LIST_HEAD(opp_tables);
/* Lock to allow exclusive modification to the device and opp lists */
DEFINE_MUTEX(opp_table_lock);
+/* Flag indicating that opp_tables list is being updated at the moment */
+static bool opp_tables_busy;
-static struct opp_device *_find_opp_dev(const struct device *dev,
- struct opp_table *opp_table)
+static bool _find_opp_dev(const struct device *dev, struct opp_table *opp_table)
{
struct opp_device *opp_dev;
+ bool found = false;
+ mutex_lock(&opp_table->lock);
list_for_each_entry(opp_dev, &opp_table->dev_list, node)
- if (opp_dev->dev == dev)
- return opp_dev;
+ if (opp_dev->dev == dev) {
+ found = true;
+ break;
+ }
- return NULL;
+ mutex_unlock(&opp_table->lock);
+ return found;
}
static struct opp_table *_find_opp_table_unlocked(struct device *dev)
{
struct opp_table *opp_table;
- bool found;
list_for_each_entry(opp_table, &opp_tables, node) {
- mutex_lock(&opp_table->lock);
- found = !!_find_opp_dev(dev, opp_table);
- mutex_unlock(&opp_table->lock);
-
- if (found) {
+ if (_find_opp_dev(dev, opp_table)) {
_get_opp_table_kref(opp_table);
-
return opp_table;
}
}
kfree(opp_dev);
}
-static struct opp_device *_add_opp_dev_unlocked(const struct device *dev,
- struct opp_table *opp_table)
+struct opp_device *_add_opp_dev(const struct device *dev,
+ struct opp_table *opp_table)
{
struct opp_device *opp_dev;
/* Initialize opp-dev */
opp_dev->dev = dev;
+ mutex_lock(&opp_table->lock);
list_add(&opp_dev->node, &opp_table->dev_list);
+ mutex_unlock(&opp_table->lock);
/* Create debugfs entries for the opp_table */
opp_debug_register(opp_dev, opp_table);
return opp_dev;
}
-struct opp_device *_add_opp_dev(const struct device *dev,
- struct opp_table *opp_table)
-{
- struct opp_device *opp_dev;
-
- mutex_lock(&opp_table->lock);
- opp_dev = _add_opp_dev_unlocked(dev, opp_table);
- mutex_unlock(&opp_table->lock);
-
- return opp_dev;
-}
-
static struct opp_table *_allocate_opp_table(struct device *dev, int index)
{
struct opp_table *opp_table;
INIT_LIST_HEAD(&opp_table->opp_list);
kref_init(&opp_table->kref);
- /* Secure the device table modification */
- list_add(&opp_table->node, &opp_tables);
return opp_table;
err:
kref_get(&opp_table->kref);
}
-static struct opp_table *_opp_get_opp_table(struct device *dev, int index)
+/*
+ * We need to make sure that the OPP table for a device doesn't get added twice,
+ * if this routine gets called in parallel with the same device pointer.
+ *
+ * The simplest way to enforce that is to perform everything (find existing
+ * table and if not found, create a new one) under the opp_table_lock, so only
+ * one creator gets access to the same. But that expands the critical section
+ * under the lock and may end up causing circular dependencies with frameworks
+ * like debugfs, interconnect or clock framework as they may be direct or
+ * indirect users of OPP core.
+ *
+ * And for that reason we have to go for a bit tricky implementation here, which
+ * uses the opp_tables_busy flag to indicate if another creator is in the middle
+ * of adding an OPP table and others should wait for it to finish.
+ */
+struct opp_table *_add_opp_table_indexed(struct device *dev, int index)
{
struct opp_table *opp_table;
- /* Hold our table modification lock here */
+again:
mutex_lock(&opp_table_lock);
opp_table = _find_opp_table_unlocked(dev);
if (!IS_ERR(opp_table))
goto unlock;
+ /*
+ * The opp_tables list or an OPP table's dev_list is getting updated by
+ * another user, wait for it to finish.
+ */
+ if (unlikely(opp_tables_busy)) {
+ mutex_unlock(&opp_table_lock);
+ cpu_relax();
+ goto again;
+ }
+
+ opp_tables_busy = true;
opp_table = _managed_opp(dev, index);
+
+ /* Drop the lock to reduce the size of critical section */
+ mutex_unlock(&opp_table_lock);
+
if (opp_table) {
- if (!_add_opp_dev_unlocked(dev, opp_table)) {
+ if (!_add_opp_dev(dev, opp_table)) {
dev_pm_opp_put_opp_table(opp_table);
opp_table = ERR_PTR(-ENOMEM);
}
- goto unlock;
+
+ mutex_lock(&opp_table_lock);
+ } else {
+ opp_table = _allocate_opp_table(dev, index);
+
+ mutex_lock(&opp_table_lock);
+ if (!IS_ERR(opp_table))
+ list_add(&opp_table->node, &opp_tables);
}
- opp_table = _allocate_opp_table(dev, index);
+ opp_tables_busy = false;
unlock:
mutex_unlock(&opp_table_lock);
return opp_table;
}
-struct opp_table *dev_pm_opp_get_opp_table(struct device *dev)
+struct opp_table *_add_opp_table(struct device *dev)
{
- return _opp_get_opp_table(dev, 0);
+ return _add_opp_table_indexed(dev, 0);
}
-EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_table);
-struct opp_table *dev_pm_opp_get_opp_table_indexed(struct device *dev,
- int index)
+struct opp_table *dev_pm_opp_get_opp_table(struct device *dev)
{
- return _opp_get_opp_table(dev, index);
+ return _find_opp_table(dev);
}
+EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_table);
static void _opp_table_kref_release(struct kref *kref)
{
struct opp_device *opp_dev, *temp;
int i;
+ /* Drop the lock as soon as we can */
+ list_del(&opp_table->node);
+ mutex_unlock(&opp_table_lock);
+
_of_clear_opp_table(opp_table);
/* Release clk */
mutex_destroy(&opp_table->genpd_virt_dev_lock);
mutex_destroy(&opp_table->lock);
- list_del(&opp_table->node);
kfree(opp_table);
-
- mutex_unlock(&opp_table_lock);
}
void dev_pm_opp_put_opp_table(struct opp_table *opp_table)
kfree(opp);
}
-static void _opp_kref_release(struct dev_pm_opp *opp,
- struct opp_table *opp_table)
+static void _opp_kref_release(struct kref *kref)
{
+ struct dev_pm_opp *opp = container_of(kref, struct dev_pm_opp, kref);
+ struct opp_table *opp_table = opp->opp_table;
+
+ list_del(&opp->node);
+ mutex_unlock(&opp_table->lock);
+
/*
* Notify the changes in the availability of the operable
* frequency/voltage list.
blocking_notifier_call_chain(&opp_table->head, OPP_EVENT_REMOVE, opp);
_of_opp_free_required_opps(opp_table, opp);
opp_debug_remove_one(opp);
- list_del(&opp->node);
kfree(opp);
}
-static void _opp_kref_release_unlocked(struct kref *kref)
-{
- struct dev_pm_opp *opp = container_of(kref, struct dev_pm_opp, kref);
- struct opp_table *opp_table = opp->opp_table;
-
- _opp_kref_release(opp, opp_table);
-}
-
-static void _opp_kref_release_locked(struct kref *kref)
-{
- struct dev_pm_opp *opp = container_of(kref, struct dev_pm_opp, kref);
- struct opp_table *opp_table = opp->opp_table;
-
- _opp_kref_release(opp, opp_table);
- mutex_unlock(&opp_table->lock);
-}
-
void dev_pm_opp_get(struct dev_pm_opp *opp)
{
kref_get(&opp->kref);
void dev_pm_opp_put(struct dev_pm_opp *opp)
{
- kref_put_mutex(&opp->kref, _opp_kref_release_locked,
- &opp->opp_table->lock);
+ kref_put_mutex(&opp->kref, _opp_kref_release, &opp->opp_table->lock);
}
EXPORT_SYMBOL_GPL(dev_pm_opp_put);
-static void dev_pm_opp_put_unlocked(struct dev_pm_opp *opp)
-{
- kref_put(&opp->kref, _opp_kref_release_unlocked);
-}
-
/**
* dev_pm_opp_remove() - Remove an OPP from OPP table
* @dev: device for which we do this operation
}
EXPORT_SYMBOL_GPL(dev_pm_opp_remove);
+static struct dev_pm_opp *_opp_get_next(struct opp_table *opp_table,
+ bool dynamic)
+{
+ struct dev_pm_opp *opp = NULL, *temp;
+
+ mutex_lock(&opp_table->lock);
+ list_for_each_entry(temp, &opp_table->opp_list, node) {
+ if (dynamic == temp->dynamic) {
+ opp = temp;
+ break;
+ }
+ }
+
+ mutex_unlock(&opp_table->lock);
+ return opp;
+}
+
bool _opp_remove_all_static(struct opp_table *opp_table)
{
- struct dev_pm_opp *opp, *tmp;
- bool ret = true;
+ struct dev_pm_opp *opp;
mutex_lock(&opp_table->lock);
if (!opp_table->parsed_static_opps) {
- ret = false;
- goto unlock;
+ mutex_unlock(&opp_table->lock);
+ return false;
}
- if (--opp_table->parsed_static_opps)
- goto unlock;
-
- list_for_each_entry_safe(opp, tmp, &opp_table->opp_list, node) {
- if (!opp->dynamic)
- dev_pm_opp_put_unlocked(opp);
+ if (--opp_table->parsed_static_opps) {
+ mutex_unlock(&opp_table->lock);
+ return true;
}
-unlock:
mutex_unlock(&opp_table->lock);
- return ret;
+ /*
+ * Can't remove the OPP from under the lock, debugfs removal needs to
+ * happen lock less to avoid circular dependency issues.
+ */
+ while ((opp = _opp_get_next(opp_table, false)))
+ dev_pm_opp_put(opp);
+
+ return true;
}
/**
void dev_pm_opp_remove_all_dynamic(struct device *dev)
{
struct opp_table *opp_table;
- struct dev_pm_opp *opp, *temp;
+ struct dev_pm_opp *opp;
int count = 0;
opp_table = _find_opp_table(dev);
if (IS_ERR(opp_table))
return;
- mutex_lock(&opp_table->lock);
- list_for_each_entry_safe(opp, temp, &opp_table->opp_list, node) {
- if (opp->dynamic) {
- dev_pm_opp_put_unlocked(opp);
- count++;
- }
+ /*
+ * Can't remove the OPP from under the lock, debugfs removal needs to
+ * happen lock less to avoid circular dependency issues.
+ */
+ while ((opp = _opp_get_next(opp_table, true))) {
+ dev_pm_opp_put(opp);
+ count++;
}
- mutex_unlock(&opp_table->lock);
/* Drop the references taken by dev_pm_opp_add() */
while (count--)
{
struct opp_table *opp_table;
- opp_table = dev_pm_opp_get_opp_table(dev);
+ opp_table = _add_opp_table(dev);
if (IS_ERR(opp_table))
return opp_table;
{
struct opp_table *opp_table;
- opp_table = dev_pm_opp_get_opp_table(dev);
+ opp_table = _add_opp_table(dev);
if (IS_ERR(opp_table))
return opp_table;
struct regulator *reg;
int ret, i;
- opp_table = dev_pm_opp_get_opp_table(dev);
+ opp_table = _add_opp_table(dev);
if (IS_ERR(opp_table))
return opp_table;
struct opp_table *opp_table;
int ret;
- opp_table = dev_pm_opp_get_opp_table(dev);
+ opp_table = _add_opp_table(dev);
if (IS_ERR(opp_table))
return opp_table;
if (!set_opp)
return ERR_PTR(-EINVAL);
- opp_table = dev_pm_opp_get_opp_table(dev);
- if (!IS_ERR(opp_table))
+ opp_table = _add_opp_table(dev);
+ if (IS_ERR(opp_table))
return opp_table;
/* This should be called before OPPs are initialized */
int index = 0, ret = -EINVAL;
const char **name = names;
- opp_table = dev_pm_opp_get_opp_table(dev);
+ opp_table = _add_opp_table(dev);
if (IS_ERR(opp_table))
return opp_table;
struct opp_table *opp_table;
int ret;
- opp_table = dev_pm_opp_get_opp_table(dev);
+ opp_table = _add_opp_table(dev);
if (IS_ERR(opp_table))
return PTR_ERR(opp_table);
projects / linux-2.6-microblaze.git / blobdiff