/drivers/base/power/clock_ops.c

  1/*
  2 * drivers/base/power/clock_ops.c - Generic clock manipulation PM callbacks
  3 *
  4 * Copyright (c) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
  5 *
  6 * This file is released under the GPLv2.
  7 */
  8
  9#include <linux/init.h>
 10#include <linux/kernel.h>
 11#include <linux/io.h>
 12#include <linux/pm.h>
 13#include <linux/pm_runtime.h>
 14#include <linux/clk.h>
 15#include <linux/slab.h>
 16#include <linux/err.h>
 17
 18#ifdef CONFIG_PM_RUNTIME
 19
 20struct pm_runtime_clk_data {
 21	struct list_head clock_list;
 22	struct mutex lock;
 23};
 24
 25enum pce_status {
 26	PCE_STATUS_NONE = 0,
 27	PCE_STATUS_ACQUIRED,
 28	PCE_STATUS_ENABLED,
 29	PCE_STATUS_ERROR,
 30};
 31
 32struct pm_clock_entry {
 33	struct list_head node;
 34	char *con_id;
 35	struct clk *clk;
 36	enum pce_status status;
 37};
 38
 39static struct pm_runtime_clk_data *__to_prd(struct device *dev)
 40{
 41	return dev ? dev->power.subsys_data : NULL;
 42}
 43
 44/**
 45 * pm_runtime_clk_add - Start using a device clock for runtime PM.
 46 * @dev: Device whose clock is going to be used for runtime PM.
 47 * @con_id: Connection ID of the clock.
 48 *
 49 * Add the clock represented by @con_id to the list of clocks used for
 50 * the runtime PM of @dev.
 51 */
 52int pm_runtime_clk_add(struct device *dev, const char *con_id)
 53{
 54	struct pm_runtime_clk_data *prd = __to_prd(dev);
 55	struct pm_clock_entry *ce;
 56
 57	if (!prd)
 58		return -EINVAL;
 59
 60	ce = kzalloc(sizeof(*ce), GFP_KERNEL);
 61	if (!ce) {
 62		dev_err(dev, "Not enough memory for clock entry.\n");
 63		return -ENOMEM;
 64	}
 65
 66	if (con_id) {
 67		ce->con_id = kstrdup(con_id, GFP_KERNEL);
 68		if (!ce->con_id) {
 69			dev_err(dev,
 70				"Not enough memory for clock connection ID.\n");
 71			kfree(ce);
 72			return -ENOMEM;
 73		}
 74	}
 75
 76	mutex_lock(&prd->lock);
 77	list_add_tail(&ce->node, &prd->clock_list);
 78	mutex_unlock(&prd->lock);
 79	return 0;
 80}
 81
 82/**
 83 * __pm_runtime_clk_remove - Destroy runtime PM clock entry.
 84 * @ce: Runtime PM clock entry to destroy.
 85 *
 86 * This routine must be called under the mutex protecting the runtime PM list
 87 * of clocks corresponding the the @ce's device.
 88 */
 89static void __pm_runtime_clk_remove(struct pm_clock_entry *ce)
 90{
 91	if (!ce)
 92		return;
 93
 94	list_del(&ce->node);
 95
 96	if (ce->status < PCE_STATUS_ERROR) {
 97		if (ce->status == PCE_STATUS_ENABLED)
 98			clk_disable(ce->clk);
 99
100		if (ce->status >= PCE_STATUS_ACQUIRED)
101			clk_put(ce->clk);
102	}
103
104	if (ce->con_id)
105		kfree(ce->con_id);
106
107	kfree(ce);
108}
109
110/**
111 * pm_runtime_clk_remove - Stop using a device clock for runtime PM.
112 * @dev: Device whose clock should not be used for runtime PM any more.
113 * @con_id: Connection ID of the clock.
114 *
115 * Remove the clock represented by @con_id from the list of clocks used for
116 * the runtime PM of @dev.
117 */
118void pm_runtime_clk_remove(struct device *dev, const char *con_id)
119{
120	struct pm_runtime_clk_data *prd = __to_prd(dev);
121	struct pm_clock_entry *ce;
122
123	if (!prd)
124		return;
125
126	mutex_lock(&prd->lock);
127
128	list_for_each_entry(ce, &prd->clock_list, node) {
129		if (!con_id && !ce->con_id) {
130			__pm_runtime_clk_remove(ce);
131			break;
132		} else if (!con_id || !ce->con_id) {
133			continue;
134		} else if (!strcmp(con_id, ce->con_id)) {
135			__pm_runtime_clk_remove(ce);
136			break;
137		}
138	}
139
140	mutex_unlock(&prd->lock);
141}
142
143/**
144 * pm_runtime_clk_init - Initialize a device's list of runtime PM clocks.
145 * @dev: Device to initialize the list of runtime PM clocks for.
146 *
147 * Allocate a struct pm_runtime_clk_data object, initialize its lock member and
148 * make the @dev's power.subsys_data field point to it.
149 */
150int pm_runtime_clk_init(struct device *dev)
151{
152	struct pm_runtime_clk_data *prd;
153
154	prd = kzalloc(sizeof(*prd), GFP_KERNEL);
155	if (!prd) {
156		dev_err(dev, "Not enough memory fo runtime PM data.\n");
157		return -ENOMEM;
158	}
159
160	INIT_LIST_HEAD(&prd->clock_list);
161	mutex_init(&prd->lock);
162	dev->power.subsys_data = prd;
163	return 0;
164}
165
166/**
167 * pm_runtime_clk_destroy - Destroy a device's list of runtime PM clocks.
168 * @dev: Device to destroy the list of runtime PM clocks for.
169 *
170 * Clear the @dev's power.subsys_data field, remove the list of clock entries
171 * from the struct pm_runtime_clk_data object pointed to by it before and free
172 * that object.
173 */
174void pm_runtime_clk_destroy(struct device *dev)
175{
176	struct pm_runtime_clk_data *prd = __to_prd(dev);
177	struct pm_clock_entry *ce, *c;
178
179	if (!prd)
180		return;
181
182	dev->power.subsys_data = NULL;
183
184	mutex_lock(&prd->lock);
185
186	list_for_each_entry_safe_reverse(ce, c, &prd->clock_list, node)
187		__pm_runtime_clk_remove(ce);
188
189	mutex_unlock(&prd->lock);
190
191	kfree(prd);
192}
193
194/**
195 * pm_runtime_clk_acquire - Acquire a device clock.
196 * @dev: Device whose clock is to be acquired.
197 * @con_id: Connection ID of the clock.
198 */
199static void pm_runtime_clk_acquire(struct device *dev,
200				    struct pm_clock_entry *ce)
201{
202	ce->clk = clk_get(dev, ce->con_id);
203	if (IS_ERR(ce->clk)) {
204		ce->status = PCE_STATUS_ERROR;
205	} else {
206		ce->status = PCE_STATUS_ACQUIRED;
207		dev_dbg(dev, "Clock %s managed by runtime PM.\n", ce->con_id);
208	}
209}
210
211/**
212 * pm_runtime_clk_suspend - Disable clocks in a device's runtime PM clock list.
213 * @dev: Device to disable the clocks for.
214 */
215int pm_runtime_clk_suspend(struct device *dev)
216{
217	struct pm_runtime_clk_data *prd = __to_prd(dev);
218	struct pm_clock_entry *ce;
219
220	dev_dbg(dev, "%s()\n", __func__);
221
222	if (!prd)
223		return 0;
224
225	mutex_lock(&prd->lock);
226
227	list_for_each_entry_reverse(ce, &prd->clock_list, node) {
228		if (ce->status == PCE_STATUS_NONE)
229			pm_runtime_clk_acquire(dev, ce);
230
231		if (ce->status < PCE_STATUS_ERROR) {
232			clk_disable(ce->clk);
233			ce->status = PCE_STATUS_ACQUIRED;
234		}
235	}
236
237	mutex_unlock(&prd->lock);
238
239	return 0;
240}
241
242/**
243 * pm_runtime_clk_resume - Enable clocks in a device's runtime PM clock list.
244 * @dev: Device to enable the clocks for.
245 */
246int pm_runtime_clk_resume(struct device *dev)
247{
248	struct pm_runtime_clk_data *prd = __to_prd(dev);
249	struct pm_clock_entry *ce;
250
251	dev_dbg(dev, "%s()\n", __func__);
252
253	if (!prd)
254		return 0;
255
256	mutex_lock(&prd->lock);
257
258	list_for_each_entry(ce, &prd->clock_list, node) {
259		if (ce->status == PCE_STATUS_NONE)
260			pm_runtime_clk_acquire(dev, ce);
261
262		if (ce->status < PCE_STATUS_ERROR) {
263			clk_enable(ce->clk);
264			ce->status = PCE_STATUS_ENABLED;
265		}
266	}
267
268	mutex_unlock(&prd->lock);
269
270	return 0;
271}
272
273/**
274 * pm_runtime_clk_notify - Notify routine for device addition and removal.
275 * @nb: Notifier block object this function is a member of.
276 * @action: Operation being carried out by the caller.
277 * @data: Device the routine is being run for.
278 *
279 * For this function to work, @nb must be a member of an object of type
280 * struct pm_clk_notifier_block containing all of the requisite data.
281 * Specifically, the pwr_domain member of that object is copied to the device's
282 * pwr_domain field and its con_ids member is used to populate the device's list
283 * of runtime PM clocks, depending on @action.
284 *
285 * If the device's pwr_domain field is already populated with a value different
286 * from the one stored in the struct pm_clk_notifier_block object, the function
287 * does nothing.
288 */
289static int pm_runtime_clk_notify(struct notifier_block *nb,
290				 unsigned long action, void *data)
291{
292	struct pm_clk_notifier_block *clknb;
293	struct device *dev = data;
294	char **con_id;
295	int error;
296
297	dev_dbg(dev, "%s() %ld\n", __func__, action);
298
299	clknb = container_of(nb, struct pm_clk_notifier_block, nb);
300
301	switch (action) {
302	case BUS_NOTIFY_ADD_DEVICE:
303		if (dev->pwr_domain)
304			break;
305
306		error = pm_runtime_clk_init(dev);
307		if (error)
308			break;
309
310		dev->pwr_domain = clknb->pwr_domain;
311		if (clknb->con_ids[0]) {
312			for (con_id = clknb->con_ids; *con_id; con_id++)
313				pm_runtime_clk_add(dev, *con_id);
314		} else {
315			pm_runtime_clk_add(dev, NULL);
316		}
317
318		break;
319	case BUS_NOTIFY_DEL_DEVICE:
320		if (dev->pwr_domain != clknb->pwr_domain)
321			break;
322
323		dev->pwr_domain = NULL;
324		pm_runtime_clk_destroy(dev);
325		break;
326	}
327
328	return 0;
329}
330
331#else /* !CONFIG_PM_RUNTIME */
332
333/**
334 * enable_clock - Enable a device clock.
335 * @dev: Device whose clock is to be enabled.
336 * @con_id: Connection ID of the clock.
337 */
338static void enable_clock(struct device *dev, const char *con_id)
339{
340	struct clk *clk;
341
342	clk = clk_get(dev, con_id);
343	if (!IS_ERR(clk)) {
344		clk_enable(clk);
345		clk_put(clk);
346		dev_info(dev, "Runtime PM disabled, clock forced on.\n");
347	}
348}
349
350/**
351 * disable_clock - Disable a device clock.
352 * @dev: Device whose clock is to be disabled.
353 * @con_id: Connection ID of the clock.
354 */
355static void disable_clock(struct device *dev, const char *con_id)
356{
357	struct clk *clk;
358
359	clk = clk_get(dev, con_id);
360	if (!IS_ERR(clk)) {
361		clk_disable(clk);
362		clk_put(clk);
363		dev_info(dev, "Runtime PM disabled, clock forced off.\n");
364	}
365}
366
367/**
368 * pm_runtime_clk_notify - Notify routine for device addition and removal.
369 * @nb: Notifier block object this function is a member of.
370 * @action: Operation being carried out by the caller.
371 * @data: Device the routine is being run for.
372 *
373 * For this function to work, @nb must be a member of an object of type
374 * struct pm_clk_notifier_block containing all of the requisite data.
375 * Specifically, the con_ids member of that object is used to enable or disable
376 * the device's clocks, depending on @action.
377 */
378static int pm_runtime_clk_notify(struct notifier_block *nb,
379				 unsigned long action, void *data)
380{
381	struct pm_clk_notifier_block *clknb;
382	struct device *dev = data;
383	char **con_id;
384
385	dev_dbg(dev, "%s() %ld\n", __func__, action);
386
387	clknb = container_of(nb, struct pm_clk_notifier_block, nb);
388
389	switch (action) {
390	case BUS_NOTIFY_BIND_DRIVER:
391		if (clknb->con_ids[0]) {
392			for (con_id = clknb->con_ids; *con_id; con_id++)
393				enable_clock(dev, *con_id);
394		} else {
395			enable_clock(dev, NULL);
396		}
397		break;
398	case BUS_NOTIFY_UNBOUND_DRIVER:
399		if (clknb->con_ids[0]) {
400			for (con_id = clknb->con_ids; *con_id; con_id++)
401				disable_clock(dev, *con_id);
402		} else {
403			disable_clock(dev, NULL);
404		}
405		break;
406	}
407
408	return 0;
409}
410
411#endif /* !CONFIG_PM_RUNTIME */
412
413/**
414 * pm_runtime_clk_add_notifier - Add bus type notifier for runtime PM clocks.
415 * @bus: Bus type to add the notifier to.
416 * @clknb: Notifier to be added to the given bus type.
417 *
418 * The nb member of @clknb is not expected to be initialized and its
419 * notifier_call member will be replaced with pm_runtime_clk_notify().  However,
420 * the remaining members of @clknb should be populated prior to calling this
421 * routine.
422 */
423void pm_runtime_clk_add_notifier(struct bus_type *bus,
424				 struct pm_clk_notifier_block *clknb)
425{
426	if (!bus || !clknb)
427		return;
428
429	clknb->nb.notifier_call = pm_runtime_clk_notify;
430	bus_register_notifier(bus, &clknb->nb);
431}