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 
23 enum 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 
31 struct 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  */
pm_clk_list_lock(struct pm_subsys_data * psd)52 static 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  */
pm_clk_list_unlock(struct pm_subsys_data * psd)64 static 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  */
pm_clk_op_lock(struct pm_subsys_data * psd,unsigned long * flags,const char * fn)86 static 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 
92 try_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  */
pm_clk_op_unlock(struct pm_subsys_data * psd,unsigned long * flags)130 static 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  */
__pm_clk_enable(struct device * dev,struct pm_clock_entry * ce)147 static 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  */
pm_clk_acquire(struct device * dev,struct pm_clock_entry * ce)173 static 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 
__pm_clk_add(struct device * dev,const char * con_id,struct clk * clk)195 static 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  */
pm_clk_add(struct device * dev,const char * con_id)240 int pm_clk_add(struct device *dev, const char *con_id)
241 {
242 	return __pm_clk_add(dev, con_id, NULL);
243 }
244 EXPORT_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  */
pm_clk_add_clk(struct device * dev,struct clk * clk)256 int pm_clk_add_clk(struct device *dev, struct clk *clk)
257 {
258 	return __pm_clk_add(dev, NULL, clk);
259 }
260 EXPORT_SYMBOL_GPL(pm_clk_add_clk);
261 
262 /**
263  * of_pm_clk_add_clks - Start using device clock(s) for power management.
264  * @dev: Device whose clock(s) is going to be used for power management.
265  *
266  * Add a series of clocks described in the 'clocks' device-tree node for
267  * a device to the list of clocks used for the power management of @dev.
268  * On success, returns the number of clocks added. Returns a negative
269  * error code if there are no clocks in the device node for the device
270  * or if adding a clock fails.
271  */
of_pm_clk_add_clks(struct device * dev)272 int of_pm_clk_add_clks(struct device *dev)
273 {
274 	struct clk **clks;
275 	int i, count;
276 	int ret;
277 
278 	if (!dev || !dev->of_node)
279 		return -EINVAL;
280 
281 	count = of_clk_get_parent_count(dev->of_node);
282 	if (count <= 0)
283 		return -ENODEV;
284 
285 	clks = kcalloc(count, sizeof(*clks), GFP_KERNEL);
286 	if (!clks)
287 		return -ENOMEM;
288 
289 	for (i = 0; i < count; i++) {
290 		clks[i] = of_clk_get(dev->of_node, i);
291 		if (IS_ERR(clks[i])) {
292 			ret = PTR_ERR(clks[i]);
293 			goto error;
294 		}
295 
296 		ret = pm_clk_add_clk(dev, clks[i]);
297 		if (ret) {
298 			clk_put(clks[i]);
299 			goto error;
300 		}
301 	}
302 
303 	kfree(clks);
304 
305 	return i;
306 
307 error:
308 	while (i--)
309 		pm_clk_remove_clk(dev, clks[i]);
310 
311 	kfree(clks);
312 
313 	return ret;
314 }
315 EXPORT_SYMBOL_GPL(of_pm_clk_add_clks);
316 
317 /**
318  * __pm_clk_remove - Destroy PM clock entry.
319  * @ce: PM clock entry to destroy.
320  */
__pm_clk_remove(struct pm_clock_entry * ce)321 static void __pm_clk_remove(struct pm_clock_entry *ce)
322 {
323 	if (!ce)
324 		return;
325 
326 	switch (ce->status) {
327 	case PCE_STATUS_ENABLED:
328 		clk_disable(ce->clk);
329 		fallthrough;
330 	case PCE_STATUS_PREPARED:
331 		clk_unprepare(ce->clk);
332 		fallthrough;
333 	case PCE_STATUS_ACQUIRED:
334 	case PCE_STATUS_ERROR:
335 		if (!IS_ERR(ce->clk))
336 			clk_put(ce->clk);
337 		break;
338 	default:
339 		break;
340 	}
341 
342 	kfree(ce->con_id);
343 	kfree(ce);
344 }
345 
346 /**
347  * pm_clk_remove_clk - Stop using a device clock for power management.
348  * @dev: Device whose clock should not be used for PM any more.
349  * @clk: Clock pointer
350  *
351  * Remove the clock pointed to by @clk from the list of clocks used for
352  * the power management of @dev.
353  */
pm_clk_remove_clk(struct device * dev,struct clk * clk)354 void pm_clk_remove_clk(struct device *dev, struct clk *clk)
355 {
356 	struct pm_subsys_data *psd = dev_to_psd(dev);
357 	struct pm_clock_entry *ce;
358 
359 	if (!psd || !clk)
360 		return;
361 
362 	pm_clk_list_lock(psd);
363 
364 	list_for_each_entry(ce, &psd->clock_list, node) {
365 		if (clk == ce->clk)
366 			goto remove;
367 	}
368 
369 	pm_clk_list_unlock(psd);
370 	return;
371 
372  remove:
373 	list_del(&ce->node);
374 	if (ce->enabled_when_prepared)
375 		psd->clock_op_might_sleep--;
376 	pm_clk_list_unlock(psd);
377 
378 	__pm_clk_remove(ce);
379 }
380 EXPORT_SYMBOL_GPL(pm_clk_remove_clk);
381 
382 /**
383  * pm_clk_init - Initialize a device's list of power management clocks.
384  * @dev: Device to initialize the list of PM clocks for.
385  *
386  * Initialize the lock and clock_list members of the device's pm_subsys_data
387  * object, set the count of clocks that might sleep to 0.
388  */
pm_clk_init(struct device * dev)389 void pm_clk_init(struct device *dev)
390 {
391 	struct pm_subsys_data *psd = dev_to_psd(dev);
392 	if (psd) {
393 		INIT_LIST_HEAD(&psd->clock_list);
394 		mutex_init(&psd->clock_mutex);
395 		psd->clock_op_might_sleep = 0;
396 	}
397 }
398 EXPORT_SYMBOL_GPL(pm_clk_init);
399 
400 /**
401  * pm_clk_create - Create and initialize a device's list of PM clocks.
402  * @dev: Device to create and initialize the list of PM clocks for.
403  *
404  * Allocate a struct pm_subsys_data object, initialize its lock and clock_list
405  * members and make the @dev's power.subsys_data field point to it.
406  */
pm_clk_create(struct device * dev)407 int pm_clk_create(struct device *dev)
408 {
409 	return dev_pm_get_subsys_data(dev);
410 }
411 EXPORT_SYMBOL_GPL(pm_clk_create);
412 
413 /**
414  * pm_clk_destroy - Destroy a device's list of power management clocks.
415  * @dev: Device to destroy the list of PM clocks for.
416  *
417  * Clear the @dev's power.subsys_data field, remove the list of clock entries
418  * from the struct pm_subsys_data object pointed to by it before and free
419  * that object.
420  */
pm_clk_destroy(struct device * dev)421 void pm_clk_destroy(struct device *dev)
422 {
423 	struct pm_subsys_data *psd = dev_to_psd(dev);
424 	struct pm_clock_entry *ce, *c;
425 	struct list_head list;
426 
427 	if (!psd)
428 		return;
429 
430 	INIT_LIST_HEAD(&list);
431 
432 	pm_clk_list_lock(psd);
433 
434 	list_for_each_entry_safe_reverse(ce, c, &psd->clock_list, node)
435 		list_move(&ce->node, &list);
436 	psd->clock_op_might_sleep = 0;
437 
438 	pm_clk_list_unlock(psd);
439 
440 	dev_pm_put_subsys_data(dev);
441 
442 	list_for_each_entry_safe_reverse(ce, c, &list, node) {
443 		list_del(&ce->node);
444 		__pm_clk_remove(ce);
445 	}
446 }
447 EXPORT_SYMBOL_GPL(pm_clk_destroy);
448 
pm_clk_destroy_action(void * data)449 static void pm_clk_destroy_action(void *data)
450 {
451 	pm_clk_destroy(data);
452 }
453 
devm_pm_clk_create(struct device * dev)454 int devm_pm_clk_create(struct device *dev)
455 {
456 	int ret;
457 
458 	ret = pm_clk_create(dev);
459 	if (ret)
460 		return ret;
461 
462 	return devm_add_action_or_reset(dev, pm_clk_destroy_action, dev);
463 }
464 EXPORT_SYMBOL_GPL(devm_pm_clk_create);
465 
466 /**
467  * pm_clk_suspend - Disable clocks in a device's PM clock list.
468  * @dev: Device to disable the clocks for.
469  */
pm_clk_suspend(struct device * dev)470 int pm_clk_suspend(struct device *dev)
471 {
472 	struct pm_subsys_data *psd = dev_to_psd(dev);
473 	struct pm_clock_entry *ce;
474 	unsigned long flags;
475 	int ret;
476 
477 	dev_dbg(dev, "%s()\n", __func__);
478 
479 	if (!psd)
480 		return 0;
481 
482 	ret = pm_clk_op_lock(psd, &flags, __func__);
483 	if (ret)
484 		return ret;
485 
486 	list_for_each_entry_reverse(ce, &psd->clock_list, node) {
487 		if (ce->status == PCE_STATUS_ENABLED) {
488 			if (ce->enabled_when_prepared) {
489 				clk_disable_unprepare(ce->clk);
490 				ce->status = PCE_STATUS_ACQUIRED;
491 			} else {
492 				clk_disable(ce->clk);
493 				ce->status = PCE_STATUS_PREPARED;
494 			}
495 		}
496 	}
497 
498 	pm_clk_op_unlock(psd, &flags);
499 
500 	return 0;
501 }
502 EXPORT_SYMBOL_GPL(pm_clk_suspend);
503 
504 /**
505  * pm_clk_resume - Enable clocks in a device's PM clock list.
506  * @dev: Device to enable the clocks for.
507  */
pm_clk_resume(struct device * dev)508 int pm_clk_resume(struct device *dev)
509 {
510 	struct pm_subsys_data *psd = dev_to_psd(dev);
511 	struct pm_clock_entry *ce;
512 	unsigned long flags;
513 	int ret;
514 
515 	dev_dbg(dev, "%s()\n", __func__);
516 
517 	if (!psd)
518 		return 0;
519 
520 	ret = pm_clk_op_lock(psd, &flags, __func__);
521 	if (ret)
522 		return ret;
523 
524 	list_for_each_entry(ce, &psd->clock_list, node)
525 		__pm_clk_enable(dev, ce);
526 
527 	pm_clk_op_unlock(psd, &flags);
528 
529 	return 0;
530 }
531 EXPORT_SYMBOL_GPL(pm_clk_resume);
532 
533 /**
534  * pm_clk_notify - Notify routine for device addition and removal.
535  * @nb: Notifier block object this function is a member of.
536  * @action: Operation being carried out by the caller.
537  * @data: Device the routine is being run for.
538  *
539  * For this function to work, @nb must be a member of an object of type
540  * struct pm_clk_notifier_block containing all of the requisite data.
541  * Specifically, the pm_domain member of that object is copied to the device's
542  * pm_domain field and its con_ids member is used to populate the device's list
543  * of PM clocks, depending on @action.
544  *
545  * If the device's pm_domain field is already populated with a value different
546  * from the one stored in the struct pm_clk_notifier_block object, the function
547  * does nothing.
548  */
pm_clk_notify(struct notifier_block * nb,unsigned long action,void * data)549 static int pm_clk_notify(struct notifier_block *nb,
550 				 unsigned long action, void *data)
551 {
552 	struct pm_clk_notifier_block *clknb;
553 	struct device *dev = data;
554 	char **con_id;
555 	int error;
556 
557 	dev_dbg(dev, "%s() %ld\n", __func__, action);
558 
559 	clknb = container_of(nb, struct pm_clk_notifier_block, nb);
560 
561 	switch (action) {
562 	case BUS_NOTIFY_ADD_DEVICE:
563 		if (dev->pm_domain)
564 			break;
565 
566 		error = pm_clk_create(dev);
567 		if (error)
568 			break;
569 
570 		dev_pm_domain_set(dev, clknb->pm_domain);
571 		if (clknb->con_ids[0]) {
572 			for (con_id = clknb->con_ids; *con_id; con_id++)
573 				pm_clk_add(dev, *con_id);
574 		} else {
575 			pm_clk_add(dev, NULL);
576 		}
577 
578 		break;
579 	case BUS_NOTIFY_DEL_DEVICE:
580 		if (dev->pm_domain != clknb->pm_domain)
581 			break;
582 
583 		dev_pm_domain_set(dev, NULL);
584 		pm_clk_destroy(dev);
585 		break;
586 	}
587 
588 	return 0;
589 }
590 
pm_clk_runtime_suspend(struct device * dev)591 int pm_clk_runtime_suspend(struct device *dev)
592 {
593 	int ret;
594 
595 	dev_dbg(dev, "%s\n", __func__);
596 
597 	ret = pm_generic_runtime_suspend(dev);
598 	if (ret) {
599 		dev_err(dev, "failed to suspend device\n");
600 		return ret;
601 	}
602 
603 	ret = pm_clk_suspend(dev);
604 	if (ret) {
605 		dev_err(dev, "failed to suspend clock\n");
606 		pm_generic_runtime_resume(dev);
607 		return ret;
608 	}
609 
610 	return 0;
611 }
612 EXPORT_SYMBOL_GPL(pm_clk_runtime_suspend);
613 
pm_clk_runtime_resume(struct device * dev)614 int pm_clk_runtime_resume(struct device *dev)
615 {
616 	int ret;
617 
618 	dev_dbg(dev, "%s\n", __func__);
619 
620 	ret = pm_clk_resume(dev);
621 	if (ret) {
622 		dev_err(dev, "failed to resume clock\n");
623 		return ret;
624 	}
625 
626 	return pm_generic_runtime_resume(dev);
627 }
628 EXPORT_SYMBOL_GPL(pm_clk_runtime_resume);
629 
630 #else /* !CONFIG_PM_CLK */
631 
632 /**
633  * enable_clock - Enable a device clock.
634  * @dev: Device whose clock is to be enabled.
635  * @con_id: Connection ID of the clock.
636  */
enable_clock(struct device * dev,const char * con_id)637 static void enable_clock(struct device *dev, const char *con_id)
638 {
639 	struct clk *clk;
640 
641 	clk = clk_get(dev, con_id);
642 	if (!IS_ERR(clk)) {
643 		clk_prepare_enable(clk);
644 		clk_put(clk);
645 		dev_info(dev, "Runtime PM disabled, clock forced on.\n");
646 	}
647 }
648 
649 /**
650  * disable_clock - Disable a device clock.
651  * @dev: Device whose clock is to be disabled.
652  * @con_id: Connection ID of the clock.
653  */
disable_clock(struct device * dev,const char * con_id)654 static void disable_clock(struct device *dev, const char *con_id)
655 {
656 	struct clk *clk;
657 
658 	clk = clk_get(dev, con_id);
659 	if (!IS_ERR(clk)) {
660 		clk_disable_unprepare(clk);
661 		clk_put(clk);
662 		dev_info(dev, "Runtime PM disabled, clock forced off.\n");
663 	}
664 }
665 
666 /**
667  * pm_clk_notify - Notify routine for device addition and removal.
668  * @nb: Notifier block object this function is a member of.
669  * @action: Operation being carried out by the caller.
670  * @data: Device the routine is being run for.
671  *
672  * For this function to work, @nb must be a member of an object of type
673  * struct pm_clk_notifier_block containing all of the requisite data.
674  * Specifically, the con_ids member of that object is used to enable or disable
675  * the device's clocks, depending on @action.
676  */
pm_clk_notify(struct notifier_block * nb,unsigned long action,void * data)677 static int pm_clk_notify(struct notifier_block *nb,
678 				 unsigned long action, void *data)
679 {
680 	struct pm_clk_notifier_block *clknb;
681 	struct device *dev = data;
682 	char **con_id;
683 
684 	dev_dbg(dev, "%s() %ld\n", __func__, action);
685 
686 	clknb = container_of(nb, struct pm_clk_notifier_block, nb);
687 
688 	switch (action) {
689 	case BUS_NOTIFY_BIND_DRIVER:
690 		if (clknb->con_ids[0]) {
691 			for (con_id = clknb->con_ids; *con_id; con_id++)
692 				enable_clock(dev, *con_id);
693 		} else {
694 			enable_clock(dev, NULL);
695 		}
696 		break;
697 	case BUS_NOTIFY_DRIVER_NOT_BOUND:
698 	case BUS_NOTIFY_UNBOUND_DRIVER:
699 		if (clknb->con_ids[0]) {
700 			for (con_id = clknb->con_ids; *con_id; con_id++)
701 				disable_clock(dev, *con_id);
702 		} else {
703 			disable_clock(dev, NULL);
704 		}
705 		break;
706 	}
707 
708 	return 0;
709 }
710 
711 #endif /* !CONFIG_PM_CLK */
712 
713 /**
714  * pm_clk_add_notifier - Add bus type notifier for power management clocks.
715  * @bus: Bus type to add the notifier to.
716  * @clknb: Notifier to be added to the given bus type.
717  *
718  * The nb member of @clknb is not expected to be initialized and its
719  * notifier_call member will be replaced with pm_clk_notify().  However,
720  * the remaining members of @clknb should be populated prior to calling this
721  * routine.
722  */
pm_clk_add_notifier(const struct bus_type * bus,struct pm_clk_notifier_block * clknb)723 void pm_clk_add_notifier(const struct bus_type *bus,
724 				 struct pm_clk_notifier_block *clknb)
725 {
726 	if (!bus || !clknb)
727 		return;
728 
729 	clknb->nb.notifier_call = pm_clk_notify;
730 	bus_register_notifier(bus, &clknb->nb);
731 }
732 EXPORT_SYMBOL_GPL(pm_clk_add_notifier);
733