1 // SPDX-License-Identifier: GPL-2.0
3 #include <linux/bitops.h>
4 #include <linux/device.h>
6 #include <linux/init.h>
7 #include <linux/interrupt.h>
8 #include <linux/kdev_t.h>
9 #include <linux/kstrtox.h>
10 #include <linux/list.h>
11 #include <linux/mutex.h>
12 #include <linux/printk.h>
13 #include <linux/slab.h>
14 #include <linux/spinlock.h>
15 #include <linux/string.h>
16 #include <linux/sysfs.h>
17 #include <linux/types.h>
19 #include <linux/gpio/consumer.h>
20 #include <linux/gpio/driver.h>
23 #include "gpiolib-sysfs.h"
27 #define GPIO_IRQF_TRIGGER_NONE 0
28 #define GPIO_IRQF_TRIGGER_FALLING BIT(0)
29 #define GPIO_IRQF_TRIGGER_RISING BIT(1)
30 #define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \
31 GPIO_IRQF_TRIGGER_RISING)
34 struct gpio_desc *desc;
37 struct kernfs_node *value_kn;
39 unsigned char irq_flags;
41 bool direction_can_change;
45 * Lock to serialise gpiod export and unexport, and prevent re-export of
46 * gpiod whose chip is being unregistered.
48 static DEFINE_MUTEX(sysfs_lock);
51 * /sys/class/gpio/gpioN... only for GPIOs that are exported
53 * * MAY BE OMITTED if kernel won't allow direction changes
54 * * is read/write as "in" or "out"
55 * * may also be written as "high" or "low", initializing
56 * output value as specified ("out" implies "low")
58 * * always readable, subject to hardware behavior
59 * * may be writable, as zero/nonzero
61 * * configures behavior of poll(2) on /value
62 * * available only if pin can generate IRQs on input
63 * * is read/write as "none", "falling", "rising", or "both"
65 * * configures polarity of /value
66 * * is read/write as zero/nonzero
67 * * also affects existing and subsequent "falling" and "rising"
71 static ssize_t direction_show(struct device *dev,
72 struct device_attribute *attr, char *buf)
74 struct gpiod_data *data = dev_get_drvdata(dev);
75 struct gpio_desc *desc = data->desc;
78 mutex_lock(&data->mutex);
80 gpiod_get_direction(desc);
81 value = !!test_bit(FLAG_IS_OUT, &desc->flags);
83 mutex_unlock(&data->mutex);
85 return sysfs_emit(buf, "%s\n", value ? "out" : "in");
88 static ssize_t direction_store(struct device *dev,
89 struct device_attribute *attr, const char *buf, size_t size)
91 struct gpiod_data *data = dev_get_drvdata(dev);
92 struct gpio_desc *desc = data->desc;
95 mutex_lock(&data->mutex);
97 if (sysfs_streq(buf, "high"))
98 status = gpiod_direction_output_raw(desc, 1);
99 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
100 status = gpiod_direction_output_raw(desc, 0);
101 else if (sysfs_streq(buf, "in"))
102 status = gpiod_direction_input(desc);
106 mutex_unlock(&data->mutex);
108 return status ? : size;
110 static DEVICE_ATTR_RW(direction);
112 static ssize_t value_show(struct device *dev,
113 struct device_attribute *attr, char *buf)
115 struct gpiod_data *data = dev_get_drvdata(dev);
116 struct gpio_desc *desc = data->desc;
119 mutex_lock(&data->mutex);
121 status = gpiod_get_value_cansleep(desc);
123 mutex_unlock(&data->mutex);
128 return sysfs_emit(buf, "%zd\n", status);
131 static ssize_t value_store(struct device *dev,
132 struct device_attribute *attr, const char *buf, size_t size)
134 struct gpiod_data *data = dev_get_drvdata(dev);
135 struct gpio_desc *desc = data->desc;
139 status = kstrtol(buf, 0, &value);
141 mutex_lock(&data->mutex);
143 if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
145 } else if (status == 0) {
146 gpiod_set_value_cansleep(desc, value);
150 mutex_unlock(&data->mutex);
154 static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
156 static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
158 struct gpiod_data *data = priv;
160 sysfs_notify_dirent(data->value_kn);
165 /* Caller holds gpiod-data mutex. */
166 static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
168 struct gpiod_data *data = dev_get_drvdata(dev);
169 struct gpio_desc *desc = data->desc;
170 unsigned long irq_flags;
173 data->irq = gpiod_to_irq(desc);
177 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
181 irq_flags = IRQF_SHARED;
182 if (flags & GPIO_IRQF_TRIGGER_FALLING)
183 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
184 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
185 if (flags & GPIO_IRQF_TRIGGER_RISING)
186 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
187 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
190 * FIXME: This should be done in the irq_request_resources callback
191 * when the irq is requested, but a few drivers currently fail
194 * Remove this redundant call (along with the corresponding
195 * unlock) when those drivers have been fixed.
197 ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
201 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
206 data->irq_flags = flags;
211 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
213 sysfs_put(data->value_kn);
219 * Caller holds gpiod-data mutex (unless called after class-device
222 static void gpio_sysfs_free_irq(struct device *dev)
224 struct gpiod_data *data = dev_get_drvdata(dev);
225 struct gpio_desc *desc = data->desc;
228 free_irq(data->irq, data);
229 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
230 sysfs_put(data->value_kn);
233 static const char * const trigger_names[] = {
234 [GPIO_IRQF_TRIGGER_NONE] = "none",
235 [GPIO_IRQF_TRIGGER_FALLING] = "falling",
236 [GPIO_IRQF_TRIGGER_RISING] = "rising",
237 [GPIO_IRQF_TRIGGER_BOTH] = "both",
240 static ssize_t edge_show(struct device *dev,
241 struct device_attribute *attr, char *buf)
243 struct gpiod_data *data = dev_get_drvdata(dev);
246 mutex_lock(&data->mutex);
248 flags = data->irq_flags;
250 mutex_unlock(&data->mutex);
252 if (flags >= ARRAY_SIZE(trigger_names))
255 return sysfs_emit(buf, "%s\n", trigger_names[flags]);
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);
262 ssize_t status = size;
265 flags = sysfs_match_string(trigger_names, buf);
269 mutex_lock(&data->mutex);
271 if (flags == data->irq_flags) {
277 gpio_sysfs_free_irq(dev);
280 status = gpio_sysfs_request_irq(dev, flags);
286 mutex_unlock(&data->mutex);
290 static DEVICE_ATTR_RW(edge);
292 /* Caller holds gpiod-data mutex. */
293 static int gpio_sysfs_set_active_low(struct device *dev, int value)
295 struct gpiod_data *data = dev_get_drvdata(dev);
296 unsigned int flags = data->irq_flags;
297 struct gpio_desc *desc = data->desc;
301 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
304 assign_bit(FLAG_ACTIVE_LOW, &desc->flags, value);
306 /* reconfigure poll(2) support if enabled on one edge only */
307 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
308 flags == GPIO_IRQF_TRIGGER_RISING) {
309 gpio_sysfs_free_irq(dev);
310 status = gpio_sysfs_request_irq(dev, flags);
316 static ssize_t active_low_show(struct device *dev,
317 struct device_attribute *attr, char *buf)
319 struct gpiod_data *data = dev_get_drvdata(dev);
320 struct gpio_desc *desc = data->desc;
323 mutex_lock(&data->mutex);
325 value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags);
327 mutex_unlock(&data->mutex);
329 return sysfs_emit(buf, "%d\n", value);
332 static ssize_t active_low_store(struct device *dev,
333 struct device_attribute *attr, const char *buf, size_t size)
335 struct gpiod_data *data = dev_get_drvdata(dev);
339 status = kstrtol(buf, 0, &value);
343 mutex_lock(&data->mutex);
345 status = gpio_sysfs_set_active_low(dev, value);
347 mutex_unlock(&data->mutex);
349 return status ? : size;
351 static DEVICE_ATTR_RW(active_low);
353 static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
356 struct device *dev = kobj_to_dev(kobj);
357 struct gpiod_data *data = dev_get_drvdata(dev);
358 struct gpio_desc *desc = data->desc;
359 umode_t mode = attr->mode;
360 bool show_direction = data->direction_can_change;
362 if (attr == &dev_attr_direction.attr) {
365 } else if (attr == &dev_attr_edge.attr) {
366 if (gpiod_to_irq(desc) < 0)
368 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
375 static struct attribute *gpio_attrs[] = {
376 &dev_attr_direction.attr,
378 &dev_attr_value.attr,
379 &dev_attr_active_low.attr,
383 static const struct attribute_group gpio_group = {
385 .is_visible = gpio_is_visible,
388 static const struct attribute_group *gpio_groups[] = {
394 * /sys/class/gpio/gpiochipN/
395 * /base ... matching gpio_chip.base (N)
396 * /label ... matching gpio_chip.label
397 * /ngpio ... matching gpio_chip.ngpio
400 static ssize_t base_show(struct device *dev,
401 struct device_attribute *attr, char *buf)
403 const struct gpio_chip *chip = dev_get_drvdata(dev);
405 return sysfs_emit(buf, "%d\n", chip->base);
407 static DEVICE_ATTR_RO(base);
409 static ssize_t label_show(struct device *dev,
410 struct device_attribute *attr, char *buf)
412 const struct gpio_chip *chip = dev_get_drvdata(dev);
414 return sysfs_emit(buf, "%s\n", chip->label ?: "");
416 static DEVICE_ATTR_RO(label);
418 static ssize_t ngpio_show(struct device *dev,
419 struct device_attribute *attr, char *buf)
421 const struct gpio_chip *chip = dev_get_drvdata(dev);
423 return sysfs_emit(buf, "%u\n", chip->ngpio);
425 static DEVICE_ATTR_RO(ngpio);
427 static struct attribute *gpiochip_attrs[] = {
429 &dev_attr_label.attr,
430 &dev_attr_ngpio.attr,
433 ATTRIBUTE_GROUPS(gpiochip);
436 * /sys/class/gpio/export ... write-only
437 * integer N ... number of GPIO to export (full access)
438 * /sys/class/gpio/unexport ... write-only
439 * integer N ... number of GPIO to unexport
441 static ssize_t export_store(const struct class *class,
442 const struct class_attribute *attr,
443 const char *buf, size_t len)
445 struct gpio_desc *desc;
446 struct gpio_chip *gc;
450 status = kstrtol(buf, 0, &gpio);
454 desc = gpio_to_desc(gpio);
455 /* reject invalid GPIOs */
457 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
460 gc = desc->gdev->chip;
461 offset = gpio_chip_hwgpio(desc);
462 if (!gpiochip_line_is_valid(gc, offset)) {
463 pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
467 /* No extra locking here; FLAG_SYSFS just signifies that the
468 * request and export were done by on behalf of userspace, so
469 * they may be undone on its behalf too.
472 status = gpiod_request_user(desc, "sysfs");
476 status = gpiod_set_transitory(desc, false);
482 status = gpiod_export(desc, true);
486 set_bit(FLAG_SYSFS, &desc->flags);
490 pr_debug("%s: status %d\n", __func__, status);
491 return status ? : len;
493 static CLASS_ATTR_WO(export);
495 static ssize_t unexport_store(const struct class *class,
496 const struct class_attribute *attr,
497 const char *buf, size_t len)
499 struct gpio_desc *desc;
503 status = kstrtol(buf, 0, &gpio);
507 desc = gpio_to_desc(gpio);
508 /* reject bogus commands (gpiod_unexport() ignores them) */
510 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
516 /* No extra locking here; FLAG_SYSFS just signifies that the
517 * request and export were done by on behalf of userspace, so
518 * they may be undone on its behalf too.
520 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
521 gpiod_unexport(desc);
527 pr_debug("%s: status %d\n", __func__, status);
528 return status ? : len;
530 static CLASS_ATTR_WO(unexport);
532 static struct attribute *gpio_class_attrs[] = {
533 &class_attr_export.attr,
534 &class_attr_unexport.attr,
537 ATTRIBUTE_GROUPS(gpio_class);
539 static struct class gpio_class = {
541 .class_groups = gpio_class_groups,
546 * gpiod_export - export a GPIO through sysfs
547 * @desc: GPIO to make available, already requested
548 * @direction_may_change: true if userspace may change GPIO direction
549 * Context: arch_initcall or later
551 * When drivers want to make a GPIO accessible to userspace after they
552 * have requested it -- perhaps while debugging, or as part of their
553 * public interface -- they may use this routine. If the GPIO can
554 * change direction (some can't) and the caller allows it, userspace
555 * will see "direction" sysfs attribute which may be used to change
556 * the gpio's direction. A "value" attribute will always be provided.
558 * Returns zero on success, else an error.
560 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
562 const char *ioname = NULL;
563 struct gpio_device *gdev;
564 struct gpiod_data *data;
565 struct gpio_chip *chip;
570 /* can't export until sysfs is available ... */
571 if (!class_is_registered(&gpio_class)) {
572 pr_debug("%s: called too early!\n", __func__);
577 pr_debug("%s: invalid gpio descriptor\n", __func__);
584 mutex_lock(&sysfs_lock);
586 /* check if chip is being removed */
587 if (!chip || !gdev->mockdev) {
592 spin_lock_irqsave(&gpio_lock, flags);
593 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
594 test_bit(FLAG_EXPORT, &desc->flags)) {
595 spin_unlock_irqrestore(&gpio_lock, flags);
596 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
598 test_bit(FLAG_REQUESTED, &desc->flags),
599 test_bit(FLAG_EXPORT, &desc->flags));
603 spin_unlock_irqrestore(&gpio_lock, flags);
605 data = kzalloc(sizeof(*data), GFP_KERNEL);
612 mutex_init(&data->mutex);
613 if (chip->direction_input && chip->direction_output)
614 data->direction_can_change = direction_may_change;
616 data->direction_can_change = false;
618 offset = gpio_chip_hwgpio(desc);
619 if (chip->names && chip->names[offset])
620 ioname = chip->names[offset];
622 dev = device_create_with_groups(&gpio_class, &gdev->dev,
623 MKDEV(0, 0), data, gpio_groups,
624 ioname ? ioname : "gpio%u",
627 status = PTR_ERR(dev);
631 set_bit(FLAG_EXPORT, &desc->flags);
632 mutex_unlock(&sysfs_lock);
638 mutex_unlock(&sysfs_lock);
639 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
642 EXPORT_SYMBOL_GPL(gpiod_export);
644 static int match_export(struct device *dev, const void *desc)
646 struct gpiod_data *data = dev_get_drvdata(dev);
648 return data->desc == desc;
652 * gpiod_export_link - create a sysfs link to an exported GPIO node
653 * @dev: device under which to create symlink
654 * @name: name of the symlink
655 * @desc: GPIO to create symlink to, already exported
657 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
658 * node. Caller is responsible for unlinking.
660 * Returns zero on success, else an error.
662 int gpiod_export_link(struct device *dev, const char *name,
663 struct gpio_desc *desc)
669 pr_warn("%s: invalid GPIO\n", __func__);
673 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
677 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
682 EXPORT_SYMBOL_GPL(gpiod_export_link);
685 * gpiod_unexport - reverse effect of gpiod_export()
686 * @desc: GPIO to make unavailable
688 * This is implicit on gpiod_free().
690 void gpiod_unexport(struct gpio_desc *desc)
692 struct gpiod_data *data;
696 pr_warn("%s: invalid GPIO\n", __func__);
700 mutex_lock(&sysfs_lock);
702 if (!test_bit(FLAG_EXPORT, &desc->flags))
705 dev = class_find_device(&gpio_class, NULL, desc, match_export);
709 data = dev_get_drvdata(dev);
711 clear_bit(FLAG_EXPORT, &desc->flags);
713 device_unregister(dev);
716 * Release irq after deregistration to prevent race with edge_store.
719 gpio_sysfs_free_irq(dev);
721 mutex_unlock(&sysfs_lock);
729 mutex_unlock(&sysfs_lock);
731 EXPORT_SYMBOL_GPL(gpiod_unexport);
733 int gpiochip_sysfs_register(struct gpio_device *gdev)
735 struct gpio_chip *chip = gdev->chip;
736 struct device *parent;
740 * Many systems add gpio chips for SOC support very early,
741 * before driver model support is available. In those cases we
742 * register later, in gpiolib_sysfs_init() ... here we just
743 * verify that _some_ field of gpio_class got initialized.
745 if (!class_is_registered(&gpio_class))
749 * For sysfs backward compatibility we need to preserve this
750 * preferred parenting to the gpio_chip parent field, if set.
753 parent = chip->parent;
757 /* use chip->base for the ID; it's already known to be unique */
758 dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), chip,
759 gpiochip_groups, GPIOCHIP_NAME "%d",
764 mutex_lock(&sysfs_lock);
766 mutex_unlock(&sysfs_lock);
771 void gpiochip_sysfs_unregister(struct gpio_device *gdev)
773 struct gpio_desc *desc;
774 struct gpio_chip *chip = gdev->chip;
779 device_unregister(gdev->mockdev);
781 /* prevent further gpiod exports */
782 mutex_lock(&sysfs_lock);
783 gdev->mockdev = NULL;
784 mutex_unlock(&sysfs_lock);
786 /* unregister gpiod class devices owned by sysfs */
787 for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) {
788 gpiod_unexport(desc);
793 static int __init gpiolib_sysfs_init(void)
797 struct gpio_device *gdev;
799 status = class_register(&gpio_class);
803 /* Scan and register the gpio_chips which registered very
804 * early (e.g. before the class_register above was called).
806 * We run before arch_initcall() so chip->dev nodes can have
807 * registered, and so arch_initcall() can always gpiod_export().
809 spin_lock_irqsave(&gpio_lock, flags);
810 list_for_each_entry(gdev, &gpio_devices, list) {
815 * TODO we yield gpio_lock here because
816 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
817 * and needs to be fixed.
819 * Also it would be nice to use gpio_device_find() here so we
820 * can keep gpio_chips local to gpiolib.c, but the yield of
821 * gpio_lock prevents us from doing this.
823 spin_unlock_irqrestore(&gpio_lock, flags);
824 status = gpiochip_sysfs_register(gdev);
825 spin_lock_irqsave(&gpio_lock, flags);
827 spin_unlock_irqrestore(&gpio_lock, flags);
831 postcore_initcall(gpiolib_sysfs_init);