1 #include <linux/kernel.h>
2 #include <linux/module.h>
3 #include <linux/interrupt.h>
5 #include <linux/spinlock.h>
6 #include <linux/device.h>
8 #include <linux/debugfs.h>
9 #include <linux/seq_file.h>
10 #include <linux/gpio.h>
11 #include <linux/idr.h>
12 #include <linux/slab.h>
15 /* Optional implementation infrastructure for GPIO interfaces.
17 * Platforms may want to use this if they tend to use very many GPIOs
18 * that aren't part of a System-On-Chip core; or across I2C/SPI/etc.
20 * When kernel footprint or instruction count is an issue, simpler
21 * implementations may be preferred. The GPIO programming interface
22 * allows for inlining speed-critical get/set operations for common
23 * cases, so that access to SOC-integrated GPIOs can sometimes cost
24 * only an instruction or two per bit.
28 /* When debugging, extend minimal trust to callers and platform code.
29 * Also emit diagnostic messages that may help initial bringup, when
30 * board setup or driver bugs are most common.
32 * Otherwise, minimize overhead in what may be bitbanging codepaths.
35 #define extra_checks 1
37 #define extra_checks 0
40 /* gpio_lock prevents conflicts during gpio_desc[] table updates.
41 * While any GPIO is requested, its gpio_chip is not removable;
42 * each GPIO's "requested" flag serves as a lock and refcount.
44 static DEFINE_SPINLOCK(gpio_lock
);
47 struct gpio_chip
*chip
;
49 /* flag symbols are bit numbers */
50 #define FLAG_REQUESTED 0
52 #define FLAG_RESERVED 2
53 #define FLAG_EXPORT 3 /* protected by sysfs_lock */
54 #define FLAG_SYSFS 4 /* exported via /sys/class/gpio/control */
55 #define FLAG_TRIG_FALL 5 /* trigger on falling edge */
56 #define FLAG_TRIG_RISE 6 /* trigger on rising edge */
57 #define FLAG_ACTIVE_LOW 7 /* sysfs value has active low */
59 #define PDESC_ID_SHIFT 16 /* add new flags before this one */
61 #define GPIO_FLAGS_MASK ((1 << PDESC_ID_SHIFT) - 1)
62 #define GPIO_TRIGGER_MASK (BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE))
64 #ifdef CONFIG_DEBUG_FS
68 static struct gpio_desc gpio_desc
[ARCH_NR_GPIOS
];
70 #ifdef CONFIG_GPIO_SYSFS
72 struct work_struct work
;
73 struct sysfs_dirent
*value_sd
;
76 static struct idr pdesc_idr
;
79 static inline void desc_set_label(struct gpio_desc
*d
, const char *label
)
81 #ifdef CONFIG_DEBUG_FS
86 /* Warn when drivers omit gpio_request() calls -- legal but ill-advised
87 * when setting direction, and otherwise illegal. Until board setup code
88 * and drivers use explicit requests everywhere (which won't happen when
89 * those calls have no teeth) we can't avoid autorequesting. This nag
90 * message should motivate switching to explicit requests... so should
91 * the weaker cleanup after faults, compared to gpio_request().
93 * NOTE: the autorequest mechanism is going away; at this point it's
94 * only "legal" in the sense that (old) code using it won't break yet,
95 * but instead only triggers a WARN() stack dump.
97 static int gpio_ensure_requested(struct gpio_desc
*desc
, unsigned offset
)
99 const struct gpio_chip
*chip
= desc
->chip
;
100 const int gpio
= chip
->base
+ offset
;
102 if (WARN(test_and_set_bit(FLAG_REQUESTED
, &desc
->flags
) == 0,
103 "autorequest GPIO-%d\n", gpio
)) {
104 if (!try_module_get(chip
->owner
)) {
105 pr_err("GPIO-%d: module can't be gotten \n", gpio
);
106 clear_bit(FLAG_REQUESTED
, &desc
->flags
);
110 desc_set_label(desc
, "[auto]");
111 /* caller must chip->request() w/o spinlock */
118 /* caller holds gpio_lock *OR* gpio is marked as requested */
119 static inline struct gpio_chip
*gpio_to_chip(unsigned gpio
)
121 return gpio_desc
[gpio
].chip
;
124 /* dynamic allocation of GPIOs, e.g. on a hotplugged device */
125 static int gpiochip_find_base(int ngpio
)
131 for (i
= ARCH_NR_GPIOS
- 1; i
>= 0 ; i
--) {
132 struct gpio_desc
*desc
= &gpio_desc
[i
];
133 struct gpio_chip
*chip
= desc
->chip
;
135 if (!chip
&& !test_bit(FLAG_RESERVED
, &desc
->flags
)) {
137 if (spare
== ngpio
) {
144 i
-= chip
->ngpio
- 1;
148 if (gpio_is_valid(base
))
149 pr_debug("%s: found new base at %d\n", __func__
, base
);
154 * gpiochip_reserve() - reserve range of gpios to use with platform code only
155 * @start: starting gpio number
156 * @ngpio: number of gpios to reserve
157 * Context: platform init, potentially before irqs or kmalloc will work
159 * Returns a negative errno if any gpio within the range is already reserved
160 * or registered, else returns zero as a success code. Use this function
161 * to mark a range of gpios as unavailable for dynamic gpio number allocation,
162 * for example because its driver support is not yet loaded.
164 int __init
gpiochip_reserve(int start
, int ngpio
)
170 if (!gpio_is_valid(start
) || !gpio_is_valid(start
+ ngpio
- 1))
173 spin_lock_irqsave(&gpio_lock
, flags
);
175 for (i
= start
; i
< start
+ ngpio
; i
++) {
176 struct gpio_desc
*desc
= &gpio_desc
[i
];
178 if (desc
->chip
|| test_bit(FLAG_RESERVED
, &desc
->flags
)) {
183 set_bit(FLAG_RESERVED
, &desc
->flags
);
186 pr_debug("%s: reserved gpios from %d to %d\n",
187 __func__
, start
, start
+ ngpio
- 1);
189 spin_unlock_irqrestore(&gpio_lock
, flags
);
194 #ifdef CONFIG_GPIO_SYSFS
196 /* lock protects against unexport_gpio() being called while
197 * sysfs files are active.
199 static DEFINE_MUTEX(sysfs_lock
);
202 * /sys/class/gpio/gpioN... only for GPIOs that are exported
204 * * MAY BE OMITTED if kernel won't allow direction changes
205 * * is read/write as "in" or "out"
206 * * may also be written as "high" or "low", initializing
207 * output value as specified ("out" implies "low")
209 * * always readable, subject to hardware behavior
210 * * may be writable, as zero/nonzero
212 * * configures behavior of poll(2) on /value
213 * * available only if pin can generate IRQs on input
214 * * is read/write as "none", "falling", "rising", or "both"
216 * * configures polarity of /value
217 * * is read/write as zero/nonzero
218 * * also affects existing and subsequent "falling" and "rising"
219 * /edge configuration
222 static ssize_t
gpio_direction_show(struct device
*dev
,
223 struct device_attribute
*attr
, char *buf
)
225 const struct gpio_desc
*desc
= dev_get_drvdata(dev
);
228 mutex_lock(&sysfs_lock
);
230 if (!test_bit(FLAG_EXPORT
, &desc
->flags
))
233 status
= sprintf(buf
, "%s\n",
234 test_bit(FLAG_IS_OUT
, &desc
->flags
)
237 mutex_unlock(&sysfs_lock
);
241 static ssize_t
gpio_direction_store(struct device
*dev
,
242 struct device_attribute
*attr
, const char *buf
, size_t size
)
244 const struct gpio_desc
*desc
= dev_get_drvdata(dev
);
245 unsigned gpio
= desc
- gpio_desc
;
248 mutex_lock(&sysfs_lock
);
250 if (!test_bit(FLAG_EXPORT
, &desc
->flags
))
252 else if (sysfs_streq(buf
, "high"))
253 status
= gpio_direction_output(gpio
, 1);
254 else if (sysfs_streq(buf
, "out") || sysfs_streq(buf
, "low"))
255 status
= gpio_direction_output(gpio
, 0);
256 else if (sysfs_streq(buf
, "in"))
257 status
= gpio_direction_input(gpio
);
261 mutex_unlock(&sysfs_lock
);
262 return status
? : size
;
265 static /* const */ DEVICE_ATTR(direction
, 0644,
266 gpio_direction_show
, gpio_direction_store
);
268 static ssize_t
gpio_value_show(struct device
*dev
,
269 struct device_attribute
*attr
, char *buf
)
271 const struct gpio_desc
*desc
= dev_get_drvdata(dev
);
272 unsigned gpio
= desc
- gpio_desc
;
275 mutex_lock(&sysfs_lock
);
277 if (!test_bit(FLAG_EXPORT
, &desc
->flags
)) {
282 value
= !!gpio_get_value_cansleep(gpio
);
283 if (test_bit(FLAG_ACTIVE_LOW
, &desc
->flags
))
286 status
= sprintf(buf
, "%d\n", value
);
289 mutex_unlock(&sysfs_lock
);
293 static ssize_t
gpio_value_store(struct device
*dev
,
294 struct device_attribute
*attr
, const char *buf
, size_t size
)
296 const struct gpio_desc
*desc
= dev_get_drvdata(dev
);
297 unsigned gpio
= desc
- gpio_desc
;
300 mutex_lock(&sysfs_lock
);
302 if (!test_bit(FLAG_EXPORT
, &desc
->flags
))
304 else if (!test_bit(FLAG_IS_OUT
, &desc
->flags
))
309 status
= strict_strtol(buf
, 0, &value
);
311 if (test_bit(FLAG_ACTIVE_LOW
, &desc
->flags
))
313 gpio_set_value_cansleep(gpio
, value
!= 0);
318 mutex_unlock(&sysfs_lock
);
322 static const DEVICE_ATTR(value
, 0644,
323 gpio_value_show
, gpio_value_store
);
325 static irqreturn_t
gpio_sysfs_irq(int irq
, void *priv
)
327 struct work_struct
*work
= priv
;
333 static void gpio_notify_sysfs(struct work_struct
*work
)
335 struct poll_desc
*pdesc
;
337 pdesc
= container_of(work
, struct poll_desc
, work
);
338 sysfs_notify_dirent(pdesc
->value_sd
);
341 static int gpio_setup_irq(struct gpio_desc
*desc
, struct device
*dev
,
342 unsigned long gpio_flags
)
344 struct poll_desc
*pdesc
;
345 unsigned long irq_flags
;
348 if ((desc
->flags
& GPIO_TRIGGER_MASK
) == gpio_flags
)
351 irq
= gpio_to_irq(desc
- gpio_desc
);
355 id
= desc
->flags
>> PDESC_ID_SHIFT
;
356 pdesc
= idr_find(&pdesc_idr
, id
);
358 free_irq(irq
, &pdesc
->work
);
359 cancel_work_sync(&pdesc
->work
);
362 desc
->flags
&= ~GPIO_TRIGGER_MASK
;
369 irq_flags
= IRQF_SHARED
;
370 if (test_bit(FLAG_TRIG_FALL
, &gpio_flags
))
371 irq_flags
|= test_bit(FLAG_ACTIVE_LOW
, &desc
->flags
) ?
372 IRQF_TRIGGER_RISING
: IRQF_TRIGGER_FALLING
;
373 if (test_bit(FLAG_TRIG_RISE
, &gpio_flags
))
374 irq_flags
|= test_bit(FLAG_ACTIVE_LOW
, &desc
->flags
) ?
375 IRQF_TRIGGER_FALLING
: IRQF_TRIGGER_RISING
;
378 pdesc
= kmalloc(sizeof(*pdesc
), GFP_KERNEL
);
386 if (idr_pre_get(&pdesc_idr
, GFP_KERNEL
))
387 ret
= idr_get_new_above(&pdesc_idr
,
389 } while (ret
== -EAGAIN
);
394 desc
->flags
&= GPIO_FLAGS_MASK
;
395 desc
->flags
|= (unsigned long)id
<< PDESC_ID_SHIFT
;
397 if (desc
->flags
>> PDESC_ID_SHIFT
!= id
) {
402 pdesc
->value_sd
= sysfs_get_dirent(dev
->kobj
.sd
, NULL
, "value");
403 if (!pdesc
->value_sd
) {
407 INIT_WORK(&pdesc
->work
, gpio_notify_sysfs
);
410 ret
= request_irq(irq
, gpio_sysfs_irq
, irq_flags
,
411 "gpiolib", &pdesc
->work
);
415 desc
->flags
|= gpio_flags
;
420 sysfs_put(pdesc
->value_sd
);
422 idr_remove(&pdesc_idr
, id
);
423 desc
->flags
&= GPIO_FLAGS_MASK
;
430 static const struct {
433 } trigger_types
[] = {
435 { "falling", BIT(FLAG_TRIG_FALL
) },
436 { "rising", BIT(FLAG_TRIG_RISE
) },
437 { "both", BIT(FLAG_TRIG_FALL
) | BIT(FLAG_TRIG_RISE
) },
440 static ssize_t
gpio_edge_show(struct device
*dev
,
441 struct device_attribute
*attr
, char *buf
)
443 const struct gpio_desc
*desc
= dev_get_drvdata(dev
);
446 mutex_lock(&sysfs_lock
);
448 if (!test_bit(FLAG_EXPORT
, &desc
->flags
))
454 for (i
= 0; i
< ARRAY_SIZE(trigger_types
); i
++)
455 if ((desc
->flags
& GPIO_TRIGGER_MASK
)
456 == trigger_types
[i
].flags
) {
457 status
= sprintf(buf
, "%s\n",
458 trigger_types
[i
].name
);
463 mutex_unlock(&sysfs_lock
);
467 static ssize_t
gpio_edge_store(struct device
*dev
,
468 struct device_attribute
*attr
, const char *buf
, size_t size
)
470 struct gpio_desc
*desc
= dev_get_drvdata(dev
);
474 for (i
= 0; i
< ARRAY_SIZE(trigger_types
); i
++)
475 if (sysfs_streq(trigger_types
[i
].name
, buf
))
480 mutex_lock(&sysfs_lock
);
482 if (!test_bit(FLAG_EXPORT
, &desc
->flags
))
485 status
= gpio_setup_irq(desc
, dev
, trigger_types
[i
].flags
);
490 mutex_unlock(&sysfs_lock
);
495 static DEVICE_ATTR(edge
, 0644, gpio_edge_show
, gpio_edge_store
);
497 static int sysfs_set_active_low(struct gpio_desc
*desc
, struct device
*dev
,
502 if (!!test_bit(FLAG_ACTIVE_LOW
, &desc
->flags
) == !!value
)
506 set_bit(FLAG_ACTIVE_LOW
, &desc
->flags
);
508 clear_bit(FLAG_ACTIVE_LOW
, &desc
->flags
);
510 /* reconfigure poll(2) support if enabled on one edge only */
511 if (dev
!= NULL
&& (!!test_bit(FLAG_TRIG_RISE
, &desc
->flags
) ^
512 !!test_bit(FLAG_TRIG_FALL
, &desc
->flags
))) {
513 unsigned long trigger_flags
= desc
->flags
& GPIO_TRIGGER_MASK
;
515 gpio_setup_irq(desc
, dev
, 0);
516 status
= gpio_setup_irq(desc
, dev
, trigger_flags
);
522 static ssize_t
gpio_active_low_show(struct device
*dev
,
523 struct device_attribute
*attr
, char *buf
)
525 const struct gpio_desc
*desc
= dev_get_drvdata(dev
);
528 mutex_lock(&sysfs_lock
);
530 if (!test_bit(FLAG_EXPORT
, &desc
->flags
))
533 status
= sprintf(buf
, "%d\n",
534 !!test_bit(FLAG_ACTIVE_LOW
, &desc
->flags
));
536 mutex_unlock(&sysfs_lock
);
541 static ssize_t
gpio_active_low_store(struct device
*dev
,
542 struct device_attribute
*attr
, const char *buf
, size_t size
)
544 struct gpio_desc
*desc
= dev_get_drvdata(dev
);
547 mutex_lock(&sysfs_lock
);
549 if (!test_bit(FLAG_EXPORT
, &desc
->flags
)) {
554 status
= strict_strtol(buf
, 0, &value
);
556 status
= sysfs_set_active_low(desc
, dev
, value
!= 0);
559 mutex_unlock(&sysfs_lock
);
561 return status
? : size
;
564 static const DEVICE_ATTR(active_low
, 0644,
565 gpio_active_low_show
, gpio_active_low_store
);
567 static const struct attribute
*gpio_attrs
[] = {
568 &dev_attr_value
.attr
,
569 &dev_attr_active_low
.attr
,
573 static const struct attribute_group gpio_attr_group
= {
574 .attrs
= (struct attribute
**) gpio_attrs
,
578 * /sys/class/gpio/gpiochipN/
579 * /base ... matching gpio_chip.base (N)
580 * /label ... matching gpio_chip.label
581 * /ngpio ... matching gpio_chip.ngpio
584 static ssize_t
chip_base_show(struct device
*dev
,
585 struct device_attribute
*attr
, char *buf
)
587 const struct gpio_chip
*chip
= dev_get_drvdata(dev
);
589 return sprintf(buf
, "%d\n", chip
->base
);
591 static DEVICE_ATTR(base
, 0444, chip_base_show
, NULL
);
593 static ssize_t
chip_label_show(struct device
*dev
,
594 struct device_attribute
*attr
, char *buf
)
596 const struct gpio_chip
*chip
= dev_get_drvdata(dev
);
598 return sprintf(buf
, "%s\n", chip
->label
? : "");
600 static DEVICE_ATTR(label
, 0444, chip_label_show
, NULL
);
602 static ssize_t
chip_ngpio_show(struct device
*dev
,
603 struct device_attribute
*attr
, char *buf
)
605 const struct gpio_chip
*chip
= dev_get_drvdata(dev
);
607 return sprintf(buf
, "%u\n", chip
->ngpio
);
609 static DEVICE_ATTR(ngpio
, 0444, chip_ngpio_show
, NULL
);
611 static const struct attribute
*gpiochip_attrs
[] = {
613 &dev_attr_label
.attr
,
614 &dev_attr_ngpio
.attr
,
618 static const struct attribute_group gpiochip_attr_group
= {
619 .attrs
= (struct attribute
**) gpiochip_attrs
,
623 * /sys/class/gpio/export ... write-only
624 * integer N ... number of GPIO to export (full access)
625 * /sys/class/gpio/unexport ... write-only
626 * integer N ... number of GPIO to unexport
628 static ssize_t
export_store(struct class *class,
629 struct class_attribute
*attr
,
630 const char *buf
, size_t len
)
635 status
= strict_strtol(buf
, 0, &gpio
);
639 /* No extra locking here; FLAG_SYSFS just signifies that the
640 * request and export were done by on behalf of userspace, so
641 * they may be undone on its behalf too.
644 status
= gpio_request(gpio
, "sysfs");
648 status
= gpio_export(gpio
, true);
652 set_bit(FLAG_SYSFS
, &gpio_desc
[gpio
].flags
);
656 pr_debug("%s: status %d\n", __func__
, status
);
657 return status
? : len
;
660 static ssize_t
unexport_store(struct class *class,
661 struct class_attribute
*attr
,
662 const char *buf
, size_t len
)
667 status
= strict_strtol(buf
, 0, &gpio
);
673 /* reject bogus commands (gpio_unexport ignores them) */
674 if (!gpio_is_valid(gpio
))
677 /* No extra locking here; FLAG_SYSFS just signifies that the
678 * request and export were done by on behalf of userspace, so
679 * they may be undone on its behalf too.
681 if (test_and_clear_bit(FLAG_SYSFS
, &gpio_desc
[gpio
].flags
)) {
687 pr_debug("%s: status %d\n", __func__
, status
);
688 return status
? : len
;
691 static struct class_attribute gpio_class_attrs
[] = {
692 __ATTR(export
, 0200, NULL
, export_store
),
693 __ATTR(unexport
, 0200, NULL
, unexport_store
),
697 static struct class gpio_class
= {
699 .owner
= THIS_MODULE
,
701 .class_attrs
= gpio_class_attrs
,
706 * gpio_export - export a GPIO through sysfs
707 * @gpio: gpio to make available, already requested
708 * @direction_may_change: true if userspace may change gpio direction
709 * Context: arch_initcall or later
711 * When drivers want to make a GPIO accessible to userspace after they
712 * have requested it -- perhaps while debugging, or as part of their
713 * public interface -- they may use this routine. If the GPIO can
714 * change direction (some can't) and the caller allows it, userspace
715 * will see "direction" sysfs attribute which may be used to change
716 * the gpio's direction. A "value" attribute will always be provided.
718 * Returns zero on success, else an error.
720 int gpio_export(unsigned gpio
, bool direction_may_change
)
723 struct gpio_desc
*desc
;
724 int status
= -EINVAL
;
727 /* can't export until sysfs is available ... */
729 pr_debug("%s: called too early!\n", __func__
);
733 if (!gpio_is_valid(gpio
))
736 mutex_lock(&sysfs_lock
);
738 spin_lock_irqsave(&gpio_lock
, flags
);
739 desc
= &gpio_desc
[gpio
];
740 if (test_bit(FLAG_REQUESTED
, &desc
->flags
)
741 && !test_bit(FLAG_EXPORT
, &desc
->flags
)) {
743 if (!desc
->chip
->direction_input
744 || !desc
->chip
->direction_output
)
745 direction_may_change
= false;
747 spin_unlock_irqrestore(&gpio_lock
, flags
);
749 if (desc
->chip
->names
&& desc
->chip
->names
[gpio
- desc
->chip
->base
])
750 ioname
= desc
->chip
->names
[gpio
- desc
->chip
->base
];
755 dev
= device_create(&gpio_class
, desc
->chip
->dev
, MKDEV(0, 0),
756 desc
, ioname
? ioname
: "gpio%d", gpio
);
758 status
= sysfs_create_group(&dev
->kobj
,
761 if (!status
&& direction_may_change
)
762 status
= device_create_file(dev
,
763 &dev_attr_direction
);
765 if (!status
&& gpio_to_irq(gpio
) >= 0
766 && (direction_may_change
767 || !test_bit(FLAG_IS_OUT
,
769 status
= device_create_file(dev
,
773 device_unregister(dev
);
775 status
= PTR_ERR(dev
);
777 set_bit(FLAG_EXPORT
, &desc
->flags
);
780 mutex_unlock(&sysfs_lock
);
784 pr_debug("%s: gpio%d status %d\n", __func__
, gpio
, status
);
788 EXPORT_SYMBOL_GPL(gpio_export
);
790 static int match_export(struct device
*dev
, void *data
)
792 return dev_get_drvdata(dev
) == data
;
796 * gpio_export_link - create a sysfs link to an exported GPIO node
797 * @dev: device under which to create symlink
798 * @name: name of the symlink
799 * @gpio: gpio to create symlink to, already exported
801 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
802 * node. Caller is responsible for unlinking.
804 * Returns zero on success, else an error.
806 int gpio_export_link(struct device
*dev
, const char *name
, unsigned gpio
)
808 struct gpio_desc
*desc
;
809 int status
= -EINVAL
;
811 if (!gpio_is_valid(gpio
))
814 mutex_lock(&sysfs_lock
);
816 desc
= &gpio_desc
[gpio
];
818 if (test_bit(FLAG_EXPORT
, &desc
->flags
)) {
821 tdev
= class_find_device(&gpio_class
, NULL
, desc
, match_export
);
823 status
= sysfs_create_link(&dev
->kobj
, &tdev
->kobj
,
830 mutex_unlock(&sysfs_lock
);
834 pr_debug("%s: gpio%d status %d\n", __func__
, gpio
, status
);
838 EXPORT_SYMBOL_GPL(gpio_export_link
);
842 * gpio_sysfs_set_active_low - set the polarity of gpio sysfs value
843 * @gpio: gpio to change
844 * @value: non-zero to use active low, i.e. inverted values
846 * Set the polarity of /sys/class/gpio/gpioN/value sysfs attribute.
847 * The GPIO does not have to be exported yet. If poll(2) support has
848 * been enabled for either rising or falling edge, it will be
849 * reconfigured to follow the new polarity.
851 * Returns zero on success, else an error.
853 int gpio_sysfs_set_active_low(unsigned gpio
, int value
)
855 struct gpio_desc
*desc
;
856 struct device
*dev
= NULL
;
857 int status
= -EINVAL
;
859 if (!gpio_is_valid(gpio
))
862 mutex_lock(&sysfs_lock
);
864 desc
= &gpio_desc
[gpio
];
866 if (test_bit(FLAG_EXPORT
, &desc
->flags
)) {
867 dev
= class_find_device(&gpio_class
, NULL
, desc
, match_export
);
874 status
= sysfs_set_active_low(desc
, dev
, value
);
877 mutex_unlock(&sysfs_lock
);
881 pr_debug("%s: gpio%d status %d\n", __func__
, gpio
, status
);
885 EXPORT_SYMBOL_GPL(gpio_sysfs_set_active_low
);
888 * gpio_unexport - reverse effect of gpio_export()
889 * @gpio: gpio to make unavailable
891 * This is implicit on gpio_free().
893 void gpio_unexport(unsigned gpio
)
895 struct gpio_desc
*desc
;
896 int status
= -EINVAL
;
898 if (!gpio_is_valid(gpio
))
901 mutex_lock(&sysfs_lock
);
903 desc
= &gpio_desc
[gpio
];
905 if (test_bit(FLAG_EXPORT
, &desc
->flags
)) {
906 struct device
*dev
= NULL
;
908 dev
= class_find_device(&gpio_class
, NULL
, desc
, match_export
);
910 gpio_setup_irq(desc
, dev
, 0);
911 clear_bit(FLAG_EXPORT
, &desc
->flags
);
913 device_unregister(dev
);
919 mutex_unlock(&sysfs_lock
);
922 pr_debug("%s: gpio%d status %d\n", __func__
, gpio
, status
);
924 EXPORT_SYMBOL_GPL(gpio_unexport
);
926 static int gpiochip_export(struct gpio_chip
*chip
)
931 /* Many systems register gpio chips for SOC support very early,
932 * before driver model support is available. In those cases we
933 * export this later, in gpiolib_sysfs_init() ... here we just
934 * verify that _some_ field of gpio_class got initialized.
939 /* use chip->base for the ID; it's already known to be unique */
940 mutex_lock(&sysfs_lock
);
941 dev
= device_create(&gpio_class
, chip
->dev
, MKDEV(0, 0), chip
,
942 "gpiochip%d", chip
->base
);
944 status
= sysfs_create_group(&dev
->kobj
,
945 &gpiochip_attr_group
);
947 status
= PTR_ERR(dev
);
948 chip
->exported
= (status
== 0);
949 mutex_unlock(&sysfs_lock
);
955 spin_lock_irqsave(&gpio_lock
, flags
);
957 while (gpio_desc
[gpio
].chip
== chip
)
958 gpio_desc
[gpio
++].chip
= NULL
;
959 spin_unlock_irqrestore(&gpio_lock
, flags
);
961 pr_debug("%s: chip %s status %d\n", __func__
,
962 chip
->label
, status
);
968 static void gpiochip_unexport(struct gpio_chip
*chip
)
973 mutex_lock(&sysfs_lock
);
974 dev
= class_find_device(&gpio_class
, NULL
, chip
, match_export
);
977 device_unregister(dev
);
982 mutex_unlock(&sysfs_lock
);
985 pr_debug("%s: chip %s status %d\n", __func__
,
986 chip
->label
, status
);
989 static int __init
gpiolib_sysfs_init(void)
995 idr_init(&pdesc_idr
);
997 status
= class_register(&gpio_class
);
1001 /* Scan and register the gpio_chips which registered very
1002 * early (e.g. before the class_register above was called).
1004 * We run before arch_initcall() so chip->dev nodes can have
1005 * registered, and so arch_initcall() can always gpio_export().
1007 spin_lock_irqsave(&gpio_lock
, flags
);
1008 for (gpio
= 0; gpio
< ARCH_NR_GPIOS
; gpio
++) {
1009 struct gpio_chip
*chip
;
1011 chip
= gpio_desc
[gpio
].chip
;
1012 if (!chip
|| chip
->exported
)
1015 spin_unlock_irqrestore(&gpio_lock
, flags
);
1016 status
= gpiochip_export(chip
);
1017 spin_lock_irqsave(&gpio_lock
, flags
);
1019 spin_unlock_irqrestore(&gpio_lock
, flags
);
1024 postcore_initcall(gpiolib_sysfs_init
);
1027 static inline int gpiochip_export(struct gpio_chip
*chip
)
1032 static inline void gpiochip_unexport(struct gpio_chip
*chip
)
1036 #endif /* CONFIG_GPIO_SYSFS */
1039 * gpiochip_add() - register a gpio_chip
1040 * @chip: the chip to register, with chip->base initialized
1041 * Context: potentially before irqs or kmalloc will work
1043 * Returns a negative errno if the chip can't be registered, such as
1044 * because the chip->base is invalid or already associated with a
1045 * different chip. Otherwise it returns zero as a success code.
1047 * When gpiochip_add() is called very early during boot, so that GPIOs
1048 * can be freely used, the chip->dev device must be registered before
1049 * the gpio framework's arch_initcall(). Otherwise sysfs initialization
1050 * for GPIOs will fail rudely.
1052 * If chip->base is negative, this requests dynamic assignment of
1053 * a range of valid GPIOs.
1055 int gpiochip_add(struct gpio_chip
*chip
)
1057 unsigned long flags
;
1060 int base
= chip
->base
;
1062 if ((!gpio_is_valid(base
) || !gpio_is_valid(base
+ chip
->ngpio
- 1))
1068 spin_lock_irqsave(&gpio_lock
, flags
);
1071 base
= gpiochip_find_base(chip
->ngpio
);
1079 /* these GPIO numbers must not be managed by another gpio_chip */
1080 for (id
= base
; id
< base
+ chip
->ngpio
; id
++) {
1081 if (gpio_desc
[id
].chip
!= NULL
) {
1087 for (id
= base
; id
< base
+ chip
->ngpio
; id
++) {
1088 gpio_desc
[id
].chip
= chip
;
1090 /* REVISIT: most hardware initializes GPIOs as
1091 * inputs (often with pullups enabled) so power
1092 * usage is minimized. Linux code should set the
1093 * gpio direction first thing; but until it does,
1094 * we may expose the wrong direction in sysfs.
1096 gpio_desc
[id
].flags
= !chip
->direction_input
1097 ? (1 << FLAG_IS_OUT
)
1103 spin_unlock_irqrestore(&gpio_lock
, flags
);
1105 status
= gpiochip_export(chip
);
1107 /* failures here can mean systems won't boot... */
1109 pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n",
1110 chip
->base
, chip
->base
+ chip
->ngpio
- 1,
1111 chip
->label
? : "generic");
1114 EXPORT_SYMBOL_GPL(gpiochip_add
);
1117 * gpiochip_remove() - unregister a gpio_chip
1118 * @chip: the chip to unregister
1120 * A gpio_chip with any GPIOs still requested may not be removed.
1122 int gpiochip_remove(struct gpio_chip
*chip
)
1124 unsigned long flags
;
1128 spin_lock_irqsave(&gpio_lock
, flags
);
1130 for (id
= chip
->base
; id
< chip
->base
+ chip
->ngpio
; id
++) {
1131 if (test_bit(FLAG_REQUESTED
, &gpio_desc
[id
].flags
)) {
1137 for (id
= chip
->base
; id
< chip
->base
+ chip
->ngpio
; id
++)
1138 gpio_desc
[id
].chip
= NULL
;
1141 spin_unlock_irqrestore(&gpio_lock
, flags
);
1144 gpiochip_unexport(chip
);
1148 EXPORT_SYMBOL_GPL(gpiochip_remove
);
1151 /* These "optional" allocation calls help prevent drivers from stomping
1152 * on each other, and help provide better diagnostics in debugfs.
1153 * They're called even less than the "set direction" calls.
1155 int gpio_request(unsigned gpio
, const char *label
)
1157 struct gpio_desc
*desc
;
1158 struct gpio_chip
*chip
;
1159 int status
= -EINVAL
;
1160 unsigned long flags
;
1162 spin_lock_irqsave(&gpio_lock
, flags
);
1164 if (!gpio_is_valid(gpio
))
1166 desc
= &gpio_desc
[gpio
];
1171 if (!try_module_get(chip
->owner
))
1174 /* NOTE: gpio_request() can be called in early boot,
1175 * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
1178 if (test_and_set_bit(FLAG_REQUESTED
, &desc
->flags
) == 0) {
1179 desc_set_label(desc
, label
? : "?");
1183 module_put(chip
->owner
);
1187 if (chip
->request
) {
1188 /* chip->request may sleep */
1189 spin_unlock_irqrestore(&gpio_lock
, flags
);
1190 status
= chip
->request(chip
, gpio
- chip
->base
);
1191 spin_lock_irqsave(&gpio_lock
, flags
);
1194 desc_set_label(desc
, NULL
);
1195 module_put(chip
->owner
);
1196 clear_bit(FLAG_REQUESTED
, &desc
->flags
);
1202 pr_debug("gpio_request: gpio-%d (%s) status %d\n",
1203 gpio
, label
? : "?", status
);
1204 spin_unlock_irqrestore(&gpio_lock
, flags
);
1207 EXPORT_SYMBOL_GPL(gpio_request
);
1209 void gpio_free(unsigned gpio
)
1211 unsigned long flags
;
1212 struct gpio_desc
*desc
;
1213 struct gpio_chip
*chip
;
1217 if (!gpio_is_valid(gpio
)) {
1218 WARN_ON(extra_checks
);
1222 gpio_unexport(gpio
);
1224 spin_lock_irqsave(&gpio_lock
, flags
);
1226 desc
= &gpio_desc
[gpio
];
1228 if (chip
&& test_bit(FLAG_REQUESTED
, &desc
->flags
)) {
1230 spin_unlock_irqrestore(&gpio_lock
, flags
);
1231 might_sleep_if(extra_checks
&& chip
->can_sleep
);
1232 chip
->free(chip
, gpio
- chip
->base
);
1233 spin_lock_irqsave(&gpio_lock
, flags
);
1235 desc_set_label(desc
, NULL
);
1236 module_put(desc
->chip
->owner
);
1237 clear_bit(FLAG_ACTIVE_LOW
, &desc
->flags
);
1238 clear_bit(FLAG_REQUESTED
, &desc
->flags
);
1240 WARN_ON(extra_checks
);
1242 spin_unlock_irqrestore(&gpio_lock
, flags
);
1244 EXPORT_SYMBOL_GPL(gpio_free
);
1247 * gpio_request_one - request a single GPIO with initial configuration
1248 * @gpio: the GPIO number
1249 * @flags: GPIO configuration as specified by GPIOF_*
1250 * @label: a literal description string of this GPIO
1252 int gpio_request_one(unsigned gpio
, unsigned long flags
, const char *label
)
1256 err
= gpio_request(gpio
, label
);
1260 if (flags
& GPIOF_DIR_IN
)
1261 err
= gpio_direction_input(gpio
);
1263 err
= gpio_direction_output(gpio
,
1264 (flags
& GPIOF_INIT_HIGH
) ? 1 : 0);
1268 EXPORT_SYMBOL_GPL(gpio_request_one
);
1271 * gpio_request_array - request multiple GPIOs in a single call
1272 * @array: array of the 'struct gpio'
1273 * @num: how many GPIOs in the array
1275 int gpio_request_array(struct gpio
*array
, size_t num
)
1279 for (i
= 0; i
< num
; i
++, array
++) {
1280 err
= gpio_request_one(array
->gpio
, array
->flags
, array
->label
);
1288 gpio_free((--array
)->gpio
);
1291 EXPORT_SYMBOL_GPL(gpio_request_array
);
1294 * gpio_free_array - release multiple GPIOs in a single call
1295 * @array: array of the 'struct gpio'
1296 * @num: how many GPIOs in the array
1298 void gpio_free_array(struct gpio
*array
, size_t num
)
1301 gpio_free((array
++)->gpio
);
1303 EXPORT_SYMBOL_GPL(gpio_free_array
);
1306 * gpiochip_is_requested - return string iff signal was requested
1307 * @chip: controller managing the signal
1308 * @offset: of signal within controller's 0..(ngpio - 1) range
1310 * Returns NULL if the GPIO is not currently requested, else a string.
1311 * If debugfs support is enabled, the string returned is the label passed
1312 * to gpio_request(); otherwise it is a meaningless constant.
1314 * This function is for use by GPIO controller drivers. The label can
1315 * help with diagnostics, and knowing that the signal is used as a GPIO
1316 * can help avoid accidentally multiplexing it to another controller.
1318 const char *gpiochip_is_requested(struct gpio_chip
*chip
, unsigned offset
)
1320 unsigned gpio
= chip
->base
+ offset
;
1322 if (!gpio_is_valid(gpio
) || gpio_desc
[gpio
].chip
!= chip
)
1324 if (test_bit(FLAG_REQUESTED
, &gpio_desc
[gpio
].flags
) == 0)
1326 #ifdef CONFIG_DEBUG_FS
1327 return gpio_desc
[gpio
].label
;
1332 EXPORT_SYMBOL_GPL(gpiochip_is_requested
);
1335 /* Drivers MUST set GPIO direction before making get/set calls. In
1336 * some cases this is done in early boot, before IRQs are enabled.
1338 * As a rule these aren't called more than once (except for drivers
1339 * using the open-drain emulation idiom) so these are natural places
1340 * to accumulate extra debugging checks. Note that we can't (yet)
1341 * rely on gpio_request() having been called beforehand.
1344 int gpio_direction_input(unsigned gpio
)
1346 unsigned long flags
;
1347 struct gpio_chip
*chip
;
1348 struct gpio_desc
*desc
= &gpio_desc
[gpio
];
1349 int status
= -EINVAL
;
1351 spin_lock_irqsave(&gpio_lock
, flags
);
1353 if (!gpio_is_valid(gpio
))
1356 if (!chip
|| !chip
->get
|| !chip
->direction_input
)
1359 if (gpio
>= chip
->ngpio
)
1361 status
= gpio_ensure_requested(desc
, gpio
);
1365 /* now we know the gpio is valid and chip won't vanish */
1367 spin_unlock_irqrestore(&gpio_lock
, flags
);
1369 might_sleep_if(extra_checks
&& chip
->can_sleep
);
1372 status
= chip
->request(chip
, gpio
);
1374 pr_debug("GPIO-%d: chip request fail, %d\n",
1375 chip
->base
+ gpio
, status
);
1376 /* and it's not available to anyone else ...
1377 * gpio_request() is the fully clean solution.
1383 status
= chip
->direction_input(chip
, gpio
);
1385 clear_bit(FLAG_IS_OUT
, &desc
->flags
);
1389 spin_unlock_irqrestore(&gpio_lock
, flags
);
1391 pr_debug("%s: gpio-%d status %d\n",
1392 __func__
, gpio
, status
);
1395 EXPORT_SYMBOL_GPL(gpio_direction_input
);
1397 int gpio_direction_output(unsigned gpio
, int value
)
1399 unsigned long flags
;
1400 struct gpio_chip
*chip
;
1401 struct gpio_desc
*desc
= &gpio_desc
[gpio
];
1402 int status
= -EINVAL
;
1404 spin_lock_irqsave(&gpio_lock
, flags
);
1406 if (!gpio_is_valid(gpio
))
1409 if (!chip
|| !chip
->set
|| !chip
->direction_output
)
1412 if (gpio
>= chip
->ngpio
)
1414 status
= gpio_ensure_requested(desc
, gpio
);
1418 /* now we know the gpio is valid and chip won't vanish */
1420 spin_unlock_irqrestore(&gpio_lock
, flags
);
1422 might_sleep_if(extra_checks
&& chip
->can_sleep
);
1425 status
= chip
->request(chip
, gpio
);
1427 pr_debug("GPIO-%d: chip request fail, %d\n",
1428 chip
->base
+ gpio
, status
);
1429 /* and it's not available to anyone else ...
1430 * gpio_request() is the fully clean solution.
1436 status
= chip
->direction_output(chip
, gpio
, value
);
1438 set_bit(FLAG_IS_OUT
, &desc
->flags
);
1442 spin_unlock_irqrestore(&gpio_lock
, flags
);
1444 pr_debug("%s: gpio-%d status %d\n",
1445 __func__
, gpio
, status
);
1448 EXPORT_SYMBOL_GPL(gpio_direction_output
);
1451 /* I/O calls are only valid after configuration completed; the relevant
1452 * "is this a valid GPIO" error checks should already have been done.
1454 * "Get" operations are often inlinable as reading a pin value register,
1455 * and masking the relevant bit in that register.
1457 * When "set" operations are inlinable, they involve writing that mask to
1458 * one register to set a low value, or a different register to set it high.
1459 * Otherwise locking is needed, so there may be little value to inlining.
1461 *------------------------------------------------------------------------
1463 * IMPORTANT!!! The hot paths -- get/set value -- assume that callers
1464 * have requested the GPIO. That can include implicit requesting by
1465 * a direction setting call. Marking a gpio as requested locks its chip
1466 * in memory, guaranteeing that these table lookups need no more locking
1467 * and that gpiochip_remove() will fail.
1469 * REVISIT when debugging, consider adding some instrumentation to ensure
1470 * that the GPIO was actually requested.
1474 * __gpio_get_value() - return a gpio's value
1475 * @gpio: gpio whose value will be returned
1478 * This is used directly or indirectly to implement gpio_get_value().
1479 * It returns the zero or nonzero value provided by the associated
1480 * gpio_chip.get() method; or zero if no such method is provided.
1482 int __gpio_get_value(unsigned gpio
)
1484 struct gpio_chip
*chip
;
1486 chip
= gpio_to_chip(gpio
);
1487 WARN_ON(extra_checks
&& chip
->can_sleep
);
1488 return chip
->get
? chip
->get(chip
, gpio
- chip
->base
) : 0;
1490 EXPORT_SYMBOL_GPL(__gpio_get_value
);
1493 * __gpio_set_value() - assign a gpio's value
1494 * @gpio: gpio whose value will be assigned
1495 * @value: value to assign
1498 * This is used directly or indirectly to implement gpio_set_value().
1499 * It invokes the associated gpio_chip.set() method.
1501 void __gpio_set_value(unsigned gpio
, int value
)
1503 struct gpio_chip
*chip
;
1505 chip
= gpio_to_chip(gpio
);
1506 WARN_ON(extra_checks
&& chip
->can_sleep
);
1507 chip
->set(chip
, gpio
- chip
->base
, value
);
1509 EXPORT_SYMBOL_GPL(__gpio_set_value
);
1512 * __gpio_cansleep() - report whether gpio value access will sleep
1513 * @gpio: gpio in question
1516 * This is used directly or indirectly to implement gpio_cansleep(). It
1517 * returns nonzero if access reading or writing the GPIO value can sleep.
1519 int __gpio_cansleep(unsigned gpio
)
1521 struct gpio_chip
*chip
;
1523 /* only call this on GPIOs that are valid! */
1524 chip
= gpio_to_chip(gpio
);
1526 return chip
->can_sleep
;
1528 EXPORT_SYMBOL_GPL(__gpio_cansleep
);
1531 * __gpio_to_irq() - return the IRQ corresponding to a GPIO
1532 * @gpio: gpio whose IRQ will be returned (already requested)
1535 * This is used directly or indirectly to implement gpio_to_irq().
1536 * It returns the number of the IRQ signaled by this (input) GPIO,
1537 * or a negative errno.
1539 int __gpio_to_irq(unsigned gpio
)
1541 struct gpio_chip
*chip
;
1543 chip
= gpio_to_chip(gpio
);
1544 return chip
->to_irq
? chip
->to_irq(chip
, gpio
- chip
->base
) : -ENXIO
;
1546 EXPORT_SYMBOL_GPL(__gpio_to_irq
);
1550 /* There's no value in making it easy to inline GPIO calls that may sleep.
1551 * Common examples include ones connected to I2C or SPI chips.
1554 int gpio_get_value_cansleep(unsigned gpio
)
1556 struct gpio_chip
*chip
;
1558 might_sleep_if(extra_checks
);
1559 chip
= gpio_to_chip(gpio
);
1560 return chip
->get
? chip
->get(chip
, gpio
- chip
->base
) : 0;
1562 EXPORT_SYMBOL_GPL(gpio_get_value_cansleep
);
1564 void gpio_set_value_cansleep(unsigned gpio
, int value
)
1566 struct gpio_chip
*chip
;
1568 might_sleep_if(extra_checks
);
1569 chip
= gpio_to_chip(gpio
);
1570 chip
->set(chip
, gpio
- chip
->base
, value
);
1572 EXPORT_SYMBOL_GPL(gpio_set_value_cansleep
);
1575 #ifdef CONFIG_DEBUG_FS
1577 static void gpiolib_dbg_show(struct seq_file
*s
, struct gpio_chip
*chip
)
1580 unsigned gpio
= chip
->base
;
1581 struct gpio_desc
*gdesc
= &gpio_desc
[gpio
];
1584 for (i
= 0; i
< chip
->ngpio
; i
++, gpio
++, gdesc
++) {
1585 if (!test_bit(FLAG_REQUESTED
, &gdesc
->flags
))
1588 is_out
= test_bit(FLAG_IS_OUT
, &gdesc
->flags
);
1589 seq_printf(s
, " gpio-%-3d (%-20.20s) %s %s",
1591 is_out
? "out" : "in ",
1593 ? (chip
->get(chip
, i
) ? "hi" : "lo")
1597 int irq
= gpio_to_irq(gpio
);
1598 struct irq_desc
*desc
= irq_to_desc(irq
);
1600 /* This races with request_irq(), set_irq_type(),
1601 * and set_irq_wake() ... but those are "rare".
1603 * More significantly, trigger type flags aren't
1604 * currently maintained by genirq.
1606 if (irq
>= 0 && desc
->action
) {
1609 switch (desc
->status
& IRQ_TYPE_SENSE_MASK
) {
1611 trigger
= "(default)";
1613 case IRQ_TYPE_EDGE_FALLING
:
1614 trigger
= "edge-falling";
1616 case IRQ_TYPE_EDGE_RISING
:
1617 trigger
= "edge-rising";
1619 case IRQ_TYPE_EDGE_BOTH
:
1620 trigger
= "edge-both";
1622 case IRQ_TYPE_LEVEL_HIGH
:
1623 trigger
= "level-high";
1625 case IRQ_TYPE_LEVEL_LOW
:
1626 trigger
= "level-low";
1629 trigger
= "?trigger?";
1633 seq_printf(s
, " irq-%d %s%s",
1635 (desc
->status
& IRQ_WAKEUP
)
1640 seq_printf(s
, "\n");
1644 static int gpiolib_show(struct seq_file
*s
, void *unused
)
1646 struct gpio_chip
*chip
= NULL
;
1650 /* REVISIT this isn't locked against gpio_chip removal ... */
1652 for (gpio
= 0; gpio_is_valid(gpio
); gpio
++) {
1655 if (chip
== gpio_desc
[gpio
].chip
)
1657 chip
= gpio_desc
[gpio
].chip
;
1661 seq_printf(s
, "%sGPIOs %d-%d",
1662 started
? "\n" : "",
1663 chip
->base
, chip
->base
+ chip
->ngpio
- 1);
1666 seq_printf(s
, ", %s/%s",
1667 dev
->bus
? dev
->bus
->name
: "no-bus",
1670 seq_printf(s
, ", %s", chip
->label
);
1671 if (chip
->can_sleep
)
1672 seq_printf(s
, ", can sleep");
1673 seq_printf(s
, ":\n");
1677 chip
->dbg_show(s
, chip
);
1679 gpiolib_dbg_show(s
, chip
);
1684 static int gpiolib_open(struct inode
*inode
, struct file
*file
)
1686 return single_open(file
, gpiolib_show
, NULL
);
1689 static const struct file_operations gpiolib_operations
= {
1690 .open
= gpiolib_open
,
1692 .llseek
= seq_lseek
,
1693 .release
= single_release
,
1696 static int __init
gpiolib_debugfs_init(void)
1698 /* /sys/kernel/debug/gpio */
1699 (void) debugfs_create_file("gpio", S_IFREG
| S_IRUGO
,
1700 NULL
, NULL
, &gpiolib_operations
);
1703 subsys_initcall(gpiolib_debugfs_init
);
1705 #endif /* DEBUG_FS */