2 #include <linux/mutex.h>
3 #include <linux/device.h>
4 #include <linux/sysfs.h>
5 #include <linux/gpio/consumer.h>
6 #include <linux/gpio/driver.h>
7 #include <linux/interrupt.h>
8 #include <linux/kdev_t.h>
12 static DEFINE_IDR(dirent_idr);
15 /* lock protects against unexport_gpio() being called while
16 * sysfs files are active.
18 static DEFINE_MUTEX(sysfs_lock);
21 * /sys/class/gpio/gpioN... only for GPIOs that are exported
23 * * MAY BE OMITTED if kernel won't allow direction changes
24 * * is read/write as "in" or "out"
25 * * may also be written as "high" or "low", initializing
26 * output value as specified ("out" implies "low")
28 * * always readable, subject to hardware behavior
29 * * may be writable, as zero/nonzero
31 * * configures behavior of poll(2) on /value
32 * * available only if pin can generate IRQs on input
33 * * is read/write as "none", "falling", "rising", or "both"
35 * * configures polarity of /value
36 * * is read/write as zero/nonzero
37 * * also affects existing and subsequent "falling" and "rising"
41 static ssize_t gpio_direction_show(struct device *dev,
42 struct device_attribute *attr, char *buf)
44 const struct gpio_desc *desc = dev_get_drvdata(dev);
47 mutex_lock(&sysfs_lock);
49 if (!test_bit(FLAG_EXPORT, &desc->flags)) {
52 gpiod_get_direction(desc);
53 status = sprintf(buf, "%s\n",
54 test_bit(FLAG_IS_OUT, &desc->flags)
58 mutex_unlock(&sysfs_lock);
62 static ssize_t gpio_direction_store(struct device *dev,
63 struct device_attribute *attr, const char *buf, size_t size)
65 struct gpio_desc *desc = dev_get_drvdata(dev);
68 mutex_lock(&sysfs_lock);
70 if (!test_bit(FLAG_EXPORT, &desc->flags))
72 else if (sysfs_streq(buf, "high"))
73 status = gpiod_direction_output_raw(desc, 1);
74 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
75 status = gpiod_direction_output_raw(desc, 0);
76 else if (sysfs_streq(buf, "in"))
77 status = gpiod_direction_input(desc);
81 mutex_unlock(&sysfs_lock);
82 return status ? : size;
85 static /* const */ DEVICE_ATTR(direction, 0644,
86 gpio_direction_show, gpio_direction_store);
88 static ssize_t gpio_value_show(struct device *dev,
89 struct device_attribute *attr, char *buf)
91 struct gpio_desc *desc = dev_get_drvdata(dev);
94 mutex_lock(&sysfs_lock);
96 if (!test_bit(FLAG_EXPORT, &desc->flags))
99 status = sprintf(buf, "%d\n", gpiod_get_value_cansleep(desc));
101 mutex_unlock(&sysfs_lock);
105 static ssize_t gpio_value_store(struct device *dev,
106 struct device_attribute *attr, const char *buf, size_t size)
108 struct gpio_desc *desc = dev_get_drvdata(dev);
111 mutex_lock(&sysfs_lock);
113 if (!test_bit(FLAG_EXPORT, &desc->flags))
115 else if (!test_bit(FLAG_IS_OUT, &desc->flags))
120 status = kstrtol(buf, 0, &value);
122 gpiod_set_value_cansleep(desc, value);
127 mutex_unlock(&sysfs_lock);
131 static const DEVICE_ATTR(value, 0644,
132 gpio_value_show, gpio_value_store);
134 static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
136 struct kernfs_node *value_sd = priv;
138 sysfs_notify_dirent(value_sd);
142 static int gpio_setup_irq(struct gpio_desc *desc, struct device *dev,
143 unsigned long gpio_flags)
145 struct kernfs_node *value_sd;
146 unsigned long irq_flags;
149 if ((desc->flags & GPIO_TRIGGER_MASK) == gpio_flags)
152 irq = gpiod_to_irq(desc);
156 id = desc->flags >> ID_SHIFT;
157 value_sd = idr_find(&dirent_idr, id);
159 free_irq(irq, value_sd);
161 desc->flags &= ~GPIO_TRIGGER_MASK;
164 gpio_unlock_as_irq(desc->chip, gpio_chip_hwgpio(desc));
169 irq_flags = IRQF_SHARED;
170 if (test_bit(FLAG_TRIG_FALL, &gpio_flags))
171 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
172 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
173 if (test_bit(FLAG_TRIG_RISE, &gpio_flags))
174 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
175 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
178 value_sd = sysfs_get_dirent(dev->kobj.sd, "value");
184 ret = idr_alloc(&dirent_idr, value_sd, 1, 0, GFP_KERNEL);
189 desc->flags &= GPIO_FLAGS_MASK;
190 desc->flags |= (unsigned long)id << ID_SHIFT;
192 if (desc->flags >> ID_SHIFT != id) {
198 ret = request_any_context_irq(irq, gpio_sysfs_irq, irq_flags,
199 "gpiolib", value_sd);
203 ret = gpio_lock_as_irq(desc->chip, gpio_chip_hwgpio(desc));
205 gpiod_warn(desc, "failed to flag the GPIO for IRQ\n");
209 desc->flags |= gpio_flags;
213 idr_remove(&dirent_idr, id);
214 desc->flags &= GPIO_FLAGS_MASK;
222 static const struct {
225 } trigger_types[] = {
227 { "falling", BIT(FLAG_TRIG_FALL) },
228 { "rising", BIT(FLAG_TRIG_RISE) },
229 { "both", BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE) },
232 static ssize_t gpio_edge_show(struct device *dev,
233 struct device_attribute *attr, char *buf)
235 const struct gpio_desc *desc = dev_get_drvdata(dev);
238 mutex_lock(&sysfs_lock);
240 if (!test_bit(FLAG_EXPORT, &desc->flags))
246 for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
247 if ((desc->flags & GPIO_TRIGGER_MASK)
248 == trigger_types[i].flags) {
249 status = sprintf(buf, "%s\n",
250 trigger_types[i].name);
255 mutex_unlock(&sysfs_lock);
259 static ssize_t gpio_edge_store(struct device *dev,
260 struct device_attribute *attr, const char *buf, size_t size)
262 struct gpio_desc *desc = dev_get_drvdata(dev);
266 for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
267 if (sysfs_streq(trigger_types[i].name, buf))
272 mutex_lock(&sysfs_lock);
274 if (!test_bit(FLAG_EXPORT, &desc->flags))
277 status = gpio_setup_irq(desc, dev, trigger_types[i].flags);
282 mutex_unlock(&sysfs_lock);
287 static DEVICE_ATTR(edge, 0644, gpio_edge_show, gpio_edge_store);
289 static int sysfs_set_active_low(struct gpio_desc *desc, struct device *dev,
294 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
298 set_bit(FLAG_ACTIVE_LOW, &desc->flags);
300 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
302 /* reconfigure poll(2) support if enabled on one edge only */
303 if (dev != NULL && (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^
304 !!test_bit(FLAG_TRIG_FALL, &desc->flags))) {
305 unsigned long trigger_flags = desc->flags & GPIO_TRIGGER_MASK;
307 gpio_setup_irq(desc, dev, 0);
308 status = gpio_setup_irq(desc, dev, trigger_flags);
314 static ssize_t gpio_active_low_show(struct device *dev,
315 struct device_attribute *attr, char *buf)
317 const struct gpio_desc *desc = dev_get_drvdata(dev);
320 mutex_lock(&sysfs_lock);
322 if (!test_bit(FLAG_EXPORT, &desc->flags))
325 status = sprintf(buf, "%d\n",
326 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
328 mutex_unlock(&sysfs_lock);
333 static ssize_t gpio_active_low_store(struct device *dev,
334 struct device_attribute *attr, const char *buf, size_t size)
336 struct gpio_desc *desc = dev_get_drvdata(dev);
339 mutex_lock(&sysfs_lock);
341 if (!test_bit(FLAG_EXPORT, &desc->flags)) {
346 status = kstrtol(buf, 0, &value);
348 status = sysfs_set_active_low(desc, dev, value != 0);
351 mutex_unlock(&sysfs_lock);
353 return status ? : size;
356 static const DEVICE_ATTR(active_low, 0644,
357 gpio_active_low_show, gpio_active_low_store);
359 static const struct attribute *gpio_attrs[] = {
360 &dev_attr_value.attr,
361 &dev_attr_active_low.attr,
365 static const struct attribute_group gpio_attr_group = {
366 .attrs = (struct attribute **) gpio_attrs,
370 * /sys/class/gpio/gpiochipN/
371 * /base ... matching gpio_chip.base (N)
372 * /label ... matching gpio_chip.label
373 * /ngpio ... matching gpio_chip.ngpio
376 static ssize_t chip_base_show(struct device *dev,
377 struct device_attribute *attr, char *buf)
379 const struct gpio_chip *chip = dev_get_drvdata(dev);
381 return sprintf(buf, "%d\n", chip->base);
383 static DEVICE_ATTR(base, 0444, chip_base_show, NULL);
385 static ssize_t chip_label_show(struct device *dev,
386 struct device_attribute *attr, char *buf)
388 const struct gpio_chip *chip = dev_get_drvdata(dev);
390 return sprintf(buf, "%s\n", chip->label ? : "");
392 static DEVICE_ATTR(label, 0444, chip_label_show, NULL);
394 static ssize_t chip_ngpio_show(struct device *dev,
395 struct device_attribute *attr, char *buf)
397 const struct gpio_chip *chip = dev_get_drvdata(dev);
399 return sprintf(buf, "%u\n", chip->ngpio);
401 static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL);
403 static const struct attribute *gpiochip_attrs[] = {
405 &dev_attr_label.attr,
406 &dev_attr_ngpio.attr,
410 static const struct attribute_group gpiochip_attr_group = {
411 .attrs = (struct attribute **) gpiochip_attrs,
415 * /sys/class/gpio/export ... write-only
416 * integer N ... number of GPIO to export (full access)
417 * /sys/class/gpio/unexport ... write-only
418 * integer N ... number of GPIO to unexport
420 static ssize_t export_store(struct class *class,
421 struct class_attribute *attr,
422 const char *buf, size_t len)
425 struct gpio_desc *desc;
428 status = kstrtol(buf, 0, &gpio);
432 desc = gpio_to_desc(gpio);
433 /* reject invalid GPIOs */
435 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
439 /* No extra locking here; FLAG_SYSFS just signifies that the
440 * request and export were done by on behalf of userspace, so
441 * they may be undone on its behalf too.
444 status = gpiod_request(desc, "sysfs");
446 if (status == -EPROBE_DEFER)
450 status = gpiod_export(desc, true);
454 set_bit(FLAG_SYSFS, &desc->flags);
458 pr_debug("%s: status %d\n", __func__, status);
459 return status ? : len;
462 static ssize_t unexport_store(struct class *class,
463 struct class_attribute *attr,
464 const char *buf, size_t len)
467 struct gpio_desc *desc;
470 status = kstrtol(buf, 0, &gpio);
474 desc = gpio_to_desc(gpio);
475 /* reject bogus commands (gpio_unexport ignores them) */
477 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
483 /* No extra locking here; FLAG_SYSFS just signifies that the
484 * request and export were done by on behalf of userspace, so
485 * they may be undone on its behalf too.
487 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
493 pr_debug("%s: status %d\n", __func__, status);
494 return status ? : len;
497 static struct class_attribute gpio_class_attrs[] = {
498 __ATTR(export, 0200, NULL, export_store),
499 __ATTR(unexport, 0200, NULL, unexport_store),
503 static struct class gpio_class = {
505 .owner = THIS_MODULE,
507 .class_attrs = gpio_class_attrs,
512 * gpiod_export - export a GPIO through sysfs
513 * @gpio: gpio to make available, already requested
514 * @direction_may_change: true if userspace may change gpio direction
515 * Context: arch_initcall or later
517 * When drivers want to make a GPIO accessible to userspace after they
518 * have requested it -- perhaps while debugging, or as part of their
519 * public interface -- they may use this routine. If the GPIO can
520 * change direction (some can't) and the caller allows it, userspace
521 * will see "direction" sysfs attribute which may be used to change
522 * the gpio's direction. A "value" attribute will always be provided.
524 * Returns zero on success, else an error.
526 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
530 const char *ioname = NULL;
534 /* can't export until sysfs is available ... */
536 pr_debug("%s: called too early!\n", __func__);
541 pr_debug("%s: invalid gpio descriptor\n", __func__);
545 mutex_lock(&sysfs_lock);
547 spin_lock_irqsave(&gpio_lock, flags);
548 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
549 test_bit(FLAG_EXPORT, &desc->flags)) {
550 spin_unlock_irqrestore(&gpio_lock, flags);
551 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
553 test_bit(FLAG_REQUESTED, &desc->flags),
554 test_bit(FLAG_EXPORT, &desc->flags));
559 if (!desc->chip->direction_input || !desc->chip->direction_output)
560 direction_may_change = false;
561 spin_unlock_irqrestore(&gpio_lock, flags);
563 offset = gpio_chip_hwgpio(desc);
564 if (desc->chip->names && desc->chip->names[offset])
565 ioname = desc->chip->names[offset];
567 dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
568 desc, ioname ? ioname : "gpio%u",
571 status = PTR_ERR(dev);
575 status = sysfs_create_group(&dev->kobj, &gpio_attr_group);
577 goto fail_unregister_device;
579 if (direction_may_change) {
580 status = device_create_file(dev, &dev_attr_direction);
582 goto fail_unregister_device;
585 if (gpiod_to_irq(desc) >= 0 && (direction_may_change ||
586 !test_bit(FLAG_IS_OUT, &desc->flags))) {
587 status = device_create_file(dev, &dev_attr_edge);
589 goto fail_unregister_device;
592 set_bit(FLAG_EXPORT, &desc->flags);
593 mutex_unlock(&sysfs_lock);
596 fail_unregister_device:
597 device_unregister(dev);
599 mutex_unlock(&sysfs_lock);
600 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
603 EXPORT_SYMBOL_GPL(gpiod_export);
605 static int match_export(struct device *dev, const void *data)
607 return dev_get_drvdata(dev) == data;
611 * gpiod_export_link - create a sysfs link to an exported GPIO node
612 * @dev: device under which to create symlink
613 * @name: name of the symlink
614 * @gpio: gpio to create symlink to, already exported
616 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
617 * node. Caller is responsible for unlinking.
619 * Returns zero on success, else an error.
621 int gpiod_export_link(struct device *dev, const char *name,
622 struct gpio_desc *desc)
624 int status = -EINVAL;
627 pr_warn("%s: invalid GPIO\n", __func__);
631 mutex_lock(&sysfs_lock);
633 if (test_bit(FLAG_EXPORT, &desc->flags)) {
636 tdev = class_find_device(&gpio_class, NULL, desc, match_export);
638 status = sysfs_create_link(&dev->kobj, &tdev->kobj,
645 mutex_unlock(&sysfs_lock);
648 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
652 EXPORT_SYMBOL_GPL(gpiod_export_link);
655 * gpiod_sysfs_set_active_low - set the polarity of gpio sysfs value
656 * @gpio: gpio to change
657 * @value: non-zero to use active low, i.e. inverted values
659 * Set the polarity of /sys/class/gpio/gpioN/value sysfs attribute.
660 * The GPIO does not have to be exported yet. If poll(2) support has
661 * been enabled for either rising or falling edge, it will be
662 * reconfigured to follow the new polarity.
664 * Returns zero on success, else an error.
666 int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
668 struct device *dev = NULL;
669 int status = -EINVAL;
672 pr_warn("%s: invalid GPIO\n", __func__);
676 mutex_lock(&sysfs_lock);
678 if (test_bit(FLAG_EXPORT, &desc->flags)) {
679 dev = class_find_device(&gpio_class, NULL, desc, match_export);
686 status = sysfs_set_active_low(desc, dev, value);
689 mutex_unlock(&sysfs_lock);
692 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
696 EXPORT_SYMBOL_GPL(gpiod_sysfs_set_active_low);
699 * gpiod_unexport - reverse effect of gpio_export()
700 * @gpio: gpio to make unavailable
702 * This is implicit on gpio_free().
704 void gpiod_unexport(struct gpio_desc *desc)
707 struct device *dev = NULL;
710 pr_warn("%s: invalid GPIO\n", __func__);
714 mutex_lock(&sysfs_lock);
716 if (test_bit(FLAG_EXPORT, &desc->flags)) {
718 dev = class_find_device(&gpio_class, NULL, desc, match_export);
720 gpio_setup_irq(desc, dev, 0);
721 clear_bit(FLAG_EXPORT, &desc->flags);
726 mutex_unlock(&sysfs_lock);
729 device_unregister(dev);
734 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
736 EXPORT_SYMBOL_GPL(gpiod_unexport);
738 int gpiochip_export(struct gpio_chip *chip)
743 /* Many systems register gpio chips for SOC support very early,
744 * before driver model support is available. In those cases we
745 * export this later, in gpiolib_sysfs_init() ... here we just
746 * verify that _some_ field of gpio_class got initialized.
751 /* use chip->base for the ID; it's already known to be unique */
752 mutex_lock(&sysfs_lock);
753 dev = device_create(&gpio_class, chip->dev, MKDEV(0, 0), chip,
754 "gpiochip%d", chip->base);
756 status = sysfs_create_group(&dev->kobj,
757 &gpiochip_attr_group);
759 status = PTR_ERR(dev);
760 chip->exported = (status == 0);
761 mutex_unlock(&sysfs_lock);
764 chip_dbg(chip, "%s: status %d\n", __func__, status);
769 void gpiochip_unexport(struct gpio_chip *chip)
774 mutex_lock(&sysfs_lock);
775 dev = class_find_device(&gpio_class, NULL, chip, match_export);
778 device_unregister(dev);
779 chip->exported = false;
783 mutex_unlock(&sysfs_lock);
786 chip_dbg(chip, "%s: status %d\n", __func__, status);
789 static int __init gpiolib_sysfs_init(void)
793 struct gpio_chip *chip;
795 status = class_register(&gpio_class);
799 /* Scan and register the gpio_chips which registered very
800 * early (e.g. before the class_register above was called).
802 * We run before arch_initcall() so chip->dev nodes can have
803 * registered, and so arch_initcall() can always gpio_export().
805 spin_lock_irqsave(&gpio_lock, flags);
806 list_for_each_entry(chip, &gpio_chips, list) {
811 * TODO we yield gpio_lock here because gpiochip_export()
812 * acquires a mutex. This is unsafe and needs to be fixed.
814 * Also it would be nice to use gpiochip_find() here so we
815 * can keep gpio_chips local to gpiolib.c, but the yield of
816 * gpio_lock prevents us from doing this.
818 spin_unlock_irqrestore(&gpio_lock, flags);
819 status = gpiochip_export(chip);
820 spin_lock_irqsave(&gpio_lock, flags);
822 spin_unlock_irqrestore(&gpio_lock, flags);
827 postcore_initcall(gpiolib_sysfs_init);