1 #include <linux/kernel.h>
2 #include <linux/module.h>
4 #include <linux/spinlock.h>
5 #include <linux/device.h>
7 #include <linux/debugfs.h>
8 #include <linux/seq_file.h>
9 #include <linux/gpio.h>
12 /* Optional implementation infrastructure for GPIO interfaces.
14 * Platforms may want to use this if they tend to use very many GPIOs
15 * that aren't part of a System-On-Chip core; or across I2C/SPI/etc.
17 * When kernel footprint or instruction count is an issue, simpler
18 * implementations may be preferred. The GPIO programming interface
19 * allows for inlining speed-critical get/set operations for common
20 * cases, so that access to SOC-integrated GPIOs can sometimes cost
21 * only an instruction or two per bit.
25 /* When debugging, extend minimal trust to callers and platform code.
26 * Also emit diagnostic messages that may help initial bringup, when
27 * board setup or driver bugs are most common.
29 * Otherwise, minimize overhead in what may be bitbanging codepaths.
32 #define extra_checks 1
34 #define extra_checks 0
37 /* gpio_lock prevents conflicts during gpio_desc[] table updates.
38 * While any GPIO is requested, its gpio_chip is not removable;
39 * each GPIO's "requested" flag serves as a lock and refcount.
41 static DEFINE_SPINLOCK(gpio_lock);
44 struct gpio_chip *chip;
46 /* flag symbols are bit numbers */
47 #define FLAG_REQUESTED 0
49 #define FLAG_RESERVED 2
50 #define FLAG_EXPORT 3 /* protected by sysfs_lock */
51 #define FLAG_SYSFS 4 /* exported via /sys/class/gpio/control */
53 #ifdef CONFIG_DEBUG_FS
57 static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];
59 static inline void desc_set_label(struct gpio_desc *d, const char *label)
61 #ifdef CONFIG_DEBUG_FS
66 /* Warn when drivers omit gpio_request() calls -- legal but ill-advised
67 * when setting direction, and otherwise illegal. Until board setup code
68 * and drivers use explicit requests everywhere (which won't happen when
69 * those calls have no teeth) we can't avoid autorequesting. This nag
70 * message should motivate switching to explicit requests... so should
71 * the weaker cleanup after faults, compared to gpio_request().
73 static int gpio_ensure_requested(struct gpio_desc *desc, unsigned offset)
75 if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
76 struct gpio_chip *chip = desc->chip;
77 int gpio = chip->base + offset;
79 if (!try_module_get(chip->owner)) {
80 pr_err("GPIO-%d: module can't be gotten \n", gpio);
81 clear_bit(FLAG_REQUESTED, &desc->flags);
85 pr_warning("GPIO-%d autorequested\n", gpio);
86 desc_set_label(desc, "[auto]");
87 /* caller must chip->request() w/o spinlock */
94 /* caller holds gpio_lock *OR* gpio is marked as requested */
95 static inline struct gpio_chip *gpio_to_chip(unsigned gpio)
97 return gpio_desc[gpio].chip;
100 /* dynamic allocation of GPIOs, e.g. on a hotplugged device */
101 static int gpiochip_find_base(int ngpio)
107 for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) {
108 struct gpio_desc *desc = &gpio_desc[i];
109 struct gpio_chip *chip = desc->chip;
111 if (!chip && !test_bit(FLAG_RESERVED, &desc->flags)) {
113 if (spare == ngpio) {
120 i -= chip->ngpio - 1;
124 if (gpio_is_valid(base))
125 pr_debug("%s: found new base at %d\n", __func__, base);
130 * gpiochip_reserve() - reserve range of gpios to use with platform code only
131 * @start: starting gpio number
132 * @ngpio: number of gpios to reserve
133 * Context: platform init, potentially before irqs or kmalloc will work
135 * Returns a negative errno if any gpio within the range is already reserved
136 * or registered, else returns zero as a success code. Use this function
137 * to mark a range of gpios as unavailable for dynamic gpio number allocation,
138 * for example because its driver support is not yet loaded.
140 int __init gpiochip_reserve(int start, int ngpio)
146 if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio - 1))
149 spin_lock_irqsave(&gpio_lock, flags);
151 for (i = start; i < start + ngpio; i++) {
152 struct gpio_desc *desc = &gpio_desc[i];
154 if (desc->chip || test_bit(FLAG_RESERVED, &desc->flags)) {
159 set_bit(FLAG_RESERVED, &desc->flags);
162 pr_debug("%s: reserved gpios from %d to %d\n",
163 __func__, start, start + ngpio - 1);
165 spin_unlock_irqrestore(&gpio_lock, flags);
170 #ifdef CONFIG_GPIO_SYSFS
172 /* lock protects against unexport_gpio() being called while
173 * sysfs files are active.
175 static DEFINE_MUTEX(sysfs_lock);
178 * /sys/class/gpio/gpioN... only for GPIOs that are exported
180 * * MAY BE OMITTED if kernel won't allow direction changes
181 * * is read/write as "in" or "out"
182 * * may also be written as "high" or "low", initializing
183 * output value as specified ("out" implies "low")
185 * * always readable, subject to hardware behavior
186 * * may be writable, as zero/nonzero
188 * REVISIT there will likely be an attribute for configuring async
189 * notifications, e.g. to specify polling interval or IRQ trigger type
190 * that would for example trigger a poll() on the "value".
193 static ssize_t gpio_direction_show(struct device *dev,
194 struct device_attribute *attr, char *buf)
196 const struct gpio_desc *desc = dev_get_drvdata(dev);
199 mutex_lock(&sysfs_lock);
201 if (!test_bit(FLAG_EXPORT, &desc->flags))
204 status = sprintf(buf, "%s\n",
205 test_bit(FLAG_IS_OUT, &desc->flags)
208 mutex_unlock(&sysfs_lock);
212 static ssize_t gpio_direction_store(struct device *dev,
213 struct device_attribute *attr, const char *buf, size_t size)
215 const struct gpio_desc *desc = dev_get_drvdata(dev);
216 unsigned gpio = desc - gpio_desc;
219 mutex_lock(&sysfs_lock);
221 if (!test_bit(FLAG_EXPORT, &desc->flags))
223 else if (sysfs_streq(buf, "high"))
224 status = gpio_direction_output(gpio, 1);
225 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
226 status = gpio_direction_output(gpio, 0);
227 else if (sysfs_streq(buf, "in"))
228 status = gpio_direction_input(gpio);
232 mutex_unlock(&sysfs_lock);
233 return status ? : size;
236 static const DEVICE_ATTR(direction, 0644,
237 gpio_direction_show, gpio_direction_store);
239 static ssize_t gpio_value_show(struct device *dev,
240 struct device_attribute *attr, char *buf)
242 const struct gpio_desc *desc = dev_get_drvdata(dev);
243 unsigned gpio = desc - gpio_desc;
246 mutex_lock(&sysfs_lock);
248 if (!test_bit(FLAG_EXPORT, &desc->flags))
251 status = sprintf(buf, "%d\n", !!gpio_get_value_cansleep(gpio));
253 mutex_unlock(&sysfs_lock);
257 static ssize_t gpio_value_store(struct device *dev,
258 struct device_attribute *attr, const char *buf, size_t size)
260 const struct gpio_desc *desc = dev_get_drvdata(dev);
261 unsigned gpio = desc - gpio_desc;
264 mutex_lock(&sysfs_lock);
266 if (!test_bit(FLAG_EXPORT, &desc->flags))
268 else if (!test_bit(FLAG_IS_OUT, &desc->flags))
273 status = strict_strtol(buf, 0, &value);
275 gpio_set_value_cansleep(gpio, value != 0);
280 mutex_unlock(&sysfs_lock);
284 static /*const*/ DEVICE_ATTR(value, 0644,
285 gpio_value_show, gpio_value_store);
287 static const struct attribute *gpio_attrs[] = {
288 &dev_attr_direction.attr,
289 &dev_attr_value.attr,
293 static const struct attribute_group gpio_attr_group = {
294 .attrs = (struct attribute **) gpio_attrs,
298 * /sys/class/gpio/gpiochipN/
299 * /base ... matching gpio_chip.base (N)
300 * /label ... matching gpio_chip.label
301 * /ngpio ... matching gpio_chip.ngpio
304 static ssize_t chip_base_show(struct device *dev,
305 struct device_attribute *attr, char *buf)
307 const struct gpio_chip *chip = dev_get_drvdata(dev);
309 return sprintf(buf, "%d\n", chip->base);
311 static DEVICE_ATTR(base, 0444, chip_base_show, NULL);
313 static ssize_t chip_label_show(struct device *dev,
314 struct device_attribute *attr, char *buf)
316 const struct gpio_chip *chip = dev_get_drvdata(dev);
318 return sprintf(buf, "%s\n", chip->label ? : "");
320 static DEVICE_ATTR(label, 0444, chip_label_show, NULL);
322 static ssize_t chip_ngpio_show(struct device *dev,
323 struct device_attribute *attr, char *buf)
325 const struct gpio_chip *chip = dev_get_drvdata(dev);
327 return sprintf(buf, "%u\n", chip->ngpio);
329 static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL);
331 static const struct attribute *gpiochip_attrs[] = {
333 &dev_attr_label.attr,
334 &dev_attr_ngpio.attr,
338 static const struct attribute_group gpiochip_attr_group = {
339 .attrs = (struct attribute **) gpiochip_attrs,
343 * /sys/class/gpio/export ... write-only
344 * integer N ... number of GPIO to export (full access)
345 * /sys/class/gpio/unexport ... write-only
346 * integer N ... number of GPIO to unexport
348 static ssize_t export_store(struct class *class, const char *buf, size_t len)
353 status = strict_strtol(buf, 0, &gpio);
357 /* No extra locking here; FLAG_SYSFS just signifies that the
358 * request and export were done by on behalf of userspace, so
359 * they may be undone on its behalf too.
362 status = gpio_request(gpio, "sysfs");
366 status = gpio_export(gpio, true);
370 set_bit(FLAG_SYSFS, &gpio_desc[gpio].flags);
374 pr_debug("%s: status %d\n", __func__, status);
375 return status ? : len;
378 static ssize_t unexport_store(struct class *class, const char *buf, size_t len)
383 status = strict_strtol(buf, 0, &gpio);
389 /* reject bogus commands (gpio_unexport ignores them) */
390 if (!gpio_is_valid(gpio))
393 /* No extra locking here; FLAG_SYSFS just signifies that the
394 * request and export were done by on behalf of userspace, so
395 * they may be undone on its behalf too.
397 if (test_and_clear_bit(FLAG_SYSFS, &gpio_desc[gpio].flags)) {
403 pr_debug("%s: status %d\n", __func__, status);
404 return status ? : len;
407 static struct class_attribute gpio_class_attrs[] = {
408 __ATTR(export, 0200, NULL, export_store),
409 __ATTR(unexport, 0200, NULL, unexport_store),
413 static struct class gpio_class = {
415 .owner = THIS_MODULE,
417 .class_attrs = gpio_class_attrs,
422 * gpio_export - export a GPIO through sysfs
423 * @gpio: gpio to make available, already requested
424 * @direction_may_change: true if userspace may change gpio direction
425 * Context: arch_initcall or later
427 * When drivers want to make a GPIO accessible to userspace after they
428 * have requested it -- perhaps while debugging, or as part of their
429 * public interface -- they may use this routine. If the GPIO can
430 * change direction (some can't) and the caller allows it, userspace
431 * will see "direction" sysfs attribute which may be used to change
432 * the gpio's direction. A "value" attribute will always be provided.
434 * Returns zero on success, else an error.
436 int gpio_export(unsigned gpio, bool direction_may_change)
439 struct gpio_desc *desc;
440 int status = -EINVAL;
443 /* can't export until sysfs is available ... */
445 pr_debug("%s: called too early!\n", __func__);
449 if (!gpio_is_valid(gpio))
452 mutex_lock(&sysfs_lock);
454 spin_lock_irqsave(&gpio_lock, flags);
455 desc = &gpio_desc[gpio];
456 if (test_bit(FLAG_REQUESTED, &desc->flags)
457 && !test_bit(FLAG_EXPORT, &desc->flags)) {
459 if (!desc->chip->direction_input
460 || !desc->chip->direction_output)
461 direction_may_change = false;
463 spin_unlock_irqrestore(&gpio_lock, flags);
465 if (desc->chip->names && desc->chip->names[gpio - desc->chip->base])
466 ioname = desc->chip->names[gpio - desc->chip->base];
471 dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
472 desc, ioname ? ioname : "gpio%d", gpio);
474 if (direction_may_change)
475 status = sysfs_create_group(&dev->kobj,
478 status = device_create_file(dev,
481 device_unregister(dev);
485 set_bit(FLAG_EXPORT, &desc->flags);
488 mutex_unlock(&sysfs_lock);
492 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
496 EXPORT_SYMBOL_GPL(gpio_export);
498 static int match_export(struct device *dev, void *data)
500 return dev_get_drvdata(dev) == data;
504 * gpio_unexport - reverse effect of gpio_export()
505 * @gpio: gpio to make unavailable
507 * This is implicit on gpio_free().
509 void gpio_unexport(unsigned gpio)
511 struct gpio_desc *desc;
512 int status = -EINVAL;
514 if (!gpio_is_valid(gpio))
517 mutex_lock(&sysfs_lock);
519 desc = &gpio_desc[gpio];
521 if (test_bit(FLAG_EXPORT, &desc->flags)) {
522 struct device *dev = NULL;
524 dev = class_find_device(&gpio_class, NULL, desc, match_export);
526 clear_bit(FLAG_EXPORT, &desc->flags);
528 device_unregister(dev);
534 mutex_unlock(&sysfs_lock);
537 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
539 EXPORT_SYMBOL_GPL(gpio_unexport);
541 static int gpiochip_export(struct gpio_chip *chip)
546 /* Many systems register gpio chips for SOC support very early,
547 * before driver model support is available. In those cases we
548 * export this later, in gpiolib_sysfs_init() ... here we just
549 * verify that _some_ field of gpio_class got initialized.
554 /* use chip->base for the ID; it's already known to be unique */
555 mutex_lock(&sysfs_lock);
556 dev = device_create(&gpio_class, chip->dev, MKDEV(0, 0), chip,
557 "gpiochip%d", chip->base);
559 status = sysfs_create_group(&dev->kobj,
560 &gpiochip_attr_group);
563 chip->exported = (status == 0);
564 mutex_unlock(&sysfs_lock);
570 spin_lock_irqsave(&gpio_lock, flags);
572 while (gpio_desc[gpio].chip == chip)
573 gpio_desc[gpio++].chip = NULL;
574 spin_unlock_irqrestore(&gpio_lock, flags);
576 pr_debug("%s: chip %s status %d\n", __func__,
577 chip->label, status);
583 static void gpiochip_unexport(struct gpio_chip *chip)
588 mutex_lock(&sysfs_lock);
589 dev = class_find_device(&gpio_class, NULL, chip, match_export);
592 device_unregister(dev);
597 mutex_unlock(&sysfs_lock);
600 pr_debug("%s: chip %s status %d\n", __func__,
601 chip->label, status);
604 static int __init gpiolib_sysfs_init(void)
610 status = class_register(&gpio_class);
614 /* Scan and register the gpio_chips which registered very
615 * early (e.g. before the class_register above was called).
617 * We run before arch_initcall() so chip->dev nodes can have
618 * registered, and so arch_initcall() can always gpio_export().
620 spin_lock_irqsave(&gpio_lock, flags);
621 for (gpio = 0; gpio < ARCH_NR_GPIOS; gpio++) {
622 struct gpio_chip *chip;
624 chip = gpio_desc[gpio].chip;
625 if (!chip || chip->exported)
628 spin_unlock_irqrestore(&gpio_lock, flags);
629 status = gpiochip_export(chip);
630 spin_lock_irqsave(&gpio_lock, flags);
632 spin_unlock_irqrestore(&gpio_lock, flags);
637 postcore_initcall(gpiolib_sysfs_init);
640 static inline int gpiochip_export(struct gpio_chip *chip)
645 static inline void gpiochip_unexport(struct gpio_chip *chip)
649 #endif /* CONFIG_GPIO_SYSFS */
652 * gpiochip_add() - register a gpio_chip
653 * @chip: the chip to register, with chip->base initialized
654 * Context: potentially before irqs or kmalloc will work
656 * Returns a negative errno if the chip can't be registered, such as
657 * because the chip->base is invalid or already associated with a
658 * different chip. Otherwise it returns zero as a success code.
660 * When gpiochip_add() is called very early during boot, so that GPIOs
661 * can be freely used, the chip->dev device must be registered before
662 * the gpio framework's arch_initcall(). Otherwise sysfs initialization
663 * for GPIOs will fail rudely.
665 * If chip->base is negative, this requests dynamic assignment of
666 * a range of valid GPIOs.
668 int gpiochip_add(struct gpio_chip *chip)
673 int base = chip->base;
675 if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
681 spin_lock_irqsave(&gpio_lock, flags);
684 base = gpiochip_find_base(chip->ngpio);
692 /* these GPIO numbers must not be managed by another gpio_chip */
693 for (id = base; id < base + chip->ngpio; id++) {
694 if (gpio_desc[id].chip != NULL) {
700 for (id = base; id < base + chip->ngpio; id++) {
701 gpio_desc[id].chip = chip;
703 /* REVISIT: most hardware initializes GPIOs as
704 * inputs (often with pullups enabled) so power
705 * usage is minimized. Linux code should set the
706 * gpio direction first thing; but until it does,
707 * we may expose the wrong direction in sysfs.
709 gpio_desc[id].flags = !chip->direction_input
716 spin_unlock_irqrestore(&gpio_lock, flags);
718 status = gpiochip_export(chip);
720 /* failures here can mean systems won't boot... */
722 pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n",
723 chip->base, chip->base + chip->ngpio - 1,
724 chip->label ? : "generic");
727 EXPORT_SYMBOL_GPL(gpiochip_add);
730 * gpiochip_remove() - unregister a gpio_chip
731 * @chip: the chip to unregister
733 * A gpio_chip with any GPIOs still requested may not be removed.
735 int gpiochip_remove(struct gpio_chip *chip)
741 spin_lock_irqsave(&gpio_lock, flags);
743 for (id = chip->base; id < chip->base + chip->ngpio; id++) {
744 if (test_bit(FLAG_REQUESTED, &gpio_desc[id].flags)) {
750 for (id = chip->base; id < chip->base + chip->ngpio; id++)
751 gpio_desc[id].chip = NULL;
754 spin_unlock_irqrestore(&gpio_lock, flags);
757 gpiochip_unexport(chip);
761 EXPORT_SYMBOL_GPL(gpiochip_remove);
764 /* These "optional" allocation calls help prevent drivers from stomping
765 * on each other, and help provide better diagnostics in debugfs.
766 * They're called even less than the "set direction" calls.
768 int gpio_request(unsigned gpio, const char *label)
770 struct gpio_desc *desc;
771 struct gpio_chip *chip;
772 int status = -EINVAL;
775 spin_lock_irqsave(&gpio_lock, flags);
777 if (!gpio_is_valid(gpio))
779 desc = &gpio_desc[gpio];
784 if (!try_module_get(chip->owner))
787 /* NOTE: gpio_request() can be called in early boot,
788 * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
791 if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
792 desc_set_label(desc, label ? : "?");
796 module_put(chip->owner);
801 /* chip->request may sleep */
802 spin_unlock_irqrestore(&gpio_lock, flags);
803 status = chip->request(chip, gpio - chip->base);
804 spin_lock_irqsave(&gpio_lock, flags);
807 desc_set_label(desc, NULL);
808 module_put(chip->owner);
809 clear_bit(FLAG_REQUESTED, &desc->flags);
815 pr_debug("gpio_request: gpio-%d (%s) status %d\n",
816 gpio, label ? : "?", status);
817 spin_unlock_irqrestore(&gpio_lock, flags);
820 EXPORT_SYMBOL_GPL(gpio_request);
822 void gpio_free(unsigned gpio)
825 struct gpio_desc *desc;
826 struct gpio_chip *chip;
830 if (!gpio_is_valid(gpio)) {
831 WARN_ON(extra_checks);
837 spin_lock_irqsave(&gpio_lock, flags);
839 desc = &gpio_desc[gpio];
841 if (chip && test_bit(FLAG_REQUESTED, &desc->flags)) {
843 spin_unlock_irqrestore(&gpio_lock, flags);
844 might_sleep_if(extra_checks && chip->can_sleep);
845 chip->free(chip, gpio - chip->base);
846 spin_lock_irqsave(&gpio_lock, flags);
848 desc_set_label(desc, NULL);
849 module_put(desc->chip->owner);
850 clear_bit(FLAG_REQUESTED, &desc->flags);
852 WARN_ON(extra_checks);
854 spin_unlock_irqrestore(&gpio_lock, flags);
856 EXPORT_SYMBOL_GPL(gpio_free);
860 * gpiochip_is_requested - return string iff signal was requested
861 * @chip: controller managing the signal
862 * @offset: of signal within controller's 0..(ngpio - 1) range
864 * Returns NULL if the GPIO is not currently requested, else a string.
865 * If debugfs support is enabled, the string returned is the label passed
866 * to gpio_request(); otherwise it is a meaningless constant.
868 * This function is for use by GPIO controller drivers. The label can
869 * help with diagnostics, and knowing that the signal is used as a GPIO
870 * can help avoid accidentally multiplexing it to another controller.
872 const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
874 unsigned gpio = chip->base + offset;
876 if (!gpio_is_valid(gpio) || gpio_desc[gpio].chip != chip)
878 if (test_bit(FLAG_REQUESTED, &gpio_desc[gpio].flags) == 0)
880 #ifdef CONFIG_DEBUG_FS
881 return gpio_desc[gpio].label;
886 EXPORT_SYMBOL_GPL(gpiochip_is_requested);
889 /* Drivers MUST set GPIO direction before making get/set calls. In
890 * some cases this is done in early boot, before IRQs are enabled.
892 * As a rule these aren't called more than once (except for drivers
893 * using the open-drain emulation idiom) so these are natural places
894 * to accumulate extra debugging checks. Note that we can't (yet)
895 * rely on gpio_request() having been called beforehand.
898 int gpio_direction_input(unsigned gpio)
901 struct gpio_chip *chip;
902 struct gpio_desc *desc = &gpio_desc[gpio];
903 int status = -EINVAL;
905 spin_lock_irqsave(&gpio_lock, flags);
907 if (!gpio_is_valid(gpio))
910 if (!chip || !chip->get || !chip->direction_input)
913 if (gpio >= chip->ngpio)
915 status = gpio_ensure_requested(desc, gpio);
919 /* now we know the gpio is valid and chip won't vanish */
921 spin_unlock_irqrestore(&gpio_lock, flags);
923 might_sleep_if(extra_checks && chip->can_sleep);
926 status = chip->request(chip, gpio);
928 pr_debug("GPIO-%d: chip request fail, %d\n",
929 chip->base + gpio, status);
930 /* and it's not available to anyone else ...
931 * gpio_request() is the fully clean solution.
937 status = chip->direction_input(chip, gpio);
939 clear_bit(FLAG_IS_OUT, &desc->flags);
943 spin_unlock_irqrestore(&gpio_lock, flags);
945 pr_debug("%s: gpio-%d status %d\n",
946 __func__, gpio, status);
949 EXPORT_SYMBOL_GPL(gpio_direction_input);
951 int gpio_direction_output(unsigned gpio, int value)
954 struct gpio_chip *chip;
955 struct gpio_desc *desc = &gpio_desc[gpio];
956 int status = -EINVAL;
958 spin_lock_irqsave(&gpio_lock, flags);
960 if (!gpio_is_valid(gpio))
963 if (!chip || !chip->set || !chip->direction_output)
966 if (gpio >= chip->ngpio)
968 status = gpio_ensure_requested(desc, gpio);
972 /* now we know the gpio is valid and chip won't vanish */
974 spin_unlock_irqrestore(&gpio_lock, flags);
976 might_sleep_if(extra_checks && chip->can_sleep);
979 status = chip->request(chip, gpio);
981 pr_debug("GPIO-%d: chip request fail, %d\n",
982 chip->base + gpio, status);
983 /* and it's not available to anyone else ...
984 * gpio_request() is the fully clean solution.
990 status = chip->direction_output(chip, gpio, value);
992 set_bit(FLAG_IS_OUT, &desc->flags);
996 spin_unlock_irqrestore(&gpio_lock, flags);
998 pr_debug("%s: gpio-%d status %d\n",
999 __func__, gpio, status);
1002 EXPORT_SYMBOL_GPL(gpio_direction_output);
1005 /* I/O calls are only valid after configuration completed; the relevant
1006 * "is this a valid GPIO" error checks should already have been done.
1008 * "Get" operations are often inlinable as reading a pin value register,
1009 * and masking the relevant bit in that register.
1011 * When "set" operations are inlinable, they involve writing that mask to
1012 * one register to set a low value, or a different register to set it high.
1013 * Otherwise locking is needed, so there may be little value to inlining.
1015 *------------------------------------------------------------------------
1017 * IMPORTANT!!! The hot paths -- get/set value -- assume that callers
1018 * have requested the GPIO. That can include implicit requesting by
1019 * a direction setting call. Marking a gpio as requested locks its chip
1020 * in memory, guaranteeing that these table lookups need no more locking
1021 * and that gpiochip_remove() will fail.
1023 * REVISIT when debugging, consider adding some instrumentation to ensure
1024 * that the GPIO was actually requested.
1028 * __gpio_get_value() - return a gpio's value
1029 * @gpio: gpio whose value will be returned
1032 * This is used directly or indirectly to implement gpio_get_value().
1033 * It returns the zero or nonzero value provided by the associated
1034 * gpio_chip.get() method; or zero if no such method is provided.
1036 int __gpio_get_value(unsigned gpio)
1038 struct gpio_chip *chip;
1040 chip = gpio_to_chip(gpio);
1041 WARN_ON(extra_checks && chip->can_sleep);
1042 return chip->get ? chip->get(chip, gpio - chip->base) : 0;
1044 EXPORT_SYMBOL_GPL(__gpio_get_value);
1047 * __gpio_set_value() - assign a gpio's value
1048 * @gpio: gpio whose value will be assigned
1049 * @value: value to assign
1052 * This is used directly or indirectly to implement gpio_set_value().
1053 * It invokes the associated gpio_chip.set() method.
1055 void __gpio_set_value(unsigned gpio, int value)
1057 struct gpio_chip *chip;
1059 chip = gpio_to_chip(gpio);
1060 WARN_ON(extra_checks && chip->can_sleep);
1061 chip->set(chip, gpio - chip->base, value);
1063 EXPORT_SYMBOL_GPL(__gpio_set_value);
1066 * __gpio_cansleep() - report whether gpio value access will sleep
1067 * @gpio: gpio in question
1070 * This is used directly or indirectly to implement gpio_cansleep(). It
1071 * returns nonzero if access reading or writing the GPIO value can sleep.
1073 int __gpio_cansleep(unsigned gpio)
1075 struct gpio_chip *chip;
1077 /* only call this on GPIOs that are valid! */
1078 chip = gpio_to_chip(gpio);
1080 return chip->can_sleep;
1082 EXPORT_SYMBOL_GPL(__gpio_cansleep);
1085 * __gpio_to_irq() - return the IRQ corresponding to a GPIO
1086 * @gpio: gpio whose IRQ will be returned (already requested)
1089 * This is used directly or indirectly to implement gpio_to_irq().
1090 * It returns the number of the IRQ signaled by this (input) GPIO,
1091 * or a negative errno.
1093 int __gpio_to_irq(unsigned gpio)
1095 struct gpio_chip *chip;
1097 chip = gpio_to_chip(gpio);
1098 return chip->to_irq ? chip->to_irq(chip, gpio - chip->base) : -ENXIO;
1100 EXPORT_SYMBOL_GPL(__gpio_to_irq);
1104 /* There's no value in making it easy to inline GPIO calls that may sleep.
1105 * Common examples include ones connected to I2C or SPI chips.
1108 int gpio_get_value_cansleep(unsigned gpio)
1110 struct gpio_chip *chip;
1112 might_sleep_if(extra_checks);
1113 chip = gpio_to_chip(gpio);
1114 return chip->get ? chip->get(chip, gpio - chip->base) : 0;
1116 EXPORT_SYMBOL_GPL(gpio_get_value_cansleep);
1118 void gpio_set_value_cansleep(unsigned gpio, int value)
1120 struct gpio_chip *chip;
1122 might_sleep_if(extra_checks);
1123 chip = gpio_to_chip(gpio);
1124 chip->set(chip, gpio - chip->base, value);
1126 EXPORT_SYMBOL_GPL(gpio_set_value_cansleep);
1129 #ifdef CONFIG_DEBUG_FS
1131 static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
1134 unsigned gpio = chip->base;
1135 struct gpio_desc *gdesc = &gpio_desc[gpio];
1138 for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) {
1139 if (!test_bit(FLAG_REQUESTED, &gdesc->flags))
1142 is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
1143 seq_printf(s, " gpio-%-3d (%-20.20s) %s %s",
1145 is_out ? "out" : "in ",
1147 ? (chip->get(chip, i) ? "hi" : "lo")
1151 int irq = gpio_to_irq(gpio);
1152 struct irq_desc *desc = irq_to_desc(irq);
1154 /* This races with request_irq(), set_irq_type(),
1155 * and set_irq_wake() ... but those are "rare".
1157 * More significantly, trigger type flags aren't
1158 * currently maintained by genirq.
1160 if (irq >= 0 && desc->action) {
1163 switch (desc->status & IRQ_TYPE_SENSE_MASK) {
1165 trigger = "(default)";
1167 case IRQ_TYPE_EDGE_FALLING:
1168 trigger = "edge-falling";
1170 case IRQ_TYPE_EDGE_RISING:
1171 trigger = "edge-rising";
1173 case IRQ_TYPE_EDGE_BOTH:
1174 trigger = "edge-both";
1176 case IRQ_TYPE_LEVEL_HIGH:
1177 trigger = "level-high";
1179 case IRQ_TYPE_LEVEL_LOW:
1180 trigger = "level-low";
1183 trigger = "?trigger?";
1187 seq_printf(s, " irq-%d %s%s",
1189 (desc->status & IRQ_WAKEUP)
1194 seq_printf(s, "\n");
1198 static int gpiolib_show(struct seq_file *s, void *unused)
1200 struct gpio_chip *chip = NULL;
1204 /* REVISIT this isn't locked against gpio_chip removal ... */
1206 for (gpio = 0; gpio_is_valid(gpio); gpio++) {
1209 if (chip == gpio_desc[gpio].chip)
1211 chip = gpio_desc[gpio].chip;
1215 seq_printf(s, "%sGPIOs %d-%d",
1216 started ? "\n" : "",
1217 chip->base, chip->base + chip->ngpio - 1);
1220 seq_printf(s, ", %s/%s",
1221 dev->bus ? dev->bus->name : "no-bus",
1224 seq_printf(s, ", %s", chip->label);
1225 if (chip->can_sleep)
1226 seq_printf(s, ", can sleep");
1227 seq_printf(s, ":\n");
1231 chip->dbg_show(s, chip);
1233 gpiolib_dbg_show(s, chip);
1238 static int gpiolib_open(struct inode *inode, struct file *file)
1240 return single_open(file, gpiolib_show, NULL);
1243 static struct file_operations gpiolib_operations = {
1244 .open = gpiolib_open,
1246 .llseek = seq_lseek,
1247 .release = single_release,
1250 static int __init gpiolib_debugfs_init(void)
1252 /* /sys/kernel/debug/gpio */
1253 (void) debugfs_create_file("gpio", S_IFREG | S_IRUGO,
1254 NULL, NULL, &gpiolib_operations);
1257 subsys_initcall(gpiolib_debugfs_init);
1259 #endif /* DEBUG_FS */