/*
* 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; }
#endif
#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);
#endif
/*** 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 = 0;
goto out;
}
ret = clk->rate;
if (clk->flags & CLK_IS_ROOT)
goto out;
if (!clk->parent)
ret = 0;
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 0.
*/
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 parent_rate = 0;
if (!clk)
return -EINVAL;
if (!clk->ops->round_rate) {
if (clk->flags & CLK_SET_RATE_PARENT)
return __clk_round_rate(clk->parent, rate);
else
return clk->rate;
}
if (clk->parent)
parent_rate = clk->parent->rate;
return clk->ops->round_rate(clk->hw, rate, &parent_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)
{
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 = 0;
unsigned long new_rate;
/* sanity */
if (IS_ERR_OR_NULL(clk))
return NULL;
/* never propagate up to the parent */
if (!(clk->flags & CLK_SET_RATE_PARENT)) {
if (!clk->ops->round_rate) {
clk->new_rate = clk->rate;
return NULL;
}
}
/* need clk->parent from here on out */
if (!clk->parent) {
pr_debug("%s: %s has NULL parent\n", __func__, clk->name);
return NULL;
}
if (!clk->ops->round_rate) {
top = clk_calc_new_rates(clk->parent, rate);
new_rate = clk->parent->new_rate;
goto out;
}
best_parent_rate = clk->parent->rate;
new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
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, clk->parent->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
*
* 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 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.
*
* 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)
{
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. Returns 0
* on success, otherwise an error code.
*/
int __clk_init(struct device *dev, struct clk *clk)
{
int i, ret = 0;
struct clk *orphan;
struct hlist_node *tmp, *tmp2;
if (!clk)
return -EINVAL;
mutex_lock(&prepare_lock);
/* check to see if a clock with this name is already registered */
if (__clk_lookup(clk->name)) {
pr_debug("%s: clk %s already initialized\n",
__func__, clk->name);
ret = -EEXIST;
goto out;
}
/* check that clk_ops are sane. See Documentation/clk.txt */
if (clk->ops->set_rate &&
!(clk->ops->round_rate && clk->ops->recalc_rate)) {
pr_warning("%s: %s must implement .round_rate & .recalc_rate\n",
__func__, clk->name);
ret = -EINVAL;
goto out;
}
if (clk->ops->set_parent && !clk->ops->get_parent) {
pr_warning("%s: %s must implement .get_parent & .set_parent\n",
__func__, clk->name);
ret = -EINVAL;
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 ret;
}
/**
* 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. 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, const char *name,
const struct clk_ops *ops, struct clk_hw *hw,
const char **parent_names, u8 num_parents, unsigned long flags)
{
int i, ret;
struct clk *clk;
clk = kzalloc(sizeof(*clk), GFP_KERNEL);
if (!clk) {
pr_err("%s: could not allocate clk\n", __func__);
ret = -ENOMEM;
goto fail_out;
}
clk->name = name;
clk->ops = ops;
clk->hw = hw;
clk->flags = flags;
clk->num_parents = num_parents;
hw->clk = clk;
/* allocate local copy in case parent_names is __initdata */
clk->parent_names = kzalloc((sizeof(char*) * num_parents),
GFP_KERNEL);
if (!clk->parent_names) {
pr_err("%s: could not allocate clk->parent_names\n", __func__);
ret = -ENOMEM;
goto fail_parent_names;
}
/* copy each string name in case parent_names is __initdata */
for (i = 0; i < num_parents; i++) {
clk->parent_names[i] = kstrdup(parent_names[i], GFP_KERNEL);
if (!clk->parent_names[i]) {
pr_err("%s: could not copy parent_names\n", __func__);
ret = -ENOMEM;
goto fail_parent_names_copy;
}
}
ret = __clk_init(dev, clk);
if (!ret)
return clk;
fail_parent_names_copy:
while (--i >= 0)
kfree(clk->parent_names[i]);
kfree(clk->parent_names);
fail_parent_names:
kfree(clk);
fail_out:
return ERR_PTR(ret);
}
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);
