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>
14 #include "gpiolib-sysfs.h"
16 #define GPIO_IRQF_TRIGGER_FALLING BIT(0)
17 #define GPIO_IRQF_TRIGGER_RISING BIT(1)
18 #define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \
19 GPIO_IRQF_TRIGGER_RISING)
22 struct gpio_desc *desc;
25 struct kernfs_node *value_kn;
27 unsigned char irq_flags;
29 bool direction_can_change;
33 * Lock to serialise gpiod export and unexport, and prevent re-export of
34 * gpiod whose chip is being unregistered.
36 static DEFINE_MUTEX(sysfs_lock);
39 * /sys/class/gpio/gpioN... only for GPIOs that are exported
41 * * MAY BE OMITTED if kernel won't allow direction changes
42 * * is read/write as "in" or "out"
43 * * may also be written as "high" or "low", initializing
44 * output value as specified ("out" implies "low")
46 * * always readable, subject to hardware behavior
47 * * may be writable, as zero/nonzero
49 * * configures behavior of poll(2) on /value
50 * * available only if pin can generate IRQs on input
51 * * is read/write as "none", "falling", "rising", or "both"
53 * * configures polarity of /value
54 * * is read/write as zero/nonzero
55 * * also affects existing and subsequent "falling" and "rising"
59 static ssize_t direction_show(struct device *dev,
60 struct device_attribute *attr, char *buf)
62 struct gpiod_data *data = dev_get_drvdata(dev);
63 struct gpio_desc *desc = data->desc;
66 mutex_lock(&data->mutex);
68 gpiod_get_direction(desc);
69 status = sysfs_emit(buf, "%s\n",
70 test_bit(FLAG_IS_OUT, &desc->flags) ? "out" : "in");
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);
112 status = sysfs_emit(buf, "%zd\n", status);
114 mutex_unlock(&data->mutex);
119 static ssize_t value_store(struct device *dev,
120 struct device_attribute *attr, const char *buf, size_t size)
122 struct gpiod_data *data = dev_get_drvdata(dev);
123 struct gpio_desc *desc = data->desc;
126 mutex_lock(&data->mutex);
128 if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
133 if (size <= 2 && isdigit(buf[0]) &&
134 (size == 1 || buf[1] == '\n'))
135 value = buf[0] - '0';
137 status = kstrtol(buf, 0, &value);
139 gpiod_set_value_cansleep(desc, value);
144 mutex_unlock(&data->mutex);
148 static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
150 static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
152 struct gpiod_data *data = priv;
154 sysfs_notify_dirent(data->value_kn);
159 /* Caller holds gpiod-data mutex. */
160 static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
162 struct gpiod_data *data = dev_get_drvdata(dev);
163 struct gpio_desc *desc = data->desc;
164 unsigned long irq_flags;
167 data->irq = gpiod_to_irq(desc);
171 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
175 irq_flags = IRQF_SHARED;
176 if (flags & GPIO_IRQF_TRIGGER_FALLING)
177 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
178 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
179 if (flags & GPIO_IRQF_TRIGGER_RISING)
180 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
181 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
184 * FIXME: This should be done in the irq_request_resources callback
185 * when the irq is requested, but a few drivers currently fail
188 * Remove this redundant call (along with the corresponding
189 * unlock) when those drivers have been fixed.
191 ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
195 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
200 data->irq_flags = flags;
205 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
207 sysfs_put(data->value_kn);
213 * Caller holds gpiod-data mutex (unless called after class-device
216 static void gpio_sysfs_free_irq(struct device *dev)
218 struct gpiod_data *data = dev_get_drvdata(dev);
219 struct gpio_desc *desc = data->desc;
222 free_irq(data->irq, data);
223 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
224 sysfs_put(data->value_kn);
227 static const struct {
230 } trigger_types[] = {
232 { "falling", GPIO_IRQF_TRIGGER_FALLING },
233 { "rising", GPIO_IRQF_TRIGGER_RISING },
234 { "both", GPIO_IRQF_TRIGGER_BOTH },
237 static ssize_t edge_show(struct device *dev,
238 struct device_attribute *attr, char *buf)
240 struct gpiod_data *data = dev_get_drvdata(dev);
244 mutex_lock(&data->mutex);
246 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
247 if (data->irq_flags == trigger_types[i].flags)
250 if (i < ARRAY_SIZE(trigger_types))
251 status = sysfs_emit(buf, "%s\n", trigger_types[i].name);
253 mutex_unlock(&data->mutex);
258 static ssize_t edge_store(struct device *dev,
259 struct device_attribute *attr, const char *buf, size_t size)
261 struct gpiod_data *data = dev_get_drvdata(dev);
263 ssize_t status = size;
266 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
267 if (sysfs_streq(trigger_types[i].name, buf))
271 if (i == ARRAY_SIZE(trigger_types))
274 flags = trigger_types[i].flags;
276 mutex_lock(&data->mutex);
278 if (flags == data->irq_flags) {
284 gpio_sysfs_free_irq(dev);
287 status = gpio_sysfs_request_irq(dev, flags);
293 mutex_unlock(&data->mutex);
297 static DEVICE_ATTR_RW(edge);
299 /* Caller holds gpiod-data mutex. */
300 static int gpio_sysfs_set_active_low(struct device *dev, int value)
302 struct gpiod_data *data = dev_get_drvdata(dev);
303 struct gpio_desc *desc = data->desc;
305 unsigned int flags = data->irq_flags;
307 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
310 assign_bit(FLAG_ACTIVE_LOW, &desc->flags, value);
312 /* reconfigure poll(2) support if enabled on one edge only */
313 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
314 flags == GPIO_IRQF_TRIGGER_RISING) {
315 gpio_sysfs_free_irq(dev);
316 status = gpio_sysfs_request_irq(dev, flags);
322 static ssize_t active_low_show(struct device *dev,
323 struct device_attribute *attr, char *buf)
325 struct gpiod_data *data = dev_get_drvdata(dev);
326 struct gpio_desc *desc = data->desc;
329 mutex_lock(&data->mutex);
331 status = sysfs_emit(buf, "%d\n",
332 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
334 mutex_unlock(&data->mutex);
339 static ssize_t active_low_store(struct device *dev,
340 struct device_attribute *attr, const char *buf, size_t size)
342 struct gpiod_data *data = dev_get_drvdata(dev);
346 mutex_lock(&data->mutex);
348 status = kstrtol(buf, 0, &value);
350 status = gpio_sysfs_set_active_low(dev, value);
352 mutex_unlock(&data->mutex);
354 return status ? : size;
356 static DEVICE_ATTR_RW(active_low);
358 static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
361 struct device *dev = kobj_to_dev(kobj);
362 struct gpiod_data *data = dev_get_drvdata(dev);
363 struct gpio_desc *desc = data->desc;
364 umode_t mode = attr->mode;
365 bool show_direction = data->direction_can_change;
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 base_show(struct device *dev,
406 struct device_attribute *attr, char *buf)
408 const struct gpio_chip *chip = dev_get_drvdata(dev);
410 return sysfs_emit(buf, "%d\n", chip->base);
412 static DEVICE_ATTR_RO(base);
414 static ssize_t label_show(struct device *dev,
415 struct device_attribute *attr, char *buf)
417 const struct gpio_chip *chip = dev_get_drvdata(dev);
419 return sysfs_emit(buf, "%s\n", chip->label ?: "");
421 static DEVICE_ATTR_RO(label);
423 static ssize_t ngpio_show(struct device *dev,
424 struct device_attribute *attr, char *buf)
426 const struct gpio_chip *chip = dev_get_drvdata(dev);
428 return sysfs_emit(buf, "%u\n", chip->ngpio);
430 static DEVICE_ATTR_RO(ngpio);
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;
453 struct gpio_chip *gc;
456 status = kstrtol(buf, 0, &gpio);
460 desc = gpio_to_desc(gpio);
461 /* reject invalid GPIOs */
463 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
466 gc = desc->gdev->chip;
467 offset = gpio_chip_hwgpio(desc);
468 if (!gpiochip_line_is_valid(gc, offset)) {
469 pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
473 /* No extra locking here; FLAG_SYSFS just signifies that the
474 * request and export were done by on behalf of userspace, so
475 * they may be undone on its behalf too.
478 status = gpiod_request_user(desc, "sysfs");
482 status = gpiod_set_transitory(desc, false);
484 status = gpiod_export(desc, true);
488 set_bit(FLAG_SYSFS, &desc->flags);
493 pr_debug("%s: status %d\n", __func__, status);
494 return status ? : len;
496 static CLASS_ATTR_WO(export);
498 static ssize_t unexport_store(struct class *class,
499 struct class_attribute *attr,
500 const char *buf, size_t len)
503 struct gpio_desc *desc;
506 status = kstrtol(buf, 0, &gpio);
510 desc = gpio_to_desc(gpio);
511 /* reject bogus commands (gpio_unexport ignores them) */
513 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
519 /* No extra locking here; FLAG_SYSFS just signifies that the
520 * request and export were done by on behalf of userspace, so
521 * they may be undone on its behalf too.
523 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
529 pr_debug("%s: status %d\n", __func__, status);
530 return status ? : len;
532 static CLASS_ATTR_WO(unexport);
534 static struct attribute *gpio_class_attrs[] = {
535 &class_attr_export.attr,
536 &class_attr_unexport.attr,
539 ATTRIBUTE_GROUPS(gpio_class);
541 static struct class gpio_class = {
543 .owner = THIS_MODULE,
545 .class_groups = gpio_class_groups,
550 * gpiod_export - export a GPIO through sysfs
551 * @desc: GPIO to make available, already requested
552 * @direction_may_change: true if userspace may change GPIO direction
553 * Context: arch_initcall or later
555 * When drivers want to make a GPIO accessible to userspace after they
556 * have requested it -- perhaps while debugging, or as part of their
557 * public interface -- they may use this routine. If the GPIO can
558 * change direction (some can't) and the caller allows it, userspace
559 * will see "direction" sysfs attribute which may be used to change
560 * the gpio's direction. A "value" attribute will always be provided.
562 * Returns zero on success, else an error.
564 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
566 struct gpio_chip *chip;
567 struct gpio_device *gdev;
568 struct gpiod_data *data;
571 const char *ioname = NULL;
575 /* can't export until sysfs is available ... */
577 pr_debug("%s: called too early!\n", __func__);
582 pr_debug("%s: invalid gpio descriptor\n", __func__);
589 mutex_lock(&sysfs_lock);
591 /* check if chip is being removed */
592 if (!chip || !gdev->mockdev) {
597 spin_lock_irqsave(&gpio_lock, flags);
598 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
599 test_bit(FLAG_EXPORT, &desc->flags)) {
600 spin_unlock_irqrestore(&gpio_lock, flags);
601 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
603 test_bit(FLAG_REQUESTED, &desc->flags),
604 test_bit(FLAG_EXPORT, &desc->flags));
608 spin_unlock_irqrestore(&gpio_lock, flags);
610 data = kzalloc(sizeof(*data), GFP_KERNEL);
617 mutex_init(&data->mutex);
618 if (chip->direction_input && chip->direction_output)
619 data->direction_can_change = direction_may_change;
621 data->direction_can_change = false;
623 offset = gpio_chip_hwgpio(desc);
624 if (chip->names && chip->names[offset])
625 ioname = chip->names[offset];
627 dev = device_create_with_groups(&gpio_class, &gdev->dev,
628 MKDEV(0, 0), data, gpio_groups,
629 ioname ? ioname : "gpio%u",
632 status = PTR_ERR(dev);
636 set_bit(FLAG_EXPORT, &desc->flags);
637 mutex_unlock(&sysfs_lock);
643 mutex_unlock(&sysfs_lock);
644 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
647 EXPORT_SYMBOL_GPL(gpiod_export);
649 static int match_export(struct device *dev, const void *desc)
651 struct gpiod_data *data = dev_get_drvdata(dev);
653 return data->desc == desc;
657 * gpiod_export_link - create a sysfs link to an exported GPIO node
658 * @dev: device under which to create symlink
659 * @name: name of the symlink
660 * @desc: GPIO to create symlink to, already exported
662 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
663 * node. Caller is responsible for unlinking.
665 * Returns zero on success, else an error.
667 int gpiod_export_link(struct device *dev, const char *name,
668 struct gpio_desc *desc)
674 pr_warn("%s: invalid GPIO\n", __func__);
678 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
682 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
687 EXPORT_SYMBOL_GPL(gpiod_export_link);
690 * gpiod_unexport - reverse effect of gpiod_export()
691 * @desc: GPIO to make unavailable
693 * This is implicit on gpiod_free().
695 void gpiod_unexport(struct gpio_desc *desc)
697 struct gpiod_data *data;
701 pr_warn("%s: invalid GPIO\n", __func__);
705 mutex_lock(&sysfs_lock);
707 if (!test_bit(FLAG_EXPORT, &desc->flags))
710 dev = class_find_device(&gpio_class, NULL, desc, match_export);
714 data = dev_get_drvdata(dev);
716 clear_bit(FLAG_EXPORT, &desc->flags);
718 device_unregister(dev);
721 * Release irq after deregistration to prevent race with edge_store.
724 gpio_sysfs_free_irq(dev);
726 mutex_unlock(&sysfs_lock);
734 mutex_unlock(&sysfs_lock);
736 EXPORT_SYMBOL_GPL(gpiod_unexport);
738 int gpiochip_sysfs_register(struct gpio_device *gdev)
741 struct device *parent;
742 struct gpio_chip *chip = gdev->chip;
745 * Many systems add gpio chips for SOC support very early,
746 * before driver model support is available. In those cases we
747 * register later, in gpiolib_sysfs_init() ... here we just
748 * verify that _some_ field of gpio_class got initialized.
754 * For sysfs backward compatibility we need to preserve this
755 * preferred parenting to the gpio_chip parent field, if set.
758 parent = chip->parent;
762 /* use chip->base for the ID; it's already known to be unique */
763 dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), chip,
764 gpiochip_groups, GPIOCHIP_NAME "%d",
769 mutex_lock(&sysfs_lock);
771 mutex_unlock(&sysfs_lock);
776 void gpiochip_sysfs_unregister(struct gpio_device *gdev)
778 struct gpio_desc *desc;
779 struct gpio_chip *chip = gdev->chip;
785 device_unregister(gdev->mockdev);
787 /* prevent further gpiod exports */
788 mutex_lock(&sysfs_lock);
789 gdev->mockdev = NULL;
790 mutex_unlock(&sysfs_lock);
792 /* unregister gpiod class devices owned by sysfs */
793 for (i = 0; i < chip->ngpio; i++) {
794 desc = &gdev->descs[i];
795 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags))
800 static int __init gpiolib_sysfs_init(void)
804 struct gpio_device *gdev;
806 status = class_register(&gpio_class);
810 /* Scan and register the gpio_chips which registered very
811 * early (e.g. before the class_register above was called).
813 * We run before arch_initcall() so chip->dev nodes can have
814 * registered, and so arch_initcall() can always gpio_export().
816 spin_lock_irqsave(&gpio_lock, flags);
817 list_for_each_entry(gdev, &gpio_devices, list) {
822 * TODO we yield gpio_lock here because
823 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
824 * and needs to be fixed.
826 * Also it would be nice to use gpiochip_find() here so we
827 * can keep gpio_chips local to gpiolib.c, but the yield of
828 * gpio_lock prevents us from doing this.
830 spin_unlock_irqrestore(&gpio_lock, flags);
831 status = gpiochip_sysfs_register(gdev);
832 spin_lock_irqsave(&gpio_lock, flags);
834 spin_unlock_irqrestore(&gpio_lock, flags);
838 postcore_initcall(gpiolib_sysfs_init);