clk.c 35.1 KB
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/*
 * 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/clk.txt
 */

#include <linux/clk-private.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>

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

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

/***        debugfs support        ***/

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

static struct dentry *rootdir;
static struct dentry *orphandir;
static int inited = 0;

/* caller must hold prepare_lock */
static int clk_debug_create_one(struct clk *clk, struct dentry *pdentry)
{
	struct dentry *d;
	int ret = -ENOMEM;

	if (!clk || !pdentry) {
		ret = -EINVAL;
		goto out;
	}

	d = debugfs_create_dir(clk->name, pdentry);
	if (!d)
		goto out;

	clk->dentry = d;

	d = debugfs_create_u32("clk_rate", S_IRUGO, clk->dentry,
			(u32 *)&clk->rate);
	if (!d)
		goto err_out;

	d = debugfs_create_x32("clk_flags", S_IRUGO, clk->dentry,
			(u32 *)&clk->flags);
	if (!d)
		goto err_out;

	d = debugfs_create_u32("clk_prepare_count", S_IRUGO, clk->dentry,
			(u32 *)&clk->prepare_count);
	if (!d)
		goto err_out;

	d = debugfs_create_u32("clk_enable_count", S_IRUGO, clk->dentry,
			(u32 *)&clk->enable_count);
	if (!d)
		goto err_out;

	d = debugfs_create_u32("clk_notifier_count", S_IRUGO, clk->dentry,
			(u32 *)&clk->notifier_count);
	if (!d)
		goto err_out;

	ret = 0;
	goto out;

err_out:
	debugfs_remove(clk->dentry);
out:
	return ret;
}

/* caller must hold prepare_lock */
static int clk_debug_create_subtree(struct clk *clk, struct dentry *pdentry)
{
	struct clk *child;
	struct hlist_node *tmp;
	int ret = -EINVAL;;

	if (!clk || !pdentry)
		goto out;

	ret = clk_debug_create_one(clk, pdentry);

	if (ret)
		goto out;

	hlist_for_each_entry(child, tmp, &clk->children, child_node)
		clk_debug_create_subtree(child, clk->dentry);

	ret = 0;
out:
	return ret;
}

/**
 * clk_debug_register - add a clk node to the debugfs clk tree
 * @clk: the clk being added to the debugfs clk tree
 *
 * Dynamically adds a clk to the debugfs clk tree if debugfs has been
 * initialized.  Otherwise it bails out early since the debugfs clk tree
 * will be created lazily by clk_debug_init as part of a late_initcall.
 *
 * Caller must hold prepare_lock.  Only clk_init calls this function (so
 * far) so this is taken care.
 */
static int clk_debug_register(struct clk *clk)
{
	struct clk *parent;
	struct dentry *pdentry;
	int ret = 0;

	if (!inited)
		goto out;

	parent = clk->parent;

	/*
	 * Check to see if a clk is a root clk.  Also check that it is
	 * safe to add this clk to debugfs
	 */
	if (!parent)
		if (clk->flags & CLK_IS_ROOT)
			pdentry = rootdir;
		else
			pdentry = orphandir;
	else
		if (parent->dentry)
			pdentry = parent->dentry;
		else
			goto out;

	ret = clk_debug_create_subtree(clk, pdentry);

out:
	return ret;
}

/**
 * clk_debug_init - lazily create the debugfs clk tree visualization
 *
 * clks are often initialized very early during boot before memory can
 * be dynamically allocated and well before debugfs is setup.
 * clk_debug_init walks the clk tree hierarchy while holding
 * prepare_lock and creates the topology as part of a late_initcall,
 * thus insuring that clks initialized very early will still be
 * represented in the debugfs clk tree.  This function should only be
 * called once at boot-time, and all other clks added dynamically will
 * be done so with clk_debug_register.
 */
static int __init clk_debug_init(void)
{
	struct clk *clk;
	struct hlist_node *tmp;

	rootdir = debugfs_create_dir("clk", NULL);

	if (!rootdir)
		return -ENOMEM;

	orphandir = debugfs_create_dir("orphans", rootdir);

	if (!orphandir)
		return -ENOMEM;

	mutex_lock(&prepare_lock);

	hlist_for_each_entry(clk, tmp, &clk_root_list, child_node)
		clk_debug_create_subtree(clk, rootdir);

	hlist_for_each_entry(clk, tmp, &clk_orphan_list, child_node)
		clk_debug_create_subtree(clk, orphandir);

	inited = 1;

	mutex_unlock(&prepare_lock);

	return 0;
}
late_initcall(clk_debug_init);
#else
static inline int clk_debug_register(struct clk *clk) { return 0; }
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#endif
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#ifdef CONFIG_COMMON_CLK_DISABLE_UNUSED
/* caller must hold prepare_lock */
static void clk_disable_unused_subtree(struct clk *clk)
{
	struct clk *child;
	struct hlist_node *tmp;
	unsigned long flags;

	if (!clk)
		goto out;

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

	spin_lock_irqsave(&enable_lock, flags);

	if (clk->enable_count)
		goto unlock_out;

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

	if (__clk_is_enabled(clk) && clk->ops->disable)
		clk->ops->disable(clk->hw);

unlock_out:
	spin_unlock_irqrestore(&enable_lock, flags);

out:
	return;
}

static int clk_disable_unused(void)
{
	struct clk *clk;
	struct hlist_node *tmp;

	mutex_lock(&prepare_lock);

	hlist_for_each_entry(clk, tmp, &clk_root_list, child_node)
		clk_disable_unused_subtree(clk);

	hlist_for_each_entry(clk, tmp, &clk_orphan_list, child_node)
		clk_disable_unused_subtree(clk);

	mutex_unlock(&prepare_lock);

	return 0;
}
late_initcall(clk_disable_unused);
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#endif
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/***    helper functions   ***/

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

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

inline u8 __clk_get_num_parents(struct clk *clk)
{
	return !clk ? -EINVAL : clk->num_parents;
}

inline struct clk *__clk_get_parent(struct clk *clk)
{
	return !clk ? NULL : clk->parent;
}

inline int __clk_get_enable_count(struct clk *clk)
{
	return !clk ? -EINVAL : clk->enable_count;
}

inline int __clk_get_prepare_count(struct clk *clk)
{
	return !clk ? -EINVAL : clk->prepare_count;
}

unsigned long __clk_get_rate(struct clk *clk)
{
	unsigned long ret;

	if (!clk) {
		ret = -EINVAL;
		goto out;
	}

	ret = clk->rate;

	if (clk->flags & CLK_IS_ROOT)
		goto out;

	if (!clk->parent)
		ret = -ENODEV;

out:
	return ret;
}

inline unsigned long __clk_get_flags(struct clk *clk)
{
	return !clk ? -EINVAL : clk->flags;
}

int __clk_is_enabled(struct clk *clk)
{
	int ret;

	if (!clk)
		return -EINVAL;

	/*
	 * .is_enabled is only mandatory for clocks that gate
	 * fall back to software usage counter if .is_enabled is missing
	 */
	if (!clk->ops->is_enabled) {
		ret = clk->enable_count ? 1 : 0;
		goto out;
	}

	ret = clk->ops->is_enabled(clk->hw);
out:
	return ret;
}

static struct clk *__clk_lookup_subtree(const char *name, struct clk *clk)
{
	struct clk *child;
	struct clk *ret;
	struct hlist_node *tmp;

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

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

	return NULL;
}

struct clk *__clk_lookup(const char *name)
{
	struct clk *root_clk;
	struct clk *ret;
	struct hlist_node *tmp;

	if (!name)
		return NULL;

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

	return NULL;
}

/***        clk api        ***/

void __clk_unprepare(struct clk *clk)
{
	if (!clk)
		return;

	if (WARN_ON(clk->prepare_count == 0))
		return;

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

	WARN_ON(clk->enable_count > 0);

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

	__clk_unprepare(clk->parent);
}

/**
 * clk_unprepare - undo preparation of a clock source
 * @clk: the clk being unprepare
 *
 * 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)
{
	mutex_lock(&prepare_lock);
	__clk_unprepare(clk);
	mutex_unlock(&prepare_lock);
}
EXPORT_SYMBOL_GPL(clk_unprepare);

int __clk_prepare(struct clk *clk)
{
	int ret = 0;

	if (!clk)
		return 0;

	if (clk->prepare_count == 0) {
		ret = __clk_prepare(clk->parent);
		if (ret)
			return ret;

		if (clk->ops->prepare) {
			ret = clk->ops->prepare(clk->hw);
			if (ret) {
				__clk_unprepare(clk->parent);
				return ret;
			}
		}
	}

	clk->prepare_count++;

	return 0;
}

/**
 * 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)
{
	int ret;

	mutex_lock(&prepare_lock);
	ret = __clk_prepare(clk);
	mutex_unlock(&prepare_lock);

	return ret;
}
EXPORT_SYMBOL_GPL(clk_prepare);

static void __clk_disable(struct clk *clk)
{
	if (!clk)
		return;

	if (WARN_ON(clk->enable_count == 0))
		return;

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

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

	__clk_disable(clk->parent);
}

/**
 * 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)
{
	unsigned long flags;

	spin_lock_irqsave(&enable_lock, flags);
	__clk_disable(clk);
	spin_unlock_irqrestore(&enable_lock, flags);
}
EXPORT_SYMBOL_GPL(clk_disable);

static int __clk_enable(struct clk *clk)
{
	int ret = 0;

	if (!clk)
		return 0;

	if (WARN_ON(clk->prepare_count == 0))
		return -ESHUTDOWN;

	if (clk->enable_count == 0) {
		ret = __clk_enable(clk->parent);

		if (ret)
			return ret;

		if (clk->ops->enable) {
			ret = clk->ops->enable(clk->hw);
			if (ret) {
				__clk_disable(clk->parent);
				return ret;
			}
		}
	}

	clk->enable_count++;
	return 0;
}

/**
 * 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)
{
	unsigned long flags;
	int ret;

	spin_lock_irqsave(&enable_lock, flags);
	ret = __clk_enable(clk);
	spin_unlock_irqrestore(&enable_lock, flags);

	return ret;
}
EXPORT_SYMBOL_GPL(clk_enable);

/**
 * clk_get_rate - return the rate of clk
 * @clk: the clk whose rate is being returned
 *
 * Simply returns the cached rate of the clk.  Does not query the hardware.  If
 * clk is NULL then returns -EINVAL.
 */
unsigned long clk_get_rate(struct clk *clk)
{
	unsigned long rate;

	mutex_lock(&prepare_lock);
	rate = __clk_get_rate(clk);
	mutex_unlock(&prepare_lock);

	return rate;
}
EXPORT_SYMBOL_GPL(clk_get_rate);

/**
 * __clk_round_rate - round the given rate for a clk
 * @clk: round the rate of this clock
 *
 * Caller must hold prepare_lock.  Useful for clk_ops such as .set_rate
 */
unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
{
	unsigned long unused;

	if (!clk)
		return -EINVAL;

	if (!clk->ops->round_rate)
		return clk->rate;

	if (clk->flags & CLK_SET_RATE_PARENT)
		return clk->ops->round_rate(clk->hw, rate, &unused);
	else
		return clk->ops->round_rate(clk->hw, rate, NULL);
}

/**
 * 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)
{
	unsigned long ret;

	mutex_lock(&prepare_lock);
	ret = __clk_round_rate(clk, rate);
	mutex_unlock(&prepare_lock);

	return ret;
}
EXPORT_SYMBOL_GPL(clk_round_rate);

/**
 * __clk_notify - call clk notifier chain
 * @clk: struct 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 *clk, 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.clk = clk;
	cnd.old_rate = old_rate;
	cnd.new_rate = new_rate;

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

	return ret;
}

/**
 * __clk_recalc_rates
 * @clk: 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 it's parent.
 *
 * clk_recalc_rates also propagates the POST_RATE_CHANGE notification,
 * if necessary.
 *
 * Caller must hold prepare_lock.
 */
static void __clk_recalc_rates(struct clk *clk, unsigned long msg)
{
	unsigned long old_rate;
	unsigned long parent_rate = 0;
	struct hlist_node *tmp;
	struct clk *child;

	old_rate = clk->rate;

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

	if (clk->ops->recalc_rate)
		clk->rate = clk->ops->recalc_rate(clk->hw, parent_rate);
	else
		clk->rate = parent_rate;

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

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

/**
 * __clk_speculate_rates
 * @clk: 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 it's parent.
 *
 * Caller must hold prepare_lock.
 */
static int __clk_speculate_rates(struct clk *clk, unsigned long parent_rate)
{
	struct hlist_node *tmp;
	struct clk *child;
	unsigned long new_rate;
	int ret = NOTIFY_DONE;

	if (clk->ops->recalc_rate)
		new_rate = clk->ops->recalc_rate(clk->hw, parent_rate);
	else
		new_rate = parent_rate;

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

	if (ret == NOTIFY_BAD)
		goto out;

	hlist_for_each_entry(child, tmp, &clk->children, child_node) {
		ret = __clk_speculate_rates(child, new_rate);
		if (ret == NOTIFY_BAD)
			break;
	}

out:
	return ret;
}

static void clk_calc_subtree(struct clk *clk, unsigned long new_rate)
{
	struct clk *child;
	struct hlist_node *tmp;

	clk->new_rate = new_rate;

	hlist_for_each_entry(child, tmp, &clk->children, child_node) {
		if (child->ops->recalc_rate)
			child->new_rate = child->ops->recalc_rate(child->hw, new_rate);
		else
			child->new_rate = new_rate;
		clk_calc_subtree(child, child->new_rate);
	}
}

/*
 * calculate the new rates returning the topmost clock that has to be
 * changed.
 */
static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)
{
	struct clk *top = clk;
	unsigned long best_parent_rate = clk->parent->rate;
	unsigned long new_rate;

	if (!clk->ops->round_rate && !(clk->flags & CLK_SET_RATE_PARENT)) {
		clk->new_rate = clk->rate;
		return NULL;
	}

	if (!clk->ops->round_rate && (clk->flags & CLK_SET_RATE_PARENT)) {
		top = clk_calc_new_rates(clk->parent, rate);
		new_rate = clk->new_rate = clk->parent->new_rate;

		goto out;
	}

	if (clk->flags & CLK_SET_RATE_PARENT)
		new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
	else
		new_rate = clk->ops->round_rate(clk->hw, rate, NULL);

	if (best_parent_rate != clk->parent->rate) {
		top = clk_calc_new_rates(clk->parent, best_parent_rate);

		goto out;
	}

out:
	clk_calc_subtree(clk, new_rate);

	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 *clk_propagate_rate_change(struct clk *clk, unsigned long event)
{
	struct hlist_node *tmp;
	struct clk *child, *fail_clk = NULL;
	int ret = NOTIFY_DONE;

	if (clk->rate == clk->new_rate)
		return 0;

	if (clk->notifier_count) {
		ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
		if (ret == NOTIFY_BAD)
			fail_clk = clk;
	}

	hlist_for_each_entry(child, tmp, &clk->children, child_node) {
		clk = clk_propagate_rate_change(child, event);
		if (clk)
			fail_clk = 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 *clk)
{
	struct clk *child;
	unsigned long old_rate;
	struct hlist_node *tmp;

	old_rate = clk->rate;

	if (clk->ops->set_rate)
		clk->ops->set_rate(clk->hw, clk->new_rate);

	if (clk->ops->recalc_rate)
		clk->rate = clk->ops->recalc_rate(clk->hw,
				clk->parent->rate);
	else
		clk->rate = clk->parent->rate;

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

	hlist_for_each_entry(child, tmp, &clk->children, child_node)
		clk_change_rate(child);
}

/**
 * clk_set_rate - specify a new rate for clk
 * @clk: the clk whose rate is being changed
 * @rate: the new rate for clk
 *
860
 * In the simplest case clk_set_rate will only adjust the rate of clk.
861
 *
862 863 864 865 866 867 868 869
 * 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 it's 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.
870
 *
871 872
 * Rate changes are accomplished via tree traversal that also recalculates the
 * rates for the clocks and fires off POST_RATE_CHANGE notifiers.
873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440
 *
 * Returns 0 on success, -EERROR otherwise.
 */
int clk_set_rate(struct clk *clk, unsigned long rate)
{
	struct clk *top, *fail_clk;
	int ret = 0;

	/* prevent racing with updates to the clock topology */
	mutex_lock(&prepare_lock);

	/* bail early if nothing to do */
	if (rate == clk->rate)
		goto out;

	/* calculate new rates and get the topmost changed clock */
	top = clk_calc_new_rates(clk, rate);
	if (!top) {
		ret = -EINVAL;
		goto out;
	}

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

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

	mutex_unlock(&prepare_lock);

	return 0;
out:
	mutex_unlock(&prepare_lock);

	return ret;
}
EXPORT_SYMBOL_GPL(clk_set_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;

	mutex_lock(&prepare_lock);
	parent = __clk_get_parent(clk);
	mutex_unlock(&prepare_lock);

	return parent;
}
EXPORT_SYMBOL_GPL(clk_get_parent);

/*
 * .get_parent is mandatory for clocks with multiple possible parents.  It is
 * optional for single-parent clocks.  Always call .get_parent if it is
 * available and WARN if it is missing for multi-parent clocks.
 *
 * For single-parent clocks without .get_parent, first check to see if the
 * .parents array exists, and if so use it to avoid an expensive tree
 * traversal.  If .parents does not exist then walk the tree with __clk_lookup.
 */
static struct clk *__clk_init_parent(struct clk *clk)
{
	struct clk *ret = NULL;
	u8 index;

	/* handle the trivial cases */

	if (!clk->num_parents)
		goto out;

	if (clk->num_parents == 1) {
		if (IS_ERR_OR_NULL(clk->parent))
			ret = clk->parent = __clk_lookup(clk->parent_names[0]);
		ret = clk->parent;
		goto out;
	}

	if (!clk->ops->get_parent) {
		WARN(!clk->ops->get_parent,
			"%s: multi-parent clocks must implement .get_parent\n",
			__func__);
		goto out;
	};

	/*
	 * Do our best to cache parent clocks in clk->parents.  This prevents
	 * unnecessary and expensive calls to __clk_lookup.  We don't set
	 * clk->parent here; that is done by the calling function
	 */

	index = clk->ops->get_parent(clk->hw);

	if (!clk->parents)
		clk->parents =
			kmalloc((sizeof(struct clk*) * clk->num_parents),
					GFP_KERNEL);

	if (!clk->parents)
		ret = __clk_lookup(clk->parent_names[index]);
	else if (!clk->parents[index])
		ret = clk->parents[index] =
			__clk_lookup(clk->parent_names[index]);
	else
		ret = clk->parents[index];

out:
	return ret;
}

void __clk_reparent(struct clk *clk, struct clk *new_parent)
{
#ifdef CONFIG_COMMON_CLK_DEBUG
	struct dentry *d;
	struct dentry *new_parent_d;
#endif

	if (!clk || !new_parent)
		return;

	hlist_del(&clk->child_node);

	if (new_parent)
		hlist_add_head(&clk->child_node, &new_parent->children);
	else
		hlist_add_head(&clk->child_node, &clk_orphan_list);

#ifdef CONFIG_COMMON_CLK_DEBUG
	if (!inited)
		goto out;

	if (new_parent)
		new_parent_d = new_parent->dentry;
	else
		new_parent_d = orphandir;

	d = debugfs_rename(clk->dentry->d_parent, clk->dentry,
			new_parent_d, clk->name);
	if (d)
		clk->dentry = d;
	else
		pr_debug("%s: failed to rename debugfs entry for %s\n",
				__func__, clk->name);
out:
#endif

	clk->parent = new_parent;

	__clk_recalc_rates(clk, POST_RATE_CHANGE);
}

static int __clk_set_parent(struct clk *clk, struct clk *parent)
{
	struct clk *old_parent;
	unsigned long flags;
	int ret = -EINVAL;
	u8 i;

	old_parent = clk->parent;

	/* find index of new parent clock using cached parent ptrs */
	for (i = 0; i < clk->num_parents; i++)
		if (clk->parents[i] == parent)
			break;

	/*
	 * find index of new parent clock using string name comparison
	 * also try to cache the parent to avoid future calls to __clk_lookup
	 */
	if (i == clk->num_parents)
		for (i = 0; i < clk->num_parents; i++)
			if (!strcmp(clk->parent_names[i], parent->name)) {
				clk->parents[i] = __clk_lookup(parent->name);
				break;
			}

	if (i == clk->num_parents) {
		pr_debug("%s: clock %s is not a possible parent of clock %s\n",
				__func__, parent->name, clk->name);
		goto out;
	}

	/* migrate prepare and enable */
	if (clk->prepare_count)
		__clk_prepare(parent);

	/* FIXME replace with clk_is_enabled(clk) someday */
	spin_lock_irqsave(&enable_lock, flags);
	if (clk->enable_count)
		__clk_enable(parent);
	spin_unlock_irqrestore(&enable_lock, flags);

	/* change clock input source */
	ret = clk->ops->set_parent(clk->hw, i);

	/* clean up old prepare and enable */
	spin_lock_irqsave(&enable_lock, flags);
	if (clk->enable_count)
		__clk_disable(old_parent);
	spin_unlock_irqrestore(&enable_lock, flags);

	if (clk->prepare_count)
		__clk_unprepare(old_parent);

out:
	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 it's new input source.  If clk has the
 * CLK_SET_PARENT_GATE flag set then clk must be gated for this
 * operation to succeed.  After successfully changing clk's parent
 * clk_set_parent will update the clk topology, sysfs topology and
 * propagate rate recalculation via __clk_recalc_rates.  Returns 0 on
 * success, -EERROR otherwise.
 */
int clk_set_parent(struct clk *clk, struct clk *parent)
{
	int ret = 0;

	if (!clk || !clk->ops)
		return -EINVAL;

	if (!clk->ops->set_parent)
		return -ENOSYS;

	/* prevent racing with updates to the clock topology */
	mutex_lock(&prepare_lock);

	if (clk->parent == parent)
		goto out;

	/* propagate PRE_RATE_CHANGE notifications */
	if (clk->notifier_count)
		ret = __clk_speculate_rates(clk, parent->rate);

	/* abort if a driver objects */
	if (ret == NOTIFY_STOP)
		goto out;

	/* only re-parent if the clock is not in use */
	if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count)
		ret = -EBUSY;
	else
		ret = __clk_set_parent(clk, parent);

	/* propagate ABORT_RATE_CHANGE if .set_parent failed */
	if (ret) {
		__clk_recalc_rates(clk, ABORT_RATE_CHANGE);
		goto out;
	}

	/* propagate rate recalculation downstream */
	__clk_reparent(clk, parent);

out:
	mutex_unlock(&prepare_lock);

	return ret;
}
EXPORT_SYMBOL_GPL(clk_set_parent);

/**
 * __clk_init - initialize the data structures in a struct clk
 * @dev:	device initializing this clk, placeholder for now
 * @clk:	clk being initialized
 *
 * Initializes the lists in struct clk, queries the hardware for the
 * parent and rate and sets them both.
 *
 * Any struct clk passed into __clk_init must have the following members
 * populated:
 * 	.name
 * 	.ops
 * 	.hw
 * 	.parent_names
 * 	.num_parents
 * 	.flags
 *
 * Essentially, everything that would normally be passed into clk_register is
 * assumed to be initialized already in __clk_init.  The other members may be
 * populated, but are optional.
 *
 * __clk_init is only exposed via clk-private.h and is intended for use with
 * very large numbers of clocks that need to be statically initialized.  It is
 * a layering violation to include clk-private.h from any code which implements
 * a clock's .ops; as such any statically initialized clock data MUST be in a
 * separate C file from the logic that implements it's operations.
 */
void __clk_init(struct device *dev, struct clk *clk)
{
	int i;
	struct clk *orphan;
	struct hlist_node *tmp, *tmp2;

	if (!clk)
		return;

	mutex_lock(&prepare_lock);

	/* check to see if a clock with this name is already registered */
	if (__clk_lookup(clk->name))
		goto out;

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

	/*
	 * Allocate an array of struct clk *'s to avoid unnecessary string
	 * look-ups of clk's possible parents.  This can fail for clocks passed
	 * in to clk_init during early boot; thus any access to clk->parents[]
	 * must always check for a NULL pointer and try to populate it if
	 * necessary.
	 *
	 * If clk->parents is not NULL we skip this entire block.  This allows
	 * for clock drivers to statically initialize clk->parents.
	 */
	if (clk->num_parents && !clk->parents) {
		clk->parents = kmalloc((sizeof(struct clk*) * clk->num_parents),
				GFP_KERNEL);
		/*
		 * __clk_lookup returns NULL for parents that have not been
		 * clk_init'd; thus any access to clk->parents[] must check
		 * for a NULL pointer.  We can always perform lazy lookups for
		 * missing parents later on.
		 */
		if (clk->parents)
			for (i = 0; i < clk->num_parents; i++)
				clk->parents[i] =
					__clk_lookup(clk->parent_names[i]);
	}

	clk->parent = __clk_init_parent(clk);

	/*
	 * Populate clk->parent if parent has already been __clk_init'd.  If
	 * parent has not yet been __clk_init'd then place clk in the orphan
	 * list.  If clk has set the CLK_IS_ROOT flag 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 (clk->parent)
		hlist_add_head(&clk->child_node,
				&clk->parent->children);
	else if (clk->flags & CLK_IS_ROOT)
		hlist_add_head(&clk->child_node, &clk_root_list);
	else
		hlist_add_head(&clk->child_node, &clk_orphan_list);

	/*
	 * 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 (clk->ops->recalc_rate)
		clk->rate = clk->ops->recalc_rate(clk->hw,
				__clk_get_rate(clk->parent));
	else if (clk->parent)
		clk->rate = clk->parent->rate;
	else
		clk->rate = 0;

	/*
	 * walk the list of orphan clocks and reparent any that are children of
	 * this clock
	 */
	hlist_for_each_entry_safe(orphan, tmp, tmp2, &clk_orphan_list, child_node)
		for (i = 0; i < orphan->num_parents; i++)
			if (!strcmp(clk->name, orphan->parent_names[i])) {
				__clk_reparent(orphan, clk);
				break;
			}

	/*
	 * 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 it's use is discouraged.
	 */
	if (clk->ops->init)
		clk->ops->init(clk->hw);

	clk_debug_register(clk);

out:
	mutex_unlock(&prepare_lock);

	return;
}

/**
 * clk_register - allocate a new clock, register it and return an opaque cookie
 * @dev: device that is registering this clock
 * @name: clock name
 * @ops: operations this clock supports
 * @hw: link to hardware-specific clock data
 * @parent_names: array of string names for all possible parents
 * @num_parents: number of possible parents
 * @flags: framework-level hints and quirks
 *
 * 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 conjuction with the
 * rest of the clock API.
 */
struct clk *clk_register(struct device *dev, const char *name,
		const struct clk_ops *ops, struct clk_hw *hw,
		char **parent_names, u8 num_parents, unsigned long flags)
{
	struct clk *clk;

	clk = kzalloc(sizeof(*clk), GFP_KERNEL);
	if (!clk)
		return NULL;

	clk->name = name;
	clk->ops = ops;
	clk->hw = hw;
	clk->flags = flags;
	clk->parent_names = parent_names;
	clk->num_parents = num_parents;
	hw->clk = clk;

	__clk_init(dev, clk);

	return clk;
}
EXPORT_SYMBOL_GPL(clk_register);

/***        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.
 *
 * Pre-change notifier callbacks will be passed the current, pre-change
 * rate of the clk via struct clk_notifier_data.old_rate.  The new,
 * post-change rate of the clk is passed via struct
 * clk_notifier_data.new_rate.
 *
 * Post-change notifiers will pass the now-current, post-change rate of
 * the clk in both struct clk_notifier_data.old_rate and struct
 * clk_notifier_data.new_rate.
 *
 * Abort-change notifiers are effectively the opposite of pre-change
 * notifiers: the original pre-change clk rate is passed in via struct
 * clk_notifier_data.new_rate and the failed post-change rate is passed
 * in via struct clk_notifier_data.old_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;

	mutex_lock(&prepare_lock);

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

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

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

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

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

	clk->notifier_count++;

out:
	mutex_unlock(&prepare_lock);

	return ret;
}
EXPORT_SYMBOL_GPL(clk_notifier_register);

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

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

	mutex_lock(&prepare_lock);

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

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

		clk->notifier_count--;

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

	} else {
		ret = -ENOENT;
	}

	mutex_unlock(&prepare_lock);

	return ret;
}
EXPORT_SYMBOL_GPL(clk_notifier_unregister);