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.
1190 void __clk_init(struct device
*dev
, struct clk
*clk
)
1194 struct hlist_node
*tmp
, *tmp2
;
1199 mutex_lock(&prepare_lock
);
1201 /* check to see if a clock with this name is already registered */
1202 if (__clk_lookup(clk
->name
))
1205 /* check that clk_ops are sane. See Documentation/clk.txt */
1206 if (clk
->ops
->set_rate
&&
1207 !(clk
->ops
->round_rate
&& clk
->ops
->recalc_rate
)) {
1208 pr_warning("%s: %s must implement .round_rate & .recalc_rate\n",
1209 __func__
, clk
->name
);
1213 if (clk
->ops
->set_parent
&& !clk
->ops
->get_parent
) {
1214 pr_warning("%s: %s must implement .get_parent & .set_parent\n",
1215 __func__
, clk
->name
);
1219 /* throw a WARN if any entries in parent_names are NULL */
1220 for (i
= 0; i
< clk
->num_parents
; i
++)
1221 WARN(!clk
->parent_names
[i
],
1222 "%s: invalid NULL in %s's .parent_names\n",
1223 __func__
, clk
->name
);
1226 * Allocate an array of struct clk *'s to avoid unnecessary string
1227 * look-ups of clk's possible parents. This can fail for clocks passed
1228 * in to clk_init during early boot; thus any access to clk->parents[]
1229 * must always check for a NULL pointer and try to populate it if
1232 * If clk->parents is not NULL we skip this entire block. This allows
1233 * for clock drivers to statically initialize clk->parents.
1235 if (clk
->num_parents
&& !clk
->parents
) {
1236 clk
->parents
= kmalloc((sizeof(struct clk
*) * clk
->num_parents
),
1239 * __clk_lookup returns NULL for parents that have not been
1240 * clk_init'd; thus any access to clk->parents[] must check
1241 * for a NULL pointer. We can always perform lazy lookups for
1242 * missing parents later on.
1245 for (i
= 0; i
< clk
->num_parents
; i
++)
1247 __clk_lookup(clk
->parent_names
[i
]);
1250 clk
->parent
= __clk_init_parent(clk
);
1253 * Populate clk->parent if parent has already been __clk_init'd. If
1254 * parent has not yet been __clk_init'd then place clk in the orphan
1255 * list. If clk has set the CLK_IS_ROOT flag then place it in the root
1258 * Every time a new clk is clk_init'd then we walk the list of orphan
1259 * clocks and re-parent any that are children of the clock currently
1263 hlist_add_head(&clk
->child_node
,
1264 &clk
->parent
->children
);
1265 else if (clk
->flags
& CLK_IS_ROOT
)
1266 hlist_add_head(&clk
->child_node
, &clk_root_list
);
1268 hlist_add_head(&clk
->child_node
, &clk_orphan_list
);
1271 * Set clk's rate. The preferred method is to use .recalc_rate. For
1272 * simple clocks and lazy developers the default fallback is to use the
1273 * parent's rate. If a clock doesn't have a parent (or is orphaned)
1274 * then rate is set to zero.
1276 if (clk
->ops
->recalc_rate
)
1277 clk
->rate
= clk
->ops
->recalc_rate(clk
->hw
,
1278 __clk_get_rate(clk
->parent
));
1279 else if (clk
->parent
)
1280 clk
->rate
= clk
->parent
->rate
;
1285 * walk the list of orphan clocks and reparent any that are children of
1288 hlist_for_each_entry_safe(orphan
, tmp
, tmp2
, &clk_orphan_list
, child_node
)
1289 for (i
= 0; i
< orphan
->num_parents
; i
++)
1290 if (!strcmp(clk
->name
, orphan
->parent_names
[i
])) {
1291 __clk_reparent(orphan
, clk
);
1296 * optional platform-specific magic
1298 * The .init callback is not used by any of the basic clock types, but
1299 * exists for weird hardware that must perform initialization magic.
1300 * Please consider other ways of solving initialization problems before
1301 * using this callback, as it's use is discouraged.
1304 clk
->ops
->init(clk
->hw
);
1306 clk_debug_register(clk
);
1309 mutex_unlock(&prepare_lock
);
1315 * clk_register - allocate a new clock, register it and return an opaque cookie
1316 * @dev: device that is registering this clock
1318 * @ops: operations this clock supports
1319 * @hw: link to hardware-specific clock data
1320 * @parent_names: array of string names for all possible parents
1321 * @num_parents: number of possible parents
1322 * @flags: framework-level hints and quirks
1324 * clk_register is the primary interface for populating the clock tree with new
1325 * clock nodes. It returns a pointer to the newly allocated struct clk which
1326 * cannot be dereferenced by driver code but may be used in conjuction with the
1327 * rest of the clock API.
1329 struct clk
*clk_register(struct device
*dev
, const char *name
,
1330 const struct clk_ops
*ops
, struct clk_hw
*hw
,
1331 char **parent_names
, u8 num_parents
, unsigned long flags
)
1335 clk
= kzalloc(sizeof(*clk
), GFP_KERNEL
);
1343 clk
->parent_names
= parent_names
;
1344 clk
->num_parents
= num_parents
;
1347 __clk_init(dev
, clk
);
1351 EXPORT_SYMBOL_GPL(clk_register
);
1353 /*** clk rate change notifiers ***/
1356 * clk_notifier_register - add a clk rate change notifier
1357 * @clk: struct clk * to watch
1358 * @nb: struct notifier_block * with callback info
1360 * Request notification when clk's rate changes. This uses an SRCU
1361 * notifier because we want it to block and notifier unregistrations are
1362 * uncommon. The callbacks associated with the notifier must not
1363 * re-enter into the clk framework by calling any top-level clk APIs;
1364 * this will cause a nested prepare_lock mutex.
1366 * Pre-change notifier callbacks will be passed the current, pre-change
1367 * rate of the clk via struct clk_notifier_data.old_rate. The new,
1368 * post-change rate of the clk is passed via struct
1369 * clk_notifier_data.new_rate.
1371 * Post-change notifiers will pass the now-current, post-change rate of
1372 * the clk in both struct clk_notifier_data.old_rate and struct
1373 * clk_notifier_data.new_rate.
1375 * Abort-change notifiers are effectively the opposite of pre-change
1376 * notifiers: the original pre-change clk rate is passed in via struct
1377 * clk_notifier_data.new_rate and the failed post-change rate is passed
1378 * in via struct clk_notifier_data.old_rate.
1380 * clk_notifier_register() must be called from non-atomic context.
1381 * Returns -EINVAL if called with null arguments, -ENOMEM upon
1382 * allocation failure; otherwise, passes along the return value of
1383 * srcu_notifier_chain_register().
1385 int clk_notifier_register(struct clk
*clk
, struct notifier_block
*nb
)
1387 struct clk_notifier
*cn
;
1393 mutex_lock(&prepare_lock
);
1395 /* search the list of notifiers for this clk */
1396 list_for_each_entry(cn
, &clk_notifier_list
, node
)
1400 /* if clk wasn't in the notifier list, allocate new clk_notifier */
1401 if (cn
->clk
!= clk
) {
1402 cn
= kzalloc(sizeof(struct clk_notifier
), GFP_KERNEL
);
1407 srcu_init_notifier_head(&cn
->notifier_head
);
1409 list_add(&cn
->node
, &clk_notifier_list
);
1412 ret
= srcu_notifier_chain_register(&cn
->notifier_head
, nb
);
1414 clk
->notifier_count
++;
1417 mutex_unlock(&prepare_lock
);
1421 EXPORT_SYMBOL_GPL(clk_notifier_register
);
1424 * clk_notifier_unregister - remove a clk rate change notifier
1425 * @clk: struct clk *
1426 * @nb: struct notifier_block * with callback info
1428 * Request no further notification for changes to 'clk' and frees memory
1429 * allocated in clk_notifier_register.
1431 * Returns -EINVAL if called with null arguments; otherwise, passes
1432 * along the return value of srcu_notifier_chain_unregister().
1434 int clk_notifier_unregister(struct clk
*clk
, struct notifier_block
*nb
)
1436 struct clk_notifier
*cn
= NULL
;
1442 mutex_lock(&prepare_lock
);
1444 list_for_each_entry(cn
, &clk_notifier_list
, node
)
1448 if (cn
->clk
== clk
) {
1449 ret
= srcu_notifier_chain_unregister(&cn
->notifier_head
, nb
);
1451 clk
->notifier_count
--;
1453 /* XXX the notifier code should handle this better */
1454 if (!cn
->notifier_head
.head
) {
1455 srcu_cleanup_notifier_head(&cn
->notifier_head
);
1463 mutex_unlock(&prepare_lock
);
1467 EXPORT_SYMBOL_GPL(clk_notifier_unregister
);
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