1 #include <linux/kernel.h>
2 #include <linux/module.h>
3 #include <linux/interrupt.h>
5 #include <linux/spinlock.h>
6 #include <linux/device.h>
8 #include <linux/debugfs.h>
9 #include <linux/seq_file.h>
10 #include <linux/gpio.h>
11 #include <linux/of_gpio.h>
12 #include <linux/idr.h>
13 #include <linux/slab.h>
15 #define CREATE_TRACE_POINTS
16 #include <trace/events/gpio.h>
18 /* Optional implementation infrastructure for GPIO interfaces.
20 * Platforms may want to use this if they tend to use very many GPIOs
21 * that aren't part of a System-On-Chip core; or across I2C/SPI/etc.
23 * When kernel footprint or instruction count is an issue, simpler
24 * implementations may be preferred. The GPIO programming interface
25 * allows for inlining speed-critical get/set operations for common
26 * cases, so that access to SOC-integrated GPIOs can sometimes cost
27 * only an instruction or two per bit.
31 /* When debugging, extend minimal trust to callers and platform code.
32 * Also emit diagnostic messages that may help initial bringup, when
33 * board setup or driver bugs are most common.
35 * Otherwise, minimize overhead in what may be bitbanging codepaths.
38 #define extra_checks 1
40 #define extra_checks 0
43 /* gpio_lock prevents conflicts during gpio_desc[] table updates.
44 * While any GPIO is requested, its gpio_chip is not removable;
45 * each GPIO's "requested" flag serves as a lock and refcount.
47 static DEFINE_SPINLOCK(gpio_lock);
50 struct gpio_chip *chip;
52 /* flag symbols are bit numbers */
53 #define FLAG_REQUESTED 0
55 #define FLAG_RESERVED 2
56 #define FLAG_EXPORT 3 /* protected by sysfs_lock */
57 #define FLAG_SYSFS 4 /* exported via /sys/class/gpio/control */
58 #define FLAG_TRIG_FALL 5 /* trigger on falling edge */
59 #define FLAG_TRIG_RISE 6 /* trigger on rising edge */
60 #define FLAG_ACTIVE_LOW 7 /* sysfs value has active low */
62 #define ID_SHIFT 16 /* add new flags before this one */
64 #define GPIO_FLAGS_MASK ((1 << ID_SHIFT) - 1)
65 #define GPIO_TRIGGER_MASK (BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE))
67 #ifdef CONFIG_DEBUG_FS
71 static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];
73 #ifdef CONFIG_GPIO_SYSFS
74 static DEFINE_IDR(dirent_idr);
77 static inline void desc_set_label(struct gpio_desc *d, const char *label)
79 #ifdef CONFIG_DEBUG_FS
84 /* Warn when drivers omit gpio_request() calls -- legal but ill-advised
85 * when setting direction, and otherwise illegal. Until board setup code
86 * and drivers use explicit requests everywhere (which won't happen when
87 * those calls have no teeth) we can't avoid autorequesting. This nag
88 * message should motivate switching to explicit requests... so should
89 * the weaker cleanup after faults, compared to gpio_request().
91 * NOTE: the autorequest mechanism is going away; at this point it's
92 * only "legal" in the sense that (old) code using it won't break yet,
93 * but instead only triggers a WARN() stack dump.
95 static int gpio_ensure_requested(struct gpio_desc *desc, unsigned offset)
97 const struct gpio_chip *chip = desc->chip;
98 const int gpio = chip->base + offset;
100 if (WARN(test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0,
101 "autorequest GPIO-%d\n", gpio)) {
102 if (!try_module_get(chip->owner)) {
103 pr_err("GPIO-%d: module can't be gotten \n", gpio);
104 clear_bit(FLAG_REQUESTED, &desc->flags);
108 desc_set_label(desc, "[auto]");
109 /* caller must chip->request() w/o spinlock */
116 /* caller holds gpio_lock *OR* gpio is marked as requested */
117 static inline struct gpio_chip *gpio_to_chip(unsigned gpio)
119 return gpio_desc[gpio].chip;
122 /* dynamic allocation of GPIOs, e.g. on a hotplugged device */
123 static int gpiochip_find_base(int ngpio)
129 for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) {
130 struct gpio_desc *desc = &gpio_desc[i];
131 struct gpio_chip *chip = desc->chip;
133 if (!chip && !test_bit(FLAG_RESERVED, &desc->flags)) {
135 if (spare == ngpio) {
142 i -= chip->ngpio - 1;
146 if (gpio_is_valid(base))
147 pr_debug("%s: found new base at %d\n", __func__, base);
152 * gpiochip_reserve() - reserve range of gpios to use with platform code only
153 * @start: starting gpio number
154 * @ngpio: number of gpios to reserve
155 * Context: platform init, potentially before irqs or kmalloc will work
157 * Returns a negative errno if any gpio within the range is already reserved
158 * or registered, else returns zero as a success code. Use this function
159 * to mark a range of gpios as unavailable for dynamic gpio number allocation,
160 * for example because its driver support is not yet loaded.
162 int __init gpiochip_reserve(int start, int ngpio)
168 if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio - 1))
171 spin_lock_irqsave(&gpio_lock, flags);
173 for (i = start; i < start + ngpio; i++) {
174 struct gpio_desc *desc = &gpio_desc[i];
176 if (desc->chip || test_bit(FLAG_RESERVED, &desc->flags)) {
181 set_bit(FLAG_RESERVED, &desc->flags);
184 pr_debug("%s: reserved gpios from %d to %d\n",
185 __func__, start, start + ngpio - 1);
187 spin_unlock_irqrestore(&gpio_lock, flags);
192 #ifdef CONFIG_GPIO_SYSFS
194 /* lock protects against unexport_gpio() being called while
195 * sysfs files are active.
197 static DEFINE_MUTEX(sysfs_lock);
200 * /sys/class/gpio/gpioN... only for GPIOs that are exported
202 * * MAY BE OMITTED if kernel won't allow direction changes
203 * * is read/write as "in" or "out"
204 * * may also be written as "high" or "low", initializing
205 * output value as specified ("out" implies "low")
207 * * always readable, subject to hardware behavior
208 * * may be writable, as zero/nonzero
210 * * configures behavior of poll(2) on /value
211 * * available only if pin can generate IRQs on input
212 * * is read/write as "none", "falling", "rising", or "both"
214 * * configures polarity of /value
215 * * is read/write as zero/nonzero
216 * * also affects existing and subsequent "falling" and "rising"
217 * /edge configuration
220 static ssize_t gpio_direction_show(struct device *dev,
221 struct device_attribute *attr, char *buf)
223 const struct gpio_desc *desc = dev_get_drvdata(dev);
226 mutex_lock(&sysfs_lock);
228 if (!test_bit(FLAG_EXPORT, &desc->flags))
231 status = sprintf(buf, "%s\n",
232 test_bit(FLAG_IS_OUT, &desc->flags)
235 mutex_unlock(&sysfs_lock);
239 static ssize_t gpio_direction_store(struct device *dev,
240 struct device_attribute *attr, const char *buf, size_t size)
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))
250 else if (sysfs_streq(buf, "high"))
251 status = gpio_direction_output(gpio, 1);
252 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
253 status = gpio_direction_output(gpio, 0);
254 else if (sysfs_streq(buf, "in"))
255 status = gpio_direction_input(gpio);
259 mutex_unlock(&sysfs_lock);
260 return status ? : size;
263 static /* const */ DEVICE_ATTR(direction, 0644,
264 gpio_direction_show, gpio_direction_store);
266 static ssize_t gpio_value_show(struct device *dev,
267 struct device_attribute *attr, char *buf)
269 const struct gpio_desc *desc = dev_get_drvdata(dev);
270 unsigned gpio = desc - gpio_desc;
273 mutex_lock(&sysfs_lock);
275 if (!test_bit(FLAG_EXPORT, &desc->flags)) {
280 value = !!gpio_get_value_cansleep(gpio);
281 if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
284 status = sprintf(buf, "%d\n", value);
287 mutex_unlock(&sysfs_lock);
291 static ssize_t gpio_value_store(struct device *dev,
292 struct device_attribute *attr, const char *buf, size_t size)
294 const struct gpio_desc *desc = dev_get_drvdata(dev);
295 unsigned gpio = desc - gpio_desc;
298 mutex_lock(&sysfs_lock);
300 if (!test_bit(FLAG_EXPORT, &desc->flags))
302 else if (!test_bit(FLAG_IS_OUT, &desc->flags))
307 status = strict_strtol(buf, 0, &value);
309 if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
311 gpio_set_value_cansleep(gpio, value != 0);
316 mutex_unlock(&sysfs_lock);
320 static const DEVICE_ATTR(value, 0644,
321 gpio_value_show, gpio_value_store);
323 static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
325 struct sysfs_dirent *value_sd = priv;
327 sysfs_notify_dirent(value_sd);
331 static int gpio_setup_irq(struct gpio_desc *desc, struct device *dev,
332 unsigned long gpio_flags)
334 struct sysfs_dirent *value_sd;
335 unsigned long irq_flags;
338 if ((desc->flags & GPIO_TRIGGER_MASK) == gpio_flags)
341 irq = gpio_to_irq(desc - gpio_desc);
345 id = desc->flags >> ID_SHIFT;
346 value_sd = idr_find(&dirent_idr, id);
348 free_irq(irq, value_sd);
350 desc->flags &= ~GPIO_TRIGGER_MASK;
357 irq_flags = IRQF_SHARED;
358 if (test_bit(FLAG_TRIG_FALL, &gpio_flags))
359 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
360 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
361 if (test_bit(FLAG_TRIG_RISE, &gpio_flags))
362 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
363 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
366 value_sd = sysfs_get_dirent(dev->kobj.sd, NULL, "value");
374 if (idr_pre_get(&dirent_idr, GFP_KERNEL))
375 ret = idr_get_new_above(&dirent_idr, value_sd,
377 } while (ret == -EAGAIN);
382 desc->flags &= GPIO_FLAGS_MASK;
383 desc->flags |= (unsigned long)id << ID_SHIFT;
385 if (desc->flags >> ID_SHIFT != id) {
391 ret = request_any_context_irq(irq, gpio_sysfs_irq, irq_flags,
392 "gpiolib", value_sd);
396 desc->flags |= gpio_flags;
400 idr_remove(&dirent_idr, id);
401 desc->flags &= GPIO_FLAGS_MASK;
409 static const struct {
412 } trigger_types[] = {
414 { "falling", BIT(FLAG_TRIG_FALL) },
415 { "rising", BIT(FLAG_TRIG_RISE) },
416 { "both", BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE) },
419 static ssize_t gpio_edge_show(struct device *dev,
420 struct device_attribute *attr, char *buf)
422 const struct gpio_desc *desc = dev_get_drvdata(dev);
425 mutex_lock(&sysfs_lock);
427 if (!test_bit(FLAG_EXPORT, &desc->flags))
433 for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
434 if ((desc->flags & GPIO_TRIGGER_MASK)
435 == trigger_types[i].flags) {
436 status = sprintf(buf, "%s\n",
437 trigger_types[i].name);
442 mutex_unlock(&sysfs_lock);
446 static ssize_t gpio_edge_store(struct device *dev,
447 struct device_attribute *attr, const char *buf, size_t size)
449 struct gpio_desc *desc = dev_get_drvdata(dev);
453 for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
454 if (sysfs_streq(trigger_types[i].name, buf))
459 mutex_lock(&sysfs_lock);
461 if (!test_bit(FLAG_EXPORT, &desc->flags))
464 status = gpio_setup_irq(desc, dev, trigger_types[i].flags);
469 mutex_unlock(&sysfs_lock);
474 static DEVICE_ATTR(edge, 0644, gpio_edge_show, gpio_edge_store);
476 static int sysfs_set_active_low(struct gpio_desc *desc, struct device *dev,
481 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
485 set_bit(FLAG_ACTIVE_LOW, &desc->flags);
487 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
489 /* reconfigure poll(2) support if enabled on one edge only */
490 if (dev != NULL && (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^
491 !!test_bit(FLAG_TRIG_FALL, &desc->flags))) {
492 unsigned long trigger_flags = desc->flags & GPIO_TRIGGER_MASK;
494 gpio_setup_irq(desc, dev, 0);
495 status = gpio_setup_irq(desc, dev, trigger_flags);
501 static ssize_t gpio_active_low_show(struct device *dev,
502 struct device_attribute *attr, char *buf)
504 const struct gpio_desc *desc = dev_get_drvdata(dev);
507 mutex_lock(&sysfs_lock);
509 if (!test_bit(FLAG_EXPORT, &desc->flags))
512 status = sprintf(buf, "%d\n",
513 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
515 mutex_unlock(&sysfs_lock);
520 static ssize_t gpio_active_low_store(struct device *dev,
521 struct device_attribute *attr, const char *buf, size_t size)
523 struct gpio_desc *desc = dev_get_drvdata(dev);
526 mutex_lock(&sysfs_lock);
528 if (!test_bit(FLAG_EXPORT, &desc->flags)) {
533 status = strict_strtol(buf, 0, &value);
535 status = sysfs_set_active_low(desc, dev, value != 0);
538 mutex_unlock(&sysfs_lock);
540 return status ? : size;
543 static const DEVICE_ATTR(active_low, 0644,
544 gpio_active_low_show, gpio_active_low_store);
546 static const struct attribute *gpio_attrs[] = {
547 &dev_attr_value.attr,
548 &dev_attr_active_low.attr,
552 static const struct attribute_group gpio_attr_group = {
553 .attrs = (struct attribute **) gpio_attrs,
557 * /sys/class/gpio/gpiochipN/
558 * /base ... matching gpio_chip.base (N)
559 * /label ... matching gpio_chip.label
560 * /ngpio ... matching gpio_chip.ngpio
563 static ssize_t chip_base_show(struct device *dev,
564 struct device_attribute *attr, char *buf)
566 const struct gpio_chip *chip = dev_get_drvdata(dev);
568 return sprintf(buf, "%d\n", chip->base);
570 static DEVICE_ATTR(base, 0444, chip_base_show, NULL);
572 static ssize_t chip_label_show(struct device *dev,
573 struct device_attribute *attr, char *buf)
575 const struct gpio_chip *chip = dev_get_drvdata(dev);
577 return sprintf(buf, "%s\n", chip->label ? : "");
579 static DEVICE_ATTR(label, 0444, chip_label_show, NULL);
581 static ssize_t chip_ngpio_show(struct device *dev,
582 struct device_attribute *attr, char *buf)
584 const struct gpio_chip *chip = dev_get_drvdata(dev);
586 return sprintf(buf, "%u\n", chip->ngpio);
588 static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL);
590 static struct attribute *gpiochip_attrs[] = {
592 &dev_attr_label.attr,
593 &dev_attr_ngpio.attr,
596 ATTRIBUTE_GROUPS(gpiochip);
599 * /sys/class/gpio/export ... write-only
600 * integer N ... number of GPIO to export (full access)
601 * /sys/class/gpio/unexport ... write-only
602 * integer N ... number of GPIO to unexport
604 static ssize_t export_store(struct class *class,
605 struct class_attribute *attr,
606 const char *buf, size_t len)
611 status = strict_strtol(buf, 0, &gpio);
615 /* No extra locking here; FLAG_SYSFS just signifies that the
616 * request and export were done by on behalf of userspace, so
617 * they may be undone on its behalf too.
620 status = gpio_request(gpio, "sysfs");
624 status = gpio_export(gpio, true);
628 set_bit(FLAG_SYSFS, &gpio_desc[gpio].flags);
632 pr_debug("%s: status %d\n", __func__, status);
633 return status ? : len;
636 static ssize_t unexport_store(struct class *class,
637 struct class_attribute *attr,
638 const char *buf, size_t len)
643 status = strict_strtol(buf, 0, &gpio);
649 /* reject bogus commands (gpio_unexport ignores them) */
650 if (!gpio_is_valid(gpio))
653 /* No extra locking here; FLAG_SYSFS just signifies that the
654 * request and export were done by on behalf of userspace, so
655 * they may be undone on its behalf too.
657 if (test_and_clear_bit(FLAG_SYSFS, &gpio_desc[gpio].flags)) {
663 pr_debug("%s: status %d\n", __func__, status);
664 return status ? : len;
667 static struct class_attribute gpio_class_attrs[] = {
668 __ATTR(export, 0200, NULL, export_store),
669 __ATTR(unexport, 0200, NULL, unexport_store),
673 static struct class gpio_class = {
675 .owner = THIS_MODULE,
677 .class_attrs = gpio_class_attrs,
682 * gpio_export - export a GPIO through sysfs
683 * @gpio: gpio to make available, already requested
684 * @direction_may_change: true if userspace may change gpio direction
685 * Context: arch_initcall or later
687 * When drivers want to make a GPIO accessible to userspace after they
688 * have requested it -- perhaps while debugging, or as part of their
689 * public interface -- they may use this routine. If the GPIO can
690 * change direction (some can't) and the caller allows it, userspace
691 * will see "direction" sysfs attribute which may be used to change
692 * the gpio's direction. A "value" attribute will always be provided.
694 * Returns zero on success, else an error.
696 int gpio_export(unsigned gpio, bool direction_may_change)
699 struct gpio_desc *desc;
700 int status = -EINVAL;
701 const char *ioname = NULL;
703 /* can't export until sysfs is available ... */
705 pr_debug("%s: called too early!\n", __func__);
709 if (!gpio_is_valid(gpio))
712 mutex_lock(&sysfs_lock);
714 spin_lock_irqsave(&gpio_lock, flags);
715 desc = &gpio_desc[gpio];
716 if (test_bit(FLAG_REQUESTED, &desc->flags)
717 && !test_bit(FLAG_EXPORT, &desc->flags)) {
719 if (!desc->chip->direction_input
720 || !desc->chip->direction_output)
721 direction_may_change = false;
723 spin_unlock_irqrestore(&gpio_lock, flags);
725 if (desc->chip->names && desc->chip->names[gpio - desc->chip->base])
726 ioname = desc->chip->names[gpio - desc->chip->base];
731 dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
732 desc, ioname ? ioname : "gpio%u", gpio);
734 status = sysfs_create_group(&dev->kobj,
737 if (!status && direction_may_change)
738 status = device_create_file(dev,
739 &dev_attr_direction);
741 if (!status && gpio_to_irq(gpio) >= 0
742 && (direction_may_change
743 || !test_bit(FLAG_IS_OUT,
745 status = device_create_file(dev,
749 device_unregister(dev);
751 status = PTR_ERR(dev);
753 set_bit(FLAG_EXPORT, &desc->flags);
756 mutex_unlock(&sysfs_lock);
760 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
764 EXPORT_SYMBOL_GPL(gpio_export);
766 static int match_export(struct device *dev, void *data)
768 return dev_get_drvdata(dev) == data;
772 * gpio_export_link - create a sysfs link to an exported GPIO node
773 * @dev: device under which to create symlink
774 * @name: name of the symlink
775 * @gpio: gpio to create symlink to, already exported
777 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
778 * node. Caller is responsible for unlinking.
780 * Returns zero on success, else an error.
782 int gpio_export_link(struct device *dev, const char *name, unsigned gpio)
784 struct gpio_desc *desc;
785 int status = -EINVAL;
787 if (!gpio_is_valid(gpio))
790 mutex_lock(&sysfs_lock);
792 desc = &gpio_desc[gpio];
794 if (test_bit(FLAG_EXPORT, &desc->flags)) {
797 tdev = class_find_device(&gpio_class, NULL, desc, match_export);
799 status = sysfs_create_link(&dev->kobj, &tdev->kobj,
806 mutex_unlock(&sysfs_lock);
810 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
814 EXPORT_SYMBOL_GPL(gpio_export_link);
818 * gpio_sysfs_set_active_low - set the polarity of gpio sysfs value
819 * @gpio: gpio to change
820 * @value: non-zero to use active low, i.e. inverted values
822 * Set the polarity of /sys/class/gpio/gpioN/value sysfs attribute.
823 * The GPIO does not have to be exported yet. If poll(2) support has
824 * been enabled for either rising or falling edge, it will be
825 * reconfigured to follow the new polarity.
827 * Returns zero on success, else an error.
829 int gpio_sysfs_set_active_low(unsigned gpio, int value)
831 struct gpio_desc *desc;
832 struct device *dev = NULL;
833 int status = -EINVAL;
835 if (!gpio_is_valid(gpio))
838 mutex_lock(&sysfs_lock);
840 desc = &gpio_desc[gpio];
842 if (test_bit(FLAG_EXPORT, &desc->flags)) {
843 dev = class_find_device(&gpio_class, NULL, desc, match_export);
850 status = sysfs_set_active_low(desc, dev, value);
853 mutex_unlock(&sysfs_lock);
857 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
861 EXPORT_SYMBOL_GPL(gpio_sysfs_set_active_low);
864 * gpio_unexport - reverse effect of gpio_export()
865 * @gpio: gpio to make unavailable
867 * This is implicit on gpio_free().
869 void gpio_unexport(unsigned gpio)
871 struct gpio_desc *desc;
874 if (!gpio_is_valid(gpio)) {
879 mutex_lock(&sysfs_lock);
881 desc = &gpio_desc[gpio];
883 if (test_bit(FLAG_EXPORT, &desc->flags)) {
884 struct device *dev = NULL;
886 dev = class_find_device(&gpio_class, NULL, desc, match_export);
888 gpio_setup_irq(desc, dev, 0);
889 clear_bit(FLAG_EXPORT, &desc->flags);
891 device_unregister(dev);
896 mutex_unlock(&sysfs_lock);
899 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
901 EXPORT_SYMBOL_GPL(gpio_unexport);
903 static int gpiochip_export(struct gpio_chip *chip)
908 /* Many systems register gpio chips for SOC support very early,
909 * before driver model support is available. In those cases we
910 * export this later, in gpiolib_sysfs_init() ... here we just
911 * verify that _some_ field of gpio_class got initialized.
916 /* use chip->base for the ID; it's already known to be unique */
917 mutex_lock(&sysfs_lock);
918 dev = device_create_with_groups(&gpio_class, chip->dev, MKDEV(0, 0),
919 chip, gpiochip_groups,
920 "gpiochip%d", chip->base);
922 status = PTR_ERR(dev);
925 chip->exported = (status == 0);
926 mutex_unlock(&sysfs_lock);
932 spin_lock_irqsave(&gpio_lock, flags);
934 while (gpio_desc[gpio].chip == chip)
935 gpio_desc[gpio++].chip = NULL;
936 spin_unlock_irqrestore(&gpio_lock, flags);
938 pr_debug("%s: chip %s status %d\n", __func__,
939 chip->label, status);
945 static void gpiochip_unexport(struct gpio_chip *chip)
950 mutex_lock(&sysfs_lock);
951 dev = class_find_device(&gpio_class, NULL, chip, match_export);
954 device_unregister(dev);
959 mutex_unlock(&sysfs_lock);
962 pr_debug("%s: chip %s status %d\n", __func__,
963 chip->label, status);
966 static int __init gpiolib_sysfs_init(void)
972 status = class_register(&gpio_class);
976 /* Scan and register the gpio_chips which registered very
977 * early (e.g. before the class_register above was called).
979 * We run before arch_initcall() so chip->dev nodes can have
980 * registered, and so arch_initcall() can always gpio_export().
982 spin_lock_irqsave(&gpio_lock, flags);
983 for (gpio = 0; gpio < ARCH_NR_GPIOS; gpio++) {
984 struct gpio_chip *chip;
986 chip = gpio_desc[gpio].chip;
987 if (!chip || chip->exported)
990 spin_unlock_irqrestore(&gpio_lock, flags);
991 status = gpiochip_export(chip);
992 spin_lock_irqsave(&gpio_lock, flags);
994 spin_unlock_irqrestore(&gpio_lock, flags);
999 postcore_initcall(gpiolib_sysfs_init);
1002 static inline int gpiochip_export(struct gpio_chip *chip)
1007 static inline void gpiochip_unexport(struct gpio_chip *chip)
1011 #endif /* CONFIG_GPIO_SYSFS */
1014 * gpiochip_add() - register a gpio_chip
1015 * @chip: the chip to register, with chip->base initialized
1016 * Context: potentially before irqs or kmalloc will work
1018 * Returns a negative errno if the chip can't be registered, such as
1019 * because the chip->base is invalid or already associated with a
1020 * different chip. Otherwise it returns zero as a success code.
1022 * When gpiochip_add() is called very early during boot, so that GPIOs
1023 * can be freely used, the chip->dev device must be registered before
1024 * the gpio framework's arch_initcall(). Otherwise sysfs initialization
1025 * for GPIOs will fail rudely.
1027 * If chip->base is negative, this requests dynamic assignment of
1028 * a range of valid GPIOs.
1030 int gpiochip_add(struct gpio_chip *chip)
1032 unsigned long flags;
1035 int base = chip->base;
1037 if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
1043 spin_lock_irqsave(&gpio_lock, flags);
1046 base = gpiochip_find_base(chip->ngpio);
1054 /* these GPIO numbers must not be managed by another gpio_chip */
1055 for (id = base; id < base + chip->ngpio; id++) {
1056 if (gpio_desc[id].chip != NULL) {
1062 for (id = base; id < base + chip->ngpio; id++) {
1063 gpio_desc[id].chip = chip;
1065 /* REVISIT: most hardware initializes GPIOs as
1066 * inputs (often with pullups enabled) so power
1067 * usage is minimized. Linux code should set the
1068 * gpio direction first thing; but until it does,
1069 * we may expose the wrong direction in sysfs.
1071 gpio_desc[id].flags = !chip->direction_input
1072 ? (1 << FLAG_IS_OUT)
1076 of_gpiochip_add(chip);
1080 spin_unlock_irqrestore(&gpio_lock, flags);
1085 status = gpiochip_export(chip);
1087 of_gpiochip_remove(chip);
1093 /* failures here can mean systems won't boot... */
1094 pr_err("gpiochip_add: gpios %d..%d (%s) failed to register\n",
1095 chip->base, chip->base + chip->ngpio - 1,
1096 chip->label ? : "generic");
1099 EXPORT_SYMBOL_GPL(gpiochip_add);
1102 * gpiochip_remove() - unregister a gpio_chip
1103 * @chip: the chip to unregister
1105 * A gpio_chip with any GPIOs still requested may not be removed.
1107 int gpiochip_remove(struct gpio_chip *chip)
1109 unsigned long flags;
1113 spin_lock_irqsave(&gpio_lock, flags);
1115 of_gpiochip_remove(chip);
1117 for (id = chip->base; id < chip->base + chip->ngpio; id++) {
1118 if (test_bit(FLAG_REQUESTED, &gpio_desc[id].flags)) {
1124 for (id = chip->base; id < chip->base + chip->ngpio; id++)
1125 gpio_desc[id].chip = NULL;
1128 spin_unlock_irqrestore(&gpio_lock, flags);
1131 gpiochip_unexport(chip);
1135 EXPORT_SYMBOL_GPL(gpiochip_remove);
1138 * gpiochip_find() - iterator for locating a specific gpio_chip
1139 * @data: data to pass to match function
1140 * @callback: Callback function to check gpio_chip
1142 * Similar to bus_find_device. It returns a reference to a gpio_chip as
1143 * determined by a user supplied @match callback. The callback should return
1144 * 0 if the device doesn't match and non-zero if it does. If the callback is
1145 * non-zero, this function will return to the caller and not iterate over any
1148 struct gpio_chip *gpiochip_find(void *data,
1149 int (*match)(struct gpio_chip *chip, void *data))
1151 struct gpio_chip *chip = NULL;
1152 unsigned long flags;
1155 spin_lock_irqsave(&gpio_lock, flags);
1156 for (i = 0; i < ARCH_NR_GPIOS; i++) {
1157 if (!gpio_desc[i].chip)
1160 if (match(gpio_desc[i].chip, data)) {
1161 chip = gpio_desc[i].chip;
1165 spin_unlock_irqrestore(&gpio_lock, flags);
1169 EXPORT_SYMBOL_GPL(gpiochip_find);
1171 /* These "optional" allocation calls help prevent drivers from stomping
1172 * on each other, and help provide better diagnostics in debugfs.
1173 * They're called even less than the "set direction" calls.
1175 int gpio_request(unsigned gpio, const char *label)
1177 struct gpio_desc *desc;
1178 struct gpio_chip *chip;
1179 int status = -EINVAL;
1180 unsigned long flags;
1182 spin_lock_irqsave(&gpio_lock, flags);
1184 if (!gpio_is_valid(gpio))
1186 desc = &gpio_desc[gpio];
1191 if (!try_module_get(chip->owner))
1194 /* NOTE: gpio_request() can be called in early boot,
1195 * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
1198 if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
1199 desc_set_label(desc, label ? : "?");
1203 module_put(chip->owner);
1207 if (chip->request) {
1208 /* chip->request may sleep */
1209 spin_unlock_irqrestore(&gpio_lock, flags);
1210 status = chip->request(chip, gpio - chip->base);
1211 spin_lock_irqsave(&gpio_lock, flags);
1214 desc_set_label(desc, NULL);
1215 module_put(chip->owner);
1216 clear_bit(FLAG_REQUESTED, &desc->flags);
1222 pr_debug("gpio_request: gpio-%d (%s) status %d\n",
1223 gpio, label ? : "?", status);
1224 spin_unlock_irqrestore(&gpio_lock, flags);
1227 EXPORT_SYMBOL_GPL(gpio_request);
1229 void gpio_free(unsigned gpio)
1231 unsigned long flags;
1232 struct gpio_desc *desc;
1233 struct gpio_chip *chip;
1237 if (!gpio_is_valid(gpio)) {
1238 WARN_ON(extra_checks);
1242 gpio_unexport(gpio);
1244 spin_lock_irqsave(&gpio_lock, flags);
1246 desc = &gpio_desc[gpio];
1248 if (chip && test_bit(FLAG_REQUESTED, &desc->flags)) {
1250 spin_unlock_irqrestore(&gpio_lock, flags);
1251 might_sleep_if(chip->can_sleep);
1252 chip->free(chip, gpio - chip->base);
1253 spin_lock_irqsave(&gpio_lock, flags);
1255 desc_set_label(desc, NULL);
1256 module_put(desc->chip->owner);
1257 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
1258 clear_bit(FLAG_REQUESTED, &desc->flags);
1260 WARN_ON(extra_checks);
1262 spin_unlock_irqrestore(&gpio_lock, flags);
1264 EXPORT_SYMBOL_GPL(gpio_free);
1267 * gpio_request_one - request a single GPIO with initial configuration
1268 * @gpio: the GPIO number
1269 * @flags: GPIO configuration as specified by GPIOF_*
1270 * @label: a literal description string of this GPIO
1272 int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
1276 err = gpio_request(gpio, label);
1280 if (flags & GPIOF_DIR_IN)
1281 err = gpio_direction_input(gpio);
1283 err = gpio_direction_output(gpio,
1284 (flags & GPIOF_INIT_HIGH) ? 1 : 0);
1291 EXPORT_SYMBOL_GPL(gpio_request_one);
1294 * gpio_request_array - request multiple GPIOs in a single call
1295 * @array: array of the 'struct gpio'
1296 * @num: how many GPIOs in the array
1298 int gpio_request_array(const struct gpio *array, size_t num)
1302 for (i = 0; i < num; i++, array++) {
1303 err = gpio_request_one(array->gpio, array->flags, array->label);
1311 gpio_free((--array)->gpio);
1314 EXPORT_SYMBOL_GPL(gpio_request_array);
1317 * gpio_free_array - release multiple GPIOs in a single call
1318 * @array: array of the 'struct gpio'
1319 * @num: how many GPIOs in the array
1321 void gpio_free_array(const struct gpio *array, size_t num)
1324 gpio_free((array++)->gpio);
1326 EXPORT_SYMBOL_GPL(gpio_free_array);
1329 * gpiochip_is_requested - return string iff signal was requested
1330 * @chip: controller managing the signal
1331 * @offset: of signal within controller's 0..(ngpio - 1) range
1333 * Returns NULL if the GPIO is not currently requested, else a string.
1334 * If debugfs support is enabled, the string returned is the label passed
1335 * to gpio_request(); otherwise it is a meaningless constant.
1337 * This function is for use by GPIO controller drivers. The label can
1338 * help with diagnostics, and knowing that the signal is used as a GPIO
1339 * can help avoid accidentally multiplexing it to another controller.
1341 const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
1343 unsigned gpio = chip->base + offset;
1345 if (!gpio_is_valid(gpio) || gpio_desc[gpio].chip != chip)
1347 if (test_bit(FLAG_REQUESTED, &gpio_desc[gpio].flags) == 0)
1349 #ifdef CONFIG_DEBUG_FS
1350 return gpio_desc[gpio].label;
1355 EXPORT_SYMBOL_GPL(gpiochip_is_requested);
1358 /* Drivers MUST set GPIO direction before making get/set calls. In
1359 * some cases this is done in early boot, before IRQs are enabled.
1361 * As a rule these aren't called more than once (except for drivers
1362 * using the open-drain emulation idiom) so these are natural places
1363 * to accumulate extra debugging checks. Note that we can't (yet)
1364 * rely on gpio_request() having been called beforehand.
1367 int gpio_direction_input(unsigned gpio)
1369 unsigned long flags;
1370 struct gpio_chip *chip;
1371 struct gpio_desc *desc = &gpio_desc[gpio];
1372 int status = -EINVAL;
1374 spin_lock_irqsave(&gpio_lock, flags);
1376 if (!gpio_is_valid(gpio))
1379 if (!chip || !chip->get || !chip->direction_input)
1382 if (gpio >= chip->ngpio)
1384 status = gpio_ensure_requested(desc, gpio);
1388 /* now we know the gpio is valid and chip won't vanish */
1390 spin_unlock_irqrestore(&gpio_lock, flags);
1392 might_sleep_if(chip->can_sleep);
1395 status = chip->request(chip, gpio);
1397 pr_debug("GPIO-%d: chip request fail, %d\n",
1398 chip->base + gpio, status);
1399 /* and it's not available to anyone else ...
1400 * gpio_request() is the fully clean solution.
1406 status = chip->direction_input(chip, gpio);
1408 clear_bit(FLAG_IS_OUT, &desc->flags);
1410 trace_gpio_direction(chip->base + gpio, 1, status);
1414 spin_unlock_irqrestore(&gpio_lock, flags);
1416 pr_debug("%s: gpio-%d status %d\n",
1417 __func__, gpio, status);
1420 EXPORT_SYMBOL_GPL(gpio_direction_input);
1422 int gpio_direction_output(unsigned gpio, int value)
1424 unsigned long flags;
1425 struct gpio_chip *chip;
1426 struct gpio_desc *desc = &gpio_desc[gpio];
1427 int status = -EINVAL;
1429 spin_lock_irqsave(&gpio_lock, flags);
1431 if (!gpio_is_valid(gpio))
1434 if (!chip || !chip->set || !chip->direction_output)
1437 if (gpio >= chip->ngpio)
1439 status = gpio_ensure_requested(desc, gpio);
1443 /* now we know the gpio is valid and chip won't vanish */
1445 spin_unlock_irqrestore(&gpio_lock, flags);
1447 might_sleep_if(chip->can_sleep);
1450 status = chip->request(chip, gpio);
1452 pr_debug("GPIO-%d: chip request fail, %d\n",
1453 chip->base + gpio, status);
1454 /* and it's not available to anyone else ...
1455 * gpio_request() is the fully clean solution.
1461 status = chip->direction_output(chip, gpio, value);
1463 set_bit(FLAG_IS_OUT, &desc->flags);
1464 trace_gpio_value(chip->base + gpio, 0, value);
1465 trace_gpio_direction(chip->base + gpio, 0, status);
1469 spin_unlock_irqrestore(&gpio_lock, flags);
1471 pr_debug("%s: gpio-%d status %d\n",
1472 __func__, gpio, status);
1475 EXPORT_SYMBOL_GPL(gpio_direction_output);
1478 * gpio_set_debounce - sets @debounce time for a @gpio
1479 * @gpio: the gpio to set debounce time
1480 * @debounce: debounce time is microseconds
1482 int gpio_set_debounce(unsigned gpio, unsigned debounce)
1484 unsigned long flags;
1485 struct gpio_chip *chip;
1486 struct gpio_desc *desc = &gpio_desc[gpio];
1487 int status = -EINVAL;
1489 spin_lock_irqsave(&gpio_lock, flags);
1491 if (!gpio_is_valid(gpio))
1494 if (!chip || !chip->set || !chip->set_debounce)
1497 if (gpio >= chip->ngpio)
1499 status = gpio_ensure_requested(desc, gpio);
1503 /* now we know the gpio is valid and chip won't vanish */
1505 spin_unlock_irqrestore(&gpio_lock, flags);
1507 might_sleep_if(chip->can_sleep);
1509 return chip->set_debounce(chip, gpio, debounce);
1512 spin_unlock_irqrestore(&gpio_lock, flags);
1514 pr_debug("%s: gpio-%d status %d\n",
1515 __func__, gpio, status);
1519 EXPORT_SYMBOL_GPL(gpio_set_debounce);
1521 /* I/O calls are only valid after configuration completed; the relevant
1522 * "is this a valid GPIO" error checks should already have been done.
1524 * "Get" operations are often inlinable as reading a pin value register,
1525 * and masking the relevant bit in that register.
1527 * When "set" operations are inlinable, they involve writing that mask to
1528 * one register to set a low value, or a different register to set it high.
1529 * Otherwise locking is needed, so there may be little value to inlining.
1531 *------------------------------------------------------------------------
1533 * IMPORTANT!!! The hot paths -- get/set value -- assume that callers
1534 * have requested the GPIO. That can include implicit requesting by
1535 * a direction setting call. Marking a gpio as requested locks its chip
1536 * in memory, guaranteeing that these table lookups need no more locking
1537 * and that gpiochip_remove() will fail.
1539 * REVISIT when debugging, consider adding some instrumentation to ensure
1540 * that the GPIO was actually requested.
1544 * __gpio_get_value() - return a gpio's value
1545 * @gpio: gpio whose value will be returned
1548 * This is used directly or indirectly to implement gpio_get_value().
1549 * It returns the zero or nonzero value provided by the associated
1550 * gpio_chip.get() method; or zero if no such method is provided.
1552 int __gpio_get_value(unsigned gpio)
1554 struct gpio_chip *chip;
1557 chip = gpio_to_chip(gpio);
1558 WARN_ON(chip->can_sleep);
1559 value = chip->get ? chip->get(chip, gpio - chip->base) : 0;
1560 trace_gpio_value(gpio, 1, value);
1563 EXPORT_SYMBOL_GPL(__gpio_get_value);
1566 * __gpio_set_value() - assign a gpio's value
1567 * @gpio: gpio whose value will be assigned
1568 * @value: value to assign
1571 * This is used directly or indirectly to implement gpio_set_value().
1572 * It invokes the associated gpio_chip.set() method.
1574 void __gpio_set_value(unsigned gpio, int value)
1576 struct gpio_chip *chip;
1578 chip = gpio_to_chip(gpio);
1579 WARN_ON(chip->can_sleep);
1580 trace_gpio_value(gpio, 0, value);
1581 chip->set(chip, gpio - chip->base, value);
1583 EXPORT_SYMBOL_GPL(__gpio_set_value);
1586 * __gpio_cansleep() - report whether gpio value access will sleep
1587 * @gpio: gpio in question
1590 * This is used directly or indirectly to implement gpio_cansleep(). It
1591 * returns nonzero if access reading or writing the GPIO value can sleep.
1593 int __gpio_cansleep(unsigned gpio)
1595 struct gpio_chip *chip;
1597 /* only call this on GPIOs that are valid! */
1598 chip = gpio_to_chip(gpio);
1600 return chip->can_sleep;
1602 EXPORT_SYMBOL_GPL(__gpio_cansleep);
1605 * __gpio_to_irq() - return the IRQ corresponding to a GPIO
1606 * @gpio: gpio whose IRQ will be returned (already requested)
1609 * This is used directly or indirectly to implement gpio_to_irq().
1610 * It returns the number of the IRQ signaled by this (input) GPIO,
1611 * or a negative errno.
1613 int __gpio_to_irq(unsigned gpio)
1615 struct gpio_chip *chip;
1617 chip = gpio_to_chip(gpio);
1618 return chip->to_irq ? chip->to_irq(chip, gpio - chip->base) : -ENXIO;
1620 EXPORT_SYMBOL_GPL(__gpio_to_irq);
1624 /* There's no value in making it easy to inline GPIO calls that may sleep.
1625 * Common examples include ones connected to I2C or SPI chips.
1628 int gpio_get_value_cansleep(unsigned gpio)
1630 struct gpio_chip *chip;
1633 might_sleep_if(extra_checks);
1634 chip = gpio_to_chip(gpio);
1635 value = chip->get ? chip->get(chip, gpio - chip->base) : 0;
1636 trace_gpio_value(gpio, 1, value);
1639 EXPORT_SYMBOL_GPL(gpio_get_value_cansleep);
1641 void gpio_set_value_cansleep(unsigned gpio, int value)
1643 struct gpio_chip *chip;
1645 might_sleep_if(extra_checks);
1646 chip = gpio_to_chip(gpio);
1647 trace_gpio_value(gpio, 0, value);
1648 chip->set(chip, gpio - chip->base, value);
1650 EXPORT_SYMBOL_GPL(gpio_set_value_cansleep);
1653 #ifdef CONFIG_DEBUG_FS
1655 static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
1658 unsigned gpio = chip->base;
1659 struct gpio_desc *gdesc = &gpio_desc[gpio];
1662 for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) {
1663 if (!test_bit(FLAG_REQUESTED, &gdesc->flags))
1666 is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
1667 seq_printf(s, " gpio-%-3d (%-20.20s) %s %s",
1669 is_out ? "out" : "in ",
1671 ? (chip->get(chip, i) ? "hi" : "lo")
1673 seq_printf(s, "\n");
1677 static int gpiolib_show(struct seq_file *s, void *unused)
1679 struct gpio_chip *chip = NULL;
1683 /* REVISIT this isn't locked against gpio_chip removal ... */
1685 for (gpio = 0; gpio_is_valid(gpio); gpio++) {
1688 if (chip == gpio_desc[gpio].chip)
1690 chip = gpio_desc[gpio].chip;
1694 seq_printf(s, "%sGPIOs %d-%d",
1695 started ? "\n" : "",
1696 chip->base, chip->base + chip->ngpio - 1);
1699 seq_printf(s, ", %s/%s",
1700 dev->bus ? dev->bus->name : "no-bus",
1703 seq_printf(s, ", %s", chip->label);
1704 if (chip->can_sleep)
1705 seq_printf(s, ", can sleep");
1706 seq_printf(s, ":\n");
1710 chip->dbg_show(s, chip);
1712 gpiolib_dbg_show(s, chip);
1717 static int gpiolib_open(struct inode *inode, struct file *file)
1719 return single_open(file, gpiolib_show, NULL);
1722 static const struct file_operations gpiolib_operations = {
1723 .open = gpiolib_open,
1725 .llseek = seq_lseek,
1726 .release = single_release,
1729 static int __init gpiolib_debugfs_init(void)
1731 /* /sys/kernel/debug/gpio */
1732 (void) debugfs_create_file("gpio", S_IFREG | S_IRUGO,
1733 NULL, NULL, &gpiolib_operations);
1736 subsys_initcall(gpiolib_debugfs_init);
1738 #endif /* DEBUG_FS */