1// SPDX-License-Identifier: GPL-2.0
2/*
3 * drivers/base/power/clock_ops.c - Generic clock manipulation PM callbacks
4 *
5 * Copyright (c) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
6 */
7
8#include <linux/kernel.h>
9#include <linux/device.h>
10#include <linux/io.h>
11#include <linux/pm.h>
12#include <linux/pm_clock.h>
13#include <linux/clk.h>
14#include <linux/clkdev.h>
15#include <linux/of_clk.h>
16#include <linux/slab.h>
17#include <linux/err.h>
18#include <linux/pm_domain.h>
19#include <linux/pm_runtime.h>
20
21#ifdef CONFIG_PM_CLK
22
23enum pce_status {
24	PCE_STATUS_NONE = 0,
25	PCE_STATUS_ACQUIRED,
26	PCE_STATUS_PREPARED,
27	PCE_STATUS_ENABLED,
28	PCE_STATUS_ERROR,
29};
30
31struct pm_clock_entry {
32	struct list_head node;
33	char *con_id;
34	struct clk *clk;
35	enum pce_status status;
36	bool enabled_when_prepared;
37};
38
39/**
40 * pm_clk_list_lock - ensure exclusive access for modifying the PM clock
41 *		      entry list.
42 * @psd: pm_subsys_data instance corresponding to the PM clock entry list
43 *	 and clk_op_might_sleep count to be modified.
44 *
45 * Get exclusive access before modifying the PM clock entry list and the
46 * clock_op_might_sleep count to guard against concurrent modifications.
47 * This also protects against a concurrent clock_op_might_sleep and PM clock
48 * entry list usage in pm_clk_suspend()/pm_clk_resume() that may or may not
49 * happen in atomic context, hence both the mutex and the spinlock must be
50 * taken here.
51 */
52static void pm_clk_list_lock(struct pm_subsys_data *psd)
53	__acquires(&psd->lock)
54{
55	mutex_lock(&psd->clock_mutex);
56	spin_lock_irq(&psd->lock);
57}
58
59/**
60 * pm_clk_list_unlock - counterpart to pm_clk_list_lock().
61 * @psd: the same pm_subsys_data instance previously passed to
62 *	 pm_clk_list_lock().
63 */
64static void pm_clk_list_unlock(struct pm_subsys_data *psd)
65	__releases(&psd->lock)
66{
67	spin_unlock_irq(&psd->lock);
68	mutex_unlock(&psd->clock_mutex);
69}
70
71/**
72 * pm_clk_op_lock - ensure exclusive access for performing clock operations.
73 * @psd: pm_subsys_data instance corresponding to the PM clock entry list
74 *	 and clk_op_might_sleep count being used.
75 * @flags: stored irq flags.
76 * @fn: string for the caller function's name.
77 *
78 * This is used by pm_clk_suspend() and pm_clk_resume() to guard
79 * against concurrent modifications to the clock entry list and the
80 * clock_op_might_sleep count. If clock_op_might_sleep is != 0 then
81 * only the mutex can be locked and those functions can only be used in
82 * non atomic context. If clock_op_might_sleep == 0 then these functions
83 * may be used in any context and only the spinlock can be locked.
84 * Returns -EINVAL if called in atomic context when clock ops might sleep.
85 */
86static int pm_clk_op_lock(struct pm_subsys_data *psd, unsigned long *flags,
87			  const char *fn)
88	/* sparse annotations don't work here as exit state isn't static */
89{
90	bool atomic_context = in_atomic() || irqs_disabled();
91
92try_again:
93	spin_lock_irqsave(&psd->lock, *flags);
94	if (!psd->clock_op_might_sleep) {
95		/* the __release is there to work around sparse limitations */
96		__release(&psd->lock);
97		return 0;
98	}
99
100	/* bail out if in atomic context */
101	if (atomic_context) {
102		pr_err("%s: atomic context with clock_ops_might_sleep = %d",
103		       fn, psd->clock_op_might_sleep);
104		spin_unlock_irqrestore(&psd->lock, *flags);
105		might_sleep();
106		return -EPERM;
107	}
108
109	/* we must switch to the mutex */
110	spin_unlock_irqrestore(&psd->lock, *flags);
111	mutex_lock(&psd->clock_mutex);
112
113	/*
114	 * There was a possibility for psd->clock_op_might_sleep
115	 * to become 0 above. Keep the mutex only if not the case.
116	 */
117	if (likely(psd->clock_op_might_sleep))
118		return 0;
119
120	mutex_unlock(&psd->clock_mutex);
121	goto try_again;
122}
123
124/**
125 * pm_clk_op_unlock - counterpart to pm_clk_op_lock().
126 * @psd: the same pm_subsys_data instance previously passed to
127 *	 pm_clk_op_lock().
128 * @flags: irq flags provided by pm_clk_op_lock().
129 */
130static void pm_clk_op_unlock(struct pm_subsys_data *psd, unsigned long *flags)
131	/* sparse annotations don't work here as entry state isn't static */
132{
133	if (psd->clock_op_might_sleep) {
134		mutex_unlock(&psd->clock_mutex);
135	} else {
136		/* the __acquire is there to work around sparse limitations */
137		__acquire(&psd->lock);
138		spin_unlock_irqrestore(&psd->lock, *flags);
139	}
140}
141
142/**
143 * __pm_clk_enable - Enable a clock, reporting any errors
144 * @dev: The device for the given clock
145 * @ce: PM clock entry corresponding to the clock.
146 */
147static inline void __pm_clk_enable(struct device *dev, struct pm_clock_entry *ce)
148{
149	int ret;
150
151	switch (ce->status) {
152	case PCE_STATUS_ACQUIRED:
153		ret = clk_prepare_enable(ce->clk);
154		break;
155	case PCE_STATUS_PREPARED:
156		ret = clk_enable(ce->clk);
157		break;
158	default:
159		return;
160	}
161	if (!ret)
162		ce->status = PCE_STATUS_ENABLED;
163	else
164		dev_err(dev, "%s: failed to enable clk %p, error %d\n",
165			__func__, ce->clk, ret);
166}
167
168/**
169 * pm_clk_acquire - Acquire a device clock.
170 * @dev: Device whose clock is to be acquired.
171 * @ce: PM clock entry corresponding to the clock.
172 */
173static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce)
174{
175	if (!ce->clk)
176		ce->clk = clk_get(dev, ce->con_id);
177	if (IS_ERR(ce->clk)) {
178		ce->status = PCE_STATUS_ERROR;
179		return;
180	} else if (clk_is_enabled_when_prepared(ce->clk)) {
181		/* we defer preparing the clock in that case */
182		ce->status = PCE_STATUS_ACQUIRED;
183		ce->enabled_when_prepared = true;
184	} else if (clk_prepare(ce->clk)) {
185		ce->status = PCE_STATUS_ERROR;
186		dev_err(dev, "clk_prepare() failed\n");
187		return;
188	} else {
189		ce->status = PCE_STATUS_PREPARED;
190	}
191	dev_dbg(dev, "Clock %pC con_id %s managed by runtime PM.\n",
192		ce->clk, ce->con_id);
193}
194
195static int __pm_clk_add(struct device *dev, const char *con_id,
196			struct clk *clk)
197{
198	struct pm_subsys_data *psd = dev_to_psd(dev);
199	struct pm_clock_entry *ce;
200
201	if (!psd)
202		return -EINVAL;
203
204	ce = kzalloc(sizeof(*ce), GFP_KERNEL);
205	if (!ce)
206		return -ENOMEM;
207
208	if (con_id) {
209		ce->con_id = kstrdup(con_id, GFP_KERNEL);
210		if (!ce->con_id) {
211			kfree(ce);
212			return -ENOMEM;
213		}
214	} else {
215		if (IS_ERR(clk)) {
216			kfree(ce);
217			return -ENOENT;
218		}
219		ce->clk = clk;
220	}
221
222	pm_clk_acquire(dev, ce);
223
224	pm_clk_list_lock(psd);
225	list_add_tail(&ce->node, &psd->clock_list);
226	if (ce->enabled_when_prepared)
227		psd->clock_op_might_sleep++;
228	pm_clk_list_unlock(psd);
229	return 0;
230}
231
232/**
233 * pm_clk_add - Start using a device clock for power management.
234 * @dev: Device whose clock is going to be used for power management.
235 * @con_id: Connection ID of the clock.
236 *
237 * Add the clock represented by @con_id to the list of clocks used for
238 * the power management of @dev.
239 */
240int pm_clk_add(struct device *dev, const char *con_id)
241{
242	return __pm_clk_add(dev, con_id, NULL);
243}
244EXPORT_SYMBOL_GPL(pm_clk_add);
245
246/**
247 * pm_clk_add_clk - Start using a device clock for power management.
248 * @dev: Device whose clock is going to be used for power management.
249 * @clk: Clock pointer
250 *
251 * Add the clock to the list of clocks used for the power management of @dev.
252 * The power-management code will take control of the clock reference, so
253 * callers should not call clk_put() on @clk after this function sucessfully
254 * returned.
255 */
256int pm_clk_add_clk(struct device *dev, struct clk *clk)
257{
258	return __pm_clk_add(dev, NULL, clk);
259}
260EXPORT_SYMBOL_GPL(pm_clk_add_clk);
261
262
263/**
264 * of_pm_clk_add_clk - Start using a device clock for power management.
265 * @dev: Device whose clock is going to be used for power management.
266 * @name: Name of clock that is going to be used for power management.
267 *
268 * Add the clock described in the 'clocks' device-tree node that matches
269 * with the 'name' provided, to the list of clocks used for the power
270 * management of @dev. On success, returns 0. Returns a negative error
271 * code if the clock is not found or cannot be added.
272 */
273int of_pm_clk_add_clk(struct device *dev, const char *name)
274{
275	struct clk *clk;
276	int ret;
277
278	if (!dev || !dev->of_node || !name)
279		return -EINVAL;
280
281	clk = of_clk_get_by_name(dev->of_node, name);
282	if (IS_ERR(clk))
283		return PTR_ERR(clk);
284
285	ret = pm_clk_add_clk(dev, clk);
286	if (ret) {
287		clk_put(clk);
288		return ret;
289	}
290
291	return 0;
292}
293EXPORT_SYMBOL_GPL(of_pm_clk_add_clk);
294
295/**
296 * of_pm_clk_add_clks - Start using device clock(s) for power management.
297 * @dev: Device whose clock(s) is going to be used for power management.
298 *
299 * Add a series of clocks described in the 'clocks' device-tree node for
300 * a device to the list of clocks used for the power management of @dev.
301 * On success, returns the number of clocks added. Returns a negative
302 * error code if there are no clocks in the device node for the device
303 * or if adding a clock fails.
304 */
305int of_pm_clk_add_clks(struct device *dev)
306{
307	struct clk **clks;
308	int i, count;
309	int ret;
310
311	if (!dev || !dev->of_node)
312		return -EINVAL;
313
314	count = of_clk_get_parent_count(dev->of_node);
315	if (count <= 0)
316		return -ENODEV;
317
318	clks = kcalloc(count, sizeof(*clks), GFP_KERNEL);
319	if (!clks)
320		return -ENOMEM;
321
322	for (i = 0; i < count; i++) {
323		clks[i] = of_clk_get(dev->of_node, i);
324		if (IS_ERR(clks[i])) {
325			ret = PTR_ERR(clks[i]);
326			goto error;
327		}
328
329		ret = pm_clk_add_clk(dev, clks[i]);
330		if (ret) {
331			clk_put(clks[i]);
332			goto error;
333		}
334	}
335
336	kfree(clks);
337
338	return i;
339
340error:
341	while (i--)
342		pm_clk_remove_clk(dev, clks[i]);
343
344	kfree(clks);
345
346	return ret;
347}
348EXPORT_SYMBOL_GPL(of_pm_clk_add_clks);
349
350/**
351 * __pm_clk_remove - Destroy PM clock entry.
352 * @ce: PM clock entry to destroy.
353 */
354static void __pm_clk_remove(struct pm_clock_entry *ce)
355{
356	if (!ce)
357		return;
358
359	switch (ce->status) {
360	case PCE_STATUS_ENABLED:
361		clk_disable(ce->clk);
362		fallthrough;
363	case PCE_STATUS_PREPARED:
364		clk_unprepare(ce->clk);
365		fallthrough;
366	case PCE_STATUS_ACQUIRED:
367	case PCE_STATUS_ERROR:
368		if (!IS_ERR(ce->clk))
369			clk_put(ce->clk);
370		break;
371	default:
372		break;
373	}
374
375	kfree(ce->con_id);
376	kfree(ce);
377}
378
379/**
380 * pm_clk_remove - Stop using a device clock for power management.
381 * @dev: Device whose clock should not be used for PM any more.
382 * @con_id: Connection ID of the clock.
383 *
384 * Remove the clock represented by @con_id from the list of clocks used for
385 * the power management of @dev.
386 */
387void pm_clk_remove(struct device *dev, const char *con_id)
388{
389	struct pm_subsys_data *psd = dev_to_psd(dev);
390	struct pm_clock_entry *ce;
391
392	if (!psd)
393		return;
394
395	pm_clk_list_lock(psd);
396
397	list_for_each_entry(ce, &psd->clock_list, node) {
398		if (!con_id && !ce->con_id)
399			goto remove;
400		else if (!con_id || !ce->con_id)
401			continue;
402		else if (!strcmp(con_id, ce->con_id))
403			goto remove;
404	}
405
406	pm_clk_list_unlock(psd);
407	return;
408
409 remove:
410	list_del(&ce->node);
411	if (ce->enabled_when_prepared)
412		psd->clock_op_might_sleep--;
413	pm_clk_list_unlock(psd);
414
415	__pm_clk_remove(ce);
416}
417EXPORT_SYMBOL_GPL(pm_clk_remove);
418
419/**
420 * pm_clk_remove_clk - Stop using a device clock for power management.
421 * @dev: Device whose clock should not be used for PM any more.
422 * @clk: Clock pointer
423 *
424 * Remove the clock pointed to by @clk from the list of clocks used for
425 * the power management of @dev.
426 */
427void pm_clk_remove_clk(struct device *dev, struct clk *clk)
428{
429	struct pm_subsys_data *psd = dev_to_psd(dev);
430	struct pm_clock_entry *ce;
431
432	if (!psd || !clk)
433		return;
434
435	pm_clk_list_lock(psd);
436
437	list_for_each_entry(ce, &psd->clock_list, node) {
438		if (clk == ce->clk)
439			goto remove;
440	}
441
442	pm_clk_list_unlock(psd);
443	return;
444
445 remove:
446	list_del(&ce->node);
447	if (ce->enabled_when_prepared)
448		psd->clock_op_might_sleep--;
449	pm_clk_list_unlock(psd);
450
451	__pm_clk_remove(ce);
452}
453EXPORT_SYMBOL_GPL(pm_clk_remove_clk);
454
455/**
456 * pm_clk_init - Initialize a device's list of power management clocks.
457 * @dev: Device to initialize the list of PM clocks for.
458 *
459 * Initialize the lock and clock_list members of the device's pm_subsys_data
460 * object, set the count of clocks that might sleep to 0.
461 */
462void pm_clk_init(struct device *dev)
463{
464	struct pm_subsys_data *psd = dev_to_psd(dev);
465	if (psd) {
466		INIT_LIST_HEAD(&psd->clock_list);
467		mutex_init(&psd->clock_mutex);
468		psd->clock_op_might_sleep = 0;
469	}
470}
471EXPORT_SYMBOL_GPL(pm_clk_init);
472
473/**
474 * pm_clk_create - Create and initialize a device's list of PM clocks.
475 * @dev: Device to create and initialize the list of PM clocks for.
476 *
477 * Allocate a struct pm_subsys_data object, initialize its lock and clock_list
478 * members and make the @dev's power.subsys_data field point to it.
479 */
480int pm_clk_create(struct device *dev)
481{
482	return dev_pm_get_subsys_data(dev);
483}
484EXPORT_SYMBOL_GPL(pm_clk_create);
485
486/**
487 * pm_clk_destroy - Destroy a device's list of power management clocks.
488 * @dev: Device to destroy the list of PM clocks for.
489 *
490 * Clear the @dev's power.subsys_data field, remove the list of clock entries
491 * from the struct pm_subsys_data object pointed to by it before and free
492 * that object.
493 */
494void pm_clk_destroy(struct device *dev)
495{
496	struct pm_subsys_data *psd = dev_to_psd(dev);
497	struct pm_clock_entry *ce, *c;
498	struct list_head list;
499
500	if (!psd)
501		return;
502
503	INIT_LIST_HEAD(&list);
504
505	pm_clk_list_lock(psd);
506
507	list_for_each_entry_safe_reverse(ce, c, &psd->clock_list, node)
508		list_move(&ce->node, &list);
509	psd->clock_op_might_sleep = 0;
510
511	pm_clk_list_unlock(psd);
512
513	dev_pm_put_subsys_data(dev);
514
515	list_for_each_entry_safe_reverse(ce, c, &list, node) {
516		list_del(&ce->node);
517		__pm_clk_remove(ce);
518	}
519}
520EXPORT_SYMBOL_GPL(pm_clk_destroy);
521
522static void pm_clk_destroy_action(void *data)
523{
524	pm_clk_destroy(data);
525}
526
527int devm_pm_clk_create(struct device *dev)
528{
529	int ret;
530
531	ret = pm_clk_create(dev);
532	if (ret)
533		return ret;
534
535	return devm_add_action_or_reset(dev, pm_clk_destroy_action, dev);
536}
537EXPORT_SYMBOL_GPL(devm_pm_clk_create);
538
539/**
540 * pm_clk_suspend - Disable clocks in a device's PM clock list.
541 * @dev: Device to disable the clocks for.
542 */
543int pm_clk_suspend(struct device *dev)
544{
545	struct pm_subsys_data *psd = dev_to_psd(dev);
546	struct pm_clock_entry *ce;
547	unsigned long flags;
548	int ret;
549
550	dev_dbg(dev, "%s()\n", __func__);
551
552	if (!psd)
553		return 0;
554
555	ret = pm_clk_op_lock(psd, &flags, __func__);
556	if (ret)
557		return ret;
558
559	list_for_each_entry_reverse(ce, &psd->clock_list, node) {
560		if (ce->status == PCE_STATUS_ENABLED) {
561			if (ce->enabled_when_prepared) {
562				clk_disable_unprepare(ce->clk);
563				ce->status = PCE_STATUS_ACQUIRED;
564			} else {
565				clk_disable(ce->clk);
566				ce->status = PCE_STATUS_PREPARED;
567			}
568		}
569	}
570
571	pm_clk_op_unlock(psd, &flags);
572
573	return 0;
574}
575EXPORT_SYMBOL_GPL(pm_clk_suspend);
576
577/**
578 * pm_clk_resume - Enable clocks in a device's PM clock list.
579 * @dev: Device to enable the clocks for.
580 */
581int pm_clk_resume(struct device *dev)
582{
583	struct pm_subsys_data *psd = dev_to_psd(dev);
584	struct pm_clock_entry *ce;
585	unsigned long flags;
586	int ret;
587
588	dev_dbg(dev, "%s()\n", __func__);
589
590	if (!psd)
591		return 0;
592
593	ret = pm_clk_op_lock(psd, &flags, __func__);
594	if (ret)
595		return ret;
596
597	list_for_each_entry(ce, &psd->clock_list, node)
598		__pm_clk_enable(dev, ce);
599
600	pm_clk_op_unlock(psd, &flags);
601
602	return 0;
603}
604EXPORT_SYMBOL_GPL(pm_clk_resume);
605
606/**
607 * pm_clk_notify - Notify routine for device addition and removal.
608 * @nb: Notifier block object this function is a member of.
609 * @action: Operation being carried out by the caller.
610 * @data: Device the routine is being run for.
611 *
612 * For this function to work, @nb must be a member of an object of type
613 * struct pm_clk_notifier_block containing all of the requisite data.
614 * Specifically, the pm_domain member of that object is copied to the device's
615 * pm_domain field and its con_ids member is used to populate the device's list
616 * of PM clocks, depending on @action.
617 *
618 * If the device's pm_domain field is already populated with a value different
619 * from the one stored in the struct pm_clk_notifier_block object, the function
620 * does nothing.
621 */
622static int pm_clk_notify(struct notifier_block *nb,
623				 unsigned long action, void *data)
624{
625	struct pm_clk_notifier_block *clknb;
626	struct device *dev = data;
627	char **con_id;
628	int error;
629
630	dev_dbg(dev, "%s() %ld\n", __func__, action);
631
632	clknb = container_of(nb, struct pm_clk_notifier_block, nb);
633
634	switch (action) {
635	case BUS_NOTIFY_ADD_DEVICE:
636		if (dev->pm_domain)
637			break;
638
639		error = pm_clk_create(dev);
640		if (error)
641			break;
642
643		dev_pm_domain_set(dev, clknb->pm_domain);
644		if (clknb->con_ids[0]) {
645			for (con_id = clknb->con_ids; *con_id; con_id++)
646				pm_clk_add(dev, *con_id);
647		} else {
648			pm_clk_add(dev, NULL);
649		}
650
651		break;
652	case BUS_NOTIFY_DEL_DEVICE:
653		if (dev->pm_domain != clknb->pm_domain)
654			break;
655
656		dev_pm_domain_set(dev, NULL);
657		pm_clk_destroy(dev);
658		break;
659	}
660
661	return 0;
662}
663
664int pm_clk_runtime_suspend(struct device *dev)
665{
666	int ret;
667
668	dev_dbg(dev, "%s\n", __func__);
669
670	ret = pm_generic_runtime_suspend(dev);
671	if (ret) {
672		dev_err(dev, "failed to suspend device\n");
673		return ret;
674	}
675
676	ret = pm_clk_suspend(dev);
677	if (ret) {
678		dev_err(dev, "failed to suspend clock\n");
679		pm_generic_runtime_resume(dev);
680		return ret;
681	}
682
683	return 0;
684}
685EXPORT_SYMBOL_GPL(pm_clk_runtime_suspend);
686
687int pm_clk_runtime_resume(struct device *dev)
688{
689	int ret;
690
691	dev_dbg(dev, "%s\n", __func__);
692
693	ret = pm_clk_resume(dev);
694	if (ret) {
695		dev_err(dev, "failed to resume clock\n");
696		return ret;
697	}
698
699	return pm_generic_runtime_resume(dev);
700}
701EXPORT_SYMBOL_GPL(pm_clk_runtime_resume);
702
703#else /* !CONFIG_PM_CLK */
704
705/**
706 * enable_clock - Enable a device clock.
707 * @dev: Device whose clock is to be enabled.
708 * @con_id: Connection ID of the clock.
709 */
710static void enable_clock(struct device *dev, const char *con_id)
711{
712	struct clk *clk;
713
714	clk = clk_get(dev, con_id);
715	if (!IS_ERR(clk)) {
716		clk_prepare_enable(clk);
717		clk_put(clk);
718		dev_info(dev, "Runtime PM disabled, clock forced on.\n");
719	}
720}
721
722/**
723 * disable_clock - Disable a device clock.
724 * @dev: Device whose clock is to be disabled.
725 * @con_id: Connection ID of the clock.
726 */
727static void disable_clock(struct device *dev, const char *con_id)
728{
729	struct clk *clk;
730
731	clk = clk_get(dev, con_id);
732	if (!IS_ERR(clk)) {
733		clk_disable_unprepare(clk);
734		clk_put(clk);
735		dev_info(dev, "Runtime PM disabled, clock forced off.\n");
736	}
737}
738
739/**
740 * pm_clk_notify - Notify routine for device addition and removal.
741 * @nb: Notifier block object this function is a member of.
742 * @action: Operation being carried out by the caller.
743 * @data: Device the routine is being run for.
744 *
745 * For this function to work, @nb must be a member of an object of type
746 * struct pm_clk_notifier_block containing all of the requisite data.
747 * Specifically, the con_ids member of that object is used to enable or disable
748 * the device's clocks, depending on @action.
749 */
750static int pm_clk_notify(struct notifier_block *nb,
751				 unsigned long action, void *data)
752{
753	struct pm_clk_notifier_block *clknb;
754	struct device *dev = data;
755	char **con_id;
756
757	dev_dbg(dev, "%s() %ld\n", __func__, action);
758
759	clknb = container_of(nb, struct pm_clk_notifier_block, nb);
760
761	switch (action) {
762	case BUS_NOTIFY_BIND_DRIVER:
763		if (clknb->con_ids[0]) {
764			for (con_id = clknb->con_ids; *con_id; con_id++)
765				enable_clock(dev, *con_id);
766		} else {
767			enable_clock(dev, NULL);
768		}
769		break;
770	case BUS_NOTIFY_DRIVER_NOT_BOUND:
771	case BUS_NOTIFY_UNBOUND_DRIVER:
772		if (clknb->con_ids[0]) {
773			for (con_id = clknb->con_ids; *con_id; con_id++)
774				disable_clock(dev, *con_id);
775		} else {
776			disable_clock(dev, NULL);
777		}
778		break;
779	}
780
781	return 0;
782}
783
784#endif /* !CONFIG_PM_CLK */
785
786/**
787 * pm_clk_add_notifier - Add bus type notifier for power management clocks.
788 * @bus: Bus type to add the notifier to.
789 * @clknb: Notifier to be added to the given bus type.
790 *
791 * The nb member of @clknb is not expected to be initialized and its
792 * notifier_call member will be replaced with pm_clk_notify().  However,
793 * the remaining members of @clknb should be populated prior to calling this
794 * routine.
795 */
796void pm_clk_add_notifier(const struct bus_type *bus,
797				 struct pm_clk_notifier_block *clknb)
798{
799	if (!bus || !clknb)
800		return;
801
802	clknb->nb.notifier_call = pm_clk_notify;
803	bus_register_notifier(bus, &clknb->nb);
804}
805EXPORT_SYMBOL_GPL(pm_clk_add_notifier);
806