Root/drivers/clk/clk.c

1/*
2 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
3 * Copyright (C) 2011-2012 Linaro Ltd <mturquette@linaro.org>
4 *
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.
8 *
9 * Standard functionality for the common clock API. See Documentation/clk.txt
10 */
11
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>
19#include <linux/of.h>
20
21static DEFINE_SPINLOCK(enable_lock);
22static DEFINE_MUTEX(prepare_lock);
23
24static HLIST_HEAD(clk_root_list);
25static HLIST_HEAD(clk_orphan_list);
26static LIST_HEAD(clk_notifier_list);
27
28/*** debugfs support ***/
29
30#ifdef CONFIG_COMMON_CLK_DEBUG
31#include <linux/debugfs.h>
32
33static struct dentry *rootdir;
34static struct dentry *orphandir;
35static int inited = 0;
36
37/* caller must hold prepare_lock */
38static int clk_debug_create_one(struct clk *clk, struct dentry *pdentry)
39{
40    struct dentry *d;
41    int ret = -ENOMEM;
42
43    if (!clk || !pdentry) {
44        ret = -EINVAL;
45        goto out;
46    }
47
48    d = debugfs_create_dir(clk->name, pdentry);
49    if (!d)
50        goto out;
51
52    clk->dentry = d;
53
54    d = debugfs_create_u32("clk_rate", S_IRUGO, clk->dentry,
55            (u32 *)&clk->rate);
56    if (!d)
57        goto err_out;
58
59    d = debugfs_create_x32("clk_flags", S_IRUGO, clk->dentry,
60            (u32 *)&clk->flags);
61    if (!d)
62        goto err_out;
63
64    d = debugfs_create_u32("clk_prepare_count", S_IRUGO, clk->dentry,
65            (u32 *)&clk->prepare_count);
66    if (!d)
67        goto err_out;
68
69    d = debugfs_create_u32("clk_enable_count", S_IRUGO, clk->dentry,
70            (u32 *)&clk->enable_count);
71    if (!d)
72        goto err_out;
73
74    d = debugfs_create_u32("clk_notifier_count", S_IRUGO, clk->dentry,
75            (u32 *)&clk->notifier_count);
76    if (!d)
77        goto err_out;
78
79    ret = 0;
80    goto out;
81
82err_out:
83    debugfs_remove(clk->dentry);
84out:
85    return ret;
86}
87
88/* caller must hold prepare_lock */
89static int clk_debug_create_subtree(struct clk *clk, struct dentry *pdentry)
90{
91    struct clk *child;
92    struct hlist_node *tmp;
93    int ret = -EINVAL;;
94
95    if (!clk || !pdentry)
96        goto out;
97
98    ret = clk_debug_create_one(clk, pdentry);
99
100    if (ret)
101        goto out;
102
103    hlist_for_each_entry(child, tmp, &clk->children, child_node)
104        clk_debug_create_subtree(child, clk->dentry);
105
106    ret = 0;
107out:
108    return ret;
109}
110
111/**
112 * clk_debug_register - add a clk node to the debugfs clk tree
113 * @clk: the clk being added to the debugfs clk tree
114 *
115 * Dynamically adds a clk to the debugfs clk tree if debugfs has been
116 * initialized. Otherwise it bails out early since the debugfs clk tree
117 * will be created lazily by clk_debug_init as part of a late_initcall.
118 *
119 * Caller must hold prepare_lock. Only clk_init calls this function (so
120 * far) so this is taken care.
121 */
122static int clk_debug_register(struct clk *clk)
123{
124    struct clk *parent;
125    struct dentry *pdentry;
126    int ret = 0;
127
128    if (!inited)
129        goto out;
130
131    parent = clk->parent;
132
133    /*
134     * Check to see if a clk is a root clk. Also check that it is
135     * safe to add this clk to debugfs
136     */
137    if (!parent)
138        if (clk->flags & CLK_IS_ROOT)
139            pdentry = rootdir;
140        else
141            pdentry = orphandir;
142    else
143        if (parent->dentry)
144            pdentry = parent->dentry;
145        else
146            goto out;
147
148    ret = clk_debug_create_subtree(clk, pdentry);
149
150out:
151    return ret;
152}
153
154/**
155 * clk_debug_init - lazily create the debugfs clk tree visualization
156 *
157 * clks are often initialized very early during boot before memory can
158 * be dynamically allocated and well before debugfs is setup.
159 * clk_debug_init walks the clk tree hierarchy while holding
160 * prepare_lock and creates the topology as part of a late_initcall,
161 * thus insuring that clks initialized very early will still be
162 * represented in the debugfs clk tree. This function should only be
163 * called once at boot-time, and all other clks added dynamically will
164 * be done so with clk_debug_register.
165 */
166static int __init clk_debug_init(void)
167{
168    struct clk *clk;
169    struct hlist_node *tmp;
170
171    rootdir = debugfs_create_dir("clk", NULL);
172
173    if (!rootdir)
174        return -ENOMEM;
175
176    orphandir = debugfs_create_dir("orphans", rootdir);
177
178    if (!orphandir)
179        return -ENOMEM;
180
181    mutex_lock(&prepare_lock);
182
183    hlist_for_each_entry(clk, tmp, &clk_root_list, child_node)
184        clk_debug_create_subtree(clk, rootdir);
185
186    hlist_for_each_entry(clk, tmp, &clk_orphan_list, child_node)
187        clk_debug_create_subtree(clk, orphandir);
188
189    inited = 1;
190
191    mutex_unlock(&prepare_lock);
192
193    return 0;
194}
195late_initcall(clk_debug_init);
196#else
197static inline int clk_debug_register(struct clk *clk) { return 0; }
198#endif
199
200/* caller must hold prepare_lock */
201static void clk_disable_unused_subtree(struct clk *clk)
202{
203    struct clk *child;
204    struct hlist_node *tmp;
205    unsigned long flags;
206
207    if (!clk)
208        goto out;
209
210    hlist_for_each_entry(child, tmp, &clk->children, child_node)
211        clk_disable_unused_subtree(child);
212
213    spin_lock_irqsave(&enable_lock, flags);
214
215    if (clk->enable_count)
216        goto unlock_out;
217
218    if (clk->flags & CLK_IGNORE_UNUSED)
219        goto unlock_out;
220
221    if (__clk_is_enabled(clk) && clk->ops->disable)
222        clk->ops->disable(clk->hw);
223
224unlock_out:
225    spin_unlock_irqrestore(&enable_lock, flags);
226
227out:
228    return;
229}
230
231static int clk_disable_unused(void)
232{
233    struct clk *clk;
234    struct hlist_node *tmp;
235
236    mutex_lock(&prepare_lock);
237
238    hlist_for_each_entry(clk, tmp, &clk_root_list, child_node)
239        clk_disable_unused_subtree(clk);
240
241    hlist_for_each_entry(clk, tmp, &clk_orphan_list, child_node)
242        clk_disable_unused_subtree(clk);
243
244    mutex_unlock(&prepare_lock);
245
246    return 0;
247}
248late_initcall(clk_disable_unused);
249
250/*** helper functions ***/
251
252inline const char *__clk_get_name(struct clk *clk)
253{
254    return !clk ? NULL : clk->name;
255}
256
257inline struct clk_hw *__clk_get_hw(struct clk *clk)
258{
259    return !clk ? NULL : clk->hw;
260}
261
262inline u8 __clk_get_num_parents(struct clk *clk)
263{
264    return !clk ? -EINVAL : clk->num_parents;
265}
266
267inline struct clk *__clk_get_parent(struct clk *clk)
268{
269    return !clk ? NULL : clk->parent;
270}
271
272inline int __clk_get_enable_count(struct clk *clk)
273{
274    return !clk ? -EINVAL : clk->enable_count;
275}
276
277inline int __clk_get_prepare_count(struct clk *clk)
278{
279    return !clk ? -EINVAL : clk->prepare_count;
280}
281
282unsigned long __clk_get_rate(struct clk *clk)
283{
284    unsigned long ret;
285
286    if (!clk) {
287        ret = 0;
288        goto out;
289    }
290
291    ret = clk->rate;
292
293    if (clk->flags & CLK_IS_ROOT)
294        goto out;
295
296    if (!clk->parent)
297        ret = 0;
298
299out:
300    return ret;
301}
302
303inline unsigned long __clk_get_flags(struct clk *clk)
304{
305    return !clk ? -EINVAL : clk->flags;
306}
307
308int __clk_is_enabled(struct clk *clk)
309{
310    int ret;
311
312    if (!clk)
313        return -EINVAL;
314
315    /*
316     * .is_enabled is only mandatory for clocks that gate
317     * fall back to software usage counter if .is_enabled is missing
318     */
319    if (!clk->ops->is_enabled) {
320        ret = clk->enable_count ? 1 : 0;
321        goto out;
322    }
323
324    ret = clk->ops->is_enabled(clk->hw);
325out:
326    return ret;
327}
328
329static struct clk *__clk_lookup_subtree(const char *name, struct clk *clk)
330{
331    struct clk *child;
332    struct clk *ret;
333    struct hlist_node *tmp;
334
335    if (!strcmp(clk->name, name))
336        return clk;
337
338    hlist_for_each_entry(child, tmp, &clk->children, child_node) {
339        ret = __clk_lookup_subtree(name, child);
340        if (ret)
341            return ret;
342    }
343
344    return NULL;
345}
346
347struct clk *__clk_lookup(const char *name)
348{
349    struct clk *root_clk;
350    struct clk *ret;
351    struct hlist_node *tmp;
352
353    if (!name)
354        return NULL;
355
356    /* search the 'proper' clk tree first */
357    hlist_for_each_entry(root_clk, tmp, &clk_root_list, child_node) {
358        ret = __clk_lookup_subtree(name, root_clk);
359        if (ret)
360            return ret;
361    }
362
363    /* if not found, then search the orphan tree */
364    hlist_for_each_entry(root_clk, tmp, &clk_orphan_list, child_node) {
365        ret = __clk_lookup_subtree(name, root_clk);
366        if (ret)
367            return ret;
368    }
369
370    return NULL;
371}
372
373/*** clk api ***/
374
375void __clk_unprepare(struct clk *clk)
376{
377    if (!clk)
378        return;
379
380    if (WARN_ON(clk->prepare_count == 0))
381        return;
382
383    if (--clk->prepare_count > 0)
384        return;
385
386    WARN_ON(clk->enable_count > 0);
387
388    if (clk->ops->unprepare)
389        clk->ops->unprepare(clk->hw);
390
391    __clk_unprepare(clk->parent);
392}
393
394/**
395 * clk_unprepare - undo preparation of a clock source
396 * @clk: the clk being unprepare
397 *
398 * clk_unprepare may sleep, which differentiates it from clk_disable. In a
399 * simple case, clk_unprepare can be used instead of clk_disable to gate a clk
400 * if the operation may sleep. One example is a clk which is accessed over
401 * I2c. In the complex case a clk gate operation may require a fast and a slow
402 * part. It is this reason that clk_unprepare and clk_disable are not mutually
403 * exclusive. In fact clk_disable must be called before clk_unprepare.
404 */
405void clk_unprepare(struct clk *clk)
406{
407    mutex_lock(&prepare_lock);
408    __clk_unprepare(clk);
409    mutex_unlock(&prepare_lock);
410}
411EXPORT_SYMBOL_GPL(clk_unprepare);
412
413int __clk_prepare(struct clk *clk)
414{
415    int ret = 0;
416
417    if (!clk)
418        return 0;
419
420    if (clk->prepare_count == 0) {
421        ret = __clk_prepare(clk->parent);
422        if (ret)
423            return ret;
424
425        if (clk->ops->prepare) {
426            ret = clk->ops->prepare(clk->hw);
427            if (ret) {
428                __clk_unprepare(clk->parent);
429                return ret;
430            }
431        }
432    }
433
434    clk->prepare_count++;
435
436    return 0;
437}
438
439/**
440 * clk_prepare - prepare a clock source
441 * @clk: the clk being prepared
442 *
443 * clk_prepare may sleep, which differentiates it from clk_enable. In a simple
444 * case, clk_prepare can be used instead of clk_enable to ungate a clk if the
445 * operation may sleep. One example is a clk which is accessed over I2c. In
446 * the complex case a clk ungate operation may require a fast and a slow part.
447 * It is this reason that clk_prepare and clk_enable are not mutually
448 * exclusive. In fact clk_prepare must be called before clk_enable.
449 * Returns 0 on success, -EERROR otherwise.
450 */
451int clk_prepare(struct clk *clk)
452{
453    int ret;
454
455    mutex_lock(&prepare_lock);
456    ret = __clk_prepare(clk);
457    mutex_unlock(&prepare_lock);
458
459    return ret;
460}
461EXPORT_SYMBOL_GPL(clk_prepare);
462
463static void __clk_disable(struct clk *clk)
464{
465    if (!clk)
466        return;
467
468    if (WARN_ON(IS_ERR(clk)))
469        return;
470
471    if (WARN_ON(clk->enable_count == 0))
472        return;
473
474    if (--clk->enable_count > 0)
475        return;
476
477    if (clk->ops->disable)
478        clk->ops->disable(clk->hw);
479
480    __clk_disable(clk->parent);
481}
482
483/**
484 * clk_disable - gate a clock
485 * @clk: the clk being gated
486 *
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.
494 */
495void clk_disable(struct clk *clk)
496{
497    unsigned long flags;
498
499    spin_lock_irqsave(&enable_lock, flags);
500    __clk_disable(clk);
501    spin_unlock_irqrestore(&enable_lock, flags);
502}
503EXPORT_SYMBOL_GPL(clk_disable);
504
505static int __clk_enable(struct clk *clk)
506{
507    int ret = 0;
508
509    if (!clk)
510        return 0;
511
512    if (WARN_ON(clk->prepare_count == 0))
513        return -ESHUTDOWN;
514
515    if (clk->enable_count == 0) {
516        ret = __clk_enable(clk->parent);
517
518        if (ret)
519            return ret;
520
521        if (clk->ops->enable) {
522            ret = clk->ops->enable(clk->hw);
523            if (ret) {
524                __clk_disable(clk->parent);
525                return ret;
526            }
527        }
528    }
529
530    clk->enable_count++;
531    return 0;
532}
533
534/**
535 * clk_enable - ungate a clock
536 * @clk: the clk being ungated
537 *
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
545 * otherwise.
546 */
547int clk_enable(struct clk *clk)
548{
549    unsigned long flags;
550    int ret;
551
552    spin_lock_irqsave(&enable_lock, flags);
553    ret = __clk_enable(clk);
554    spin_unlock_irqrestore(&enable_lock, flags);
555
556    return ret;
557}
558EXPORT_SYMBOL_GPL(clk_enable);
559
560/**
561 * clk_get_rate - return the rate of clk
562 * @clk: the clk whose rate is being returned
563 *
564 * Simply returns the cached rate of the clk. Does not query the hardware. If
565 * clk is NULL then returns 0.
566 */
567unsigned long clk_get_rate(struct clk *clk)
568{
569    unsigned long rate;
570
571    mutex_lock(&prepare_lock);
572    rate = __clk_get_rate(clk);
573    mutex_unlock(&prepare_lock);
574
575    return rate;
576}
577EXPORT_SYMBOL_GPL(clk_get_rate);
578
579/**
580 * __clk_round_rate - round the given rate for a clk
581 * @clk: round the rate of this clock
582 *
583 * Caller must hold prepare_lock. Useful for clk_ops such as .set_rate
584 */
585unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
586{
587    unsigned long parent_rate = 0;
588
589    if (!clk)
590        return -EINVAL;
591
592    if (!clk->ops->round_rate) {
593        if (clk->flags & CLK_SET_RATE_PARENT)
594            return __clk_round_rate(clk->parent, rate);
595        else
596            return clk->rate;
597    }
598
599    if (clk->parent)
600        parent_rate = clk->parent->rate;
601
602    return clk->ops->round_rate(clk->hw, rate, &parent_rate);
603}
604
605/**
606 * clk_round_rate - round the given rate for a clk
607 * @clk: the clk for which we are rounding a rate
608 * @rate: the rate which is to be rounded
609 *
610 * Takes in a rate as input and rounds it to a rate that the clk can actually
611 * use which is then returned. If clk doesn't support round_rate operation
612 * then the parent rate is returned.
613 */
614long clk_round_rate(struct clk *clk, unsigned long rate)
615{
616    unsigned long ret;
617
618    mutex_lock(&prepare_lock);
619    ret = __clk_round_rate(clk, rate);
620    mutex_unlock(&prepare_lock);
621
622    return ret;
623}
624EXPORT_SYMBOL_GPL(clk_round_rate);
625
626/**
627 * __clk_notify - call clk notifier chain
628 * @clk: struct clk * that is changing rate
629 * @msg: clk notifier type (see include/linux/clk.h)
630 * @old_rate: old clk rate
631 * @new_rate: new clk rate
632 *
633 * Triggers a notifier call chain on the clk rate-change notification
634 * for 'clk'. Passes a pointer to the struct clk and the previous
635 * and current rates to the notifier callback. Intended to be called by
636 * internal clock code only. Returns NOTIFY_DONE from the last driver
637 * called if all went well, or NOTIFY_STOP or NOTIFY_BAD immediately if
638 * a driver returns that.
639 */
640static int __clk_notify(struct clk *clk, unsigned long msg,
641        unsigned long old_rate, unsigned long new_rate)
642{
643    struct clk_notifier *cn;
644    struct clk_notifier_data cnd;
645    int ret = NOTIFY_DONE;
646
647    cnd.clk = clk;
648    cnd.old_rate = old_rate;
649    cnd.new_rate = new_rate;
650
651    list_for_each_entry(cn, &clk_notifier_list, node) {
652        if (cn->clk == clk) {
653            ret = srcu_notifier_call_chain(&cn->notifier_head, msg,
654                    &cnd);
655            break;
656        }
657    }
658
659    return ret;
660}
661
662/**
663 * __clk_recalc_rates
664 * @clk: first clk in the subtree
665 * @msg: notification type (see include/linux/clk.h)
666 *
667 * Walks the subtree of clks starting with clk and recalculates rates as it
668 * goes. Note that if a clk does not implement the .recalc_rate callback then
669 * it is assumed that the clock will take on the rate of it's parent.
670 *
671 * clk_recalc_rates also propagates the POST_RATE_CHANGE notification,
672 * if necessary.
673 *
674 * Caller must hold prepare_lock.
675 */
676static void __clk_recalc_rates(struct clk *clk, unsigned long msg)
677{
678    unsigned long old_rate;
679    unsigned long parent_rate = 0;
680    struct hlist_node *tmp;
681    struct clk *child;
682
683    old_rate = clk->rate;
684
685    if (clk->parent)
686        parent_rate = clk->parent->rate;
687
688    if (clk->ops->recalc_rate)
689        clk->rate = clk->ops->recalc_rate(clk->hw, parent_rate);
690    else
691        clk->rate = parent_rate;
692
693    /*
694     * ignore NOTIFY_STOP and NOTIFY_BAD return values for POST_RATE_CHANGE
695     * & ABORT_RATE_CHANGE notifiers
696     */
697    if (clk->notifier_count && msg)
698        __clk_notify(clk, msg, old_rate, clk->rate);
699
700    hlist_for_each_entry(child, tmp, &clk->children, child_node)
701        __clk_recalc_rates(child, msg);
702}
703
704/**
705 * __clk_speculate_rates
706 * @clk: first clk in the subtree
707 * @parent_rate: the "future" rate of clk's parent
708 *
709 * Walks the subtree of clks starting with clk, speculating rates as it
710 * goes and firing off PRE_RATE_CHANGE notifications as necessary.
711 *
712 * Unlike clk_recalc_rates, clk_speculate_rates exists only for sending
713 * pre-rate change notifications and returns early if no clks in the
714 * subtree have subscribed to the notifications. Note that if a clk does not
715 * implement the .recalc_rate callback then it is assumed that the clock will
716 * take on the rate of it's parent.
717 *
718 * Caller must hold prepare_lock.
719 */
720static int __clk_speculate_rates(struct clk *clk, unsigned long parent_rate)
721{
722    struct hlist_node *tmp;
723    struct clk *child;
724    unsigned long new_rate;
725    int ret = NOTIFY_DONE;
726
727    if (clk->ops->recalc_rate)
728        new_rate = clk->ops->recalc_rate(clk->hw, parent_rate);
729    else
730        new_rate = parent_rate;
731
732    /* abort the rate change if a driver returns NOTIFY_BAD */
733    if (clk->notifier_count)
734        ret = __clk_notify(clk, PRE_RATE_CHANGE, clk->rate, new_rate);
735
736    if (ret == NOTIFY_BAD)
737        goto out;
738
739    hlist_for_each_entry(child, tmp, &clk->children, child_node) {
740        ret = __clk_speculate_rates(child, new_rate);
741        if (ret == NOTIFY_BAD)
742            break;
743    }
744
745out:
746    return ret;
747}
748
749static void clk_calc_subtree(struct clk *clk, unsigned long new_rate)
750{
751    struct clk *child;
752    struct hlist_node *tmp;
753
754    clk->new_rate = new_rate;
755
756    hlist_for_each_entry(child, tmp, &clk->children, child_node) {
757        if (child->ops->recalc_rate)
758            child->new_rate = child->ops->recalc_rate(child->hw, new_rate);
759        else
760            child->new_rate = new_rate;
761        clk_calc_subtree(child, child->new_rate);
762    }
763}
764
765/*
766 * calculate the new rates returning the topmost clock that has to be
767 * changed.
768 */
769static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)
770{
771    struct clk *top = clk;
772    unsigned long best_parent_rate = 0;
773    unsigned long new_rate;
774
775    /* sanity */
776    if (IS_ERR_OR_NULL(clk))
777        return NULL;
778
779    /* save parent rate, if it exists */
780    if (clk->parent)
781        best_parent_rate = clk->parent->rate;
782
783    /* never propagate up to the parent */
784    if (!(clk->flags & CLK_SET_RATE_PARENT)) {
785        if (!clk->ops->round_rate) {
786            clk->new_rate = clk->rate;
787            return NULL;
788        }
789        new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
790        goto out;
791    }
792
793    /* need clk->parent from here on out */
794    if (!clk->parent) {
795        pr_debug("%s: %s has NULL parent\n", __func__, clk->name);
796        return NULL;
797    }
798
799    if (!clk->ops->round_rate) {
800        top = clk_calc_new_rates(clk->parent, rate);
801        new_rate = clk->parent->new_rate;
802
803        goto out;
804    }
805
806    new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
807
808    if (best_parent_rate != clk->parent->rate) {
809        top = clk_calc_new_rates(clk->parent, best_parent_rate);
810
811        goto out;
812    }
813
814out:
815    clk_calc_subtree(clk, new_rate);
816
817    return top;
818}
819
820/*
821 * Notify about rate changes in a subtree. Always walk down the whole tree
822 * so that in case of an error we can walk down the whole tree again and
823 * abort the change.
824 */
825static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long event)
826{
827    struct hlist_node *tmp;
828    struct clk *child, *fail_clk = NULL;
829    int ret = NOTIFY_DONE;
830
831    if (clk->rate == clk->new_rate)
832        return 0;
833
834    if (clk->notifier_count) {
835        ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
836        if (ret == NOTIFY_BAD)
837            fail_clk = clk;
838    }
839
840    hlist_for_each_entry(child, tmp, &clk->children, child_node) {
841        clk = clk_propagate_rate_change(child, event);
842        if (clk)
843            fail_clk = clk;
844    }
845
846    return fail_clk;
847}
848
849/*
850 * walk down a subtree and set the new rates notifying the rate
851 * change on the way
852 */
853static void clk_change_rate(struct clk *clk)
854{
855    struct clk *child;
856    unsigned long old_rate;
857    unsigned long best_parent_rate = 0;
858    struct hlist_node *tmp;
859
860    old_rate = clk->rate;
861
862    if (clk->parent)
863        best_parent_rate = clk->parent->rate;
864
865    if (clk->ops->set_rate)
866        clk->ops->set_rate(clk->hw, clk->new_rate, best_parent_rate);
867
868    if (clk->ops->recalc_rate)
869        clk->rate = clk->ops->recalc_rate(clk->hw, best_parent_rate);
870    else
871        clk->rate = best_parent_rate;
872
873    if (clk->notifier_count && old_rate != clk->rate)
874        __clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate);
875
876    hlist_for_each_entry(child, tmp, &clk->children, child_node)
877        clk_change_rate(child);
878}
879
880/**
881 * clk_set_rate - specify a new rate for clk
882 * @clk: the clk whose rate is being changed
883 * @rate: the new rate for clk
884 *
885 * In the simplest case clk_set_rate will only adjust the rate of clk.
886 *
887 * Setting the CLK_SET_RATE_PARENT flag allows the rate change operation to
888 * propagate up to clk's parent; whether or not this happens depends on the
889 * outcome of clk's .round_rate implementation. If *parent_rate is unchanged
890 * after calling .round_rate then upstream parent propagation is ignored. If
891 * *parent_rate comes back with a new rate for clk's parent then we propagate
892 * up to clk's parent and set it's rate. Upward propagation will continue
893 * until either a clk does not support the CLK_SET_RATE_PARENT flag or
894 * .round_rate stops requesting changes to clk's parent_rate.
895 *
896 * Rate changes are accomplished via tree traversal that also recalculates the
897 * rates for the clocks and fires off POST_RATE_CHANGE notifiers.
898 *
899 * Returns 0 on success, -EERROR otherwise.
900 */
901int clk_set_rate(struct clk *clk, unsigned long rate)
902{
903    struct clk *top, *fail_clk;
904    int ret = 0;
905
906    /* prevent racing with updates to the clock topology */
907    mutex_lock(&prepare_lock);
908
909    /* bail early if nothing to do */
910    if (rate == clk->rate)
911        goto out;
912
913    if ((clk->flags & CLK_SET_RATE_GATE) && clk->prepare_count) {
914        ret = -EBUSY;
915        goto out;
916    }
917
918    /* calculate new rates and get the topmost changed clock */
919    top = clk_calc_new_rates(clk, rate);
920    if (!top) {
921        ret = -EINVAL;
922        goto out;
923    }
924
925    /* notify that we are about to change rates */
926    fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE);
927    if (fail_clk) {
928        pr_warn("%s: failed to set %s rate\n", __func__,
929                fail_clk->name);
930        clk_propagate_rate_change(top, ABORT_RATE_CHANGE);
931        ret = -EBUSY;
932        goto out;
933    }
934
935    /* change the rates */
936    clk_change_rate(top);
937
938    mutex_unlock(&prepare_lock);
939
940    return 0;
941out:
942    mutex_unlock(&prepare_lock);
943
944    return ret;
945}
946EXPORT_SYMBOL_GPL(clk_set_rate);
947
948/**
949 * clk_get_parent - return the parent of a clk
950 * @clk: the clk whose parent gets returned
951 *
952 * Simply returns clk->parent. Returns NULL if clk is NULL.
953 */
954struct clk *clk_get_parent(struct clk *clk)
955{
956    struct clk *parent;
957
958    mutex_lock(&prepare_lock);
959    parent = __clk_get_parent(clk);
960    mutex_unlock(&prepare_lock);
961
962    return parent;
963}
964EXPORT_SYMBOL_GPL(clk_get_parent);
965
966/*
967 * .get_parent is mandatory for clocks with multiple possible parents. It is
968 * optional for single-parent clocks. Always call .get_parent if it is
969 * available and WARN if it is missing for multi-parent clocks.
970 *
971 * For single-parent clocks without .get_parent, first check to see if the
972 * .parents array exists, and if so use it to avoid an expensive tree
973 * traversal. If .parents does not exist then walk the tree with __clk_lookup.
974 */
975static struct clk *__clk_init_parent(struct clk *clk)
976{
977    struct clk *ret = NULL;
978    u8 index;
979
980    /* handle the trivial cases */
981
982    if (!clk->num_parents)
983        goto out;
984
985    if (clk->num_parents == 1) {
986        if (IS_ERR_OR_NULL(clk->parent))
987            ret = clk->parent = __clk_lookup(clk->parent_names[0]);
988        ret = clk->parent;
989        goto out;
990    }
991
992    if (!clk->ops->get_parent) {
993        WARN(!clk->ops->get_parent,
994            "%s: multi-parent clocks must implement .get_parent\n",
995            __func__);
996        goto out;
997    };
998
999    /*
1000     * Do our best to cache parent clocks in clk->parents. This prevents
1001     * unnecessary and expensive calls to __clk_lookup. We don't set
1002     * clk->parent here; that is done by the calling function
1003     */
1004
1005    index = clk->ops->get_parent(clk->hw);
1006
1007    if (!clk->parents)
1008        clk->parents =
1009            kzalloc((sizeof(struct clk*) * clk->num_parents),
1010                    GFP_KERNEL);
1011
1012    if (!clk->parents)
1013        ret = __clk_lookup(clk->parent_names[index]);
1014    else if (!clk->parents[index])
1015        ret = clk->parents[index] =
1016            __clk_lookup(clk->parent_names[index]);
1017    else
1018        ret = clk->parents[index];
1019
1020out:
1021    return ret;
1022}
1023
1024void __clk_reparent(struct clk *clk, struct clk *new_parent)
1025{
1026#ifdef CONFIG_COMMON_CLK_DEBUG
1027    struct dentry *d;
1028    struct dentry *new_parent_d;
1029#endif
1030
1031    if (!clk || !new_parent)
1032        return;
1033
1034    hlist_del(&clk->child_node);
1035
1036    if (new_parent)
1037        hlist_add_head(&clk->child_node, &new_parent->children);
1038    else
1039        hlist_add_head(&clk->child_node, &clk_orphan_list);
1040
1041#ifdef CONFIG_COMMON_CLK_DEBUG
1042    if (!inited)
1043        goto out;
1044
1045    if (new_parent)
1046        new_parent_d = new_parent->dentry;
1047    else
1048        new_parent_d = orphandir;
1049
1050    d = debugfs_rename(clk->dentry->d_parent, clk->dentry,
1051            new_parent_d, clk->name);
1052    if (d)
1053        clk->dentry = d;
1054    else
1055        pr_debug("%s: failed to rename debugfs entry for %s\n",
1056                __func__, clk->name);
1057out:
1058#endif
1059
1060    clk->parent = new_parent;
1061
1062    __clk_recalc_rates(clk, POST_RATE_CHANGE);
1063}
1064
1065static int __clk_set_parent(struct clk *clk, struct clk *parent)
1066{
1067    struct clk *old_parent;
1068    unsigned long flags;
1069    int ret = -EINVAL;
1070    u8 i;
1071
1072    old_parent = clk->parent;
1073
1074    if (!clk->parents)
1075        clk->parents = kzalloc((sizeof(struct clk*) * clk->num_parents),
1076                                GFP_KERNEL);
1077
1078    /*
1079     * find index of new parent clock using cached parent ptrs,
1080     * or if not yet cached, use string name comparison and cache
1081     * them now to avoid future calls to __clk_lookup.
1082     */
1083    for (i = 0; i < clk->num_parents; i++) {
1084        if (clk->parents && clk->parents[i] == parent)
1085            break;
1086        else if (!strcmp(clk->parent_names[i], parent->name)) {
1087            if (clk->parents)
1088                clk->parents[i] = __clk_lookup(parent->name);
1089            break;
1090        }
1091    }
1092
1093    if (i == clk->num_parents) {
1094        pr_debug("%s: clock %s is not a possible parent of clock %s\n",
1095                __func__, parent->name, clk->name);
1096        goto out;
1097    }
1098
1099    /* migrate prepare and enable */
1100    if (clk->prepare_count)
1101        __clk_prepare(parent);
1102
1103    /* FIXME replace with clk_is_enabled(clk) someday */
1104    spin_lock_irqsave(&enable_lock, flags);
1105    if (clk->enable_count)
1106        __clk_enable(parent);
1107    spin_unlock_irqrestore(&enable_lock, flags);
1108
1109    /* change clock input source */
1110    ret = clk->ops->set_parent(clk->hw, i);
1111
1112    /* clean up old prepare and enable */
1113    spin_lock_irqsave(&enable_lock, flags);
1114    if (clk->enable_count)
1115        __clk_disable(old_parent);
1116    spin_unlock_irqrestore(&enable_lock, flags);
1117
1118    if (clk->prepare_count)
1119        __clk_unprepare(old_parent);
1120
1121out:
1122    return ret;
1123}
1124
1125/**
1126 * clk_set_parent - switch the parent of a mux clk
1127 * @clk: the mux clk whose input we are switching
1128 * @parent: the new input to clk
1129 *
1130 * Re-parent clk to use parent as it's new input source. If clk has the
1131 * CLK_SET_PARENT_GATE flag set then clk must be gated for this
1132 * operation to succeed. After successfully changing clk's parent
1133 * clk_set_parent will update the clk topology, sysfs topology and
1134 * propagate rate recalculation via __clk_recalc_rates. Returns 0 on
1135 * success, -EERROR otherwise.
1136 */
1137int clk_set_parent(struct clk *clk, struct clk *parent)
1138{
1139    int ret = 0;
1140
1141    if (!clk || !clk->ops)
1142        return -EINVAL;
1143
1144    if (!clk->ops->set_parent)
1145        return -ENOSYS;
1146
1147    /* prevent racing with updates to the clock topology */
1148    mutex_lock(&prepare_lock);
1149
1150    if (clk->parent == parent)
1151        goto out;
1152
1153    /* propagate PRE_RATE_CHANGE notifications */
1154    if (clk->notifier_count)
1155        ret = __clk_speculate_rates(clk, parent->rate);
1156
1157    /* abort if a driver objects */
1158    if (ret == NOTIFY_STOP)
1159        goto out;
1160
1161    /* only re-parent if the clock is not in use */
1162    if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count)
1163        ret = -EBUSY;
1164    else
1165        ret = __clk_set_parent(clk, parent);
1166
1167    /* propagate ABORT_RATE_CHANGE if .set_parent failed */
1168    if (ret) {
1169        __clk_recalc_rates(clk, ABORT_RATE_CHANGE);
1170        goto out;
1171    }
1172
1173    /* propagate rate recalculation downstream */
1174    __clk_reparent(clk, parent);
1175
1176out:
1177    mutex_unlock(&prepare_lock);
1178
1179    return ret;
1180}
1181EXPORT_SYMBOL_GPL(clk_set_parent);
1182
1183/**
1184 * __clk_init - initialize the data structures in a struct clk
1185 * @dev: device initializing this clk, placeholder for now
1186 * @clk: clk being initialized
1187 *
1188 * Initializes the lists in struct clk, queries the hardware for the
1189 * parent and rate and sets them both.
1190 */
1191int __clk_init(struct device *dev, struct clk *clk)
1192{
1193    int i, ret = 0;
1194    struct clk *orphan;
1195    struct hlist_node *tmp, *tmp2;
1196
1197    if (!clk)
1198        return -EINVAL;
1199
1200    mutex_lock(&prepare_lock);
1201
1202    /* check to see if a clock with this name is already registered */
1203    if (__clk_lookup(clk->name)) {
1204        pr_debug("%s: clk %s already initialized\n",
1205                __func__, clk->name);
1206        ret = -EEXIST;
1207        goto out;
1208    }
1209
1210    /* check that clk_ops are sane. See Documentation/clk.txt */
1211    if (clk->ops->set_rate &&
1212            !(clk->ops->round_rate && clk->ops->recalc_rate)) {
1213        pr_warning("%s: %s must implement .round_rate & .recalc_rate\n",
1214                __func__, clk->name);
1215        ret = -EINVAL;
1216        goto out;
1217    }
1218
1219    if (clk->ops->set_parent && !clk->ops->get_parent) {
1220        pr_warning("%s: %s must implement .get_parent & .set_parent\n",
1221                __func__, clk->name);
1222        ret = -EINVAL;
1223        goto out;
1224    }
1225
1226    /* throw a WARN if any entries in parent_names are NULL */
1227    for (i = 0; i < clk->num_parents; i++)
1228        WARN(!clk->parent_names[i],
1229                "%s: invalid NULL in %s's .parent_names\n",
1230                __func__, clk->name);
1231
1232    /*
1233     * Allocate an array of struct clk *'s to avoid unnecessary string
1234     * look-ups of clk's possible parents. This can fail for clocks passed
1235     * in to clk_init during early boot; thus any access to clk->parents[]
1236     * must always check for a NULL pointer and try to populate it if
1237     * necessary.
1238     *
1239     * If clk->parents is not NULL we skip this entire block. This allows
1240     * for clock drivers to statically initialize clk->parents.
1241     */
1242    if (clk->num_parents > 1 && !clk->parents) {
1243        clk->parents = kzalloc((sizeof(struct clk*) * clk->num_parents),
1244                GFP_KERNEL);
1245        /*
1246         * __clk_lookup returns NULL for parents that have not been
1247         * clk_init'd; thus any access to clk->parents[] must check
1248         * for a NULL pointer. We can always perform lazy lookups for
1249         * missing parents later on.
1250         */
1251        if (clk->parents)
1252            for (i = 0; i < clk->num_parents; i++)
1253                clk->parents[i] =
1254                    __clk_lookup(clk->parent_names[i]);
1255    }
1256
1257    clk->parent = __clk_init_parent(clk);
1258
1259    /*
1260     * Populate clk->parent if parent has already been __clk_init'd. If
1261     * parent has not yet been __clk_init'd then place clk in the orphan
1262     * list. If clk has set the CLK_IS_ROOT flag then place it in the root
1263     * clk list.
1264     *
1265     * Every time a new clk is clk_init'd then we walk the list of orphan
1266     * clocks and re-parent any that are children of the clock currently
1267     * being clk_init'd.
1268     */
1269    if (clk->parent)
1270        hlist_add_head(&clk->child_node,
1271                &clk->parent->children);
1272    else if (clk->flags & CLK_IS_ROOT)
1273        hlist_add_head(&clk->child_node, &clk_root_list);
1274    else
1275        hlist_add_head(&clk->child_node, &clk_orphan_list);
1276
1277    /*
1278     * Set clk's rate. The preferred method is to use .recalc_rate. For
1279     * simple clocks and lazy developers the default fallback is to use the
1280     * parent's rate. If a clock doesn't have a parent (or is orphaned)
1281     * then rate is set to zero.
1282     */
1283    if (clk->ops->recalc_rate)
1284        clk->rate = clk->ops->recalc_rate(clk->hw,
1285                __clk_get_rate(clk->parent));
1286    else if (clk->parent)
1287        clk->rate = clk->parent->rate;
1288    else
1289        clk->rate = 0;
1290
1291    /*
1292     * walk the list of orphan clocks and reparent any that are children of
1293     * this clock
1294     */
1295    hlist_for_each_entry_safe(orphan, tmp, tmp2, &clk_orphan_list, child_node)
1296        for (i = 0; i < orphan->num_parents; i++)
1297            if (!strcmp(clk->name, orphan->parent_names[i])) {
1298                __clk_reparent(orphan, clk);
1299                break;
1300            }
1301
1302    /*
1303     * optional platform-specific magic
1304     *
1305     * The .init callback is not used by any of the basic clock types, but
1306     * exists for weird hardware that must perform initialization magic.
1307     * Please consider other ways of solving initialization problems before
1308     * using this callback, as it's use is discouraged.
1309     */
1310    if (clk->ops->init)
1311        clk->ops->init(clk->hw);
1312
1313    clk_debug_register(clk);
1314
1315out:
1316    mutex_unlock(&prepare_lock);
1317
1318    return ret;
1319}
1320
1321/**
1322 * __clk_register - register a clock and return a cookie.
1323 *
1324 * Same as clk_register, except that the .clk field inside hw shall point to a
1325 * preallocated (generally statically allocated) struct clk. None of the fields
1326 * of the struct clk need to be initialized.
1327 *
1328 * The data pointed to by .init and .clk field shall NOT be marked as init
1329 * data.
1330 *
1331 * __clk_register is only exposed via clk-private.h and is intended for use with
1332 * very large numbers of clocks that need to be statically initialized. It is
1333 * a layering violation to include clk-private.h from any code which implements
1334 * a clock's .ops; as such any statically initialized clock data MUST be in a
1335 * separate C file from the logic that implements it's operations. Returns 0
1336 * on success, otherwise an error code.
1337 */
1338struct clk *__clk_register(struct device *dev, struct clk_hw *hw)
1339{
1340    int ret;
1341    struct clk *clk;
1342
1343    clk = hw->clk;
1344    clk->name = hw->init->name;
1345    clk->ops = hw->init->ops;
1346    clk->hw = hw;
1347    clk->flags = hw->init->flags;
1348    clk->parent_names = hw->init->parent_names;
1349    clk->num_parents = hw->init->num_parents;
1350
1351    ret = __clk_init(dev, clk);
1352    if (ret)
1353        return ERR_PTR(ret);
1354
1355    return clk;
1356}
1357EXPORT_SYMBOL_GPL(__clk_register);
1358
1359/**
1360 * clk_register - allocate a new clock, register it and return an opaque cookie
1361 * @dev: device that is registering this clock
1362 * @hw: link to hardware-specific clock data
1363 *
1364 * clk_register is the primary interface for populating the clock tree with new
1365 * clock nodes. It returns a pointer to the newly allocated struct clk which
1366 * cannot be dereferenced by driver code but may be used in conjuction with the
1367 * rest of the clock API. In the event of an error clk_register will return an
1368 * error code; drivers must test for an error code after calling clk_register.
1369 */
1370struct clk *clk_register(struct device *dev, struct clk_hw *hw)
1371{
1372    int i, ret;
1373    struct clk *clk;
1374
1375    clk = kzalloc(sizeof(*clk), GFP_KERNEL);
1376    if (!clk) {
1377        pr_err("%s: could not allocate clk\n", __func__);
1378        ret = -ENOMEM;
1379        goto fail_out;
1380    }
1381
1382    clk->name = kstrdup(hw->init->name, GFP_KERNEL);
1383    if (!clk->name) {
1384        pr_err("%s: could not allocate clk->name\n", __func__);
1385        ret = -ENOMEM;
1386        goto fail_name;
1387    }
1388    clk->ops = hw->init->ops;
1389    clk->hw = hw;
1390    clk->flags = hw->init->flags;
1391    clk->num_parents = hw->init->num_parents;
1392    hw->clk = clk;
1393
1394    /* allocate local copy in case parent_names is __initdata */
1395    clk->parent_names = kzalloc((sizeof(char*) * clk->num_parents),
1396            GFP_KERNEL);
1397
1398    if (!clk->parent_names) {
1399        pr_err("%s: could not allocate clk->parent_names\n", __func__);
1400        ret = -ENOMEM;
1401        goto fail_parent_names;
1402    }
1403
1404
1405    /* copy each string name in case parent_names is __initdata */
1406    for (i = 0; i < clk->num_parents; i++) {
1407        clk->parent_names[i] = kstrdup(hw->init->parent_names[i],
1408                        GFP_KERNEL);
1409        if (!clk->parent_names[i]) {
1410            pr_err("%s: could not copy parent_names\n", __func__);
1411            ret = -ENOMEM;
1412            goto fail_parent_names_copy;
1413        }
1414    }
1415
1416    ret = __clk_init(dev, clk);
1417    if (!ret)
1418        return clk;
1419
1420fail_parent_names_copy:
1421    while (--i >= 0)
1422        kfree(clk->parent_names[i]);
1423    kfree(clk->parent_names);
1424fail_parent_names:
1425    kfree(clk->name);
1426fail_name:
1427    kfree(clk);
1428fail_out:
1429    return ERR_PTR(ret);
1430}
1431EXPORT_SYMBOL_GPL(clk_register);
1432
1433/**
1434 * clk_unregister - unregister a currently registered clock
1435 * @clk: clock to unregister
1436 *
1437 * Currently unimplemented.
1438 */
1439void clk_unregister(struct clk *clk) {}
1440EXPORT_SYMBOL_GPL(clk_unregister);
1441
1442/*** clk rate change notifiers ***/
1443
1444/**
1445 * clk_notifier_register - add a clk rate change notifier
1446 * @clk: struct clk * to watch
1447 * @nb: struct notifier_block * with callback info
1448 *
1449 * Request notification when clk's rate changes. This uses an SRCU
1450 * notifier because we want it to block and notifier unregistrations are
1451 * uncommon. The callbacks associated with the notifier must not
1452 * re-enter into the clk framework by calling any top-level clk APIs;
1453 * this will cause a nested prepare_lock mutex.
1454 *
1455 * Pre-change notifier callbacks will be passed the current, pre-change
1456 * rate of the clk via struct clk_notifier_data.old_rate. The new,
1457 * post-change rate of the clk is passed via struct
1458 * clk_notifier_data.new_rate.
1459 *
1460 * Post-change notifiers will pass the now-current, post-change rate of
1461 * the clk in both struct clk_notifier_data.old_rate and struct
1462 * clk_notifier_data.new_rate.
1463 *
1464 * Abort-change notifiers are effectively the opposite of pre-change
1465 * notifiers: the original pre-change clk rate is passed in via struct
1466 * clk_notifier_data.new_rate and the failed post-change rate is passed
1467 * in via struct clk_notifier_data.old_rate.
1468 *
1469 * clk_notifier_register() must be called from non-atomic context.
1470 * Returns -EINVAL if called with null arguments, -ENOMEM upon
1471 * allocation failure; otherwise, passes along the return value of
1472 * srcu_notifier_chain_register().
1473 */
1474int clk_notifier_register(struct clk *clk, struct notifier_block *nb)
1475{
1476    struct clk_notifier *cn;
1477    int ret = -ENOMEM;
1478
1479    if (!clk || !nb)
1480        return -EINVAL;
1481
1482    mutex_lock(&prepare_lock);
1483
1484    /* search the list of notifiers for this clk */
1485    list_for_each_entry(cn, &clk_notifier_list, node)
1486        if (cn->clk == clk)
1487            break;
1488
1489    /* if clk wasn't in the notifier list, allocate new clk_notifier */
1490    if (cn->clk != clk) {
1491        cn = kzalloc(sizeof(struct clk_notifier), GFP_KERNEL);
1492        if (!cn)
1493            goto out;
1494
1495        cn->clk = clk;
1496        srcu_init_notifier_head(&cn->notifier_head);
1497
1498        list_add(&cn->node, &clk_notifier_list);
1499    }
1500
1501    ret = srcu_notifier_chain_register(&cn->notifier_head, nb);
1502
1503    clk->notifier_count++;
1504
1505out:
1506    mutex_unlock(&prepare_lock);
1507
1508    return ret;
1509}
1510EXPORT_SYMBOL_GPL(clk_notifier_register);
1511
1512/**
1513 * clk_notifier_unregister - remove a clk rate change notifier
1514 * @clk: struct clk *
1515 * @nb: struct notifier_block * with callback info
1516 *
1517 * Request no further notification for changes to 'clk' and frees memory
1518 * allocated in clk_notifier_register.
1519 *
1520 * Returns -EINVAL if called with null arguments; otherwise, passes
1521 * along the return value of srcu_notifier_chain_unregister().
1522 */
1523int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb)
1524{
1525    struct clk_notifier *cn = NULL;
1526    int ret = -EINVAL;
1527
1528    if (!clk || !nb)
1529        return -EINVAL;
1530
1531    mutex_lock(&prepare_lock);
1532
1533    list_for_each_entry(cn, &clk_notifier_list, node)
1534        if (cn->clk == clk)
1535            break;
1536
1537    if (cn->clk == clk) {
1538        ret = srcu_notifier_chain_unregister(&cn->notifier_head, nb);
1539
1540        clk->notifier_count--;
1541
1542        /* XXX the notifier code should handle this better */
1543        if (!cn->notifier_head.head) {
1544            srcu_cleanup_notifier_head(&cn->notifier_head);
1545            kfree(cn);
1546        }
1547
1548    } else {
1549        ret = -ENOENT;
1550    }
1551
1552    mutex_unlock(&prepare_lock);
1553
1554    return ret;
1555}
1556EXPORT_SYMBOL_GPL(clk_notifier_unregister);
1557
1558#ifdef CONFIG_OF
1559/**
1560 * struct of_clk_provider - Clock provider registration structure
1561 * @link: Entry in global list of clock providers
1562 * @node: Pointer to device tree node of clock provider
1563 * @get: Get clock callback. Returns NULL or a struct clk for the
1564 * given clock specifier
1565 * @data: context pointer to be passed into @get callback
1566 */
1567struct of_clk_provider {
1568    struct list_head link;
1569
1570    struct device_node *node;
1571    struct clk *(*get)(struct of_phandle_args *clkspec, void *data);
1572    void *data;
1573};
1574
1575static LIST_HEAD(of_clk_providers);
1576static DEFINE_MUTEX(of_clk_lock);
1577
1578struct clk *of_clk_src_simple_get(struct of_phandle_args *clkspec,
1579                     void *data)
1580{
1581    return data;
1582}
1583EXPORT_SYMBOL_GPL(of_clk_src_simple_get);
1584
1585/**
1586 * of_clk_add_provider() - Register a clock provider for a node
1587 * @np: Device node pointer associated with clock provider
1588 * @clk_src_get: callback for decoding clock
1589 * @data: context pointer for @clk_src_get callback.
1590 */
1591int of_clk_add_provider(struct device_node *np,
1592            struct clk *(*clk_src_get)(struct of_phandle_args *clkspec,
1593                           void *data),
1594            void *data)
1595{
1596    struct of_clk_provider *cp;
1597
1598    cp = kzalloc(sizeof(struct of_clk_provider), GFP_KERNEL);
1599    if (!cp)
1600        return -ENOMEM;
1601
1602    cp->node = of_node_get(np);
1603    cp->data = data;
1604    cp->get = clk_src_get;
1605
1606    mutex_lock(&of_clk_lock);
1607    list_add(&cp->link, &of_clk_providers);
1608    mutex_unlock(&of_clk_lock);
1609    pr_debug("Added clock from %s\n", np->full_name);
1610
1611    return 0;
1612}
1613EXPORT_SYMBOL_GPL(of_clk_add_provider);
1614
1615/**
1616 * of_clk_del_provider() - Remove a previously registered clock provider
1617 * @np: Device node pointer associated with clock provider
1618 */
1619void of_clk_del_provider(struct device_node *np)
1620{
1621    struct of_clk_provider *cp;
1622
1623    mutex_lock(&of_clk_lock);
1624    list_for_each_entry(cp, &of_clk_providers, link) {
1625        if (cp->node == np) {
1626            list_del(&cp->link);
1627            of_node_put(cp->node);
1628            kfree(cp);
1629            break;
1630        }
1631    }
1632    mutex_unlock(&of_clk_lock);
1633}
1634EXPORT_SYMBOL_GPL(of_clk_del_provider);
1635
1636struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
1637{
1638    struct of_clk_provider *provider;
1639    struct clk *clk = ERR_PTR(-ENOENT);
1640
1641    /* Check if we have such a provider in our array */
1642    mutex_lock(&of_clk_lock);
1643    list_for_each_entry(provider, &of_clk_providers, link) {
1644        if (provider->node == clkspec->np)
1645            clk = provider->get(clkspec, provider->data);
1646        if (!IS_ERR(clk))
1647            break;
1648    }
1649    mutex_unlock(&of_clk_lock);
1650
1651    return clk;
1652}
1653
1654const char *of_clk_get_parent_name(struct device_node *np, int index)
1655{
1656    struct of_phandle_args clkspec;
1657    const char *clk_name;
1658    int rc;
1659
1660    if (index < 0)
1661        return NULL;
1662
1663    rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index,
1664                    &clkspec);
1665    if (rc)
1666        return NULL;
1667
1668    if (of_property_read_string_index(clkspec.np, "clock-output-names",
1669                      clkspec.args_count ? clkspec.args[0] : 0,
1670                      &clk_name) < 0)
1671        clk_name = clkspec.np->name;
1672
1673    of_node_put(clkspec.np);
1674    return clk_name;
1675}
1676EXPORT_SYMBOL_GPL(of_clk_get_parent_name);
1677
1678/**
1679 * of_clk_init() - Scan and init clock providers from the DT
1680 * @matches: array of compatible values and init functions for providers.
1681 *
1682 * This function scans the device tree for matching clock providers and
1683 * calls their initialization functions
1684 */
1685void __init of_clk_init(const struct of_device_id *matches)
1686{
1687    struct device_node *np;
1688
1689    for_each_matching_node(np, matches) {
1690        const struct of_device_id *match = of_match_node(matches, np);
1691        of_clk_init_cb_t clk_init_cb = match->data;
1692        clk_init_cb(np);
1693    }
1694}
1695#endif
1696

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