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 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 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 gpiochip_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 = gpiochip_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 DEVICE_ATTR(active_low, 0644,
357 gpio_active_low_show, gpio_active_low_store);
359 static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
362 struct device *dev = container_of(kobj, struct device, kobj);
363 struct gpio_desc *desc = dev_get_drvdata(dev);
364 umode_t mode = attr->mode;
365 bool show_direction = test_bit(FLAG_SYSFS_DIR, &desc->flags);
367 if (attr == &dev_attr_direction.attr) {
370 } else if (attr == &dev_attr_edge.attr) {
371 if (gpiod_to_irq(desc) < 0)
373 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
380 static struct attribute *gpio_attrs[] = {
381 &dev_attr_direction.attr,
383 &dev_attr_value.attr,
384 &dev_attr_active_low.attr,
388 static const struct attribute_group gpio_group = {
390 .is_visible = gpio_is_visible,
393 static const struct attribute_group *gpio_groups[] = {
399 * /sys/class/gpio/gpiochipN/
400 * /base ... matching gpio_chip.base (N)
401 * /label ... matching gpio_chip.label
402 * /ngpio ... matching gpio_chip.ngpio
405 static ssize_t chip_base_show(struct device *dev,
406 struct device_attribute *attr, char *buf)
408 const struct gpio_chip *chip = dev_get_drvdata(dev);
410 return sprintf(buf, "%d\n", chip->base);
412 static DEVICE_ATTR(base, 0444, chip_base_show, NULL);
414 static ssize_t chip_label_show(struct device *dev,
415 struct device_attribute *attr, char *buf)
417 const struct gpio_chip *chip = dev_get_drvdata(dev);
419 return sprintf(buf, "%s\n", chip->label ? : "");
421 static DEVICE_ATTR(label, 0444, chip_label_show, NULL);
423 static ssize_t chip_ngpio_show(struct device *dev,
424 struct device_attribute *attr, char *buf)
426 const struct gpio_chip *chip = dev_get_drvdata(dev);
428 return sprintf(buf, "%u\n", chip->ngpio);
430 static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL);
432 static struct attribute *gpiochip_attrs[] = {
434 &dev_attr_label.attr,
435 &dev_attr_ngpio.attr,
438 ATTRIBUTE_GROUPS(gpiochip);
441 * /sys/class/gpio/export ... write-only
442 * integer N ... number of GPIO to export (full access)
443 * /sys/class/gpio/unexport ... write-only
444 * integer N ... number of GPIO to unexport
446 static ssize_t export_store(struct class *class,
447 struct class_attribute *attr,
448 const char *buf, size_t len)
451 struct gpio_desc *desc;
454 status = kstrtol(buf, 0, &gpio);
458 desc = gpio_to_desc(gpio);
459 /* reject invalid GPIOs */
461 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
465 /* No extra locking here; FLAG_SYSFS just signifies that the
466 * request and export were done by on behalf of userspace, so
467 * they may be undone on its behalf too.
470 status = gpiod_request(desc, "sysfs");
472 if (status == -EPROBE_DEFER)
476 status = gpiod_export(desc, true);
480 set_bit(FLAG_SYSFS, &desc->flags);
484 pr_debug("%s: status %d\n", __func__, status);
485 return status ? : len;
488 static ssize_t unexport_store(struct class *class,
489 struct class_attribute *attr,
490 const char *buf, size_t len)
493 struct gpio_desc *desc;
496 status = kstrtol(buf, 0, &gpio);
500 desc = gpio_to_desc(gpio);
501 /* reject bogus commands (gpio_unexport ignores them) */
503 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
509 /* No extra locking here; FLAG_SYSFS just signifies that the
510 * request and export were done by on behalf of userspace, so
511 * they may be undone on its behalf too.
513 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
519 pr_debug("%s: status %d\n", __func__, status);
520 return status ? : len;
523 static struct class_attribute gpio_class_attrs[] = {
524 __ATTR(export, 0200, NULL, export_store),
525 __ATTR(unexport, 0200, NULL, unexport_store),
529 static struct class gpio_class = {
531 .owner = THIS_MODULE,
533 .class_attrs = gpio_class_attrs,
538 * gpiod_export - export a GPIO through sysfs
539 * @gpio: gpio to make available, already requested
540 * @direction_may_change: true if userspace may change gpio direction
541 * Context: arch_initcall or later
543 * When drivers want to make a GPIO accessible to userspace after they
544 * have requested it -- perhaps while debugging, or as part of their
545 * public interface -- they may use this routine. If the GPIO can
546 * change direction (some can't) and the caller allows it, userspace
547 * will see "direction" sysfs attribute which may be used to change
548 * the gpio's direction. A "value" attribute will always be provided.
550 * Returns zero on success, else an error.
552 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
554 struct gpio_chip *chip;
557 const char *ioname = NULL;
561 /* can't export until sysfs is available ... */
563 pr_debug("%s: called too early!\n", __func__);
568 pr_debug("%s: invalid gpio descriptor\n", __func__);
574 mutex_lock(&sysfs_lock);
576 /* check if chip is being removed */
577 if (!chip || !chip->exported) {
582 spin_lock_irqsave(&gpio_lock, flags);
583 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
584 test_bit(FLAG_EXPORT, &desc->flags)) {
585 spin_unlock_irqrestore(&gpio_lock, flags);
586 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
588 test_bit(FLAG_REQUESTED, &desc->flags),
589 test_bit(FLAG_EXPORT, &desc->flags));
594 if (desc->chip->direction_input && desc->chip->direction_output &&
595 direction_may_change) {
596 set_bit(FLAG_SYSFS_DIR, &desc->flags);
599 spin_unlock_irqrestore(&gpio_lock, flags);
601 offset = gpio_chip_hwgpio(desc);
602 if (desc->chip->names && desc->chip->names[offset])
603 ioname = desc->chip->names[offset];
605 dev = device_create_with_groups(&gpio_class, desc->chip->dev,
606 MKDEV(0, 0), desc, gpio_groups,
607 ioname ? ioname : "gpio%u",
610 status = PTR_ERR(dev);
614 set_bit(FLAG_EXPORT, &desc->flags);
615 mutex_unlock(&sysfs_lock);
619 mutex_unlock(&sysfs_lock);
620 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
623 EXPORT_SYMBOL_GPL(gpiod_export);
625 static int match_export(struct device *dev, const void *data)
627 return dev_get_drvdata(dev) == data;
631 * gpiod_export_link - create a sysfs link to an exported GPIO node
632 * @dev: device under which to create symlink
633 * @name: name of the symlink
634 * @gpio: gpio to create symlink to, already exported
636 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
637 * node. Caller is responsible for unlinking.
639 * Returns zero on success, else an error.
641 int gpiod_export_link(struct device *dev, const char *name,
642 struct gpio_desc *desc)
644 int status = -EINVAL;
647 pr_warn("%s: invalid GPIO\n", __func__);
651 mutex_lock(&sysfs_lock);
653 if (test_bit(FLAG_EXPORT, &desc->flags)) {
656 tdev = class_find_device(&gpio_class, NULL, desc, match_export);
658 status = sysfs_create_link(&dev->kobj, &tdev->kobj,
666 mutex_unlock(&sysfs_lock);
669 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
673 EXPORT_SYMBOL_GPL(gpiod_export_link);
676 * gpiod_sysfs_set_active_low - set the polarity of gpio sysfs value
677 * @gpio: gpio to change
678 * @value: non-zero to use active low, i.e. inverted values
680 * Set the polarity of /sys/class/gpio/gpioN/value sysfs attribute.
681 * The GPIO does not have to be exported yet. If poll(2) support has
682 * been enabled for either rising or falling edge, it will be
683 * reconfigured to follow the new polarity.
685 * Returns zero on success, else an error.
687 int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
689 struct device *dev = NULL;
690 int status = -EINVAL;
693 pr_warn("%s: invalid GPIO\n", __func__);
697 mutex_lock(&sysfs_lock);
699 if (test_bit(FLAG_EXPORT, &desc->flags)) {
700 dev = class_find_device(&gpio_class, NULL, desc, match_export);
707 status = sysfs_set_active_low(desc, dev, value);
710 mutex_unlock(&sysfs_lock);
713 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
717 EXPORT_SYMBOL_GPL(gpiod_sysfs_set_active_low);
720 * gpiod_unexport - reverse effect of gpio_export()
721 * @gpio: gpio to make unavailable
723 * This is implicit on gpio_free().
725 void gpiod_unexport(struct gpio_desc *desc)
728 struct device *dev = NULL;
731 pr_warn("%s: invalid GPIO\n", __func__);
735 mutex_lock(&sysfs_lock);
737 if (test_bit(FLAG_EXPORT, &desc->flags)) {
739 dev = class_find_device(&gpio_class, NULL, desc, match_export);
741 gpio_setup_irq(desc, dev, 0);
742 clear_bit(FLAG_SYSFS_DIR, &desc->flags);
743 clear_bit(FLAG_EXPORT, &desc->flags);
748 mutex_unlock(&sysfs_lock);
751 device_unregister(dev);
756 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
758 EXPORT_SYMBOL_GPL(gpiod_unexport);
760 int gpiochip_export(struct gpio_chip *chip)
765 /* Many systems register gpio chips for SOC support very early,
766 * before driver model support is available. In those cases we
767 * export this later, in gpiolib_sysfs_init() ... here we just
768 * verify that _some_ field of gpio_class got initialized.
773 /* use chip->base for the ID; it's already known to be unique */
774 mutex_lock(&sysfs_lock);
775 dev = device_create_with_groups(&gpio_class, chip->dev, MKDEV(0, 0),
776 chip, gpiochip_groups,
777 "gpiochip%d", chip->base);
779 status = PTR_ERR(dev);
782 chip->exported = (status == 0);
783 mutex_unlock(&sysfs_lock);
786 chip_dbg(chip, "%s: status %d\n", __func__, status);
791 void gpiochip_unexport(struct gpio_chip *chip)
795 struct gpio_desc *desc;
798 mutex_lock(&sysfs_lock);
799 dev = class_find_device(&gpio_class, NULL, chip, match_export);
802 device_unregister(dev);
803 /* prevent further gpiod exports */
804 chip->exported = false;
808 mutex_unlock(&sysfs_lock);
811 chip_dbg(chip, "%s: status %d\n", __func__, status);
813 /* unregister gpiod class devices owned by sysfs */
814 for (i = 0; i < chip->ngpio; i++) {
815 desc = &chip->desc[i];
816 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags))
821 static int __init gpiolib_sysfs_init(void)
825 struct gpio_chip *chip;
827 status = class_register(&gpio_class);
831 /* Scan and register the gpio_chips which registered very
832 * early (e.g. before the class_register above was called).
834 * We run before arch_initcall() so chip->dev nodes can have
835 * registered, and so arch_initcall() can always gpio_export().
837 spin_lock_irqsave(&gpio_lock, flags);
838 list_for_each_entry(chip, &gpio_chips, list) {
843 * TODO we yield gpio_lock here because gpiochip_export()
844 * acquires a mutex. This is unsafe and needs to be fixed.
846 * Also it would be nice to use gpiochip_find() here so we
847 * can keep gpio_chips local to gpiolib.c, but the yield of
848 * gpio_lock prevents us from doing this.
850 spin_unlock_irqrestore(&gpio_lock, flags);
851 status = gpiochip_export(chip);
852 spin_lock_irqsave(&gpio_lock, flags);
854 spin_unlock_irqrestore(&gpio_lock, flags);
859 postcore_initcall(gpiolib_sysfs_init);