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 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 DEVICE_ATTR(active_low, 0644,
544 gpio_active_low_show, gpio_active_low_store);
546 static struct attribute *gpio_attrs[] = {
547 &dev_attr_value.attr,
548 &dev_attr_active_low.attr,
551 ATTRIBUTE_GROUPS(gpio);
554 * /sys/class/gpio/gpiochipN/
555 * /base ... matching gpio_chip.base (N)
556 * /label ... matching gpio_chip.label
557 * /ngpio ... matching gpio_chip.ngpio
560 static ssize_t chip_base_show(struct device *dev,
561 struct device_attribute *attr, char *buf)
563 const struct gpio_chip *chip = dev_get_drvdata(dev);
565 return sprintf(buf, "%d\n", chip->base);
567 static DEVICE_ATTR(base, 0444, chip_base_show, NULL);
569 static ssize_t chip_label_show(struct device *dev,
570 struct device_attribute *attr, char *buf)
572 const struct gpio_chip *chip = dev_get_drvdata(dev);
574 return sprintf(buf, "%s\n", chip->label ? : "");
576 static DEVICE_ATTR(label, 0444, chip_label_show, NULL);
578 static ssize_t chip_ngpio_show(struct device *dev,
579 struct device_attribute *attr, char *buf)
581 const struct gpio_chip *chip = dev_get_drvdata(dev);
583 return sprintf(buf, "%u\n", chip->ngpio);
585 static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL);
587 static struct attribute *gpiochip_attrs[] = {
589 &dev_attr_label.attr,
590 &dev_attr_ngpio.attr,
593 ATTRIBUTE_GROUPS(gpiochip);
596 * /sys/class/gpio/export ... write-only
597 * integer N ... number of GPIO to export (full access)
598 * /sys/class/gpio/unexport ... write-only
599 * integer N ... number of GPIO to unexport
601 static ssize_t export_store(struct class *class,
602 struct class_attribute *attr,
603 const char *buf, size_t len)
608 status = strict_strtol(buf, 0, &gpio);
612 /* No extra locking here; FLAG_SYSFS just signifies that the
613 * request and export were done by on behalf of userspace, so
614 * they may be undone on its behalf too.
617 status = gpio_request(gpio, "sysfs");
621 status = gpio_export(gpio, true);
625 set_bit(FLAG_SYSFS, &gpio_desc[gpio].flags);
629 pr_debug("%s: status %d\n", __func__, status);
630 return status ? : len;
633 static ssize_t unexport_store(struct class *class,
634 struct class_attribute *attr,
635 const char *buf, size_t len)
640 status = strict_strtol(buf, 0, &gpio);
646 /* reject bogus commands (gpio_unexport ignores them) */
647 if (!gpio_is_valid(gpio))
650 /* No extra locking here; FLAG_SYSFS just signifies that the
651 * request and export were done by on behalf of userspace, so
652 * they may be undone on its behalf too.
654 if (test_and_clear_bit(FLAG_SYSFS, &gpio_desc[gpio].flags)) {
660 pr_debug("%s: status %d\n", __func__, status);
661 return status ? : len;
664 static struct class_attribute gpio_class_attrs[] = {
665 __ATTR(export, 0200, NULL, export_store),
666 __ATTR(unexport, 0200, NULL, unexport_store),
670 static struct class gpio_class = {
672 .owner = THIS_MODULE,
674 .class_attrs = gpio_class_attrs,
679 * gpio_export - export a GPIO through sysfs
680 * @gpio: gpio to make available, already requested
681 * @direction_may_change: true if userspace may change gpio direction
682 * Context: arch_initcall or later
684 * When drivers want to make a GPIO accessible to userspace after they
685 * have requested it -- perhaps while debugging, or as part of their
686 * public interface -- they may use this routine. If the GPIO can
687 * change direction (some can't) and the caller allows it, userspace
688 * will see "direction" sysfs attribute which may be used to change
689 * the gpio's direction. A "value" attribute will always be provided.
691 * Returns zero on success, else an error.
693 int gpio_export(unsigned gpio, bool direction_may_change)
696 struct gpio_desc *desc;
698 const char *ioname = NULL;
701 /* can't export until sysfs is available ... */
703 pr_debug("%s: called too early!\n", __func__);
707 if (!gpio_is_valid(gpio)) {
708 pr_debug("%s: gpio %d is not valid\n", __func__, 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)) {
718 spin_unlock_irqrestore(&gpio_lock, flags);
719 pr_debug("%s: gpio %d unavailable (requested=%d, exported=%d)\n",
721 test_bit(FLAG_REQUESTED, &desc->flags),
722 test_bit(FLAG_EXPORT, &desc->flags));
726 if (!desc->chip->direction_input || !desc->chip->direction_output)
727 direction_may_change = false;
728 spin_unlock_irqrestore(&gpio_lock, flags);
730 if (desc->chip->names && desc->chip->names[gpio - desc->chip->base])
731 ioname = desc->chip->names[gpio - desc->chip->base];
733 dev = device_create_with_groups(&gpio_class, desc->chip->dev,
734 MKDEV(0, 0), desc, gpio_groups,
735 ioname ? ioname : "gpio%u", gpio);
737 status = PTR_ERR(dev);
741 if (direction_may_change) {
742 status = device_create_file(dev, &dev_attr_direction);
744 goto fail_unregister_device;
747 if (gpio_to_irq(gpio) >= 0 && (direction_may_change ||
748 !test_bit(FLAG_IS_OUT, &desc->flags))) {
749 status = device_create_file(dev, &dev_attr_edge);
751 goto fail_remove_attr_direction;
754 set_bit(FLAG_EXPORT, &desc->flags);
755 mutex_unlock(&sysfs_lock);
758 fail_remove_attr_direction:
759 device_remove_file(dev, &dev_attr_direction);
760 fail_unregister_device:
761 device_unregister(dev);
763 mutex_unlock(&sysfs_lock);
764 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
767 EXPORT_SYMBOL_GPL(gpio_export);
769 static int match_export(struct device *dev, void *data)
771 return dev_get_drvdata(dev) == data;
775 * gpio_export_link - create a sysfs link to an exported GPIO node
776 * @dev: device under which to create symlink
777 * @name: name of the symlink
778 * @gpio: gpio to create symlink to, already exported
780 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
781 * node. Caller is responsible for unlinking.
783 * Returns zero on success, else an error.
785 int gpio_export_link(struct device *dev, const char *name, unsigned gpio)
787 struct gpio_desc *desc;
788 int status = -EINVAL;
790 if (!gpio_is_valid(gpio))
793 mutex_lock(&sysfs_lock);
795 desc = &gpio_desc[gpio];
797 if (test_bit(FLAG_EXPORT, &desc->flags)) {
800 tdev = class_find_device(&gpio_class, NULL, desc, match_export);
802 status = sysfs_create_link(&dev->kobj, &tdev->kobj,
809 mutex_unlock(&sysfs_lock);
813 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
817 EXPORT_SYMBOL_GPL(gpio_export_link);
821 * gpio_sysfs_set_active_low - set the polarity of gpio sysfs value
822 * @gpio: gpio to change
823 * @value: non-zero to use active low, i.e. inverted values
825 * Set the polarity of /sys/class/gpio/gpioN/value sysfs attribute.
826 * The GPIO does not have to be exported yet. If poll(2) support has
827 * been enabled for either rising or falling edge, it will be
828 * reconfigured to follow the new polarity.
830 * Returns zero on success, else an error.
832 int gpio_sysfs_set_active_low(unsigned gpio, int value)
834 struct gpio_desc *desc;
835 struct device *dev = NULL;
836 int status = -EINVAL;
838 if (!gpio_is_valid(gpio))
841 mutex_lock(&sysfs_lock);
843 desc = &gpio_desc[gpio];
845 if (test_bit(FLAG_EXPORT, &desc->flags)) {
846 dev = class_find_device(&gpio_class, NULL, desc, match_export);
853 status = sysfs_set_active_low(desc, dev, value);
856 mutex_unlock(&sysfs_lock);
860 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
864 EXPORT_SYMBOL_GPL(gpio_sysfs_set_active_low);
867 * gpio_unexport - reverse effect of gpio_export()
868 * @gpio: gpio to make unavailable
870 * This is implicit on gpio_free().
872 void gpio_unexport(unsigned gpio)
874 struct gpio_desc *desc;
876 struct device *dev = NULL;
878 if (!gpio_is_valid(gpio)) {
883 mutex_lock(&sysfs_lock);
885 desc = &gpio_desc[gpio];
887 if (test_bit(FLAG_EXPORT, &desc->flags)) {
889 dev = class_find_device(&gpio_class, NULL, desc, match_export);
891 gpio_setup_irq(desc, dev, 0);
892 clear_bit(FLAG_EXPORT, &desc->flags);
897 mutex_unlock(&sysfs_lock);
899 device_remove_file(dev, &dev_attr_edge);
900 device_remove_file(dev, &dev_attr_direction);
901 device_unregister(dev);
906 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
908 EXPORT_SYMBOL_GPL(gpio_unexport);
910 static int gpiochip_export(struct gpio_chip *chip)
915 /* Many systems register gpio chips for SOC support very early,
916 * before driver model support is available. In those cases we
917 * export this later, in gpiolib_sysfs_init() ... here we just
918 * verify that _some_ field of gpio_class got initialized.
923 /* use chip->base for the ID; it's already known to be unique */
924 mutex_lock(&sysfs_lock);
925 dev = device_create_with_groups(&gpio_class, chip->dev, MKDEV(0, 0),
926 chip, gpiochip_groups,
927 "gpiochip%d", chip->base);
929 status = PTR_ERR(dev);
932 chip->exported = (status == 0);
933 mutex_unlock(&sysfs_lock);
939 spin_lock_irqsave(&gpio_lock, flags);
941 while (gpio_desc[gpio].chip == chip)
942 gpio_desc[gpio++].chip = NULL;
943 spin_unlock_irqrestore(&gpio_lock, flags);
945 pr_debug("%s: chip %s status %d\n", __func__,
946 chip->label, status);
952 static void gpiochip_unexport(struct gpio_chip *chip)
957 mutex_lock(&sysfs_lock);
958 dev = class_find_device(&gpio_class, NULL, chip, match_export);
961 device_unregister(dev);
966 mutex_unlock(&sysfs_lock);
969 pr_debug("%s: chip %s status %d\n", __func__,
970 chip->label, status);
973 static int __init gpiolib_sysfs_init(void)
979 status = class_register(&gpio_class);
983 /* Scan and register the gpio_chips which registered very
984 * early (e.g. before the class_register above was called).
986 * We run before arch_initcall() so chip->dev nodes can have
987 * registered, and so arch_initcall() can always gpio_export().
989 spin_lock_irqsave(&gpio_lock, flags);
990 for (gpio = 0; gpio < ARCH_NR_GPIOS; gpio++) {
991 struct gpio_chip *chip;
993 chip = gpio_desc[gpio].chip;
994 if (!chip || chip->exported)
997 spin_unlock_irqrestore(&gpio_lock, flags);
998 status = gpiochip_export(chip);
999 spin_lock_irqsave(&gpio_lock, flags);
1001 spin_unlock_irqrestore(&gpio_lock, flags);
1006 postcore_initcall(gpiolib_sysfs_init);
1009 static inline int gpiochip_export(struct gpio_chip *chip)
1014 static inline void gpiochip_unexport(struct gpio_chip *chip)
1018 #endif /* CONFIG_GPIO_SYSFS */
1021 * gpiochip_add() - register a gpio_chip
1022 * @chip: the chip to register, with chip->base initialized
1023 * Context: potentially before irqs or kmalloc will work
1025 * Returns a negative errno if the chip can't be registered, such as
1026 * because the chip->base is invalid or already associated with a
1027 * different chip. Otherwise it returns zero as a success code.
1029 * When gpiochip_add() is called very early during boot, so that GPIOs
1030 * can be freely used, the chip->dev device must be registered before
1031 * the gpio framework's arch_initcall(). Otherwise sysfs initialization
1032 * for GPIOs will fail rudely.
1034 * If chip->base is negative, this requests dynamic assignment of
1035 * a range of valid GPIOs.
1037 int gpiochip_add(struct gpio_chip *chip)
1039 unsigned long flags;
1042 int base = chip->base;
1044 if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
1050 spin_lock_irqsave(&gpio_lock, flags);
1053 base = gpiochip_find_base(chip->ngpio);
1061 /* these GPIO numbers must not be managed by another gpio_chip */
1062 for (id = base; id < base + chip->ngpio; id++) {
1063 if (gpio_desc[id].chip != NULL) {
1069 for (id = base; id < base + chip->ngpio; id++) {
1070 gpio_desc[id].chip = chip;
1072 /* REVISIT: most hardware initializes GPIOs as
1073 * inputs (often with pullups enabled) so power
1074 * usage is minimized. Linux code should set the
1075 * gpio direction first thing; but until it does,
1076 * we may expose the wrong direction in sysfs.
1078 gpio_desc[id].flags = !chip->direction_input
1079 ? (1 << FLAG_IS_OUT)
1083 of_gpiochip_add(chip);
1087 spin_unlock_irqrestore(&gpio_lock, flags);
1092 status = gpiochip_export(chip);
1094 of_gpiochip_remove(chip);
1100 /* failures here can mean systems won't boot... */
1101 pr_err("gpiochip_add: gpios %d..%d (%s) failed to register\n",
1102 chip->base, chip->base + chip->ngpio - 1,
1103 chip->label ? : "generic");
1106 EXPORT_SYMBOL_GPL(gpiochip_add);
1109 * gpiochip_remove() - unregister a gpio_chip
1110 * @chip: the chip to unregister
1112 * A gpio_chip with any GPIOs still requested may not be removed.
1114 int gpiochip_remove(struct gpio_chip *chip)
1116 unsigned long flags;
1120 spin_lock_irqsave(&gpio_lock, flags);
1122 of_gpiochip_remove(chip);
1124 for (id = chip->base; id < chip->base + chip->ngpio; id++) {
1125 if (test_bit(FLAG_REQUESTED, &gpio_desc[id].flags)) {
1131 for (id = chip->base; id < chip->base + chip->ngpio; id++)
1132 gpio_desc[id].chip = NULL;
1135 spin_unlock_irqrestore(&gpio_lock, flags);
1138 gpiochip_unexport(chip);
1142 EXPORT_SYMBOL_GPL(gpiochip_remove);
1145 * gpiochip_find() - iterator for locating a specific gpio_chip
1146 * @data: data to pass to match function
1147 * @callback: Callback function to check gpio_chip
1149 * Similar to bus_find_device. It returns a reference to a gpio_chip as
1150 * determined by a user supplied @match callback. The callback should return
1151 * 0 if the device doesn't match and non-zero if it does. If the callback is
1152 * non-zero, this function will return to the caller and not iterate over any
1155 struct gpio_chip *gpiochip_find(void *data,
1156 int (*match)(struct gpio_chip *chip, void *data))
1158 struct gpio_chip *chip = NULL;
1159 unsigned long flags;
1162 spin_lock_irqsave(&gpio_lock, flags);
1163 for (i = 0; i < ARCH_NR_GPIOS; i++) {
1164 if (!gpio_desc[i].chip)
1167 if (match(gpio_desc[i].chip, data)) {
1168 chip = gpio_desc[i].chip;
1172 spin_unlock_irqrestore(&gpio_lock, flags);
1176 EXPORT_SYMBOL_GPL(gpiochip_find);
1178 /* These "optional" allocation calls help prevent drivers from stomping
1179 * on each other, and help provide better diagnostics in debugfs.
1180 * They're called even less than the "set direction" calls.
1182 int gpio_request(unsigned gpio, const char *label)
1184 struct gpio_desc *desc;
1185 struct gpio_chip *chip;
1186 int status = -EINVAL;
1187 unsigned long flags;
1189 spin_lock_irqsave(&gpio_lock, flags);
1191 if (!gpio_is_valid(gpio))
1193 desc = &gpio_desc[gpio];
1198 if (!try_module_get(chip->owner))
1201 /* NOTE: gpio_request() can be called in early boot,
1202 * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
1205 if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
1206 desc_set_label(desc, label ? : "?");
1210 module_put(chip->owner);
1214 if (chip->request) {
1215 /* chip->request may sleep */
1216 spin_unlock_irqrestore(&gpio_lock, flags);
1217 status = chip->request(chip, gpio - chip->base);
1218 spin_lock_irqsave(&gpio_lock, flags);
1221 desc_set_label(desc, NULL);
1222 module_put(chip->owner);
1223 clear_bit(FLAG_REQUESTED, &desc->flags);
1229 pr_debug("gpio_request: gpio-%d (%s) status %d\n",
1230 gpio, label ? : "?", status);
1231 spin_unlock_irqrestore(&gpio_lock, flags);
1234 EXPORT_SYMBOL_GPL(gpio_request);
1236 void gpio_free(unsigned gpio)
1238 unsigned long flags;
1239 struct gpio_desc *desc;
1240 struct gpio_chip *chip;
1244 if (!gpio_is_valid(gpio)) {
1245 WARN_ON(extra_checks);
1249 gpio_unexport(gpio);
1251 spin_lock_irqsave(&gpio_lock, flags);
1253 desc = &gpio_desc[gpio];
1255 if (chip && test_bit(FLAG_REQUESTED, &desc->flags)) {
1257 spin_unlock_irqrestore(&gpio_lock, flags);
1258 might_sleep_if(chip->can_sleep);
1259 chip->free(chip, gpio - chip->base);
1260 spin_lock_irqsave(&gpio_lock, flags);
1262 desc_set_label(desc, NULL);
1263 module_put(desc->chip->owner);
1264 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
1265 clear_bit(FLAG_REQUESTED, &desc->flags);
1267 WARN_ON(extra_checks);
1269 spin_unlock_irqrestore(&gpio_lock, flags);
1271 EXPORT_SYMBOL_GPL(gpio_free);
1274 * gpio_request_one - request a single GPIO with initial configuration
1275 * @gpio: the GPIO number
1276 * @flags: GPIO configuration as specified by GPIOF_*
1277 * @label: a literal description string of this GPIO
1279 int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
1283 err = gpio_request(gpio, label);
1287 if (flags & GPIOF_DIR_IN)
1288 err = gpio_direction_input(gpio);
1290 err = gpio_direction_output(gpio,
1291 (flags & GPIOF_INIT_HIGH) ? 1 : 0);
1298 EXPORT_SYMBOL_GPL(gpio_request_one);
1301 * gpio_request_array - request multiple GPIOs in a single call
1302 * @array: array of the 'struct gpio'
1303 * @num: how many GPIOs in the array
1305 int gpio_request_array(const struct gpio *array, size_t num)
1309 for (i = 0; i < num; i++, array++) {
1310 err = gpio_request_one(array->gpio, array->flags, array->label);
1318 gpio_free((--array)->gpio);
1321 EXPORT_SYMBOL_GPL(gpio_request_array);
1324 * gpio_free_array - release multiple GPIOs in a single call
1325 * @array: array of the 'struct gpio'
1326 * @num: how many GPIOs in the array
1328 void gpio_free_array(const struct gpio *array, size_t num)
1331 gpio_free((array++)->gpio);
1333 EXPORT_SYMBOL_GPL(gpio_free_array);
1336 * gpiochip_is_requested - return string iff signal was requested
1337 * @chip: controller managing the signal
1338 * @offset: of signal within controller's 0..(ngpio - 1) range
1340 * Returns NULL if the GPIO is not currently requested, else a string.
1341 * If debugfs support is enabled, the string returned is the label passed
1342 * to gpio_request(); otherwise it is a meaningless constant.
1344 * This function is for use by GPIO controller drivers. The label can
1345 * help with diagnostics, and knowing that the signal is used as a GPIO
1346 * can help avoid accidentally multiplexing it to another controller.
1348 const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
1350 unsigned gpio = chip->base + offset;
1352 if (!gpio_is_valid(gpio) || gpio_desc[gpio].chip != chip)
1354 if (test_bit(FLAG_REQUESTED, &gpio_desc[gpio].flags) == 0)
1356 #ifdef CONFIG_DEBUG_FS
1357 return gpio_desc[gpio].label;
1362 EXPORT_SYMBOL_GPL(gpiochip_is_requested);
1365 /* Drivers MUST set GPIO direction before making get/set calls. In
1366 * some cases this is done in early boot, before IRQs are enabled.
1368 * As a rule these aren't called more than once (except for drivers
1369 * using the open-drain emulation idiom) so these are natural places
1370 * to accumulate extra debugging checks. Note that we can't (yet)
1371 * rely on gpio_request() having been called beforehand.
1374 int gpio_direction_input(unsigned gpio)
1376 unsigned long flags;
1377 struct gpio_chip *chip;
1378 struct gpio_desc *desc = &gpio_desc[gpio];
1379 int status = -EINVAL;
1381 spin_lock_irqsave(&gpio_lock, flags);
1383 if (!gpio_is_valid(gpio))
1386 if (!chip || !chip->get || !chip->direction_input)
1389 if (gpio >= chip->ngpio)
1391 status = gpio_ensure_requested(desc, gpio);
1395 /* now we know the gpio is valid and chip won't vanish */
1397 spin_unlock_irqrestore(&gpio_lock, flags);
1399 might_sleep_if(chip->can_sleep);
1402 status = chip->request(chip, gpio);
1404 pr_debug("GPIO-%d: chip request fail, %d\n",
1405 chip->base + gpio, status);
1406 /* and it's not available to anyone else ...
1407 * gpio_request() is the fully clean solution.
1413 status = chip->direction_input(chip, gpio);
1415 clear_bit(FLAG_IS_OUT, &desc->flags);
1417 trace_gpio_direction(chip->base + gpio, 1, status);
1421 spin_unlock_irqrestore(&gpio_lock, flags);
1423 pr_debug("%s: gpio-%d status %d\n",
1424 __func__, gpio, status);
1427 EXPORT_SYMBOL_GPL(gpio_direction_input);
1429 int gpio_direction_output(unsigned gpio, int value)
1431 unsigned long flags;
1432 struct gpio_chip *chip;
1433 struct gpio_desc *desc = &gpio_desc[gpio];
1434 int status = -EINVAL;
1436 spin_lock_irqsave(&gpio_lock, flags);
1438 if (!gpio_is_valid(gpio))
1441 if (!chip || !chip->set || !chip->direction_output)
1444 if (gpio >= chip->ngpio)
1446 status = gpio_ensure_requested(desc, gpio);
1450 /* now we know the gpio is valid and chip won't vanish */
1452 spin_unlock_irqrestore(&gpio_lock, flags);
1454 might_sleep_if(chip->can_sleep);
1457 status = chip->request(chip, gpio);
1459 pr_debug("GPIO-%d: chip request fail, %d\n",
1460 chip->base + gpio, status);
1461 /* and it's not available to anyone else ...
1462 * gpio_request() is the fully clean solution.
1468 status = chip->direction_output(chip, gpio, value);
1470 set_bit(FLAG_IS_OUT, &desc->flags);
1471 trace_gpio_value(chip->base + gpio, 0, value);
1472 trace_gpio_direction(chip->base + gpio, 0, status);
1476 spin_unlock_irqrestore(&gpio_lock, flags);
1478 pr_debug("%s: gpio-%d status %d\n",
1479 __func__, gpio, status);
1482 EXPORT_SYMBOL_GPL(gpio_direction_output);
1485 * gpio_set_debounce - sets @debounce time for a @gpio
1486 * @gpio: the gpio to set debounce time
1487 * @debounce: debounce time is microseconds
1489 int gpio_set_debounce(unsigned gpio, unsigned debounce)
1491 unsigned long flags;
1492 struct gpio_chip *chip;
1493 struct gpio_desc *desc = &gpio_desc[gpio];
1494 int status = -EINVAL;
1496 spin_lock_irqsave(&gpio_lock, flags);
1498 if (!gpio_is_valid(gpio))
1501 if (!chip || !chip->set || !chip->set_debounce)
1504 if (gpio >= chip->ngpio)
1506 status = gpio_ensure_requested(desc, gpio);
1510 /* now we know the gpio is valid and chip won't vanish */
1512 spin_unlock_irqrestore(&gpio_lock, flags);
1514 might_sleep_if(chip->can_sleep);
1516 return chip->set_debounce(chip, gpio, debounce);
1519 spin_unlock_irqrestore(&gpio_lock, flags);
1521 pr_debug("%s: gpio-%d status %d\n",
1522 __func__, gpio, status);
1526 EXPORT_SYMBOL_GPL(gpio_set_debounce);
1528 /* I/O calls are only valid after configuration completed; the relevant
1529 * "is this a valid GPIO" error checks should already have been done.
1531 * "Get" operations are often inlinable as reading a pin value register,
1532 * and masking the relevant bit in that register.
1534 * When "set" operations are inlinable, they involve writing that mask to
1535 * one register to set a low value, or a different register to set it high.
1536 * Otherwise locking is needed, so there may be little value to inlining.
1538 *------------------------------------------------------------------------
1540 * IMPORTANT!!! The hot paths -- get/set value -- assume that callers
1541 * have requested the GPIO. That can include implicit requesting by
1542 * a direction setting call. Marking a gpio as requested locks its chip
1543 * in memory, guaranteeing that these table lookups need no more locking
1544 * and that gpiochip_remove() will fail.
1546 * REVISIT when debugging, consider adding some instrumentation to ensure
1547 * that the GPIO was actually requested.
1551 * __gpio_get_value() - return a gpio's value
1552 * @gpio: gpio whose value will be returned
1555 * This is used directly or indirectly to implement gpio_get_value().
1556 * It returns the zero or nonzero value provided by the associated
1557 * gpio_chip.get() method; or zero if no such method is provided.
1559 int __gpio_get_value(unsigned gpio)
1561 struct gpio_chip *chip;
1564 chip = gpio_to_chip(gpio);
1565 WARN_ON(chip->can_sleep);
1566 value = chip->get ? chip->get(chip, gpio - chip->base) : 0;
1567 trace_gpio_value(gpio, 1, value);
1570 EXPORT_SYMBOL_GPL(__gpio_get_value);
1573 * __gpio_set_value() - assign a gpio's value
1574 * @gpio: gpio whose value will be assigned
1575 * @value: value to assign
1578 * This is used directly or indirectly to implement gpio_set_value().
1579 * It invokes the associated gpio_chip.set() method.
1581 void __gpio_set_value(unsigned gpio, int value)
1583 struct gpio_chip *chip;
1585 chip = gpio_to_chip(gpio);
1586 WARN_ON(chip->can_sleep);
1587 trace_gpio_value(gpio, 0, value);
1588 chip->set(chip, gpio - chip->base, value);
1590 EXPORT_SYMBOL_GPL(__gpio_set_value);
1593 * __gpio_cansleep() - report whether gpio value access will sleep
1594 * @gpio: gpio in question
1597 * This is used directly or indirectly to implement gpio_cansleep(). It
1598 * returns nonzero if access reading or writing the GPIO value can sleep.
1600 int __gpio_cansleep(unsigned gpio)
1602 struct gpio_chip *chip;
1604 /* only call this on GPIOs that are valid! */
1605 chip = gpio_to_chip(gpio);
1607 return chip->can_sleep;
1609 EXPORT_SYMBOL_GPL(__gpio_cansleep);
1612 * __gpio_to_irq() - return the IRQ corresponding to a GPIO
1613 * @gpio: gpio whose IRQ will be returned (already requested)
1616 * This is used directly or indirectly to implement gpio_to_irq().
1617 * It returns the number of the IRQ signaled by this (input) GPIO,
1618 * or a negative errno.
1620 int __gpio_to_irq(unsigned gpio)
1622 struct gpio_chip *chip;
1624 chip = gpio_to_chip(gpio);
1625 return chip->to_irq ? chip->to_irq(chip, gpio - chip->base) : -ENXIO;
1627 EXPORT_SYMBOL_GPL(__gpio_to_irq);
1631 /* There's no value in making it easy to inline GPIO calls that may sleep.
1632 * Common examples include ones connected to I2C or SPI chips.
1635 int gpio_get_value_cansleep(unsigned gpio)
1637 struct gpio_chip *chip;
1640 might_sleep_if(extra_checks);
1641 chip = gpio_to_chip(gpio);
1642 value = chip->get ? chip->get(chip, gpio - chip->base) : 0;
1643 trace_gpio_value(gpio, 1, value);
1646 EXPORT_SYMBOL_GPL(gpio_get_value_cansleep);
1648 void gpio_set_value_cansleep(unsigned gpio, int value)
1650 struct gpio_chip *chip;
1652 might_sleep_if(extra_checks);
1653 chip = gpio_to_chip(gpio);
1654 trace_gpio_value(gpio, 0, value);
1655 chip->set(chip, gpio - chip->base, value);
1657 EXPORT_SYMBOL_GPL(gpio_set_value_cansleep);
1660 #ifdef CONFIG_DEBUG_FS
1662 static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
1665 unsigned gpio = chip->base;
1666 struct gpio_desc *gdesc = &gpio_desc[gpio];
1669 for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) {
1670 if (!test_bit(FLAG_REQUESTED, &gdesc->flags))
1673 is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
1674 seq_printf(s, " gpio-%-3d (%-20.20s) %s %s",
1676 is_out ? "out" : "in ",
1678 ? (chip->get(chip, i) ? "hi" : "lo")
1680 seq_printf(s, "\n");
1684 static int gpiolib_show(struct seq_file *s, void *unused)
1686 struct gpio_chip *chip = NULL;
1690 /* REVISIT this isn't locked against gpio_chip removal ... */
1692 for (gpio = 0; gpio_is_valid(gpio); gpio++) {
1695 if (chip == gpio_desc[gpio].chip)
1697 chip = gpio_desc[gpio].chip;
1701 seq_printf(s, "%sGPIOs %d-%d",
1702 started ? "\n" : "",
1703 chip->base, chip->base + chip->ngpio - 1);
1706 seq_printf(s, ", %s/%s",
1707 dev->bus ? dev->bus->name : "no-bus",
1710 seq_printf(s, ", %s", chip->label);
1711 if (chip->can_sleep)
1712 seq_printf(s, ", can sleep");
1713 seq_printf(s, ":\n");
1717 chip->dbg_show(s, chip);
1719 gpiolib_dbg_show(s, chip);
1724 static int gpiolib_open(struct inode *inode, struct file *file)
1726 return single_open(file, gpiolib_show, NULL);
1729 static const struct file_operations gpiolib_operations = {
1730 .open = gpiolib_open,
1732 .llseek = seq_lseek,
1733 .release = single_release,
1736 static int __init gpiolib_debugfs_init(void)
1738 /* /sys/kernel/debug/gpio */
1739 (void) debugfs_create_file("gpio", S_IFREG | S_IRUGO,
1740 NULL, NULL, &gpiolib_operations);
1743 subsys_initcall(gpiolib_debugfs_init);
1745 #endif /* DEBUG_FS */