2 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
3 * Copyright (C) 2011-2012 Linaro Ltd <mturquette@linaro.org>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
9 * Standard functionality for the common clock API. See Documentation/clk.txt
12 #include <linux/clk-private.h>
13 #include <linux/module.h>
14 #include <linux/mutex.h>
15 #include <linux/spinlock.h>
16 #include <linux/err.h>
17 #include <linux/list.h>
18 #include <linux/slab.h>
20 static DEFINE_SPINLOCK(enable_lock);
21 static DEFINE_MUTEX(prepare_lock);
23 static HLIST_HEAD(clk_root_list);
24 static HLIST_HEAD(clk_orphan_list);
25 static LIST_HEAD(clk_notifier_list);
27 /*** debugfs support ***/
29 #ifdef CONFIG_COMMON_CLK_DEBUG
30 #include <linux/debugfs.h>
32 static struct dentry *rootdir;
33 static struct dentry *orphandir;
34 static int inited = 0;
36 /* caller must hold prepare_lock */
37 static int clk_debug_create_one(struct clk *clk, struct dentry *pdentry)
42 if (!clk || !pdentry) {
47 d = debugfs_create_dir(clk->name, pdentry);
53 d = debugfs_create_u32("clk_rate", S_IRUGO, clk->dentry,
58 d = debugfs_create_x32("clk_flags", S_IRUGO, clk->dentry,
63 d = debugfs_create_u32("clk_prepare_count", S_IRUGO, clk->dentry,
64 (u32 *)&clk->prepare_count);
68 d = debugfs_create_u32("clk_enable_count", S_IRUGO, clk->dentry,
69 (u32 *)&clk->enable_count);
73 d = debugfs_create_u32("clk_notifier_count", S_IRUGO, clk->dentry,
74 (u32 *)&clk->notifier_count);
82 debugfs_remove(clk->dentry);
87 /* caller must hold prepare_lock */
88 static int clk_debug_create_subtree(struct clk *clk, struct dentry *pdentry)
91 struct hlist_node *tmp;
97 ret = clk_debug_create_one(clk, pdentry);
102 hlist_for_each_entry(child, tmp, &clk->children, child_node)
103 clk_debug_create_subtree(child, clk->dentry);
111 * clk_debug_register - add a clk node to the debugfs clk tree
112 * @clk: the clk being added to the debugfs clk tree
114 * Dynamically adds a clk to the debugfs clk tree if debugfs has been
115 * initialized. Otherwise it bails out early since the debugfs clk tree
116 * will be created lazily by clk_debug_init as part of a late_initcall.
118 * Caller must hold prepare_lock. Only clk_init calls this function (so
119 * far) so this is taken care.
121 static int clk_debug_register(struct clk *clk)
124 struct dentry *pdentry;
130 parent = clk->parent;
133 * Check to see if a clk is a root clk. Also check that it is
134 * safe to add this clk to debugfs
137 if (clk->flags & CLK_IS_ROOT)
143 pdentry = parent->dentry;
147 ret = clk_debug_create_subtree(clk, pdentry);
154 * clk_debug_init - lazily create the debugfs clk tree visualization
156 * clks are often initialized very early during boot before memory can
157 * be dynamically allocated and well before debugfs is setup.
158 * clk_debug_init walks the clk tree hierarchy while holding
159 * prepare_lock and creates the topology as part of a late_initcall,
160 * thus insuring that clks initialized very early will still be
161 * represented in the debugfs clk tree. This function should only be
162 * called once at boot-time, and all other clks added dynamically will
163 * be done so with clk_debug_register.
165 static int __init clk_debug_init(void)
168 struct hlist_node *tmp;
170 rootdir = debugfs_create_dir("clk", NULL);
175 orphandir = debugfs_create_dir("orphans", rootdir);
180 mutex_lock(&prepare_lock);
182 hlist_for_each_entry(clk, tmp, &clk_root_list, child_node)
183 clk_debug_create_subtree(clk, rootdir);
185 hlist_for_each_entry(clk, tmp, &clk_orphan_list, child_node)
186 clk_debug_create_subtree(clk, orphandir);
190 mutex_unlock(&prepare_lock);
194 late_initcall(clk_debug_init);
196 static inline int clk_debug_register(struct clk *clk) { return 0; }
199 #ifdef CONFIG_COMMON_CLK_DISABLE_UNUSED
200 /* caller must hold prepare_lock */
201 static void clk_disable_unused_subtree(struct clk *clk)
204 struct hlist_node *tmp;
210 hlist_for_each_entry(child, tmp, &clk->children, child_node)
211 clk_disable_unused_subtree(child);
213 spin_lock_irqsave(&enable_lock, flags);
215 if (clk->enable_count)
218 if (clk->flags & CLK_IGNORE_UNUSED)
221 if (__clk_is_enabled(clk) && clk->ops->disable)
222 clk->ops->disable(clk->hw);
225 spin_unlock_irqrestore(&enable_lock, flags);
231 static int clk_disable_unused(void)
234 struct hlist_node *tmp;
236 mutex_lock(&prepare_lock);
238 hlist_for_each_entry(clk, tmp, &clk_root_list, child_node)
239 clk_disable_unused_subtree(clk);
241 hlist_for_each_entry(clk, tmp, &clk_orphan_list, child_node)
242 clk_disable_unused_subtree(clk);
244 mutex_unlock(&prepare_lock);
248 late_initcall(clk_disable_unused);
251 /*** helper functions ***/
253 inline const char *__clk_get_name(struct clk *clk)
255 return !clk ? NULL : clk->name;
258 inline struct clk_hw *__clk_get_hw(struct clk *clk)
260 return !clk ? NULL : clk->hw;
263 inline u8 __clk_get_num_parents(struct clk *clk)
265 return !clk ? -EINVAL : clk->num_parents;
268 inline struct clk *__clk_get_parent(struct clk *clk)
270 return !clk ? NULL : clk->parent;
273 inline int __clk_get_enable_count(struct clk *clk)
275 return !clk ? -EINVAL : clk->enable_count;
278 inline int __clk_get_prepare_count(struct clk *clk)
280 return !clk ? -EINVAL : clk->prepare_count;
283 unsigned long __clk_get_rate(struct clk *clk)
294 if (clk->flags & CLK_IS_ROOT)
304 inline unsigned long __clk_get_flags(struct clk *clk)
306 return !clk ? -EINVAL : clk->flags;
309 int __clk_is_enabled(struct clk *clk)
317 * .is_enabled is only mandatory for clocks that gate
318 * fall back to software usage counter if .is_enabled is missing
320 if (!clk->ops->is_enabled) {
321 ret = clk->enable_count ? 1 : 0;
325 ret = clk->ops->is_enabled(clk->hw);
330 static struct clk *__clk_lookup_subtree(const char *name, struct clk *clk)
334 struct hlist_node *tmp;
336 if (!strcmp(clk->name, name))
339 hlist_for_each_entry(child, tmp, &clk->children, child_node) {
340 ret = __clk_lookup_subtree(name, child);
348 struct clk *__clk_lookup(const char *name)
350 struct clk *root_clk;
352 struct hlist_node *tmp;
357 /* search the 'proper' clk tree first */
358 hlist_for_each_entry(root_clk, tmp, &clk_root_list, child_node) {
359 ret = __clk_lookup_subtree(name, root_clk);
364 /* if not found, then search the orphan tree */
365 hlist_for_each_entry(root_clk, tmp, &clk_orphan_list, child_node) {
366 ret = __clk_lookup_subtree(name, root_clk);
376 void __clk_unprepare(struct clk *clk)
381 if (WARN_ON(clk->prepare_count == 0))
384 if (--clk->prepare_count > 0)
387 WARN_ON(clk->enable_count > 0);
389 if (clk->ops->unprepare)
390 clk->ops->unprepare(clk->hw);
392 __clk_unprepare(clk->parent);
396 * clk_unprepare - undo preparation of a clock source
397 * @clk: the clk being unprepare
399 * clk_unprepare may sleep, which differentiates it from clk_disable. In a
400 * simple case, clk_unprepare can be used instead of clk_disable to gate a clk
401 * if the operation may sleep. One example is a clk which is accessed over
402 * I2c. In the complex case a clk gate operation may require a fast and a slow
403 * part. It is this reason that clk_unprepare and clk_disable are not mutually
404 * exclusive. In fact clk_disable must be called before clk_unprepare.
406 void clk_unprepare(struct clk *clk)
408 mutex_lock(&prepare_lock);
409 __clk_unprepare(clk);
410 mutex_unlock(&prepare_lock);
412 EXPORT_SYMBOL_GPL(clk_unprepare);
414 int __clk_prepare(struct clk *clk)
421 if (clk->prepare_count == 0) {
422 ret = __clk_prepare(clk->parent);
426 if (clk->ops->prepare) {
427 ret = clk->ops->prepare(clk->hw);
429 __clk_unprepare(clk->parent);
435 clk->prepare_count++;
441 * clk_prepare - prepare a clock source
442 * @clk: the clk being prepared
444 * clk_prepare may sleep, which differentiates it from clk_enable. In a simple
445 * case, clk_prepare can be used instead of clk_enable to ungate a clk if the
446 * operation may sleep. One example is a clk which is accessed over I2c. In
447 * the complex case a clk ungate operation may require a fast and a slow part.
448 * It is this reason that clk_prepare and clk_enable are not mutually
449 * exclusive. In fact clk_prepare must be called before clk_enable.
450 * Returns 0 on success, -EERROR otherwise.
452 int clk_prepare(struct clk *clk)
456 mutex_lock(&prepare_lock);
457 ret = __clk_prepare(clk);
458 mutex_unlock(&prepare_lock);
462 EXPORT_SYMBOL_GPL(clk_prepare);
464 static void __clk_disable(struct clk *clk)
469 if (WARN_ON(clk->enable_count == 0))
472 if (--clk->enable_count > 0)
475 if (clk->ops->disable)
476 clk->ops->disable(clk->hw);
478 __clk_disable(clk->parent);
482 * clk_disable - gate a clock
483 * @clk: the clk being gated
485 * clk_disable must not sleep, which differentiates it from clk_unprepare. In
486 * a simple case, clk_disable can be used instead of clk_unprepare to gate a
487 * clk if the operation is fast and will never sleep. One example is a
488 * SoC-internal clk which is controlled via simple register writes. In the
489 * complex case a clk gate operation may require a fast and a slow part. It is
490 * this reason that clk_unprepare and clk_disable are not mutually exclusive.
491 * In fact clk_disable must be called before clk_unprepare.
493 void clk_disable(struct clk *clk)
497 spin_lock_irqsave(&enable_lock, flags);
499 spin_unlock_irqrestore(&enable_lock, flags);
501 EXPORT_SYMBOL_GPL(clk_disable);
503 static int __clk_enable(struct clk *clk)
510 if (WARN_ON(clk->prepare_count == 0))
513 if (clk->enable_count == 0) {
514 ret = __clk_enable(clk->parent);
519 if (clk->ops->enable) {
520 ret = clk->ops->enable(clk->hw);
522 __clk_disable(clk->parent);
533 * clk_enable - ungate a clock
534 * @clk: the clk being ungated
536 * clk_enable must not sleep, which differentiates it from clk_prepare. In a
537 * simple case, clk_enable can be used instead of clk_prepare to ungate a clk
538 * if the operation will never sleep. One example is a SoC-internal clk which
539 * is controlled via simple register writes. In the complex case a clk ungate
540 * operation may require a fast and a slow part. It is this reason that
541 * clk_enable and clk_prepare are not mutually exclusive. In fact clk_prepare
542 * must be called before clk_enable. Returns 0 on success, -EERROR
545 int clk_enable(struct clk *clk)
550 spin_lock_irqsave(&enable_lock, flags);
551 ret = __clk_enable(clk);
552 spin_unlock_irqrestore(&enable_lock, flags);
556 EXPORT_SYMBOL_GPL(clk_enable);
559 * clk_get_rate - return the rate of clk
560 * @clk: the clk whose rate is being returned
562 * Simply returns the cached rate of the clk. Does not query the hardware. If
563 * clk is NULL then returns 0.
565 unsigned long clk_get_rate(struct clk *clk)
569 mutex_lock(&prepare_lock);
570 rate = __clk_get_rate(clk);
571 mutex_unlock(&prepare_lock);
575 EXPORT_SYMBOL_GPL(clk_get_rate);
578 * __clk_round_rate - round the given rate for a clk
579 * @clk: round the rate of this clock
581 * Caller must hold prepare_lock. Useful for clk_ops such as .set_rate
583 unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
585 unsigned long unused;
590 if (!clk->ops->round_rate)
593 if (clk->flags & CLK_SET_RATE_PARENT)
594 return clk->ops->round_rate(clk->hw, rate, &unused);
596 return clk->ops->round_rate(clk->hw, rate, NULL);
600 * clk_round_rate - round the given rate for a clk
601 * @clk: the clk for which we are rounding a rate
602 * @rate: the rate which is to be rounded
604 * Takes in a rate as input and rounds it to a rate that the clk can actually
605 * use which is then returned. If clk doesn't support round_rate operation
606 * then the parent rate is returned.
608 long clk_round_rate(struct clk *clk, unsigned long rate)
612 mutex_lock(&prepare_lock);
613 ret = __clk_round_rate(clk, rate);
614 mutex_unlock(&prepare_lock);
618 EXPORT_SYMBOL_GPL(clk_round_rate);
621 * __clk_notify - call clk notifier chain
622 * @clk: struct clk * that is changing rate
623 * @msg: clk notifier type (see include/linux/clk.h)
624 * @old_rate: old clk rate
625 * @new_rate: new clk rate
627 * Triggers a notifier call chain on the clk rate-change notification
628 * for 'clk'. Passes a pointer to the struct clk and the previous
629 * and current rates to the notifier callback. Intended to be called by
630 * internal clock code only. Returns NOTIFY_DONE from the last driver
631 * called if all went well, or NOTIFY_STOP or NOTIFY_BAD immediately if
632 * a driver returns that.
634 static int __clk_notify(struct clk *clk, unsigned long msg,
635 unsigned long old_rate, unsigned long new_rate)
637 struct clk_notifier *cn;
638 struct clk_notifier_data cnd;
639 int ret = NOTIFY_DONE;
642 cnd.old_rate = old_rate;
643 cnd.new_rate = new_rate;
645 list_for_each_entry(cn, &clk_notifier_list, node) {
646 if (cn->clk == clk) {
647 ret = srcu_notifier_call_chain(&cn->notifier_head, msg,
658 * @clk: first clk in the subtree
659 * @msg: notification type (see include/linux/clk.h)
661 * Walks the subtree of clks starting with clk and recalculates rates as it
662 * goes. Note that if a clk does not implement the .recalc_rate callback then
663 * it is assumed that the clock will take on the rate of it's parent.
665 * clk_recalc_rates also propagates the POST_RATE_CHANGE notification,
668 * Caller must hold prepare_lock.
670 static void __clk_recalc_rates(struct clk *clk, unsigned long msg)
672 unsigned long old_rate;
673 unsigned long parent_rate = 0;
674 struct hlist_node *tmp;
677 old_rate = clk->rate;
680 parent_rate = clk->parent->rate;
682 if (clk->ops->recalc_rate)
683 clk->rate = clk->ops->recalc_rate(clk->hw, parent_rate);
685 clk->rate = parent_rate;
688 * ignore NOTIFY_STOP and NOTIFY_BAD return values for POST_RATE_CHANGE
689 * & ABORT_RATE_CHANGE notifiers
691 if (clk->notifier_count && msg)
692 __clk_notify(clk, msg, old_rate, clk->rate);
694 hlist_for_each_entry(child, tmp, &clk->children, child_node)
695 __clk_recalc_rates(child, msg);
699 * __clk_speculate_rates
700 * @clk: first clk in the subtree
701 * @parent_rate: the "future" rate of clk's parent
703 * Walks the subtree of clks starting with clk, speculating rates as it
704 * goes and firing off PRE_RATE_CHANGE notifications as necessary.
706 * Unlike clk_recalc_rates, clk_speculate_rates exists only for sending
707 * pre-rate change notifications and returns early if no clks in the
708 * subtree have subscribed to the notifications. Note that if a clk does not
709 * implement the .recalc_rate callback then it is assumed that the clock will
710 * take on the rate of it's parent.
712 * Caller must hold prepare_lock.
714 static int __clk_speculate_rates(struct clk *clk, unsigned long parent_rate)
716 struct hlist_node *tmp;
718 unsigned long new_rate;
719 int ret = NOTIFY_DONE;
721 if (clk->ops->recalc_rate)
722 new_rate = clk->ops->recalc_rate(clk->hw, parent_rate);
724 new_rate = parent_rate;
726 /* abort the rate change if a driver returns NOTIFY_BAD */
727 if (clk->notifier_count)
728 ret = __clk_notify(clk, PRE_RATE_CHANGE, clk->rate, new_rate);
730 if (ret == NOTIFY_BAD)
733 hlist_for_each_entry(child, tmp, &clk->children, child_node) {
734 ret = __clk_speculate_rates(child, new_rate);
735 if (ret == NOTIFY_BAD)
743 static void clk_calc_subtree(struct clk *clk, unsigned long new_rate)
746 struct hlist_node *tmp;
748 clk->new_rate = new_rate;
750 hlist_for_each_entry(child, tmp, &clk->children, child_node) {
751 if (child->ops->recalc_rate)
752 child->new_rate = child->ops->recalc_rate(child->hw, new_rate);
754 child->new_rate = new_rate;
755 clk_calc_subtree(child, child->new_rate);
760 * calculate the new rates returning the topmost clock that has to be
763 static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)
765 struct clk *top = clk;
766 unsigned long best_parent_rate;
767 unsigned long new_rate;
770 if (IS_ERR_OR_NULL(clk))
773 /* never propagate up to the parent */
774 if (!(clk->flags & CLK_SET_RATE_PARENT)) {
775 if (!clk->ops->round_rate) {
776 clk->new_rate = clk->rate;
779 new_rate = clk->ops->round_rate(clk->hw, rate, NULL);
784 /* need clk->parent from here on out */
786 pr_debug("%s: %s has NULL parent\n", __func__, clk->name);
790 if (!clk->ops->round_rate) {
791 top = clk_calc_new_rates(clk->parent, rate);
792 new_rate = clk->new_rate = clk->parent->new_rate;
797 new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
799 if (best_parent_rate != clk->parent->rate) {
800 top = clk_calc_new_rates(clk->parent, best_parent_rate);
806 clk_calc_subtree(clk, new_rate);
812 * Notify about rate changes in a subtree. Always walk down the whole tree
813 * so that in case of an error we can walk down the whole tree again and
816 static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long event)
818 struct hlist_node *tmp;
819 struct clk *child, *fail_clk = NULL;
820 int ret = NOTIFY_DONE;
822 if (clk->rate == clk->new_rate)
825 if (clk->notifier_count) {
826 ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
827 if (ret == NOTIFY_BAD)
831 hlist_for_each_entry(child, tmp, &clk->children, child_node) {
832 clk = clk_propagate_rate_change(child, event);
841 * walk down a subtree and set the new rates notifying the rate
844 static void clk_change_rate(struct clk *clk)
847 unsigned long old_rate;
848 struct hlist_node *tmp;
850 old_rate = clk->rate;
852 if (clk->ops->set_rate)
853 clk->ops->set_rate(clk->hw, clk->new_rate);
855 if (clk->ops->recalc_rate)
856 clk->rate = clk->ops->recalc_rate(clk->hw,
859 clk->rate = clk->parent->rate;
861 if (clk->notifier_count && old_rate != clk->rate)
862 __clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate);
864 hlist_for_each_entry(child, tmp, &clk->children, child_node)
865 clk_change_rate(child);
869 * clk_set_rate - specify a new rate for clk
870 * @clk: the clk whose rate is being changed
871 * @rate: the new rate for clk
873 * In the simplest case clk_set_rate will only adjust the rate of clk.
875 * Setting the CLK_SET_RATE_PARENT flag allows the rate change operation to
876 * propagate up to clk's parent; whether or not this happens depends on the
877 * outcome of clk's .round_rate implementation. If *parent_rate is unchanged
878 * after calling .round_rate then upstream parent propagation is ignored. If
879 * *parent_rate comes back with a new rate for clk's parent then we propagate
880 * up to clk's parent and set it's rate. Upward propagation will continue
881 * until either a clk does not support the CLK_SET_RATE_PARENT flag or
882 * .round_rate stops requesting changes to clk's parent_rate.
884 * Rate changes are accomplished via tree traversal that also recalculates the
885 * rates for the clocks and fires off POST_RATE_CHANGE notifiers.
887 * Returns 0 on success, -EERROR otherwise.
889 int clk_set_rate(struct clk *clk, unsigned long rate)
891 struct clk *top, *fail_clk;
894 /* prevent racing with updates to the clock topology */
895 mutex_lock(&prepare_lock);
897 /* bail early if nothing to do */
898 if (rate == clk->rate)
901 /* calculate new rates and get the topmost changed clock */
902 top = clk_calc_new_rates(clk, rate);
908 /* notify that we are about to change rates */
909 fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE);
911 pr_warn("%s: failed to set %s rate\n", __func__,
913 clk_propagate_rate_change(top, ABORT_RATE_CHANGE);
918 /* change the rates */
919 clk_change_rate(top);
921 mutex_unlock(&prepare_lock);
925 mutex_unlock(&prepare_lock);
929 EXPORT_SYMBOL_GPL(clk_set_rate);
932 * clk_get_parent - return the parent of a clk
933 * @clk: the clk whose parent gets returned
935 * Simply returns clk->parent. Returns NULL if clk is NULL.
937 struct clk *clk_get_parent(struct clk *clk)
941 mutex_lock(&prepare_lock);
942 parent = __clk_get_parent(clk);
943 mutex_unlock(&prepare_lock);
947 EXPORT_SYMBOL_GPL(clk_get_parent);
950 * .get_parent is mandatory for clocks with multiple possible parents. It is
951 * optional for single-parent clocks. Always call .get_parent if it is
952 * available and WARN if it is missing for multi-parent clocks.
954 * For single-parent clocks without .get_parent, first check to see if the
955 * .parents array exists, and if so use it to avoid an expensive tree
956 * traversal. If .parents does not exist then walk the tree with __clk_lookup.
958 static struct clk *__clk_init_parent(struct clk *clk)
960 struct clk *ret = NULL;
963 /* handle the trivial cases */
965 if (!clk->num_parents)
968 if (clk->num_parents == 1) {
969 if (IS_ERR_OR_NULL(clk->parent))
970 ret = clk->parent = __clk_lookup(clk->parent_names[0]);
975 if (!clk->ops->get_parent) {
976 WARN(!clk->ops->get_parent,
977 "%s: multi-parent clocks must implement .get_parent\n",
983 * Do our best to cache parent clocks in clk->parents. This prevents
984 * unnecessary and expensive calls to __clk_lookup. We don't set
985 * clk->parent here; that is done by the calling function
988 index = clk->ops->get_parent(clk->hw);
992 kmalloc((sizeof(struct clk*) * clk->num_parents),
996 ret = __clk_lookup(clk->parent_names[index]);
997 else if (!clk->parents[index])
998 ret = clk->parents[index] =
999 __clk_lookup(clk->parent_names[index]);
1001 ret = clk->parents[index];
1007 void __clk_reparent(struct clk *clk, struct clk *new_parent)
1009 #ifdef CONFIG_COMMON_CLK_DEBUG
1011 struct dentry *new_parent_d;
1014 if (!clk || !new_parent)
1017 hlist_del(&clk->child_node);
1020 hlist_add_head(&clk->child_node, &new_parent->children);
1022 hlist_add_head(&clk->child_node, &clk_orphan_list);
1024 #ifdef CONFIG_COMMON_CLK_DEBUG
1029 new_parent_d = new_parent->dentry;
1031 new_parent_d = orphandir;
1033 d = debugfs_rename(clk->dentry->d_parent, clk->dentry,
1034 new_parent_d, clk->name);
1038 pr_debug("%s: failed to rename debugfs entry for %s\n",
1039 __func__, clk->name);
1043 clk->parent = new_parent;
1045 __clk_recalc_rates(clk, POST_RATE_CHANGE);
1048 static int __clk_set_parent(struct clk *clk, struct clk *parent)
1050 struct clk *old_parent;
1051 unsigned long flags;
1055 old_parent = clk->parent;
1057 /* find index of new parent clock using cached parent ptrs */
1058 for (i = 0; i < clk->num_parents; i++)
1059 if (clk->parents[i] == parent)
1063 * find index of new parent clock using string name comparison
1064 * also try to cache the parent to avoid future calls to __clk_lookup
1066 if (i == clk->num_parents)
1067 for (i = 0; i < clk->num_parents; i++)
1068 if (!strcmp(clk->parent_names[i], parent->name)) {
1069 clk->parents[i] = __clk_lookup(parent->name);
1073 if (i == clk->num_parents) {
1074 pr_debug("%s: clock %s is not a possible parent of clock %s\n",
1075 __func__, parent->name, clk->name);
1079 /* migrate prepare and enable */
1080 if (clk->prepare_count)
1081 __clk_prepare(parent);
1083 /* FIXME replace with clk_is_enabled(clk) someday */
1084 spin_lock_irqsave(&enable_lock, flags);
1085 if (clk->enable_count)
1086 __clk_enable(parent);
1087 spin_unlock_irqrestore(&enable_lock, flags);
1089 /* change clock input source */
1090 ret = clk->ops->set_parent(clk->hw, i);
1092 /* clean up old prepare and enable */
1093 spin_lock_irqsave(&enable_lock, flags);
1094 if (clk->enable_count)
1095 __clk_disable(old_parent);
1096 spin_unlock_irqrestore(&enable_lock, flags);
1098 if (clk->prepare_count)
1099 __clk_unprepare(old_parent);
1106 * clk_set_parent - switch the parent of a mux clk
1107 * @clk: the mux clk whose input we are switching
1108 * @parent: the new input to clk
1110 * Re-parent clk to use parent as it's new input source. If clk has the
1111 * CLK_SET_PARENT_GATE flag set then clk must be gated for this
1112 * operation to succeed. After successfully changing clk's parent
1113 * clk_set_parent will update the clk topology, sysfs topology and
1114 * propagate rate recalculation via __clk_recalc_rates. Returns 0 on
1115 * success, -EERROR otherwise.
1117 int clk_set_parent(struct clk *clk, struct clk *parent)
1121 if (!clk || !clk->ops)
1124 if (!clk->ops->set_parent)
1127 /* prevent racing with updates to the clock topology */
1128 mutex_lock(&prepare_lock);
1130 if (clk->parent == parent)
1133 /* propagate PRE_RATE_CHANGE notifications */
1134 if (clk->notifier_count)
1135 ret = __clk_speculate_rates(clk, parent->rate);
1137 /* abort if a driver objects */
1138 if (ret == NOTIFY_STOP)
1141 /* only re-parent if the clock is not in use */
1142 if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count)
1145 ret = __clk_set_parent(clk, parent);
1147 /* propagate ABORT_RATE_CHANGE if .set_parent failed */
1149 __clk_recalc_rates(clk, ABORT_RATE_CHANGE);
1153 /* propagate rate recalculation downstream */
1154 __clk_reparent(clk, parent);
1157 mutex_unlock(&prepare_lock);
1161 EXPORT_SYMBOL_GPL(clk_set_parent);
1164 * __clk_init - initialize the data structures in a struct clk
1165 * @dev: device initializing this clk, placeholder for now
1166 * @clk: clk being initialized
1168 * Initializes the lists in struct clk, queries the hardware for the
1169 * parent and rate and sets them both.
1171 * Any struct clk passed into __clk_init must have the following members
1180 * Essentially, everything that would normally be passed into clk_register is
1181 * assumed to be initialized already in __clk_init. The other members may be
1182 * populated, but are optional.
1184 * __clk_init is only exposed via clk-private.h and is intended for use with
1185 * very large numbers of clocks that need to be statically initialized. It is
1186 * a layering violation to include clk-private.h from any code which implements
1187 * a clock's .ops; as such any statically initialized clock data MUST be in a
1188 * separate C file from the logic that implements it's operations. Returns 0
1189 * on success, otherwise an error code.
1191 int __clk_init(struct device *dev, struct clk *clk)
1195 struct hlist_node *tmp, *tmp2;
1200 mutex_lock(&prepare_lock);
1202 /* check to see if a clock with this name is already registered */
1203 if (__clk_lookup(clk->name)) {
1204 pr_debug("%s: clk %s already initialized\n",
1205 __func__, clk->name);
1210 /* check that clk_ops are sane. See Documentation/clk.txt */
1211 if (clk->ops->set_rate &&
1212 !(clk->ops->round_rate && clk->ops->recalc_rate)) {
1213 pr_warning("%s: %s must implement .round_rate & .recalc_rate\n",
1214 __func__, clk->name);
1219 if (clk->ops->set_parent && !clk->ops->get_parent) {
1220 pr_warning("%s: %s must implement .get_parent & .set_parent\n",
1221 __func__, clk->name);
1226 /* throw a WARN if any entries in parent_names are NULL */
1227 for (i = 0; i < clk->num_parents; i++)
1228 WARN(!clk->parent_names[i],
1229 "%s: invalid NULL in %s's .parent_names\n",
1230 __func__, clk->name);
1233 * Allocate an array of struct clk *'s to avoid unnecessary string
1234 * look-ups of clk's possible parents. This can fail for clocks passed
1235 * in to clk_init during early boot; thus any access to clk->parents[]
1236 * must always check for a NULL pointer and try to populate it if
1239 * If clk->parents is not NULL we skip this entire block. This allows
1240 * for clock drivers to statically initialize clk->parents.
1242 if (clk->num_parents && !clk->parents) {
1243 clk->parents = kmalloc((sizeof(struct clk*) * clk->num_parents),
1246 * __clk_lookup returns NULL for parents that have not been
1247 * clk_init'd; thus any access to clk->parents[] must check
1248 * for a NULL pointer. We can always perform lazy lookups for
1249 * missing parents later on.
1252 for (i = 0; i < clk->num_parents; i++)
1254 __clk_lookup(clk->parent_names[i]);
1257 clk->parent = __clk_init_parent(clk);
1260 * Populate clk->parent if parent has already been __clk_init'd. If
1261 * parent has not yet been __clk_init'd then place clk in the orphan
1262 * list. If clk has set the CLK_IS_ROOT flag then place it in the root
1265 * Every time a new clk is clk_init'd then we walk the list of orphan
1266 * clocks and re-parent any that are children of the clock currently
1270 hlist_add_head(&clk->child_node,
1271 &clk->parent->children);
1272 else if (clk->flags & CLK_IS_ROOT)
1273 hlist_add_head(&clk->child_node, &clk_root_list);
1275 hlist_add_head(&clk->child_node, &clk_orphan_list);
1278 * Set clk's rate. The preferred method is to use .recalc_rate. For
1279 * simple clocks and lazy developers the default fallback is to use the
1280 * parent's rate. If a clock doesn't have a parent (or is orphaned)
1281 * then rate is set to zero.
1283 if (clk->ops->recalc_rate)
1284 clk->rate = clk->ops->recalc_rate(clk->hw,
1285 __clk_get_rate(clk->parent));
1286 else if (clk->parent)
1287 clk->rate = clk->parent->rate;
1292 * walk the list of orphan clocks and reparent any that are children of
1295 hlist_for_each_entry_safe(orphan, tmp, tmp2, &clk_orphan_list, child_node)
1296 for (i = 0; i < orphan->num_parents; i++)
1297 if (!strcmp(clk->name, orphan->parent_names[i])) {
1298 __clk_reparent(orphan, clk);
1303 * optional platform-specific magic
1305 * The .init callback is not used by any of the basic clock types, but
1306 * exists for weird hardware that must perform initialization magic.
1307 * Please consider other ways of solving initialization problems before
1308 * using this callback, as it's use is discouraged.
1311 clk->ops->init(clk->hw);
1313 clk_debug_register(clk);
1316 mutex_unlock(&prepare_lock);
1322 * clk_register - allocate a new clock, register it and return an opaque cookie
1323 * @dev: device that is registering this clock
1325 * @ops: operations this clock supports
1326 * @hw: link to hardware-specific clock data
1327 * @parent_names: array of string names for all possible parents
1328 * @num_parents: number of possible parents
1329 * @flags: framework-level hints and quirks
1331 * clk_register is the primary interface for populating the clock tree with new
1332 * clock nodes. It returns a pointer to the newly allocated struct clk which
1333 * cannot be dereferenced by driver code but may be used in conjuction with the
1334 * rest of the clock API. In the event of an error clk_register will return an
1335 * error code; drivers must test for an error code after calling clk_register.
1337 struct clk *clk_register(struct device *dev, const char *name,
1338 const struct clk_ops *ops, struct clk_hw *hw,
1339 const char **parent_names, u8 num_parents, unsigned long flags)
1344 clk = kzalloc(sizeof(*clk), GFP_KERNEL);
1346 pr_err("%s: could not allocate clk\n", __func__);
1355 clk->num_parents = num_parents;
1358 /* allocate local copy in case parent_names is __initdata */
1359 clk->parent_names = kzalloc((sizeof(char*) * num_parents),
1362 if (!clk->parent_names) {
1363 pr_err("%s: could not allocate clk->parent_names\n", __func__);
1365 goto fail_parent_names;
1369 /* copy each string name in case parent_names is __initdata */
1370 for (i = 0; i < num_parents; i++) {
1371 clk->parent_names[i] = kstrdup(parent_names[i], GFP_KERNEL);
1372 if (!clk->parent_names[i]) {
1373 pr_err("%s: could not copy parent_names\n", __func__);
1375 goto fail_parent_names_copy;
1379 ret = __clk_init(dev, clk);
1383 fail_parent_names_copy:
1385 kfree(clk->parent_names[i]);
1386 kfree(clk->parent_names);
1390 return ERR_PTR(ret);
1392 EXPORT_SYMBOL_GPL(clk_register);
1394 /*** clk rate change notifiers ***/
1397 * clk_notifier_register - add a clk rate change notifier
1398 * @clk: struct clk * to watch
1399 * @nb: struct notifier_block * with callback info
1401 * Request notification when clk's rate changes. This uses an SRCU
1402 * notifier because we want it to block and notifier unregistrations are
1403 * uncommon. The callbacks associated with the notifier must not
1404 * re-enter into the clk framework by calling any top-level clk APIs;
1405 * this will cause a nested prepare_lock mutex.
1407 * Pre-change notifier callbacks will be passed the current, pre-change
1408 * rate of the clk via struct clk_notifier_data.old_rate. The new,
1409 * post-change rate of the clk is passed via struct
1410 * clk_notifier_data.new_rate.
1412 * Post-change notifiers will pass the now-current, post-change rate of
1413 * the clk in both struct clk_notifier_data.old_rate and struct
1414 * clk_notifier_data.new_rate.
1416 * Abort-change notifiers are effectively the opposite of pre-change
1417 * notifiers: the original pre-change clk rate is passed in via struct
1418 * clk_notifier_data.new_rate and the failed post-change rate is passed
1419 * in via struct clk_notifier_data.old_rate.
1421 * clk_notifier_register() must be called from non-atomic context.
1422 * Returns -EINVAL if called with null arguments, -ENOMEM upon
1423 * allocation failure; otherwise, passes along the return value of
1424 * srcu_notifier_chain_register().
1426 int clk_notifier_register(struct clk *clk, struct notifier_block *nb)
1428 struct clk_notifier *cn;
1434 mutex_lock(&prepare_lock);
1436 /* search the list of notifiers for this clk */
1437 list_for_each_entry(cn, &clk_notifier_list, node)
1441 /* if clk wasn't in the notifier list, allocate new clk_notifier */
1442 if (cn->clk != clk) {
1443 cn = kzalloc(sizeof(struct clk_notifier), GFP_KERNEL);
1448 srcu_init_notifier_head(&cn->notifier_head);
1450 list_add(&cn->node, &clk_notifier_list);
1453 ret = srcu_notifier_chain_register(&cn->notifier_head, nb);
1455 clk->notifier_count++;
1458 mutex_unlock(&prepare_lock);
1462 EXPORT_SYMBOL_GPL(clk_notifier_register);
1465 * clk_notifier_unregister - remove a clk rate change notifier
1466 * @clk: struct clk *
1467 * @nb: struct notifier_block * with callback info
1469 * Request no further notification for changes to 'clk' and frees memory
1470 * allocated in clk_notifier_register.
1472 * Returns -EINVAL if called with null arguments; otherwise, passes
1473 * along the return value of srcu_notifier_chain_unregister().
1475 int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb)
1477 struct clk_notifier *cn = NULL;
1483 mutex_lock(&prepare_lock);
1485 list_for_each_entry(cn, &clk_notifier_list, node)
1489 if (cn->clk == clk) {
1490 ret = srcu_notifier_chain_unregister(&cn->notifier_head, nb);
1492 clk->notifier_count--;
1494 /* XXX the notifier code should handle this better */
1495 if (!cn->notifier_head.head) {
1496 srcu_cleanup_notifier_head(&cn->notifier_head);
1504 mutex_unlock(&prepare_lock);
1508 EXPORT_SYMBOL_GPL(clk_notifier_unregister);