
         * hardware and software states.
         *
         * See also: Comment for clk_set_parent() below.
         */

        /* enable old_parent & parent if CLK_OPS_PARENT_ENABLE is set */
        if (core->flags & CLK_OPS_PARENT_ENABLE) {
                clk_core_prepare_enable(old_parent);
                clk_core_prepare_enable(parent);
        }

        /* migrate prepare count if > 0 */
        if (core->prepare_count) {
                clk_core_prepare_enable(parent);
                clk_core_enable_lock(core);
        }

        /* update the clk tree topology */
        flags = clk_enable_lock();
        clk_reparent(core, parent);
        clk_enable_unlock(flags);

        return old_parent;
}

static void __clk_set_parent_after(struct clk_core *core,
                                   struct clk_core *parent,
                                   struct clk_core *old_parent)
{
        /*
         * Finish the migration of prepare state and undo the changes done
         * for preventing a race with clk_enable().
         */
        if (core->prepare_count) {
                clk_core_disable_lock(core);
                clk_core_disable_unprepare(old_parent);
        }

        /* re-balance ref counting if CLK_OPS_PARENT_ENABLE is set */
        if (core->flags & CLK_OPS_PARENT_ENABLE) {
                clk_core_disable_unprepare(parent);
                clk_core_disable_unprepare(old_parent);
        }
}

static int __clk_set_parent(struct clk_core *core, struct clk_core *parent,
                            u8 p_index)
{
        unsigned long flags;
        int ret = 0;
        struct clk_core *old_parent;

        old_parent = __clk_set_parent_before(core, parent);

        trace_clk_set_parent(core, parent);

        /* change clock input source */
        if (parent && core->ops->set_parent)
                ret = core->ops->set_parent(core->hw, p_index);

        trace_clk_set_parent_complete(core, parent);

        if (ret) {
                flags = clk_enable_lock();
                clk_reparent(core, old_parent);
                clk_enable_unlock(flags);
                __clk_set_parent_after(core, old_parent, parent);

                return ret;
        }

        __clk_set_parent_after(core, parent, old_parent);

        return 0;
}

/**
 * __clk_speculate_rates
 * @core: first clk in the subtree
 * @parent_rate: the "future" rate of clk's parent
 *
 * Walks the subtree of clks starting with clk, speculating rates as it
 * goes and firing off PRE_RATE_CHANGE notifications as necessary.
 *
 * Unlike clk_recalc_rates, clk_speculate_rates exists only for sending
 * pre-rate change notifications and returns early if no clks in the
 * subtree have subscribed to the notifications.  Note that if a clk does not
 * implement the .recalc_rate callback then it is assumed that the clock will
 * take on the rate of its parent.
 */
static int __clk_speculate_rates(struct clk_core *core,
                                 unsigned long parent_rate)
{
        struct clk_core *child;
        unsigned long new_rate;
        int ret = NOTIFY_DONE;

        lockdep_assert_held(&prepare_lock);

        new_rate = clk_recalc(core, parent_rate);

        /* abort rate change if a driver returns NOTIFY_BAD or NOTIFY_STOP */
        if (core->notifier_count)
                ret = __clk_notify(core, PRE_RATE_CHANGE, core->rate, new_rate);

        if (ret & NOTIFY_STOP_MASK) {
                pr_debug("%s: clk notifier callback for clock %s aborted with error %d\n",
                                __func__, core->name, ret);
                goto out;
        }

        hlist_for_each_entry(child, &core->children, child_node) {
                ret = __clk_speculate_rates(child, new_rate);
                if (ret & NOTIFY_STOP_MASK)
                        break;
        }

out:
        return ret;
}

static void clk_calc_subtree(struct clk_core *core, unsigned long new_rate,
                             struct clk_core *new_parent, u8 p_index)
{
        struct clk_core *child;

        core->new_rate = new_rate;
        core->new_parent = new_parent;
        core->new_parent_index = p_index;
        /* include clk in new parent's PRE_RATE_CHANGE notifications */
        core->new_child = NULL;
        if (new_parent && new_parent != core->parent)
                new_parent->new_child = core;

        hlist_for_each_entry(child, &core->children, child_node) {
                child->new_rate = clk_recalc(child, new_rate);
                clk_calc_subtree(child, child->new_rate, NULL, 0);
        }
}

/*
 * calculate the new rates returning the topmost clock that has to be
 * changed.
 */
static struct clk_core *clk_calc_new_rates(struct clk_core *core,
                                           unsigned long rate)
{
        struct clk_core *top = core;
        struct clk_core *old_parent, *parent;
        unsigned long best_parent_rate = 0;
        unsigned long new_rate;
        unsigned long min_rate;
        unsigned long max_rate;
        int p_index = 0;
        long ret;

        /* sanity */
        if (IS_ERR_OR_NULL(core))
                return NULL;

        /* save parent rate, if it exists */
        parent = old_parent = core->parent;
        if (parent)
                best_parent_rate = parent->rate;

        clk_core_get_boundaries(core, &min_rate, &max_rate);

        /* find the closest rate and parent clk/rate */
        if (clk_core_can_round(core)) {
                struct clk_rate_request req;

                req.rate = rate;
                req.min_rate = min_rate;
                req.max_rate = max_rate;

                clk_core_init_rate_req(core, &req);

                ret = clk_core_determine_round_nolock(core, &req);
                if (ret < 0)
                        return NULL;

                best_parent_rate = req.best_parent_rate;
                new_rate = req.rate;
                parent = req.best_parent_hw ? req.best_parent_hw->core : NULL;

                if (new_rate < min_rate || new_rate > max_rate)
                        return NULL;
        } else if (!parent || !(core->flags & CLK_SET_RATE_PARENT)) {
                /* pass-through clock without adjustable parent */
                core->new_rate = core->rate;
                return NULL;
        } else {
                /* pass-through clock with adjustable parent */
                top = clk_calc_new_rates(parent, rate);
                new_rate = parent->new_rate;
                goto out;
        }

        /* some clocks must be gated to change parent */
        if (parent != old_parent &&
            (core->flags & CLK_SET_PARENT_GATE) && core->prepare_count) {
                pr_debug("%s: %s not gated but wants to reparent\n",
                         __func__, core->name);
                return NULL;
        }

        /* try finding the new parent index */
        if (parent && core->num_parents > 1) {
                p_index = clk_fetch_parent_index(core, parent);
                if (p_index < 0) {
                        pr_debug("%s: clk %s can not be parent of clk %s\n",
                                 __func__, parent->name, core->name);
                        return NULL;
                }
        }

        if ((core->flags & CLK_SET_RATE_PARENT) && parent &&
            best_parent_rate != parent->rate)
                top = clk_calc_new_rates(parent, best_parent_rate);

out:
        clk_calc_subtree(core, new_rate, parent, p_index);

        return top;
}

/*
 * Notify about rate changes in a subtree. Always walk down the whole tree
 * so that in case of an error we can walk down the whole tree again and
 * abort the change.
 */
static struct clk_core *clk_propagate_rate_change(struct clk_core *core,
                                                  unsigned long event)
{
        struct clk_core *child, *tmp_clk, *fail_clk = NULL;
        int ret = NOTIFY_DONE;

        if (core->rate == core->new_rate)
                return NULL;

        if (core->notifier_count) {
                ret = __clk_notify(core, event, core->rate, core->new_rate);
                if (ret & NOTIFY_STOP_MASK)
                        fail_clk = core;
        }

        hlist_for_each_entry(child, &core->children, child_node) {
                /* Skip children who will be reparented to another clock */
                if (child->new_parent && child->new_parent != core)
                        continue;
                tmp_clk = clk_propagate_rate_change(child, event);
                if (tmp_clk)
                        fail_clk = tmp_clk;
        }

        /* handle the new child who might not be in core->children yet */
        if (core->new_child) {
                tmp_clk = clk_propagate_rate_change(core->new_child, event);
                if (tmp_clk)
                        fail_clk = tmp_clk;
        }

        return fail_clk;
}

/*
 * walk down a subtree and set the new rates notifying the rate
 * change on the way
 */
static void clk_change_rate(struct clk_core *core)
{
        struct clk_core *child;
        struct hlist_node *tmp;
        unsigned long old_rate;
        unsigned long best_parent_rate = 0;
        bool skip_set_rate = false;
        struct clk_core *old_parent;
        struct clk_core *parent = NULL;

        old_rate = core->rate;

        if (core->new_parent) {
                parent = core->new_parent;
                best_parent_rate = core->new_parent->rate;
        } else if (core->parent) {
                parent = core->parent;
                best_parent_rate = core->parent->rate;
        }

        if (clk_pm_runtime_get(core))
                return;

        if (core->flags & CLK_SET_RATE_UNGATE) {
                unsigned long flags;

                clk_core_prepare(core);
                flags = clk_enable_lock();
                clk_core_enable(core);
                clk_enable_unlock(flags);
        }

        if (core->new_parent && core->new_parent != core->parent) {
                old_parent = __clk_set_parent_before(core, core->new_parent);
                trace_clk_set_parent(core, core->new_parent);

                if (core->ops->set_rate_and_parent) {
                        skip_set_rate = true;
                        core->ops->set_rate_and_parent(core->hw, core->new_rate,
                                        best_parent_rate,
                                        core->new_parent_index);
                } else if (core->ops->set_parent) {
                        core->ops->set_parent(core->hw, core->new_parent_index);
                }

                trace_clk_set_parent_complete(core, core->new_parent);
                __clk_set_parent_after(core, core->new_parent, old_parent);
        }

        if (core->flags & CLK_OPS_PARENT_ENABLE)
                clk_core_prepare_enable(parent);

        trace_clk_set_rate(core, core->new_rate);

        if (!skip_set_rate && core->ops->set_rate)
                core->ops->set_rate(core->hw, core->new_rate, best_parent_rate);

        trace_clk_set_rate_complete(core, core->new_rate);

        core->rate = clk_recalc(core, best_parent_rate);

        if (core->flags & CLK_SET_RATE_UNGATE) {
                unsigned long flags;

                flags = clk_enable_lock();
                clk_core_disable(core);
                clk_enable_unlock(flags);
                clk_core_unprepare(core);
        }

        if (core->flags & CLK_OPS_PARENT_ENABLE)
                clk_core_disable_unprepare(parent);

        if (core->notifier_count && old_rate != core->rate)
                __clk_notify(core, POST_RATE_CHANGE, old_rate, core->rate);

        if (core->flags & CLK_RECALC_NEW_RATES)
                (void)clk_calc_new_rates(core, core->new_rate);

        /*
         * Use safe iteration, as change_rate can actually swap parents
         * for certain clock types.
         */
        hlist_for_each_entry_safe(child, tmp, &core->children, child_node) {
                /* Skip children who will be reparented to another clock */
                if (child->new_parent && child->new_parent != core)
                        continue;
                clk_change_rate(child);
        }

        /* handle the new child who might not be in core->children yet */
        if (core->new_child)
                clk_change_rate(core->new_child);

        clk_pm_runtime_put(core);
}

static unsigned long clk_core_req_round_rate_nolock(struct clk_core *core,
                                                     unsigned long req_rate)
{
        int ret, cnt;
        struct clk_rate_request req;

        lockdep_assert_held(&prepare_lock);

        if (!core)
                return 0;

        /* simulate what the rate would be if it could be freely set */
        cnt = clk_core_rate_nuke_protect(core);
        if (cnt < 0)
                return cnt;

        clk_core_get_boundaries(core, &req.min_rate, &req.max_rate);
        req.rate = req_rate;

        ret = clk_core_round_rate_nolock(core, &req);

        /* restore the protection */
        clk_core_rate_restore_protect(core, cnt);

        return ret ? 0 : req.rate;
}

static int clk_core_set_rate_nolock(struct clk_core *core,
                                    unsigned long req_rate)
{
        struct clk_core *top, *fail_clk;
        unsigned long rate;
        int ret = 0;

        if (!core)
                return 0;

        rate = clk_core_req_round_rate_nolock(core, req_rate);

        /* bail early if nothing to do */
        if (rate == clk_core_get_rate_nolock(core))
                return 0;

        /* fail on a direct rate set of a protected provider */
        if (clk_core_rate_is_protected(core))
                return -EBUSY;

        /* calculate new rates and get the topmost changed clock */
        top = clk_calc_new_rates(core, req_rate);
        if (!top)
                return -EINVAL;

        ret = clk_pm_runtime_get(core);
        if (ret)
                return ret;

        /* notify that we are about to change rates */
        fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE);
        if (fail_clk) {
                pr_debug("%s: failed to set %s rate\n", __func__,
                                fail_clk->name);
                clk_propagate_rate_change(top, ABORT_RATE_CHANGE);
                ret = -EBUSY;
                goto err;
        }

        /* change the rates */
        clk_change_rate(top);

        core->req_rate = req_rate;
err:
        clk_pm_runtime_put(core);

        return ret;
}

/**
 * clk_set_rate - specify a new rate for clk
 * @clk: the clk whose rate is being changed
 * @rate: the new rate for clk
 *
 * In the simplest case clk_set_rate will only adjust the rate of clk.
 *
 * Setting the CLK_SET_RATE_PARENT flag allows the rate change operation to
 * propagate up to clk's parent; whether or not this happens depends on the
 * outcome of clk's .round_rate implementation.  If *parent_rate is unchanged
 * after calling .round_rate then upstream parent propagation is ignored.  If
 * *parent_rate comes back with a new rate for clk's parent then we propagate
 * up to clk's parent and set its rate.  Upward propagation will continue
 * until either a clk does not support the CLK_SET_RATE_PARENT flag or
 * .round_rate stops requesting changes to clk's parent_rate.
 *
 * Rate changes are accomplished via tree traversal that also recalculates the
 * rates for the clocks and fires off POST_RATE_CHANGE notifiers.
 *
 * Returns 0 on success, -EERROR otherwise.
 */
int clk_set_rate(struct clk *clk, unsigned long rate)
{
        int ret;

        if (!clk)
                return 0;

        /* prevent racing with updates to the clock topology */
        clk_prepare_lock();

        if (clk->exclusive_count)
                clk_core_rate_unprotect(clk->core);

        ret = clk_core_set_rate_nolock(clk->core, rate);

        if (clk->exclusive_count)
                clk_core_rate_protect(clk->core);

        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_set_rate);

/**
 * clk_set_rate_exclusive - specify a new rate get exclusive control
 * @clk: the clk whose rate is being changed
 * @rate: the new rate for clk
 *
 * This is a combination of clk_set_rate() and clk_rate_exclusive_get()
 * within a critical section
 *
 * This can be used initially to ensure that at least 1 consumer is
 * statisfied when several consumers are competing for exclusivity over the
 * same clock provider.
 *
 * The exclusivity is not applied if setting the rate failed.
 *
 * Calls to clk_rate_exclusive_get() should be balanced with calls to
 * clk_rate_exclusive_put().
 *
 * Returns 0 on success, -EERROR otherwise.
 */
int clk_set_rate_exclusive(struct clk *clk, unsigned long rate)
{
        int ret;

        if (!clk)
                return 0;

        /* prevent racing with updates to the clock topology */
        clk_prepare_lock();

        /*
         * The temporary protection removal is not here, on purpose
         * This function is meant to be used instead of clk_rate_protect,
         * so before the consumer code path protect the clock provider
         */

        ret = clk_core_set_rate_nolock(clk->core, rate);
        if (!ret) {
                clk_core_rate_protect(clk->core);
                clk->exclusive_count++;
        }

        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_set_rate_exclusive);

/**
 * clk_set_rate_range - set a rate range for a clock source
 * @clk: clock source
 * @min: desired minimum clock rate in Hz, inclusive
 * @max: desired maximum clock rate in Hz, inclusive
 *
 * Returns success (0) or negative errno.
 */
int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max)
{
        int ret = 0;
        unsigned long old_min, old_max, rate;

        if (!clk)
                return 0;

        if (min > max) {
                pr_err("%s: clk %s dev %s con %s: invalid range [%lu, %lu]\n",
                       __func__, clk->core->name, clk->dev_id, clk->con_id,
                       min, max);
                return -EINVAL;
        }

        clk_prepare_lock();

        if (clk->exclusive_count)
                clk_core_rate_unprotect(clk->core);

        /* Save the current values in case we need to rollback the change */
        old_min = clk->min_rate;
        old_max = clk->max_rate;
        clk->min_rate = min;
        clk->max_rate = max;

        rate = clk_core_get_rate_nolock(clk->core);
        if (rate < min || rate > max) {
                /*
                 * FIXME:
                 * We are in bit of trouble here, current rate is outside the
                 * the requested range. We are going try to request appropriate
                 * range boundary but there is a catch. It may fail for the
                 * usual reason (clock broken, clock protected, etc) but also
                 * because:
                 * - round_rate() was not favorable and fell on the wrong
                 *   side of the boundary
                 * - the determine_rate() callback does not really check for
                 *   this corner case when determining the rate
                 */

                if (rate < min)
                        rate = min;
                else
                        rate = max;

                ret = clk_core_set_rate_nolock(clk->core, rate);
                if (ret) {
                        /* rollback the changes */
                        clk->min_rate = old_min;
                        clk->max_rate = old_max;
                }
        }

        if (clk->exclusive_count)
                clk_core_rate_protect(clk->core);

        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_set_rate_range);

/**
 * clk_set_min_rate - set a minimum clock rate for a clock source
 * @clk: clock source
 * @rate: desired minimum clock rate in Hz, inclusive
 *
 * Returns success (0) or negative errno.
 */
int clk_set_min_rate(struct clk *clk, unsigned long rate)
{
        if (!clk)
                return 0;

        return clk_set_rate_range(clk, rate, clk->max_rate);
}
EXPORT_SYMBOL_GPL(clk_set_min_rate);

/**
 * clk_set_max_rate - set a maximum clock rate for a clock source
 * @clk: clock source
 * @rate: desired maximum clock rate in Hz, inclusive
 *
 * Returns success (0) or negative errno.
 */
int clk_set_max_rate(struct clk *clk, unsigned long rate)
{
        if (!clk)
                return 0;

        return clk_set_rate_range(clk, clk->min_rate, rate);
}
EXPORT_SYMBOL_GPL(clk_set_max_rate);

/**
 * clk_get_parent - return the parent of a clk
 * @clk: the clk whose parent gets returned
 *
 * Simply returns clk->parent.  Returns NULL if clk is NULL.
 */
struct clk *clk_get_parent(struct clk *clk)
{
        struct clk *parent;

        if (!clk)
                return NULL;

        clk_prepare_lock();
        /* TODO: Create a per-user clk and change callers to call clk_put */
        parent = !clk->core->parent ? NULL : clk->core->parent->hw->clk;
        clk_prepare_unlock();

        return parent;
}
EXPORT_SYMBOL_GPL(clk_get_parent);

static struct clk_core *__clk_init_parent(struct clk_core *core)
{
        u8 index = 0;

        if (core->num_parents > 1 && core->ops->get_parent)
                index = core->ops->get_parent(core->hw);

        return clk_core_get_parent_by_index(core, index);
}

static void clk_core_reparent(struct clk_core *core,
                                  struct clk_core *new_parent)
{
        clk_reparent(core, new_parent);
        __clk_recalc_accuracies(core);
        __clk_recalc_rates(core, POST_RATE_CHANGE);
}

void clk_hw_reparent(struct clk_hw *hw, struct clk_hw *new_parent)
{
        if (!hw)
                return;

        clk_core_reparent(hw->core, !new_parent ? NULL : new_parent->core);
}

/**
 * clk_has_parent - check if a clock is a possible parent for another
 * @clk: clock source
 * @parent: parent clock source
 *
 * This function can be used in drivers that need to check that a clock can be
 * the parent of another without actually changing the parent.
 *
 * Returns true if @parent is a possible parent for @clk, false otherwise.
 */
bool clk_has_parent(struct clk *clk, struct clk *parent)
{
        struct clk_core *core, *parent_core;

        /* NULL clocks should be nops, so return success if either is NULL. */
        if (!clk || !parent)
                return true;

        core = clk->core;
        parent_core = parent->core;

        /* Optimize for the case where the parent is already the parent. */
        if (core->parent == parent_core)
                return true;

        return match_string(core->parent_names, core->num_parents,
                            parent_core->name) >= 0;
}
EXPORT_SYMBOL_GPL(clk_has_parent);

static int clk_core_set_parent_nolock(struct clk_core *core,
                                      struct clk_core *parent)
{
        int ret = 0;
        int p_index = 0;
        unsigned long p_rate = 0;

        lockdep_assert_held(&prepare_lock);

        if (!core)
                return 0;

        if (core->parent == parent)
                return 0;

        /* verify ops for for multi-parent clks */
        if (core->num_parents > 1 && !core->ops->set_parent)
                return -EPERM;

        /* check that we are allowed to re-parent if the clock is in use */
        if ((core->flags & CLK_SET_PARENT_GATE) && core->prepare_count)
                return -EBUSY;

        if (clk_core_rate_is_protected(core))
                return -EBUSY;

        /* try finding the new parent index */
        if (parent) {
                p_index = clk_fetch_parent_index(core, parent);
                if (p_index < 0) {
                        pr_debug("%s: clk %s can not be parent of clk %s\n",
                                        __func__, parent->name, core->name);
                        return p_index;
                }
                p_rate = parent->rate;
        }

        ret = clk_pm_runtime_get(core);
        if (ret)
                return ret;

        /* propagate PRE_RATE_CHANGE notifications */
        ret = __clk_speculate_rates(core, p_rate);

        /* abort if a driver objects */
        if (ret & NOTIFY_STOP_MASK)
                goto runtime_put;

        /* do the re-parent */
        ret = __clk_set_parent(core, parent, p_index);

        /* propagate rate an accuracy recalculation accordingly */
        if (ret) {
                __clk_recalc_rates(core, ABORT_RATE_CHANGE);
        } else {
                __clk_recalc_rates(core, POST_RATE_CHANGE);
                __clk_recalc_accuracies(core);
        }

runtime_put:
        clk_pm_runtime_put(core);

        return ret;
}

/**
 * clk_set_parent - switch the parent of a mux clk
 * @clk: the mux clk whose input we are switching
 * @parent: the new input to clk
 *
 * Re-parent clk to use parent as its new input source.  If clk is in
 * prepared state, the clk will get enabled for the duration of this call. If
 * that's not acceptable for a specific clk (Eg: the consumer can't handle
 * that, the reparenting is glitchy in hardware, etc), use the
 * CLK_SET_PARENT_GATE flag to allow reparenting only when clk is unprepared.
 *
 * After successfully changing clk's parent clk_set_parent will update the
 * clk topology, sysfs topology and propagate rate recalculation via
 * __clk_recalc_rates.
 *
 * Returns 0 on success, -EERROR otherwise.
 */
int clk_set_parent(struct clk *clk, struct clk *parent)
{
        int ret;

        if (!clk)
                return 0;

        clk_prepare_lock();

        if (clk->exclusive_count)
                clk_core_rate_unprotect(clk->core);

        ret = clk_core_set_parent_nolock(clk->core,
                                         parent ? parent->core : NULL);

        if (clk->exclusive_count)
                clk_core_rate_protect(clk->core);

        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_set_parent);

static int clk_core_set_phase_nolock(struct clk_core *core, int degrees)
{
        int ret = -EINVAL;

        lockdep_assert_held(&prepare_lock);

        if (!core)
                return 0;

        if (clk_core_rate_is_protected(core))
                return -EBUSY;

        trace_clk_set_phase(core, degrees);

        if (core->ops->set_phase) {
                ret = core->ops->set_phase(core->hw, degrees);
                if (!ret)
                        core->phase = degrees;
        }

        trace_clk_set_phase_complete(core, degrees);

        return ret;
}

/**
 * clk_set_phase - adjust the phase shift of a clock signal
 * @clk: clock signal source
 * @degrees: number of degrees the signal is shifted
 *
 * Shifts the phase of a clock signal by the specified
 * degrees. Returns 0 on success, -EERROR otherwise.
 *
 * This function makes no distinction about the input or reference
 * signal that we adjust the clock signal phase against. For example
 * phase locked-loop clock signal generators we may shift phase with
 * respect to feedback clock signal input, but for other cases the
 * clock phase may be shifted with respect to some other, unspecified
 * signal.
 *
 * Additionally the concept of phase shift does not propagate through
 * the clock tree hierarchy, which sets it apart from clock rates and
 * clock accuracy. A parent clock phase attribute does not have an
 * impact on the phase attribute of a child clock.
 */
int clk_set_phase(struct clk *clk, int degrees)
{
        int ret;

        if (!clk)
                return 0;

        /* sanity check degrees */
        degrees %= 360;
        if (degrees < 0)
                degrees += 360;

        clk_prepare_lock();

        if (clk->exclusive_count)
                clk_core_rate_unprotect(clk->core);

        ret = clk_core_set_phase_nolock(clk->core, degrees);

        if (clk->exclusive_count)
                clk_core_rate_protect(clk->core);

        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_set_phase);

static int clk_core_get_phase(struct clk_core *core)
{
        int ret;

        clk_prepare_lock();
        /* Always try to update cached phase if possible */
        if (core->ops->get_phase)
                core->phase = core->ops->get_phase(core->hw);
        ret = core->phase;
        clk_prepare_unlock();

        return ret;
}

/**
 * clk_get_phase - return the phase shift of a clock signal
 * @clk: clock signal source
 *
 * Returns the phase shift of a clock node in degrees, otherwise returns
 * -EERROR.
 */
int clk_get_phase(struct clk *clk)
{
        if (!clk)
                return 0;

        return clk_core_get_phase(clk->core);
}
EXPORT_SYMBOL_GPL(clk_get_phase);

static void clk_core_reset_duty_cycle_nolock(struct clk_core *core)
{
        /* Assume a default value of 50% */
        core->duty.num = 1;
        core->duty.den = 2;
}

static int clk_core_update_duty_cycle_parent_nolock(struct clk_core *core);

static int clk_core_update_duty_cycle_nolock(struct clk_core *core)
{
        struct clk_duty *duty = &core->duty;
        int ret = 0;

        if (!core->ops->get_duty_cycle)
                return clk_core_update_duty_cycle_parent_nolock(core);

        ret = core->ops->get_duty_cycle(core->hw, duty);
        if (ret)
                goto reset;

        /* Don't trust the clock provider too much */
        if (duty->den == 0 || duty->num > duty->den) {
                ret = -EINVAL;
                goto reset;
        }

        return 0;

reset:
        clk_core_reset_duty_cycle_nolock(core);
        return ret;
}

static int clk_core_update_duty_cycle_parent_nolock(struct clk_core *core)
{
        int ret = 0;

        if (core->parent &&
            core->flags & CLK_DUTY_CYCLE_PARENT) {
                ret = clk_core_update_duty_cycle_nolock(core->parent);
                memcpy(&core->duty, &core->parent->duty, sizeof(core->duty));
        } else {
                clk_core_reset_duty_cycle_nolock(core);
        }

        return ret;
}

static int clk_core_set_duty_cycle_parent_nolock(struct clk_core *core,
                                                 struct clk_duty *duty);

static int clk_core_set_duty_cycle_nolock(struct clk_core *core,
                                          struct clk_duty *duty)
{
        int ret;

        lockdep_assert_held(&prepare_lock);

        if (clk_core_rate_is_protected(core))
                return -EBUSY;

        trace_clk_set_duty_cycle(core, duty);

        if (!core->ops->set_duty_cycle)
                return clk_core_set_duty_cycle_parent_nolock(core, duty);

        ret = core->ops->set_duty_cycle(core->hw, duty);
        if (!ret)
                memcpy(&core->duty, duty, sizeof(*duty));

        trace_clk_set_duty_cycle_complete(core, duty);

        return ret;
}

static int clk_core_set_duty_cycle_parent_nolock(struct clk_core *core,
                                                 struct clk_duty *duty)
{
        int ret = 0;

        if (core->parent &&
            core->flags & (CLK_DUTY_CYCLE_PARENT | CLK_SET_RATE_PARENT)) {
                ret = clk_core_set_duty_cycle_nolock(core->parent, duty);
                memcpy(&core->duty, &core->parent->duty, sizeof(core->duty));
        }

        return ret;
}

/**
 * clk_set_duty_cycle - adjust the duty cycle ratio of a clock signal
 * @clk: clock signal source
 * @num: numerator of the duty cycle ratio to be applied
 * @den: denominator of the duty cycle ratio to be applied
 *
 * Apply the duty cycle ratio if the ratio is valid and the clock can
 * perform this operation
 *
 * Returns (0) on success, a negative errno otherwise.
 */
int clk_set_duty_cycle(struct clk *clk, unsigned int num, unsigned int den)
{
        int ret;
        struct clk_duty duty;

        if (!clk)
                return 0;

        /* sanity check the ratio */
        if (den == 0 || num > den)
                return -EINVAL;

        duty.num = num;
        duty.den = den;

        clk_prepare_lock();

        if (clk->exclusive_count)
                clk_core_rate_unprotect(clk->core);

        ret = clk_core_set_duty_cycle_nolock(clk->core, &duty);

        if (clk->exclusive_count)
                clk_core_rate_protect(clk->core);

        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_set_duty_cycle);

static int clk_core_get_scaled_duty_cycle(struct clk_core *core,
                                          unsigned int scale)
{
        struct clk_duty *duty = &core->duty;
        int ret;

        clk_prepare_lock();

        ret = clk_core_update_duty_cycle_nolock(core);
        if (!ret)
                ret = mult_frac(scale, duty->num, duty->den);

        clk_prepare_unlock();

        return ret;
}

/**
 * clk_get_scaled_duty_cycle - return the duty cycle ratio of a clock signal
 * @clk: clock signal source
 * @scale: scaling factor to be applied to represent the ratio as an integer
 *
 * Returns the duty cycle ratio of a clock node multiplied by the provided
 * scaling factor, or negative errno on error.
 */
int clk_get_scaled_duty_cycle(struct clk *clk, unsigned int scale)
{
        if (!clk)
                return 0;

        return clk_core_get_scaled_duty_cycle(clk->core, scale);
}
EXPORT_SYMBOL_GPL(clk_get_scaled_duty_cycle);

/**
 * clk_is_match - check if two clk's point to the same hardware clock
 * @p: clk compared against q
 * @q: clk compared against p
 *
 * Returns true if the two struct clk pointers both point to the same hardware
 * clock node. Put differently, returns true if struct clk *p and struct clk *q
 * share the same struct clk_core object.
 *
 * Returns false otherwise. Note that two NULL clks are treated as matching.
 */
bool clk_is_match(const struct clk *p, const struct clk *q)
{
        /* trivial case: identical struct clk's or both NULL */
        if (p == q)
                return true;

        /* true if clk->core pointers match. Avoid dereferencing garbage */
        if (!IS_ERR_OR_NULL(p) && !IS_ERR_OR_NULL(q))
                if (p->core == q->core)
                        return true;

        return false;
}
EXPORT_SYMBOL_GPL(clk_is_match);

/***        debugfs support        ***/

#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>

static struct dentry *rootdir;
static int inited = 0;
static DEFINE_MUTEX(clk_debug_lock);
static HLIST_HEAD(clk_debug_list);

static struct hlist_head *all_lists[] = {
        &clk_root_list,
        &clk_orphan_list,
        NULL,
};

static struct hlist_head *orphan_list[] = {
        &clk_orphan_list,
        NULL,
};

static void clk_summary_show_one(struct seq_file *s, struct clk_core *c,
                                 int level)
{
        if (!c)
                return;

        seq_printf(s, "%*s%-*s %7d %8d %8d %11lu %10lu %5d %6d\n",
                   level * 3 + 1, "",
                   30 - level * 3, c->name,
                   c->enable_count, c->prepare_count, c->protect_count,
                   clk_core_get_rate(c), clk_core_get_accuracy(c),
                   clk_core_get_phase(c),
                   clk_core_get_scaled_duty_cycle(c, 100000));
}

static void clk_summary_show_subtree(struct seq_file *s, struct clk_core *c,
                                     int level)
{
        struct clk_core *child;

        if (!c)
                return;

        clk_summary_show_one(s, c, level);

        hlist_for_each_entry(child, &c->children, child_node)
                clk_summary_show_subtree(s, child, level + 1);
}

static int clk_summary_show(struct seq_file *s, void *data)
{
        struct clk_core *c;
        struct hlist_head **lists = (struct hlist_head **)s->private;

        seq_puts(s, "                                 enable  prepare  protect                                duty\n");
        seq_puts(s, "   clock                          count    count    count        rate   accuracy phase  cycle\n");
        seq_puts(s, "---------------------------------------------------------------------------------------------\n");

        clk_prepare_lock();

        for (; *lists; lists++)
                hlist_for_each_entry(c, *lists, child_node)
                        clk_summary_show_subtree(s, c, 0);

        clk_prepare_unlock();

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(clk_summary);

static void clk_dump_one(struct seq_file *s, struct clk_core *c, int level)
{
        if (!c)
                return;

        /* This should be JSON format, i.e. elements separated with a comma */
        seq_printf(s, "\"%s\": { ", c->name);
        seq_printf(s, "\"enable_count\": %d,", c->enable_count);
        seq_printf(s, "\"prepare_count\": %d,", c->prepare_count);
        seq_printf(s, "\"protect_count\": %d,", c->protect_count);
        seq_printf(s, "\"rate\": %lu,", clk_core_get_rate(c));
        seq_printf(s, "\"accuracy\": %lu,", clk_core_get_accuracy(c));
        seq_printf(s, "\"phase\": %d,", clk_core_get_phase(c));
        seq_printf(s, "\"duty_cycle\": %u",
                   clk_core_get_scaled_duty_cycle(c, 100000));
}

static void clk_dump_subtree(struct seq_file *s, struct clk_core *c, int level)
{
        struct clk_core *child;

        if (!c)
                return;

        clk_dump_one(s, c, level);

        hlist_for_each_entry(child, &c->children, child_node) {
                seq_putc(s, ',');
                clk_dump_subtree(s, child, level + 1);
        }

        seq_putc(s, '}');
}

static int clk_dump_show(struct seq_file *s, void *data)
{
        struct clk_core *c;
        bool first_node = true;
        struct hlist_head **lists = (struct hlist_head **)s->private;

        seq_putc(s, '{');
        clk_prepare_lock();

        for (; *lists; lists++) {
                hlist_for_each_entry(c, *lists, child_node) {
                        if (!first_node)
                                seq_putc(s, ',');
                        first_node = false;
                        clk_dump_subtree(s, c, 0);
                }
        }

        clk_prepare_unlock();

        seq_puts(s, "}\n");
        return 0;
}
DEFINE_SHOW_ATTRIBUTE(clk_dump);

static const struct {
        unsigned long flag;
        const char *name;
} clk_flags[] = {
#define ENTRY(f) { f, #f }
        ENTRY(CLK_SET_RATE_GATE),
        ENTRY(CLK_SET_PARENT_GATE),
        ENTRY(CLK_SET_RATE_PARENT),
        ENTRY(CLK_IGNORE_UNUSED),
        ENTRY(CLK_IS_BASIC),
        ENTRY(CLK_GET_RATE_NOCACHE),
        ENTRY(CLK_SET_RATE_NO_REPARENT),
        ENTRY(CLK_GET_ACCURACY_NOCACHE),
        ENTRY(CLK_RECALC_NEW_RATES),
        ENTRY(CLK_SET_RATE_UNGATE),
        ENTRY(CLK_IS_CRITICAL),
        ENTRY(CLK_OPS_PARENT_ENABLE),
        ENTRY(CLK_DUTY_CYCLE_PARENT),
#undef ENTRY
};

static int clk_flags_show(struct seq_file *s, void *data)
{
        struct clk_core *core = s->private;
        unsigned long flags = core->flags;
        unsigned int i;

        for (i = 0; flags && i < ARRAY_SIZE(clk_flags); i++) {
                if (flags & clk_flags[i].flag) {
                        seq_printf(s, "%s\n", clk_flags[i].name);
                        flags &= ~clk_flags[i].flag;
                }
        }
        if (flags) {
                /* Unknown flags */
                seq_printf(s, "0x%lx\n", flags);
        }

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(clk_flags);

static int possible_parents_show(struct seq_file *s, void *data)
{
        struct clk_core *core = s->private;
        int i;

        for (i = 0; i < core->num_parents - 1; i++)
                seq_printf(s, "%s ", core->parent_names[i]);

        seq_printf(s, "%s\n", core->parent_names[i]);

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(possible_parents);

static int clk_duty_cycle_show(struct seq_file *s, void *data)
{
        struct clk_core *core = s->private;
        struct clk_duty *duty = &core->duty;

        seq_printf(s, "%u/%u\n", duty->num, duty->den);

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(clk_duty_cycle);

static void clk_debug_create_one(struct clk_core *core, struct dentry *pdentry)
{
        struct dentry *root;

        if (!core || !pdentry)
                return;

        root = debugfs_create_dir(core->name, pdentry);
        core->dentry = root;

        debugfs_create_ulong("clk_rate", 0444, root, &core->rate);
        debugfs_create_ulong("clk_accuracy", 0444, root, &core->accuracy);
        debugfs_create_u32("clk_phase", 0444, root, &core->phase);
        debugfs_create_file("clk_flags", 0444, root, core, &clk_flags_fops);
        debugfs_create_u32("clk_prepare_count", 0444, root, &core->prepare_count);
        debugfs_create_u32("clk_enable_count", 0444, root, &core->enable_count);
        debugfs_create_u32("clk_protect_count", 0444, root, &core->protect_count);
        debugfs_create_u32("clk_notifier_count", 0444, root, &core->notifier_count);
        debugfs_create_file("clk_duty_cycle", 0444, root, core,
                            &clk_duty_cycle_fops);

        if (core->num_parents > 1)
                debugfs_create_file("clk_possible_parents", 0444, root, core,
                                    &possible_parents_fops);

        if (core->ops->debug_init)
                core->ops->debug_init(core->hw, core->dentry);
}

/**
 * clk_debug_register - add a clk node to the debugfs clk directory
 * @core: the clk being added to the debugfs clk directory
 *
 * Dynamically adds a clk to the debugfs clk directory if debugfs has been
 * initialized.  Otherwise it bails out early since the debugfs clk directory
 * will be created lazily by clk_debug_init as part of a late_initcall.
 */
static void clk_debug_register(struct clk_core *core)
{
        mutex_lock(&clk_debug_lock);
        hlist_add_head(&core->debug_node, &clk_debug_list);
        if (inited)
                clk_debug_create_one(core, rootdir);
        mutex_unlock(&clk_debug_lock);
}

 /**
 * clk_debug_unregister - remove a clk node from the debugfs clk directory
 * @core: the clk being removed from the debugfs clk directory
 *
 * Dynamically removes a clk and all its child nodes from the
 * debugfs clk directory if clk->dentry points to debugfs created by
 * clk_debug_register in __clk_core_init.
 */
static void clk_debug_unregister(struct clk_core *core)
{
        mutex_lock(&clk_debug_lock);
        hlist_del_init(&core->debug_node);
        debugfs_remove_recursive(core->dentry);
        core->dentry = NULL;
        mutex_unlock(&clk_debug_lock);
}

/**
 * clk_debug_init - lazily populate the debugfs clk directory
 *
 * clks are often initialized very early during boot before memory can be
 * dynamically allocated and well before debugfs is setup. This function
 * populates the debugfs clk directory once at boot-time when we know that
 * debugfs is setup. It should only be called once at boot-time, all other clks
 * added dynamically will be done so with clk_debug_register.
 */
static int __init clk_debug_init(void)
{
        struct clk_core *core;

        rootdir = debugfs_create_dir("clk", NULL);

        debugfs_create_file("clk_summary", 0444, rootdir, &all_lists,
                            &clk_summary_fops);
        debugfs_create_file("clk_dump", 0444, rootdir, &all_lists,
                            &clk_dump_fops);
        debugfs_create_file("clk_orphan_summary", 0444, rootdir, &orphan_list,
                            &clk_summary_fops);
        debugfs_create_file("clk_orphan_dump", 0444, rootdir, &orphan_list,
                            &clk_dump_fops);

        mutex_lock(&clk_debug_lock);
        hlist_for_each_entry(core, &clk_debug_list, debug_node)
                clk_debug_create_one(core, rootdir);

        inited = 1;
        mutex_unlock(&clk_debug_lock);

        return 0;
}
late_initcall(clk_debug_init);
#else
static inline void clk_debug_register(struct clk_core *core) { }
static inline void clk_debug_reparent(struct clk_core *core,
                                      struct clk_core *new_parent)
{
}
static inline void clk_debug_unregister(struct clk_core *core)
{
}
#endif

/**
 * __clk_core_init - initialize the data structures in a struct clk_core
 * @core:       clk_core being initialized
 *
 * Initializes the lists in struct clk_core, queries the hardware for the
 * parent and rate and sets them both.
 */
static int __clk_core_init(struct clk_core *core)
{
        int i, ret;
        struct clk_core *orphan;
        struct hlist_node *tmp2;
        unsigned long rate;

        if (!core)
                return -EINVAL;

        clk_prepare_lock();

        ret = clk_pm_runtime_get(core);
        if (ret)
                goto unlock;

        /* check to see if a clock with this name is already registered */
        if (clk_core_lookup(core->name)) {
                pr_debug("%s: clk %s already initialized\n",
                                __func__, core->name);
                ret = -EEXIST;
                goto out;
        }

        /* check that clk_ops are sane.  See Documentation/driver-api/clk.rst */
        if (core->ops->set_rate &&
            !((core->ops->round_rate || core->ops->determine_rate) &&
              core->ops->recalc_rate)) {
                pr_err("%s: %s must implement .round_rate or .determine_rate in addition to .recalc_rate\n",
                       __func__, core->name);
                ret = -EINVAL;
                goto out;
        }

        if (core->ops->set_parent && !core->ops->get_parent) {
                pr_err("%s: %s must implement .get_parent & .set_parent\n",
                       __func__, core->name);
                ret = -EINVAL;
                goto out;
        }

        if (core->num_parents > 1 && !core->ops->get_parent) {
                pr_err("%s: %s must implement .get_parent as it has multi parents\n",
                       __func__, core->name);
                ret = -EINVAL;
                goto out;
        }

        if (core->ops->set_rate_and_parent &&
                        !(core->ops->set_parent && core->ops->set_rate)) {
                pr_err("%s: %s must implement .set_parent & .set_rate\n",
                                __func__, core->name);
                ret = -EINVAL;
                goto out;
        }

        /* throw a WARN if any entries in parent_names are NULL */
        for (i = 0; i < core->num_parents; i++)
                WARN(!core->parent_names[i],
                                "%s: invalid NULL in %s's .parent_names\n",
                                __func__, core->name);

        core->parent = __clk_init_parent(core);

        /*
         * Populate core->parent if parent has already been clk_core_init'd. If
         * parent has not yet been clk_core_init'd then place clk in the orphan
         * list.  If clk doesn't have any parents then place it in the root
         * clk list.
         *
         * Every time a new clk is clk_init'd then we walk the list of orphan
         * clocks and re-parent any that are children of the clock currently
         * being clk_init'd.
         */
        if (core->parent) {
                hlist_add_head(&core->child_node,
                                &core->parent->children);
                core->orphan = core->parent->orphan;
        } else if (!core->num_parents) {
                hlist_add_head(&core->child_node, &clk_root_list);
                core->orphan = false;
        } else {
                hlist_add_head(&core->child_node, &clk_orphan_list);
                core->orphan = true;
        }

        /*
         * optional platform-specific magic
         *
         * The .init callback is not used by any of the basic clock types, but
         * exists for weird hardware that must perform initialization magic.
         * Please consider other ways of solving initialization problems before
         * using this callback, as its use is discouraged.
         */
        if (core->ops->init)
                core->ops->init(core->hw);

        /*
         * Set clk's accuracy.  The preferred method is to use
         * .recalc_accuracy. For simple clocks and lazy developers the default
         * fallback is to use the parent's accuracy.  If a clock doesn't have a
         * parent (or is orphaned) then accuracy is set to zero (perfect
         * clock).
         */
        if (core->ops->recalc_accuracy)
                core->accuracy = core->ops->recalc_accuracy(core->hw,
                                        __clk_get_accuracy(core->parent));
        else if (core->parent)
                core->accuracy = core->parent->accuracy;
        else
                core->accuracy = 0;

        /*
         * Set clk's phase.
         * Since a phase is by definition relative to its parent, just
         * query the current clock phase, or just assume it's in phase.
         */
        if (core->ops->get_phase)
                core->phase = core->ops->get_phase(core->hw);
        else
                core->phase = 0;

        /*
         * Set clk's duty cycle.
         */
        clk_core_update_duty_cycle_nolock(core);

        /*
         * Set clk's rate.  The preferred method is to use .recalc_rate.  For
         * simple clocks and lazy developers the default fallback is to use the
         * parent's rate.  If a clock doesn't have a parent (or is orphaned)
         * then rate is set to zero.
         */
        if (core->ops->recalc_rate)
                rate = core->ops->recalc_rate(core->hw,
                                clk_core_get_rate_nolock(core->parent));
        else if (core->parent)
                rate = core->parent->rate;
        else
                rate = 0;
        core->rate = core->req_rate = rate;

        /*
         * Enable CLK_IS_CRITICAL clocks so newly added critical clocks
         * don't get accidentally disabled when walking the orphan tree and
         * reparenting clocks
         */
        if (core->flags & CLK_IS_CRITICAL) {
                unsigned long flags;

                clk_core_prepare(core);

                flags = clk_enable_lock();
                clk_core_enable(core);
                clk_enable_unlock(flags);
        }

        /*
         * walk the list of orphan clocks and reparent any that newly finds a
         * parent.
         */
        hlist_for_each_entry_safe(orphan, tmp2, &clk_orphan_list, child_node) {
                struct clk_core *parent = __clk_init_parent(orphan);

                /*
                 * We need to use __clk_set_parent_before() and _after() to
                 * to properly migrate any prepare/enable count of the orphan
                 * clock. This is important for CLK_IS_CRITICAL clocks, which
                 * are enabled during init but might not have a parent yet.
                 */
                if (parent) {
                        /* update the clk tree topology */
                        __clk_set_parent_before(orphan, parent);
                        __clk_set_parent_after(orphan, parent, NULL);
                        __clk_recalc_accuracies(orphan);
                        __clk_recalc_rates(orphan, 0);
                }
        }

        kref_init(&core->ref);
out:
        clk_pm_runtime_put(core);
unlock:
        clk_prepare_unlock();

        if (!ret)
                clk_debug_register(core);

        return ret;
}

/**
 * clk_core_link_consumer - Add a clk consumer to the list of consumers in a clk_core
 * @core: clk to add consumer to
 * @clk: consumer to link to a clk
 */
static void clk_core_link_consumer(struct clk_core *core, struct clk *clk)
{
        clk_prepare_lock();
        hlist_add_head(&clk->clks_node, &core->clks);
        clk_prepare_unlock();
}

/**
 * clk_core_unlink_consumer - Remove a clk consumer from the list of consumers in a clk_core
 * @clk: consumer to unlink
 */
static void clk_core_unlink_consumer(struct clk *clk)
{
        lockdep_assert_held(&prepare_lock);
        hlist_del(&clk->clks_node);
}

/**
 * alloc_clk - Allocate a clk consumer, but leave it unlinked to the clk_core
 * @core: clk to allocate a consumer for
 * @dev_id: string describing device name
 * @con_id: connection ID string on device
 *
 * Returns: clk consumer left unlinked from the consumer list
 */
static struct clk *alloc_clk(struct clk_core *core, const char *dev_id,
                             const char *con_id)
{
        struct clk *clk;

        clk = kzalloc(sizeof(*clk), GFP_KERNEL);
        if (!clk)
                return ERR_PTR(-ENOMEM);

        clk->core = core;
        clk->dev_id = dev_id;
        clk->con_id = kstrdup_const(con_id, GFP_KERNEL);
        clk->max_rate = ULONG_MAX;

        return clk;
}

/**
 * free_clk - Free a clk consumer
 * @clk: clk consumer to free
 *
 * Note, this assumes the clk has been unlinked from the clk_core consumer
 * list.
 */
static void free_clk(struct clk *clk)
{
        kfree_const(clk->con_id);
        kfree(clk);
}

/**
 * clk_hw_create_clk: Allocate and link a clk consumer to a clk_core given
 * a clk_hw
 * @dev: clk consumer device
 * @hw: clk_hw associated with the clk being consumed
 * @dev_id: string describing device name
 * @con_id: connection ID string on device
 *
 * This is the main function used to create a clk pointer for use by clk
 * consumers. It connects a consumer to the clk_core and clk_hw structures
 * used by the framework and clk provider respectively.
 */
struct clk *clk_hw_create_clk(struct device *dev, struct clk_hw *hw,
                              const char *dev_id, const char *con_id)
{
        struct clk *clk;
        struct clk_core *core;

        /* This is to allow this function to be chained to others */
        if (IS_ERR_OR_NULL(hw))
                return ERR_CAST(hw);

        core = hw->core;
        clk = alloc_clk(core, dev_id, con_id);
        if (IS_ERR(clk))
                return clk;
        clk->dev = dev;

        if (!try_module_get(core->owner)) {
                free_clk(clk);
                return ERR_PTR(-ENOENT);
        }

        kref_get(&core->ref);
        clk_core_link_consumer(core, clk);

        return clk;
}

/**
 * clk_register - allocate a new clock, register it and return an opaque cookie
 * @dev: device that is registering this clock
 * @hw: link to hardware-specific clock data
 *
 * clk_register is the *deprecated* interface for populating the clock tree with
 * new clock nodes. Use clk_hw_register() instead.
 *
 * Returns: a pointer to the newly allocated struct clk which
 * cannot be dereferenced by driver code but may be used in conjunction with the
 * rest of the clock API.  In the event of an error clk_register will return an
 * error code; drivers must test for an error code after calling clk_register.
 */
struct clk *clk_register(struct device *dev, struct clk_hw *hw)
{
        int i, ret;
        struct clk_core *core;

        core = kzalloc(sizeof(*core), GFP_KERNEL);
        if (!core) {
                ret = -ENOMEM;
                goto fail_out;
        }

        core->name = kstrdup_const(hw->init->name, GFP_KERNEL);
        if (!core->name) {
                ret = -ENOMEM;
                goto fail_name;
        }

        if (WARN_ON(!hw->init->ops)) {
                ret = -EINVAL;
                goto fail_ops;
        }
        core->ops = hw->init->ops;

        if (dev && pm_runtime_enabled(dev))
                core->rpm_enabled = true;
        core->dev = dev;
        if (dev && dev->driver)
                core->owner = dev->driver->owner;
        core->hw = hw;
        core->flags = hw->init->flags;
        core->num_parents = hw->init->num_parents;
        core->min_rate = 0;
        core->max_rate = ULONG_MAX;
        hw->core = core;

        /* allocate local copy in case parent_names is __initdata */
        core->parent_names = kcalloc(core->num_parents, sizeof(char *),
                                        GFP_KERNEL);

        if (!core->parent_names) {
                ret = -ENOMEM;
                goto fail_parent_names;
        }


        /* copy each string name in case parent_names is __initdata */
        for (i = 0; i < core->num_parents; i++) {
                core->parent_names[i] = kstrdup_const(hw->init->parent_names[i],
                                                GFP_KERNEL);
                if (!core->parent_names[i]) {
                        ret = -ENOMEM;
                        goto fail_parent_names_copy;
                }
        }

        /* avoid unnecessary string look-ups of clk_core's possible parents. */
        core->parents = kcalloc(core->num_parents, sizeof(*core->parents),
                                GFP_KERNEL);
        if (!core->parents) {
                ret = -ENOMEM;
                goto fail_parents;
        };

        INIT_HLIST_HEAD(&core->clks);

        /*
         * Don't call clk_hw_create_clk() here because that would pin the
         * provider module to itself and prevent it from ever being removed.
         */
        hw->clk = alloc_clk(core, NULL, NULL);
        if (IS_ERR(hw->clk)) {
                ret = PTR_ERR(hw->clk);
                goto fail_parents;
        }

        clk_core_link_consumer(hw->core, hw->clk);

        ret = __clk_core_init(core);
        if (!ret)
                return hw->clk;

        clk_prepare_lock();
        clk_core_unlink_consumer(hw->clk);
        clk_prepare_unlock();

        free_clk(hw->clk);
        hw->clk = NULL;

fail_parents:
        kfree(core->parents);
fail_parent_names_copy:
        while (--i >= 0)
                kfree_const(core->parent_names[i]);
        kfree(core->parent_names);
fail_parent_names:
fail_ops:
        kfree_const(core->name);
fail_name:
        kfree(core);
fail_out:
        return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(clk_register);

/**
 * clk_hw_register - register a clk_hw and return an error code
 * @dev: device that is registering this clock
 * @hw: link to hardware-specific clock data
 *
 * clk_hw_register is the primary interface for populating the clock tree with
 * new clock nodes. It returns an integer equal to zero indicating success or
 * less than zero indicating failure. Drivers must test for an error code after
 * calling clk_hw_register().
 */
int clk_hw_register(struct device *dev, struct clk_hw *hw)
{
        return PTR_ERR_OR_ZERO(clk_register(dev, hw));
}
EXPORT_SYMBOL_GPL(clk_hw_register);

/* Free memory allocated for a clock. */
static void __clk_release(struct kref *ref)
{
        struct clk_core *core = container_of(ref, struct clk_core, ref);
        int i = core->num_parents;

        lockdep_assert_held(&prepare_lock);

        kfree(core->parents);
        while (--i >= 0)
                kfree_const(core->parent_names[i]);

        kfree(core->parent_names);
        kfree_const(core->name);
        kfree(core);
}

/*
 * Empty clk_ops for unregistered clocks. These are used temporarily
 * after clk_unregister() was called on a clock and until last clock
 * consumer calls clk_put() and the struct clk object is freed.
 */
static int clk_nodrv_prepare_enable(struct clk_hw *hw)
{
        return -ENXIO;
}

static void clk_nodrv_disable_unprepare(struct clk_hw *hw)
{
        WARN_ON_ONCE(1);
}

static int clk_nodrv_set_rate(struct clk_hw *hw, unsigned long rate,
                                        unsigned long parent_rate)
{
        return -ENXIO;
}

static int clk_nodrv_set_parent(struct clk_hw *hw, u8 index)
{
        return -ENXIO;
}

static const struct clk_ops clk_nodrv_ops = {
        .enable         = clk_nodrv_prepare_enable,
        .disable        = clk_nodrv_disable_unprepare,
        .prepare        = clk_nodrv_prepare_enable,
        .unprepare      = clk_nodrv_disable_unprepare,
        .set_rate       = clk_nodrv_set_rate,
        .set_parent     = clk_nodrv_set_parent,
};

/**
 * clk_unregister - unregister a currently registered clock
 * @clk: clock to unregister
 */
void clk_unregister(struct clk *clk)
{
        unsigned long flags;

        if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
                return;

        clk_debug_unregister(clk->core);

        clk_prepare_lock();

        if (clk->core->ops == &clk_nodrv_ops) {
                pr_err("%s: unregistered clock: %s\n", __func__,
                       clk->core->name);
                goto unlock;
        }
        /*
         * Assign empty clock ops for consumers that might still hold
         * a reference to this clock.
         */
        flags = clk_enable_lock();
        clk->core->ops = &clk_nodrv_ops;
        clk_enable_unlock(flags);

        if (!hlist_empty(&clk->core->children)) {
                struct clk_core *child;
                struct hlist_node *t;

                /* Reparent all children to the orphan list. */
                hlist_for_each_entry_safe(child, t, &clk->core->children,
                                          child_node)
                        clk_core_set_parent_nolock(child, NULL);
        }

        hlist_del_init(&clk->core->child_node);

        if (clk->core->prepare_count)
                pr_warn("%s: unregistering prepared clock: %s\n",
                                        __func__, clk->core->name);

        if (clk->core->protect_count)
                pr_warn("%s: unregistering protected clock: %s\n",
                                        __func__, clk->core->name);

        kref_put(&clk->core->ref, __clk_release);
unlock:
        clk_prepare_unlock();
}
EXPORT_SYMBOL_GPL(clk_unregister);

/**
 * clk_hw_unregister - unregister a currently registered clk_hw
 * @hw: hardware-specific clock data to unregister
 */
void clk_hw_unregister(struct clk_hw *hw)
{
        clk_unregister(hw->clk);
}
EXPORT_SYMBOL_GPL(clk_hw_unregister);

static void devm_clk_release(struct device *dev, void *res)
{
        clk_unregister(*(struct clk **)res);
}

static void devm_clk_hw_release(struct device *dev, void *res)
{
        clk_hw_unregister(*(struct clk_hw **)res);
}

/**
 * devm_clk_register - resource managed clk_register()
 * @dev: device that is registering this clock
 * @hw: link to hardware-specific clock data
 *
 * Managed clk_register(). This function is *deprecated*, use devm_clk_hw_register() instead.
 *
 * Clocks returned from this function are automatically clk_unregister()ed on
 * driver detach. See clk_register() for more information.
 */
struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw)
{
        struct clk *clk;
        struct clk **clkp;

        clkp = devres_alloc(devm_clk_release, sizeof(*clkp), GFP_KERNEL);
        if (!clkp)
                return ERR_PTR(-ENOMEM);

        clk = clk_register(dev, hw);
        if (!IS_ERR(clk)) {
                *clkp = clk;
                devres_add(dev, clkp);
        } else {
                devres_free(clkp);
        }

        return clk;
}
EXPORT_SYMBOL_GPL(devm_clk_register);

/**
 * devm_clk_hw_register - resource managed clk_hw_register()
 * @dev: device that is registering this clock
 * @hw: link to hardware-specific clock data
 *
 * Managed clk_hw_register(). Clocks registered by this function are
 * automatically clk_hw_unregister()ed on driver detach. See clk_hw_register()
 * for more information.
 */
int devm_clk_hw_register(struct device *dev, struct clk_hw *hw)
{
        struct clk_hw **hwp;
        int ret;

        hwp = devres_alloc(devm_clk_hw_release, sizeof(*hwp), GFP_KERNEL);
        if (!hwp)
                return -ENOMEM;

        ret = clk_hw_register(dev, hw);
        if (!ret) {
                *hwp = hw;
                devres_add(dev, hwp);
        } else {
                devres_free(hwp);
        }

        return ret;
}
EXPORT_SYMBOL_GPL(devm_clk_hw_register);

static int devm_clk_match(struct device *dev, void *res, void *data)
{
        struct clk *c = res;
        if (WARN_ON(!c))
                return 0;
        return c == data;
}

static int devm_clk_hw_match(struct device *dev, void *res, void *data)
{
        struct clk_hw *hw = res;

        if (WARN_ON(!hw))
                return 0;
        return hw == data;
}

/**
 * devm_clk_unregister - resource managed clk_unregister()
 * @clk: clock to unregister
 *
 * Deallocate a clock allocated with devm_clk_register(). Normally
 * this function will not need to be called and the resource management
 * code will ensure that the resource is freed.
 */
void devm_clk_unregister(struct device *dev, struct clk *clk)
{
        WARN_ON(devres_release(dev, devm_clk_release, devm_clk_match, clk));
}
EXPORT_SYMBOL_GPL(devm_clk_unregister);

/**
 * devm_clk_hw_unregister - resource managed clk_hw_unregister()
 * @dev: device that is unregistering the hardware-specific clock data
 * @hw: link to hardware-specific clock data
 *
 * Unregister a clk_hw registered with devm_clk_hw_register(). Normally
 * this function will not need to be called and the resource management
 * code will ensure that the resource is freed.
 */
void devm_clk_hw_unregister(struct device *dev, struct clk_hw *hw)
{
        WARN_ON(devres_release(dev, devm_clk_hw_release, devm_clk_hw_match,
                                hw));
}
EXPORT_SYMBOL_GPL(devm_clk_hw_unregister);

/*
 * clkdev helpers
 */

void __clk_put(struct clk *clk)
{
        struct module *owner;

        if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
                return;

        clk_prepare_lock();

        /*
         * Before calling clk_put, all calls to clk_rate_exclusive_get() from a
         * given user should be balanced with calls to clk_rate_exclusive_put()
         * and by that same consumer
         */
        if (WARN_ON(clk->exclusive_count)) {
                /* We voiced our concern, let's sanitize the situation */
                clk->core->protect_count -= (clk->exclusive_count - 1);
                clk_core_rate_unprotect(clk->core);
                clk->exclusive_count = 0;
        }

        hlist_del(&clk->clks_node);
        if (clk->min_rate > clk->core->req_rate ||
            clk->max_rate < clk->core->req_rate)
                clk_core_set_rate_nolock(clk->core, clk->core->req_rate);

        owner = clk->core->owner;
        kref_put(&clk->core->ref, __clk_release);

        clk_prepare_unlock();

        module_put(owner);

        free_clk(clk);
}

/***        clk rate change notifiers        ***/

/**
 * clk_notifier_register - add a clk rate change notifier
 * @clk: struct clk * to watch
 * @nb: struct notifier_block * with callback info
 *
 * Request notification when clk's rate changes.  This uses an SRCU
 * notifier because we want it to block and notifier unregistrations are
 * uncommon.  The callbacks associated with the notifier must not
 * re-enter into the clk framework by calling any top-level clk APIs;
 * this will cause a nested prepare_lock mutex.
 *
 * In all notification cases (pre, post and abort rate change) the original
 * clock rate is passed to the callback via struct clk_notifier_data.old_rate
 * and the new frequency is passed via struct clk_notifier_data.new_rate.
 *
 * clk_notifier_register() must be called from non-atomic context.
 * Returns -EINVAL if called with null arguments, -ENOMEM upon
 * allocation failure; otherwise, passes along the return value of
 * srcu_notifier_chain_register().
 */
int clk_notifier_register(struct clk *clk, struct notifier_block *nb)
{
        struct clk_notifier *cn;
        int ret = -ENOMEM;

        if (!clk || !nb)
                return -EINVAL;

        clk_prepare_lock();

        /* search the list of notifiers for this clk */
        list_for_each_entry(cn, &clk_notifier_list, node)
                if (cn->clk == clk)
                        break;

        /* if clk wasn't in the notifier list, allocate new clk_notifier */
        if (cn->clk != clk) {
                cn = kzalloc(sizeof(*cn), GFP_KERNEL);
                if (!cn)
                        goto out;

                cn->clk = clk;
                srcu_init_notifier_head(&cn->notifier_head);

                list_add(&cn->node, &clk_notifier_list);
        }

        ret = srcu_notifier_chain_register(&cn->notifier_head, nb);

        clk->core->notifier_count++;

out:
        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_notifier_register);

/**
 * clk_notifier_unregister - remove a clk rate change notifier
 * @clk: struct clk *
 * @nb: struct notifier_block * with callback info
 *
 * Request no further notification for changes to 'clk' and frees memory
 * allocated in clk_notifier_register.
 *
 * Returns -EINVAL if called with null arguments; otherwise, passes
 * along the return value of srcu_notifier_chain_unregister().
 */
int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb)
{
        struct clk_notifier *cn = NULL;
        int ret = -EINVAL;

        if (!clk || !nb)
                return -EINVAL;

        clk_prepare_lock();

        list_for_each_entry(cn, &clk_notifier_list, node)
                if (cn->clk == clk)
                        break;

        if (cn->clk == clk) {
                ret = srcu_notifier_chain_unregister(&cn->notifier_head, nb);

                clk->core->notifier_count--;

                /* XXX the notifier code should handle this better */
                if (!cn->notifier_head.head) {
                        srcu_cleanup_notifier_head(&cn->notifier_head);
                        list_del(&cn->node);
                        kfree(cn);
                }

        } else {
                ret = -ENOENT;
        }

        clk_prepare_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(clk_notifier_unregister);

#ifdef CONFIG_OF
/**
 * struct of_clk_provider - Clock provider registration structure
 * @link: Entry in global list of clock providers
 * @node: Pointer to device tree node of clock provider
 * @get: Get clock callback.  Returns NULL or a struct clk for the
 *       given clock specifier
 * @data: context pointer to be passed into @get callback
 */
struct of_clk_provider {
        struct list_head link;

        struct device_node *node;
        struct clk *(*get)(struct of_phandle_args *clkspec, void *data);
        struct clk_hw *(*get_hw)(struct of_phandle_args *clkspec, void *data);
        void *data;
};

static const struct of_device_id __clk_of_table_sentinel
        __used __section(__clk_of_table_end);

static LIST_HEAD(of_clk_providers);
static DEFINE_MUTEX(of_clk_mutex);

struct clk *of_clk_src_simple_get(struct of_phandle_args *clkspec,
                                     void *data)
{
        return data;
}
EXPORT_SYMBOL_GPL(of_clk_src_simple_get);

struct clk_hw *of_clk_hw_simple_get(struct of_phandle_args *clkspec, void *data)
{
        return data;
}
EXPORT_SYMBOL_GPL(of_clk_hw_simple_get);

struct clk *of_clk_src_onecell_get(struct of_phandle_args *clkspec, void *data)
{
        struct clk_onecell_data *clk_data = data;
        unsigned int idx = clkspec->args[0];

        if (idx >= clk_data->clk_num) {
                pr_err("%s: invalid clock index %u\n", __func__, idx);
                return ERR_PTR(-EINVAL);
        }

        return clk_data->clks[idx];
}
EXPORT_SYMBOL_GPL(of_clk_src_onecell_get);

struct clk_hw *
of_clk_hw_onecell_get(struct of_phandle_args *clkspec, void *data)
{
        struct clk_hw_onecell_data *hw_data = data;
        unsigned int idx = clkspec->args[0];

        if (idx >= hw_data->num) {
                pr_err("%s: invalid index %u\n", __func__, idx);
                return ERR_PTR(-EINVAL);
        }

        return hw_data->hws[idx];
}
EXPORT_SYMBOL_GPL(of_clk_hw_onecell_get);

/**
 * of_clk_add_provider() - Register a clock provider for a node
 * @np: Device node pointer associated with clock provider
 * @clk_src_get: callback for decoding clock
 * @data: context pointer for @clk_src_get callback.
 *
 * This function is *deprecated*. Use of_clk_add_hw_provider() instead.
 */
int of_clk_add_provider(struct device_node *np,
                        struct clk *(*clk_src_get)(struct of_phandle_args *clkspec,
                                                   void *data),
                        void *data)
{
        struct of_clk_provider *cp;
        int ret;

        cp = kzalloc(sizeof(*cp), GFP_KERNEL);
        if (!cp)
                return -ENOMEM;

        cp->node = of_node_get(np);
        cp->data = data;
        cp->get = clk_src_get;

        mutex_lock(&of_clk_mutex);
        list_add(&cp->link, &of_clk_providers);
        mutex_unlock(&of_clk_mutex);
        pr_debug("Added clock from %pOF\n", np);

        ret = of_clk_set_defaults(np, true);
        if (ret < 0)
                of_clk_del_provider(np);

        return ret;
}
EXPORT_SYMBOL_GPL(of_clk_add_provider);

/**
 * of_clk_add_hw_provider() - Register a clock provider for a node
 * @np: Device node pointer associated with clock provider
 * @get: callback for decoding clk_hw
 * @data: context pointer for @get callback.
 */
int of_clk_add_hw_provider(struct device_node *np,
                           struct clk_hw *(*get)(struct of_phandle_args *clkspec,
                                                 void *data),
                           void *data)
{
        struct of_clk_provider *cp;
        int ret;

        cp = kzalloc(sizeof(*cp), GFP_KERNEL);
        if (!cp)
                return -ENOMEM;

        cp->node = of_node_get(np);
        cp->data = data;
        cp->get_hw = get;

        mutex_lock(&of_clk_mutex);
        list_add(&cp->link, &of_clk_providers);
        mutex_unlock(&of_clk_mutex);
        pr_debug("Added clk_hw provider from %pOF\n", np);

        ret = of_clk_set_defaults(np, true);
        if (ret < 0)
                of_clk_del_provider(np);

        return ret;
}
EXPORT_SYMBOL_GPL(of_clk_add_hw_provider);

static void devm_of_clk_release_provider(struct device *dev, void *res)
{
        of_clk_del_provider(*(struct device_node **)res);
}

/*
 * We allow a child device to use its parent device as the clock provider node
 * for cases like MFD sub-devices where the child device driver wants to use
 * devm_*() APIs but not list the device in DT as a sub-node.
 */
static struct device_node *get_clk_provider_node(struct device *dev)
{
        struct device_node *np, *parent_np;

        np = dev->of_node;
        parent_np = dev->parent ? dev->parent->of_node : NULL;

        if (!of_find_property(np, "#clock-cells", NULL))
                if (of_find_property(parent_np, "#clock-cells", NULL))
                        np = parent_np;

        return np;
}

/**
 * devm_of_clk_add_hw_provider() - Managed clk provider node registration
 * @dev: Device acting as the clock provider (used for DT node and lifetime)
 * @get: callback for decoding clk_hw
 * @data: context pointer for @get callback
 *
 * Registers clock provider for given device's node. If the device has no DT
 * node or if the device node lacks of clock provider information (#clock-cells)
 * then the parent device's node is scanned for this information. If parent node
 * has the #clock-cells then it is used in registration. Provider is
 * automatically released at device exit.
 *
 * Return: 0 on success or an errno on failure.
 */
int devm_of_clk_add_hw_provider(struct device *dev,
                        struct clk_hw *(*get)(struct of_phandle_args *clkspec,
                                              void *data),
                        void *data)
{
        struct device_node **ptr, *np;
        int ret;

        ptr = devres_alloc(devm_of_clk_release_provider, sizeof(*ptr),
                           GFP_KERNEL);
        if (!ptr)
                return -ENOMEM;

        np = get_clk_provider_node(dev);
        ret = of_clk_add_hw_provider(np, get, data);
        if (!ret) {
                *ptr = np;
                devres_add(dev, ptr);
        } else {
                devres_free(ptr);
        }

        return ret;
}
EXPORT_SYMBOL_GPL(devm_of_clk_add_hw_provider);

/**
 * of_clk_del_provider() - Remove a previously registered clock provider
 * @np: Device node pointer associated with clock provider
 */
void of_clk_del_provider(struct device_node *np)
{
        struct of_clk_provider *cp;

        mutex_lock(&of_clk_mutex);
        list_for_each_entry(cp, &of_clk_providers, link) {
                if (cp->node == np) {
                        list_del(&cp->link);
                        of_node_put(cp->node);
                        kfree(cp);
                        break;
                }
        }
        mutex_unlock(&of_clk_mutex);
}
EXPORT_SYMBOL_GPL(of_clk_del_provider);

static int devm_clk_provider_match(struct device *dev, void *res, void *data)
{
        struct device_node **np = res;

        if (WARN_ON(!np || !*np))
                return 0;

        return *np == data;
}

/**
 * devm_of_clk_del_provider() - Remove clock provider registered using devm
 * @dev: Device to whose lifetime the clock provider was bound
 */
void devm_of_clk_del_provider(struct device *dev)
{
        int ret;
        struct device_node *np = get_clk_provider_node(dev);

        ret = devres_release(dev, devm_of_clk_release_provider,
                             devm_clk_provider_match, np);

        WARN_ON(ret);
}
EXPORT_SYMBOL(devm_of_clk_del_provider);

/*
 * Beware the return values when np is valid, but no clock provider is found.
 * If name == NULL, the function returns -ENOENT.
 * If name != NULL, the function returns -EINVAL. This is because
 * of_parse_phandle_with_args() is called even if of_property_match_string()
 * returns an error.
 */
static int of_parse_clkspec(const struct device_node *np, int index,
                            const char *name, struct of_phandle_args *out_args)
{
        int ret = -ENOENT;

        /* Walk up the tree of devices looking for a clock property that matches */
        while (np) {
                /*
                 * For named clocks, first look up the name in the
                 * "clock-names" property.  If it cannot be found, then index
                 * will be an error code and of_parse_phandle_with_args() will
                 * return -EINVAL.
                 */
                if (name)
                        index = of_property_match_string(np, "clock-names", name);
                ret = of_parse_phandle_with_args(np, "clocks", "#clock-cells",
                                                 index, out_args);
                if (!ret)
                        break;
                if (name && index >= 0)
                        break;

                /*
                 * No matching clock found on this node.  If the parent node
                 * has a "clock-ranges" property, then we can try one of its
                 * clocks.
                 */
                np = np->parent;
                if (np && !of_get_property(np, "clock-ranges", NULL))
                        break;
                index = 0;
        }

        return ret;
}

static struct clk_hw *
__of_clk_get_hw_from_provider(struct of_clk_provider *provider,
                              struct of_phandle_args *clkspec)
{
        struct clk *clk;

        if (provider->get_hw)
                return provider->get_hw(clkspec, provider->data);

        clk = provider->get(clkspec, provider->data);
        if (IS_ERR(clk))
                return ERR_CAST(clk);
        return __clk_get_hw(clk);
}

static struct clk_hw *
of_clk_get_hw_from_clkspec(struct of_phandle_args *clkspec)
{
        struct of_clk_provider *provider;
        struct clk_hw *hw = ERR_PTR(-EPROBE_DEFER);

        if (!clkspec)
                return ERR_PTR(-EINVAL);

        mutex_lock(&of_clk_mutex);
        list_for_each_entry(provider, &of_clk_providers, link) {
                if (provider->node == clkspec->np) {
                        hw = __of_clk_get_hw_from_provider(provider, clkspec);
                        if (!IS_ERR(hw))
                                break;
                }
        }
        mutex_unlock(&of_clk_mutex);

        return hw;
}

/**
 * of_clk_get_from_provider() - Lookup a clock from a clock provider
 * @clkspec: pointer to a clock specifier data structure
 *
 * This function looks up a struct clk from the registered list of clock
 * providers, an input is a clock specifier data structure as returned
 * from the of_parse_phandle_with_args() function call.
 */
struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
{
        struct clk_hw *hw = of_clk_get_hw_from_clkspec(clkspec);

        return clk_hw_create_clk(NULL, hw, NULL, __func__);
}
EXPORT_SYMBOL_GPL(of_clk_get_from_provider);

struct clk_hw *of_clk_get_hw(struct device_node *np, int index,
                             const char *con_id)
{
        int ret;
        struct clk_hw *hw;
        struct of_phandle_args clkspec;

        ret = of_parse_clkspec(np, index, con_id, &clkspec);
        if (ret)
                return ERR_PTR(ret);

        hw = of_clk_get_hw_from_clkspec(&clkspec);
        of_node_put(clkspec.np);

        return hw;
}

static struct clk *__of_clk_get(struct device_node *np,
                                int index, const char *dev_id,
                                const char *con_id)
{
        struct clk_hw *hw = of_clk_get_hw(np, index, con_id);

        return clk_hw_create_clk(NULL, hw, dev_id, con_id);
}

struct clk *of_clk_get(struct device_node *np, int index)
{
        return __of_clk_get(np, index, np->full_name, NULL);
}
EXPORT_SYMBOL(of_clk_get);

/**
 * of_clk_get_by_name() - Parse and lookup a clock referenced by a device node
 * @np: pointer to clock consumer node
 * @name: name of consumer's clock input, or NULL for the first clock reference
 *
 * This function parses the clocks and clock-names properties,
 * and uses them to look up the struct clk from the registered list of clock
 * providers.
 */
struct clk *of_clk_get_by_name(struct device_node *np, const char *name)
{
        if (!np)
                return ERR_PTR(-ENOENT);

        return __of_clk_get(np, 0, np->full_name, name);
}
EXPORT_SYMBOL(of_clk_get_by_name);

/**
 * of_clk_get_parent_count() - Count the number of clocks a device node has
 * @np: device node to count
 *
 * Returns: The number of clocks that are possible parents of this node
 */
unsigned int of_clk_get_parent_count(struct device_node *np)
{
        int count;

        count = of_count_phandle_with_args(np, "clocks", "#clock-cells");
        if (count < 0)
                return 0;

        return count;
}
EXPORT_SYMBOL_GPL(of_clk_get_parent_count);

const char *of_clk_get_parent_name(struct device_node *np, int index)
{
        struct of_phandle_args clkspec;
        struct property *prop;
        const char *clk_name;
        const __be32 *vp;
        u32 pv;
        int rc;
        int count;
        struct clk *clk;

        rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index,
                                        &clkspec);
        if (rc)
                return NULL;

        index = clkspec.args_count ? clkspec.args[0] : 0;
        count = 0;

        /* if there is an indices property, use it to transfer the index
         * specified into an array offset for the clock-output-names property.
         */
        of_property_for_each_u32(clkspec.np, "clock-indices", prop, vp, pv) {
                if (index == pv) {
                        index = count;
                        break;
                }
                count++;
        }
        /* We went off the end of 'clock-indices' without finding it */
        if (prop && !vp)
                return NULL;

        if (of_property_read_string_index(clkspec.np, "clock-output-names",
                                          index,
                                          &clk_name) < 0) {
                /*
                 * Best effort to get the name if the clock has been
                 * registered with the framework. If the clock isn't
                 * registered, we return the node name as the name of
                 * the clock as long as #clock-cells = 0.
                 */
                clk = of_clk_get_from_provider(&clkspec);
                if (IS_ERR(clk)) {
                        if (clkspec.args_count == 0)
                                clk_name = clkspec.np->name;
                        else
                                clk_name = NULL;
                } else {
                        clk_name = __clk_get_name(clk);
                        clk_put(clk);
                }
        }


        of_node_put(clkspec.np);
        return clk_name;
}
EXPORT_SYMBOL_GPL(of_clk_get_parent_name);

/**
 * of_clk_parent_fill() - Fill @parents with names of @np's parents and return
 * number of parents
 * @np: Device node pointer associated with clock provider
 * @parents: pointer to char array that hold the parents' names
 * @size: size of the @parents array
 *
 * Return: number of parents for the clock node.
 */
int of_clk_parent_fill(struct device_node *np, const char **parents,
                       unsigned int size)
{
        unsigned int i = 0;

        while (i < size && (parents[i] = of_clk_get_parent_name(np, i)) != NULL)
                i++;

        return i;
}
EXPORT_SYMBOL_GPL(of_clk_parent_fill);

struct clock_provider {
        void (*clk_init_cb)(struct device_node *);
        struct device_node *np;
        struct list_head node;
};

/*
 * This function looks for a parent clock. If there is one, then it
 * checks that the provider for this parent clock was initialized, in
 * this case the parent clock will be ready.
 */
static int parent_ready(struct device_node *np)
{
        int i = 0;

        while (true) {
                struct clk *clk = of_clk_get(np, i);

                /* this parent is ready we can check the next one */
                if (!IS_ERR(clk)) {
                        clk_put(clk);
                        i++;
                        continue;
                }

                /* at least one parent is not ready, we exit now */
                if (PTR_ERR(clk) == -EPROBE_DEFER)
                        return 0;

                /*
                 * Here we make assumption that the device tree is
                 * written correctly. So an error means that there is
                 * no more parent. As we didn't exit yet, then the
                 * previous parent are ready. If there is no clock
                 * parent, no need to wait for them, then we can
                 * consider their absence as being ready
                 */
                return 1;
        }
}

/**
 * of_clk_detect_critical() - set CLK_IS_CRITICAL flag from Device Tree
 * @np: Device node pointer associated with clock provider
 * @index: clock index
 * @flags: pointer to top-level framework flags
 *
 * Detects if the clock-critical property exists and, if so, sets the
 * corresponding CLK_IS_CRITICAL flag.
 *
 * Do not use this function. It exists only for legacy Device Tree
 * bindings, such as the one-clock-per-node style that are outdated.
 * Those bindings typically put all clock data into .dts and the Linux
 * driver has no clock data, thus making it impossible to set this flag
 * correctly from the driver. Only those drivers may call
 * of_clk_detect_critical from their setup functions.
 *
 * Return: error code or zero on success
 */
int of_clk_detect_critical(struct device_node *np,
                                          int index, unsigned long *flags)
{
        struct property *prop;
        const __be32 *cur;
        uint32_t idx;

        if (!np || !flags)
                return -EINVAL;

        of_property_for_each_u32(np, "clock-critical", prop, cur, idx)
                if (index == idx)
                        *flags |= CLK_IS_CRITICAL;

        return 0;
}

/**
 * of_clk_init() - Scan and init clock providers from the DT
 * @matches: array of compatible values and init functions for providers.
 *
 * This function scans the device tree for matching clock providers
 * and calls their initialization functions. It also does it by trying
 * to follow the dependencies.
 */
void __init of_clk_init(const struct of_device_id *matches)
{
        const struct of_device_id *match;
        struct device_node *np;
        struct clock_provider *clk_provider, *next;
        bool is_init_done;
        bool force = false;
        LIST_HEAD(clk_provider_list);

        if (!matches)
                matches = &__clk_of_table;

        /* First prepare the list of the clocks providers */
        for_each_matching_node_and_match(np, matches, &match) {
                struct clock_provider *parent;

                if (!of_device_is_available(np))
                        continue;

                parent = kzalloc(sizeof(*parent), GFP_KERNEL);
                if (!parent) {
                        list_for_each_entry_safe(clk_provider, next,
                                                 &clk_provider_list, node) {
                                list_del(&clk_provider->node);
                                of_node_put(clk_provider->np);
                                kfree(clk_provider);
                        }
                        of_node_put(np);
                        return;
                }

                parent->clk_init_cb = match->data;
                parent->np = of_node_get(np);
                list_add_tail(&parent->node, &clk_provider_list);
        }

        while (!list_empty(&clk_provider_list)) {
                is_init_done = false;
                list_for_each_entry_safe(clk_provider, next,
                                        &clk_provider_list, node) {
                        if (force || parent_ready(clk_provider->np)) {

                                /* Don't populate platform devices */
                                of_node_set_flag(clk_provider->np,
                                                 OF_POPULATED);

                                clk_provider->clk_init_cb(clk_provider->np);
                                of_clk_set_defaults(clk_provider->np, true);

                                list_del(&clk_provider->node);
                                of_node_put(clk_provider->np);
                                kfree(clk_provider);
                                is_init_done = true;
                        }
                }

                /*
                 * We didn't manage to initialize any of the
                 * remaining providers during the last loop, so now we
                 * initialize all the remaining ones unconditionally
                 * in case the clock parent was not mandatory
                 */
                if (!is_init_done)
                        force = true;
        }
}
#endif