2 #include <linux/mutex.h>
3 #include <linux/device.h>
4 #include <linux/sysfs.h>
5 #include <linux/gpio.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);
447 static struct gpio_desc *gpio_to_valid_desc(int gpio)
449 return gpio_is_valid(gpio) ? gpio_to_desc(gpio) : NULL;
453 * /sys/class/gpio/export ... write-only
454 * integer N ... number of GPIO to export (full access)
455 * /sys/class/gpio/unexport ... write-only
456 * integer N ... number of GPIO to unexport
458 static ssize_t export_store(struct class *class,
459 struct class_attribute *attr,
460 const char *buf, size_t len)
463 struct gpio_desc *desc;
465 struct gpio_chip *gc;
468 status = kstrtol(buf, 0, &gpio);
472 desc = gpio_to_valid_desc(gpio);
473 /* reject invalid GPIOs */
475 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
478 gc = desc->gdev->chip;
479 offset = gpio_chip_hwgpio(desc);
480 if (!gpiochip_line_is_valid(gc, offset)) {
481 pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
485 /* No extra locking here; FLAG_SYSFS just signifies that the
486 * request and export were done by on behalf of userspace, so
487 * they may be undone on its behalf too.
490 status = gpiod_request(desc, "sysfs");
492 if (status == -EPROBE_DEFER)
497 status = gpiod_set_transitory(desc, false);
499 status = gpiod_export(desc, true);
503 set_bit(FLAG_SYSFS, &desc->flags);
508 pr_debug("%s: status %d\n", __func__, status);
509 return status ? : len;
511 static CLASS_ATTR_WO(export);
513 static ssize_t unexport_store(struct class *class,
514 struct class_attribute *attr,
515 const char *buf, size_t len)
518 struct gpio_desc *desc;
521 status = kstrtol(buf, 0, &gpio);
525 desc = gpio_to_valid_desc(gpio);
526 /* reject bogus commands (gpio_unexport ignores them) */
528 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
534 /* No extra locking here; FLAG_SYSFS just signifies that the
535 * request and export were done by on behalf of userspace, so
536 * they may be undone on its behalf too.
538 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
544 pr_debug("%s: status %d\n", __func__, status);
545 return status ? : len;
547 static CLASS_ATTR_WO(unexport);
549 static struct attribute *gpio_class_attrs[] = {
550 &class_attr_export.attr,
551 &class_attr_unexport.attr,
554 ATTRIBUTE_GROUPS(gpio_class);
556 static struct class gpio_class = {
558 .owner = THIS_MODULE,
560 .class_groups = gpio_class_groups,
565 * gpiod_export - export a GPIO through sysfs
566 * @desc: GPIO to make available, already requested
567 * @direction_may_change: true if userspace may change GPIO direction
568 * Context: arch_initcall or later
570 * When drivers want to make a GPIO accessible to userspace after they
571 * have requested it -- perhaps while debugging, or as part of their
572 * public interface -- they may use this routine. If the GPIO can
573 * change direction (some can't) and the caller allows it, userspace
574 * will see "direction" sysfs attribute which may be used to change
575 * the gpio's direction. A "value" attribute will always be provided.
577 * Returns zero on success, else an error.
579 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
581 struct gpio_chip *chip;
582 struct gpio_device *gdev;
583 struct gpiod_data *data;
586 const char *ioname = NULL;
590 /* can't export until sysfs is available ... */
592 pr_debug("%s: called too early!\n", __func__);
597 pr_debug("%s: invalid gpio descriptor\n", __func__);
604 mutex_lock(&sysfs_lock);
606 /* check if chip is being removed */
607 if (!chip || !gdev->mockdev) {
612 spin_lock_irqsave(&gpio_lock, flags);
613 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
614 test_bit(FLAG_EXPORT, &desc->flags)) {
615 spin_unlock_irqrestore(&gpio_lock, flags);
616 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
618 test_bit(FLAG_REQUESTED, &desc->flags),
619 test_bit(FLAG_EXPORT, &desc->flags));
623 spin_unlock_irqrestore(&gpio_lock, flags);
625 data = kzalloc(sizeof(*data), GFP_KERNEL);
632 mutex_init(&data->mutex);
633 if (chip->direction_input && chip->direction_output)
634 data->direction_can_change = direction_may_change;
636 data->direction_can_change = false;
638 offset = gpio_chip_hwgpio(desc);
639 if (chip->names && chip->names[offset])
640 ioname = chip->names[offset];
642 dev = device_create_with_groups(&gpio_class, &gdev->dev,
643 MKDEV(0, 0), data, gpio_groups,
644 ioname ? ioname : "gpio%u",
647 status = PTR_ERR(dev);
651 set_bit(FLAG_EXPORT, &desc->flags);
652 mutex_unlock(&sysfs_lock);
658 mutex_unlock(&sysfs_lock);
659 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
662 EXPORT_SYMBOL_GPL(gpiod_export);
664 static int match_export(struct device *dev, const void *desc)
666 struct gpiod_data *data = dev_get_drvdata(dev);
668 return data->desc == desc;
672 * gpiod_export_link - create a sysfs link to an exported GPIO node
673 * @dev: device under which to create symlink
674 * @name: name of the symlink
675 * @desc: GPIO to create symlink to, already exported
677 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
678 * node. Caller is responsible for unlinking.
680 * Returns zero on success, else an error.
682 int gpiod_export_link(struct device *dev, const char *name,
683 struct gpio_desc *desc)
689 pr_warn("%s: invalid GPIO\n", __func__);
693 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
697 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
702 EXPORT_SYMBOL_GPL(gpiod_export_link);
705 * gpiod_unexport - reverse effect of gpiod_export()
706 * @desc: GPIO to make unavailable
708 * This is implicit on gpiod_free().
710 void gpiod_unexport(struct gpio_desc *desc)
712 struct gpiod_data *data;
716 pr_warn("%s: invalid GPIO\n", __func__);
720 mutex_lock(&sysfs_lock);
722 if (!test_bit(FLAG_EXPORT, &desc->flags))
725 dev = class_find_device(&gpio_class, NULL, desc, match_export);
729 data = dev_get_drvdata(dev);
731 clear_bit(FLAG_EXPORT, &desc->flags);
733 device_unregister(dev);
736 * Release irq after deregistration to prevent race with edge_store.
739 gpio_sysfs_free_irq(dev);
741 mutex_unlock(&sysfs_lock);
749 mutex_unlock(&sysfs_lock);
751 EXPORT_SYMBOL_GPL(gpiod_unexport);
753 int gpiochip_sysfs_register(struct gpio_device *gdev)
756 struct device *parent;
757 struct gpio_chip *chip = gdev->chip;
760 * Many systems add gpio chips for SOC support very early,
761 * before driver model support is available. In those cases we
762 * register later, in gpiolib_sysfs_init() ... here we just
763 * verify that _some_ field of gpio_class got initialized.
769 * For sysfs backward compatibility we need to preserve this
770 * preferred parenting to the gpio_chip parent field, if set.
773 parent = chip->parent;
777 /* use chip->base for the ID; it's already known to be unique */
778 dev = device_create_with_groups(&gpio_class, parent,
780 chip, gpiochip_groups,
781 "gpiochip%d", chip->base);
785 mutex_lock(&sysfs_lock);
787 mutex_unlock(&sysfs_lock);
792 void gpiochip_sysfs_unregister(struct gpio_device *gdev)
794 struct gpio_desc *desc;
795 struct gpio_chip *chip = gdev->chip;
801 device_unregister(gdev->mockdev);
803 /* prevent further gpiod exports */
804 mutex_lock(&sysfs_lock);
805 gdev->mockdev = NULL;
806 mutex_unlock(&sysfs_lock);
808 /* unregister gpiod class devices owned by sysfs */
809 for (i = 0; i < chip->ngpio; i++) {
810 desc = &gdev->descs[i];
811 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags))
816 static int __init gpiolib_sysfs_init(void)
820 struct gpio_device *gdev;
822 status = class_register(&gpio_class);
826 /* Scan and register the gpio_chips which registered very
827 * early (e.g. before the class_register above was called).
829 * We run before arch_initcall() so chip->dev nodes can have
830 * registered, and so arch_initcall() can always gpio_export().
832 spin_lock_irqsave(&gpio_lock, flags);
833 list_for_each_entry(gdev, &gpio_devices, list) {
838 * TODO we yield gpio_lock here because
839 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
840 * and needs to be fixed.
842 * Also it would be nice to use gpiochip_find() here so we
843 * can keep gpio_chips local to gpiolib.c, but the yield of
844 * gpio_lock prevents us from doing this.
846 spin_unlock_irqrestore(&gpio_lock, flags);
847 status = gpiochip_sysfs_register(gdev);
848 spin_lock_irqsave(&gpio_lock, flags);
850 spin_unlock_irqrestore(&gpio_lock, flags);
854 postcore_initcall(gpiolib_sysfs_init);