1 #include <linux/kernel.h>
2 #include <linux/module.h>
3 #include <linux/interrupt.h>
5 #include <linux/spinlock.h>
6 #include <linux/list.h>
7 #include <linux/device.h>
9 #include <linux/debugfs.h>
10 #include <linux/seq_file.h>
11 #include <linux/gpio.h>
12 #include <linux/of_gpio.h>
13 #include <linux/idr.h>
14 #include <linux/slab.h>
16 #define CREATE_TRACE_POINTS
17 #include <trace/events/gpio.h>
19 /* Optional implementation infrastructure for GPIO interfaces.
21 * Platforms may want to use this if they tend to use very many GPIOs
22 * that aren't part of a System-On-Chip core; or across I2C/SPI/etc.
24 * When kernel footprint or instruction count is an issue, simpler
25 * implementations may be preferred. The GPIO programming interface
26 * allows for inlining speed-critical get/set operations for common
27 * cases, so that access to SOC-integrated GPIOs can sometimes cost
28 * only an instruction or two per bit.
32 /* When debugging, extend minimal trust to callers and platform code.
33 * Also emit diagnostic messages that may help initial bringup, when
34 * board setup or driver bugs are most common.
36 * Otherwise, minimize overhead in what may be bitbanging codepaths.
39 #define extra_checks 1
41 #define extra_checks 0
44 /* gpio_lock prevents conflicts during gpio_desc[] table updates.
45 * While any GPIO is requested, its gpio_chip is not removable;
46 * each GPIO's "requested" flag serves as a lock and refcount.
48 static DEFINE_SPINLOCK(gpio_lock);
51 struct gpio_chip *chip;
53 /* flag symbols are bit numbers */
54 #define FLAG_REQUESTED 0
56 #define FLAG_EXPORT 2 /* protected by sysfs_lock */
57 #define FLAG_SYSFS 3 /* exported via /sys/class/gpio/control */
58 #define FLAG_TRIG_FALL 4 /* trigger on falling edge */
59 #define FLAG_TRIG_RISE 5 /* trigger on rising edge */
60 #define FLAG_ACTIVE_LOW 6 /* sysfs value has active low */
61 #define FLAG_OPEN_DRAIN 7 /* Gpio is open drain type */
62 #define FLAG_OPEN_SOURCE 8 /* Gpio is open source type */
64 #define ID_SHIFT 16 /* add new flags before this one */
66 #define GPIO_FLAGS_MASK ((1 << ID_SHIFT) - 1)
67 #define GPIO_TRIGGER_MASK (BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE))
69 #ifdef CONFIG_DEBUG_FS
73 static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];
75 #define GPIO_OFFSET_VALID(chip, offset) (offset >= 0 && offset < chip->ngpio)
77 static LIST_HEAD(gpio_chips);
79 #ifdef CONFIG_GPIO_SYSFS
80 static DEFINE_IDR(dirent_idr);
84 * Internal gpiod_* API using descriptors instead of the integer namespace.
85 * Most of this should eventually go public.
87 static int gpiod_request(struct gpio_desc *desc, const char *label);
88 static void gpiod_free(struct gpio_desc *desc);
89 static int gpiod_direction_input(struct gpio_desc *desc);
90 static int gpiod_direction_output(struct gpio_desc *desc, int value);
91 static int gpiod_get_direction(const struct gpio_desc *desc);
92 static int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce);
93 static int gpiod_get_value_cansleep(const struct gpio_desc *desc);
94 static void gpiod_set_value_cansleep(struct gpio_desc *desc, int value);
95 static int gpiod_get_value(const struct gpio_desc *desc);
96 static void gpiod_set_value(struct gpio_desc *desc, int value);
97 static int gpiod_cansleep(const struct gpio_desc *desc);
98 static int gpiod_to_irq(const struct gpio_desc *desc);
99 static int gpiod_export(struct gpio_desc *desc, bool direction_may_change);
100 static int gpiod_export_link(struct device *dev, const char *name,
101 struct gpio_desc *desc);
102 static int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value);
103 static void gpiod_unexport(struct gpio_desc *desc);
106 static inline void desc_set_label(struct gpio_desc *d, const char *label)
108 #ifdef CONFIG_DEBUG_FS
114 * Return the GPIO number of the passed descriptor relative to its chip
116 static int gpio_chip_hwgpio(const struct gpio_desc *desc)
118 return desc - &desc->chip->desc[0];
122 * Convert a GPIO number to its descriptor
124 static struct gpio_desc *gpio_to_desc(unsigned gpio)
126 if (WARN(!gpio_is_valid(gpio), "invalid GPIO %d\n", gpio))
129 return &gpio_desc[gpio];
133 * Convert a GPIO descriptor to the integer namespace.
134 * This should disappear in the future but is needed since we still
135 * use GPIO numbers for error messages and sysfs nodes
137 static int desc_to_gpio(const struct gpio_desc *desc)
139 return desc->chip->base + gpio_chip_hwgpio(desc);
143 /* Warn when drivers omit gpio_request() calls -- legal but ill-advised
144 * when setting direction, and otherwise illegal. Until board setup code
145 * and drivers use explicit requests everywhere (which won't happen when
146 * those calls have no teeth) we can't avoid autorequesting. This nag
147 * message should motivate switching to explicit requests... so should
148 * the weaker cleanup after faults, compared to gpio_request().
150 * NOTE: the autorequest mechanism is going away; at this point it's
151 * only "legal" in the sense that (old) code using it won't break yet,
152 * but instead only triggers a WARN() stack dump.
154 static int gpio_ensure_requested(struct gpio_desc *desc)
156 const struct gpio_chip *chip = desc->chip;
157 const int gpio = desc_to_gpio(desc);
159 if (WARN(test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0,
160 "autorequest GPIO-%d\n", gpio)) {
161 if (!try_module_get(chip->owner)) {
162 pr_err("GPIO-%d: module can't be gotten \n", gpio);
163 clear_bit(FLAG_REQUESTED, &desc->flags);
167 desc_set_label(desc, "[auto]");
168 /* caller must chip->request() w/o spinlock */
175 static struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
177 return desc ? desc->chip : NULL;
180 /* caller holds gpio_lock *OR* gpio is marked as requested */
181 struct gpio_chip *gpio_to_chip(unsigned gpio)
183 return gpiod_to_chip(gpio_to_desc(gpio));
186 /* dynamic allocation of GPIOs, e.g. on a hotplugged device */
187 static int gpiochip_find_base(int ngpio)
189 struct gpio_chip *chip;
190 int base = ARCH_NR_GPIOS - ngpio;
192 list_for_each_entry_reverse(chip, &gpio_chips, list) {
193 /* found a free space? */
194 if (chip->base + chip->ngpio <= base)
197 /* nope, check the space right before the chip */
198 base = chip->base - ngpio;
201 if (gpio_is_valid(base)) {
202 pr_debug("%s: found new base at %d\n", __func__, base);
205 pr_err("%s: cannot find free range\n", __func__);
210 /* caller ensures gpio is valid and requested, chip->get_direction may sleep */
211 static int gpiod_get_direction(const struct gpio_desc *desc)
213 struct gpio_chip *chip;
215 int status = -EINVAL;
217 chip = gpiod_to_chip(desc);
218 offset = gpio_chip_hwgpio(desc);
220 if (!chip->get_direction)
223 status = chip->get_direction(chip, offset);
225 /* GPIOF_DIR_IN, or other positive */
227 /* FLAG_IS_OUT is just a cache of the result of get_direction(),
228 * so it does not affect constness per se */
229 clear_bit(FLAG_IS_OUT, &((struct gpio_desc *)desc)->flags);
233 set_bit(FLAG_IS_OUT, &((struct gpio_desc *)desc)->flags);
238 #ifdef CONFIG_GPIO_SYSFS
240 /* lock protects against unexport_gpio() being called while
241 * sysfs files are active.
243 static DEFINE_MUTEX(sysfs_lock);
246 * /sys/class/gpio/gpioN... only for GPIOs that are exported
248 * * MAY BE OMITTED if kernel won't allow direction changes
249 * * is read/write as "in" or "out"
250 * * may also be written as "high" or "low", initializing
251 * output value as specified ("out" implies "low")
253 * * always readable, subject to hardware behavior
254 * * may be writable, as zero/nonzero
256 * * configures behavior of poll(2) on /value
257 * * available only if pin can generate IRQs on input
258 * * is read/write as "none", "falling", "rising", or "both"
260 * * configures polarity of /value
261 * * is read/write as zero/nonzero
262 * * also affects existing and subsequent "falling" and "rising"
263 * /edge configuration
266 static ssize_t gpio_direction_show(struct device *dev,
267 struct device_attribute *attr, char *buf)
269 const struct gpio_desc *desc = dev_get_drvdata(dev);
272 mutex_lock(&sysfs_lock);
274 if (!test_bit(FLAG_EXPORT, &desc->flags)) {
277 gpiod_get_direction(desc);
278 status = sprintf(buf, "%s\n",
279 test_bit(FLAG_IS_OUT, &desc->flags)
283 mutex_unlock(&sysfs_lock);
287 static ssize_t gpio_direction_store(struct device *dev,
288 struct device_attribute *attr, const char *buf, size_t size)
290 struct gpio_desc *desc = dev_get_drvdata(dev);
293 mutex_lock(&sysfs_lock);
295 if (!test_bit(FLAG_EXPORT, &desc->flags))
297 else if (sysfs_streq(buf, "high"))
298 status = gpiod_direction_output(desc, 1);
299 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
300 status = gpiod_direction_output(desc, 0);
301 else if (sysfs_streq(buf, "in"))
302 status = gpiod_direction_input(desc);
306 mutex_unlock(&sysfs_lock);
307 return status ? : size;
310 static /* const */ DEVICE_ATTR(direction, 0644,
311 gpio_direction_show, gpio_direction_store);
313 static ssize_t gpio_value_show(struct device *dev,
314 struct device_attribute *attr, char *buf)
316 struct gpio_desc *desc = dev_get_drvdata(dev);
319 mutex_lock(&sysfs_lock);
321 if (!test_bit(FLAG_EXPORT, &desc->flags)) {
326 value = !!gpiod_get_value_cansleep(desc);
327 if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
330 status = sprintf(buf, "%d\n", value);
333 mutex_unlock(&sysfs_lock);
337 static ssize_t gpio_value_store(struct device *dev,
338 struct device_attribute *attr, const char *buf, size_t size)
340 struct gpio_desc *desc = dev_get_drvdata(dev);
343 mutex_lock(&sysfs_lock);
345 if (!test_bit(FLAG_EXPORT, &desc->flags))
347 else if (!test_bit(FLAG_IS_OUT, &desc->flags))
352 status = strict_strtol(buf, 0, &value);
354 if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
356 gpiod_set_value_cansleep(desc, value != 0);
361 mutex_unlock(&sysfs_lock);
365 static DEVICE_ATTR(value, 0644,
366 gpio_value_show, gpio_value_store);
368 static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
370 struct sysfs_dirent *value_sd = priv;
372 sysfs_notify_dirent(value_sd);
376 static int gpio_setup_irq(struct gpio_desc *desc, struct device *dev,
377 unsigned long gpio_flags)
379 struct sysfs_dirent *value_sd;
380 unsigned long irq_flags;
383 if ((desc->flags & GPIO_TRIGGER_MASK) == gpio_flags)
386 irq = gpiod_to_irq(desc);
390 id = desc->flags >> ID_SHIFT;
391 value_sd = idr_find(&dirent_idr, id);
393 free_irq(irq, value_sd);
395 desc->flags &= ~GPIO_TRIGGER_MASK;
402 irq_flags = IRQF_SHARED;
403 if (test_bit(FLAG_TRIG_FALL, &gpio_flags))
404 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
405 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
406 if (test_bit(FLAG_TRIG_RISE, &gpio_flags))
407 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
408 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
411 value_sd = sysfs_get_dirent(dev->kobj.sd, NULL, "value");
417 ret = idr_alloc(&dirent_idr, value_sd, 1, 0, GFP_KERNEL);
422 desc->flags &= GPIO_FLAGS_MASK;
423 desc->flags |= (unsigned long)id << ID_SHIFT;
425 if (desc->flags >> ID_SHIFT != id) {
431 ret = request_any_context_irq(irq, gpio_sysfs_irq, irq_flags,
432 "gpiolib", value_sd);
436 desc->flags |= gpio_flags;
440 idr_remove(&dirent_idr, id);
441 desc->flags &= GPIO_FLAGS_MASK;
449 static const struct {
452 } trigger_types[] = {
454 { "falling", BIT(FLAG_TRIG_FALL) },
455 { "rising", BIT(FLAG_TRIG_RISE) },
456 { "both", BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE) },
459 static ssize_t gpio_edge_show(struct device *dev,
460 struct device_attribute *attr, char *buf)
462 const struct gpio_desc *desc = dev_get_drvdata(dev);
465 mutex_lock(&sysfs_lock);
467 if (!test_bit(FLAG_EXPORT, &desc->flags))
473 for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
474 if ((desc->flags & GPIO_TRIGGER_MASK)
475 == trigger_types[i].flags) {
476 status = sprintf(buf, "%s\n",
477 trigger_types[i].name);
482 mutex_unlock(&sysfs_lock);
486 static ssize_t gpio_edge_store(struct device *dev,
487 struct device_attribute *attr, const char *buf, size_t size)
489 struct gpio_desc *desc = dev_get_drvdata(dev);
493 for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
494 if (sysfs_streq(trigger_types[i].name, buf))
499 mutex_lock(&sysfs_lock);
501 if (!test_bit(FLAG_EXPORT, &desc->flags))
504 status = gpio_setup_irq(desc, dev, trigger_types[i].flags);
509 mutex_unlock(&sysfs_lock);
514 static DEVICE_ATTR(edge, 0644, gpio_edge_show, gpio_edge_store);
516 static int sysfs_set_active_low(struct gpio_desc *desc, struct device *dev,
521 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
525 set_bit(FLAG_ACTIVE_LOW, &desc->flags);
527 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
529 /* reconfigure poll(2) support if enabled on one edge only */
530 if (dev != NULL && (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^
531 !!test_bit(FLAG_TRIG_FALL, &desc->flags))) {
532 unsigned long trigger_flags = desc->flags & GPIO_TRIGGER_MASK;
534 gpio_setup_irq(desc, dev, 0);
535 status = gpio_setup_irq(desc, dev, trigger_flags);
541 static ssize_t gpio_active_low_show(struct device *dev,
542 struct device_attribute *attr, char *buf)
544 const struct gpio_desc *desc = dev_get_drvdata(dev);
547 mutex_lock(&sysfs_lock);
549 if (!test_bit(FLAG_EXPORT, &desc->flags))
552 status = sprintf(buf, "%d\n",
553 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
555 mutex_unlock(&sysfs_lock);
560 static ssize_t gpio_active_low_store(struct device *dev,
561 struct device_attribute *attr, const char *buf, size_t size)
563 struct gpio_desc *desc = dev_get_drvdata(dev);
566 mutex_lock(&sysfs_lock);
568 if (!test_bit(FLAG_EXPORT, &desc->flags)) {
573 status = strict_strtol(buf, 0, &value);
575 status = sysfs_set_active_low(desc, dev, value != 0);
578 mutex_unlock(&sysfs_lock);
580 return status ? : size;
583 static DEVICE_ATTR(active_low, 0644,
584 gpio_active_low_show, gpio_active_low_store);
586 static struct attribute *gpio_attrs[] = {
587 &dev_attr_value.attr,
588 &dev_attr_active_low.attr,
592 static const struct attribute_group gpio_attr_group = {
597 * /sys/class/gpio/gpiochipN/
598 * /base ... matching gpio_chip.base (N)
599 * /label ... matching gpio_chip.label
600 * /ngpio ... matching gpio_chip.ngpio
603 static ssize_t chip_base_show(struct device *dev,
604 struct device_attribute *attr, char *buf)
606 const struct gpio_chip *chip = dev_get_drvdata(dev);
608 return sprintf(buf, "%d\n", chip->base);
610 static DEVICE_ATTR(base, 0444, chip_base_show, NULL);
612 static ssize_t chip_label_show(struct device *dev,
613 struct device_attribute *attr, char *buf)
615 const struct gpio_chip *chip = dev_get_drvdata(dev);
617 return sprintf(buf, "%s\n", chip->label ? : "");
619 static DEVICE_ATTR(label, 0444, chip_label_show, NULL);
621 static ssize_t chip_ngpio_show(struct device *dev,
622 struct device_attribute *attr, char *buf)
624 const struct gpio_chip *chip = dev_get_drvdata(dev);
626 return sprintf(buf, "%u\n", chip->ngpio);
628 static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL);
630 static struct attribute *gpiochip_attrs[] = {
632 &dev_attr_label.attr,
633 &dev_attr_ngpio.attr,
637 static const struct attribute_group gpiochip_attr_group = {
638 .attrs = gpiochip_attrs,
642 * /sys/class/gpio/export ... write-only
643 * integer N ... number of GPIO to export (full access)
644 * /sys/class/gpio/unexport ... write-only
645 * integer N ... number of GPIO to unexport
647 static ssize_t export_store(struct class *class,
648 struct class_attribute *attr,
649 const char *buf, size_t len)
652 struct gpio_desc *desc;
655 status = strict_strtol(buf, 0, &gpio);
659 desc = gpio_to_desc(gpio);
660 /* reject invalid GPIOs */
662 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
666 /* No extra locking here; FLAG_SYSFS just signifies that the
667 * request and export were done by on behalf of userspace, so
668 * they may be undone on its behalf too.
671 status = gpiod_request(desc, "sysfs");
673 if (status == -EPROBE_DEFER)
677 status = gpiod_export(desc, true);
681 set_bit(FLAG_SYSFS, &desc->flags);
685 pr_debug("%s: status %d\n", __func__, status);
686 return status ? : len;
689 static ssize_t unexport_store(struct class *class,
690 struct class_attribute *attr,
691 const char *buf, size_t len)
694 struct gpio_desc *desc;
697 status = strict_strtol(buf, 0, &gpio);
701 desc = gpio_to_desc(gpio);
702 /* reject bogus commands (gpio_unexport ignores them) */
704 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
710 /* No extra locking here; FLAG_SYSFS just signifies that the
711 * request and export were done by on behalf of userspace, so
712 * they may be undone on its behalf too.
714 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
720 pr_debug("%s: status %d\n", __func__, status);
721 return status ? : len;
724 static struct class_attribute gpio_class_attrs[] = {
725 __ATTR(export, 0200, NULL, export_store),
726 __ATTR(unexport, 0200, NULL, unexport_store),
730 static struct class gpio_class = {
732 .owner = THIS_MODULE,
734 .class_attrs = gpio_class_attrs,
739 * gpio_export - export a GPIO through sysfs
740 * @gpio: gpio to make available, already requested
741 * @direction_may_change: true if userspace may change gpio direction
742 * Context: arch_initcall or later
744 * When drivers want to make a GPIO accessible to userspace after they
745 * have requested it -- perhaps while debugging, or as part of their
746 * public interface -- they may use this routine. If the GPIO can
747 * change direction (some can't) and the caller allows it, userspace
748 * will see "direction" sysfs attribute which may be used to change
749 * the gpio's direction. A "value" attribute will always be provided.
751 * Returns zero on success, else an error.
753 static int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
757 const char *ioname = NULL;
761 /* can't export until sysfs is available ... */
763 pr_debug("%s: called too early!\n", __func__);
768 pr_debug("%s: invalid gpio descriptor\n", __func__);
772 mutex_lock(&sysfs_lock);
774 spin_lock_irqsave(&gpio_lock, flags);
775 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
776 test_bit(FLAG_EXPORT, &desc->flags)) {
777 spin_unlock_irqrestore(&gpio_lock, flags);
778 pr_debug("%s: gpio %d unavailable (requested=%d, exported=%d)\n",
779 __func__, desc_to_gpio(desc),
780 test_bit(FLAG_REQUESTED, &desc->flags),
781 test_bit(FLAG_EXPORT, &desc->flags));
786 if (!desc->chip->direction_input || !desc->chip->direction_output)
787 direction_may_change = false;
788 spin_unlock_irqrestore(&gpio_lock, flags);
790 offset = gpio_chip_hwgpio(desc);
791 if (desc->chip->names && desc->chip->names[offset])
792 ioname = desc->chip->names[offset];
794 dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
795 desc, ioname ? ioname : "gpio%u",
798 status = PTR_ERR(dev);
802 status = sysfs_create_group(&dev->kobj, &gpio_attr_group);
804 goto fail_unregister_device;
806 if (direction_may_change) {
807 status = device_create_file(dev, &dev_attr_direction);
809 goto fail_remove_attr_group;
812 if (gpiod_to_irq(desc) >= 0 && (direction_may_change ||
813 !test_bit(FLAG_IS_OUT, &desc->flags))) {
814 status = device_create_file(dev, &dev_attr_edge);
816 goto fail_remove_attr_direction;
819 set_bit(FLAG_EXPORT, &desc->flags);
820 mutex_unlock(&sysfs_lock);
823 fail_remove_attr_direction:
824 device_remove_file(dev, &dev_attr_direction);
825 fail_remove_attr_group:
826 sysfs_remove_group(&dev->kobj, &gpio_attr_group);
827 fail_unregister_device:
828 device_unregister(dev);
830 mutex_unlock(&sysfs_lock);
831 pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
836 int gpio_export(unsigned gpio, bool direction_may_change)
838 return gpiod_export(gpio_to_desc(gpio), direction_may_change);
840 EXPORT_SYMBOL_GPL(gpio_export);
842 static int match_export(struct device *dev, const void *data)
844 return dev_get_drvdata(dev) == data;
848 * gpio_export_link - create a sysfs link to an exported GPIO node
849 * @dev: device under which to create symlink
850 * @name: name of the symlink
851 * @gpio: gpio to create symlink to, already exported
853 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
854 * node. Caller is responsible for unlinking.
856 * Returns zero on success, else an error.
858 static int gpiod_export_link(struct device *dev, const char *name,
859 struct gpio_desc *desc)
861 int status = -EINVAL;
864 pr_warn("%s: invalid GPIO\n", __func__);
868 mutex_lock(&sysfs_lock);
870 if (test_bit(FLAG_EXPORT, &desc->flags)) {
873 tdev = class_find_device(&gpio_class, NULL, desc, match_export);
875 status = sysfs_create_link(&dev->kobj, &tdev->kobj,
882 mutex_unlock(&sysfs_lock);
885 pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
891 int gpio_export_link(struct device *dev, const char *name, unsigned gpio)
893 return gpiod_export_link(dev, name, gpio_to_desc(gpio));
895 EXPORT_SYMBOL_GPL(gpio_export_link);
898 * gpio_sysfs_set_active_low - set the polarity of gpio sysfs value
899 * @gpio: gpio to change
900 * @value: non-zero to use active low, i.e. inverted values
902 * Set the polarity of /sys/class/gpio/gpioN/value sysfs attribute.
903 * The GPIO does not have to be exported yet. If poll(2) support has
904 * been enabled for either rising or falling edge, it will be
905 * reconfigured to follow the new polarity.
907 * Returns zero on success, else an error.
909 static int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
911 struct device *dev = NULL;
912 int status = -EINVAL;
915 pr_warn("%s: invalid GPIO\n", __func__);
919 mutex_lock(&sysfs_lock);
921 if (test_bit(FLAG_EXPORT, &desc->flags)) {
922 dev = class_find_device(&gpio_class, NULL, desc, match_export);
929 status = sysfs_set_active_low(desc, dev, value);
932 mutex_unlock(&sysfs_lock);
935 pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
941 int gpio_sysfs_set_active_low(unsigned gpio, int value)
943 return gpiod_sysfs_set_active_low(gpio_to_desc(gpio), value);
945 EXPORT_SYMBOL_GPL(gpio_sysfs_set_active_low);
948 * gpio_unexport - reverse effect of gpio_export()
949 * @gpio: gpio to make unavailable
951 * This is implicit on gpio_free().
953 static void gpiod_unexport(struct gpio_desc *desc)
956 struct device *dev = NULL;
959 pr_warn("%s: invalid GPIO\n", __func__);
963 mutex_lock(&sysfs_lock);
965 if (test_bit(FLAG_EXPORT, &desc->flags)) {
967 dev = class_find_device(&gpio_class, NULL, desc, match_export);
969 gpio_setup_irq(desc, dev, 0);
970 clear_bit(FLAG_EXPORT, &desc->flags);
975 mutex_unlock(&sysfs_lock);
978 device_remove_file(dev, &dev_attr_edge);
979 device_remove_file(dev, &dev_attr_direction);
980 sysfs_remove_group(&dev->kobj, &gpio_attr_group);
981 device_unregister(dev);
986 pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
990 void gpio_unexport(unsigned gpio)
992 gpiod_unexport(gpio_to_desc(gpio));
994 EXPORT_SYMBOL_GPL(gpio_unexport);
996 static int gpiochip_export(struct gpio_chip *chip)
1001 /* Many systems register gpio chips for SOC support very early,
1002 * before driver model support is available. In those cases we
1003 * export this later, in gpiolib_sysfs_init() ... here we just
1004 * verify that _some_ field of gpio_class got initialized.
1009 /* use chip->base for the ID; it's already known to be unique */
1010 mutex_lock(&sysfs_lock);
1011 dev = device_create(&gpio_class, chip->dev, MKDEV(0, 0), chip,
1012 "gpiochip%d", chip->base);
1014 status = sysfs_create_group(&dev->kobj,
1015 &gpiochip_attr_group);
1017 status = PTR_ERR(dev);
1018 chip->exported = (status == 0);
1019 mutex_unlock(&sysfs_lock);
1022 unsigned long flags;
1025 spin_lock_irqsave(&gpio_lock, flags);
1027 while (gpio < chip->ngpio)
1028 chip->desc[gpio++].chip = NULL;
1029 spin_unlock_irqrestore(&gpio_lock, flags);
1031 pr_debug("%s: chip %s status %d\n", __func__,
1032 chip->label, status);
1038 static void gpiochip_unexport(struct gpio_chip *chip)
1043 mutex_lock(&sysfs_lock);
1044 dev = class_find_device(&gpio_class, NULL, chip, match_export);
1046 sysfs_remove_group(&dev->kobj, &gpiochip_attr_group);
1048 device_unregister(dev);
1053 mutex_unlock(&sysfs_lock);
1056 pr_debug("%s: chip %s status %d\n", __func__,
1057 chip->label, status);
1060 static int __init gpiolib_sysfs_init(void)
1063 unsigned long flags;
1064 struct gpio_chip *chip;
1066 status = class_register(&gpio_class);
1070 /* Scan and register the gpio_chips which registered very
1071 * early (e.g. before the class_register above was called).
1073 * We run before arch_initcall() so chip->dev nodes can have
1074 * registered, and so arch_initcall() can always gpio_export().
1076 spin_lock_irqsave(&gpio_lock, flags);
1077 list_for_each_entry(chip, &gpio_chips, list) {
1078 if (!chip || chip->exported)
1081 spin_unlock_irqrestore(&gpio_lock, flags);
1082 status = gpiochip_export(chip);
1083 spin_lock_irqsave(&gpio_lock, flags);
1085 spin_unlock_irqrestore(&gpio_lock, flags);
1090 postcore_initcall(gpiolib_sysfs_init);
1093 static inline int gpiochip_export(struct gpio_chip *chip)
1098 static inline void gpiochip_unexport(struct gpio_chip *chip)
1102 static inline int gpiod_export(struct gpio_desc *desc,
1103 bool direction_may_change)
1108 static inline int gpiod_export_link(struct device *dev, const char *name,
1109 struct gpio_desc *desc)
1114 static inline int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
1119 static inline void gpiod_unexport(struct gpio_desc *desc)
1123 #endif /* CONFIG_GPIO_SYSFS */
1126 * Add a new chip to the global chips list, keeping the list of chips sorted
1129 * Return -EBUSY if the new chip overlaps with some other chip's integer
1132 static int gpiochip_add_to_list(struct gpio_chip *chip)
1134 struct list_head *pos = &gpio_chips;
1135 struct gpio_chip *_chip;
1138 /* find where to insert our chip */
1139 list_for_each(pos, &gpio_chips) {
1140 _chip = list_entry(pos, struct gpio_chip, list);
1141 /* shall we insert before _chip? */
1142 if (_chip->base >= chip->base + chip->ngpio)
1146 /* are we stepping on the chip right before? */
1147 if (pos != &gpio_chips && pos->prev != &gpio_chips) {
1148 _chip = list_entry(pos->prev, struct gpio_chip, list);
1149 if (_chip->base + _chip->ngpio > chip->base) {
1151 "GPIO integer space overlap, cannot add chip\n");
1157 list_add_tail(&chip->list, pos);
1163 * gpiochip_add() - register a gpio_chip
1164 * @chip: the chip to register, with chip->base initialized
1165 * Context: potentially before irqs or kmalloc will work
1167 * Returns a negative errno if the chip can't be registered, such as
1168 * because the chip->base is invalid or already associated with a
1169 * different chip. Otherwise it returns zero as a success code.
1171 * When gpiochip_add() is called very early during boot, so that GPIOs
1172 * can be freely used, the chip->dev device must be registered before
1173 * the gpio framework's arch_initcall(). Otherwise sysfs initialization
1174 * for GPIOs will fail rudely.
1176 * If chip->base is negative, this requests dynamic assignment of
1177 * a range of valid GPIOs.
1179 int gpiochip_add(struct gpio_chip *chip)
1181 unsigned long flags;
1184 int base = chip->base;
1186 if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
1192 spin_lock_irqsave(&gpio_lock, flags);
1195 base = gpiochip_find_base(chip->ngpio);
1203 status = gpiochip_add_to_list(chip);
1206 chip->desc = &gpio_desc[chip->base];
1208 for (id = 0; id < chip->ngpio; id++) {
1209 struct gpio_desc *desc = &chip->desc[id];
1212 /* REVISIT: most hardware initializes GPIOs as
1213 * inputs (often with pullups enabled) so power
1214 * usage is minimized. Linux code should set the
1215 * gpio direction first thing; but until it does,
1216 * and in case chip->get_direction is not set,
1217 * we may expose the wrong direction in sysfs.
1219 desc->flags = !chip->direction_input
1220 ? (1 << FLAG_IS_OUT)
1225 #ifdef CONFIG_PINCTRL
1226 INIT_LIST_HEAD(&chip->pin_ranges);
1229 of_gpiochip_add(chip);
1232 spin_unlock_irqrestore(&gpio_lock, flags);
1237 status = gpiochip_export(chip);
1241 pr_debug("gpiochip_add: registered GPIOs %d to %d on device: %s\n",
1242 chip->base, chip->base + chip->ngpio - 1,
1243 chip->label ? : "generic");
1247 /* failures here can mean systems won't boot... */
1248 pr_err("gpiochip_add: gpios %d..%d (%s) failed to register\n",
1249 chip->base, chip->base + chip->ngpio - 1,
1250 chip->label ? : "generic");
1253 EXPORT_SYMBOL_GPL(gpiochip_add);
1256 * gpiochip_remove() - unregister a gpio_chip
1257 * @chip: the chip to unregister
1259 * A gpio_chip with any GPIOs still requested may not be removed.
1261 int gpiochip_remove(struct gpio_chip *chip)
1263 unsigned long flags;
1267 spin_lock_irqsave(&gpio_lock, flags);
1269 gpiochip_remove_pin_ranges(chip);
1270 of_gpiochip_remove(chip);
1272 for (id = 0; id < chip->ngpio; id++) {
1273 if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) {
1279 for (id = 0; id < chip->ngpio; id++)
1280 chip->desc[id].chip = NULL;
1282 list_del(&chip->list);
1285 spin_unlock_irqrestore(&gpio_lock, flags);
1288 gpiochip_unexport(chip);
1292 EXPORT_SYMBOL_GPL(gpiochip_remove);
1295 * gpiochip_find() - iterator for locating a specific gpio_chip
1296 * @data: data to pass to match function
1297 * @callback: Callback function to check gpio_chip
1299 * Similar to bus_find_device. It returns a reference to a gpio_chip as
1300 * determined by a user supplied @match callback. The callback should return
1301 * 0 if the device doesn't match and non-zero if it does. If the callback is
1302 * non-zero, this function will return to the caller and not iterate over any
1305 struct gpio_chip *gpiochip_find(void *data,
1306 int (*match)(struct gpio_chip *chip,
1309 struct gpio_chip *chip;
1310 unsigned long flags;
1312 spin_lock_irqsave(&gpio_lock, flags);
1313 list_for_each_entry(chip, &gpio_chips, list)
1314 if (match(chip, data))
1318 if (&chip->list == &gpio_chips)
1320 spin_unlock_irqrestore(&gpio_lock, flags);
1324 EXPORT_SYMBOL_GPL(gpiochip_find);
1326 #ifdef CONFIG_PINCTRL
1329 * gpiochip_add_pin_range() - add a range for GPIO <-> pin mapping
1330 * @chip: the gpiochip to add the range for
1331 * @pinctrl_name: the dev_name() of the pin controller to map to
1332 * @gpio_offset: the start offset in the current gpio_chip number space
1333 * @pin_offset: the start offset in the pin controller number space
1334 * @npins: the number of pins from the offset of each pin space (GPIO and
1335 * pin controller) to accumulate in this range
1337 int gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
1338 unsigned int gpio_offset, unsigned int pin_offset,
1341 struct gpio_pin_range *pin_range;
1344 pin_range = kzalloc(sizeof(*pin_range), GFP_KERNEL);
1346 pr_err("%s: GPIO chip: failed to allocate pin ranges\n",
1351 /* Use local offset as range ID */
1352 pin_range->range.id = gpio_offset;
1353 pin_range->range.gc = chip;
1354 pin_range->range.name = chip->label;
1355 pin_range->range.base = chip->base + gpio_offset;
1356 pin_range->range.pin_base = pin_offset;
1357 pin_range->range.npins = npins;
1358 pin_range->pctldev = pinctrl_find_and_add_gpio_range(pinctl_name,
1360 if (IS_ERR(pin_range->pctldev)) {
1361 ret = PTR_ERR(pin_range->pctldev);
1362 pr_err("%s: GPIO chip: could not create pin range\n",
1367 pr_debug("GPIO chip %s: created GPIO range %d->%d ==> %s PIN %d->%d\n",
1368 chip->label, gpio_offset, gpio_offset + npins - 1,
1370 pin_offset, pin_offset + npins - 1);
1372 list_add_tail(&pin_range->node, &chip->pin_ranges);
1376 EXPORT_SYMBOL_GPL(gpiochip_add_pin_range);
1379 * gpiochip_remove_pin_ranges() - remove all the GPIO <-> pin mappings
1380 * @chip: the chip to remove all the mappings for
1382 void gpiochip_remove_pin_ranges(struct gpio_chip *chip)
1384 struct gpio_pin_range *pin_range, *tmp;
1386 list_for_each_entry_safe(pin_range, tmp, &chip->pin_ranges, node) {
1387 list_del(&pin_range->node);
1388 pinctrl_remove_gpio_range(pin_range->pctldev,
1393 EXPORT_SYMBOL_GPL(gpiochip_remove_pin_ranges);
1395 #endif /* CONFIG_PINCTRL */
1397 /* These "optional" allocation calls help prevent drivers from stomping
1398 * on each other, and help provide better diagnostics in debugfs.
1399 * They're called even less than the "set direction" calls.
1401 static int gpiod_request(struct gpio_desc *desc, const char *label)
1403 struct gpio_chip *chip;
1404 int status = -EPROBE_DEFER;
1405 unsigned long flags;
1408 pr_warn("%s: invalid GPIO\n", __func__);
1412 spin_lock_irqsave(&gpio_lock, flags);
1418 if (!try_module_get(chip->owner))
1421 /* NOTE: gpio_request() can be called in early boot,
1422 * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
1425 if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
1426 desc_set_label(desc, label ? : "?");
1430 module_put(chip->owner);
1434 if (chip->request) {
1435 /* chip->request may sleep */
1436 spin_unlock_irqrestore(&gpio_lock, flags);
1437 status = chip->request(chip, gpio_chip_hwgpio(desc));
1438 spin_lock_irqsave(&gpio_lock, flags);
1441 desc_set_label(desc, NULL);
1442 module_put(chip->owner);
1443 clear_bit(FLAG_REQUESTED, &desc->flags);
1447 if (chip->get_direction) {
1448 /* chip->get_direction may sleep */
1449 spin_unlock_irqrestore(&gpio_lock, flags);
1450 gpiod_get_direction(desc);
1451 spin_lock_irqsave(&gpio_lock, flags);
1455 pr_debug("_gpio_request: gpio-%d (%s) status %d\n",
1456 desc_to_gpio(desc), label ? : "?", status);
1457 spin_unlock_irqrestore(&gpio_lock, flags);
1461 int gpio_request(unsigned gpio, const char *label)
1463 return gpiod_request(gpio_to_desc(gpio), label);
1465 EXPORT_SYMBOL_GPL(gpio_request);
1467 static void gpiod_free(struct gpio_desc *desc)
1469 unsigned long flags;
1470 struct gpio_chip *chip;
1475 WARN_ON(extra_checks);
1479 gpiod_unexport(desc);
1481 spin_lock_irqsave(&gpio_lock, flags);
1484 if (chip && test_bit(FLAG_REQUESTED, &desc->flags)) {
1486 spin_unlock_irqrestore(&gpio_lock, flags);
1487 might_sleep_if(chip->can_sleep);
1488 chip->free(chip, gpio_chip_hwgpio(desc));
1489 spin_lock_irqsave(&gpio_lock, flags);
1491 desc_set_label(desc, NULL);
1492 module_put(desc->chip->owner);
1493 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
1494 clear_bit(FLAG_REQUESTED, &desc->flags);
1495 clear_bit(FLAG_OPEN_DRAIN, &desc->flags);
1496 clear_bit(FLAG_OPEN_SOURCE, &desc->flags);
1498 WARN_ON(extra_checks);
1500 spin_unlock_irqrestore(&gpio_lock, flags);
1503 void gpio_free(unsigned gpio)
1505 gpiod_free(gpio_to_desc(gpio));
1507 EXPORT_SYMBOL_GPL(gpio_free);
1510 * gpio_request_one - request a single GPIO with initial configuration
1511 * @gpio: the GPIO number
1512 * @flags: GPIO configuration as specified by GPIOF_*
1513 * @label: a literal description string of this GPIO
1515 int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
1517 struct gpio_desc *desc;
1520 desc = gpio_to_desc(gpio);
1522 err = gpiod_request(desc, label);
1526 if (flags & GPIOF_OPEN_DRAIN)
1527 set_bit(FLAG_OPEN_DRAIN, &desc->flags);
1529 if (flags & GPIOF_OPEN_SOURCE)
1530 set_bit(FLAG_OPEN_SOURCE, &desc->flags);
1532 if (flags & GPIOF_DIR_IN)
1533 err = gpiod_direction_input(desc);
1535 err = gpiod_direction_output(desc,
1536 (flags & GPIOF_INIT_HIGH) ? 1 : 0);
1541 if (flags & GPIOF_EXPORT) {
1542 err = gpiod_export(desc, flags & GPIOF_EXPORT_CHANGEABLE);
1553 EXPORT_SYMBOL_GPL(gpio_request_one);
1556 * gpio_request_array - request multiple GPIOs in a single call
1557 * @array: array of the 'struct gpio'
1558 * @num: how many GPIOs in the array
1560 int gpio_request_array(const struct gpio *array, size_t num)
1564 for (i = 0; i < num; i++, array++) {
1565 err = gpio_request_one(array->gpio, array->flags, array->label);
1573 gpio_free((--array)->gpio);
1576 EXPORT_SYMBOL_GPL(gpio_request_array);
1579 * gpio_free_array - release multiple GPIOs in a single call
1580 * @array: array of the 'struct gpio'
1581 * @num: how many GPIOs in the array
1583 void gpio_free_array(const struct gpio *array, size_t num)
1586 gpio_free((array++)->gpio);
1588 EXPORT_SYMBOL_GPL(gpio_free_array);
1591 * gpiochip_is_requested - return string iff signal was requested
1592 * @chip: controller managing the signal
1593 * @offset: of signal within controller's 0..(ngpio - 1) range
1595 * Returns NULL if the GPIO is not currently requested, else a string.
1596 * If debugfs support is enabled, the string returned is the label passed
1597 * to gpio_request(); otherwise it is a meaningless constant.
1599 * This function is for use by GPIO controller drivers. The label can
1600 * help with diagnostics, and knowing that the signal is used as a GPIO
1601 * can help avoid accidentally multiplexing it to another controller.
1603 const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
1605 struct gpio_desc *desc;
1607 if (!GPIO_OFFSET_VALID(chip, offset))
1610 desc = &chip->desc[offset];
1612 if (test_bit(FLAG_REQUESTED, &desc->flags) == 0)
1614 #ifdef CONFIG_DEBUG_FS
1620 EXPORT_SYMBOL_GPL(gpiochip_is_requested);
1623 /* Drivers MUST set GPIO direction before making get/set calls. In
1624 * some cases this is done in early boot, before IRQs are enabled.
1626 * As a rule these aren't called more than once (except for drivers
1627 * using the open-drain emulation idiom) so these are natural places
1628 * to accumulate extra debugging checks. Note that we can't (yet)
1629 * rely on gpio_request() having been called beforehand.
1632 static int gpiod_direction_input(struct gpio_desc *desc)
1634 unsigned long flags;
1635 struct gpio_chip *chip;
1636 int status = -EINVAL;
1640 pr_warn("%s: invalid GPIO\n", __func__);
1644 spin_lock_irqsave(&gpio_lock, flags);
1647 if (!chip || !chip->get || !chip->direction_input)
1649 status = gpio_ensure_requested(desc);
1653 /* now we know the gpio is valid and chip won't vanish */
1655 spin_unlock_irqrestore(&gpio_lock, flags);
1657 might_sleep_if(chip->can_sleep);
1659 offset = gpio_chip_hwgpio(desc);
1661 status = chip->request(chip, offset);
1663 pr_debug("GPIO-%d: chip request fail, %d\n",
1664 desc_to_gpio(desc), status);
1665 /* and it's not available to anyone else ...
1666 * gpio_request() is the fully clean solution.
1672 status = chip->direction_input(chip, offset);
1674 clear_bit(FLAG_IS_OUT, &desc->flags);
1676 trace_gpio_direction(desc_to_gpio(desc), 1, status);
1680 spin_unlock_irqrestore(&gpio_lock, flags);
1682 pr_debug("%s: gpio-%d status %d\n", __func__,
1683 desc_to_gpio(desc), status);
1687 int gpio_direction_input(unsigned gpio)
1689 return gpiod_direction_input(gpio_to_desc(gpio));
1691 EXPORT_SYMBOL_GPL(gpio_direction_input);
1693 static int gpiod_direction_output(struct gpio_desc *desc, int value)
1695 unsigned long flags;
1696 struct gpio_chip *chip;
1697 int status = -EINVAL;
1701 pr_warn("%s: invalid GPIO\n", __func__);
1705 /* Open drain pin should not be driven to 1 */
1706 if (value && test_bit(FLAG_OPEN_DRAIN, &desc->flags))
1707 return gpiod_direction_input(desc);
1709 /* Open source pin should not be driven to 0 */
1710 if (!value && test_bit(FLAG_OPEN_SOURCE, &desc->flags))
1711 return gpiod_direction_input(desc);
1713 spin_lock_irqsave(&gpio_lock, flags);
1716 if (!chip || !chip->set || !chip->direction_output)
1718 status = gpio_ensure_requested(desc);
1722 /* now we know the gpio is valid and chip won't vanish */
1724 spin_unlock_irqrestore(&gpio_lock, flags);
1726 might_sleep_if(chip->can_sleep);
1728 offset = gpio_chip_hwgpio(desc);
1730 status = chip->request(chip, offset);
1732 pr_debug("GPIO-%d: chip request fail, %d\n",
1733 desc_to_gpio(desc), status);
1734 /* and it's not available to anyone else ...
1735 * gpio_request() is the fully clean solution.
1741 status = chip->direction_output(chip, offset, value);
1743 set_bit(FLAG_IS_OUT, &desc->flags);
1744 trace_gpio_value(desc_to_gpio(desc), 0, value);
1745 trace_gpio_direction(desc_to_gpio(desc), 0, status);
1749 spin_unlock_irqrestore(&gpio_lock, flags);
1751 pr_debug("%s: gpio-%d status %d\n", __func__,
1752 desc_to_gpio(desc), status);
1756 int gpio_direction_output(unsigned gpio, int value)
1758 return gpiod_direction_output(gpio_to_desc(gpio), value);
1760 EXPORT_SYMBOL_GPL(gpio_direction_output);
1763 * gpio_set_debounce - sets @debounce time for a @gpio
1764 * @gpio: the gpio to set debounce time
1765 * @debounce: debounce time is microseconds
1767 static int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce)
1769 unsigned long flags;
1770 struct gpio_chip *chip;
1771 int status = -EINVAL;
1775 pr_warn("%s: invalid GPIO\n", __func__);
1779 spin_lock_irqsave(&gpio_lock, flags);
1782 if (!chip || !chip->set || !chip->set_debounce)
1785 status = gpio_ensure_requested(desc);
1789 /* now we know the gpio is valid and chip won't vanish */
1791 spin_unlock_irqrestore(&gpio_lock, flags);
1793 might_sleep_if(chip->can_sleep);
1795 offset = gpio_chip_hwgpio(desc);
1796 return chip->set_debounce(chip, offset, debounce);
1799 spin_unlock_irqrestore(&gpio_lock, flags);
1801 pr_debug("%s: gpio-%d status %d\n", __func__,
1802 desc_to_gpio(desc), status);
1807 int gpio_set_debounce(unsigned gpio, unsigned debounce)
1809 return gpiod_set_debounce(gpio_to_desc(gpio), debounce);
1811 EXPORT_SYMBOL_GPL(gpio_set_debounce);
1813 /* I/O calls are only valid after configuration completed; the relevant
1814 * "is this a valid GPIO" error checks should already have been done.
1816 * "Get" operations are often inlinable as reading a pin value register,
1817 * and masking the relevant bit in that register.
1819 * When "set" operations are inlinable, they involve writing that mask to
1820 * one register to set a low value, or a different register to set it high.
1821 * Otherwise locking is needed, so there may be little value to inlining.
1823 *------------------------------------------------------------------------
1825 * IMPORTANT!!! The hot paths -- get/set value -- assume that callers
1826 * have requested the GPIO. That can include implicit requesting by
1827 * a direction setting call. Marking a gpio as requested locks its chip
1828 * in memory, guaranteeing that these table lookups need no more locking
1829 * and that gpiochip_remove() will fail.
1831 * REVISIT when debugging, consider adding some instrumentation to ensure
1832 * that the GPIO was actually requested.
1836 * __gpio_get_value() - return a gpio's value
1837 * @gpio: gpio whose value will be returned
1840 * This is used directly or indirectly to implement gpio_get_value().
1841 * It returns the zero or nonzero value provided by the associated
1842 * gpio_chip.get() method; or zero if no such method is provided.
1844 static int gpiod_get_value(const struct gpio_desc *desc)
1846 struct gpio_chip *chip;
1853 offset = gpio_chip_hwgpio(desc);
1854 /* Should be using gpio_get_value_cansleep() */
1855 WARN_ON(chip->can_sleep);
1856 value = chip->get ? chip->get(chip, offset) : 0;
1857 trace_gpio_value(desc_to_gpio(desc), 1, value);
1861 int __gpio_get_value(unsigned gpio)
1863 return gpiod_get_value(gpio_to_desc(gpio));
1865 EXPORT_SYMBOL_GPL(__gpio_get_value);
1868 * _gpio_set_open_drain_value() - Set the open drain gpio's value.
1869 * @gpio: Gpio whose state need to be set.
1871 * @value: Non-zero for setting it HIGH otherise it will set to LOW.
1873 static void _gpio_set_open_drain_value(struct gpio_desc *desc, int value)
1876 struct gpio_chip *chip = desc->chip;
1877 int offset = gpio_chip_hwgpio(desc);
1880 err = chip->direction_input(chip, offset);
1882 clear_bit(FLAG_IS_OUT, &desc->flags);
1884 err = chip->direction_output(chip, offset, 0);
1886 set_bit(FLAG_IS_OUT, &desc->flags);
1888 trace_gpio_direction(desc_to_gpio(desc), value, err);
1890 pr_err("%s: Error in set_value for open drain gpio%d err %d\n",
1891 __func__, desc_to_gpio(desc), err);
1895 * _gpio_set_open_source() - Set the open source gpio's value.
1896 * @gpio: Gpio whose state need to be set.
1898 * @value: Non-zero for setting it HIGH otherise it will set to LOW.
1900 static void _gpio_set_open_source_value(struct gpio_desc *desc, int value)
1903 struct gpio_chip *chip = desc->chip;
1904 int offset = gpio_chip_hwgpio(desc);
1907 err = chip->direction_output(chip, offset, 1);
1909 set_bit(FLAG_IS_OUT, &desc->flags);
1911 err = chip->direction_input(chip, offset);
1913 clear_bit(FLAG_IS_OUT, &desc->flags);
1915 trace_gpio_direction(desc_to_gpio(desc), !value, err);
1917 pr_err("%s: Error in set_value for open source gpio%d err %d\n",
1918 __func__, desc_to_gpio(desc), err);
1922 * __gpio_set_value() - assign a gpio's value
1923 * @gpio: gpio whose value will be assigned
1924 * @value: value to assign
1927 * This is used directly or indirectly to implement gpio_set_value().
1928 * It invokes the associated gpio_chip.set() method.
1930 static void gpiod_set_value(struct gpio_desc *desc, int value)
1932 struct gpio_chip *chip;
1937 /* Should be using gpio_set_value_cansleep() */
1938 WARN_ON(chip->can_sleep);
1939 trace_gpio_value(desc_to_gpio(desc), 0, value);
1940 if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
1941 _gpio_set_open_drain_value(desc, value);
1942 else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
1943 _gpio_set_open_source_value(desc, value);
1945 chip->set(chip, gpio_chip_hwgpio(desc), value);
1948 void __gpio_set_value(unsigned gpio, int value)
1950 return gpiod_set_value(gpio_to_desc(gpio), value);
1952 EXPORT_SYMBOL_GPL(__gpio_set_value);
1955 * __gpio_cansleep() - report whether gpio value access will sleep
1956 * @gpio: gpio in question
1959 * This is used directly or indirectly to implement gpio_cansleep(). It
1960 * returns nonzero if access reading or writing the GPIO value can sleep.
1962 static int gpiod_cansleep(const struct gpio_desc *desc)
1966 /* only call this on GPIOs that are valid! */
1967 return desc->chip->can_sleep;
1970 int __gpio_cansleep(unsigned gpio)
1972 return gpiod_cansleep(gpio_to_desc(gpio));
1974 EXPORT_SYMBOL_GPL(__gpio_cansleep);
1977 * __gpio_to_irq() - return the IRQ corresponding to a GPIO
1978 * @gpio: gpio whose IRQ will be returned (already requested)
1981 * This is used directly or indirectly to implement gpio_to_irq().
1982 * It returns the number of the IRQ signaled by this (input) GPIO,
1983 * or a negative errno.
1985 static int gpiod_to_irq(const struct gpio_desc *desc)
1987 struct gpio_chip *chip;
1993 offset = gpio_chip_hwgpio(desc);
1994 return chip->to_irq ? chip->to_irq(chip, offset) : -ENXIO;
1997 int __gpio_to_irq(unsigned gpio)
1999 return gpiod_to_irq(gpio_to_desc(gpio));
2001 EXPORT_SYMBOL_GPL(__gpio_to_irq);
2004 /* There's no value in making it easy to inline GPIO calls that may sleep.
2005 * Common examples include ones connected to I2C or SPI chips.
2008 static int gpiod_get_value_cansleep(const struct gpio_desc *desc)
2010 struct gpio_chip *chip;
2014 might_sleep_if(extra_checks);
2018 offset = gpio_chip_hwgpio(desc);
2019 value = chip->get ? chip->get(chip, offset) : 0;
2020 trace_gpio_value(desc_to_gpio(desc), 1, value);
2024 int gpio_get_value_cansleep(unsigned gpio)
2026 return gpiod_get_value_cansleep(gpio_to_desc(gpio));
2028 EXPORT_SYMBOL_GPL(gpio_get_value_cansleep);
2030 static void gpiod_set_value_cansleep(struct gpio_desc *desc, int value)
2032 struct gpio_chip *chip;
2034 might_sleep_if(extra_checks);
2038 trace_gpio_value(desc_to_gpio(desc), 0, value);
2039 if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
2040 _gpio_set_open_drain_value(desc, value);
2041 else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
2042 _gpio_set_open_source_value(desc, value);
2044 chip->set(chip, gpio_chip_hwgpio(desc), value);
2047 void gpio_set_value_cansleep(unsigned gpio, int value)
2049 return gpiod_set_value_cansleep(gpio_to_desc(gpio), value);
2051 EXPORT_SYMBOL_GPL(gpio_set_value_cansleep);
2053 #ifdef CONFIG_DEBUG_FS
2055 static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
2058 unsigned gpio = chip->base;
2059 struct gpio_desc *gdesc = &chip->desc[0];
2062 for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) {
2063 if (!test_bit(FLAG_REQUESTED, &gdesc->flags))
2066 gpiod_get_direction(gdesc);
2067 is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
2068 seq_printf(s, " gpio-%-3d (%-20.20s) %s %s",
2070 is_out ? "out" : "in ",
2072 ? (chip->get(chip, i) ? "hi" : "lo")
2074 seq_printf(s, "\n");
2078 static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos)
2080 unsigned long flags;
2081 struct gpio_chip *chip = NULL;
2082 loff_t index = *pos;
2086 spin_lock_irqsave(&gpio_lock, flags);
2087 list_for_each_entry(chip, &gpio_chips, list)
2089 spin_unlock_irqrestore(&gpio_lock, flags);
2092 spin_unlock_irqrestore(&gpio_lock, flags);
2097 static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos)
2099 unsigned long flags;
2100 struct gpio_chip *chip = v;
2103 spin_lock_irqsave(&gpio_lock, flags);
2104 if (list_is_last(&chip->list, &gpio_chips))
2107 ret = list_entry(chip->list.next, struct gpio_chip, list);
2108 spin_unlock_irqrestore(&gpio_lock, flags);
2116 static void gpiolib_seq_stop(struct seq_file *s, void *v)
2120 static int gpiolib_seq_show(struct seq_file *s, void *v)
2122 struct gpio_chip *chip = v;
2125 seq_printf(s, "%sGPIOs %d-%d", (char *)s->private,
2126 chip->base, chip->base + chip->ngpio - 1);
2129 seq_printf(s, ", %s/%s", dev->bus ? dev->bus->name : "no-bus",
2132 seq_printf(s, ", %s", chip->label);
2133 if (chip->can_sleep)
2134 seq_printf(s, ", can sleep");
2135 seq_printf(s, ":\n");
2138 chip->dbg_show(s, chip);
2140 gpiolib_dbg_show(s, chip);
2145 static const struct seq_operations gpiolib_seq_ops = {
2146 .start = gpiolib_seq_start,
2147 .next = gpiolib_seq_next,
2148 .stop = gpiolib_seq_stop,
2149 .show = gpiolib_seq_show,
2152 static int gpiolib_open(struct inode *inode, struct file *file)
2154 return seq_open(file, &gpiolib_seq_ops);
2157 static const struct file_operations gpiolib_operations = {
2158 .owner = THIS_MODULE,
2159 .open = gpiolib_open,
2161 .llseek = seq_lseek,
2162 .release = seq_release,
2165 static int __init gpiolib_debugfs_init(void)
2167 /* /sys/kernel/debug/gpio */
2168 (void) debugfs_create_file("gpio", S_IFREG | S_IRUGO,
2169 NULL, NULL, &gpiolib_operations);
2172 subsys_initcall(gpiolib_debugfs_init);
2174 #endif /* DEBUG_FS */