opp.c 28.3 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
/*
 * Generic OPP Interface
 *
 * Copyright (C) 2009-2010 Texas Instruments Incorporated.
 *	Nishanth Menon
 *	Romit Dasgupta
 *	Kevin Hilman
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/slab.h>
18
#include <linux/device.h>
19 20 21
#include <linux/list.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
22
#include <linux/pm_opp.h>
23
#include <linux/of.h>
24
#include <linux/export.h>
25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

/*
 * Internal data structure organization with the OPP layer library is as
 * follows:
 * dev_opp_list (root)
 *	|- device 1 (represents voltage domain 1)
 *	|	|- opp 1 (availability, freq, voltage)
 *	|	|- opp 2 ..
 *	...	...
 *	|	`- opp n ..
 *	|- device 2 (represents the next voltage domain)
 *	...
 *	`- device m (represents mth voltage domain)
 * device 1, 2.. are represented by dev_opp structure while each opp
 * is represented by the opp structure.
 */

/**
43
 * struct dev_pm_opp - Generic OPP description structure
44 45 46 47 48 49 50 51
 * @node:	opp list node. The nodes are maintained throughout the lifetime
 *		of boot. It is expected only an optimal set of OPPs are
 *		added to the library by the SoC framework.
 *		RCU usage: opp list is traversed with RCU locks. node
 *		modification is possible realtime, hence the modifications
 *		are protected by the dev_opp_list_lock for integrity.
 *		IMPORTANT: the opp nodes should be maintained in increasing
 *		order.
52
 * @dynamic:	not-created from static DT entries.
53 54 55 56
 * @available:	true/false - marks if this OPP as available or not
 * @rate:	Frequency in hertz
 * @u_volt:	Nominal voltage in microvolts corresponding to this OPP
 * @dev_opp:	points back to the device_opp struct this opp belongs to
57
 * @rcu_head:	RCU callback head used for deferred freeing
58 59 60
 *
 * This structure stores the OPP information for a given device.
 */
61
struct dev_pm_opp {
62 63 64
	struct list_head node;

	bool available;
65
	bool dynamic;
66 67 68 69
	unsigned long rate;
	unsigned long u_volt;

	struct device_opp *dev_opp;
70
	struct rcu_head rcu_head;
71 72 73 74 75 76 77 78 79 80
};

/**
 * struct device_opp - Device opp structure
 * @node:	list node - contains the devices with OPPs that
 *		have been registered. Nodes once added are not modified in this
 *		list.
 *		RCU usage: nodes are not modified in the list of device_opp,
 *		however addition is possible and is secured by dev_opp_list_lock
 * @dev:	device pointer
81
 * @srcu_head:	notifier head to notify the OPP availability changes.
82
 * @rcu_head:	RCU callback head used for deferred freeing
83 84 85 86
 * @opp_list:	list of opps
 *
 * This is an internal data structure maintaining the link to opps attached to
 * a device. This structure is not meant to be shared to users as it is
87 88 89 90 91
 * meant for book keeping and private to OPP library.
 *
 * Because the opp structures can be used from both rcu and srcu readers, we
 * need to wait for the grace period of both of them before freeing any
 * resources. And so we have used kfree_rcu() from within call_srcu() handlers.
92 93 94 95 96
 */
struct device_opp {
	struct list_head node;

	struct device *dev;
97
	struct srcu_notifier_head srcu_head;
98
	struct rcu_head rcu_head;
99 100 101 102 103 104 105 106 107 108 109 110
	struct list_head opp_list;
};

/*
 * The root of the list of all devices. All device_opp structures branch off
 * from here, with each device_opp containing the list of opp it supports in
 * various states of availability.
 */
static LIST_HEAD(dev_opp_list);
/* Lock to allow exclusive modification to the device and opp lists */
static DEFINE_MUTEX(dev_opp_list_lock);

111 112
#define opp_rcu_lockdep_assert()					\
do {									\
113 114
	RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&			\
				!lockdep_is_held(&dev_opp_list_lock),	\
115 116 117 118
			   "Missing rcu_read_lock() or "		\
			   "dev_opp_list_lock protection");		\
} while (0)

119
/**
120
 * _find_device_opp() - find device_opp struct using device pointer
121 122 123 124 125
 * @dev:	device pointer used to lookup device OPPs
 *
 * Search list of device OPPs for one containing matching device. Does a RCU
 * reader operation to grab the pointer needed.
 *
126
 * Return: pointer to 'struct device_opp' if found, otherwise -ENODEV or
127 128 129 130 131 132
 * -EINVAL based on type of error.
 *
 * Locking: This function must be called under rcu_read_lock(). device_opp
 * is a RCU protected pointer. This means that device_opp is valid as long
 * as we are under RCU lock.
 */
133
static struct device_opp *_find_device_opp(struct device *dev)
134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152
{
	struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV);

	if (unlikely(IS_ERR_OR_NULL(dev))) {
		pr_err("%s: Invalid parameters\n", __func__);
		return ERR_PTR(-EINVAL);
	}

	list_for_each_entry_rcu(tmp_dev_opp, &dev_opp_list, node) {
		if (tmp_dev_opp->dev == dev) {
			dev_opp = tmp_dev_opp;
			break;
		}
	}

	return dev_opp;
}

/**
153
 * dev_pm_opp_get_voltage() - Gets the voltage corresponding to an available opp
154 155
 * @opp:	opp for which voltage has to be returned for
 *
156
 * Return: voltage in micro volt corresponding to the opp, else
157 158 159 160 161 162 163 164 165 166
 * return 0
 *
 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
 * protected pointer. This means that opp which could have been fetched by
 * opp_find_freq_{exact,ceil,floor} functions is valid as long as we are
 * under RCU lock. The pointer returned by the opp_find_freq family must be
 * used in the same section as the usage of this function with the pointer
 * prior to unlocking with rcu_read_unlock() to maintain the integrity of the
 * pointer.
 */
167
unsigned long dev_pm_opp_get_voltage(struct dev_pm_opp *opp)
168
{
169
	struct dev_pm_opp *tmp_opp;
170 171
	unsigned long v = 0;

172 173
	opp_rcu_lockdep_assert();

174 175 176 177 178 179 180 181
	tmp_opp = rcu_dereference(opp);
	if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available)
		pr_err("%s: Invalid parameters\n", __func__);
	else
		v = tmp_opp->u_volt;

	return v;
}
182
EXPORT_SYMBOL_GPL(dev_pm_opp_get_voltage);
183 184

/**
185
 * dev_pm_opp_get_freq() - Gets the frequency corresponding to an available opp
186 187
 * @opp:	opp for which frequency has to be returned for
 *
188
 * Return: frequency in hertz corresponding to the opp, else
189 190 191 192 193 194 195 196 197 198
 * return 0
 *
 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
 * protected pointer. This means that opp which could have been fetched by
 * opp_find_freq_{exact,ceil,floor} functions is valid as long as we are
 * under RCU lock. The pointer returned by the opp_find_freq family must be
 * used in the same section as the usage of this function with the pointer
 * prior to unlocking with rcu_read_unlock() to maintain the integrity of the
 * pointer.
 */
199
unsigned long dev_pm_opp_get_freq(struct dev_pm_opp *opp)
200
{
201
	struct dev_pm_opp *tmp_opp;
202 203
	unsigned long f = 0;

204 205
	opp_rcu_lockdep_assert();

206 207 208 209 210 211 212 213
	tmp_opp = rcu_dereference(opp);
	if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available)
		pr_err("%s: Invalid parameters\n", __func__);
	else
		f = tmp_opp->rate;

	return f;
}
214
EXPORT_SYMBOL_GPL(dev_pm_opp_get_freq);
215 216

/**
217
 * dev_pm_opp_get_opp_count() - Get number of opps available in the opp list
218 219
 * @dev:	device for which we do this operation
 *
220
 * Return: This function returns the number of available opps if there are any,
221 222
 * else returns 0 if none or the corresponding error value.
 *
223
 * Locking: This function takes rcu_read_lock().
224
 */
225
int dev_pm_opp_get_opp_count(struct device *dev)
226 227
{
	struct device_opp *dev_opp;
228
	struct dev_pm_opp *temp_opp;
229 230
	int count = 0;

231
	rcu_read_lock();
232

233
	dev_opp = _find_device_opp(dev);
234
	if (IS_ERR(dev_opp)) {
235 236 237 238
		count = PTR_ERR(dev_opp);
		dev_err(dev, "%s: device OPP not found (%d)\n",
			__func__, count);
		goto out_unlock;
239 240 241 242 243 244 245
	}

	list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
		if (temp_opp->available)
			count++;
	}

246 247
out_unlock:
	rcu_read_unlock();
248 249
	return count;
}
250
EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_count);
251 252

/**
253
 * dev_pm_opp_find_freq_exact() - search for an exact frequency
254 255
 * @dev:		device for which we do this operation
 * @freq:		frequency to search for
256
 * @available:		true/false - match for available opp
257
 *
258 259 260
 * Return: Searches for exact match in the opp list and returns pointer to the
 * matching opp if found, else returns ERR_PTR in case of error and should
 * be handled using IS_ERR. Error return values can be:
261 262 263
 * EINVAL:	for bad pointer
 * ERANGE:	no match found for search
 * ENODEV:	if device not found in list of registered devices
264 265 266 267 268 269 270 271 272 273 274 275 276 277
 *
 * Note: available is a modifier for the search. if available=true, then the
 * match is for exact matching frequency and is available in the stored OPP
 * table. if false, the match is for exact frequency which is not available.
 *
 * This provides a mechanism to enable an opp which is not available currently
 * or the opposite as well.
 *
 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
 * protected pointer. The reason for the same is that the opp pointer which is
 * returned will remain valid for use with opp_get_{voltage, freq} only while
 * under the locked area. The pointer returned must be used prior to unlocking
 * with rcu_read_unlock() to maintain the integrity of the pointer.
 */
278 279 280
struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
					      unsigned long freq,
					      bool available)
281 282
{
	struct device_opp *dev_opp;
283
	struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
284

285 286
	opp_rcu_lockdep_assert();

287
	dev_opp = _find_device_opp(dev);
288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303
	if (IS_ERR(dev_opp)) {
		int r = PTR_ERR(dev_opp);
		dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r);
		return ERR_PTR(r);
	}

	list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
		if (temp_opp->available == available &&
				temp_opp->rate == freq) {
			opp = temp_opp;
			break;
		}
	}

	return opp;
}
304
EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_exact);
305 306

/**
307
 * dev_pm_opp_find_freq_ceil() - Search for an rounded ceil freq
308 309 310 311 312 313
 * @dev:	device for which we do this operation
 * @freq:	Start frequency
 *
 * Search for the matching ceil *available* OPP from a starting freq
 * for a device.
 *
314
 * Return: matching *opp and refreshes *freq accordingly, else returns
315 316 317 318 319
 * ERR_PTR in case of error and should be handled using IS_ERR. Error return
 * values can be:
 * EINVAL:	for bad pointer
 * ERANGE:	no match found for search
 * ENODEV:	if device not found in list of registered devices
320 321 322 323 324 325 326
 *
 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
 * protected pointer. The reason for the same is that the opp pointer which is
 * returned will remain valid for use with opp_get_{voltage, freq} only while
 * under the locked area. The pointer returned must be used prior to unlocking
 * with rcu_read_unlock() to maintain the integrity of the pointer.
 */
327 328
struct dev_pm_opp *dev_pm_opp_find_freq_ceil(struct device *dev,
					     unsigned long *freq)
329 330
{
	struct device_opp *dev_opp;
331
	struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
332

333 334
	opp_rcu_lockdep_assert();

335 336 337 338 339
	if (!dev || !freq) {
		dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq);
		return ERR_PTR(-EINVAL);
	}

340
	dev_opp = _find_device_opp(dev);
341
	if (IS_ERR(dev_opp))
342
		return ERR_CAST(dev_opp);
343 344 345 346 347 348 349 350 351 352 353

	list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
		if (temp_opp->available && temp_opp->rate >= *freq) {
			opp = temp_opp;
			*freq = opp->rate;
			break;
		}
	}

	return opp;
}
354
EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_ceil);
355 356

/**
357
 * dev_pm_opp_find_freq_floor() - Search for a rounded floor freq
358 359 360 361 362 363
 * @dev:	device for which we do this operation
 * @freq:	Start frequency
 *
 * Search for the matching floor *available* OPP from a starting freq
 * for a device.
 *
364
 * Return: matching *opp and refreshes *freq accordingly, else returns
365 366 367 368 369
 * ERR_PTR in case of error and should be handled using IS_ERR. Error return
 * values can be:
 * EINVAL:	for bad pointer
 * ERANGE:	no match found for search
 * ENODEV:	if device not found in list of registered devices
370 371 372 373 374 375 376
 *
 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
 * protected pointer. The reason for the same is that the opp pointer which is
 * returned will remain valid for use with opp_get_{voltage, freq} only while
 * under the locked area. The pointer returned must be used prior to unlocking
 * with rcu_read_unlock() to maintain the integrity of the pointer.
 */
377 378
struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev,
					      unsigned long *freq)
379 380
{
	struct device_opp *dev_opp;
381
	struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
382

383 384
	opp_rcu_lockdep_assert();

385 386 387 388 389
	if (!dev || !freq) {
		dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq);
		return ERR_PTR(-EINVAL);
	}

390
	dev_opp = _find_device_opp(dev);
391
	if (IS_ERR(dev_opp))
392
		return ERR_CAST(dev_opp);
393 394 395 396 397 398 399 400 401 402 403 404 405 406 407

	list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
		if (temp_opp->available) {
			/* go to the next node, before choosing prev */
			if (temp_opp->rate > *freq)
				break;
			else
				opp = temp_opp;
		}
	}
	if (!IS_ERR(opp))
		*freq = opp->rate;

	return opp;
}
408
EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor);
409

410 411 412 413 414 415 416 417 418
/**
 * _add_device_opp() - Allocate a new device OPP table
 * @dev:	device for which we do this operation
 *
 * New device node which uses OPPs - used when multiple devices with OPP tables
 * are maintained.
 *
 * Return: valid device_opp pointer if success, else NULL.
 */
419
static struct device_opp *_add_device_opp(struct device *dev)
420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439
{
	struct device_opp *dev_opp;

	/*
	 * Allocate a new device OPP table. In the infrequent case where a new
	 * device is needed to be added, we pay this penalty.
	 */
	dev_opp = kzalloc(sizeof(*dev_opp), GFP_KERNEL);
	if (!dev_opp)
		return NULL;

	dev_opp->dev = dev;
	srcu_init_notifier_head(&dev_opp->srcu_head);
	INIT_LIST_HEAD(&dev_opp->opp_list);

	/* Secure the device list modification */
	list_add_rcu(&dev_opp->node, &dev_opp_list);
	return dev_opp;
}

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
/**
 * _opp_add_dynamic() - Allocate a dynamic OPP.
 * @dev:	device for which we do this operation
 * @freq:	Frequency in Hz for this OPP
 * @u_volt:	Voltage in uVolts for this OPP
 * @dynamic:	Dynamically added OPPs.
 *
 * This function adds an opp definition to the opp list and returns status.
 * The opp is made available by default and it can be controlled using
 * dev_pm_opp_enable/disable functions and may be removed by dev_pm_opp_remove.
 *
 * NOTE: "dynamic" parameter impacts OPPs added by the of_init_opp_table and
 * freed by of_free_opp_table.
 *
 * Locking: The internal device_opp and opp structures are RCU protected.
 * Hence this function internally uses RCU updater strategy with mutex locks
 * to keep the integrity of the internal data structures. Callers should ensure
 * that this function is *NOT* called under RCU protection or in contexts where
 * mutex cannot be locked.
 *
 * Return:
 * 0		On success OR
 *		Duplicate OPPs (both freq and volt are same) and opp->available
 * -EEXIST	Freq are same and volt are different OR
 *		Duplicate OPPs (both freq and volt are same) and !opp->available
 * -ENOMEM	Memory allocation failure
 */
467 468
static int _opp_add_dynamic(struct device *dev, unsigned long freq,
			    long u_volt, bool dynamic)
469 470
{
	struct device_opp *dev_opp = NULL;
471
	struct dev_pm_opp *opp, *new_opp;
472
	struct list_head *head;
473
	int ret;
474 475

	/* allocate new OPP node */
476
	new_opp = kzalloc(sizeof(*new_opp), GFP_KERNEL);
477
	if (!new_opp)
478 479 480 481 482
		return -ENOMEM;

	/* Hold our list modification lock here */
	mutex_lock(&dev_opp_list_lock);

483 484 485 486
	/* populate the opp table */
	new_opp->rate = freq;
	new_opp->u_volt = u_volt;
	new_opp->available = true;
487
	new_opp->dynamic = dynamic;
488

489
	/* Check for existing list for 'dev' */
490
	dev_opp = _find_device_opp(dev);
491
	if (IS_ERR(dev_opp)) {
492
		dev_opp = _add_device_opp(dev);
493
		if (!dev_opp) {
494 495
			ret = -ENOMEM;
			goto free_opp;
496 497
		}

498 499
		head = &dev_opp->opp_list;
		goto list_add;
500 501
	}

502 503 504 505
	/*
	 * Insert new OPP in order of increasing frequency
	 * and discard if already present
	 */
506 507
	head = &dev_opp->opp_list;
	list_for_each_entry_rcu(opp, &dev_opp->opp_list, node) {
508
		if (new_opp->rate <= opp->rate)
509 510 511 512 513
			break;
		else
			head = &opp->node;
	}

514 515
	/* Duplicate OPPs ? */
	if (new_opp->rate == opp->rate) {
516
		ret = opp->available && new_opp->u_volt == opp->u_volt ?
517 518 519 520 521
			0 : -EEXIST;

		dev_warn(dev, "%s: duplicate OPPs detected. Existing: freq: %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n",
			 __func__, opp->rate, opp->u_volt, opp->available,
			 new_opp->rate, new_opp->u_volt, new_opp->available);
522
		goto free_opp;
523 524
	}

525
list_add:
526
	new_opp->dev_opp = dev_opp;
527 528 529
	list_add_rcu(&new_opp->node, head);
	mutex_unlock(&dev_opp_list_lock);

530 531 532 533
	/*
	 * Notify the changes in the availability of the operable
	 * frequency/voltage list.
	 */
534
	srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_ADD, new_opp);
535
	return 0;
536 537 538 539 540

free_opp:
	mutex_unlock(&dev_opp_list_lock);
	kfree(new_opp);
	return ret;
541
}
542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559

/**
 * dev_pm_opp_add()  - Add an OPP table from a table definitions
 * @dev:	device for which we do this operation
 * @freq:	Frequency in Hz for this OPP
 * @u_volt:	Voltage in uVolts for this OPP
 *
 * This function adds an opp definition to the opp list and returns status.
 * The opp is made available by default and it can be controlled using
 * dev_pm_opp_enable/disable functions.
 *
 * Locking: The internal device_opp and opp structures are RCU protected.
 * Hence this function internally uses RCU updater strategy with mutex locks
 * to keep the integrity of the internal data structures. Callers should ensure
 * that this function is *NOT* called under RCU protection or in contexts where
 * mutex cannot be locked.
 *
 * Return:
560
 * 0		On success OR
561
 *		Duplicate OPPs (both freq and volt are same) and opp->available
562
 * -EEXIST	Freq are same and volt are different OR
563
 *		Duplicate OPPs (both freq and volt are same) and !opp->available
564
 * -ENOMEM	Memory allocation failure
565 566 567
 */
int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
{
568
	return _opp_add_dynamic(dev, freq, u_volt, true);
569
}
570
EXPORT_SYMBOL_GPL(dev_pm_opp_add);
571

572 573 574 575
/**
 * _kfree_opp_rcu() - Free OPP RCU handler
 * @head:	RCU head
 */
576
static void _kfree_opp_rcu(struct rcu_head *head)
577 578 579 580 581 582
{
	struct dev_pm_opp *opp = container_of(head, struct dev_pm_opp, rcu_head);

	kfree_rcu(opp, rcu_head);
}

583 584 585 586
/**
 * _kfree_device_rcu() - Free device_opp RCU handler
 * @head:	RCU head
 */
587
static void _kfree_device_rcu(struct rcu_head *head)
588 589 590
{
	struct device_opp *device_opp = container_of(head, struct device_opp, rcu_head);

591
	kfree_rcu(device_opp, rcu_head);
592 593
}

594 595 596 597 598 599 600 601 602 603 604
/**
 * _opp_remove()  - Remove an OPP from a table definition
 * @dev_opp:	points back to the device_opp struct this opp belongs to
 * @opp:	pointer to the OPP to remove
 *
 * This function removes an opp definition from the opp list.
 *
 * Locking: The internal device_opp and opp structures are RCU protected.
 * It is assumed that the caller holds required mutex for an RCU updater
 * strategy.
 */
605 606
static void _opp_remove(struct device_opp *dev_opp,
			struct dev_pm_opp *opp)
607 608 609 610 611 612 613
{
	/*
	 * Notify the changes in the availability of the operable
	 * frequency/voltage list.
	 */
	srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_REMOVE, opp);
	list_del_rcu(&opp->node);
614
	call_srcu(&dev_opp->srcu_head.srcu, &opp->rcu_head, _kfree_opp_rcu);
615 616 617 618

	if (list_empty(&dev_opp->opp_list)) {
		list_del_rcu(&dev_opp->node);
		call_srcu(&dev_opp->srcu_head.srcu, &dev_opp->rcu_head,
619
			  _kfree_device_rcu);
620 621 622 623 624 625 626 627 628
	}
}

/**
 * dev_pm_opp_remove()  - Remove an OPP from OPP list
 * @dev:	device for which we do this operation
 * @freq:	OPP to remove with matching 'freq'
 *
 * This function removes an opp from the opp list.
629 630 631 632 633 634
 *
 * Locking: The internal device_opp and opp structures are RCU protected.
 * Hence this function internally uses RCU updater strategy with mutex locks
 * to keep the integrity of the internal data structures. Callers should ensure
 * that this function is *NOT* called under RCU protection or in contexts where
 * mutex cannot be locked.
635 636 637 638 639 640 641 642 643 644
 */
void dev_pm_opp_remove(struct device *dev, unsigned long freq)
{
	struct dev_pm_opp *opp;
	struct device_opp *dev_opp;
	bool found = false;

	/* Hold our list modification lock here */
	mutex_lock(&dev_opp_list_lock);

645
	dev_opp = _find_device_opp(dev);
646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661
	if (IS_ERR(dev_opp))
		goto unlock;

	list_for_each_entry(opp, &dev_opp->opp_list, node) {
		if (opp->rate == freq) {
			found = true;
			break;
		}
	}

	if (!found) {
		dev_warn(dev, "%s: Couldn't find OPP with freq: %lu\n",
			 __func__, freq);
		goto unlock;
	}

662
	_opp_remove(dev_opp, opp);
663 664 665 666 667
unlock:
	mutex_unlock(&dev_opp_list_lock);
}
EXPORT_SYMBOL_GPL(dev_pm_opp_remove);

668
/**
669
 * _opp_set_availability() - helper to set the availability of an opp
670 671 672 673 674 675 676
 * @dev:		device for which we do this operation
 * @freq:		OPP frequency to modify availability
 * @availability_req:	availability status requested for this opp
 *
 * Set the availability of an OPP with an RCU operation, opp_{enable,disable}
 * share a common logic which is isolated here.
 *
677
 * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
678 679 680 681 682 683 684 685 686
 * copy operation, returns 0 if no modifcation was done OR modification was
 * successful.
 *
 * Locking: The internal device_opp and opp structures are RCU protected.
 * Hence this function internally uses RCU updater strategy with mutex locks to
 * keep the integrity of the internal data structures. Callers should ensure
 * that this function is *NOT* called under RCU protection or in contexts where
 * mutex locking or synchronize_rcu() blocking calls cannot be used.
 */
687 688
static int _opp_set_availability(struct device *dev, unsigned long freq,
				 bool availability_req)
689
{
690
	struct device_opp *dev_opp;
691
	struct dev_pm_opp *new_opp, *tmp_opp, *opp = ERR_PTR(-ENODEV);
692 693 694
	int r = 0;

	/* keep the node allocated */
695
	new_opp = kmalloc(sizeof(*new_opp), GFP_KERNEL);
696
	if (!new_opp)
697 698 699 700 701
		return -ENOMEM;

	mutex_lock(&dev_opp_list_lock);

	/* Find the device_opp */
702
	dev_opp = _find_device_opp(dev);
703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731
	if (IS_ERR(dev_opp)) {
		r = PTR_ERR(dev_opp);
		dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r);
		goto unlock;
	}

	/* Do we have the frequency? */
	list_for_each_entry(tmp_opp, &dev_opp->opp_list, node) {
		if (tmp_opp->rate == freq) {
			opp = tmp_opp;
			break;
		}
	}
	if (IS_ERR(opp)) {
		r = PTR_ERR(opp);
		goto unlock;
	}

	/* Is update really needed? */
	if (opp->available == availability_req)
		goto unlock;
	/* copy the old data over */
	*new_opp = *opp;

	/* plug in new node */
	new_opp->available = availability_req;

	list_replace_rcu(&opp->node, &new_opp->node);
	mutex_unlock(&dev_opp_list_lock);
732
	call_srcu(&dev_opp->srcu_head.srcu, &opp->rcu_head, _kfree_opp_rcu);
733

734 735
	/* Notify the change of the OPP availability */
	if (availability_req)
736
		srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_ENABLE,
737 738
					 new_opp);
	else
739
		srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_DISABLE,
740 741
					 new_opp);

V
Vincent Guittot 已提交
742
	return 0;
743 744 745 746 747 748 749 750

unlock:
	mutex_unlock(&dev_opp_list_lock);
	kfree(new_opp);
	return r;
}

/**
751
 * dev_pm_opp_enable() - Enable a specific OPP
752 753 754 755 756
 * @dev:	device for which we do this operation
 * @freq:	OPP frequency to enable
 *
 * Enables a provided opp. If the operation is valid, this returns 0, else the
 * corresponding error value. It is meant to be used for users an OPP available
757
 * after being temporarily made unavailable with dev_pm_opp_disable.
758 759 760 761 762 763
 *
 * Locking: The internal device_opp and opp structures are RCU protected.
 * Hence this function indirectly uses RCU and mutex locks to keep the
 * integrity of the internal data structures. Callers should ensure that
 * this function is *NOT* called under RCU protection or in contexts where
 * mutex locking or synchronize_rcu() blocking calls cannot be used.
764 765 766 767
 *
 * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
 * copy operation, returns 0 if no modifcation was done OR modification was
 * successful.
768
 */
769
int dev_pm_opp_enable(struct device *dev, unsigned long freq)
770
{
771
	return _opp_set_availability(dev, freq, true);
772
}
773
EXPORT_SYMBOL_GPL(dev_pm_opp_enable);
774 775

/**
776
 * dev_pm_opp_disable() - Disable a specific OPP
777 778 779 780 781 782
 * @dev:	device for which we do this operation
 * @freq:	OPP frequency to disable
 *
 * Disables a provided opp. If the operation is valid, this returns
 * 0, else the corresponding error value. It is meant to be a temporary
 * control by users to make this OPP not available until the circumstances are
783
 * right to make it available again (with a call to dev_pm_opp_enable).
784 785 786 787 788 789
 *
 * Locking: The internal device_opp and opp structures are RCU protected.
 * Hence this function indirectly uses RCU and mutex locks to keep the
 * integrity of the internal data structures. Callers should ensure that
 * this function is *NOT* called under RCU protection or in contexts where
 * mutex locking or synchronize_rcu() blocking calls cannot be used.
790 791 792 793
 *
 * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
 * copy operation, returns 0 if no modifcation was done OR modification was
 * successful.
794
 */
795
int dev_pm_opp_disable(struct device *dev, unsigned long freq)
796
{
797
	return _opp_set_availability(dev, freq, false);
798
}
799
EXPORT_SYMBOL_GPL(dev_pm_opp_disable);
800

801
/**
802
 * dev_pm_opp_get_notifier() - find notifier_head of the device with opp
803
 * @dev:	device pointer used to lookup device OPPs.
804 805 806 807 808 809 810 811 812 813
 *
 * Return: pointer to  notifier head if found, otherwise -ENODEV or
 * -EINVAL based on type of error casted as pointer. value must be checked
 *  with IS_ERR to determine valid pointer or error result.
 *
 * Locking: This function must be called under rcu_read_lock(). dev_opp is a RCU
 * protected pointer. The reason for the same is that the opp pointer which is
 * returned will remain valid for use with opp_get_{voltage, freq} only while
 * under the locked area. The pointer returned must be used prior to unlocking
 * with rcu_read_unlock() to maintain the integrity of the pointer.
814
 */
815
struct srcu_notifier_head *dev_pm_opp_get_notifier(struct device *dev)
816
{
817
	struct device_opp *dev_opp = _find_device_opp(dev);
818 819

	if (IS_ERR(dev_opp))
820
		return ERR_CAST(dev_opp); /* matching type */
821

822
	return &dev_opp->srcu_head;
823
}
824
EXPORT_SYMBOL_GPL(dev_pm_opp_get_notifier);
825 826 827 828 829 830 831

#ifdef CONFIG_OF
/**
 * of_init_opp_table() - Initialize opp table from device tree
 * @dev:	device pointer used to lookup device OPPs.
 *
 * Register the initial OPP table with the OPP library for given device.
832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847
 *
 * Locking: The internal device_opp and opp structures are RCU protected.
 * Hence this function indirectly uses RCU updater strategy with mutex locks
 * to keep the integrity of the internal data structures. Callers should ensure
 * that this function is *NOT* called under RCU protection or in contexts where
 * mutex cannot be locked.
 *
 * Return:
 * 0		On success OR
 *		Duplicate OPPs (both freq and volt are same) and opp->available
 * -EEXIST	Freq are same and volt are different OR
 *		Duplicate OPPs (both freq and volt are same) and !opp->available
 * -ENOMEM	Memory allocation failure
 * -ENODEV	when 'operating-points' property is not found or is invalid data
 *		in device node.
 * -ENODATA	when empty 'operating-points' property is found
848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875
 */
int of_init_opp_table(struct device *dev)
{
	const struct property *prop;
	const __be32 *val;
	int nr;

	prop = of_find_property(dev->of_node, "operating-points", NULL);
	if (!prop)
		return -ENODEV;
	if (!prop->value)
		return -ENODATA;

	/*
	 * Each OPP is a set of tuples consisting of frequency and
	 * voltage like <freq-kHz vol-uV>.
	 */
	nr = prop->length / sizeof(u32);
	if (nr % 2) {
		dev_err(dev, "%s: Invalid OPP list\n", __func__);
		return -EINVAL;
	}

	val = prop->value;
	while (nr) {
		unsigned long freq = be32_to_cpup(val++) * 1000;
		unsigned long volt = be32_to_cpup(val++);

876
		if (_opp_add_dynamic(dev, freq, volt, false))
877 878 879 880 881 882 883
			dev_warn(dev, "%s: Failed to add OPP %ld\n",
				 __func__, freq);
		nr -= 2;
	}

	return 0;
}
884
EXPORT_SYMBOL_GPL(of_init_opp_table);
885 886 887 888 889 890

/**
 * of_free_opp_table() - Free OPP table entries created from static DT entries
 * @dev:	device pointer used to lookup device OPPs.
 *
 * Free OPPs created using static entries present in DT.
891 892 893 894 895 896
 *
 * Locking: The internal device_opp and opp structures are RCU protected.
 * Hence this function indirectly uses RCU updater strategy with mutex locks
 * to keep the integrity of the internal data structures. Callers should ensure
 * that this function is *NOT* called under RCU protection or in contexts where
 * mutex cannot be locked.
897 898 899
 */
void of_free_opp_table(struct device *dev)
{
900
	struct device_opp *dev_opp;
901 902 903
	struct dev_pm_opp *opp, *tmp;

	/* Check for existing list for 'dev' */
904
	dev_opp = _find_device_opp(dev);
905 906 907 908 909 910 911
	if (IS_ERR(dev_opp)) {
		int error = PTR_ERR(dev_opp);
		if (error != -ENODEV)
			WARN(1, "%s: dev_opp: %d\n",
			     IS_ERR_OR_NULL(dev) ?
					"Invalid device" : dev_name(dev),
			     error);
912
		return;
913
	}
914 915 916 917 918 919 920

	/* Hold our list modification lock here */
	mutex_lock(&dev_opp_list_lock);

	/* Free static OPPs */
	list_for_each_entry_safe(opp, tmp, &dev_opp->opp_list, node) {
		if (!opp->dynamic)
921
			_opp_remove(dev_opp, opp);
922 923 924 925 926
	}

	mutex_unlock(&dev_opp_list_lock);
}
EXPORT_SYMBOL_GPL(of_free_opp_table);
927
#endif