diff options
Diffstat (limited to 'drivers/clk/clk.c')
| -rw-r--r-- | drivers/clk/clk.c | 1461 |
1 files changed, 1461 insertions, 0 deletions
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c new file mode 100644 index 00000000000..9cf6f59e3e1 --- /dev/null +++ b/drivers/clk/clk.c @@ -0,0 +1,1461 @@ +/* + * 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 /* CONFIG_COMMON_CLK_DEBUG */ + +#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); +#else +static inline int clk_disable_unused(struct clk *clk) { return 0; } +#endif /* CONFIG_COMMON_CLK_DISABLE_UNUSED */ + +/*** 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 + * + * In the simplest case clk_set_rate will only change the rate of clk. + * + * If clk has the CLK_SET_RATE_GATE flag set and it is enabled this call + * will fail; only when the clk is disabled will it be able to change + * its rate. + * + * Setting the CLK_SET_RATE_PARENT flag allows clk_set_rate to + * recursively 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 0 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. If there is a failure during upstream + * propagation then clk_set_rate will unwind and restore each clk's rate + * that had been successfully changed. Afterwards a rate change abort + * notification will be propagated downstream, starting from the clk + * that failed. + * + * At the end of all of the rate setting, clk_set_rate internally calls + * __clk_recalc_rates and propagates the rate changes downstream, + * starting from the highest clk whose rate was changed. This has the + * added benefit of propagating post-rate change notifiers. + * + * Note that while post-rate change and rate change abort notifications + * are guaranteed to be sent to a clk only once per call to + * clk_set_rate, pre-change notifications will be sent for every clk + * whose rate is changed. Stacking pre-change notifications is noisy + * for the drivers subscribed to them, but this allows drivers to react + * to intermediate clk rate changes up until the point where the final + * rate is achieved at the end of upstream propagation. + * + * 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); |