clock_ops.c

  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 * 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 */
272int 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
307error:
308	while (i--)
309		pm_clk_remove_clk(dev, clks[i]);
310
311	kfree(clks);
312
313	return ret;
314}
315EXPORT_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 */
321static 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 */
354void 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}
380EXPORT_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 */
389void 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}
398EXPORT_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 */
407int pm_clk_create(struct device *dev)
408{
409	return dev_pm_get_subsys_data(dev);
410}
411EXPORT_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 */
421void 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}
447EXPORT_SYMBOL_GPL(pm_clk_destroy);
448
449static void pm_clk_destroy_action(void *data)
450{
451	pm_clk_destroy(data);
452}
453
454int 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}
464EXPORT_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 */
470int 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}
502EXPORT_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 */
508int 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}
531EXPORT_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 */
549static 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
591int 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}
612EXPORT_SYMBOL_GPL(pm_clk_runtime_suspend);
613
614int 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}
628EXPORT_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 */
637static 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 */
654static 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 */
677static 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 */
723void 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}
732EXPORT_SYMBOL_GPL(pm_clk_add_notifier);