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);
503 status = gpiod_export(desc, true);
507 set_bit(FLAG_SYSFS, &desc->flags);
511 pr_debug("%s: status %d\n", __func__, status);
512 return status ? : len;
514 static CLASS_ATTR_WO(export);
516 static ssize_t unexport_store(struct class *class,
517 struct class_attribute *attr,
518 const char *buf, size_t len)
521 struct gpio_desc *desc;
524 status = kstrtol(buf, 0, &gpio);
528 desc = gpio_to_valid_desc(gpio);
529 /* reject bogus commands (gpio_unexport ignores them) */
531 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
537 /* No extra locking here; FLAG_SYSFS just signifies that the
538 * request and export were done by on behalf of userspace, so
539 * they may be undone on its behalf too.
541 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
547 pr_debug("%s: status %d\n", __func__, status);
548 return status ? : len;
550 static CLASS_ATTR_WO(unexport);
552 static struct attribute *gpio_class_attrs[] = {
553 &class_attr_export.attr,
554 &class_attr_unexport.attr,
557 ATTRIBUTE_GROUPS(gpio_class);
559 static struct class gpio_class = {
561 .owner = THIS_MODULE,
563 .class_groups = gpio_class_groups,
568 * gpiod_export - export a GPIO through sysfs
569 * @desc: GPIO to make available, already requested
570 * @direction_may_change: true if userspace may change GPIO direction
571 * Context: arch_initcall or later
573 * When drivers want to make a GPIO accessible to userspace after they
574 * have requested it -- perhaps while debugging, or as part of their
575 * public interface -- they may use this routine. If the GPIO can
576 * change direction (some can't) and the caller allows it, userspace
577 * will see "direction" sysfs attribute which may be used to change
578 * the gpio's direction. A "value" attribute will always be provided.
580 * Returns zero on success, else an error.
582 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
584 struct gpio_chip *chip;
585 struct gpio_device *gdev;
586 struct gpiod_data *data;
589 const char *ioname = NULL;
593 /* can't export until sysfs is available ... */
595 pr_debug("%s: called too early!\n", __func__);
600 pr_debug("%s: invalid gpio descriptor\n", __func__);
607 mutex_lock(&sysfs_lock);
609 /* check if chip is being removed */
610 if (!chip || !gdev->mockdev) {
615 spin_lock_irqsave(&gpio_lock, flags);
616 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
617 test_bit(FLAG_EXPORT, &desc->flags)) {
618 spin_unlock_irqrestore(&gpio_lock, flags);
619 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
621 test_bit(FLAG_REQUESTED, &desc->flags),
622 test_bit(FLAG_EXPORT, &desc->flags));
626 spin_unlock_irqrestore(&gpio_lock, flags);
628 data = kzalloc(sizeof(*data), GFP_KERNEL);
635 mutex_init(&data->mutex);
636 if (chip->direction_input && chip->direction_output)
637 data->direction_can_change = direction_may_change;
639 data->direction_can_change = false;
641 offset = gpio_chip_hwgpio(desc);
642 if (chip->names && chip->names[offset])
643 ioname = chip->names[offset];
645 dev = device_create_with_groups(&gpio_class, &gdev->dev,
646 MKDEV(0, 0), data, gpio_groups,
647 ioname ? ioname : "gpio%u",
650 status = PTR_ERR(dev);
654 set_bit(FLAG_EXPORT, &desc->flags);
655 mutex_unlock(&sysfs_lock);
661 mutex_unlock(&sysfs_lock);
662 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
665 EXPORT_SYMBOL_GPL(gpiod_export);
667 static int match_export(struct device *dev, const void *desc)
669 struct gpiod_data *data = dev_get_drvdata(dev);
671 return data->desc == desc;
675 * gpiod_export_link - create a sysfs link to an exported GPIO node
676 * @dev: device under which to create symlink
677 * @name: name of the symlink
678 * @desc: GPIO to create symlink to, already exported
680 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
681 * node. Caller is responsible for unlinking.
683 * Returns zero on success, else an error.
685 int gpiod_export_link(struct device *dev, const char *name,
686 struct gpio_desc *desc)
692 pr_warn("%s: invalid GPIO\n", __func__);
696 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
700 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
705 EXPORT_SYMBOL_GPL(gpiod_export_link);
708 * gpiod_unexport - reverse effect of gpiod_export()
709 * @desc: GPIO to make unavailable
711 * This is implicit on gpiod_free().
713 void gpiod_unexport(struct gpio_desc *desc)
715 struct gpiod_data *data;
719 pr_warn("%s: invalid GPIO\n", __func__);
723 mutex_lock(&sysfs_lock);
725 if (!test_bit(FLAG_EXPORT, &desc->flags))
728 dev = class_find_device(&gpio_class, NULL, desc, match_export);
732 data = dev_get_drvdata(dev);
734 clear_bit(FLAG_EXPORT, &desc->flags);
736 device_unregister(dev);
739 * Release irq after deregistration to prevent race with edge_store.
742 gpio_sysfs_free_irq(dev);
744 mutex_unlock(&sysfs_lock);
752 mutex_unlock(&sysfs_lock);
754 EXPORT_SYMBOL_GPL(gpiod_unexport);
756 int gpiochip_sysfs_register(struct gpio_device *gdev)
759 struct device *parent;
760 struct gpio_chip *chip = gdev->chip;
763 * Many systems add gpio chips for SOC support very early,
764 * before driver model support is available. In those cases we
765 * register later, in gpiolib_sysfs_init() ... here we just
766 * verify that _some_ field of gpio_class got initialized.
772 * For sysfs backward compatibility we need to preserve this
773 * preferred parenting to the gpio_chip parent field, if set.
776 parent = chip->parent;
780 /* use chip->base for the ID; it's already known to be unique */
781 dev = device_create_with_groups(&gpio_class, parent,
783 chip, gpiochip_groups,
784 "gpiochip%d", chip->base);
788 mutex_lock(&sysfs_lock);
790 mutex_unlock(&sysfs_lock);
795 void gpiochip_sysfs_unregister(struct gpio_device *gdev)
797 struct gpio_desc *desc;
798 struct gpio_chip *chip = gdev->chip;
804 device_unregister(gdev->mockdev);
806 /* prevent further gpiod exports */
807 mutex_lock(&sysfs_lock);
808 gdev->mockdev = NULL;
809 mutex_unlock(&sysfs_lock);
811 /* unregister gpiod class devices owned by sysfs */
812 for (i = 0; i < chip->ngpio; i++) {
813 desc = &gdev->descs[i];
814 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags))
819 static int __init gpiolib_sysfs_init(void)
823 struct gpio_device *gdev;
825 status = class_register(&gpio_class);
829 /* Scan and register the gpio_chips which registered very
830 * early (e.g. before the class_register above was called).
832 * We run before arch_initcall() so chip->dev nodes can have
833 * registered, and so arch_initcall() can always gpio_export().
835 spin_lock_irqsave(&gpio_lock, flags);
836 list_for_each_entry(gdev, &gpio_devices, list) {
841 * TODO we yield gpio_lock here because
842 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
843 * and needs to be fixed.
845 * Also it would be nice to use gpiochip_find() here so we
846 * can keep gpio_chips local to gpiolib.c, but the yield of
847 * gpio_lock prevents us from doing this.
849 spin_unlock_irqrestore(&gpio_lock, flags);
850 status = gpiochip_sysfs_register(gdev);
851 spin_lock_irqsave(&gpio_lock, flags);
853 spin_unlock_irqrestore(&gpio_lock, flags);
857 postcore_initcall(gpiolib_sysfs_init);