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 = sprintf(buf, "%s\n",
70 test_bit(FLAG_IS_OUT, &desc->flags)
73 mutex_unlock(&data->mutex);
78 static ssize_t direction_store(struct device *dev,
79 struct device_attribute *attr, const char *buf, size_t size)
81 struct gpiod_data *data = dev_get_drvdata(dev);
82 struct gpio_desc *desc = data->desc;
85 mutex_lock(&data->mutex);
87 if (sysfs_streq(buf, "high"))
88 status = gpiod_direction_output_raw(desc, 1);
89 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
90 status = gpiod_direction_output_raw(desc, 0);
91 else if (sysfs_streq(buf, "in"))
92 status = gpiod_direction_input(desc);
96 mutex_unlock(&data->mutex);
98 return status ? : size;
100 static DEVICE_ATTR_RW(direction);
102 static ssize_t value_show(struct device *dev,
103 struct device_attribute *attr, char *buf)
105 struct gpiod_data *data = dev_get_drvdata(dev);
106 struct gpio_desc *desc = data->desc;
109 mutex_lock(&data->mutex);
111 status = gpiod_get_value_cansleep(desc);
115 buf[0] = '0' + status;
119 mutex_unlock(&data->mutex);
124 static ssize_t value_store(struct device *dev,
125 struct device_attribute *attr, const char *buf, size_t size)
127 struct gpiod_data *data = dev_get_drvdata(dev);
128 struct gpio_desc *desc = data->desc;
131 mutex_lock(&data->mutex);
133 if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
138 if (size <= 2 && isdigit(buf[0]) &&
139 (size == 1 || buf[1] == '\n'))
140 value = buf[0] - '0';
142 status = kstrtol(buf, 0, &value);
144 gpiod_set_value_cansleep(desc, value);
149 mutex_unlock(&data->mutex);
153 static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
155 static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
157 struct gpiod_data *data = priv;
159 sysfs_notify_dirent(data->value_kn);
164 /* Caller holds gpiod-data mutex. */
165 static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
167 struct gpiod_data *data = dev_get_drvdata(dev);
168 struct gpio_desc *desc = data->desc;
169 unsigned long irq_flags;
172 data->irq = gpiod_to_irq(desc);
176 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
180 irq_flags = IRQF_SHARED;
181 if (flags & GPIO_IRQF_TRIGGER_FALLING)
182 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
183 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
184 if (flags & GPIO_IRQF_TRIGGER_RISING)
185 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
186 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
189 * FIXME: This should be done in the irq_request_resources callback
190 * when the irq is requested, but a few drivers currently fail
193 * Remove this redundant call (along with the corresponding
194 * unlock) when those drivers have been fixed.
196 ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
200 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
205 data->irq_flags = flags;
210 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
212 sysfs_put(data->value_kn);
218 * Caller holds gpiod-data mutex (unless called after class-device
221 static void gpio_sysfs_free_irq(struct device *dev)
223 struct gpiod_data *data = dev_get_drvdata(dev);
224 struct gpio_desc *desc = data->desc;
227 free_irq(data->irq, data);
228 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
229 sysfs_put(data->value_kn);
232 static const struct {
235 } trigger_types[] = {
237 { "falling", GPIO_IRQF_TRIGGER_FALLING },
238 { "rising", GPIO_IRQF_TRIGGER_RISING },
239 { "both", GPIO_IRQF_TRIGGER_BOTH },
242 static ssize_t edge_show(struct device *dev,
243 struct device_attribute *attr, char *buf)
245 struct gpiod_data *data = dev_get_drvdata(dev);
249 mutex_lock(&data->mutex);
251 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
252 if (data->irq_flags == trigger_types[i].flags) {
253 status = sprintf(buf, "%s\n", trigger_types[i].name);
258 mutex_unlock(&data->mutex);
263 static ssize_t edge_store(struct device *dev,
264 struct device_attribute *attr, const char *buf, size_t size)
266 struct gpiod_data *data = dev_get_drvdata(dev);
268 ssize_t status = size;
271 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
272 if (sysfs_streq(trigger_types[i].name, buf))
276 if (i == ARRAY_SIZE(trigger_types))
279 flags = trigger_types[i].flags;
281 mutex_lock(&data->mutex);
283 if (flags == data->irq_flags) {
289 gpio_sysfs_free_irq(dev);
292 status = gpio_sysfs_request_irq(dev, flags);
298 mutex_unlock(&data->mutex);
302 static DEVICE_ATTR_RW(edge);
304 /* Caller holds gpiod-data mutex. */
305 static int gpio_sysfs_set_active_low(struct device *dev, int value)
307 struct gpiod_data *data = dev_get_drvdata(dev);
308 struct gpio_desc *desc = data->desc;
310 unsigned int flags = data->irq_flags;
312 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
316 set_bit(FLAG_ACTIVE_LOW, &desc->flags);
318 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
320 /* reconfigure poll(2) support if enabled on one edge only */
321 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
322 flags == GPIO_IRQF_TRIGGER_RISING) {
323 gpio_sysfs_free_irq(dev);
324 status = gpio_sysfs_request_irq(dev, flags);
330 static ssize_t active_low_show(struct device *dev,
331 struct device_attribute *attr, char *buf)
333 struct gpiod_data *data = dev_get_drvdata(dev);
334 struct gpio_desc *desc = data->desc;
337 mutex_lock(&data->mutex);
339 status = sprintf(buf, "%d\n",
340 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
342 mutex_unlock(&data->mutex);
347 static ssize_t active_low_store(struct device *dev,
348 struct device_attribute *attr, const char *buf, size_t size)
350 struct gpiod_data *data = dev_get_drvdata(dev);
354 mutex_lock(&data->mutex);
356 status = kstrtol(buf, 0, &value);
358 status = gpio_sysfs_set_active_low(dev, value);
360 mutex_unlock(&data->mutex);
362 return status ? : size;
364 static DEVICE_ATTR_RW(active_low);
366 static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
369 struct device *dev = kobj_to_dev(kobj);
370 struct gpiod_data *data = dev_get_drvdata(dev);
371 struct gpio_desc *desc = data->desc;
372 umode_t mode = attr->mode;
373 bool show_direction = data->direction_can_change;
375 if (attr == &dev_attr_direction.attr) {
378 } else if (attr == &dev_attr_edge.attr) {
379 if (gpiod_to_irq(desc) < 0)
381 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
388 static struct attribute *gpio_attrs[] = {
389 &dev_attr_direction.attr,
391 &dev_attr_value.attr,
392 &dev_attr_active_low.attr,
396 static const struct attribute_group gpio_group = {
398 .is_visible = gpio_is_visible,
401 static const struct attribute_group *gpio_groups[] = {
407 * /sys/class/gpio/gpiochipN/
408 * /base ... matching gpio_chip.base (N)
409 * /label ... matching gpio_chip.label
410 * /ngpio ... matching gpio_chip.ngpio
413 static ssize_t base_show(struct device *dev,
414 struct device_attribute *attr, char *buf)
416 const struct gpio_chip *chip = dev_get_drvdata(dev);
418 return sprintf(buf, "%d\n", chip->base);
420 static DEVICE_ATTR_RO(base);
422 static ssize_t label_show(struct device *dev,
423 struct device_attribute *attr, char *buf)
425 const struct gpio_chip *chip = dev_get_drvdata(dev);
427 return sprintf(buf, "%s\n", chip->label ? : "");
429 static DEVICE_ATTR_RO(label);
431 static ssize_t ngpio_show(struct device *dev,
432 struct device_attribute *attr, char *buf)
434 const struct gpio_chip *chip = dev_get_drvdata(dev);
436 return sprintf(buf, "%u\n", chip->ngpio);
438 static DEVICE_ATTR_RO(ngpio);
440 static struct attribute *gpiochip_attrs[] = {
442 &dev_attr_label.attr,
443 &dev_attr_ngpio.attr,
446 ATTRIBUTE_GROUPS(gpiochip);
449 * /sys/class/gpio/export ... write-only
450 * integer N ... number of GPIO to export (full access)
451 * /sys/class/gpio/unexport ... write-only
452 * integer N ... number of GPIO to unexport
454 static ssize_t export_store(struct class *class,
455 struct class_attribute *attr,
456 const char *buf, size_t len)
459 struct gpio_desc *desc;
461 struct gpio_chip *gc;
464 status = kstrtol(buf, 0, &gpio);
468 desc = gpio_to_desc(gpio);
469 /* reject invalid GPIOs */
471 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
474 gc = desc->gdev->chip;
475 offset = gpio_chip_hwgpio(desc);
476 if (!gpiochip_line_is_valid(gc, offset)) {
477 pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
481 /* No extra locking here; FLAG_SYSFS just signifies that the
482 * request and export were done by on behalf of userspace, so
483 * they may be undone on its behalf too.
486 status = gpiod_request(desc, "sysfs");
488 if (status == -EPROBE_DEFER)
493 status = gpiod_set_transitory(desc, false);
499 status = gpiod_export(desc, true);
503 set_bit(FLAG_SYSFS, &desc->flags);
507 pr_debug("%s: status %d\n", __func__, status);
508 return status ? : len;
510 static CLASS_ATTR_WO(export);
512 static ssize_t unexport_store(struct class *class,
513 struct class_attribute *attr,
514 const char *buf, size_t len)
517 struct gpio_desc *desc;
520 status = kstrtol(buf, 0, &gpio);
524 desc = gpio_to_desc(gpio);
525 /* reject bogus commands (gpio_unexport ignores them) */
527 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
533 /* No extra locking here; FLAG_SYSFS just signifies that the
534 * request and export were done by on behalf of userspace, so
535 * they may be undone on its behalf too.
537 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
543 pr_debug("%s: status %d\n", __func__, status);
544 return status ? : len;
546 static CLASS_ATTR_WO(unexport);
548 static struct attribute *gpio_class_attrs[] = {
549 &class_attr_export.attr,
550 &class_attr_unexport.attr,
553 ATTRIBUTE_GROUPS(gpio_class);
555 static struct class gpio_class = {
557 .owner = THIS_MODULE,
559 .class_groups = gpio_class_groups,
564 * gpiod_export - export a GPIO through sysfs
565 * @desc: GPIO to make available, already requested
566 * @direction_may_change: true if userspace may change GPIO direction
567 * Context: arch_initcall or later
569 * When drivers want to make a GPIO accessible to userspace after they
570 * have requested it -- perhaps while debugging, or as part of their
571 * public interface -- they may use this routine. If the GPIO can
572 * change direction (some can't) and the caller allows it, userspace
573 * will see "direction" sysfs attribute which may be used to change
574 * the gpio's direction. A "value" attribute will always be provided.
576 * Returns zero on success, else an error.
578 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
580 struct gpio_chip *chip;
581 struct gpio_device *gdev;
582 struct gpiod_data *data;
585 const char *ioname = NULL;
589 /* can't export until sysfs is available ... */
591 pr_debug("%s: called too early!\n", __func__);
596 pr_debug("%s: invalid gpio descriptor\n", __func__);
603 mutex_lock(&sysfs_lock);
605 /* check if chip is being removed */
606 if (!chip || !gdev->mockdev) {
611 spin_lock_irqsave(&gpio_lock, flags);
612 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
613 test_bit(FLAG_EXPORT, &desc->flags)) {
614 spin_unlock_irqrestore(&gpio_lock, flags);
615 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
617 test_bit(FLAG_REQUESTED, &desc->flags),
618 test_bit(FLAG_EXPORT, &desc->flags));
622 spin_unlock_irqrestore(&gpio_lock, flags);
624 data = kzalloc(sizeof(*data), GFP_KERNEL);
631 mutex_init(&data->mutex);
632 if (chip->direction_input && chip->direction_output)
633 data->direction_can_change = direction_may_change;
635 data->direction_can_change = false;
637 offset = gpio_chip_hwgpio(desc);
638 if (chip->names && chip->names[offset])
639 ioname = chip->names[offset];
641 dev = device_create_with_groups(&gpio_class, &gdev->dev,
642 MKDEV(0, 0), data, gpio_groups,
643 ioname ? ioname : "gpio%u",
646 status = PTR_ERR(dev);
650 set_bit(FLAG_EXPORT, &desc->flags);
651 mutex_unlock(&sysfs_lock);
657 mutex_unlock(&sysfs_lock);
658 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
661 EXPORT_SYMBOL_GPL(gpiod_export);
663 static int match_export(struct device *dev, const void *desc)
665 struct gpiod_data *data = dev_get_drvdata(dev);
667 return data->desc == desc;
671 * gpiod_export_link - create a sysfs link to an exported GPIO node
672 * @dev: device under which to create symlink
673 * @name: name of the symlink
674 * @desc: GPIO to create symlink to, already exported
676 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
677 * node. Caller is responsible for unlinking.
679 * Returns zero on success, else an error.
681 int gpiod_export_link(struct device *dev, const char *name,
682 struct gpio_desc *desc)
688 pr_warn("%s: invalid GPIO\n", __func__);
692 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
696 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
701 EXPORT_SYMBOL_GPL(gpiod_export_link);
704 * gpiod_unexport - reverse effect of gpiod_export()
705 * @desc: GPIO to make unavailable
707 * This is implicit on gpiod_free().
709 void gpiod_unexport(struct gpio_desc *desc)
711 struct gpiod_data *data;
715 pr_warn("%s: invalid GPIO\n", __func__);
719 mutex_lock(&sysfs_lock);
721 if (!test_bit(FLAG_EXPORT, &desc->flags))
724 dev = class_find_device(&gpio_class, NULL, desc, match_export);
728 data = dev_get_drvdata(dev);
730 clear_bit(FLAG_EXPORT, &desc->flags);
732 device_unregister(dev);
735 * Release irq after deregistration to prevent race with edge_store.
738 gpio_sysfs_free_irq(dev);
740 mutex_unlock(&sysfs_lock);
748 mutex_unlock(&sysfs_lock);
750 EXPORT_SYMBOL_GPL(gpiod_unexport);
752 int gpiochip_sysfs_register(struct gpio_device *gdev)
755 struct device *parent;
756 struct gpio_chip *chip = gdev->chip;
759 * Many systems add gpio chips for SOC support very early,
760 * before driver model support is available. In those cases we
761 * register later, in gpiolib_sysfs_init() ... here we just
762 * verify that _some_ field of gpio_class got initialized.
768 * For sysfs backward compatibility we need to preserve this
769 * preferred parenting to the gpio_chip parent field, if set.
772 parent = chip->parent;
776 /* use chip->base for the ID; it's already known to be unique */
777 dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), chip,
778 gpiochip_groups, GPIOCHIP_NAME "%d",
783 mutex_lock(&sysfs_lock);
785 mutex_unlock(&sysfs_lock);
790 void gpiochip_sysfs_unregister(struct gpio_device *gdev)
792 struct gpio_desc *desc;
793 struct gpio_chip *chip = gdev->chip;
799 device_unregister(gdev->mockdev);
801 /* prevent further gpiod exports */
802 mutex_lock(&sysfs_lock);
803 gdev->mockdev = NULL;
804 mutex_unlock(&sysfs_lock);
806 /* unregister gpiod class devices owned by sysfs */
807 for (i = 0; i < chip->ngpio; i++) {
808 desc = &gdev->descs[i];
809 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags))
814 static int __init gpiolib_sysfs_init(void)
818 struct gpio_device *gdev;
820 status = class_register(&gpio_class);
824 /* Scan and register the gpio_chips which registered very
825 * early (e.g. before the class_register above was called).
827 * We run before arch_initcall() so chip->dev nodes can have
828 * registered, and so arch_initcall() can always gpio_export().
830 spin_lock_irqsave(&gpio_lock, flags);
831 list_for_each_entry(gdev, &gpio_devices, list) {
836 * TODO we yield gpio_lock here because
837 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
838 * and needs to be fixed.
840 * Also it would be nice to use gpiochip_find() here so we
841 * can keep gpio_chips local to gpiolib.c, but the yield of
842 * gpio_lock prevents us from doing this.
844 spin_unlock_irqrestore(&gpio_lock, flags);
845 status = gpiochip_sysfs_register(gdev);
846 spin_lock_irqsave(&gpio_lock, flags);
848 spin_unlock_irqrestore(&gpio_lock, flags);
852 postcore_initcall(gpiolib_sysfs_init);