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/idr.h>
14 /* Optional implementation infrastructure for GPIO interfaces.
16 * Platforms may want to use this if they tend to use very many GPIOs
17 * that aren't part of a System-On-Chip core; or across I2C/SPI/etc.
19 * When kernel footprint or instruction count is an issue, simpler
20 * implementations may be preferred. The GPIO programming interface
21 * allows for inlining speed-critical get/set operations for common
22 * cases, so that access to SOC-integrated GPIOs can sometimes cost
23 * only an instruction or two per bit.
27 /* When debugging, extend minimal trust to callers and platform code.
28 * Also emit diagnostic messages that may help initial bringup, when
29 * board setup or driver bugs are most common.
31 * Otherwise, minimize overhead in what may be bitbanging codepaths.
34 #define extra_checks 1
36 #define extra_checks 0
39 /* gpio_lock prevents conflicts during gpio_desc[] table updates.
40 * While any GPIO is requested, its gpio_chip is not removable;
41 * each GPIO's "requested" flag serves as a lock and refcount.
43 static DEFINE_SPINLOCK(gpio_lock);
46 struct gpio_chip *chip;
48 /* flag symbols are bit numbers */
49 #define FLAG_REQUESTED 0
51 #define FLAG_RESERVED 2
52 #define FLAG_EXPORT 3 /* protected by sysfs_lock */
53 #define FLAG_SYSFS 4 /* exported via /sys/class/gpio/control */
54 #define FLAG_TRIG_FALL 5 /* trigger on falling edge */
55 #define FLAG_TRIG_RISE 6 /* trigger on rising edge */
56 #define FLAG_ACTIVE_LOW 7 /* sysfs value has active low */
58 #define PDESC_ID_SHIFT 16 /* add new flags before this one */
60 #define GPIO_FLAGS_MASK ((1 << PDESC_ID_SHIFT) - 1)
61 #define GPIO_TRIGGER_MASK (BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE))
63 #ifdef CONFIG_DEBUG_FS
67 static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];
69 #ifdef CONFIG_GPIO_SYSFS
71 struct work_struct work;
72 struct sysfs_dirent *value_sd;
75 static struct idr pdesc_idr;
78 static inline void desc_set_label(struct gpio_desc *d, const char *label)
80 #ifdef CONFIG_DEBUG_FS
85 /* Warn when drivers omit gpio_request() calls -- legal but ill-advised
86 * when setting direction, and otherwise illegal. Until board setup code
87 * and drivers use explicit requests everywhere (which won't happen when
88 * those calls have no teeth) we can't avoid autorequesting. This nag
89 * message should motivate switching to explicit requests... so should
90 * the weaker cleanup after faults, compared to gpio_request().
92 * NOTE: the autorequest mechanism is going away; at this point it's
93 * only "legal" in the sense that (old) code using it won't break yet,
94 * but instead only triggers a WARN() stack dump.
96 static int gpio_ensure_requested(struct gpio_desc *desc, unsigned offset)
98 const struct gpio_chip *chip = desc->chip;
99 const int gpio = chip->base + offset;
101 if (WARN(test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0,
102 "autorequest GPIO-%d\n", gpio)) {
103 if (!try_module_get(chip->owner)) {
104 pr_err("GPIO-%d: module can't be gotten \n", gpio);
105 clear_bit(FLAG_REQUESTED, &desc->flags);
109 desc_set_label(desc, "[auto]");
110 /* caller must chip->request() w/o spinlock */
117 /* caller holds gpio_lock *OR* gpio is marked as requested */
118 static inline struct gpio_chip *gpio_to_chip(unsigned gpio)
120 return gpio_desc[gpio].chip;
123 /* dynamic allocation of GPIOs, e.g. on a hotplugged device */
124 static int gpiochip_find_base(int ngpio)
130 for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) {
131 struct gpio_desc *desc = &gpio_desc[i];
132 struct gpio_chip *chip = desc->chip;
134 if (!chip && !test_bit(FLAG_RESERVED, &desc->flags)) {
136 if (spare == ngpio) {
143 i -= chip->ngpio - 1;
147 if (gpio_is_valid(base))
148 pr_debug("%s: found new base at %d\n", __func__, base);
153 * gpiochip_reserve() - reserve range of gpios to use with platform code only
154 * @start: starting gpio number
155 * @ngpio: number of gpios to reserve
156 * Context: platform init, potentially before irqs or kmalloc will work
158 * Returns a negative errno if any gpio within the range is already reserved
159 * or registered, else returns zero as a success code. Use this function
160 * to mark a range of gpios as unavailable for dynamic gpio number allocation,
161 * for example because its driver support is not yet loaded.
163 int __init gpiochip_reserve(int start, int ngpio)
169 if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio - 1))
172 spin_lock_irqsave(&gpio_lock, flags);
174 for (i = start; i < start + ngpio; i++) {
175 struct gpio_desc *desc = &gpio_desc[i];
177 if (desc->chip || test_bit(FLAG_RESERVED, &desc->flags)) {
182 set_bit(FLAG_RESERVED, &desc->flags);
185 pr_debug("%s: reserved gpios from %d to %d\n",
186 __func__, start, start + ngpio - 1);
188 spin_unlock_irqrestore(&gpio_lock, flags);
193 #ifdef CONFIG_GPIO_SYSFS
195 /* lock protects against unexport_gpio() being called while
196 * sysfs files are active.
198 static DEFINE_MUTEX(sysfs_lock);
201 * /sys/class/gpio/gpioN... only for GPIOs that are exported
203 * * MAY BE OMITTED if kernel won't allow direction changes
204 * * is read/write as "in" or "out"
205 * * may also be written as "high" or "low", initializing
206 * output value as specified ("out" implies "low")
208 * * always readable, subject to hardware behavior
209 * * may be writable, as zero/nonzero
211 * * configures behavior of poll(2) on /value
212 * * available only if pin can generate IRQs on input
213 * * is read/write as "none", "falling", "rising", or "both"
215 * * configures polarity of /value
216 * * is read/write as zero/nonzero
217 * * also affects existing and subsequent "falling" and "rising"
218 * /edge configuration
221 static ssize_t gpio_direction_show(struct device *dev,
222 struct device_attribute *attr, char *buf)
224 const struct gpio_desc *desc = dev_get_drvdata(dev);
227 mutex_lock(&sysfs_lock);
229 if (!test_bit(FLAG_EXPORT, &desc->flags))
232 status = sprintf(buf, "%s\n",
233 test_bit(FLAG_IS_OUT, &desc->flags)
236 mutex_unlock(&sysfs_lock);
240 static ssize_t gpio_direction_store(struct device *dev,
241 struct device_attribute *attr, const char *buf, size_t size)
243 const struct gpio_desc *desc = dev_get_drvdata(dev);
244 unsigned gpio = desc - gpio_desc;
247 mutex_lock(&sysfs_lock);
249 if (!test_bit(FLAG_EXPORT, &desc->flags))
251 else if (sysfs_streq(buf, "high"))
252 status = gpio_direction_output(gpio, 1);
253 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
254 status = gpio_direction_output(gpio, 0);
255 else if (sysfs_streq(buf, "in"))
256 status = gpio_direction_input(gpio);
260 mutex_unlock(&sysfs_lock);
261 return status ? : size;
264 static /* const */ DEVICE_ATTR(direction, 0644,
265 gpio_direction_show, gpio_direction_store);
267 static ssize_t gpio_value_show(struct device *dev,
268 struct device_attribute *attr, char *buf)
270 const struct gpio_desc *desc = dev_get_drvdata(dev);
271 unsigned gpio = desc - gpio_desc;
274 mutex_lock(&sysfs_lock);
276 if (!test_bit(FLAG_EXPORT, &desc->flags)) {
281 value = !!gpio_get_value_cansleep(gpio);
282 if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
285 status = sprintf(buf, "%d\n", value);
288 mutex_unlock(&sysfs_lock);
292 static ssize_t gpio_value_store(struct device *dev,
293 struct device_attribute *attr, const char *buf, size_t size)
295 const struct gpio_desc *desc = dev_get_drvdata(dev);
296 unsigned gpio = desc - gpio_desc;
299 mutex_lock(&sysfs_lock);
301 if (!test_bit(FLAG_EXPORT, &desc->flags))
303 else if (!test_bit(FLAG_IS_OUT, &desc->flags))
308 status = strict_strtol(buf, 0, &value);
310 if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
312 gpio_set_value_cansleep(gpio, value != 0);
317 mutex_unlock(&sysfs_lock);
321 static const DEVICE_ATTR(value, 0644,
322 gpio_value_show, gpio_value_store);
324 static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
326 struct work_struct *work = priv;
332 static void gpio_notify_sysfs(struct work_struct *work)
334 struct poll_desc *pdesc;
336 pdesc = container_of(work, struct poll_desc, work);
337 sysfs_notify_dirent(pdesc->value_sd);
340 static int gpio_setup_irq(struct gpio_desc *desc, struct device *dev,
341 unsigned long gpio_flags)
343 struct poll_desc *pdesc;
344 unsigned long irq_flags;
347 if ((desc->flags & GPIO_TRIGGER_MASK) == gpio_flags)
350 irq = gpio_to_irq(desc - gpio_desc);
354 id = desc->flags >> PDESC_ID_SHIFT;
355 pdesc = idr_find(&pdesc_idr, id);
357 free_irq(irq, &pdesc->work);
358 cancel_work_sync(&pdesc->work);
361 desc->flags &= ~GPIO_TRIGGER_MASK;
368 irq_flags = IRQF_SHARED;
369 if (test_bit(FLAG_TRIG_FALL, &gpio_flags))
370 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
371 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
372 if (test_bit(FLAG_TRIG_RISE, &gpio_flags))
373 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
374 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
377 pdesc = kmalloc(sizeof(*pdesc), GFP_KERNEL);
385 if (idr_pre_get(&pdesc_idr, GFP_KERNEL))
386 ret = idr_get_new_above(&pdesc_idr,
388 } while (ret == -EAGAIN);
393 desc->flags &= GPIO_FLAGS_MASK;
394 desc->flags |= (unsigned long)id << PDESC_ID_SHIFT;
396 if (desc->flags >> PDESC_ID_SHIFT != id) {
401 pdesc->value_sd = sysfs_get_dirent(dev->kobj.sd, "value");
402 if (!pdesc->value_sd) {
406 INIT_WORK(&pdesc->work, gpio_notify_sysfs);
409 ret = request_irq(irq, gpio_sysfs_irq, irq_flags,
410 "gpiolib", &pdesc->work);
414 desc->flags |= gpio_flags;
418 sysfs_put(pdesc->value_sd);
420 idr_remove(&pdesc_idr, id);
421 desc->flags &= GPIO_FLAGS_MASK;
428 static const struct {
431 } trigger_types[] = {
433 { "falling", BIT(FLAG_TRIG_FALL) },
434 { "rising", BIT(FLAG_TRIG_RISE) },
435 { "both", BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE) },
438 static ssize_t gpio_edge_show(struct device *dev,
439 struct device_attribute *attr, char *buf)
441 const struct gpio_desc *desc = dev_get_drvdata(dev);
444 mutex_lock(&sysfs_lock);
446 if (!test_bit(FLAG_EXPORT, &desc->flags))
452 for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
453 if ((desc->flags & GPIO_TRIGGER_MASK)
454 == trigger_types[i].flags) {
455 status = sprintf(buf, "%s\n",
456 trigger_types[i].name);
461 mutex_unlock(&sysfs_lock);
465 static ssize_t gpio_edge_store(struct device *dev,
466 struct device_attribute *attr, const char *buf, size_t size)
468 struct gpio_desc *desc = dev_get_drvdata(dev);
472 for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
473 if (sysfs_streq(trigger_types[i].name, buf))
478 mutex_lock(&sysfs_lock);
480 if (!test_bit(FLAG_EXPORT, &desc->flags))
483 status = gpio_setup_irq(desc, dev, trigger_types[i].flags);
488 mutex_unlock(&sysfs_lock);
493 static DEVICE_ATTR(edge, 0644, gpio_edge_show, gpio_edge_store);
495 static int sysfs_set_active_low(struct gpio_desc *desc, struct device *dev,
500 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
504 set_bit(FLAG_ACTIVE_LOW, &desc->flags);
506 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
508 /* reconfigure poll(2) support if enabled on one edge only */
509 if (dev != NULL && (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^
510 !!test_bit(FLAG_TRIG_FALL, &desc->flags))) {
511 unsigned long trigger_flags = desc->flags & GPIO_TRIGGER_MASK;
513 gpio_setup_irq(desc, dev, 0);
514 status = gpio_setup_irq(desc, dev, trigger_flags);
520 static ssize_t gpio_active_low_show(struct device *dev,
521 struct device_attribute *attr, char *buf)
523 const struct gpio_desc *desc = dev_get_drvdata(dev);
526 mutex_lock(&sysfs_lock);
528 if (!test_bit(FLAG_EXPORT, &desc->flags))
531 status = sprintf(buf, "%d\n",
532 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
534 mutex_unlock(&sysfs_lock);
539 static ssize_t gpio_active_low_store(struct device *dev,
540 struct device_attribute *attr, const char *buf, size_t size)
542 struct gpio_desc *desc = dev_get_drvdata(dev);
545 mutex_lock(&sysfs_lock);
547 if (!test_bit(FLAG_EXPORT, &desc->flags)) {
552 status = strict_strtol(buf, 0, &value);
554 status = sysfs_set_active_low(desc, dev, value != 0);
557 mutex_unlock(&sysfs_lock);
559 return status ? : size;
562 static const DEVICE_ATTR(active_low, 0644,
563 gpio_active_low_show, gpio_active_low_store);
565 static const struct attribute *gpio_attrs[] = {
566 &dev_attr_value.attr,
567 &dev_attr_active_low.attr,
571 static const struct attribute_group gpio_attr_group = {
572 .attrs = (struct attribute **) gpio_attrs,
576 * /sys/class/gpio/gpiochipN/
577 * /base ... matching gpio_chip.base (N)
578 * /label ... matching gpio_chip.label
579 * /ngpio ... matching gpio_chip.ngpio
582 static ssize_t chip_base_show(struct device *dev,
583 struct device_attribute *attr, char *buf)
585 const struct gpio_chip *chip = dev_get_drvdata(dev);
587 return sprintf(buf, "%d\n", chip->base);
589 static DEVICE_ATTR(base, 0444, chip_base_show, NULL);
591 static ssize_t chip_label_show(struct device *dev,
592 struct device_attribute *attr, char *buf)
594 const struct gpio_chip *chip = dev_get_drvdata(dev);
596 return sprintf(buf, "%s\n", chip->label ? : "");
598 static DEVICE_ATTR(label, 0444, chip_label_show, NULL);
600 static ssize_t chip_ngpio_show(struct device *dev,
601 struct device_attribute *attr, char *buf)
603 const struct gpio_chip *chip = dev_get_drvdata(dev);
605 return sprintf(buf, "%u\n", chip->ngpio);
607 static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL);
609 static const struct attribute *gpiochip_attrs[] = {
611 &dev_attr_label.attr,
612 &dev_attr_ngpio.attr,
616 static const struct attribute_group gpiochip_attr_group = {
617 .attrs = (struct attribute **) gpiochip_attrs,
621 * /sys/class/gpio/export ... write-only
622 * integer N ... number of GPIO to export (full access)
623 * /sys/class/gpio/unexport ... write-only
624 * integer N ... number of GPIO to unexport
626 static ssize_t export_store(struct class *class, const char *buf, size_t len)
631 status = strict_strtol(buf, 0, &gpio);
635 /* No extra locking here; FLAG_SYSFS just signifies that the
636 * request and export were done by on behalf of userspace, so
637 * they may be undone on its behalf too.
640 status = gpio_request(gpio, "sysfs");
644 status = gpio_export(gpio, true);
648 set_bit(FLAG_SYSFS, &gpio_desc[gpio].flags);
652 pr_debug("%s: status %d\n", __func__, status);
653 return status ? : len;
656 static ssize_t unexport_store(struct class *class, const char *buf, size_t len)
661 status = strict_strtol(buf, 0, &gpio);
667 /* reject bogus commands (gpio_unexport ignores them) */
668 if (!gpio_is_valid(gpio))
671 /* No extra locking here; FLAG_SYSFS just signifies that the
672 * request and export were done by on behalf of userspace, so
673 * they may be undone on its behalf too.
675 if (test_and_clear_bit(FLAG_SYSFS, &gpio_desc[gpio].flags)) {
681 pr_debug("%s: status %d\n", __func__, status);
682 return status ? : len;
685 static struct class_attribute gpio_class_attrs[] = {
686 __ATTR(export, 0200, NULL, export_store),
687 __ATTR(unexport, 0200, NULL, unexport_store),
691 static struct class gpio_class = {
693 .owner = THIS_MODULE,
695 .class_attrs = gpio_class_attrs,
700 * gpio_export - export a GPIO through sysfs
701 * @gpio: gpio to make available, already requested
702 * @direction_may_change: true if userspace may change gpio direction
703 * Context: arch_initcall or later
705 * When drivers want to make a GPIO accessible to userspace after they
706 * have requested it -- perhaps while debugging, or as part of their
707 * public interface -- they may use this routine. If the GPIO can
708 * change direction (some can't) and the caller allows it, userspace
709 * will see "direction" sysfs attribute which may be used to change
710 * the gpio's direction. A "value" attribute will always be provided.
712 * Returns zero on success, else an error.
714 int gpio_export(unsigned gpio, bool direction_may_change)
717 struct gpio_desc *desc;
718 int status = -EINVAL;
721 /* can't export until sysfs is available ... */
723 pr_debug("%s: called too early!\n", __func__);
727 if (!gpio_is_valid(gpio))
730 mutex_lock(&sysfs_lock);
732 spin_lock_irqsave(&gpio_lock, flags);
733 desc = &gpio_desc[gpio];
734 if (test_bit(FLAG_REQUESTED, &desc->flags)
735 && !test_bit(FLAG_EXPORT, &desc->flags)) {
737 if (!desc->chip->direction_input
738 || !desc->chip->direction_output)
739 direction_may_change = false;
741 spin_unlock_irqrestore(&gpio_lock, flags);
743 if (desc->chip->names && desc->chip->names[gpio - desc->chip->base])
744 ioname = desc->chip->names[gpio - desc->chip->base];
749 dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
750 desc, ioname ? ioname : "gpio%d", gpio);
752 status = sysfs_create_group(&dev->kobj,
755 if (!status && direction_may_change)
756 status = device_create_file(dev,
757 &dev_attr_direction);
759 if (!status && gpio_to_irq(gpio) >= 0
760 && (direction_may_change
761 || !test_bit(FLAG_IS_OUT,
763 status = device_create_file(dev,
767 device_unregister(dev);
769 status = PTR_ERR(dev);
771 set_bit(FLAG_EXPORT, &desc->flags);
774 mutex_unlock(&sysfs_lock);
778 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
782 EXPORT_SYMBOL_GPL(gpio_export);
784 static int match_export(struct device *dev, void *data)
786 return dev_get_drvdata(dev) == data;
790 * gpio_export_link - create a sysfs link to an exported GPIO node
791 * @dev: device under which to create symlink
792 * @name: name of the symlink
793 * @gpio: gpio to create symlink to, already exported
795 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
796 * node. Caller is responsible for unlinking.
798 * Returns zero on success, else an error.
800 int gpio_export_link(struct device *dev, const char *name, unsigned gpio)
802 struct gpio_desc *desc;
803 int status = -EINVAL;
805 if (!gpio_is_valid(gpio))
808 mutex_lock(&sysfs_lock);
810 desc = &gpio_desc[gpio];
812 if (test_bit(FLAG_EXPORT, &desc->flags)) {
815 tdev = class_find_device(&gpio_class, NULL, desc, match_export);
817 status = sysfs_create_link(&dev->kobj, &tdev->kobj,
824 mutex_unlock(&sysfs_lock);
828 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
832 EXPORT_SYMBOL_GPL(gpio_export_link);
836 * gpio_sysfs_set_active_low - set the polarity of gpio sysfs value
837 * @gpio: gpio to change
838 * @value: non-zero to use active low, i.e. inverted values
840 * Set the polarity of /sys/class/gpio/gpioN/value sysfs attribute.
841 * The GPIO does not have to be exported yet. If poll(2) support has
842 * been enabled for either rising or falling edge, it will be
843 * reconfigured to follow the new polarity.
845 * Returns zero on success, else an error.
847 int gpio_sysfs_set_active_low(unsigned gpio, int value)
849 struct gpio_desc *desc;
850 struct device *dev = NULL;
851 int status = -EINVAL;
853 if (!gpio_is_valid(gpio))
856 mutex_lock(&sysfs_lock);
858 desc = &gpio_desc[gpio];
860 if (test_bit(FLAG_EXPORT, &desc->flags)) {
861 dev = class_find_device(&gpio_class, NULL, desc, match_export);
868 status = sysfs_set_active_low(desc, dev, value);
871 mutex_unlock(&sysfs_lock);
875 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
879 EXPORT_SYMBOL_GPL(gpio_sysfs_set_active_low);
882 * gpio_unexport - reverse effect of gpio_export()
883 * @gpio: gpio to make unavailable
885 * This is implicit on gpio_free().
887 void gpio_unexport(unsigned gpio)
889 struct gpio_desc *desc;
890 int status = -EINVAL;
892 if (!gpio_is_valid(gpio))
895 mutex_lock(&sysfs_lock);
897 desc = &gpio_desc[gpio];
899 if (test_bit(FLAG_EXPORT, &desc->flags)) {
900 struct device *dev = NULL;
902 dev = class_find_device(&gpio_class, NULL, desc, match_export);
904 gpio_setup_irq(desc, dev, 0);
905 clear_bit(FLAG_EXPORT, &desc->flags);
907 device_unregister(dev);
913 mutex_unlock(&sysfs_lock);
916 pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
918 EXPORT_SYMBOL_GPL(gpio_unexport);
920 static int gpiochip_export(struct gpio_chip *chip)
925 /* Many systems register gpio chips for SOC support very early,
926 * before driver model support is available. In those cases we
927 * export this later, in gpiolib_sysfs_init() ... here we just
928 * verify that _some_ field of gpio_class got initialized.
933 /* use chip->base for the ID; it's already known to be unique */
934 mutex_lock(&sysfs_lock);
935 dev = device_create(&gpio_class, chip->dev, MKDEV(0, 0), chip,
936 "gpiochip%d", chip->base);
938 status = sysfs_create_group(&dev->kobj,
939 &gpiochip_attr_group);
941 status = PTR_ERR(dev);
942 chip->exported = (status == 0);
943 mutex_unlock(&sysfs_lock);
949 spin_lock_irqsave(&gpio_lock, flags);
951 while (gpio_desc[gpio].chip == chip)
952 gpio_desc[gpio++].chip = NULL;
953 spin_unlock_irqrestore(&gpio_lock, flags);
955 pr_debug("%s: chip %s status %d\n", __func__,
956 chip->label, status);
962 static void gpiochip_unexport(struct gpio_chip *chip)
967 mutex_lock(&sysfs_lock);
968 dev = class_find_device(&gpio_class, NULL, chip, match_export);
971 device_unregister(dev);
976 mutex_unlock(&sysfs_lock);
979 pr_debug("%s: chip %s status %d\n", __func__,
980 chip->label, status);
983 static int __init gpiolib_sysfs_init(void)
989 idr_init(&pdesc_idr);
991 status = class_register(&gpio_class);
995 /* Scan and register the gpio_chips which registered very
996 * early (e.g. before the class_register above was called).
998 * We run before arch_initcall() so chip->dev nodes can have
999 * registered, and so arch_initcall() can always gpio_export().
1001 spin_lock_irqsave(&gpio_lock, flags);
1002 for (gpio = 0; gpio < ARCH_NR_GPIOS; gpio++) {
1003 struct gpio_chip *chip;
1005 chip = gpio_desc[gpio].chip;
1006 if (!chip || chip->exported)
1009 spin_unlock_irqrestore(&gpio_lock, flags);
1010 status = gpiochip_export(chip);
1011 spin_lock_irqsave(&gpio_lock, flags);
1013 spin_unlock_irqrestore(&gpio_lock, flags);
1018 postcore_initcall(gpiolib_sysfs_init);
1021 static inline int gpiochip_export(struct gpio_chip *chip)
1026 static inline void gpiochip_unexport(struct gpio_chip *chip)
1030 #endif /* CONFIG_GPIO_SYSFS */
1033 * gpiochip_add() - register a gpio_chip
1034 * @chip: the chip to register, with chip->base initialized
1035 * Context: potentially before irqs or kmalloc will work
1037 * Returns a negative errno if the chip can't be registered, such as
1038 * because the chip->base is invalid or already associated with a
1039 * different chip. Otherwise it returns zero as a success code.
1041 * When gpiochip_add() is called very early during boot, so that GPIOs
1042 * can be freely used, the chip->dev device must be registered before
1043 * the gpio framework's arch_initcall(). Otherwise sysfs initialization
1044 * for GPIOs will fail rudely.
1046 * If chip->base is negative, this requests dynamic assignment of
1047 * a range of valid GPIOs.
1049 int gpiochip_add(struct gpio_chip *chip)
1051 unsigned long flags;
1054 int base = chip->base;
1056 if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
1062 spin_lock_irqsave(&gpio_lock, flags);
1065 base = gpiochip_find_base(chip->ngpio);
1073 /* these GPIO numbers must not be managed by another gpio_chip */
1074 for (id = base; id < base + chip->ngpio; id++) {
1075 if (gpio_desc[id].chip != NULL) {
1081 for (id = base; id < base + chip->ngpio; id++) {
1082 gpio_desc[id].chip = chip;
1084 /* REVISIT: most hardware initializes GPIOs as
1085 * inputs (often with pullups enabled) so power
1086 * usage is minimized. Linux code should set the
1087 * gpio direction first thing; but until it does,
1088 * we may expose the wrong direction in sysfs.
1090 gpio_desc[id].flags = !chip->direction_input
1091 ? (1 << FLAG_IS_OUT)
1097 spin_unlock_irqrestore(&gpio_lock, flags);
1099 status = gpiochip_export(chip);
1101 /* failures here can mean systems won't boot... */
1103 pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n",
1104 chip->base, chip->base + chip->ngpio - 1,
1105 chip->label ? : "generic");
1108 EXPORT_SYMBOL_GPL(gpiochip_add);
1111 * gpiochip_remove() - unregister a gpio_chip
1112 * @chip: the chip to unregister
1114 * A gpio_chip with any GPIOs still requested may not be removed.
1116 int gpiochip_remove(struct gpio_chip *chip)
1118 unsigned long flags;
1122 spin_lock_irqsave(&gpio_lock, flags);
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 /* These "optional" allocation calls help prevent drivers from stomping
1146 * on each other, and help provide better diagnostics in debugfs.
1147 * They're called even less than the "set direction" calls.
1149 int gpio_request(unsigned gpio, const char *label)
1151 struct gpio_desc *desc;
1152 struct gpio_chip *chip;
1153 int status = -EINVAL;
1154 unsigned long flags;
1156 spin_lock_irqsave(&gpio_lock, flags);
1158 if (!gpio_is_valid(gpio))
1160 desc = &gpio_desc[gpio];
1165 if (!try_module_get(chip->owner))
1168 /* NOTE: gpio_request() can be called in early boot,
1169 * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
1172 if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
1173 desc_set_label(desc, label ? : "?");
1177 module_put(chip->owner);
1181 if (chip->request) {
1182 /* chip->request may sleep */
1183 spin_unlock_irqrestore(&gpio_lock, flags);
1184 status = chip->request(chip, gpio - chip->base);
1185 spin_lock_irqsave(&gpio_lock, flags);
1188 desc_set_label(desc, NULL);
1189 module_put(chip->owner);
1190 clear_bit(FLAG_REQUESTED, &desc->flags);
1196 pr_debug("gpio_request: gpio-%d (%s) status %d\n",
1197 gpio, label ? : "?", status);
1198 spin_unlock_irqrestore(&gpio_lock, flags);
1201 EXPORT_SYMBOL_GPL(gpio_request);
1203 void gpio_free(unsigned gpio)
1205 unsigned long flags;
1206 struct gpio_desc *desc;
1207 struct gpio_chip *chip;
1211 if (!gpio_is_valid(gpio)) {
1212 WARN_ON(extra_checks);
1216 gpio_unexport(gpio);
1218 spin_lock_irqsave(&gpio_lock, flags);
1220 desc = &gpio_desc[gpio];
1222 if (chip && test_bit(FLAG_REQUESTED, &desc->flags)) {
1224 spin_unlock_irqrestore(&gpio_lock, flags);
1225 might_sleep_if(extra_checks && chip->can_sleep);
1226 chip->free(chip, gpio - chip->base);
1227 spin_lock_irqsave(&gpio_lock, flags);
1229 desc_set_label(desc, NULL);
1230 module_put(desc->chip->owner);
1231 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
1232 clear_bit(FLAG_REQUESTED, &desc->flags);
1234 WARN_ON(extra_checks);
1236 spin_unlock_irqrestore(&gpio_lock, flags);
1238 EXPORT_SYMBOL_GPL(gpio_free);
1242 * gpiochip_is_requested - return string iff signal was requested
1243 * @chip: controller managing the signal
1244 * @offset: of signal within controller's 0..(ngpio - 1) range
1246 * Returns NULL if the GPIO is not currently requested, else a string.
1247 * If debugfs support is enabled, the string returned is the label passed
1248 * to gpio_request(); otherwise it is a meaningless constant.
1250 * This function is for use by GPIO controller drivers. The label can
1251 * help with diagnostics, and knowing that the signal is used as a GPIO
1252 * can help avoid accidentally multiplexing it to another controller.
1254 const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
1256 unsigned gpio = chip->base + offset;
1258 if (!gpio_is_valid(gpio) || gpio_desc[gpio].chip != chip)
1260 if (test_bit(FLAG_REQUESTED, &gpio_desc[gpio].flags) == 0)
1262 #ifdef CONFIG_DEBUG_FS
1263 return gpio_desc[gpio].label;
1268 EXPORT_SYMBOL_GPL(gpiochip_is_requested);
1271 /* Drivers MUST set GPIO direction before making get/set calls. In
1272 * some cases this is done in early boot, before IRQs are enabled.
1274 * As a rule these aren't called more than once (except for drivers
1275 * using the open-drain emulation idiom) so these are natural places
1276 * to accumulate extra debugging checks. Note that we can't (yet)
1277 * rely on gpio_request() having been called beforehand.
1280 int gpio_direction_input(unsigned gpio)
1282 unsigned long flags;
1283 struct gpio_chip *chip;
1284 struct gpio_desc *desc = &gpio_desc[gpio];
1285 int status = -EINVAL;
1287 spin_lock_irqsave(&gpio_lock, flags);
1289 if (!gpio_is_valid(gpio))
1292 if (!chip || !chip->get || !chip->direction_input)
1295 if (gpio >= chip->ngpio)
1297 status = gpio_ensure_requested(desc, gpio);
1301 /* now we know the gpio is valid and chip won't vanish */
1303 spin_unlock_irqrestore(&gpio_lock, flags);
1305 might_sleep_if(extra_checks && chip->can_sleep);
1308 status = chip->request(chip, gpio);
1310 pr_debug("GPIO-%d: chip request fail, %d\n",
1311 chip->base + gpio, status);
1312 /* and it's not available to anyone else ...
1313 * gpio_request() is the fully clean solution.
1319 status = chip->direction_input(chip, gpio);
1321 clear_bit(FLAG_IS_OUT, &desc->flags);
1325 spin_unlock_irqrestore(&gpio_lock, flags);
1327 pr_debug("%s: gpio-%d status %d\n",
1328 __func__, gpio, status);
1331 EXPORT_SYMBOL_GPL(gpio_direction_input);
1333 int gpio_direction_output(unsigned gpio, int value)
1335 unsigned long flags;
1336 struct gpio_chip *chip;
1337 struct gpio_desc *desc = &gpio_desc[gpio];
1338 int status = -EINVAL;
1340 spin_lock_irqsave(&gpio_lock, flags);
1342 if (!gpio_is_valid(gpio))
1345 if (!chip || !chip->set || !chip->direction_output)
1348 if (gpio >= chip->ngpio)
1350 status = gpio_ensure_requested(desc, gpio);
1354 /* now we know the gpio is valid and chip won't vanish */
1356 spin_unlock_irqrestore(&gpio_lock, flags);
1358 might_sleep_if(extra_checks && chip->can_sleep);
1361 status = chip->request(chip, gpio);
1363 pr_debug("GPIO-%d: chip request fail, %d\n",
1364 chip->base + gpio, status);
1365 /* and it's not available to anyone else ...
1366 * gpio_request() is the fully clean solution.
1372 status = chip->direction_output(chip, gpio, value);
1374 set_bit(FLAG_IS_OUT, &desc->flags);
1378 spin_unlock_irqrestore(&gpio_lock, flags);
1380 pr_debug("%s: gpio-%d status %d\n",
1381 __func__, gpio, status);
1384 EXPORT_SYMBOL_GPL(gpio_direction_output);
1387 /* I/O calls are only valid after configuration completed; the relevant
1388 * "is this a valid GPIO" error checks should already have been done.
1390 * "Get" operations are often inlinable as reading a pin value register,
1391 * and masking the relevant bit in that register.
1393 * When "set" operations are inlinable, they involve writing that mask to
1394 * one register to set a low value, or a different register to set it high.
1395 * Otherwise locking is needed, so there may be little value to inlining.
1397 *------------------------------------------------------------------------
1399 * IMPORTANT!!! The hot paths -- get/set value -- assume that callers
1400 * have requested the GPIO. That can include implicit requesting by
1401 * a direction setting call. Marking a gpio as requested locks its chip
1402 * in memory, guaranteeing that these table lookups need no more locking
1403 * and that gpiochip_remove() will fail.
1405 * REVISIT when debugging, consider adding some instrumentation to ensure
1406 * that the GPIO was actually requested.
1410 * __gpio_get_value() - return a gpio's value
1411 * @gpio: gpio whose value will be returned
1414 * This is used directly or indirectly to implement gpio_get_value().
1415 * It returns the zero or nonzero value provided by the associated
1416 * gpio_chip.get() method; or zero if no such method is provided.
1418 int __gpio_get_value(unsigned gpio)
1420 struct gpio_chip *chip;
1422 chip = gpio_to_chip(gpio);
1423 WARN_ON(extra_checks && chip->can_sleep);
1424 return chip->get ? chip->get(chip, gpio - chip->base) : 0;
1426 EXPORT_SYMBOL_GPL(__gpio_get_value);
1429 * __gpio_set_value() - assign a gpio's value
1430 * @gpio: gpio whose value will be assigned
1431 * @value: value to assign
1434 * This is used directly or indirectly to implement gpio_set_value().
1435 * It invokes the associated gpio_chip.set() method.
1437 void __gpio_set_value(unsigned gpio, int value)
1439 struct gpio_chip *chip;
1441 chip = gpio_to_chip(gpio);
1442 WARN_ON(extra_checks && chip->can_sleep);
1443 chip->set(chip, gpio - chip->base, value);
1445 EXPORT_SYMBOL_GPL(__gpio_set_value);
1448 * __gpio_cansleep() - report whether gpio value access will sleep
1449 * @gpio: gpio in question
1452 * This is used directly or indirectly to implement gpio_cansleep(). It
1453 * returns nonzero if access reading or writing the GPIO value can sleep.
1455 int __gpio_cansleep(unsigned gpio)
1457 struct gpio_chip *chip;
1459 /* only call this on GPIOs that are valid! */
1460 chip = gpio_to_chip(gpio);
1462 return chip->can_sleep;
1464 EXPORT_SYMBOL_GPL(__gpio_cansleep);
1467 * __gpio_to_irq() - return the IRQ corresponding to a GPIO
1468 * @gpio: gpio whose IRQ will be returned (already requested)
1471 * This is used directly or indirectly to implement gpio_to_irq().
1472 * It returns the number of the IRQ signaled by this (input) GPIO,
1473 * or a negative errno.
1475 int __gpio_to_irq(unsigned gpio)
1477 struct gpio_chip *chip;
1479 chip = gpio_to_chip(gpio);
1480 return chip->to_irq ? chip->to_irq(chip, gpio - chip->base) : -ENXIO;
1482 EXPORT_SYMBOL_GPL(__gpio_to_irq);
1486 /* There's no value in making it easy to inline GPIO calls that may sleep.
1487 * Common examples include ones connected to I2C or SPI chips.
1490 int gpio_get_value_cansleep(unsigned gpio)
1492 struct gpio_chip *chip;
1494 might_sleep_if(extra_checks);
1495 chip = gpio_to_chip(gpio);
1496 return chip->get ? chip->get(chip, gpio - chip->base) : 0;
1498 EXPORT_SYMBOL_GPL(gpio_get_value_cansleep);
1500 void gpio_set_value_cansleep(unsigned gpio, int value)
1502 struct gpio_chip *chip;
1504 might_sleep_if(extra_checks);
1505 chip = gpio_to_chip(gpio);
1506 chip->set(chip, gpio - chip->base, value);
1508 EXPORT_SYMBOL_GPL(gpio_set_value_cansleep);
1511 #ifdef CONFIG_DEBUG_FS
1513 static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
1516 unsigned gpio = chip->base;
1517 struct gpio_desc *gdesc = &gpio_desc[gpio];
1520 for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) {
1521 if (!test_bit(FLAG_REQUESTED, &gdesc->flags))
1524 is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
1525 seq_printf(s, " gpio-%-3d (%-20.20s) %s %s",
1527 is_out ? "out" : "in ",
1529 ? (chip->get(chip, i) ? "hi" : "lo")
1533 int irq = gpio_to_irq(gpio);
1534 struct irq_desc *desc = irq_to_desc(irq);
1536 /* This races with request_irq(), set_irq_type(),
1537 * and set_irq_wake() ... but those are "rare".
1539 * More significantly, trigger type flags aren't
1540 * currently maintained by genirq.
1542 if (irq >= 0 && desc->action) {
1545 switch (desc->status & IRQ_TYPE_SENSE_MASK) {
1547 trigger = "(default)";
1549 case IRQ_TYPE_EDGE_FALLING:
1550 trigger = "edge-falling";
1552 case IRQ_TYPE_EDGE_RISING:
1553 trigger = "edge-rising";
1555 case IRQ_TYPE_EDGE_BOTH:
1556 trigger = "edge-both";
1558 case IRQ_TYPE_LEVEL_HIGH:
1559 trigger = "level-high";
1561 case IRQ_TYPE_LEVEL_LOW:
1562 trigger = "level-low";
1565 trigger = "?trigger?";
1569 seq_printf(s, " irq-%d %s%s",
1571 (desc->status & IRQ_WAKEUP)
1576 seq_printf(s, "\n");
1580 static int gpiolib_show(struct seq_file *s, void *unused)
1582 struct gpio_chip *chip = NULL;
1586 /* REVISIT this isn't locked against gpio_chip removal ... */
1588 for (gpio = 0; gpio_is_valid(gpio); gpio++) {
1591 if (chip == gpio_desc[gpio].chip)
1593 chip = gpio_desc[gpio].chip;
1597 seq_printf(s, "%sGPIOs %d-%d",
1598 started ? "\n" : "",
1599 chip->base, chip->base + chip->ngpio - 1);
1602 seq_printf(s, ", %s/%s",
1603 dev->bus ? dev->bus->name : "no-bus",
1606 seq_printf(s, ", %s", chip->label);
1607 if (chip->can_sleep)
1608 seq_printf(s, ", can sleep");
1609 seq_printf(s, ":\n");
1613 chip->dbg_show(s, chip);
1615 gpiolib_dbg_show(s, chip);
1620 static int gpiolib_open(struct inode *inode, struct file *file)
1622 return single_open(file, gpiolib_show, NULL);
1625 static const struct file_operations gpiolib_operations = {
1626 .open = gpiolib_open,
1628 .llseek = seq_lseek,
1629 .release = single_release,
1632 static int __init gpiolib_debugfs_init(void)
1634 /* /sys/kernel/debug/gpio */
1635 (void) debugfs_create_file("gpio", S_IFREG | S_IRUGO,
1636 NULL, NULL, &gpiolib_operations);
1639 subsys_initcall(gpiolib_debugfs_init);
1641 #endif /* DEBUG_FS */