Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 4241 insertions, 0 deletions

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
new file mode 100644
index 000000000..32606d109
--- /dev/null
+++ b/drivers/clk/clk.c
@@ -0,0 +1,4241 @@
+/*
+ * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
+ * Copyright (C) 2011-2012 Linaro Ltd <mturquette@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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);
+
+static struct hlist_head *all_lists[] = {
+	&clk_root_list,
+	&clk_orphan_list,
+	NULL,
+};
+
+/***    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;
+	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;
+	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 = 0;
+
+	if (!core->dev)
+		return 0;
+
+	ret = pm_runtime_get_sync(core->dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(core->dev);
+		return ret;
+	}
+	return 0;
+}
+
+static void clk_pm_runtime_put(struct clk_core *core)
+{
+	if (!core->dev)
+		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->dev) {
+		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->dev)
+		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)
+{
+	unsigned long ret;
+
+	if (!core) {
+		ret = 0;
+		goto out;
+	}
+
+	ret = core->rate;
+
+	if (!core->num_parents)
+		goto out;
+
+	if (!core->parent)
+		ret = 0;
+
+out:
+	return ret;
+}
+
+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);
+}
+
+bool clk_hw_rate_is_protected(const struct clk_hw *hw)
+{
+	return clk_core_rate_is_protected(hw->core);
+}
+
+bool clk_hw_is_enabled(const struct clk_hw *hw)
+{
+	return clk_core_is_enabled(hw->core);
+}
+
+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);
+}
+
+static bool clk_core_check_boundaries(struct clk_core *core,
+				      unsigned long min_rate,
+				      unsigned long max_rate)
+{
+	struct clk *user;
+
+	lockdep_assert_held(&prepare_lock);
+
+	if (min_rate > core->max_rate || max_rate < core->min_rate)
+		return false;
+
+	hlist_for_each_entry(user, &core->clks, clks_node)
+		if (min_rate > user->max_rate || max_rate < user->min_rate)
+			return false;
+
+	return true;
+}
+
+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);
+
+/*
+ * 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.
+ */
+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_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 (clk_core_get_parent_by_index(core, 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;
+
+	if (!clk_core_check_boundaries(clk->core, min, max)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	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;
+		}
+	}
+
+out:
+	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 *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;
+
+		ret = clk_core_prepare(core);
+		if (ret)
+			goto out;
+
+		flags = clk_enable_lock();
+		ret = clk_core_enable(core);
+		clk_enable_unlock(flags);
+		if (ret) {
+			clk_core_unprepare(core);
+			goto out;
+		}
+	}
+
+	/*
+	 * 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:
+	if (ret)
+		hlist_del_init(&core->child_node);
+
+	clk_prepare_unlock();
+
+	if (!ret)
+		clk_debug_register(core);
+
+	return ret;
+}
+
+struct clk *__clk_create_clk(struct clk_hw *hw, const char *dev_id,
+			     const char *con_id)
+{
+	struct clk *clk;
+
+	/* This is to allow this function to be chained to others */
+	if (IS_ERR_OR_NULL(hw))
+		return ERR_CAST(hw);
+
+	clk = kzalloc(sizeof(*clk), GFP_KERNEL);
+	if (!clk)
+		return ERR_PTR(-ENOMEM);
+
+	clk->core = hw->core;
+	clk->dev_id = dev_id;
+	clk->con_id = kstrdup_const(con_id, GFP_KERNEL);
+	clk->max_rate = ULONG_MAX;
+
+	clk_prepare_lock();
+	hlist_add_head(&clk->clks_node, &hw->core->clks);
+	clk_prepare_unlock();
+
+	return clk;
+}
+
+/* keep in sync with __clk_put */
+void __clk_free_clk(struct clk *clk)
+{
+	clk_prepare_lock();
+	hlist_del(&clk->clks_node);
+	clk_prepare_unlock();
+
+	kfree_const(clk->con_id);
+	kfree(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 primary interface for populating the clock tree with new
+ * clock nodes.  It 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->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);
+
+	hw->clk = __clk_create_clk(hw, NULL, NULL);
+	if (IS_ERR(hw->clk)) {
+		ret = PTR_ERR(hw->clk);
+		goto fail_parents;
+	}
+
+	ret = __clk_core_init(core);
+	if (!ret)
+		return hw->clk;
+
+	__clk_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,
+};
+
+static void clk_core_evict_parent_cache_subtree(struct clk_core *root,
+						struct clk_core *target)
+{
+	int i;
+	struct clk_core *child;
+
+	for (i = 0; i < root->num_parents; i++)
+		if (root->parents[i] == target)
+			root->parents[i] = NULL;
+
+	hlist_for_each_entry(child, &root->children, child_node)
+		clk_core_evict_parent_cache_subtree(child, target);
+}
+
+/* Remove this clk from all parent caches */
+static void clk_core_evict_parent_cache(struct clk_core *core)
+{
+	struct hlist_head **lists;
+	struct clk_core *root;
+
+	lockdep_assert_held(&prepare_lock);
+
+	for (lists = all_lists; *lists; lists++)
+		hlist_for_each_entry(root, *lists, child_node)
+			clk_core_evict_parent_cache_subtree(root, core);
+
+}
+
+/**
+ * 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);
+	}
+
+	clk_core_evict_parent_cache(clk->core);
+
+	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(). 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
+ */
+int __clk_get(struct clk *clk)
+{
+	struct clk_core *core = !clk ? NULL : clk->core;
+
+	if (core) {
+		if (!try_module_get(core->owner))
+			return 0;
+
+		kref_get(&core->ref);
+	}
+	return 1;
+}
+
+/* keep in sync with __clk_free_clk */
+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);
+
+	kfree_const(clk->con_id);
+	kfree(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)
+			goto found;
+
+	/* if clk wasn't in the notifier list, allocate new clk_notifier */
+	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);
+
+found:
+	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;
+	int ret = -ENOENT;
+
+	if (!clk || !nb)
+		return -EINVAL;
+
+	clk_prepare_lock();
+
+	list_for_each_entry(cn, &clk_notifier_list, node) {
+		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);
+			}
+			break;
+		}
+	}
+
+	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.
+ */
+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);
+}
+
+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 = dev->of_node;
+	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;
+}
+
+void devm_of_clk_del_provider(struct device *dev)
+{
+	int ret;
+
+	ret = devres_release(dev, devm_of_clk_release_provider,
+			     devm_clk_provider_match, dev->of_node);
+
+	WARN_ON(ret);
+}
+EXPORT_SYMBOL(devm_of_clk_del_provider);
+
+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);
+}
+
+struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec,
+				       const char *dev_id, const char *con_id)
+{
+	struct of_clk_provider *provider;
+	struct clk *clk = ERR_PTR(-EPROBE_DEFER);
+	struct clk_hw *hw;
+
+	if (!clkspec)
+		return ERR_PTR(-EINVAL);
+
+	/* Check if we have such a provider in our array */
+	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);
+			clk = __clk_create_clk(hw, dev_id, con_id);
+		}
+
+		if (!IS_ERR(clk)) {
+			if (!__clk_get(clk)) {
+				__clk_free_clk(clk);
+				clk = ERR_PTR(-ENOENT);
+			}
+
+			break;
+		}
+	}
+	mutex_unlock(&of_clk_mutex);
+
+	return clk;
+}
+
+/**
+ * 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)
+{
+	return __of_clk_get_from_provider(clkspec, NULL, __func__);
+}
+EXPORT_SYMBOL_GPL(of_clk_get_from_provider);
+
+/**
+ * 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