]>
git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - drivers/clk/clk.c
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; }
197 #endif /* CONFIG_COMMON_CLK_DEBUG */
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
);
250 static inline int clk_disable_unused(struct clk
*clk
) { return 0; }
251 #endif /* CONFIG_COMMON_CLK_DISABLE_UNUSED */
253 /*** helper functions ***/
255 inline const char *__clk_get_name(struct clk
*clk
)
257 return !clk
? NULL
: clk
->name
;
260 inline struct clk_hw
*__clk_get_hw(struct clk
*clk
)
262 return !clk
? NULL
: clk
->hw
;
265 inline u8
__clk_get_num_parents(struct clk
*clk
)
267 return !clk
? -EINVAL
: clk
->num_parents
;
270 inline struct clk
*__clk_get_parent(struct clk
*clk
)
272 return !clk
? NULL
: clk
->parent
;
275 inline int __clk_get_enable_count(struct clk
*clk
)
277 return !clk
? -EINVAL
: clk
->enable_count
;
280 inline int __clk_get_prepare_count(struct clk
*clk
)
282 return !clk
? -EINVAL
: clk
->prepare_count
;
285 unsigned long __clk_get_rate(struct clk
*clk
)
296 if (clk
->flags
& CLK_IS_ROOT
)
306 inline unsigned long __clk_get_flags(struct clk
*clk
)
308 return !clk
? -EINVAL
: clk
->flags
;
311 int __clk_is_enabled(struct clk
*clk
)
319 * .is_enabled is only mandatory for clocks that gate
320 * fall back to software usage counter if .is_enabled is missing
322 if (!clk
->ops
->is_enabled
) {
323 ret
= clk
->enable_count
? 1 : 0;
327 ret
= clk
->ops
->is_enabled(clk
->hw
);
332 static struct clk
*__clk_lookup_subtree(const char *name
, struct clk
*clk
)
336 struct hlist_node
*tmp
;
338 if (!strcmp(clk
->name
, name
))
341 hlist_for_each_entry(child
, tmp
, &clk
->children
, child_node
) {
342 ret
= __clk_lookup_subtree(name
, child
);
350 struct clk
*__clk_lookup(const char *name
)
352 struct clk
*root_clk
;
354 struct hlist_node
*tmp
;
359 /* search the 'proper' clk tree first */
360 hlist_for_each_entry(root_clk
, tmp
, &clk_root_list
, child_node
) {
361 ret
= __clk_lookup_subtree(name
, root_clk
);
366 /* if not found, then search the orphan tree */
367 hlist_for_each_entry(root_clk
, tmp
, &clk_orphan_list
, child_node
) {
368 ret
= __clk_lookup_subtree(name
, root_clk
);
378 void __clk_unprepare(struct clk
*clk
)
383 if (WARN_ON(clk
->prepare_count
== 0))
386 if (--clk
->prepare_count
> 0)
389 WARN_ON(clk
->enable_count
> 0);
391 if (clk
->ops
->unprepare
)
392 clk
->ops
->unprepare(clk
->hw
);
394 __clk_unprepare(clk
->parent
);
398 * clk_unprepare - undo preparation of a clock source
399 * @clk: the clk being unprepare
401 * clk_unprepare may sleep, which differentiates it from clk_disable. In a
402 * simple case, clk_unprepare can be used instead of clk_disable to gate a clk
403 * if the operation may sleep. One example is a clk which is accessed over
404 * I2c. In the complex case a clk gate operation may require a fast and a slow
405 * part. It is this reason that clk_unprepare and clk_disable are not mutually
406 * exclusive. In fact clk_disable must be called before clk_unprepare.
408 void clk_unprepare(struct clk
*clk
)
410 mutex_lock(&prepare_lock
);
411 __clk_unprepare(clk
);
412 mutex_unlock(&prepare_lock
);
414 EXPORT_SYMBOL_GPL(clk_unprepare
);
416 int __clk_prepare(struct clk
*clk
)
423 if (clk
->prepare_count
== 0) {
424 ret
= __clk_prepare(clk
->parent
);
428 if (clk
->ops
->prepare
) {
429 ret
= clk
->ops
->prepare(clk
->hw
);
431 __clk_unprepare(clk
->parent
);
437 clk
->prepare_count
++;
443 * clk_prepare - prepare a clock source
444 * @clk: the clk being prepared
446 * clk_prepare may sleep, which differentiates it from clk_enable. In a simple
447 * case, clk_prepare can be used instead of clk_enable to ungate a clk if the
448 * operation may sleep. One example is a clk which is accessed over I2c. In
449 * the complex case a clk ungate operation may require a fast and a slow part.
450 * It is this reason that clk_prepare and clk_enable are not mutually
451 * exclusive. In fact clk_prepare must be called before clk_enable.
452 * Returns 0 on success, -EERROR otherwise.
454 int clk_prepare(struct clk
*clk
)
458 mutex_lock(&prepare_lock
);
459 ret
= __clk_prepare(clk
);
460 mutex_unlock(&prepare_lock
);
464 EXPORT_SYMBOL_GPL(clk_prepare
);
466 static void __clk_disable(struct clk
*clk
)
471 if (WARN_ON(clk
->enable_count
== 0))
474 if (--clk
->enable_count
> 0)
477 if (clk
->ops
->disable
)
478 clk
->ops
->disable(clk
->hw
);
480 __clk_disable(clk
->parent
);
484 * clk_disable - gate a clock
485 * @clk: the clk being gated
487 * clk_disable must not sleep, which differentiates it from clk_unprepare. In
488 * a simple case, clk_disable can be used instead of clk_unprepare to gate a
489 * clk if the operation is fast and will never sleep. One example is a
490 * SoC-internal clk which is controlled via simple register writes. In the
491 * complex case a clk gate operation may require a fast and a slow part. It is
492 * this reason that clk_unprepare and clk_disable are not mutually exclusive.
493 * In fact clk_disable must be called before clk_unprepare.
495 void clk_disable(struct clk
*clk
)
499 spin_lock_irqsave(&enable_lock
, flags
);
501 spin_unlock_irqrestore(&enable_lock
, flags
);
503 EXPORT_SYMBOL_GPL(clk_disable
);
505 static int __clk_enable(struct clk
*clk
)
512 if (WARN_ON(clk
->prepare_count
== 0))
515 if (clk
->enable_count
== 0) {
516 ret
= __clk_enable(clk
->parent
);
521 if (clk
->ops
->enable
) {
522 ret
= clk
->ops
->enable(clk
->hw
);
524 __clk_disable(clk
->parent
);
535 * clk_enable - ungate a clock
536 * @clk: the clk being ungated
538 * clk_enable must not sleep, which differentiates it from clk_prepare. In a
539 * simple case, clk_enable can be used instead of clk_prepare to ungate a clk
540 * if the operation will never sleep. One example is a SoC-internal clk which
541 * is controlled via simple register writes. In the complex case a clk ungate
542 * operation may require a fast and a slow part. It is this reason that
543 * clk_enable and clk_prepare are not mutually exclusive. In fact clk_prepare
544 * must be called before clk_enable. Returns 0 on success, -EERROR
547 int clk_enable(struct clk
*clk
)
552 spin_lock_irqsave(&enable_lock
, flags
);
553 ret
= __clk_enable(clk
);
554 spin_unlock_irqrestore(&enable_lock
, flags
);
558 EXPORT_SYMBOL_GPL(clk_enable
);
561 * clk_get_rate - return the rate of clk
562 * @clk: the clk whose rate is being returned
564 * Simply returns the cached rate of the clk. Does not query the hardware. If
565 * clk is NULL then returns -EINVAL.
567 unsigned long clk_get_rate(struct clk
*clk
)
571 mutex_lock(&prepare_lock
);
572 rate
= __clk_get_rate(clk
);
573 mutex_unlock(&prepare_lock
);
577 EXPORT_SYMBOL_GPL(clk_get_rate
);
580 * __clk_round_rate - round the given rate for a clk
581 * @clk: round the rate of this clock
583 * Caller must hold prepare_lock. Useful for clk_ops such as .set_rate
585 unsigned long __clk_round_rate(struct clk
*clk
, unsigned long rate
)
587 unsigned long unused
;
592 if (!clk
->ops
->round_rate
)
595 if (clk
->flags
& CLK_SET_RATE_PARENT
)
596 return clk
->ops
->round_rate(clk
->hw
, rate
, &unused
);
598 return clk
->ops
->round_rate(clk
->hw
, rate
, NULL
);
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
= clk
->parent
->rate
;
769 unsigned long new_rate
;
771 if (!clk
->ops
->round_rate
&& !(clk
->flags
& CLK_SET_RATE_PARENT
)) {
772 clk
->new_rate
= clk
->rate
;
776 if (!clk
->ops
->round_rate
&& (clk
->flags
& CLK_SET_RATE_PARENT
)) {
777 top
= clk_calc_new_rates(clk
->parent
, rate
);
778 new_rate
= clk
->new_rate
= clk
->parent
->new_rate
;
783 if (clk
->flags
& CLK_SET_RATE_PARENT
)
784 new_rate
= clk
->ops
->round_rate(clk
->hw
, rate
, &best_parent_rate
);
786 new_rate
= clk
->ops
->round_rate(clk
->hw
, rate
, NULL
);
788 if (best_parent_rate
!= clk
->parent
->rate
) {
789 top
= clk_calc_new_rates(clk
->parent
, best_parent_rate
);
795 clk_calc_subtree(clk
, new_rate
);
801 * Notify about rate changes in a subtree. Always walk down the whole tree
802 * so that in case of an error we can walk down the whole tree again and
805 static struct clk
*clk_propagate_rate_change(struct clk
*clk
, unsigned long event
)
807 struct hlist_node
*tmp
;
808 struct clk
*child
, *fail_clk
= NULL
;
809 int ret
= NOTIFY_DONE
;
811 if (clk
->rate
== clk
->new_rate
)
814 if (clk
->notifier_count
) {
815 ret
= __clk_notify(clk
, event
, clk
->rate
, clk
->new_rate
);
816 if (ret
== NOTIFY_BAD
)
820 hlist_for_each_entry(child
, tmp
, &clk
->children
, child_node
) {
821 clk
= clk_propagate_rate_change(child
, event
);
830 * walk down a subtree and set the new rates notifying the rate
833 static void clk_change_rate(struct clk
*clk
)
836 unsigned long old_rate
;
837 struct hlist_node
*tmp
;
839 old_rate
= clk
->rate
;
841 if (clk
->ops
->set_rate
)
842 clk
->ops
->set_rate(clk
->hw
, clk
->new_rate
);
844 if (clk
->ops
->recalc_rate
)
845 clk
->rate
= clk
->ops
->recalc_rate(clk
->hw
,
848 clk
->rate
= clk
->parent
->rate
;
850 if (clk
->notifier_count
&& old_rate
!= clk
->rate
)
851 __clk_notify(clk
, POST_RATE_CHANGE
, old_rate
, clk
->rate
);
853 hlist_for_each_entry(child
, tmp
, &clk
->children
, child_node
)
854 clk_change_rate(child
);
858 * clk_set_rate - specify a new rate for clk
859 * @clk: the clk whose rate is being changed
860 * @rate: the new rate for clk
862 * In the simplest case clk_set_rate will only change the rate of clk.
864 * If clk has the CLK_SET_RATE_GATE flag set and it is enabled this call
865 * will fail; only when the clk is disabled will it be able to change
868 * Setting the CLK_SET_RATE_PARENT flag allows clk_set_rate to
869 * recursively propagate up to clk's parent; whether or not this happens
870 * depends on the outcome of clk's .round_rate implementation. If
871 * *parent_rate is 0 after calling .round_rate then upstream parent
872 * propagation is ignored. If *parent_rate comes back with a new rate
873 * for clk's parent then we propagate up to clk's parent and set it's
874 * rate. Upward propagation will continue until either a clk does not
875 * support the CLK_SET_RATE_PARENT flag or .round_rate stops requesting
876 * changes to clk's parent_rate. If there is a failure during upstream
877 * propagation then clk_set_rate will unwind and restore each clk's rate
878 * that had been successfully changed. Afterwards a rate change abort
879 * notification will be propagated downstream, starting from the clk
882 * At the end of all of the rate setting, clk_set_rate internally calls
883 * __clk_recalc_rates and propagates the rate changes downstream,
884 * starting from the highest clk whose rate was changed. This has the
885 * added benefit of propagating post-rate change notifiers.
887 * Note that while post-rate change and rate change abort notifications
888 * are guaranteed to be sent to a clk only once per call to
889 * clk_set_rate, pre-change notifications will be sent for every clk
890 * whose rate is changed. Stacking pre-change notifications is noisy
891 * for the drivers subscribed to them, but this allows drivers to react
892 * to intermediate clk rate changes up until the point where the final
893 * rate is achieved at the end of upstream propagation.
895 * Returns 0 on success, -EERROR otherwise.
897 int clk_set_rate(struct clk
*clk
, unsigned long rate
)
899 struct clk
*top
, *fail_clk
;
902 /* prevent racing with updates to the clock topology */
903 mutex_lock(&prepare_lock
);
905 /* bail early if nothing to do */
906 if (rate
== clk
->rate
)
909 /* calculate new rates and get the topmost changed clock */
910 top
= clk_calc_new_rates(clk
, rate
);
916 /* notify that we are about to change rates */
917 fail_clk
= clk_propagate_rate_change(top
, PRE_RATE_CHANGE
);
919 pr_warn("%s: failed to set %s rate\n", __func__
,
921 clk_propagate_rate_change(top
, ABORT_RATE_CHANGE
);
926 /* change the rates */
927 clk_change_rate(top
);
929 mutex_unlock(&prepare_lock
);
933 mutex_unlock(&prepare_lock
);
937 EXPORT_SYMBOL_GPL(clk_set_rate
);
940 * clk_get_parent - return the parent of a clk
941 * @clk: the clk whose parent gets returned
943 * Simply returns clk->parent. Returns NULL if clk is NULL.
945 struct clk
*clk_get_parent(struct clk
*clk
)
949 mutex_lock(&prepare_lock
);
950 parent
= __clk_get_parent(clk
);
951 mutex_unlock(&prepare_lock
);
955 EXPORT_SYMBOL_GPL(clk_get_parent
);
958 * .get_parent is mandatory for clocks with multiple possible parents. It is
959 * optional for single-parent clocks. Always call .get_parent if it is
960 * available and WARN if it is missing for multi-parent clocks.
962 * For single-parent clocks without .get_parent, first check to see if the
963 * .parents array exists, and if so use it to avoid an expensive tree
964 * traversal. If .parents does not exist then walk the tree with __clk_lookup.
966 static struct clk
*__clk_init_parent(struct clk
*clk
)
968 struct clk
*ret
= NULL
;
971 /* handle the trivial cases */
973 if (!clk
->num_parents
)
976 if (clk
->num_parents
== 1) {
977 if (IS_ERR_OR_NULL(clk
->parent
))
978 ret
= clk
->parent
= __clk_lookup(clk
->parent_names
[0]);
983 if (!clk
->ops
->get_parent
) {
984 WARN(!clk
->ops
->get_parent
,
985 "%s: multi-parent clocks must implement .get_parent\n",
991 * Do our best to cache parent clocks in clk->parents. This prevents
992 * unnecessary and expensive calls to __clk_lookup. We don't set
993 * clk->parent here; that is done by the calling function
996 index
= clk
->ops
->get_parent(clk
->hw
);
1000 kmalloc((sizeof(struct clk
*) * clk
->num_parents
),
1004 ret
= __clk_lookup(clk
->parent_names
[index
]);
1005 else if (!clk
->parents
[index
])
1006 ret
= clk
->parents
[index
] =
1007 __clk_lookup(clk
->parent_names
[index
]);
1009 ret
= clk
->parents
[index
];
1015 void __clk_reparent(struct clk
*clk
, struct clk
*new_parent
)
1017 #ifdef CONFIG_COMMON_CLK_DEBUG
1019 struct dentry
*new_parent_d
;
1022 if (!clk
|| !new_parent
)
1025 hlist_del(&clk
->child_node
);
1028 hlist_add_head(&clk
->child_node
, &new_parent
->children
);
1030 hlist_add_head(&clk
->child_node
, &clk_orphan_list
);
1032 #ifdef CONFIG_COMMON_CLK_DEBUG
1037 new_parent_d
= new_parent
->dentry
;
1039 new_parent_d
= orphandir
;
1041 d
= debugfs_rename(clk
->dentry
->d_parent
, clk
->dentry
,
1042 new_parent_d
, clk
->name
);
1046 pr_debug("%s: failed to rename debugfs entry for %s\n",
1047 __func__
, clk
->name
);
1051 clk
->parent
= new_parent
;
1053 __clk_recalc_rates(clk
, POST_RATE_CHANGE
);
1056 static int __clk_set_parent(struct clk
*clk
, struct clk
*parent
)
1058 struct clk
*old_parent
;
1059 unsigned long flags
;
1063 old_parent
= clk
->parent
;
1065 /* find index of new parent clock using cached parent ptrs */
1066 for (i
= 0; i
< clk
->num_parents
; i
++)
1067 if (clk
->parents
[i
] == parent
)
1071 * find index of new parent clock using string name comparison
1072 * also try to cache the parent to avoid future calls to __clk_lookup
1074 if (i
== clk
->num_parents
)
1075 for (i
= 0; i
< clk
->num_parents
; i
++)
1076 if (!strcmp(clk
->parent_names
[i
], parent
->name
)) {
1077 clk
->parents
[i
] = __clk_lookup(parent
->name
);
1081 if (i
== clk
->num_parents
) {
1082 pr_debug("%s: clock %s is not a possible parent of clock %s\n",
1083 __func__
, parent
->name
, clk
->name
);
1087 /* migrate prepare and enable */
1088 if (clk
->prepare_count
)
1089 __clk_prepare(parent
);
1091 /* FIXME replace with clk_is_enabled(clk) someday */
1092 spin_lock_irqsave(&enable_lock
, flags
);
1093 if (clk
->enable_count
)
1094 __clk_enable(parent
);
1095 spin_unlock_irqrestore(&enable_lock
, flags
);
1097 /* change clock input source */
1098 ret
= clk
->ops
->set_parent(clk
->hw
, i
);
1100 /* clean up old prepare and enable */
1101 spin_lock_irqsave(&enable_lock
, flags
);
1102 if (clk
->enable_count
)
1103 __clk_disable(old_parent
);
1104 spin_unlock_irqrestore(&enable_lock
, flags
);
1106 if (clk
->prepare_count
)
1107 __clk_unprepare(old_parent
);
1114 * clk_set_parent - switch the parent of a mux clk
1115 * @clk: the mux clk whose input we are switching
1116 * @parent: the new input to clk
1118 * Re-parent clk to use parent as it's new input source. If clk has the
1119 * CLK_SET_PARENT_GATE flag set then clk must be gated for this
1120 * operation to succeed. After successfully changing clk's parent
1121 * clk_set_parent will update the clk topology, sysfs topology and
1122 * propagate rate recalculation via __clk_recalc_rates. Returns 0 on
1123 * success, -EERROR otherwise.
1125 int clk_set_parent(struct clk
*clk
, struct clk
*parent
)
1129 if (!clk
|| !clk
->ops
)
1132 if (!clk
->ops
->set_parent
)
1135 /* prevent racing with updates to the clock topology */
1136 mutex_lock(&prepare_lock
);
1138 if (clk
->parent
== parent
)
1141 /* propagate PRE_RATE_CHANGE notifications */
1142 if (clk
->notifier_count
)
1143 ret
= __clk_speculate_rates(clk
, parent
->rate
);
1145 /* abort if a driver objects */
1146 if (ret
== NOTIFY_STOP
)
1149 /* only re-parent if the clock is not in use */
1150 if ((clk
->flags
& CLK_SET_PARENT_GATE
) && clk
->prepare_count
)
1153 ret
= __clk_set_parent(clk
, parent
);
1155 /* propagate ABORT_RATE_CHANGE if .set_parent failed */
1157 __clk_recalc_rates(clk
, ABORT_RATE_CHANGE
);
1161 /* propagate rate recalculation downstream */
1162 __clk_reparent(clk
, parent
);
1165 mutex_unlock(&prepare_lock
);
1169 EXPORT_SYMBOL_GPL(clk_set_parent
);
1172 * __clk_init - initialize the data structures in a struct clk
1173 * @dev: device initializing this clk, placeholder for now
1174 * @clk: clk being initialized
1176 * Initializes the lists in struct clk, queries the hardware for the
1177 * parent and rate and sets them both.
1179 * Any struct clk passed into __clk_init must have the following members
1188 * Essentially, everything that would normally be passed into clk_register is
1189 * assumed to be initialized already in __clk_init. The other members may be
1190 * populated, but are optional.
1192 * __clk_init is only exposed via clk-private.h and is intended for use with
1193 * very large numbers of clocks that need to be statically initialized. It is
1194 * a layering violation to include clk-private.h from any code which implements
1195 * a clock's .ops; as such any statically initialized clock data MUST be in a
1196 * separate C file from the logic that implements it's operations.
1198 void __clk_init(struct device
*dev
, struct clk
*clk
)
1202 struct hlist_node
*tmp
, *tmp2
;
1207 mutex_lock(&prepare_lock
);
1209 /* check to see if a clock with this name is already registered */
1210 if (__clk_lookup(clk
->name
))
1213 /* throw a WARN if any entries in parent_names are NULL */
1214 for (i
= 0; i
< clk
->num_parents
; i
++)
1215 WARN(!clk
->parent_names
[i
],
1216 "%s: invalid NULL in %s's .parent_names\n",
1217 __func__
, clk
->name
);
1220 * Allocate an array of struct clk *'s to avoid unnecessary string
1221 * look-ups of clk's possible parents. This can fail for clocks passed
1222 * in to clk_init during early boot; thus any access to clk->parents[]
1223 * must always check for a NULL pointer and try to populate it if
1226 * If clk->parents is not NULL we skip this entire block. This allows
1227 * for clock drivers to statically initialize clk->parents.
1229 if (clk
->num_parents
&& !clk
->parents
) {
1230 clk
->parents
= kmalloc((sizeof(struct clk
*) * clk
->num_parents
),
1233 * __clk_lookup returns NULL for parents that have not been
1234 * clk_init'd; thus any access to clk->parents[] must check
1235 * for a NULL pointer. We can always perform lazy lookups for
1236 * missing parents later on.
1239 for (i
= 0; i
< clk
->num_parents
; i
++)
1241 __clk_lookup(clk
->parent_names
[i
]);
1244 clk
->parent
= __clk_init_parent(clk
);
1247 * Populate clk->parent if parent has already been __clk_init'd. If
1248 * parent has not yet been __clk_init'd then place clk in the orphan
1249 * list. If clk has set the CLK_IS_ROOT flag then place it in the root
1252 * Every time a new clk is clk_init'd then we walk the list of orphan
1253 * clocks and re-parent any that are children of the clock currently
1257 hlist_add_head(&clk
->child_node
,
1258 &clk
->parent
->children
);
1259 else if (clk
->flags
& CLK_IS_ROOT
)
1260 hlist_add_head(&clk
->child_node
, &clk_root_list
);
1262 hlist_add_head(&clk
->child_node
, &clk_orphan_list
);
1265 * Set clk's rate. The preferred method is to use .recalc_rate. For
1266 * simple clocks and lazy developers the default fallback is to use the
1267 * parent's rate. If a clock doesn't have a parent (or is orphaned)
1268 * then rate is set to zero.
1270 if (clk
->ops
->recalc_rate
)
1271 clk
->rate
= clk
->ops
->recalc_rate(clk
->hw
,
1272 __clk_get_rate(clk
->parent
));
1273 else if (clk
->parent
)
1274 clk
->rate
= clk
->parent
->rate
;
1279 * walk the list of orphan clocks and reparent any that are children of
1282 hlist_for_each_entry_safe(orphan
, tmp
, tmp2
, &clk_orphan_list
, child_node
)
1283 for (i
= 0; i
< orphan
->num_parents
; i
++)
1284 if (!strcmp(clk
->name
, orphan
->parent_names
[i
])) {
1285 __clk_reparent(orphan
, clk
);
1290 * optional platform-specific magic
1292 * The .init callback is not used by any of the basic clock types, but
1293 * exists for weird hardware that must perform initialization magic.
1294 * Please consider other ways of solving initialization problems before
1295 * using this callback, as it's use is discouraged.
1298 clk
->ops
->init(clk
->hw
);
1300 clk_debug_register(clk
);
1303 mutex_unlock(&prepare_lock
);
1309 * clk_register - allocate a new clock, register it and return an opaque cookie
1310 * @dev: device that is registering this clock
1312 * @ops: operations this clock supports
1313 * @hw: link to hardware-specific clock data
1314 * @parent_names: array of string names for all possible parents
1315 * @num_parents: number of possible parents
1316 * @flags: framework-level hints and quirks
1318 * clk_register is the primary interface for populating the clock tree with new
1319 * clock nodes. It returns a pointer to the newly allocated struct clk which
1320 * cannot be dereferenced by driver code but may be used in conjuction with the
1321 * rest of the clock API.
1323 struct clk
*clk_register(struct device
*dev
, const char *name
,
1324 const struct clk_ops
*ops
, struct clk_hw
*hw
,
1325 char **parent_names
, u8 num_parents
, unsigned long flags
)
1329 clk
= kzalloc(sizeof(*clk
), GFP_KERNEL
);
1337 clk
->parent_names
= parent_names
;
1338 clk
->num_parents
= num_parents
;
1341 __clk_init(dev
, clk
);
1345 EXPORT_SYMBOL_GPL(clk_register
);
1347 /*** clk rate change notifiers ***/
1350 * clk_notifier_register - add a clk rate change notifier
1351 * @clk: struct clk * to watch
1352 * @nb: struct notifier_block * with callback info
1354 * Request notification when clk's rate changes. This uses an SRCU
1355 * notifier because we want it to block and notifier unregistrations are
1356 * uncommon. The callbacks associated with the notifier must not
1357 * re-enter into the clk framework by calling any top-level clk APIs;
1358 * this will cause a nested prepare_lock mutex.
1360 * Pre-change notifier callbacks will be passed the current, pre-change
1361 * rate of the clk via struct clk_notifier_data.old_rate. The new,
1362 * post-change rate of the clk is passed via struct
1363 * clk_notifier_data.new_rate.
1365 * Post-change notifiers will pass the now-current, post-change rate of
1366 * the clk in both struct clk_notifier_data.old_rate and struct
1367 * clk_notifier_data.new_rate.
1369 * Abort-change notifiers are effectively the opposite of pre-change
1370 * notifiers: the original pre-change clk rate is passed in via struct
1371 * clk_notifier_data.new_rate and the failed post-change rate is passed
1372 * in via struct clk_notifier_data.old_rate.
1374 * clk_notifier_register() must be called from non-atomic context.
1375 * Returns -EINVAL if called with null arguments, -ENOMEM upon
1376 * allocation failure; otherwise, passes along the return value of
1377 * srcu_notifier_chain_register().
1379 int clk_notifier_register(struct clk
*clk
, struct notifier_block
*nb
)
1381 struct clk_notifier
*cn
;
1387 mutex_lock(&prepare_lock
);
1389 /* search the list of notifiers for this clk */
1390 list_for_each_entry(cn
, &clk_notifier_list
, node
)
1394 /* if clk wasn't in the notifier list, allocate new clk_notifier */
1395 if (cn
->clk
!= clk
) {
1396 cn
= kzalloc(sizeof(struct clk_notifier
), GFP_KERNEL
);
1401 srcu_init_notifier_head(&cn
->notifier_head
);
1403 list_add(&cn
->node
, &clk_notifier_list
);
1406 ret
= srcu_notifier_chain_register(&cn
->notifier_head
, nb
);
1408 clk
->notifier_count
++;
1411 mutex_unlock(&prepare_lock
);
1415 EXPORT_SYMBOL_GPL(clk_notifier_register
);
1418 * clk_notifier_unregister - remove a clk rate change notifier
1419 * @clk: struct clk *
1420 * @nb: struct notifier_block * with callback info
1422 * Request no further notification for changes to 'clk' and frees memory
1423 * allocated in clk_notifier_register.
1425 * Returns -EINVAL if called with null arguments; otherwise, passes
1426 * along the return value of srcu_notifier_chain_unregister().
1428 int clk_notifier_unregister(struct clk
*clk
, struct notifier_block
*nb
)
1430 struct clk_notifier
*cn
= NULL
;
1436 mutex_lock(&prepare_lock
);
1438 list_for_each_entry(cn
, &clk_notifier_list
, node
)
1442 if (cn
->clk
== clk
) {
1443 ret
= srcu_notifier_chain_unregister(&cn
->notifier_head
, nb
);
1445 clk
->notifier_count
--;
1447 /* XXX the notifier code should handle this better */
1448 if (!cn
->notifier_head
.head
) {
1449 srcu_cleanup_notifier_head(&cn
->notifier_head
);
1457 mutex_unlock(&prepare_lock
);
1461 EXPORT_SYMBOL_GPL(clk_notifier_unregister
);