1 // SPDX-License-Identifier: GPL-2.0
3 #include <linux/mutex.h>
4 #include <linux/device.h>
5 #include <linux/sysfs.h>
6 #include <linux/gpio/consumer.h>
7 #include <linux/gpio/driver.h>
8 #include <linux/interrupt.h>
9 #include <linux/kdev_t.h>
10 #include <linux/slab.h>
11 #include <linux/ctype.h>
15 #define GPIO_IRQF_TRIGGER_FALLING BIT(0)
16 #define GPIO_IRQF_TRIGGER_RISING BIT(1)
17 #define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \
18 GPIO_IRQF_TRIGGER_RISING)
21 struct gpio_desc *desc;
24 struct kernfs_node *value_kn;
26 unsigned char irq_flags;
28 bool direction_can_change;
32 * Lock to serialise gpiod export and unexport, and prevent re-export of
33 * gpiod whose chip is being unregistered.
35 static DEFINE_MUTEX(sysfs_lock);
38 * /sys/class/gpio/gpioN... only for GPIOs that are exported
40 * * MAY BE OMITTED if kernel won't allow direction changes
41 * * is read/write as "in" or "out"
42 * * may also be written as "high" or "low", initializing
43 * output value as specified ("out" implies "low")
45 * * always readable, subject to hardware behavior
46 * * may be writable, as zero/nonzero
48 * * configures behavior of poll(2) on /value
49 * * available only if pin can generate IRQs on input
50 * * is read/write as "none", "falling", "rising", or "both"
52 * * configures polarity of /value
53 * * is read/write as zero/nonzero
54 * * also affects existing and subsequent "falling" and "rising"
58 static ssize_t direction_show(struct device *dev,
59 struct device_attribute *attr, char *buf)
61 struct gpiod_data *data = dev_get_drvdata(dev);
62 struct gpio_desc *desc = data->desc;
65 mutex_lock(&data->mutex);
67 gpiod_get_direction(desc);
68 status = sprintf(buf, "%s\n",
69 test_bit(FLAG_IS_OUT, &desc->flags)
72 mutex_unlock(&data->mutex);
77 static ssize_t direction_store(struct device *dev,
78 struct device_attribute *attr, const char *buf, size_t size)
80 struct gpiod_data *data = dev_get_drvdata(dev);
81 struct gpio_desc *desc = data->desc;
84 mutex_lock(&data->mutex);
86 if (sysfs_streq(buf, "high"))
87 status = gpiod_direction_output_raw(desc, 1);
88 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
89 status = gpiod_direction_output_raw(desc, 0);
90 else if (sysfs_streq(buf, "in"))
91 status = gpiod_direction_input(desc);
95 mutex_unlock(&data->mutex);
97 return status ? : size;
99 static DEVICE_ATTR_RW(direction);
101 static ssize_t value_show(struct device *dev,
102 struct device_attribute *attr, char *buf)
104 struct gpiod_data *data = dev_get_drvdata(dev);
105 struct gpio_desc *desc = data->desc;
108 mutex_lock(&data->mutex);
110 status = gpiod_get_value_cansleep(desc);
114 buf[0] = '0' + status;
118 mutex_unlock(&data->mutex);
123 static ssize_t value_store(struct device *dev,
124 struct device_attribute *attr, const char *buf, size_t size)
126 struct gpiod_data *data = dev_get_drvdata(dev);
127 struct gpio_desc *desc = data->desc;
130 mutex_lock(&data->mutex);
132 if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
137 if (size <= 2 && isdigit(buf[0]) &&
138 (size == 1 || buf[1] == '\n'))
139 value = buf[0] - '0';
141 status = kstrtol(buf, 0, &value);
143 gpiod_set_value_cansleep(desc, value);
148 mutex_unlock(&data->mutex);
152 static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
154 static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
156 struct gpiod_data *data = priv;
158 sysfs_notify_dirent(data->value_kn);
163 /* Caller holds gpiod-data mutex. */
164 static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
166 struct gpiod_data *data = dev_get_drvdata(dev);
167 struct gpio_desc *desc = data->desc;
168 unsigned long irq_flags;
171 data->irq = gpiod_to_irq(desc);
175 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
179 irq_flags = IRQF_SHARED;
180 if (flags & GPIO_IRQF_TRIGGER_FALLING)
181 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
182 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
183 if (flags & GPIO_IRQF_TRIGGER_RISING)
184 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
185 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
188 * FIXME: This should be done in the irq_request_resources callback
189 * when the irq is requested, but a few drivers currently fail
192 * Remove this redundant call (along with the corresponding
193 * unlock) when those drivers have been fixed.
195 ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
199 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
204 data->irq_flags = flags;
209 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
211 sysfs_put(data->value_kn);
217 * Caller holds gpiod-data mutex (unless called after class-device
220 static void gpio_sysfs_free_irq(struct device *dev)
222 struct gpiod_data *data = dev_get_drvdata(dev);
223 struct gpio_desc *desc = data->desc;
226 free_irq(data->irq, data);
227 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
228 sysfs_put(data->value_kn);
231 static const struct {
234 } trigger_types[] = {
236 { "falling", GPIO_IRQF_TRIGGER_FALLING },
237 { "rising", GPIO_IRQF_TRIGGER_RISING },
238 { "both", GPIO_IRQF_TRIGGER_BOTH },
241 static ssize_t edge_show(struct device *dev,
242 struct device_attribute *attr, char *buf)
244 struct gpiod_data *data = dev_get_drvdata(dev);
248 mutex_lock(&data->mutex);
250 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
251 if (data->irq_flags == trigger_types[i].flags) {
252 status = sprintf(buf, "%s\n", trigger_types[i].name);
257 mutex_unlock(&data->mutex);
262 static ssize_t edge_store(struct device *dev,
263 struct device_attribute *attr, const char *buf, size_t size)
265 struct gpiod_data *data = dev_get_drvdata(dev);
267 ssize_t status = size;
270 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
271 if (sysfs_streq(trigger_types[i].name, buf))
275 if (i == ARRAY_SIZE(trigger_types))
278 flags = trigger_types[i].flags;
280 mutex_lock(&data->mutex);
282 if (flags == data->irq_flags) {
288 gpio_sysfs_free_irq(dev);
291 status = gpio_sysfs_request_irq(dev, flags);
297 mutex_unlock(&data->mutex);
301 static DEVICE_ATTR_RW(edge);
303 /* Caller holds gpiod-data mutex. */
304 static int gpio_sysfs_set_active_low(struct device *dev, int value)
306 struct gpiod_data *data = dev_get_drvdata(dev);
307 struct gpio_desc *desc = data->desc;
309 unsigned int flags = data->irq_flags;
311 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
315 set_bit(FLAG_ACTIVE_LOW, &desc->flags);
317 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
319 /* reconfigure poll(2) support if enabled on one edge only */
320 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
321 flags == GPIO_IRQF_TRIGGER_RISING) {
322 gpio_sysfs_free_irq(dev);
323 status = gpio_sysfs_request_irq(dev, flags);
329 static ssize_t active_low_show(struct device *dev,
330 struct device_attribute *attr, char *buf)
332 struct gpiod_data *data = dev_get_drvdata(dev);
333 struct gpio_desc *desc = data->desc;
336 mutex_lock(&data->mutex);
338 status = sprintf(buf, "%d\n",
339 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
341 mutex_unlock(&data->mutex);
346 static ssize_t active_low_store(struct device *dev,
347 struct device_attribute *attr, const char *buf, size_t size)
349 struct gpiod_data *data = dev_get_drvdata(dev);
353 mutex_lock(&data->mutex);
355 status = kstrtol(buf, 0, &value);
357 status = gpio_sysfs_set_active_low(dev, value);
359 mutex_unlock(&data->mutex);
361 return status ? : size;
363 static DEVICE_ATTR_RW(active_low);
365 static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
368 struct device *dev = container_of(kobj, struct device, kobj);
369 struct gpiod_data *data = dev_get_drvdata(dev);
370 struct gpio_desc *desc = data->desc;
371 umode_t mode = attr->mode;
372 bool show_direction = data->direction_can_change;
374 if (attr == &dev_attr_direction.attr) {
377 } else if (attr == &dev_attr_edge.attr) {
378 if (gpiod_to_irq(desc) < 0)
380 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
387 static struct attribute *gpio_attrs[] = {
388 &dev_attr_direction.attr,
390 &dev_attr_value.attr,
391 &dev_attr_active_low.attr,
395 static const struct attribute_group gpio_group = {
397 .is_visible = gpio_is_visible,
400 static const struct attribute_group *gpio_groups[] = {
406 * /sys/class/gpio/gpiochipN/
407 * /base ... matching gpio_chip.base (N)
408 * /label ... matching gpio_chip.label
409 * /ngpio ... matching gpio_chip.ngpio
412 static ssize_t base_show(struct device *dev,
413 struct device_attribute *attr, char *buf)
415 const struct gpio_chip *chip = dev_get_drvdata(dev);
417 return sprintf(buf, "%d\n", chip->base);
419 static DEVICE_ATTR_RO(base);
421 static ssize_t label_show(struct device *dev,
422 struct device_attribute *attr, char *buf)
424 const struct gpio_chip *chip = dev_get_drvdata(dev);
426 return sprintf(buf, "%s\n", chip->label ? : "");
428 static DEVICE_ATTR_RO(label);
430 static ssize_t ngpio_show(struct device *dev,
431 struct device_attribute *attr, char *buf)
433 const struct gpio_chip *chip = dev_get_drvdata(dev);
435 return sprintf(buf, "%u\n", chip->ngpio);
437 static DEVICE_ATTR_RO(ngpio);
439 static struct attribute *gpiochip_attrs[] = {
441 &dev_attr_label.attr,
442 &dev_attr_ngpio.attr,
445 ATTRIBUTE_GROUPS(gpiochip);
448 * /sys/class/gpio/export ... write-only
449 * integer N ... number of GPIO to export (full access)
450 * /sys/class/gpio/unexport ... write-only
451 * integer N ... number of GPIO to unexport
453 static ssize_t export_store(struct class *class,
454 struct class_attribute *attr,
455 const char *buf, size_t len)
458 struct gpio_desc *desc;
460 struct gpio_chip *gc;
463 status = kstrtol(buf, 0, &gpio);
467 desc = gpio_to_desc(gpio);
468 /* reject invalid GPIOs */
470 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
473 gc = desc->gdev->chip;
474 offset = gpio_chip_hwgpio(desc);
475 if (!gpiochip_line_is_valid(gc, offset)) {
476 pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
480 /* No extra locking here; FLAG_SYSFS just signifies that the
481 * request and export were done by on behalf of userspace, so
482 * they may be undone on its behalf too.
485 status = gpiod_request(desc, "sysfs");
487 if (status == -EPROBE_DEFER)
492 status = gpiod_set_transitory(desc, false);
494 status = gpiod_export(desc, true);
498 set_bit(FLAG_SYSFS, &desc->flags);
503 pr_debug("%s: status %d\n", __func__, status);
504 return status ? : len;
506 static CLASS_ATTR_WO(export);
508 static ssize_t unexport_store(struct class *class,
509 struct class_attribute *attr,
510 const char *buf, size_t len)
513 struct gpio_desc *desc;
516 status = kstrtol(buf, 0, &gpio);
520 desc = gpio_to_desc(gpio);
521 /* reject bogus commands (gpio_unexport ignores them) */
523 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
529 /* No extra locking here; FLAG_SYSFS just signifies that the
530 * request and export were done by on behalf of userspace, so
531 * they may be undone on its behalf too.
533 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
539 pr_debug("%s: status %d\n", __func__, status);
540 return status ? : len;
542 static CLASS_ATTR_WO(unexport);
544 static struct attribute *gpio_class_attrs[] = {
545 &class_attr_export.attr,
546 &class_attr_unexport.attr,
549 ATTRIBUTE_GROUPS(gpio_class);
551 static struct class gpio_class = {
553 .owner = THIS_MODULE,
555 .class_groups = gpio_class_groups,
560 * gpiod_export - export a GPIO through sysfs
561 * @desc: GPIO to make available, already requested
562 * @direction_may_change: true if userspace may change GPIO direction
563 * Context: arch_initcall or later
565 * When drivers want to make a GPIO accessible to userspace after they
566 * have requested it -- perhaps while debugging, or as part of their
567 * public interface -- they may use this routine. If the GPIO can
568 * change direction (some can't) and the caller allows it, userspace
569 * will see "direction" sysfs attribute which may be used to change
570 * the gpio's direction. A "value" attribute will always be provided.
572 * Returns zero on success, else an error.
574 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
576 struct gpio_chip *chip;
577 struct gpio_device *gdev;
578 struct gpiod_data *data;
581 const char *ioname = NULL;
585 /* can't export until sysfs is available ... */
587 pr_debug("%s: called too early!\n", __func__);
592 pr_debug("%s: invalid gpio descriptor\n", __func__);
599 mutex_lock(&sysfs_lock);
601 /* check if chip is being removed */
602 if (!chip || !gdev->mockdev) {
607 spin_lock_irqsave(&gpio_lock, flags);
608 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
609 test_bit(FLAG_EXPORT, &desc->flags)) {
610 spin_unlock_irqrestore(&gpio_lock, flags);
611 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
613 test_bit(FLAG_REQUESTED, &desc->flags),
614 test_bit(FLAG_EXPORT, &desc->flags));
618 spin_unlock_irqrestore(&gpio_lock, flags);
620 data = kzalloc(sizeof(*data), GFP_KERNEL);
627 mutex_init(&data->mutex);
628 if (chip->direction_input && chip->direction_output)
629 data->direction_can_change = direction_may_change;
631 data->direction_can_change = false;
633 offset = gpio_chip_hwgpio(desc);
634 if (chip->names && chip->names[offset])
635 ioname = chip->names[offset];
637 dev = device_create_with_groups(&gpio_class, &gdev->dev,
638 MKDEV(0, 0), data, gpio_groups,
639 ioname ? ioname : "gpio%u",
642 status = PTR_ERR(dev);
646 set_bit(FLAG_EXPORT, &desc->flags);
647 mutex_unlock(&sysfs_lock);
653 mutex_unlock(&sysfs_lock);
654 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
657 EXPORT_SYMBOL_GPL(gpiod_export);
659 static int match_export(struct device *dev, const void *desc)
661 struct gpiod_data *data = dev_get_drvdata(dev);
663 return data->desc == desc;
667 * gpiod_export_link - create a sysfs link to an exported GPIO node
668 * @dev: device under which to create symlink
669 * @name: name of the symlink
670 * @desc: GPIO to create symlink to, already exported
672 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
673 * node. Caller is responsible for unlinking.
675 * Returns zero on success, else an error.
677 int gpiod_export_link(struct device *dev, const char *name,
678 struct gpio_desc *desc)
684 pr_warn("%s: invalid GPIO\n", __func__);
688 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
692 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
697 EXPORT_SYMBOL_GPL(gpiod_export_link);
700 * gpiod_unexport - reverse effect of gpiod_export()
701 * @desc: GPIO to make unavailable
703 * This is implicit on gpiod_free().
705 void gpiod_unexport(struct gpio_desc *desc)
707 struct gpiod_data *data;
711 pr_warn("%s: invalid GPIO\n", __func__);
715 mutex_lock(&sysfs_lock);
717 if (!test_bit(FLAG_EXPORT, &desc->flags))
720 dev = class_find_device(&gpio_class, NULL, desc, match_export);
724 data = dev_get_drvdata(dev);
726 clear_bit(FLAG_EXPORT, &desc->flags);
728 device_unregister(dev);
731 * Release irq after deregistration to prevent race with edge_store.
734 gpio_sysfs_free_irq(dev);
736 mutex_unlock(&sysfs_lock);
744 mutex_unlock(&sysfs_lock);
746 EXPORT_SYMBOL_GPL(gpiod_unexport);
748 int gpiochip_sysfs_register(struct gpio_device *gdev)
751 struct device *parent;
752 struct gpio_chip *chip = gdev->chip;
755 * Many systems add gpio chips for SOC support very early,
756 * before driver model support is available. In those cases we
757 * register later, in gpiolib_sysfs_init() ... here we just
758 * verify that _some_ field of gpio_class got initialized.
764 * For sysfs backward compatibility we need to preserve this
765 * preferred parenting to the gpio_chip parent field, if set.
768 parent = chip->parent;
772 /* use chip->base for the ID; it's already known to be unique */
773 dev = device_create_with_groups(&gpio_class, parent,
775 chip, gpiochip_groups,
776 "gpiochip%d", chip->base);
780 mutex_lock(&sysfs_lock);
782 mutex_unlock(&sysfs_lock);
787 void gpiochip_sysfs_unregister(struct gpio_device *gdev)
789 struct gpio_desc *desc;
790 struct gpio_chip *chip = gdev->chip;
796 device_unregister(gdev->mockdev);
798 /* prevent further gpiod exports */
799 mutex_lock(&sysfs_lock);
800 gdev->mockdev = NULL;
801 mutex_unlock(&sysfs_lock);
803 /* unregister gpiod class devices owned by sysfs */
804 for (i = 0; i < chip->ngpio; i++) {
805 desc = &gdev->descs[i];
806 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags))
811 static int __init gpiolib_sysfs_init(void)
815 struct gpio_device *gdev;
817 status = class_register(&gpio_class);
821 /* Scan and register the gpio_chips which registered very
822 * early (e.g. before the class_register above was called).
824 * We run before arch_initcall() so chip->dev nodes can have
825 * registered, and so arch_initcall() can always gpio_export().
827 spin_lock_irqsave(&gpio_lock, flags);
828 list_for_each_entry(gdev, &gpio_devices, list) {
833 * TODO we yield gpio_lock here because
834 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
835 * and needs to be fixed.
837 * Also it would be nice to use gpiochip_find() here so we
838 * can keep gpio_chips local to gpiolib.c, but the yield of
839 * gpio_lock prevents us from doing this.
841 spin_unlock_irqrestore(&gpio_lock, flags);
842 status = gpiochip_sysfs_register(gdev);
843 spin_lock_irqsave(&gpio_lock, flags);
845 spin_unlock_irqrestore(&gpio_lock, flags);
849 postcore_initcall(gpiolib_sysfs_init);