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 /* caller must hold prepare_lock */
200 static void clk_disable_unused_subtree(struct clk *clk)
203 struct hlist_node *tmp;
209 hlist_for_each_entry(child, tmp, &clk->children, child_node)
210 clk_disable_unused_subtree(child);
212 spin_lock_irqsave(&enable_lock, flags);
214 if (clk->enable_count)
217 if (clk->flags & CLK_IGNORE_UNUSED)
220 if (__clk_is_enabled(clk) && clk->ops->disable)
221 clk->ops->disable(clk->hw);
224 spin_unlock_irqrestore(&enable_lock, flags);
230 static int clk_disable_unused(void)
233 struct hlist_node *tmp;
235 mutex_lock(&prepare_lock);
237 hlist_for_each_entry(clk, tmp, &clk_root_list, child_node)
238 clk_disable_unused_subtree(clk);
240 hlist_for_each_entry(clk, tmp, &clk_orphan_list, child_node)
241 clk_disable_unused_subtree(clk);
243 mutex_unlock(&prepare_lock);
247 late_initcall(clk_disable_unused);
249 /*** helper functions ***/
251 inline const char *__clk_get_name(struct clk *clk)
253 return !clk ? NULL : clk->name;
256 inline struct clk_hw *__clk_get_hw(struct clk *clk)
258 return !clk ? NULL : clk->hw;
261 inline u8 __clk_get_num_parents(struct clk *clk)
263 return !clk ? -EINVAL : clk->num_parents;
266 inline struct clk *__clk_get_parent(struct clk *clk)
268 return !clk ? NULL : clk->parent;
271 inline int __clk_get_enable_count(struct clk *clk)
273 return !clk ? -EINVAL : clk->enable_count;
276 inline int __clk_get_prepare_count(struct clk *clk)
278 return !clk ? -EINVAL : clk->prepare_count;
281 unsigned long __clk_get_rate(struct clk *clk)
292 if (clk->flags & CLK_IS_ROOT)
302 inline unsigned long __clk_get_flags(struct clk *clk)
304 return !clk ? -EINVAL : clk->flags;
307 int __clk_is_enabled(struct clk *clk)
315 * .is_enabled is only mandatory for clocks that gate
316 * fall back to software usage counter if .is_enabled is missing
318 if (!clk->ops->is_enabled) {
319 ret = clk->enable_count ? 1 : 0;
323 ret = clk->ops->is_enabled(clk->hw);
328 static struct clk *__clk_lookup_subtree(const char *name, struct clk *clk)
332 struct hlist_node *tmp;
334 if (!strcmp(clk->name, name))
337 hlist_for_each_entry(child, tmp, &clk->children, child_node) {
338 ret = __clk_lookup_subtree(name, child);
346 struct clk *__clk_lookup(const char *name)
348 struct clk *root_clk;
350 struct hlist_node *tmp;
355 /* search the 'proper' clk tree first */
356 hlist_for_each_entry(root_clk, tmp, &clk_root_list, child_node) {
357 ret = __clk_lookup_subtree(name, root_clk);
362 /* if not found, then search the orphan tree */
363 hlist_for_each_entry(root_clk, tmp, &clk_orphan_list, child_node) {
364 ret = __clk_lookup_subtree(name, root_clk);
374 void __clk_unprepare(struct clk *clk)
379 if (WARN_ON(clk->prepare_count == 0))
382 if (--clk->prepare_count > 0)
385 WARN_ON(clk->enable_count > 0);
387 if (clk->ops->unprepare)
388 clk->ops->unprepare(clk->hw);
390 __clk_unprepare(clk->parent);
394 * clk_unprepare - undo preparation of a clock source
395 * @clk: the clk being unprepare
397 * clk_unprepare may sleep, which differentiates it from clk_disable. In a
398 * simple case, clk_unprepare can be used instead of clk_disable to gate a clk
399 * if the operation may sleep. One example is a clk which is accessed over
400 * I2c. In the complex case a clk gate operation may require a fast and a slow
401 * part. It is this reason that clk_unprepare and clk_disable are not mutually
402 * exclusive. In fact clk_disable must be called before clk_unprepare.
404 void clk_unprepare(struct clk *clk)
406 mutex_lock(&prepare_lock);
407 __clk_unprepare(clk);
408 mutex_unlock(&prepare_lock);
410 EXPORT_SYMBOL_GPL(clk_unprepare);
412 int __clk_prepare(struct clk *clk)
419 if (clk->prepare_count == 0) {
420 ret = __clk_prepare(clk->parent);
424 if (clk->ops->prepare) {
425 ret = clk->ops->prepare(clk->hw);
427 __clk_unprepare(clk->parent);
433 clk->prepare_count++;
439 * clk_prepare - prepare a clock source
440 * @clk: the clk being prepared
442 * clk_prepare may sleep, which differentiates it from clk_enable. In a simple
443 * case, clk_prepare can be used instead of clk_enable to ungate a clk if the
444 * operation may sleep. One example is a clk which is accessed over I2c. In
445 * the complex case a clk ungate operation may require a fast and a slow part.
446 * It is this reason that clk_prepare and clk_enable are not mutually
447 * exclusive. In fact clk_prepare must be called before clk_enable.
448 * Returns 0 on success, -EERROR otherwise.
450 int clk_prepare(struct clk *clk)
454 mutex_lock(&prepare_lock);
455 ret = __clk_prepare(clk);
456 mutex_unlock(&prepare_lock);
460 EXPORT_SYMBOL_GPL(clk_prepare);
462 static void __clk_disable(struct clk *clk)
467 if (WARN_ON(clk->enable_count == 0))
470 if (--clk->enable_count > 0)
473 if (clk->ops->disable)
474 clk->ops->disable(clk->hw);
476 __clk_disable(clk->parent);
480 * clk_disable - gate a clock
481 * @clk: the clk being gated
483 * clk_disable must not sleep, which differentiates it from clk_unprepare. In
484 * a simple case, clk_disable can be used instead of clk_unprepare to gate a
485 * clk if the operation is fast and will never sleep. One example is a
486 * SoC-internal clk which is controlled via simple register writes. In the
487 * complex case a clk gate operation may require a fast and a slow part. It is
488 * this reason that clk_unprepare and clk_disable are not mutually exclusive.
489 * In fact clk_disable must be called before clk_unprepare.
491 void clk_disable(struct clk *clk)
495 spin_lock_irqsave(&enable_lock, flags);
497 spin_unlock_irqrestore(&enable_lock, flags);
499 EXPORT_SYMBOL_GPL(clk_disable);
501 static int __clk_enable(struct clk *clk)
508 if (WARN_ON(clk->prepare_count == 0))
511 if (clk->enable_count == 0) {
512 ret = __clk_enable(clk->parent);
517 if (clk->ops->enable) {
518 ret = clk->ops->enable(clk->hw);
520 __clk_disable(clk->parent);
531 * clk_enable - ungate a clock
532 * @clk: the clk being ungated
534 * clk_enable must not sleep, which differentiates it from clk_prepare. In a
535 * simple case, clk_enable can be used instead of clk_prepare to ungate a clk
536 * if the operation will never sleep. One example is a SoC-internal clk which
537 * is controlled via simple register writes. In the complex case a clk ungate
538 * operation may require a fast and a slow part. It is this reason that
539 * clk_enable and clk_prepare are not mutually exclusive. In fact clk_prepare
540 * must be called before clk_enable. Returns 0 on success, -EERROR
543 int clk_enable(struct clk *clk)
548 spin_lock_irqsave(&enable_lock, flags);
549 ret = __clk_enable(clk);
550 spin_unlock_irqrestore(&enable_lock, flags);
554 EXPORT_SYMBOL_GPL(clk_enable);
557 * clk_get_rate - return the rate of clk
558 * @clk: the clk whose rate is being returned
560 * Simply returns the cached rate of the clk. Does not query the hardware. If
561 * clk is NULL then returns 0.
563 unsigned long clk_get_rate(struct clk *clk)
567 mutex_lock(&prepare_lock);
568 rate = __clk_get_rate(clk);
569 mutex_unlock(&prepare_lock);
573 EXPORT_SYMBOL_GPL(clk_get_rate);
576 * __clk_round_rate - round the given rate for a clk
577 * @clk: round the rate of this clock
579 * Caller must hold prepare_lock. Useful for clk_ops such as .set_rate
581 unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
583 unsigned long parent_rate = 0;
588 if (!clk->ops->round_rate) {
589 if (clk->flags & CLK_SET_RATE_PARENT)
590 return __clk_round_rate(clk->parent, rate);
596 parent_rate = clk->parent->rate;
598 return clk->ops->round_rate(clk->hw, rate, &parent_rate);
602 * clk_round_rate - round the given rate for a clk
603 * @clk: the clk for which we are rounding a rate
604 * @rate: the rate which is to be rounded
606 * Takes in a rate as input and rounds it to a rate that the clk can actually
607 * use which is then returned. If clk doesn't support round_rate operation
608 * then the parent rate is returned.
610 long clk_round_rate(struct clk *clk, unsigned long rate)
614 mutex_lock(&prepare_lock);
615 ret = __clk_round_rate(clk, rate);
616 mutex_unlock(&prepare_lock);
620 EXPORT_SYMBOL_GPL(clk_round_rate);
623 * __clk_notify - call clk notifier chain
624 * @clk: struct clk * that is changing rate
625 * @msg: clk notifier type (see include/linux/clk.h)
626 * @old_rate: old clk rate
627 * @new_rate: new clk rate
629 * Triggers a notifier call chain on the clk rate-change notification
630 * for 'clk'. Passes a pointer to the struct clk and the previous
631 * and current rates to the notifier callback. Intended to be called by
632 * internal clock code only. Returns NOTIFY_DONE from the last driver
633 * called if all went well, or NOTIFY_STOP or NOTIFY_BAD immediately if
634 * a driver returns that.
636 static int __clk_notify(struct clk *clk, unsigned long msg,
637 unsigned long old_rate, unsigned long new_rate)
639 struct clk_notifier *cn;
640 struct clk_notifier_data cnd;
641 int ret = NOTIFY_DONE;
644 cnd.old_rate = old_rate;
645 cnd.new_rate = new_rate;
647 list_for_each_entry(cn, &clk_notifier_list, node) {
648 if (cn->clk == clk) {
649 ret = srcu_notifier_call_chain(&cn->notifier_head, msg,
660 * @clk: first clk in the subtree
661 * @msg: notification type (see include/linux/clk.h)
663 * Walks the subtree of clks starting with clk and recalculates rates as it
664 * goes. Note that if a clk does not implement the .recalc_rate callback then
665 * it is assumed that the clock will take on the rate of it's parent.
667 * clk_recalc_rates also propagates the POST_RATE_CHANGE notification,
670 * Caller must hold prepare_lock.
672 static void __clk_recalc_rates(struct clk *clk, unsigned long msg)
674 unsigned long old_rate;
675 unsigned long parent_rate = 0;
676 struct hlist_node *tmp;
679 old_rate = clk->rate;
682 parent_rate = clk->parent->rate;
684 if (clk->ops->recalc_rate)
685 clk->rate = clk->ops->recalc_rate(clk->hw, parent_rate);
687 clk->rate = parent_rate;
690 * ignore NOTIFY_STOP and NOTIFY_BAD return values for POST_RATE_CHANGE
691 * & ABORT_RATE_CHANGE notifiers
693 if (clk->notifier_count && msg)
694 __clk_notify(clk, msg, old_rate, clk->rate);
696 hlist_for_each_entry(child, tmp, &clk->children, child_node)
697 __clk_recalc_rates(child, msg);
701 * __clk_speculate_rates
702 * @clk: first clk in the subtree
703 * @parent_rate: the "future" rate of clk's parent
705 * Walks the subtree of clks starting with clk, speculating rates as it
706 * goes and firing off PRE_RATE_CHANGE notifications as necessary.
708 * Unlike clk_recalc_rates, clk_speculate_rates exists only for sending
709 * pre-rate change notifications and returns early if no clks in the
710 * subtree have subscribed to the notifications. Note that if a clk does not
711 * implement the .recalc_rate callback then it is assumed that the clock will
712 * take on the rate of it's parent.
714 * Caller must hold prepare_lock.
716 static int __clk_speculate_rates(struct clk *clk, unsigned long parent_rate)
718 struct hlist_node *tmp;
720 unsigned long new_rate;
721 int ret = NOTIFY_DONE;
723 if (clk->ops->recalc_rate)
724 new_rate = clk->ops->recalc_rate(clk->hw, parent_rate);
726 new_rate = parent_rate;
728 /* abort the rate change if a driver returns NOTIFY_BAD */
729 if (clk->notifier_count)
730 ret = __clk_notify(clk, PRE_RATE_CHANGE, clk->rate, new_rate);
732 if (ret == NOTIFY_BAD)
735 hlist_for_each_entry(child, tmp, &clk->children, child_node) {
736 ret = __clk_speculate_rates(child, new_rate);
737 if (ret == NOTIFY_BAD)
745 static void clk_calc_subtree(struct clk *clk, unsigned long new_rate)
748 struct hlist_node *tmp;
750 clk->new_rate = new_rate;
752 hlist_for_each_entry(child, tmp, &clk->children, child_node) {
753 if (child->ops->recalc_rate)
754 child->new_rate = child->ops->recalc_rate(child->hw, new_rate);
756 child->new_rate = new_rate;
757 clk_calc_subtree(child, child->new_rate);
762 * calculate the new rates returning the topmost clock that has to be
765 static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)
767 struct clk *top = clk;
768 unsigned long best_parent_rate = 0;
769 unsigned long new_rate;
772 if (IS_ERR_OR_NULL(clk))
775 /* save parent rate, if it exists */
777 best_parent_rate = clk->parent->rate;
779 /* never propagate up to the parent */
780 if (!(clk->flags & CLK_SET_RATE_PARENT)) {
781 if (!clk->ops->round_rate) {
782 clk->new_rate = clk->rate;
785 new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
789 /* need clk->parent from here on out */
791 pr_debug("%s: %s has NULL parent\n", __func__, clk->name);
795 if (!clk->ops->round_rate) {
796 top = clk_calc_new_rates(clk->parent, rate);
797 new_rate = clk->parent->new_rate;
802 new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
804 if (best_parent_rate != clk->parent->rate) {
805 top = clk_calc_new_rates(clk->parent, best_parent_rate);
811 clk_calc_subtree(clk, new_rate);
817 * Notify about rate changes in a subtree. Always walk down the whole tree
818 * so that in case of an error we can walk down the whole tree again and
821 static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long event)
823 struct hlist_node *tmp;
824 struct clk *child, *fail_clk = NULL;
825 int ret = NOTIFY_DONE;
827 if (clk->rate == clk->new_rate)
830 if (clk->notifier_count) {
831 ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
832 if (ret == NOTIFY_BAD)
836 hlist_for_each_entry(child, tmp, &clk->children, child_node) {
837 clk = clk_propagate_rate_change(child, event);
846 * walk down a subtree and set the new rates notifying the rate
849 static void clk_change_rate(struct clk *clk)
852 unsigned long old_rate;
853 struct hlist_node *tmp;
855 old_rate = clk->rate;
857 if (clk->ops->set_rate)
858 clk->ops->set_rate(clk->hw, clk->new_rate, clk->parent->rate);
860 if (clk->ops->recalc_rate)
861 clk->rate = clk->ops->recalc_rate(clk->hw,
864 clk->rate = clk->parent->rate;
866 if (clk->notifier_count && old_rate != clk->rate)
867 __clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate);
869 hlist_for_each_entry(child, tmp, &clk->children, child_node)
870 clk_change_rate(child);
874 * clk_set_rate - specify a new rate for clk
875 * @clk: the clk whose rate is being changed
876 * @rate: the new rate for clk
878 * In the simplest case clk_set_rate will only adjust the rate of clk.
880 * Setting the CLK_SET_RATE_PARENT flag allows the rate change operation to
881 * propagate up to clk's parent; whether or not this happens depends on the
882 * outcome of clk's .round_rate implementation. If *parent_rate is unchanged
883 * after calling .round_rate then upstream parent propagation is ignored. If
884 * *parent_rate comes back with a new rate for clk's parent then we propagate
885 * up to clk's parent and set it's rate. Upward propagation will continue
886 * until either a clk does not support the CLK_SET_RATE_PARENT flag or
887 * .round_rate stops requesting changes to clk's parent_rate.
889 * Rate changes are accomplished via tree traversal that also recalculates the
890 * rates for the clocks and fires off POST_RATE_CHANGE notifiers.
892 * Returns 0 on success, -EERROR otherwise.
894 int clk_set_rate(struct clk *clk, unsigned long rate)
896 struct clk *top, *fail_clk;
899 /* prevent racing with updates to the clock topology */
900 mutex_lock(&prepare_lock);
902 /* bail early if nothing to do */
903 if (rate == clk->rate)
906 if ((clk->flags & CLK_SET_RATE_GATE) && clk->prepare_count) {
911 /* calculate new rates and get the topmost changed clock */
912 top = clk_calc_new_rates(clk, rate);
918 /* notify that we are about to change rates */
919 fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE);
921 pr_warn("%s: failed to set %s rate\n", __func__,
923 clk_propagate_rate_change(top, ABORT_RATE_CHANGE);
928 /* change the rates */
929 clk_change_rate(top);
931 mutex_unlock(&prepare_lock);
935 mutex_unlock(&prepare_lock);
939 EXPORT_SYMBOL_GPL(clk_set_rate);
942 * clk_get_parent - return the parent of a clk
943 * @clk: the clk whose parent gets returned
945 * Simply returns clk->parent. Returns NULL if clk is NULL.
947 struct clk *clk_get_parent(struct clk *clk)
951 mutex_lock(&prepare_lock);
952 parent = __clk_get_parent(clk);
953 mutex_unlock(&prepare_lock);
957 EXPORT_SYMBOL_GPL(clk_get_parent);
960 * .get_parent is mandatory for clocks with multiple possible parents. It is
961 * optional for single-parent clocks. Always call .get_parent if it is
962 * available and WARN if it is missing for multi-parent clocks.
964 * For single-parent clocks without .get_parent, first check to see if the
965 * .parents array exists, and if so use it to avoid an expensive tree
966 * traversal. If .parents does not exist then walk the tree with __clk_lookup.
968 static struct clk *__clk_init_parent(struct clk *clk)
970 struct clk *ret = NULL;
973 /* handle the trivial cases */
975 if (!clk->num_parents)
978 if (clk->num_parents == 1) {
979 if (IS_ERR_OR_NULL(clk->parent))
980 ret = clk->parent = __clk_lookup(clk->parent_names[0]);
985 if (!clk->ops->get_parent) {
986 WARN(!clk->ops->get_parent,
987 "%s: multi-parent clocks must implement .get_parent\n",
993 * Do our best to cache parent clocks in clk->parents. This prevents
994 * unnecessary and expensive calls to __clk_lookup. We don't set
995 * clk->parent here; that is done by the calling function
998 index = clk->ops->get_parent(clk->hw);
1002 kmalloc((sizeof(struct clk*) * clk->num_parents),
1006 ret = __clk_lookup(clk->parent_names[index]);
1007 else if (!clk->parents[index])
1008 ret = clk->parents[index] =
1009 __clk_lookup(clk->parent_names[index]);
1011 ret = clk->parents[index];
1017 void __clk_reparent(struct clk *clk, struct clk *new_parent)
1019 #ifdef CONFIG_COMMON_CLK_DEBUG
1021 struct dentry *new_parent_d;
1024 if (!clk || !new_parent)
1027 hlist_del(&clk->child_node);
1030 hlist_add_head(&clk->child_node, &new_parent->children);
1032 hlist_add_head(&clk->child_node, &clk_orphan_list);
1034 #ifdef CONFIG_COMMON_CLK_DEBUG
1039 new_parent_d = new_parent->dentry;
1041 new_parent_d = orphandir;
1043 d = debugfs_rename(clk->dentry->d_parent, clk->dentry,
1044 new_parent_d, clk->name);
1048 pr_debug("%s: failed to rename debugfs entry for %s\n",
1049 __func__, clk->name);
1053 clk->parent = new_parent;
1055 __clk_recalc_rates(clk, POST_RATE_CHANGE);
1058 static int __clk_set_parent(struct clk *clk, struct clk *parent)
1060 struct clk *old_parent;
1061 unsigned long flags;
1065 old_parent = clk->parent;
1067 /* find index of new parent clock using cached parent ptrs */
1068 for (i = 0; i < clk->num_parents; i++)
1069 if (clk->parents[i] == parent)
1073 * find index of new parent clock using string name comparison
1074 * also try to cache the parent to avoid future calls to __clk_lookup
1076 if (i == clk->num_parents)
1077 for (i = 0; i < clk->num_parents; i++)
1078 if (!strcmp(clk->parent_names[i], parent->name)) {
1079 clk->parents[i] = __clk_lookup(parent->name);
1083 if (i == clk->num_parents) {
1084 pr_debug("%s: clock %s is not a possible parent of clock %s\n",
1085 __func__, parent->name, clk->name);
1089 /* migrate prepare and enable */
1090 if (clk->prepare_count)
1091 __clk_prepare(parent);
1093 /* FIXME replace with clk_is_enabled(clk) someday */
1094 spin_lock_irqsave(&enable_lock, flags);
1095 if (clk->enable_count)
1096 __clk_enable(parent);
1097 spin_unlock_irqrestore(&enable_lock, flags);
1099 /* change clock input source */
1100 ret = clk->ops->set_parent(clk->hw, i);
1102 /* clean up old prepare and enable */
1103 spin_lock_irqsave(&enable_lock, flags);
1104 if (clk->enable_count)
1105 __clk_disable(old_parent);
1106 spin_unlock_irqrestore(&enable_lock, flags);
1108 if (clk->prepare_count)
1109 __clk_unprepare(old_parent);
1116 * clk_set_parent - switch the parent of a mux clk
1117 * @clk: the mux clk whose input we are switching
1118 * @parent: the new input to clk
1120 * Re-parent clk to use parent as it's new input source. If clk has the
1121 * CLK_SET_PARENT_GATE flag set then clk must be gated for this
1122 * operation to succeed. After successfully changing clk's parent
1123 * clk_set_parent will update the clk topology, sysfs topology and
1124 * propagate rate recalculation via __clk_recalc_rates. Returns 0 on
1125 * success, -EERROR otherwise.
1127 int clk_set_parent(struct clk *clk, struct clk *parent)
1131 if (!clk || !clk->ops)
1134 if (!clk->ops->set_parent)
1137 /* prevent racing with updates to the clock topology */
1138 mutex_lock(&prepare_lock);
1140 if (clk->parent == parent)
1143 /* propagate PRE_RATE_CHANGE notifications */
1144 if (clk->notifier_count)
1145 ret = __clk_speculate_rates(clk, parent->rate);
1147 /* abort if a driver objects */
1148 if (ret == NOTIFY_STOP)
1151 /* only re-parent if the clock is not in use */
1152 if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count)
1155 ret = __clk_set_parent(clk, parent);
1157 /* propagate ABORT_RATE_CHANGE if .set_parent failed */
1159 __clk_recalc_rates(clk, ABORT_RATE_CHANGE);
1163 /* propagate rate recalculation downstream */
1164 __clk_reparent(clk, parent);
1167 mutex_unlock(&prepare_lock);
1171 EXPORT_SYMBOL_GPL(clk_set_parent);
1174 * __clk_init - initialize the data structures in a struct clk
1175 * @dev: device initializing this clk, placeholder for now
1176 * @clk: clk being initialized
1178 * Initializes the lists in struct clk, queries the hardware for the
1179 * parent and rate and sets them both.
1181 int __clk_init(struct device *dev, struct clk *clk)
1185 struct hlist_node *tmp, *tmp2;
1190 mutex_lock(&prepare_lock);
1192 /* check to see if a clock with this name is already registered */
1193 if (__clk_lookup(clk->name)) {
1194 pr_debug("%s: clk %s already initialized\n",
1195 __func__, clk->name);
1200 /* check that clk_ops are sane. See Documentation/clk.txt */
1201 if (clk->ops->set_rate &&
1202 !(clk->ops->round_rate && clk->ops->recalc_rate)) {
1203 pr_warning("%s: %s must implement .round_rate & .recalc_rate\n",
1204 __func__, clk->name);
1209 if (clk->ops->set_parent && !clk->ops->get_parent) {
1210 pr_warning("%s: %s must implement .get_parent & .set_parent\n",
1211 __func__, clk->name);
1216 /* throw a WARN if any entries in parent_names are NULL */
1217 for (i = 0; i < clk->num_parents; i++)
1218 WARN(!clk->parent_names[i],
1219 "%s: invalid NULL in %s's .parent_names\n",
1220 __func__, clk->name);
1223 * Allocate an array of struct clk *'s to avoid unnecessary string
1224 * look-ups of clk's possible parents. This can fail for clocks passed
1225 * in to clk_init during early boot; thus any access to clk->parents[]
1226 * must always check for a NULL pointer and try to populate it if
1229 * If clk->parents is not NULL we skip this entire block. This allows
1230 * for clock drivers to statically initialize clk->parents.
1232 if (clk->num_parents && !clk->parents) {
1233 clk->parents = kmalloc((sizeof(struct clk*) * clk->num_parents),
1236 * __clk_lookup returns NULL for parents that have not been
1237 * clk_init'd; thus any access to clk->parents[] must check
1238 * for a NULL pointer. We can always perform lazy lookups for
1239 * missing parents later on.
1242 for (i = 0; i < clk->num_parents; i++)
1244 __clk_lookup(clk->parent_names[i]);
1247 clk->parent = __clk_init_parent(clk);
1250 * Populate clk->parent if parent has already been __clk_init'd. If
1251 * parent has not yet been __clk_init'd then place clk in the orphan
1252 * list. If clk has set the CLK_IS_ROOT flag then place it in the root
1255 * Every time a new clk is clk_init'd then we walk the list of orphan
1256 * clocks and re-parent any that are children of the clock currently
1260 hlist_add_head(&clk->child_node,
1261 &clk->parent->children);
1262 else if (clk->flags & CLK_IS_ROOT)
1263 hlist_add_head(&clk->child_node, &clk_root_list);
1265 hlist_add_head(&clk->child_node, &clk_orphan_list);
1268 * Set clk's rate. The preferred method is to use .recalc_rate. For
1269 * simple clocks and lazy developers the default fallback is to use the
1270 * parent's rate. If a clock doesn't have a parent (or is orphaned)
1271 * then rate is set to zero.
1273 if (clk->ops->recalc_rate)
1274 clk->rate = clk->ops->recalc_rate(clk->hw,
1275 __clk_get_rate(clk->parent));
1276 else if (clk->parent)
1277 clk->rate = clk->parent->rate;
1282 * walk the list of orphan clocks and reparent any that are children of
1285 hlist_for_each_entry_safe(orphan, tmp, tmp2, &clk_orphan_list, child_node)
1286 for (i = 0; i < orphan->num_parents; i++)
1287 if (!strcmp(clk->name, orphan->parent_names[i])) {
1288 __clk_reparent(orphan, clk);
1293 * optional platform-specific magic
1295 * The .init callback is not used by any of the basic clock types, but
1296 * exists for weird hardware that must perform initialization magic.
1297 * Please consider other ways of solving initialization problems before
1298 * using this callback, as it's use is discouraged.
1301 clk->ops->init(clk->hw);
1303 clk_debug_register(clk);
1306 mutex_unlock(&prepare_lock);
1312 * __clk_register - register a clock and return a cookie.
1314 * Same as clk_register, except that the .clk field inside hw shall point to a
1315 * preallocated (generally statically allocated) struct clk. None of the fields
1316 * of the struct clk need to be initialized.
1318 * The data pointed to by .init and .clk field shall NOT be marked as init
1321 * __clk_register is only exposed via clk-private.h and is intended for use with
1322 * very large numbers of clocks that need to be statically initialized. It is
1323 * a layering violation to include clk-private.h from any code which implements
1324 * a clock's .ops; as such any statically initialized clock data MUST be in a
1325 * separate C file from the logic that implements it's operations. Returns 0
1326 * on success, otherwise an error code.
1328 struct clk *__clk_register(struct device *dev, struct clk_hw *hw)
1334 clk->name = hw->init->name;
1335 clk->ops = hw->init->ops;
1337 clk->flags = hw->init->flags;
1338 clk->parent_names = hw->init->parent_names;
1339 clk->num_parents = hw->init->num_parents;
1341 ret = __clk_init(dev, clk);
1343 return ERR_PTR(ret);
1347 EXPORT_SYMBOL_GPL(__clk_register);
1350 * clk_register - allocate a new clock, register it and return an opaque cookie
1351 * @dev: device that is registering this clock
1352 * @hw: link to hardware-specific clock data
1354 * clk_register is the primary interface for populating the clock tree with new
1355 * clock nodes. It returns a pointer to the newly allocated struct clk which
1356 * cannot be dereferenced by driver code but may be used in conjuction with the
1357 * rest of the clock API. In the event of an error clk_register will return an
1358 * error code; drivers must test for an error code after calling clk_register.
1360 struct clk *clk_register(struct device *dev, struct clk_hw *hw)
1365 clk = kzalloc(sizeof(*clk), GFP_KERNEL);
1367 pr_err("%s: could not allocate clk\n", __func__);
1372 clk->name = kstrdup(hw->init->name, GFP_KERNEL);
1374 pr_err("%s: could not allocate clk->name\n", __func__);
1378 clk->ops = hw->init->ops;
1380 clk->flags = hw->init->flags;
1381 clk->num_parents = hw->init->num_parents;
1384 /* allocate local copy in case parent_names is __initdata */
1385 clk->parent_names = kzalloc((sizeof(char*) * clk->num_parents),
1388 if (!clk->parent_names) {
1389 pr_err("%s: could not allocate clk->parent_names\n", __func__);
1391 goto fail_parent_names;
1395 /* copy each string name in case parent_names is __initdata */
1396 for (i = 0; i < clk->num_parents; i++) {
1397 clk->parent_names[i] = kstrdup(hw->init->parent_names[i],
1399 if (!clk->parent_names[i]) {
1400 pr_err("%s: could not copy parent_names\n", __func__);
1402 goto fail_parent_names_copy;
1406 ret = __clk_init(dev, clk);
1410 fail_parent_names_copy:
1412 kfree(clk->parent_names[i]);
1413 kfree(clk->parent_names);
1419 return ERR_PTR(ret);
1421 EXPORT_SYMBOL_GPL(clk_register);
1424 * clk_unregister - unregister a currently registered clock
1425 * @clk: clock to unregister
1427 * Currently unimplemented.
1429 void clk_unregister(struct clk *clk) {}
1430 EXPORT_SYMBOL_GPL(clk_unregister);
1432 /*** clk rate change notifiers ***/
1435 * clk_notifier_register - add a clk rate change notifier
1436 * @clk: struct clk * to watch
1437 * @nb: struct notifier_block * with callback info
1439 * Request notification when clk's rate changes. This uses an SRCU
1440 * notifier because we want it to block and notifier unregistrations are
1441 * uncommon. The callbacks associated with the notifier must not
1442 * re-enter into the clk framework by calling any top-level clk APIs;
1443 * this will cause a nested prepare_lock mutex.
1445 * Pre-change notifier callbacks will be passed the current, pre-change
1446 * rate of the clk via struct clk_notifier_data.old_rate. The new,
1447 * post-change rate of the clk is passed via struct
1448 * clk_notifier_data.new_rate.
1450 * Post-change notifiers will pass the now-current, post-change rate of
1451 * the clk in both struct clk_notifier_data.old_rate and struct
1452 * clk_notifier_data.new_rate.
1454 * Abort-change notifiers are effectively the opposite of pre-change
1455 * notifiers: the original pre-change clk rate is passed in via struct
1456 * clk_notifier_data.new_rate and the failed post-change rate is passed
1457 * in via struct clk_notifier_data.old_rate.
1459 * clk_notifier_register() must be called from non-atomic context.
1460 * Returns -EINVAL if called with null arguments, -ENOMEM upon
1461 * allocation failure; otherwise, passes along the return value of
1462 * srcu_notifier_chain_register().
1464 int clk_notifier_register(struct clk *clk, struct notifier_block *nb)
1466 struct clk_notifier *cn;
1472 mutex_lock(&prepare_lock);
1474 /* search the list of notifiers for this clk */
1475 list_for_each_entry(cn, &clk_notifier_list, node)
1479 /* if clk wasn't in the notifier list, allocate new clk_notifier */
1480 if (cn->clk != clk) {
1481 cn = kzalloc(sizeof(struct clk_notifier), GFP_KERNEL);
1486 srcu_init_notifier_head(&cn->notifier_head);
1488 list_add(&cn->node, &clk_notifier_list);
1491 ret = srcu_notifier_chain_register(&cn->notifier_head, nb);
1493 clk->notifier_count++;
1496 mutex_unlock(&prepare_lock);
1500 EXPORT_SYMBOL_GPL(clk_notifier_register);
1503 * clk_notifier_unregister - remove a clk rate change notifier
1504 * @clk: struct clk *
1505 * @nb: struct notifier_block * with callback info
1507 * Request no further notification for changes to 'clk' and frees memory
1508 * allocated in clk_notifier_register.
1510 * Returns -EINVAL if called with null arguments; otherwise, passes
1511 * along the return value of srcu_notifier_chain_unregister().
1513 int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb)
1515 struct clk_notifier *cn = NULL;
1521 mutex_lock(&prepare_lock);
1523 list_for_each_entry(cn, &clk_notifier_list, node)
1527 if (cn->clk == clk) {
1528 ret = srcu_notifier_chain_unregister(&cn->notifier_head, nb);
1530 clk->notifier_count--;
1532 /* XXX the notifier code should handle this better */
1533 if (!cn->notifier_head.head) {
1534 srcu_cleanup_notifier_head(&cn->notifier_head);
1542 mutex_unlock(&prepare_lock);
1546 EXPORT_SYMBOL_GPL(clk_notifier_unregister);