gpiolib.c 53.4 KB
Newer Older
1 2
#include <linux/kernel.h>
#include <linux/module.h>
3
#include <linux/interrupt.h>
4 5
#include <linux/irq.h>
#include <linux/spinlock.h>
6
#include <linux/list.h>
David Brownell's avatar
David Brownell committed
7 8 9 10 11
#include <linux/device.h>
#include <linux/err.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/gpio.h>
12
#include <linux/of_gpio.h>
13
#include <linux/idr.h>
14
#include <linux/slab.h>
15

16 17
#define CREATE_TRACE_POINTS
#include <trace/events/gpio.h>
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

/* Optional implementation infrastructure for GPIO interfaces.
 *
 * Platforms may want to use this if they tend to use very many GPIOs
 * that aren't part of a System-On-Chip core; or across I2C/SPI/etc.
 *
 * When kernel footprint or instruction count is an issue, simpler
 * implementations may be preferred.  The GPIO programming interface
 * allows for inlining speed-critical get/set operations for common
 * cases, so that access to SOC-integrated GPIOs can sometimes cost
 * only an instruction or two per bit.
 */


/* When debugging, extend minimal trust to callers and platform code.
 * Also emit diagnostic messages that may help initial bringup, when
 * board setup or driver bugs are most common.
 *
 * Otherwise, minimize overhead in what may be bitbanging codepaths.
 */
#ifdef	DEBUG
#define	extra_checks	1
#else
#define	extra_checks	0
#endif

/* gpio_lock prevents conflicts during gpio_desc[] table updates.
 * While any GPIO is requested, its gpio_chip is not removable;
 * each GPIO's "requested" flag serves as a lock and refcount.
 */
static DEFINE_SPINLOCK(gpio_lock);

struct gpio_desc {
	struct gpio_chip	*chip;
	unsigned long		flags;
/* flag symbols are bit numbers */
#define FLAG_REQUESTED	0
#define FLAG_IS_OUT	1
56 57 58 59 60 61 62
#define FLAG_EXPORT	2	/* protected by sysfs_lock */
#define FLAG_SYSFS	3	/* exported via /sys/class/gpio/control */
#define FLAG_TRIG_FALL	4	/* trigger on falling edge */
#define FLAG_TRIG_RISE	5	/* trigger on rising edge */
#define FLAG_ACTIVE_LOW	6	/* sysfs value has active low */
#define FLAG_OPEN_DRAIN	7	/* Gpio is open drain type */
#define FLAG_OPEN_SOURCE 8	/* Gpio is open source type */
63

64
#define ID_SHIFT	16	/* add new flags before this one */
65

66
#define GPIO_FLAGS_MASK		((1 << ID_SHIFT) - 1)
67
#define GPIO_TRIGGER_MASK	(BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE))
68 69 70 71 72 73 74

#ifdef CONFIG_DEBUG_FS
	const char		*label;
#endif
};
static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];

75 76
#define GPIO_OFFSET_VALID(chip, offset) (offset >= 0 && offset < chip->ngpio)

77 78
static LIST_HEAD(gpio_chips);

79
#ifdef CONFIG_GPIO_SYSFS
80
static DEFINE_IDR(dirent_idr);
81 82
#endif

83 84 85 86 87 88 89 90
/*
 * Internal gpiod_* API using descriptors instead of the integer namespace.
 * Most of this should eventually go public.
 */
static int gpiod_request(struct gpio_desc *desc, const char *label);
static void gpiod_free(struct gpio_desc *desc);
static int gpiod_direction_input(struct gpio_desc *desc);
static int gpiod_direction_output(struct gpio_desc *desc, int value);
91
static int gpiod_get_direction(const struct gpio_desc *desc);
92
static int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce);
93
static int gpiod_get_value_cansleep(const struct gpio_desc *desc);
94
static void gpiod_set_value_cansleep(struct gpio_desc *desc, int value);
95
static int gpiod_get_value(const struct gpio_desc *desc);
96
static void gpiod_set_value(struct gpio_desc *desc, int value);
97 98
static int gpiod_cansleep(const struct gpio_desc *desc);
static int gpiod_to_irq(const struct gpio_desc *desc);
99 100 101 102 103 104 105
static int gpiod_export(struct gpio_desc *desc, bool direction_may_change);
static int gpiod_export_link(struct device *dev, const char *name,
			     struct gpio_desc *desc);
static int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value);
static void gpiod_unexport(struct gpio_desc *desc);


106 107 108 109 110 111 112
static inline void desc_set_label(struct gpio_desc *d, const char *label)
{
#ifdef CONFIG_DEBUG_FS
	d->label = label;
#endif
}

113 114 115 116 117
/*
 * Return the GPIO number of the passed descriptor relative to its chip
 */
static int gpio_chip_hwgpio(const struct gpio_desc *desc)
{
118
	return desc - &desc->chip->desc[0];
119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138
}

/**
 * Convert a GPIO number to its descriptor
 */
static struct gpio_desc *gpio_to_desc(unsigned gpio)
{
	if (WARN(!gpio_is_valid(gpio), "invalid GPIO %d\n", gpio))
		return NULL;
	else
		return &gpio_desc[gpio];
}

/**
 * Convert a GPIO descriptor to the integer namespace.
 * This should disappear in the future but is needed since we still
 * use GPIO numbers for error messages and sysfs nodes
 */
static int desc_to_gpio(const struct gpio_desc *desc)
{
139
	return desc->chip->base + gpio_chip_hwgpio(desc);
140 141 142
}


143 144 145 146
/* Warn when drivers omit gpio_request() calls -- legal but ill-advised
 * when setting direction, and otherwise illegal.  Until board setup code
 * and drivers use explicit requests everywhere (which won't happen when
 * those calls have no teeth) we can't avoid autorequesting.  This nag
David Brownell's avatar
David Brownell committed
147 148
 * message should motivate switching to explicit requests... so should
 * the weaker cleanup after faults, compared to gpio_request().
149 150 151 152
 *
 * NOTE: the autorequest mechanism is going away; at this point it's
 * only "legal" in the sense that (old) code using it won't break yet,
 * but instead only triggers a WARN() stack dump.
153
 */
154
static int gpio_ensure_requested(struct gpio_desc *desc)
155
{
156
	const struct gpio_chip *chip = desc->chip;
157
	const int gpio = desc_to_gpio(desc);
David Brownell's avatar
David Brownell committed
158

159 160
	if (WARN(test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0,
			"autorequest GPIO-%d\n", gpio)) {
David Brownell's avatar
David Brownell committed
161 162 163 164 165 166
		if (!try_module_get(chip->owner)) {
			pr_err("GPIO-%d: module can't be gotten \n", gpio);
			clear_bit(FLAG_REQUESTED, &desc->flags);
			/* lose */
			return -EIO;
		}
167
		desc_set_label(desc, "[auto]");
David Brownell's avatar
David Brownell committed
168 169 170
		/* caller must chip->request() w/o spinlock */
		if (chip->request)
			return 1;
171
	}
David Brownell's avatar
David Brownell committed
172
	return 0;
173 174
}

175
static struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
176
{
177
	return desc ? desc->chip : NULL;
178 179
}

180
/* caller holds gpio_lock *OR* gpio is marked as requested */
181
struct gpio_chip *gpio_to_chip(unsigned gpio)
182
{
183
	return gpiod_to_chip(gpio_to_desc(gpio));
184 185
}

186 187 188
/* dynamic allocation of GPIOs, e.g. on a hotplugged device */
static int gpiochip_find_base(int ngpio)
{
189 190
	struct gpio_chip *chip;
	int base = ARCH_NR_GPIOS - ngpio;
191

192 193 194 195 196 197 198
	list_for_each_entry_reverse(chip, &gpio_chips, list) {
		/* found a free space? */
		if (chip->base + chip->ngpio <= base)
			break;
		else
			/* nope, check the space right before the chip */
			base = chip->base - ngpio;
199 200
	}

201
	if (gpio_is_valid(base)) {
202
		pr_debug("%s: found new base at %d\n", __func__, base);
203 204 205 206
		return base;
	} else {
		pr_err("%s: cannot find free range\n", __func__);
		return -ENOSPC;
Anton Vorontsov's avatar
Anton Vorontsov committed
207 208 209
	}
}

210
/* caller ensures gpio is valid and requested, chip->get_direction may sleep  */
211
static int gpiod_get_direction(const struct gpio_desc *desc)
212 213
{
	struct gpio_chip	*chip;
214
	unsigned		offset;
215 216
	int			status = -EINVAL;

217 218
	chip = gpiod_to_chip(desc);
	offset = gpio_chip_hwgpio(desc);
219 220 221 222

	if (!chip->get_direction)
		return status;

223
	status = chip->get_direction(chip, offset);
224 225 226
	if (status > 0) {
		/* GPIOF_DIR_IN, or other positive */
		status = 1;
227 228 229
		/* FLAG_IS_OUT is just a cache of the result of get_direction(),
		 * so it does not affect constness per se */
		clear_bit(FLAG_IS_OUT, &((struct gpio_desc *)desc)->flags);
230 231 232
	}
	if (status == 0) {
		/* GPIOF_DIR_OUT */
233
		set_bit(FLAG_IS_OUT, &((struct gpio_desc *)desc)->flags);
234 235 236 237
	}
	return status;
}

David Brownell's avatar
David Brownell committed
238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254
#ifdef CONFIG_GPIO_SYSFS

/* lock protects against unexport_gpio() being called while
 * sysfs files are active.
 */
static DEFINE_MUTEX(sysfs_lock);

/*
 * /sys/class/gpio/gpioN... only for GPIOs that are exported
 *   /direction
 *      * MAY BE OMITTED if kernel won't allow direction changes
 *      * is read/write as "in" or "out"
 *      * may also be written as "high" or "low", initializing
 *        output value as specified ("out" implies "low")
 *   /value
 *      * always readable, subject to hardware behavior
 *      * may be writable, as zero/nonzero
255 256 257 258
 *   /edge
 *      * configures behavior of poll(2) on /value
 *      * available only if pin can generate IRQs on input
 *      * is read/write as "none", "falling", "rising", or "both"
259 260 261 262 263
 *   /active_low
 *      * configures polarity of /value
 *      * is read/write as zero/nonzero
 *      * also affects existing and subsequent "falling" and "rising"
 *        /edge configuration
David Brownell's avatar
David Brownell committed
264 265 266 267 268
 */

static ssize_t gpio_direction_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
269
	const struct gpio_desc	*desc = dev_get_drvdata(dev);
David Brownell's avatar
David Brownell committed
270 271 272 273
	ssize_t			status;

	mutex_lock(&sysfs_lock);

274
	if (!test_bit(FLAG_EXPORT, &desc->flags)) {
David Brownell's avatar
David Brownell committed
275
		status = -EIO;
276
	} else {
277
		gpiod_get_direction(desc);
David Brownell's avatar
David Brownell committed
278 279 280
		status = sprintf(buf, "%s\n",
			test_bit(FLAG_IS_OUT, &desc->flags)
				? "out" : "in");
281
	}
David Brownell's avatar
David Brownell committed
282 283 284 285 286 287 288 289

	mutex_unlock(&sysfs_lock);
	return status;
}

static ssize_t gpio_direction_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t size)
{
290
	struct gpio_desc	*desc = dev_get_drvdata(dev);
David Brownell's avatar
David Brownell committed
291 292 293 294 295 296 297
	ssize_t			status;

	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags))
		status = -EIO;
	else if (sysfs_streq(buf, "high"))
298
		status = gpiod_direction_output(desc, 1);
David Brownell's avatar
David Brownell committed
299
	else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
300
		status = gpiod_direction_output(desc, 0);
David Brownell's avatar
David Brownell committed
301
	else if (sysfs_streq(buf, "in"))
302
		status = gpiod_direction_input(desc);
David Brownell's avatar
David Brownell committed
303 304 305 306 307 308 309
	else
		status = -EINVAL;

	mutex_unlock(&sysfs_lock);
	return status ? : size;
}

310
static /* const */ DEVICE_ATTR(direction, 0644,
David Brownell's avatar
David Brownell committed
311 312 313 314 315
		gpio_direction_show, gpio_direction_store);

static ssize_t gpio_value_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
316
	struct gpio_desc	*desc = dev_get_drvdata(dev);
David Brownell's avatar
David Brownell committed
317 318 319 320
	ssize_t			status;

	mutex_lock(&sysfs_lock);

321
	if (!test_bit(FLAG_EXPORT, &desc->flags)) {
David Brownell's avatar
David Brownell committed
322
		status = -EIO;
323 324 325
	} else {
		int value;

326
		value = !!gpiod_get_value_cansleep(desc);
327 328 329 330 331
		if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
			value = !value;

		status = sprintf(buf, "%d\n", value);
	}
David Brownell's avatar
David Brownell committed
332 333 334 335 336 337 338 339

	mutex_unlock(&sysfs_lock);
	return status;
}

static ssize_t gpio_value_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t size)
{
340
	struct gpio_desc	*desc = dev_get_drvdata(dev);
David Brownell's avatar
David Brownell committed
341 342 343 344 345 346 347 348 349 350 351 352 353
	ssize_t			status;

	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags))
		status = -EIO;
	else if (!test_bit(FLAG_IS_OUT, &desc->flags))
		status = -EPERM;
	else {
		long		value;

		status = strict_strtol(buf, 0, &value);
		if (status == 0) {
354 355
			if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
				value = !value;
356
			gpiod_set_value_cansleep(desc, value != 0);
David Brownell's avatar
David Brownell committed
357 358 359 360 361 362 363 364
			status = size;
		}
	}

	mutex_unlock(&sysfs_lock);
	return status;
}

365
static const DEVICE_ATTR(value, 0644,
David Brownell's avatar
David Brownell committed
366 367
		gpio_value_show, gpio_value_store);

368 369
static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
{
370
	struct sysfs_dirent	*value_sd = priv;
371

372
	sysfs_notify_dirent(value_sd);
373 374 375 376 377 378
	return IRQ_HANDLED;
}

static int gpio_setup_irq(struct gpio_desc *desc, struct device *dev,
		unsigned long gpio_flags)
{
379
	struct sysfs_dirent	*value_sd;
380 381 382 383 384 385
	unsigned long		irq_flags;
	int			ret, irq, id;

	if ((desc->flags & GPIO_TRIGGER_MASK) == gpio_flags)
		return 0;

386
	irq = gpiod_to_irq(desc);
387 388 389
	if (irq < 0)
		return -EIO;

390 391 392 393
	id = desc->flags >> ID_SHIFT;
	value_sd = idr_find(&dirent_idr, id);
	if (value_sd)
		free_irq(irq, value_sd);
394 395 396 397 398

	desc->flags &= ~GPIO_TRIGGER_MASK;

	if (!gpio_flags) {
		ret = 0;
399
		goto free_id;
400 401 402 403
	}

	irq_flags = IRQF_SHARED;
	if (test_bit(FLAG_TRIG_FALL, &gpio_flags))
404 405
		irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
			IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
406
	if (test_bit(FLAG_TRIG_RISE, &gpio_flags))
407 408
		irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
			IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
409

410 411 412 413
	if (!value_sd) {
		value_sd = sysfs_get_dirent(dev->kobj.sd, NULL, "value");
		if (!value_sd) {
			ret = -ENODEV;
414 415 416
			goto err_out;
		}

Tejun Heo's avatar
Tejun Heo committed
417 418
		ret = idr_alloc(&dirent_idr, value_sd, 1, 0, GFP_KERNEL);
		if (ret < 0)
419
			goto free_sd;
Tejun Heo's avatar
Tejun Heo committed
420
		id = ret;
421 422

		desc->flags &= GPIO_FLAGS_MASK;
423
		desc->flags |= (unsigned long)id << ID_SHIFT;
424

425
		if (desc->flags >> ID_SHIFT != id) {
426 427 428 429 430
			ret = -ERANGE;
			goto free_id;
		}
	}

431
	ret = request_any_context_irq(irq, gpio_sysfs_irq, irq_flags,
432
				"gpiolib", value_sd);
433
	if (ret < 0)
434
		goto free_id;
435 436 437 438 439

	desc->flags |= gpio_flags;
	return 0;

free_id:
440
	idr_remove(&dirent_idr, id);
441
	desc->flags &= GPIO_FLAGS_MASK;
442 443 444
free_sd:
	if (value_sd)
		sysfs_put(value_sd);
445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515
err_out:
	return ret;
}

static const struct {
	const char *name;
	unsigned long flags;
} trigger_types[] = {
	{ "none",    0 },
	{ "falling", BIT(FLAG_TRIG_FALL) },
	{ "rising",  BIT(FLAG_TRIG_RISE) },
	{ "both",    BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE) },
};

static ssize_t gpio_edge_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	const struct gpio_desc	*desc = dev_get_drvdata(dev);
	ssize_t			status;

	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags))
		status = -EIO;
	else {
		int i;

		status = 0;
		for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
			if ((desc->flags & GPIO_TRIGGER_MASK)
					== trigger_types[i].flags) {
				status = sprintf(buf, "%s\n",
						 trigger_types[i].name);
				break;
			}
	}

	mutex_unlock(&sysfs_lock);
	return status;
}

static ssize_t gpio_edge_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t size)
{
	struct gpio_desc	*desc = dev_get_drvdata(dev);
	ssize_t			status;
	int			i;

	for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
		if (sysfs_streq(trigger_types[i].name, buf))
			goto found;
	return -EINVAL;

found:
	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags))
		status = -EIO;
	else {
		status = gpio_setup_irq(desc, dev, trigger_types[i].flags);
		if (!status)
			status = size;
	}

	mutex_unlock(&sysfs_lock);

	return status;
}

static DEVICE_ATTR(edge, 0644, gpio_edge_show, gpio_edge_store);

516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585
static int sysfs_set_active_low(struct gpio_desc *desc, struct device *dev,
				int value)
{
	int			status = 0;

	if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
		return 0;

	if (value)
		set_bit(FLAG_ACTIVE_LOW, &desc->flags);
	else
		clear_bit(FLAG_ACTIVE_LOW, &desc->flags);

	/* reconfigure poll(2) support if enabled on one edge only */
	if (dev != NULL && (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^
				!!test_bit(FLAG_TRIG_FALL, &desc->flags))) {
		unsigned long trigger_flags = desc->flags & GPIO_TRIGGER_MASK;

		gpio_setup_irq(desc, dev, 0);
		status = gpio_setup_irq(desc, dev, trigger_flags);
	}

	return status;
}

static ssize_t gpio_active_low_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	const struct gpio_desc	*desc = dev_get_drvdata(dev);
	ssize_t			status;

	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags))
		status = -EIO;
	else
		status = sprintf(buf, "%d\n",
				!!test_bit(FLAG_ACTIVE_LOW, &desc->flags));

	mutex_unlock(&sysfs_lock);

	return status;
}

static ssize_t gpio_active_low_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t size)
{
	struct gpio_desc	*desc = dev_get_drvdata(dev);
	ssize_t			status;

	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags)) {
		status = -EIO;
	} else {
		long		value;

		status = strict_strtol(buf, 0, &value);
		if (status == 0)
			status = sysfs_set_active_low(desc, dev, value != 0);
	}

	mutex_unlock(&sysfs_lock);

	return status ? : size;
}

static const DEVICE_ATTR(active_low, 0644,
		gpio_active_low_show, gpio_active_low_store);

David Brownell's avatar
David Brownell committed
586 587
static const struct attribute *gpio_attrs[] = {
	&dev_attr_value.attr,
588
	&dev_attr_active_low.attr,
David Brownell's avatar
David Brownell committed
589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646
	NULL,
};

static const struct attribute_group gpio_attr_group = {
	.attrs = (struct attribute **) gpio_attrs,
};

/*
 * /sys/class/gpio/gpiochipN/
 *   /base ... matching gpio_chip.base (N)
 *   /label ... matching gpio_chip.label
 *   /ngpio ... matching gpio_chip.ngpio
 */

static ssize_t chip_base_show(struct device *dev,
			       struct device_attribute *attr, char *buf)
{
	const struct gpio_chip	*chip = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", chip->base);
}
static DEVICE_ATTR(base, 0444, chip_base_show, NULL);

static ssize_t chip_label_show(struct device *dev,
			       struct device_attribute *attr, char *buf)
{
	const struct gpio_chip	*chip = dev_get_drvdata(dev);

	return sprintf(buf, "%s\n", chip->label ? : "");
}
static DEVICE_ATTR(label, 0444, chip_label_show, NULL);

static ssize_t chip_ngpio_show(struct device *dev,
			       struct device_attribute *attr, char *buf)
{
	const struct gpio_chip	*chip = dev_get_drvdata(dev);

	return sprintf(buf, "%u\n", chip->ngpio);
}
static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL);

static const struct attribute *gpiochip_attrs[] = {
	&dev_attr_base.attr,
	&dev_attr_label.attr,
	&dev_attr_ngpio.attr,
	NULL,
};

static const struct attribute_group gpiochip_attr_group = {
	.attrs = (struct attribute **) gpiochip_attrs,
};

/*
 * /sys/class/gpio/export ... write-only
 *	integer N ... number of GPIO to export (full access)
 * /sys/class/gpio/unexport ... write-only
 *	integer N ... number of GPIO to unexport
 */
647 648 649
static ssize_t export_store(struct class *class,
				struct class_attribute *attr,
				const char *buf, size_t len)
David Brownell's avatar
David Brownell committed
650
{
651 652 653
	long			gpio;
	struct gpio_desc	*desc;
	int			status;
David Brownell's avatar
David Brownell committed
654 655 656 657 658

	status = strict_strtol(buf, 0, &gpio);
	if (status < 0)
		goto done;

659
	desc = gpio_to_desc(gpio);
660 661 662 663 664
	/* reject invalid GPIOs */
	if (!desc) {
		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
		return -EINVAL;
	}
665

David Brownell's avatar
David Brownell committed
666 667 668 669 670
	/* No extra locking here; FLAG_SYSFS just signifies that the
	 * request and export were done by on behalf of userspace, so
	 * they may be undone on its behalf too.
	 */

671
	status = gpiod_request(desc, "sysfs");
672 673 674
	if (status < 0) {
		if (status == -EPROBE_DEFER)
			status = -ENODEV;
David Brownell's avatar
David Brownell committed
675
		goto done;
676
	}
677
	status = gpiod_export(desc, true);
David Brownell's avatar
David Brownell committed
678
	if (status < 0)
679
		gpiod_free(desc);
David Brownell's avatar
David Brownell committed
680
	else
681
		set_bit(FLAG_SYSFS, &desc->flags);
David Brownell's avatar
David Brownell committed
682 683 684 685 686 687 688

done:
	if (status)
		pr_debug("%s: status %d\n", __func__, status);
	return status ? : len;
}

689 690 691
static ssize_t unexport_store(struct class *class,
				struct class_attribute *attr,
				const char *buf, size_t len)
David Brownell's avatar
David Brownell committed
692
{
693 694 695
	long			gpio;
	struct gpio_desc	*desc;
	int			status;
David Brownell's avatar
David Brownell committed
696 697 698 699 700

	status = strict_strtol(buf, 0, &gpio);
	if (status < 0)
		goto done;

701
	desc = gpio_to_desc(gpio);
David Brownell's avatar
David Brownell committed
702
	/* reject bogus commands (gpio_unexport ignores them) */
703 704 705 706 707 708
	if (!desc) {
		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
		return -EINVAL;
	}

	status = -EINVAL;
David Brownell's avatar
David Brownell committed
709 710 711 712 713

	/* No extra locking here; FLAG_SYSFS just signifies that the
	 * request and export were done by on behalf of userspace, so
	 * they may be undone on its behalf too.
	 */
714
	if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
David Brownell's avatar
David Brownell committed
715
		status = 0;
716
		gpiod_free(desc);
David Brownell's avatar
David Brownell committed
717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752
	}
done:
	if (status)
		pr_debug("%s: status %d\n", __func__, status);
	return status ? : len;
}

static struct class_attribute gpio_class_attrs[] = {
	__ATTR(export, 0200, NULL, export_store),
	__ATTR(unexport, 0200, NULL, unexport_store),
	__ATTR_NULL,
};

static struct class gpio_class = {
	.name =		"gpio",
	.owner =	THIS_MODULE,

	.class_attrs =	gpio_class_attrs,
};


/**
 * gpio_export - export a GPIO through sysfs
 * @gpio: gpio to make available, already requested
 * @direction_may_change: true if userspace may change gpio direction
 * Context: arch_initcall or later
 *
 * When drivers want to make a GPIO accessible to userspace after they
 * have requested it -- perhaps while debugging, or as part of their
 * public interface -- they may use this routine.  If the GPIO can
 * change direction (some can't) and the caller allows it, userspace
 * will see "direction" sysfs attribute which may be used to change
 * the gpio's direction.  A "value" attribute will always be provided.
 *
 * Returns zero on success, else an error.
 */
753
static int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
David Brownell's avatar
David Brownell committed
754 755
{
	unsigned long		flags;
Ryan Mallon's avatar
Ryan Mallon committed
756
	int			status;
757
	const char		*ioname = NULL;
Ryan Mallon's avatar
Ryan Mallon committed
758
	struct device		*dev;
759
	int			offset;
David Brownell's avatar
David Brownell committed
760 761 762 763 764 765 766

	/* can't export until sysfs is available ... */
	if (!gpio_class.p) {
		pr_debug("%s: called too early!\n", __func__);
		return -ENOENT;
	}

767 768
	if (!desc) {
		pr_debug("%s: invalid gpio descriptor\n", __func__);
Ryan Mallon's avatar
Ryan Mallon committed
769 770
		return -EINVAL;
	}
David Brownell's avatar
David Brownell committed
771 772 773 774

	mutex_lock(&sysfs_lock);

	spin_lock_irqsave(&gpio_lock, flags);
Ryan Mallon's avatar
Ryan Mallon committed
775 776 777 778
	if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
	     test_bit(FLAG_EXPORT, &desc->flags)) {
		spin_unlock_irqrestore(&gpio_lock, flags);
		pr_debug("%s: gpio %d unavailable (requested=%d, exported=%d)\n",
779
				__func__, desc_to_gpio(desc),
Ryan Mallon's avatar
Ryan Mallon committed
780 781
				test_bit(FLAG_REQUESTED, &desc->flags),
				test_bit(FLAG_EXPORT, &desc->flags));
782 783
		status = -EPERM;
		goto fail_unlock;
David Brownell's avatar
David Brownell committed
784
	}
Ryan Mallon's avatar
Ryan Mallon committed
785 786 787

	if (!desc->chip->direction_input || !desc->chip->direction_output)
		direction_may_change = false;
David Brownell's avatar
David Brownell committed
788 789
	spin_unlock_irqrestore(&gpio_lock, flags);

790 791 792
	offset = gpio_chip_hwgpio(desc);
	if (desc->chip->names && desc->chip->names[offset])
		ioname = desc->chip->names[offset];
793

Ryan Mallon's avatar
Ryan Mallon committed
794
	dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
795 796
			    desc, ioname ? ioname : "gpio%u",
			    desc_to_gpio(desc));
Ryan Mallon's avatar
Ryan Mallon committed
797 798 799
	if (IS_ERR(dev)) {
		status = PTR_ERR(dev);
		goto fail_unlock;
David Brownell's avatar
David Brownell committed
800 801
	}

Ryan Mallon's avatar
Ryan Mallon committed
802
	status = sysfs_create_group(&dev->kobj, &gpio_attr_group);
David Brownell's avatar
David Brownell committed
803
	if (status)
Ryan Mallon's avatar
Ryan Mallon committed
804
		goto fail_unregister_device;
David Brownell's avatar
David Brownell committed
805

Ryan Mallon's avatar
Ryan Mallon committed
806 807 808 809 810 811
	if (direction_may_change) {
		status = device_create_file(dev, &dev_attr_direction);
		if (status)
			goto fail_unregister_device;
	}

812
	if (gpiod_to_irq(desc) >= 0 && (direction_may_change ||
Ryan Mallon's avatar
Ryan Mallon committed
813 814 815 816 817
				       !test_bit(FLAG_IS_OUT, &desc->flags))) {
		status = device_create_file(dev, &dev_attr_edge);
		if (status)
			goto fail_unregister_device;
	}
David Brownell's avatar
David Brownell committed
818

Ryan Mallon's avatar
Ryan Mallon committed
819 820 821 822 823 824 825 826
	set_bit(FLAG_EXPORT, &desc->flags);
	mutex_unlock(&sysfs_lock);
	return 0;

fail_unregister_device:
	device_unregister(dev);
fail_unlock:
	mutex_unlock(&sysfs_lock);
827 828
	pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
		 status);
David Brownell's avatar
David Brownell committed
829 830
	return status;
}
831 832 833 834 835

int gpio_export(unsigned gpio, bool direction_may_change)
{
	return gpiod_export(gpio_to_desc(gpio), direction_may_change);
}
David Brownell's avatar
David Brownell committed
836 837
EXPORT_SYMBOL_GPL(gpio_export);

838
static int match_export(struct device *dev, const void *data)
David Brownell's avatar
David Brownell committed
839 840 841 842
{
	return dev_get_drvdata(dev) == data;
}

843 844 845 846 847 848 849 850 851 852 853
/**
 * gpio_export_link - create a sysfs link to an exported GPIO node
 * @dev: device under which to create symlink
 * @name: name of the symlink
 * @gpio: gpio to create symlink to, already exported
 *
 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
 * node. Caller is responsible for unlinking.
 *
 * Returns zero on success, else an error.
 */
854 855
static int gpiod_export_link(struct device *dev, const char *name,
			     struct gpio_desc *desc)
856 857 858
{
	int			status = -EINVAL;

859 860 861 862
	if (!desc) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}
863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880

	mutex_lock(&sysfs_lock);

	if (test_bit(FLAG_EXPORT, &desc->flags)) {
		struct device *tdev;

		tdev = class_find_device(&gpio_class, NULL, desc, match_export);
		if (tdev != NULL) {
			status = sysfs_create_link(&dev->kobj, &tdev->kobj,
						name);
		} else {
			status = -ENODEV;
		}
	}

	mutex_unlock(&sysfs_lock);

	if (status)
881 882
		pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
			 status);
883 884 885 886

	return status;
}

887 888 889 890 891
int gpio_export_link(struct device *dev, const char *name, unsigned gpio)
{
	return gpiod_export_link(dev, name, gpio_to_desc(gpio));
}
EXPORT_SYMBOL_GPL(gpio_export_link);
892 893 894 895 896 897 898 899 900 901 902 903 904

/**
 * gpio_sysfs_set_active_low - set the polarity of gpio sysfs value
 * @gpio: gpio to change
 * @value: non-zero to use active low, i.e. inverted values
 *
 * Set the polarity of /sys/class/gpio/gpioN/value sysfs attribute.
 * The GPIO does not have to be exported yet.  If poll(2) support has
 * been enabled for either rising or falling edge, it will be
 * reconfigured to follow the new polarity.
 *
 * Returns zero on success, else an error.
 */
905
static int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
906 907 908 909
{
	struct device		*dev = NULL;
	int			status = -EINVAL;

910 911 912 913
	if (!desc) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}
914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930

	mutex_lock(&sysfs_lock);

	if (test_bit(FLAG_EXPORT, &desc->flags)) {
		dev = class_find_device(&gpio_class, NULL, desc, match_export);
		if (dev == NULL) {
			status = -ENODEV;
			goto unlock;
		}
	}

	status = sysfs_set_active_low(desc, dev, value);

unlock:
	mutex_unlock(&sysfs_lock);

	if (status)
931 932
		pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
			 status);
933 934 935

	return status;
}
936 937 938 939 940

int gpio_sysfs_set_active_low(unsigned gpio, int value)
{
	return gpiod_sysfs_set_active_low(gpio_to_desc(gpio), value);
}
941 942
EXPORT_SYMBOL_GPL(gpio_sysfs_set_active_low);

David Brownell's avatar
David Brownell committed
943 944 945 946 947 948
/**
 * gpio_unexport - reverse effect of gpio_export()
 * @gpio: gpio to make unavailable
 *
 * This is implicit on gpio_free().
 */
949
static void gpiod_unexport(struct gpio_desc *desc)
David Brownell's avatar
David Brownell committed
950
{
951
	int			status = 0;
952
	struct device		*dev = NULL;
David Brownell's avatar
David Brownell committed
953

954
	if (!desc) {
955 956
		pr_warn("%s: invalid GPIO\n", __func__);
		return;
957
	}
David Brownell's avatar
David Brownell committed
958 959 960 961 962 963 964

	mutex_lock(&sysfs_lock);

	if (test_bit(FLAG_EXPORT, &desc->flags)) {

		dev = class_find_device(&gpio_class, NULL, desc, match_export);
		if (dev) {
965
			gpio_setup_irq(desc, dev, 0);
David Brownell's avatar
David Brownell committed
966 967 968 969 970 971
			clear_bit(FLAG_EXPORT, &desc->flags);
		} else
			status = -ENODEV;
	}

	mutex_unlock(&sysfs_lock);
972

973 974 975 976
	if (dev) {
		device_unregister(dev);
		put_device(dev);
	}
977

David Brownell's avatar
David Brownell committed
978
	if (status)
979 980 981 982 983 984 985
		pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
			 status);
}

void gpio_unexport(unsigned gpio)
{
	gpiod_unexport(gpio_to_desc(gpio));
David Brownell's avatar
David Brownell committed
986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005
}
EXPORT_SYMBOL_GPL(gpio_unexport);

static int gpiochip_export(struct gpio_chip *chip)
{
	int		status;
	struct device	*dev;

	/* Many systems register gpio chips for SOC support very early,
	 * before driver model support is available.  In those cases we
	 * export this later, in gpiolib_sysfs_init() ... here we just
	 * verify that _some_ field of gpio_class got initialized.
	 */
	if (!gpio_class.p)
		return 0;

	/* use chip->base for the ID; it's already known to be unique */
	mutex_lock(&sysfs_lock);
	dev = device_create(&gpio_class, chip->dev, MKDEV(0, 0), chip,
				"gpiochip%d", chip->base);
1006
	if (!IS_ERR(dev)) {
David Brownell's avatar
David Brownell committed
1007 1008 1009
		status = sysfs_create_group(&dev->kobj,
				&gpiochip_attr_group);
	} else
1010
		status = PTR_ERR(dev);
David Brownell's avatar
David Brownell committed
1011 1012 1013 1014 1015 1016 1017 1018
	chip->exported = (status == 0);
	mutex_unlock(&sysfs_lock);

	if (status) {
		unsigned long	flags;
		unsigned	gpio;

		spin_lock_irqsave(&gpio_lock, flags);
1019 1020 1021
		gpio = 0;
		while (gpio < chip->ngpio)
			chip->desc[gpio++].chip = NULL;
David Brownell's avatar
David Brownell committed
1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055
		spin_unlock_irqrestore(&gpio_lock, flags);

		pr_debug("%s: chip %s status %d\n", __func__,
				chip->label, status);
	}

	return status;
}

static void gpiochip_unexport(struct gpio_chip *chip)
{
	int			status;
	struct device		*dev;

	mutex_lock(&sysfs_lock);
	dev = class_find_device(&gpio_class, NULL, chip, match_export);
	if (dev) {
		put_device(dev);
		device_unregister(dev);
		chip->exported = 0;
		status = 0;
	} else
		status = -ENODEV;
	mutex_unlock(&sysfs_lock);

	if (status)
		pr_debug("%s: chip %s status %d\n", __func__,
				chip->label, status);
}

static int __init gpiolib_sysfs_init(void)
{
	int		status;
	unsigned long	flags;
1056
	struct gpio_chip *chip;
David Brownell's avatar
David Brownell committed
1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068

	status = class_register(&gpio_class);
	if (status < 0)
		return status;

	/* Scan and register the gpio_chips which registered very
	 * early (e.g. before the class_register above was called).
	 *
	 * We run before arch_initcall() so chip->dev nodes can have
	 * registered, and so arch_initcall() can always gpio_export().
	 */
	spin_lock_irqsave(&gpio_lock, flags);
1069
	list_for_each_entry(chip, &gpio_chips, list) {
David Brownell's avatar
David Brownell committed
1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093
		if (!chip || chip->exported)
			continue;

		spin_unlock_irqrestore(&gpio_lock, flags);
		status = gpiochip_export(chip);
		spin_lock_irqsave(&gpio_lock, flags);
	}
	spin_unlock_irqrestore(&gpio_lock, flags);


	return status;
}
postcore_initcall(gpiolib_sysfs_init);

#else
static inline int gpiochip_export(struct gpio_chip *chip)
{
	return 0;
}

static inline void gpiochip_unexport(struct gpio_chip *chip)
{
}

1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114
static inline int gpiod_export(struct gpio_desc *desc,
			       bool direction_may_change)
{
	return -ENOSYS;
}

static inline int gpiod_export_link(struct device *dev, const char *name,
				    struct gpio_desc *desc)
{
	return -ENOSYS;
}

static inline int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
{
	return -ENOSYS;
}

static inline void gpiod_unexport(struct gpio_desc *desc)
{
}

David Brownell's avatar
David Brownell committed
1115 1116
#endif /* CONFIG_GPIO_SYSFS */

1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153
/*
 * Add a new chip to the global chips list, keeping the list of chips sorted
 * by base order.
 *
 * Return -EBUSY if the new chip overlaps with some other chip's integer
 * space.
 */
static int gpiochip_add_to_list(struct gpio_chip *chip)
{
	struct list_head *pos = &gpio_chips;
	struct gpio_chip *_chip;
	int err = 0;

	/* find where to insert our chip */
	list_for_each(pos, &gpio_chips) {
		_chip = list_entry(pos, struct gpio_chip, list);
		/* shall we insert before _chip? */
		if (_chip->base >= chip->base + chip->ngpio)
			break;
	}

	/* are we stepping on the chip right before? */
	if (pos != &gpio_chips && pos->prev != &gpio_chips) {
		_chip = list_entry(pos->prev, struct gpio_chip, list);
		if (_chip->base + _chip->ngpio > chip->base) {
			dev_err(chip->dev,
			       "GPIO integer space overlap, cannot add chip\n");
			err = -EBUSY;
		}
	}

	if (!err)
		list_add_tail(&chip->list, pos);

	return err;
}

1154 1155 1156 1157 1158 1159 1160 1161
/**
 * gpiochip_add() - register a gpio_chip
 * @chip: the chip to register, with chip->base initialized
 * Context: potentially before irqs or kmalloc will work
 *
 * Returns a negative errno if the chip can't be registered, such as
 * because the chip->base is invalid or already associated with a
 * different chip.  Otherwise it returns zero as a success code.
1162
 *
David Brownell's avatar
David Brownell committed
1163 1164 1165 1166 1167
 * When gpiochip_add() is called very early during boot, so that GPIOs
 * can be freely used, the chip->dev device must be registered before
 * the gpio framework's arch_initcall().  Otherwise sysfs initialization
 * for GPIOs will fail rudely.
 *
1168 1169
 * If chip->base is negative, this requests dynamic assignment of
 * a range of valid GPIOs.
1170 1171 1172 1173 1174 1175
 */
int gpiochip_add(struct gpio_chip *chip)
{
	unsigned long	flags;
	int		status = 0;
	unsigned	id;
1176
	int		base = chip->base;
1177

Trent Piepho's avatar
Trent Piepho committed
1178
	if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
1179
			&& base >= 0) {
1180 1181 1182 1183 1184 1185
		status = -EINVAL;
		goto fail;
	}

	spin_lock_irqsave(&gpio_lock, flags);

1186 1187 1188 1189
	if (base < 0) {
		base = gpiochip_find_base(chip->ngpio);
		if (base < 0) {
			status = base;
David Brownell's avatar
David Brownell committed
1190
			goto unlock;
1191 1192 1193 1194
		}
		chip->base = base;
	}

1195 1196
	status = gpiochip_add_to_list(chip);

1197
	if (status == 0) {
1198 1199 1200 1201 1202
		chip->desc = &gpio_desc[chip->base];

		for (id = 0; id < chip->ngpio; id++) {
			struct gpio_desc *desc = &chip->desc[id];
			desc->chip = chip;
David Brownell's avatar
David Brownell committed
1203 1204 1205 1206 1207

			/* REVISIT:  most hardware initializes GPIOs as
			 * inputs (often with pullups enabled) so power
			 * usage is minimized.  Linux code should set the
			 * gpio direction first thing; but until it does,
1208
			 * and in case chip->get_direction is not set,
David Brownell's avatar
David Brownell committed
1209 1210
			 * we may expose the wrong direction in sysfs.
			 */
1211
			desc->flags = !chip->direction_input
David Brownell's avatar
David Brownell committed
1212 1213
				? (1 << FLAG_IS_OUT)
				: 0;
1214 1215 1216
		}
	}

1217 1218 1219 1220
#ifdef CONFIG_PINCTRL
	INIT_LIST_HEAD(&chip->pin_ranges);
#endif

1221 1222
	of_gpiochip_add(chip);

David Brownell's avatar
David Brownell committed
1223
unlock:
1224
	spin_unlock_irqrestore(&gpio_lock, flags);
1225 1226 1227 1228 1229 1230 1231 1232

	if (status)
		goto fail;

	status = gpiochip_export(chip);
	if (status)
		goto fail;

1233
	pr_debug("gpiochip_add: registered GPIOs %d to %d on device: %s\n",
1234 1235 1236
		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");

1237
	return 0;
1238 1239
fail:
	/* failures here can mean systems won't boot... */
1240 1241 1242
	pr_err("gpiochip_add: gpios %d..%d (%s) failed to register\n",
		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");
1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260
	return status;
}
EXPORT_SYMBOL_GPL(gpiochip_add);

/**
 * gpiochip_remove() - unregister a gpio_chip
 * @chip: the chip to unregister
 *
 * A gpio_chip with any GPIOs still requested may not be removed.
 */
int gpiochip_remove(struct gpio_chip *chip)
{
	unsigned long	flags;
	int		status = 0;
	unsigned	id;

	spin_lock_irqsave(&gpio_lock, flags);

1261
	gpiochip_remove_pin_ranges(chip);
1262 1263
	of_gpiochip_remove(chip);

1264 1265
	for (id = 0; id < chip->ngpio; id++) {
		if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) {
1266 1267 1268 1269 1270
			status = -EBUSY;
			break;
		}
	}
	if (status == 0) {
1271 1272
		for (id = 0; id < chip->ngpio; id++)
			chip->desc[id].chip = NULL;
1273 1274

		list_del(&chip->list);
1275 1276 1277
	}

	spin_unlock_irqrestore(&gpio_lock, flags);
David Brownell's avatar
David Brownell committed
1278 1279 1280 1281

	if (status == 0)
		gpiochip_unexport(chip);

1282 1283 1284 1285
	return status;
}
EXPORT_SYMBOL_GPL(gpiochip_remove);

1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296
/**
 * gpiochip_find() - iterator for locating a specific gpio_chip
 * @data: data to pass to match function
 * @callback: Callback function to check gpio_chip
 *
 * Similar to bus_find_device.  It returns a reference to a gpio_chip as
 * determined by a user supplied @match callback.  The callback should return
 * 0 if the device doesn't match and non-zero if it does.  If the callback is
 * non-zero, this function will return to the caller and not iterate over any
 * more gpio_chips.
 */
1297
struct gpio_chip *gpiochip_find(void *data,
1298
				int (*match)(struct gpio_chip *chip,
1299
					     void *data))
1300
{
1301
	struct gpio_chip *chip;
1302