aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/base/power/clock_ops.c
blob: a846b2f95cfbc5bfbf253f5955da6cb8cd07804f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
/*
 * drivers/base/power/clock_ops.c - Generic clock manipulation PM callbacks
 *
 * Copyright (c) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
 *
 * This file is released under the GPLv2.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>
#include <linux/clk.h>
#include <linux/slab.h>
#include <linux/err.h>

#ifdef CONFIG_PM

struct pm_clk_data {
	struct list_head clock_list;
	struct mutex lock;
};

enum pce_status {
	PCE_STATUS_NONE = 0,
	PCE_STATUS_ACQUIRED,
	PCE_STATUS_ENABLED,
	PCE_STATUS_ERROR,
};

struct pm_clock_entry {
	struct list_head node;
	char *con_id;
	struct clk *clk;
	enum pce_status status;
};

static struct pm_clk_data *__to_pcd(struct device *dev)
{
	return dev ? dev->power.subsys_data : NULL;
}

/**
 * pm_clk_add - Start using a device clock for power management.
 * @dev: Device whose clock is going to be used for power management.
 * @con_id: Connection ID of the clock.
 *
 * Add the clock represented by @con_id to the list of clocks used for
 * the power management of @dev.
 */
int pm_clk_add(struct device *dev, const char *con_id)
{
	struct pm_clk_data *pcd = __to_pcd(dev);
	struct pm_clock_entry *ce;

	if (!pcd)
		return -EINVAL;

	ce = kzalloc(sizeof(*ce), GFP_KERNEL);
	if (!ce) {
		dev_err(dev, "Not enough memory for clock entry.\n");
		return -ENOMEM;
	}

	if (con_id) {
		ce->con_id = kstrdup(con_id, GFP_KERNEL);
		if (!ce->con_id) {
			dev_err(dev,
				"Not enough memory for clock connection ID.\n");
			kfree(ce);
			return -ENOMEM;
		}
	}

	mutex_lock(&pcd->lock);
	list_add_tail(&ce->node, &pcd->clock_list);
	mutex_unlock(&pcd->lock);
	return 0;
}

/**
 * __pm_clk_remove - Destroy PM clock entry.
 * @ce: PM clock entry to destroy.
 *
 * This routine must be called under the mutex protecting the PM list of clocks
 * corresponding the the @ce's device.
 */
static void __pm_clk_remove(struct pm_clock_entry *ce)
{
	if (!ce)
		return;

	list_del(&ce->node);

	if (ce->status < PCE_STATUS_ERROR) {
		if (ce->status == PCE_STATUS_ENABLED)
			clk_disable(ce->clk);

		if (ce->status >= PCE_STATUS_ACQUIRED)
			clk_put(ce->clk);
	}

	if (ce->con_id)
		kfree(ce->con_id);

	kfree(ce);
}

/**
 * pm_clk_remove - Stop using a device clock for power management.
 * @dev: Device whose clock should not be used for PM any more.
 * @con_id: Connection ID of the clock.
 *
 * Remove the clock represented by @con_id from the list of clocks used for
 * the power management of @dev.
 */
void pm_clk_remove(struct device *dev, const char *con_id)
{
	struct pm_clk_data *pcd = __to_pcd(dev);
	struct pm_clock_entry *ce;

	if (!pcd)
		return;

	mutex_lock(&pcd->lock);

	list_for_each_entry(ce, &pcd->clock_list, node) {
		if (!con_id && !ce->con_id) {
			__pm_clk_remove(ce);
			break;
		} else if (!con_id || !ce->con_id) {
			continue;
		} else if (!strcmp(con_id, ce->con_id)) {
			__pm_clk_remove(ce);
			break;
		}
	}

	mutex_unlock(&pcd->lock);
}

/**
 * pm_clk_init - Initialize a device's list of power management clocks.
 * @dev: Device to initialize the list of PM clocks for.
 *
 * Allocate a struct pm_clk_data object, initialize its lock member and
 * make the @dev's power.subsys_data field point to it.
 */
int pm_clk_init(struct device *dev)
{
	struct pm_clk_data *pcd;

	pcd = kzalloc(sizeof(*pcd), GFP_KERNEL);
	if (!pcd) {
		dev_err(dev, "Not enough memory for PM clock data.\n");
		return -ENOMEM;
	}

	INIT_LIST_HEAD(&pcd->clock_list);
	mutex_init(&pcd->lock);
	dev->power.subsys_data = pcd;
	return 0;
}

/**
 * pm_clk_destroy - Destroy a device's list of power management clocks.
 * @dev: Device to destroy the list of PM clocks for.
 *
 * Clear the @dev's power.subsys_data field, remove the list of clock entries
 * from the struct pm_clk_data object pointed to by it before and free
 * that object.
 */
void pm_clk_destroy(struct device *dev)
{
	struct pm_clk_data *pcd = __to_pcd(dev);
	struct pm_clock_entry *ce, *c;

	if (!pcd)
		return;

	dev->power.subsys_data = NULL;

	mutex_lock(&pcd->lock);

	list_for_each_entry_safe_reverse(ce, c, &pcd->clock_list, node)
		__pm_clk_remove(ce);

	mutex_unlock(&pcd->lock);

	kfree(pcd);
}

#endif /* CONFIG_PM */

#ifdef CONFIG_PM_RUNTIME

/**
 * pm_clk_acquire - Acquire a device clock.
 * @dev: Device whose clock is to be acquired.
 * @con_id: Connection ID of the clock.
 */
static void pm_clk_acquire(struct device *dev,
				    struct pm_clock_entry *ce)
{
	ce->clk = clk_get(dev, ce->con_id);
	if (IS_ERR(ce->clk)) {
		ce->status = PCE_STATUS_ERROR;
	} else {
		ce->status = PCE_STATUS_ACQUIRED;
		dev_dbg(dev, "Clock %s managed by runtime PM.\n", ce->con_id);
	}
}

/**
 * pm_clk_suspend - Disable clocks in a device's PM clock list.
 * @dev: Device to disable the clocks for.
 */
int pm_clk_suspend(struct device *dev)
{
	struct pm_clk_data *pcd = __to_pcd(dev);
	struct pm_clock_entry *ce;

	dev_dbg(dev, "%s()\n", __func__);

	if (!pcd)
		return 0;

	mutex_lock(&pcd->lock);

	list_for_each_entry_reverse(ce, &pcd->clock_list, node) {
		if (ce->status == PCE_STATUS_NONE)
			pm_clk_acquire(dev, ce);

		if (ce->status < PCE_STATUS_ERROR) {
			clk_disable(ce->clk);
			ce->status = PCE_STATUS_ACQUIRED;
		}
	}

	mutex_unlock(&pcd->lock);

	return 0;
}

/**
 * pm_clk_resume - Enable clocks in a device's PM clock list.
 * @dev: Device to enable the clocks for.
 */
int pm_clk_resume(struct device *dev)
{
	struct pm_clk_data *pcd = __to_pcd(dev);
	struct pm_clock_entry *ce;

	dev_dbg(dev, "%s()\n", __func__);

	if (!pcd)
		return 0;

	mutex_lock(&pcd->lock);

	list_for_each_entry(ce, &pcd->clock_list, node) {
		if (ce->status == PCE_STATUS_NONE)
			pm_clk_acquire(dev, ce);

		if (ce->status < PCE_STATUS_ERROR) {
			clk_enable(ce->clk);
			ce->status = PCE_STATUS_ENABLED;
		}
	}

	mutex_unlock(&pcd->lock);

	return 0;
}

/**
 * pm_clk_notify - Notify routine for device addition and removal.
 * @nb: Notifier block object this function is a member of.
 * @action: Operation being carried out by the caller.
 * @data: Device the routine is being run for.
 *
 * For this function to work, @nb must be a member of an object of type
 * struct pm_clk_notifier_block containing all of the requisite data.
 * Specifically, the pm_domain member of that object is copied to the device's
 * pm_domain field and its con_ids member is used to populate the device's list
 * of PM clocks, depending on @action.
 *
 * If the device's pm_domain field is already populated with a value different
 * from the one stored in the struct pm_clk_notifier_block object, the function
 * does nothing.
 */
static int pm_clk_notify(struct notifier_block *nb,
				 unsigned long action, void *data)
{
	struct pm_clk_notifier_block *clknb;
	struct device *dev = data;
	char **con_id;
	int error;

	dev_dbg(dev, "%s() %ld\n", __func__, action);

	clknb = container_of(nb, struct pm_clk_notifier_block, nb);

	switch (action) {
	case BUS_NOTIFY_ADD_DEVICE:
		if (dev->pm_domain)
			break;

		error = pm_clk_init(dev);
		if (error)
			break;

		dev->pm_domain = clknb->pm_domain;
		if (clknb->con_ids[0]) {
			for (con_id = clknb->con_ids; *con_id; con_id++)
				pm_clk_add(dev, *con_id);
		} else {
			pm_clk_add(dev, NULL);
		}

		break;
	case BUS_NOTIFY_DEL_DEVICE:
		if (dev->pm_domain != clknb->pm_domain)
			break;

		dev->pm_domain = NULL;
		pm_clk_destroy(dev);
		break;
	}

	return 0;
}

#else /* !CONFIG_PM_RUNTIME */

#ifdef CONFIG_PM

/**
 * pm_clk_suspend - Disable clocks in a device's PM clock list.
 * @dev: Device to disable the clocks for.
 */
int pm_clk_suspend(struct device *dev)
{
	struct pm_clk_data *pcd = __to_pcd(dev);
	struct pm_clock_entry *ce;

	dev_dbg(dev, "%s()\n", __func__);

	/* If there is no driver, the clocks are already disabled. */
	if (!pcd || !dev->driver)
		return 0;

	mutex_lock(&pcd->lock);

	list_for_each_entry_reverse(ce, &pcd->clock_list, node)
		clk_disable(ce->clk);

	mutex_unlock(&pcd->lock);

	return 0;
}

/**
 * pm_clk_resume - Enable clocks in a device's PM clock list.
 * @dev: Device to enable the clocks for.
 */
int pm_clk_resume(struct device *dev)
{
	struct pm_clk_data *pcd = __to_pcd(dev);
	struct pm_clock_entry *ce;

	dev_dbg(dev, "%s()\n", __func__);

	/* If there is no driver, the clocks should remain disabled. */
	if (!pcd || !dev->driver)
		return 0;

	mutex_lock(&pcd->lock);

	list_for_each_entry(ce, &pcd->clock_list, node)
		clk_enable(ce->clk);

	mutex_unlock(&pcd->lock);

	return 0;
}

#endif /* CONFIG_PM */

/**
 * enable_clock - Enable a device clock.
 * @dev: Device whose clock is to be enabled.
 * @con_id: Connection ID of the clock.
 */
static void enable_clock(struct device *dev, const char *con_id)
{
	struct clk *clk;

	clk = clk_get(dev, con_id);
	if (!IS_ERR(clk)) {
		clk_enable(clk);
		clk_put(clk);
		dev_info(dev, "Runtime PM disabled, clock forced on.\n");
	}
}

/**
 * disable_clock - Disable a device clock.
 * @dev: Device whose clock is to be disabled.
 * @con_id: Connection ID of the clock.
 */
static void disable_clock(struct device *dev, const char *con_id)
{
	struct clk *clk;

	clk = clk_get(dev, con_id);
	if (!IS_ERR(clk)) {
		clk_disable(clk);
		clk_put(clk);
		dev_info(dev, "Runtime PM disabled, clock forced off.\n");
	}
}

/**
 * pm_clk_notify - Notify routine for device addition and removal.
 * @nb: Notifier block object this function is a member of.
 * @action: Operation being carried out by the caller.
 * @data: Device the routine is being run for.
 *
 * For this function to work, @nb must be a member of an object of type
 * struct pm_clk_notifier_block containing all of the requisite data.
 * Specifically, the con_ids member of that object is used to enable or disable
 * the device's clocks, depending on @action.
 */
static int pm_clk_notify(struct notifier_block *nb,
				 unsigned long action, void *data)
{
	struct pm_clk_notifier_block *clknb;
	struct device *dev = data;
	char **con_id;

	dev_dbg(dev, "%s() %ld\n", __func__, action);

	clknb = container_of(nb, struct pm_clk_notifier_block, nb);

	switch (action) {
	case BUS_NOTIFY_BIND_DRIVER:
		if (clknb->con_ids[0]) {
			for (con_id = clknb->con_ids; *con_id; con_id++)
				enable_clock(dev, *con_id);
		} else {
			enable_clock(dev, NULL);
		}
		break;
	case BUS_NOTIFY_UNBOUND_DRIVER:
		if (clknb->con_ids[0]) {
			for (con_id = clknb->con_ids; *con_id; con_id++)
				disable_clock(dev, *con_id);
		} else {
			disable_clock(dev, NULL);
		}
		break;
	}

	return 0;
}

#endif /* !CONFIG_PM_RUNTIME */

/**
 * pm_clk_add_notifier - Add bus type notifier for power management clocks.
 * @bus: Bus type to add the notifier to.
 * @clknb: Notifier to be added to the given bus type.
 *
 * The nb member of @clknb is not expected to be initialized and its
 * notifier_call member will be replaced with pm_clk_notify().  However,
 * the remaining members of @clknb should be populated prior to calling this
 * routine.
 */
void pm_clk_add_notifier(struct bus_type *bus,
				 struct pm_clk_notifier_block *clknb)
{
	if (!bus || !clknb)
		return;

	clknb->nb.notifier_call = pm_clk_notify;
	bus_register_notifier(bus, &clknb->nb);
}