seq_printf(s, "%*s%-*s %-11d %-12d %-10lu",
level * 3 + 1, "",
30 - level * 3, c->name,
- c->enable_count, c->prepare_count, c->rate);
+ c->enable_count, c->prepare_count, clk_get_rate(c));
seq_printf(s, "\n");
}
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, "\"rate\": %lu", c->rate);
+ seq_printf(s, "\"rate\": %lu", clk_get_rate(c));
}
static void clk_dump_subtree(struct seq_file *s, struct clk *c, int level)
return 0;
}
-late_initcall(clk_disable_unused);
+late_initcall_sync(clk_disable_unused);
/*** helper functions ***/
clk_prepare_lock();
/* bail early if nothing to do */
- if (rate == clk->rate)
+ if (rate == clk_get_rate(clk))
goto out;
if ((clk->flags & CLK_SET_RATE_GATE) && clk->prepare_count) {
unsigned long flags;
int ret = 0;
struct clk *old_parent = clk->parent;
- bool migrated_enable = false;
- /* migrate prepare */
- if (clk->prepare_count)
+ /*
+ * 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.
+ */
+ if (clk->prepare_count) {
__clk_prepare(parent);
-
- flags = clk_enable_lock();
-
- /* migrate enable */
- if (clk->enable_count) {
- __clk_enable(parent);
- migrated_enable = true;
+ clk_enable(parent);
+ clk_enable(clk);
}
/* update the clk tree topology */
+ flags = clk_enable_lock();
clk_reparent(clk, parent);
-
clk_enable_unlock(flags);
/* change clock input source */
ret = clk->ops->set_parent(clk->hw, p_index);
if (ret) {
- /*
- * The error handling is tricky due to that we need to release
- * the spinlock while issuing the .set_parent callback. This
- * means the new parent might have been enabled/disabled in
- * between, which must be considered when doing rollback.
- */
flags = clk_enable_lock();
-
clk_reparent(clk, old_parent);
-
- if (migrated_enable && clk->enable_count) {
- __clk_disable(parent);
- } else if (migrated_enable && (clk->enable_count == 0)) {
- __clk_disable(old_parent);
- } else if (!migrated_enable && clk->enable_count) {
- __clk_disable(parent);
- __clk_enable(old_parent);
- }
-
clk_enable_unlock(flags);
- if (clk->prepare_count)
+ if (clk->prepare_count) {
+ clk_disable(clk);
+ clk_disable(parent);
__clk_unprepare(parent);
-
+ }
return ret;
}
- /* clean up enable for old parent if migration was done */
- if (migrated_enable) {
- flags = clk_enable_lock();
- __clk_disable(old_parent);
- clk_enable_unlock(flags);
- }
-
- /* clean up prepare for old parent if migration was done */
- if (clk->prepare_count)
+ /*
+ * Finish the migration of prepare state and undo the changes done
+ * for preventing a race with clk_enable().
+ */
+ if (clk->prepare_count) {
+ clk_disable(clk);
+ clk_disable(old_parent);
__clk_unprepare(old_parent);
+ }
/* update debugfs with new clk tree topology */
clk_debug_reparent(clk, parent);
* @clk: the mux clk whose input we are switching
* @parent: the new input to clk
*
- * Re-parent clk to use parent as it's new input source. If clk has the
- * CLK_SET_PARENT_GATE flag set then clk must be gated for this
- * operation to succeed. 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.
+ * 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)
{
}
/* propagate PRE_RATE_CHANGE notifications */
- if (clk->notifier_count)
- ret = __clk_speculate_rates(clk, p_rate);
+ ret = __clk_speculate_rates(clk, p_rate);
/* abort if a driver objects */
if (ret & NOTIFY_STOP_MASK)
projects / linux-2.6-microblaze.git / blobdiff