gpiolib.c 52.7 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 91 92 93 94 95 96 97 98 99 100 101 102 103 104
/*
 * 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);
static int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce);
static int gpiod_get_value_cansleep(struct gpio_desc *desc);
static void gpiod_set_value_cansleep(struct gpio_desc *desc, int value);
static int gpiod_get_value(struct gpio_desc *desc);
static void gpiod_set_value(struct gpio_desc *desc, int value);
static int gpiod_cansleep(struct gpio_desc *desc);
static int gpiod_to_irq(struct gpio_desc *desc);
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);


105 106 107 108 109 110 111
static inline void desc_set_label(struct gpio_desc *d, const char *label)
{
#ifdef CONFIG_DEBUG_FS
	d->label = label;
#endif
}

112 113 114 115 116
/*
 * Return the GPIO number of the passed descriptor relative to its chip
 */
static int gpio_chip_hwgpio(const struct gpio_desc *desc)
{
117
	return desc - &desc->chip->desc[0];
118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137
}

/**
 * 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)
{
138
	return desc->chip->base + gpio_chip_hwgpio(desc);
139 140 141
}


142 143 144 145
/* 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
146 147
 * message should motivate switching to explicit requests... so should
 * the weaker cleanup after faults, compared to gpio_request().
148 149 150 151
 *
 * 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.
152
 */
153
static int gpio_ensure_requested(struct gpio_desc *desc)
154
{
155
	const struct gpio_chip *chip = desc->chip;
156
	const int gpio = desc_to_gpio(desc);
David Brownell's avatar
David Brownell committed
157

158 159
	if (WARN(test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0,
			"autorequest GPIO-%d\n", gpio)) {
David Brownell's avatar
David Brownell committed
160 161 162 163 164 165
		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;
		}
166
		desc_set_label(desc, "[auto]");
David Brownell's avatar
David Brownell committed
167 168 169
		/* caller must chip->request() w/o spinlock */
		if (chip->request)
			return 1;
170
	}
David Brownell's avatar
David Brownell committed
171
	return 0;
172 173 174
}

/* caller holds gpio_lock *OR* gpio is marked as requested */
175 176 177 178 179
static struct gpio_chip *gpiod_to_chip(struct gpio_desc *desc)
{
	return desc->chip;
}

180
struct gpio_chip *gpio_to_chip(unsigned gpio)
181
{
182
	return gpiod_to_chip(gpio_to_desc(gpio));
183 184
}

185 186 187
/* dynamic allocation of GPIOs, e.g. on a hotplugged device */
static int gpiochip_find_base(int ngpio)
{
188 189
	struct gpio_chip *chip;
	int base = ARCH_NR_GPIOS - ngpio;
190

191 192 193 194 195 196 197
	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;
198 199
	}

200
	if (gpio_is_valid(base)) {
201
		pr_debug("%s: found new base at %d\n", __func__, base);
202 203 204 205
		return base;
	} else {
		pr_err("%s: cannot find free range\n", __func__);
		return -ENOSPC;
Anton Vorontsov's avatar
Anton Vorontsov committed
206 207 208
	}
}

209
/* caller ensures gpio is valid and requested, chip->get_direction may sleep  */
210
static int gpiod_get_direction(struct gpio_desc *desc)
211 212
{
	struct gpio_chip	*chip;
213
	unsigned		offset;
214 215
	int			status = -EINVAL;

216 217
	chip = gpiod_to_chip(desc);
	offset = gpio_chip_hwgpio(desc);
218 219 220 221

	if (!chip->get_direction)
		return status;

222
	status = chip->get_direction(chip, offset);
223 224 225 226 227 228 229 230 231 232 233 234
	if (status > 0) {
		/* GPIOF_DIR_IN, or other positive */
		status = 1;
		clear_bit(FLAG_IS_OUT, &desc->flags);
	}
	if (status == 0) {
		/* GPIOF_DIR_OUT */
		set_bit(FLAG_IS_OUT, &desc->flags);
	}
	return status;
}

David Brownell's avatar
David Brownell committed
235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251
#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
252 253 254 255
 *   /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"
256 257 258 259 260
 *   /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
261 262 263 264 265
 */

static ssize_t gpio_direction_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
266
	struct gpio_desc	*desc = dev_get_drvdata(dev);
David Brownell's avatar
David Brownell committed
267 268 269 270
	ssize_t			status;

	mutex_lock(&sysfs_lock);

271
	if (!test_bit(FLAG_EXPORT, &desc->flags)) {
David Brownell's avatar
David Brownell committed
272
		status = -EIO;
273
	} else {
274
		gpiod_get_direction(desc);
David Brownell's avatar
David Brownell committed
275 276 277
		status = sprintf(buf, "%s\n",
			test_bit(FLAG_IS_OUT, &desc->flags)
				? "out" : "in");
278
	}
David Brownell's avatar
David Brownell committed
279 280 281 282 283 284 285 286

	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)
{
287
	struct gpio_desc	*desc = dev_get_drvdata(dev);
David Brownell's avatar
David Brownell committed
288 289 290 291 292 293 294
	ssize_t			status;

	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags))
		status = -EIO;
	else if (sysfs_streq(buf, "high"))
295
		status = gpiod_direction_output(desc, 1);
David Brownell's avatar
David Brownell committed
296
	else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
297
		status = gpiod_direction_output(desc, 0);
David Brownell's avatar
David Brownell committed
298
	else if (sysfs_streq(buf, "in"))
299
		status = gpiod_direction_input(desc);
David Brownell's avatar
David Brownell committed
300 301 302 303 304 305 306
	else
		status = -EINVAL;

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

307
static /* const */ DEVICE_ATTR(direction, 0644,
David Brownell's avatar
David Brownell committed
308 309 310 311 312
		gpio_direction_show, gpio_direction_store);

static ssize_t gpio_value_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
313
	struct gpio_desc	*desc = dev_get_drvdata(dev);
David Brownell's avatar
David Brownell committed
314 315 316 317
	ssize_t			status;

	mutex_lock(&sysfs_lock);

318
	if (!test_bit(FLAG_EXPORT, &desc->flags)) {
David Brownell's avatar
David Brownell committed
319
		status = -EIO;
320 321 322
	} else {
		int value;

323
		value = !!gpiod_get_value_cansleep(desc);
324 325 326 327 328
		if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
			value = !value;

		status = sprintf(buf, "%d\n", value);
	}
David Brownell's avatar
David Brownell committed
329 330 331 332 333 334 335 336

	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)
{
337
	struct gpio_desc	*desc = dev_get_drvdata(dev);
David Brownell's avatar
David Brownell committed
338 339 340 341 342 343 344 345 346 347 348 349 350
	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) {
351 352
			if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
				value = !value;
353
			gpiod_set_value_cansleep(desc, value != 0);
David Brownell's avatar
David Brownell committed
354 355 356 357 358 359 360 361
			status = size;
		}
	}

	mutex_unlock(&sysfs_lock);
	return status;
}

362
static const DEVICE_ATTR(value, 0644,
David Brownell's avatar
David Brownell committed
363 364
		gpio_value_show, gpio_value_store);

365 366
static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
{
367
	struct sysfs_dirent	*value_sd = priv;
368

369
	sysfs_notify_dirent(value_sd);
370 371 372 373 374 375
	return IRQ_HANDLED;
}

static int gpio_setup_irq(struct gpio_desc *desc, struct device *dev,
		unsigned long gpio_flags)
{
376
	struct sysfs_dirent	*value_sd;
377 378 379 380 381 382
	unsigned long		irq_flags;
	int			ret, irq, id;

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

383
	irq = gpiod_to_irq(desc);
384 385 386
	if (irq < 0)
		return -EIO;

387 388 389 390
	id = desc->flags >> ID_SHIFT;
	value_sd = idr_find(&dirent_idr, id);
	if (value_sd)
		free_irq(irq, value_sd);
391 392 393 394 395

	desc->flags &= ~GPIO_TRIGGER_MASK;

	if (!gpio_flags) {
		ret = 0;
396
		goto free_id;
397 398 399 400
	}

	irq_flags = IRQF_SHARED;
	if (test_bit(FLAG_TRIG_FALL, &gpio_flags))
401 402
		irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
			IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
403
	if (test_bit(FLAG_TRIG_RISE, &gpio_flags))
404 405
		irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
			IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
406

407 408 409 410
	if (!value_sd) {
		value_sd = sysfs_get_dirent(dev->kobj.sd, NULL, "value");
		if (!value_sd) {
			ret = -ENODEV;
411 412 413
			goto err_out;
		}

Tejun Heo's avatar
Tejun Heo committed
414 415
		ret = idr_alloc(&dirent_idr, value_sd, 1, 0, GFP_KERNEL);
		if (ret < 0)
416
			goto free_sd;
Tejun Heo's avatar
Tejun Heo committed
417
		id = ret;
418 419

		desc->flags &= GPIO_FLAGS_MASK;
420
		desc->flags |= (unsigned long)id << ID_SHIFT;
421

422
		if (desc->flags >> ID_SHIFT != id) {
423 424 425 426 427
			ret = -ERANGE;
			goto free_id;
		}
	}

428
	ret = request_any_context_irq(irq, gpio_sysfs_irq, irq_flags,
429
				"gpiolib", value_sd);
430
	if (ret < 0)
431
		goto free_id;
432 433 434 435 436

	desc->flags |= gpio_flags;
	return 0;

free_id:
437
	idr_remove(&dirent_idr, id);
438
	desc->flags &= GPIO_FLAGS_MASK;
439 440 441
free_sd:
	if (value_sd)
		sysfs_put(value_sd);
442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512
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);

513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582
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
583 584
static const struct attribute *gpio_attrs[] = {
	&dev_attr_value.attr,
585
	&dev_attr_active_low.attr,
David Brownell's avatar
David Brownell committed
586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643
	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
 */
644 645 646
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
647
{
648 649 650
	long			gpio;
	struct gpio_desc	*desc;
	int			status;
David Brownell's avatar
David Brownell committed
651 652 653 654 655

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

656 657
	desc = gpio_to_desc(gpio);

David Brownell's avatar
David Brownell committed
658 659 660 661 662
	/* 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.
	 */

663
	status = gpiod_request(desc, "sysfs");
664 665 666
	if (status < 0) {
		if (status == -EPROBE_DEFER)
			status = -ENODEV;
David Brownell's avatar
David Brownell committed
667
		goto done;
668
	}
669
	status = gpiod_export(desc, true);
David Brownell's avatar
David Brownell committed
670
	if (status < 0)
671
		gpiod_free(desc);
David Brownell's avatar
David Brownell committed
672
	else
673
		set_bit(FLAG_SYSFS, &desc->flags);
David Brownell's avatar
David Brownell committed
674 675 676 677 678 679 680

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

681 682 683
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
684
{
685 686 687
	long			gpio;
	struct gpio_desc	*desc;
	int			status;
David Brownell's avatar
David Brownell committed
688 689 690 691 692 693 694

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

	status = -EINVAL;

695
	desc = gpio_to_desc(gpio);
David Brownell's avatar
David Brownell committed
696
	/* reject bogus commands (gpio_unexport ignores them) */
697
	if (!desc)
David Brownell's avatar
David Brownell committed
698 699 700 701 702 703
		goto done;

	/* 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.
	 */
704
	if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
David Brownell's avatar
David Brownell committed
705
		status = 0;
706
		gpiod_free(desc);
David Brownell's avatar
David Brownell committed
707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742
	}
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.
 */
743
static int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
David Brownell's avatar
David Brownell committed
744 745
{
	unsigned long		flags;
Ryan Mallon's avatar
Ryan Mallon committed
746
	int			status;
747
	const char		*ioname = NULL;
Ryan Mallon's avatar
Ryan Mallon committed
748
	struct device		*dev;
749
	int			offset;
David Brownell's avatar
David Brownell committed
750 751 752 753 754 755 756

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

757 758
	if (!desc) {
		pr_debug("%s: invalid gpio descriptor\n", __func__);
Ryan Mallon's avatar
Ryan Mallon committed
759 760
		return -EINVAL;
	}
David Brownell's avatar
David Brownell committed
761 762 763 764

	mutex_lock(&sysfs_lock);

	spin_lock_irqsave(&gpio_lock, flags);
Ryan Mallon's avatar
Ryan Mallon committed
765 766 767 768
	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",
769
				__func__, desc_to_gpio(desc),
Ryan Mallon's avatar
Ryan Mallon committed
770 771
				test_bit(FLAG_REQUESTED, &desc->flags),
				test_bit(FLAG_EXPORT, &desc->flags));
772 773
		status = -EPERM;
		goto fail_unlock;
David Brownell's avatar
David Brownell committed
774
	}
Ryan Mallon's avatar
Ryan Mallon committed
775 776 777

	if (!desc->chip->direction_input || !desc->chip->direction_output)
		direction_may_change = false;
David Brownell's avatar
David Brownell committed
778 779
	spin_unlock_irqrestore(&gpio_lock, flags);

780 781 782
	offset = gpio_chip_hwgpio(desc);
	if (desc->chip->names && desc->chip->names[offset])
		ioname = desc->chip->names[offset];
783

Ryan Mallon's avatar
Ryan Mallon committed
784
	dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
785 786
			    desc, ioname ? ioname : "gpio%u",
			    desc_to_gpio(desc));
Ryan Mallon's avatar
Ryan Mallon committed
787 788 789
	if (IS_ERR(dev)) {
		status = PTR_ERR(dev);
		goto fail_unlock;
David Brownell's avatar
David Brownell committed
790 791
	}

Ryan Mallon's avatar
Ryan Mallon committed
792
	status = sysfs_create_group(&dev->kobj, &gpio_attr_group);
David Brownell's avatar
David Brownell committed
793
	if (status)
Ryan Mallon's avatar
Ryan Mallon committed
794
		goto fail_unregister_device;
David Brownell's avatar
David Brownell committed
795

Ryan Mallon's avatar
Ryan Mallon committed
796 797 798 799 800 801
	if (direction_may_change) {
		status = device_create_file(dev, &dev_attr_direction);
		if (status)
			goto fail_unregister_device;
	}

802
	if (gpiod_to_irq(desc) >= 0 && (direction_may_change ||
Ryan Mallon's avatar
Ryan Mallon committed
803 804 805 806 807
				       !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
808

Ryan Mallon's avatar
Ryan Mallon committed
809 810 811 812 813 814 815 816
	set_bit(FLAG_EXPORT, &desc->flags);
	mutex_unlock(&sysfs_lock);
	return 0;

fail_unregister_device:
	device_unregister(dev);
fail_unlock:
	mutex_unlock(&sysfs_lock);
817 818
	pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
		 status);
David Brownell's avatar
David Brownell committed
819 820
	return status;
}
821 822 823 824 825

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
826 827
EXPORT_SYMBOL_GPL(gpio_export);

828
static int match_export(struct device *dev, const void *data)
David Brownell's avatar
David Brownell committed
829 830 831 832
{
	return dev_get_drvdata(dev) == data;
}

833 834 835 836 837 838 839 840 841 842 843
/**
 * 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.
 */
844 845
static int gpiod_export_link(struct device *dev, const char *name,
			     struct gpio_desc *desc)
846 847 848
{
	int			status = -EINVAL;

849
	if (!desc)
850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869
		goto done;

	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);

done:
	if (status)
870 871
		pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
			 status);
872 873 874 875

	return status;
}

876 877 878 879 880
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);
881 882 883 884 885 886 887 888 889 890 891 892 893

/**
 * 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.
 */
894
static int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
895 896 897 898
{
	struct device		*dev = NULL;
	int			status = -EINVAL;

899
	if (!desc)
900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918
		goto done;

	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);

done:
	if (status)
919 920
		pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
			 status);
921 922 923

	return status;
}
924 925 926 927 928

int gpio_sysfs_set_active_low(unsigned gpio, int value)
{
	return gpiod_sysfs_set_active_low(gpio_to_desc(gpio), value);
}
929 930
EXPORT_SYMBOL_GPL(gpio_sysfs_set_active_low);

David Brownell's avatar
David Brownell committed
931 932 933 934 935 936
/**
 * gpio_unexport - reverse effect of gpio_export()
 * @gpio: gpio to make unavailable
 *
 * This is implicit on gpio_free().
 */
937
static void gpiod_unexport(struct gpio_desc *desc)
David Brownell's avatar
David Brownell committed
938
{
939
	int			status = 0;
940
	struct device		*dev = NULL;
David Brownell's avatar
David Brownell committed
941

942
	if (!desc) {
943
		status = -EINVAL;
David Brownell's avatar
David Brownell committed
944
		goto done;
945
	}
David Brownell's avatar
David Brownell committed
946 947 948 949 950 951 952

	mutex_lock(&sysfs_lock);

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

		dev = class_find_device(&gpio_class, NULL, desc, match_export);
		if (dev) {
953
			gpio_setup_irq(desc, dev, 0);
David Brownell's avatar
David Brownell committed
954 955 956 957 958 959
			clear_bit(FLAG_EXPORT, &desc->flags);
		} else
			status = -ENODEV;
	}

	mutex_unlock(&sysfs_lock);
960

961 962 963 964
	if (dev) {
		device_unregister(dev);
		put_device(dev);
	}
David Brownell's avatar
David Brownell committed
965 966
done:
	if (status)
967 968 969 970 971 972 973
		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
974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993
}
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);
994
	if (!IS_ERR(dev)) {
David Brownell's avatar
David Brownell committed
995 996 997
		status = sysfs_create_group(&dev->kobj,
				&gpiochip_attr_group);
	} else
998
		status = PTR_ERR(dev);
David Brownell's avatar
David Brownell committed
999 1000 1001 1002 1003 1004 1005 1006
	chip->exported = (status == 0);
	mutex_unlock(&sysfs_lock);

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

		spin_lock_irqsave(&gpio_lock, flags);
1007 1008 1009
		gpio = 0;
		while (gpio < chip->ngpio)
			chip->desc[gpio++].chip = NULL;
David Brownell's avatar
David Brownell committed
1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043
		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;
1044
	struct gpio_chip *chip;
David Brownell's avatar
David Brownell committed
1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056

	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);
1057
	list_for_each_entry(chip, &gpio_chips, list) {
David Brownell's avatar
David Brownell committed
1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081
		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)
{
}

1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102
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
1103 1104
#endif /* CONFIG_GPIO_SYSFS */

1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 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
/*
 * 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;
}

1142 1143 1144 1145 1146 1147 1148 1149
/**
 * 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.
1150
 *
David Brownell's avatar
David Brownell committed
1151 1152 1153 1154 1155
 * 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.
 *
1156 1157
 * If chip->base is negative, this requests dynamic assignment of
 * a range of valid GPIOs.
1158 1159 1160 1161 1162 1163
 */
int gpiochip_add(struct gpio_chip *chip)
{
	unsigned long	flags;
	int		status = 0;
	unsigned	id;
1164
	int		base = chip->base;
1165

Trent Piepho's avatar
Trent Piepho committed
1166
	if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
1167
			&& base >= 0) {
1168 1169 1170 1171 1172 1173
		status = -EINVAL;
		goto fail;
	}

	spin_lock_irqsave(&gpio_lock, flags);

1174 1175 1176 1177
	if (base < 0) {
		base = gpiochip_find_base(chip->ngpio);
		if (base < 0) {
			status = base;
David Brownell's avatar
David Brownell committed
1178
			goto unlock;
1179 1180 1181 1182
		}
		chip->base = base;
	}

1183 1184
	status = gpiochip_add_to_list(chip);

1185
	if (status == 0) {
1186 1187 1188 1189 1190
		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
1191 1192 1193 1194 1195

			/* 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,
1196
			 * and in case chip->get_direction is not set,
David Brownell's avatar
David Brownell committed
1197 1198
			 * we may expose the wrong direction in sysfs.
			 */
1199
			desc->flags = !chip->direction_input
David Brownell's avatar
David Brownell committed
1200 1201
				? (1 << FLAG_IS_OUT)
				: 0;
1202 1203 1204
		}
	}

1205 1206 1207 1208
#ifdef CONFIG_PINCTRL
	INIT_LIST_HEAD(&chip->pin_ranges);
#endif

1209 1210
	of_gpiochip_add(chip);

David Brownell's avatar
David Brownell committed
1211
unlock:
1212
	spin_unlock_irqrestore(&gpio_lock, flags);
1213 1214 1215 1216 1217 1218 1219 1220

	if (status)
		goto fail;

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

1221
	pr_debug("gpiochip_add: registered GPIOs %d to %d on device: %s\n",
1222 1223 1224
		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");

1225
	return 0;
1226 1227
fail:
	/* failures here can mean systems won't boot... */
1228 1229 1230
	pr_err("gpiochip_add: gpios %d..%d (%s) failed to register\n",
		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");
1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248
	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);

1249
	gpiochip_remove_pin_ranges(chip);
1250 1251
	of_gpiochip_remove(chip);

1252 1253
	for (id = 0; id < chip->ngpio; id++) {
		if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) {
1254 1255 1256 1257 1258
			status = -EBUSY;
			break;
		}
	}
	if (status == 0) {
1259 1260
		for (id = 0; id < chip->ngpio; id++)
			chip->desc[id].chip = NULL;
1261 1262

		list_del(&chip->list);
1263 1264 1265
	}

	spin_unlock_irqrestore(&gpio_lock, flags);
David Brownell's avatar
David Brownell committed
1266 1267 1268 1269

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

1270 1271 1272 1273
	return status;
}
EXPORT_SYMBOL_GPL(gpiochip_remove);

1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284
/**
 * 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.
 */
1285
struct gpio_chip *gpiochip_find(void *data,
1286
				int (*match)(struct gpio_chip *chip,
1287
					     void *data))
1288
{
1289
	struct gpio_chip *chip;
1290 1291 1292
	unsigned long flags;

	spin_lock_irqsave(&gpio_lock, flags);
1293 1294
	list_for_each_entry(chip, &gpio_chips, list)
		if (match(chip, data))
1295
			break;
1296 1297 1298 1299

	/* No match? */
	if (&chip->list == &gpio_chips)
		chip = NULL;
1300 1301 1302 1303
	spin_unlock_irqrestore(&gpio_lock, flags);

	return chip;
}
Jean Delvare's avatar
Jean Delvare committed
1304
EXPORT_SYMBOL_GPL(gpiochip_find);
1305

1306
#ifdef CONFIG_PINCTRL
1307

1308 1309 1310 1311
/**
 * gpiochip_add_pin_range() - add a range for GPIO <-> pin mapping
 * @chip: the gpiochip to add the range for
 * @pinctrl_name: the dev_name() of the pin controller to map to
1312 1313
 * @gpio_offset: the start offset in the current gpio_chip number space
 * @pin_offset: the start offset in the pin controller number space
1314 1315 1316
 * @npins: the number of pins from the offset of each pin space (GPIO and
 *	pin controller) to accumulate in this range
 */
1317
int gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
1318
			   unsigned int gpio_offset, unsigned int pin_offset,