1 #include <linux/kernel.h>
2 #include <linux/module.h>
4 #include <linux/spinlock.h>
5 #include <linux/device.h>
7 #include <linux/debugfs.h>
8 #include <linux/seq_file.h>
9 #include <linux/gpio.h>
12 /* Optional implementation infrastructure for GPIO interfaces.
14 * Platforms may want to use this if they tend to use very many GPIOs
15 * that aren't part of a System-On-Chip core; or across I2C/SPI/etc.
17 * When kernel footprint or instruction count is an issue, simpler
18 * implementations may be preferred. The GPIO programming interface
19 * allows for inlining speed-critical get/set operations for common
20 * cases, so that access to SOC-integrated GPIOs can sometimes cost
21 * only an instruction or two per bit.
25 /* When debugging, extend minimal trust to callers and platform code.
26 * Also emit diagnostic messages that may help initial bringup, when
27 * board setup or driver bugs are most common.
29 * Otherwise, minimize overhead in what may be bitbanging codepaths.
32 #define extra_checks 1
34 #define extra_checks 0
37 /* gpio_lock prevents conflicts during gpio_desc[] table updates.
38 * While any GPIO is requested, its gpio_chip is not removable;
39 * each GPIO's "requested" flag serves as a lock and refcount.
41 static DEFINE_SPINLOCK(gpio_lock
);
44 struct gpio_chip
*chip
;
46 /* flag symbols are bit numbers */
47 #define FLAG_REQUESTED 0
49 #define FLAG_RESERVED 2
50 #define FLAG_EXPORT 3 /* protected by sysfs_lock */
51 #define FLAG_SYSFS 4 /* exported via /sys/class/gpio/control */
53 #ifdef CONFIG_DEBUG_FS
57 static struct gpio_desc gpio_desc
[ARCH_NR_GPIOS
];
59 static inline void desc_set_label(struct gpio_desc
*d
, const char *label
)
61 #ifdef CONFIG_DEBUG_FS
66 /* Warn when drivers omit gpio_request() calls -- legal but ill-advised
67 * when setting direction, and otherwise illegal. Until board setup code
68 * and drivers use explicit requests everywhere (which won't happen when
69 * those calls have no teeth) we can't avoid autorequesting. This nag
70 * message should motivate switching to explicit requests...
72 static void gpio_ensure_requested(struct gpio_desc
*desc
)
74 if (test_and_set_bit(FLAG_REQUESTED
, &desc
->flags
) == 0) {
75 pr_warning("GPIO-%d autorequested\n", (int)(desc
- gpio_desc
));
76 desc_set_label(desc
, "[auto]");
77 if (!try_module_get(desc
->chip
->owner
))
78 pr_err("GPIO-%d: module can't be gotten \n",
79 (int)(desc
- gpio_desc
));
83 /* caller holds gpio_lock *OR* gpio is marked as requested */
84 static inline struct gpio_chip
*gpio_to_chip(unsigned gpio
)
86 return gpio_desc
[gpio
].chip
;
89 /* dynamic allocation of GPIOs, e.g. on a hotplugged device */
90 static int gpiochip_find_base(int ngpio
)
96 for (i
= ARCH_NR_GPIOS
- 1; i
>= 0 ; i
--) {
97 struct gpio_desc
*desc
= &gpio_desc
[i
];
98 struct gpio_chip
*chip
= desc
->chip
;
100 if (!chip
&& !test_bit(FLAG_RESERVED
, &desc
->flags
)) {
102 if (spare
== ngpio
) {
109 i
-= chip
->ngpio
- 1;
113 if (gpio_is_valid(base
))
114 pr_debug("%s: found new base at %d\n", __func__
, base
);
119 * gpiochip_reserve() - reserve range of gpios to use with platform code only
120 * @start: starting gpio number
121 * @ngpio: number of gpios to reserve
122 * Context: platform init, potentially before irqs or kmalloc will work
124 * Returns a negative errno if any gpio within the range is already reserved
125 * or registered, else returns zero as a success code. Use this function
126 * to mark a range of gpios as unavailable for dynamic gpio number allocation,
127 * for example because its driver support is not yet loaded.
129 int __init
gpiochip_reserve(int start
, int ngpio
)
135 if (!gpio_is_valid(start
) || !gpio_is_valid(start
+ ngpio
- 1))
138 spin_lock_irqsave(&gpio_lock
, flags
);
140 for (i
= start
; i
< start
+ ngpio
; i
++) {
141 struct gpio_desc
*desc
= &gpio_desc
[i
];
143 if (desc
->chip
|| test_bit(FLAG_RESERVED
, &desc
->flags
)) {
148 set_bit(FLAG_RESERVED
, &desc
->flags
);
151 pr_debug("%s: reserved gpios from %d to %d\n",
152 __func__
, start
, start
+ ngpio
- 1);
154 spin_unlock_irqrestore(&gpio_lock
, flags
);
159 #ifdef CONFIG_GPIO_SYSFS
161 /* lock protects against unexport_gpio() being called while
162 * sysfs files are active.
164 static DEFINE_MUTEX(sysfs_lock
);
167 * /sys/class/gpio/gpioN... only for GPIOs that are exported
169 * * MAY BE OMITTED if kernel won't allow direction changes
170 * * is read/write as "in" or "out"
171 * * may also be written as "high" or "low", initializing
172 * output value as specified ("out" implies "low")
174 * * always readable, subject to hardware behavior
175 * * may be writable, as zero/nonzero
177 * REVISIT there will likely be an attribute for configuring async
178 * notifications, e.g. to specify polling interval or IRQ trigger type
179 * that would for example trigger a poll() on the "value".
182 static ssize_t
gpio_direction_show(struct device
*dev
,
183 struct device_attribute
*attr
, char *buf
)
185 const struct gpio_desc
*desc
= dev_get_drvdata(dev
);
188 mutex_lock(&sysfs_lock
);
190 if (!test_bit(FLAG_EXPORT
, &desc
->flags
))
193 status
= sprintf(buf
, "%s\n",
194 test_bit(FLAG_IS_OUT
, &desc
->flags
)
197 mutex_unlock(&sysfs_lock
);
201 static ssize_t
gpio_direction_store(struct device
*dev
,
202 struct device_attribute
*attr
, const char *buf
, size_t size
)
204 const struct gpio_desc
*desc
= dev_get_drvdata(dev
);
205 unsigned gpio
= desc
- gpio_desc
;
208 mutex_lock(&sysfs_lock
);
210 if (!test_bit(FLAG_EXPORT
, &desc
->flags
))
212 else if (sysfs_streq(buf
, "high"))
213 status
= gpio_direction_output(gpio
, 1);
214 else if (sysfs_streq(buf
, "out") || sysfs_streq(buf
, "low"))
215 status
= gpio_direction_output(gpio
, 0);
216 else if (sysfs_streq(buf
, "in"))
217 status
= gpio_direction_input(gpio
);
221 mutex_unlock(&sysfs_lock
);
222 return status
? : size
;
225 static const DEVICE_ATTR(direction
, 0644,
226 gpio_direction_show
, gpio_direction_store
);
228 static ssize_t
gpio_value_show(struct device
*dev
,
229 struct device_attribute
*attr
, char *buf
)
231 const struct gpio_desc
*desc
= dev_get_drvdata(dev
);
232 unsigned gpio
= desc
- gpio_desc
;
235 mutex_lock(&sysfs_lock
);
237 if (!test_bit(FLAG_EXPORT
, &desc
->flags
))
240 status
= sprintf(buf
, "%d\n", gpio_get_value_cansleep(gpio
));
242 mutex_unlock(&sysfs_lock
);
246 static ssize_t
gpio_value_store(struct device
*dev
,
247 struct device_attribute
*attr
, const char *buf
, size_t size
)
249 const struct gpio_desc
*desc
= dev_get_drvdata(dev
);
250 unsigned gpio
= desc
- gpio_desc
;
253 mutex_lock(&sysfs_lock
);
255 if (!test_bit(FLAG_EXPORT
, &desc
->flags
))
257 else if (!test_bit(FLAG_IS_OUT
, &desc
->flags
))
262 status
= strict_strtol(buf
, 0, &value
);
264 gpio_set_value_cansleep(gpio
, value
!= 0);
269 mutex_unlock(&sysfs_lock
);
273 static /*const*/ DEVICE_ATTR(value
, 0644,
274 gpio_value_show
, gpio_value_store
);
276 static const struct attribute
*gpio_attrs
[] = {
277 &dev_attr_direction
.attr
,
278 &dev_attr_value
.attr
,
282 static const struct attribute_group gpio_attr_group
= {
283 .attrs
= (struct attribute
**) gpio_attrs
,
287 * /sys/class/gpio/gpiochipN/
288 * /base ... matching gpio_chip.base (N)
289 * /label ... matching gpio_chip.label
290 * /ngpio ... matching gpio_chip.ngpio
293 static ssize_t
chip_base_show(struct device
*dev
,
294 struct device_attribute
*attr
, char *buf
)
296 const struct gpio_chip
*chip
= dev_get_drvdata(dev
);
298 return sprintf(buf
, "%d\n", chip
->base
);
300 static DEVICE_ATTR(base
, 0444, chip_base_show
, NULL
);
302 static ssize_t
chip_label_show(struct device
*dev
,
303 struct device_attribute
*attr
, char *buf
)
305 const struct gpio_chip
*chip
= dev_get_drvdata(dev
);
307 return sprintf(buf
, "%s\n", chip
->label
? : "");
309 static DEVICE_ATTR(label
, 0444, chip_label_show
, NULL
);
311 static ssize_t
chip_ngpio_show(struct device
*dev
,
312 struct device_attribute
*attr
, char *buf
)
314 const struct gpio_chip
*chip
= dev_get_drvdata(dev
);
316 return sprintf(buf
, "%u\n", chip
->ngpio
);
318 static DEVICE_ATTR(ngpio
, 0444, chip_ngpio_show
, NULL
);
320 static const struct attribute
*gpiochip_attrs
[] = {
322 &dev_attr_label
.attr
,
323 &dev_attr_ngpio
.attr
,
327 static const struct attribute_group gpiochip_attr_group
= {
328 .attrs
= (struct attribute
**) gpiochip_attrs
,
332 * /sys/class/gpio/export ... write-only
333 * integer N ... number of GPIO to export (full access)
334 * /sys/class/gpio/unexport ... write-only
335 * integer N ... number of GPIO to unexport
337 static ssize_t
export_store(struct class *class, const char *buf
, size_t len
)
342 status
= strict_strtol(buf
, 0, &gpio
);
346 /* No extra locking here; FLAG_SYSFS just signifies that the
347 * request and export were done by on behalf of userspace, so
348 * they may be undone on its behalf too.
351 status
= gpio_request(gpio
, "sysfs");
355 status
= gpio_export(gpio
, true);
359 set_bit(FLAG_SYSFS
, &gpio_desc
[gpio
].flags
);
363 pr_debug("%s: status %d\n", __func__
, status
);
364 return status
? : len
;
367 static ssize_t
unexport_store(struct class *class, const char *buf
, size_t len
)
372 status
= strict_strtol(buf
, 0, &gpio
);
378 /* reject bogus commands (gpio_unexport ignores them) */
379 if (!gpio_is_valid(gpio
))
382 /* No extra locking here; FLAG_SYSFS just signifies that the
383 * request and export were done by on behalf of userspace, so
384 * they may be undone on its behalf too.
386 if (test_and_clear_bit(FLAG_SYSFS
, &gpio_desc
[gpio
].flags
)) {
392 pr_debug("%s: status %d\n", __func__
, status
);
393 return status
? : len
;
396 static struct class_attribute gpio_class_attrs
[] = {
397 __ATTR(export
, 0200, NULL
, export_store
),
398 __ATTR(unexport
, 0200, NULL
, unexport_store
),
402 static struct class gpio_class
= {
404 .owner
= THIS_MODULE
,
406 .class_attrs
= gpio_class_attrs
,
411 * gpio_export - export a GPIO through sysfs
412 * @gpio: gpio to make available, already requested
413 * @direction_may_change: true if userspace may change gpio direction
414 * Context: arch_initcall or later
416 * When drivers want to make a GPIO accessible to userspace after they
417 * have requested it -- perhaps while debugging, or as part of their
418 * public interface -- they may use this routine. If the GPIO can
419 * change direction (some can't) and the caller allows it, userspace
420 * will see "direction" sysfs attribute which may be used to change
421 * the gpio's direction. A "value" attribute will always be provided.
423 * Returns zero on success, else an error.
425 int gpio_export(unsigned gpio
, bool direction_may_change
)
428 struct gpio_desc
*desc
;
429 int status
= -EINVAL
;
431 /* can't export until sysfs is available ... */
433 pr_debug("%s: called too early!\n", __func__
);
437 if (!gpio_is_valid(gpio
))
440 mutex_lock(&sysfs_lock
);
442 spin_lock_irqsave(&gpio_lock
, flags
);
443 desc
= &gpio_desc
[gpio
];
444 if (test_bit(FLAG_REQUESTED
, &desc
->flags
)
445 && !test_bit(FLAG_EXPORT
, &desc
->flags
)) {
447 if (!desc
->chip
->direction_input
448 || !desc
->chip
->direction_output
)
449 direction_may_change
= false;
451 spin_unlock_irqrestore(&gpio_lock
, flags
);
456 dev
= device_create(&gpio_class
, desc
->chip
->dev
, MKDEV(0, 0),
457 desc
, "gpio%d", gpio
);
459 if (direction_may_change
)
460 status
= sysfs_create_group(&dev
->kobj
,
463 status
= device_create_file(dev
,
466 device_unregister(dev
);
470 set_bit(FLAG_EXPORT
, &desc
->flags
);
473 mutex_unlock(&sysfs_lock
);
477 pr_debug("%s: gpio%d status %d\n", __func__
, gpio
, status
);
481 EXPORT_SYMBOL_GPL(gpio_export
);
483 static int match_export(struct device
*dev
, void *data
)
485 return dev_get_drvdata(dev
) == data
;
489 * gpio_unexport - reverse effect of gpio_export()
490 * @gpio: gpio to make unavailable
492 * This is implicit on gpio_free().
494 void gpio_unexport(unsigned gpio
)
496 struct gpio_desc
*desc
;
497 int status
= -EINVAL
;
499 if (!gpio_is_valid(gpio
))
502 mutex_lock(&sysfs_lock
);
504 desc
= &gpio_desc
[gpio
];
505 if (test_bit(FLAG_EXPORT
, &desc
->flags
)) {
506 struct device
*dev
= NULL
;
508 dev
= class_find_device(&gpio_class
, NULL
, desc
, match_export
);
510 clear_bit(FLAG_EXPORT
, &desc
->flags
);
512 device_unregister(dev
);
518 mutex_unlock(&sysfs_lock
);
521 pr_debug("%s: gpio%d status %d\n", __func__
, gpio
, status
);
523 EXPORT_SYMBOL_GPL(gpio_unexport
);
525 static int gpiochip_export(struct gpio_chip
*chip
)
530 /* Many systems register gpio chips for SOC support very early,
531 * before driver model support is available. In those cases we
532 * export this later, in gpiolib_sysfs_init() ... here we just
533 * verify that _some_ field of gpio_class got initialized.
538 /* use chip->base for the ID; it's already known to be unique */
539 mutex_lock(&sysfs_lock
);
540 dev
= device_create(&gpio_class
, chip
->dev
, MKDEV(0, 0), chip
,
541 "gpiochip%d", chip
->base
);
543 status
= sysfs_create_group(&dev
->kobj
,
544 &gpiochip_attr_group
);
547 chip
->exported
= (status
== 0);
548 mutex_unlock(&sysfs_lock
);
554 spin_lock_irqsave(&gpio_lock
, flags
);
556 while (gpio_desc
[gpio
].chip
== chip
)
557 gpio_desc
[gpio
++].chip
= NULL
;
558 spin_unlock_irqrestore(&gpio_lock
, flags
);
560 pr_debug("%s: chip %s status %d\n", __func__
,
561 chip
->label
, status
);
567 static void gpiochip_unexport(struct gpio_chip
*chip
)
572 mutex_lock(&sysfs_lock
);
573 dev
= class_find_device(&gpio_class
, NULL
, chip
, match_export
);
576 device_unregister(dev
);
581 mutex_unlock(&sysfs_lock
);
584 pr_debug("%s: chip %s status %d\n", __func__
,
585 chip
->label
, status
);
588 static int __init
gpiolib_sysfs_init(void)
594 status
= class_register(&gpio_class
);
598 /* Scan and register the gpio_chips which registered very
599 * early (e.g. before the class_register above was called).
601 * We run before arch_initcall() so chip->dev nodes can have
602 * registered, and so arch_initcall() can always gpio_export().
604 spin_lock_irqsave(&gpio_lock
, flags
);
605 for (gpio
= 0; gpio
< ARCH_NR_GPIOS
; gpio
++) {
606 struct gpio_chip
*chip
;
608 chip
= gpio_desc
[gpio
].chip
;
609 if (!chip
|| chip
->exported
)
612 spin_unlock_irqrestore(&gpio_lock
, flags
);
613 status
= gpiochip_export(chip
);
614 spin_lock_irqsave(&gpio_lock
, flags
);
616 spin_unlock_irqrestore(&gpio_lock
, flags
);
621 postcore_initcall(gpiolib_sysfs_init
);
624 static inline int gpiochip_export(struct gpio_chip
*chip
)
629 static inline void gpiochip_unexport(struct gpio_chip
*chip
)
633 #endif /* CONFIG_GPIO_SYSFS */
636 * gpiochip_add() - register a gpio_chip
637 * @chip: the chip to register, with chip->base initialized
638 * Context: potentially before irqs or kmalloc will work
640 * Returns a negative errno if the chip can't be registered, such as
641 * because the chip->base is invalid or already associated with a
642 * different chip. Otherwise it returns zero as a success code.
644 * When gpiochip_add() is called very early during boot, so that GPIOs
645 * can be freely used, the chip->dev device must be registered before
646 * the gpio framework's arch_initcall(). Otherwise sysfs initialization
647 * for GPIOs will fail rudely.
649 * If chip->base is negative, this requests dynamic assignment of
650 * a range of valid GPIOs.
652 int gpiochip_add(struct gpio_chip
*chip
)
657 int base
= chip
->base
;
659 if ((!gpio_is_valid(base
) || !gpio_is_valid(base
+ chip
->ngpio
- 1))
665 spin_lock_irqsave(&gpio_lock
, flags
);
668 base
= gpiochip_find_base(chip
->ngpio
);
676 /* these GPIO numbers must not be managed by another gpio_chip */
677 for (id
= base
; id
< base
+ chip
->ngpio
; id
++) {
678 if (gpio_desc
[id
].chip
!= NULL
) {
684 for (id
= base
; id
< base
+ chip
->ngpio
; id
++) {
685 gpio_desc
[id
].chip
= chip
;
687 /* REVISIT: most hardware initializes GPIOs as
688 * inputs (often with pullups enabled) so power
689 * usage is minimized. Linux code should set the
690 * gpio direction first thing; but until it does,
691 * we may expose the wrong direction in sysfs.
693 gpio_desc
[id
].flags
= !chip
->direction_input
700 spin_unlock_irqrestore(&gpio_lock
, flags
);
702 status
= gpiochip_export(chip
);
704 /* failures here can mean systems won't boot... */
706 pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n",
707 chip
->base
, chip
->base
+ chip
->ngpio
- 1,
708 chip
->label
? : "generic");
711 EXPORT_SYMBOL_GPL(gpiochip_add
);
714 * gpiochip_remove() - unregister a gpio_chip
715 * @chip: the chip to unregister
717 * A gpio_chip with any GPIOs still requested may not be removed.
719 int gpiochip_remove(struct gpio_chip
*chip
)
725 spin_lock_irqsave(&gpio_lock
, flags
);
727 for (id
= chip
->base
; id
< chip
->base
+ chip
->ngpio
; id
++) {
728 if (test_bit(FLAG_REQUESTED
, &gpio_desc
[id
].flags
)) {
734 for (id
= chip
->base
; id
< chip
->base
+ chip
->ngpio
; id
++)
735 gpio_desc
[id
].chip
= NULL
;
738 spin_unlock_irqrestore(&gpio_lock
, flags
);
741 gpiochip_unexport(chip
);
745 EXPORT_SYMBOL_GPL(gpiochip_remove
);
748 /* These "optional" allocation calls help prevent drivers from stomping
749 * on each other, and help provide better diagnostics in debugfs.
750 * They're called even less than the "set direction" calls.
752 int gpio_request(unsigned gpio
, const char *label
)
754 struct gpio_desc
*desc
;
755 int status
= -EINVAL
;
758 spin_lock_irqsave(&gpio_lock
, flags
);
760 if (!gpio_is_valid(gpio
))
762 desc
= &gpio_desc
[gpio
];
763 if (desc
->chip
== NULL
)
766 if (!try_module_get(desc
->chip
->owner
))
769 /* NOTE: gpio_request() can be called in early boot,
770 * before IRQs are enabled.
773 if (test_and_set_bit(FLAG_REQUESTED
, &desc
->flags
) == 0) {
774 desc_set_label(desc
, label
? : "?");
778 module_put(desc
->chip
->owner
);
783 pr_debug("gpio_request: gpio-%d (%s) status %d\n",
784 gpio
, label
? : "?", status
);
785 spin_unlock_irqrestore(&gpio_lock
, flags
);
788 EXPORT_SYMBOL_GPL(gpio_request
);
790 void gpio_free(unsigned gpio
)
793 struct gpio_desc
*desc
;
797 if (!gpio_is_valid(gpio
)) {
798 WARN_ON(extra_checks
);
804 spin_lock_irqsave(&gpio_lock
, flags
);
806 desc
= &gpio_desc
[gpio
];
807 if (desc
->chip
&& test_and_clear_bit(FLAG_REQUESTED
, &desc
->flags
)) {
808 desc_set_label(desc
, NULL
);
809 module_put(desc
->chip
->owner
);
811 WARN_ON(extra_checks
);
813 spin_unlock_irqrestore(&gpio_lock
, flags
);
815 EXPORT_SYMBOL_GPL(gpio_free
);
819 * gpiochip_is_requested - return string iff signal was requested
820 * @chip: controller managing the signal
821 * @offset: of signal within controller's 0..(ngpio - 1) range
823 * Returns NULL if the GPIO is not currently requested, else a string.
824 * If debugfs support is enabled, the string returned is the label passed
825 * to gpio_request(); otherwise it is a meaningless constant.
827 * This function is for use by GPIO controller drivers. The label can
828 * help with diagnostics, and knowing that the signal is used as a GPIO
829 * can help avoid accidentally multiplexing it to another controller.
831 const char *gpiochip_is_requested(struct gpio_chip
*chip
, unsigned offset
)
833 unsigned gpio
= chip
->base
+ offset
;
835 if (!gpio_is_valid(gpio
) || gpio_desc
[gpio
].chip
!= chip
)
837 if (test_bit(FLAG_REQUESTED
, &gpio_desc
[gpio
].flags
) == 0)
839 #ifdef CONFIG_DEBUG_FS
840 return gpio_desc
[gpio
].label
;
845 EXPORT_SYMBOL_GPL(gpiochip_is_requested
);
848 /* Drivers MUST set GPIO direction before making get/set calls. In
849 * some cases this is done in early boot, before IRQs are enabled.
851 * As a rule these aren't called more than once (except for drivers
852 * using the open-drain emulation idiom) so these are natural places
853 * to accumulate extra debugging checks. Note that we can't (yet)
854 * rely on gpio_request() having been called beforehand.
857 int gpio_direction_input(unsigned gpio
)
860 struct gpio_chip
*chip
;
861 struct gpio_desc
*desc
= &gpio_desc
[gpio
];
862 int status
= -EINVAL
;
864 spin_lock_irqsave(&gpio_lock
, flags
);
866 if (!gpio_is_valid(gpio
))
869 if (!chip
|| !chip
->get
|| !chip
->direction_input
)
872 if (gpio
>= chip
->ngpio
)
874 gpio_ensure_requested(desc
);
876 /* now we know the gpio is valid and chip won't vanish */
878 spin_unlock_irqrestore(&gpio_lock
, flags
);
880 might_sleep_if(extra_checks
&& chip
->can_sleep
);
882 status
= chip
->direction_input(chip
, gpio
);
884 clear_bit(FLAG_IS_OUT
, &desc
->flags
);
887 spin_unlock_irqrestore(&gpio_lock
, flags
);
889 pr_debug("%s: gpio-%d status %d\n",
890 __func__
, gpio
, status
);
893 EXPORT_SYMBOL_GPL(gpio_direction_input
);
895 int gpio_direction_output(unsigned gpio
, int value
)
898 struct gpio_chip
*chip
;
899 struct gpio_desc
*desc
= &gpio_desc
[gpio
];
900 int status
= -EINVAL
;
902 spin_lock_irqsave(&gpio_lock
, flags
);
904 if (!gpio_is_valid(gpio
))
907 if (!chip
|| !chip
->set
|| !chip
->direction_output
)
910 if (gpio
>= chip
->ngpio
)
912 gpio_ensure_requested(desc
);
914 /* now we know the gpio is valid and chip won't vanish */
916 spin_unlock_irqrestore(&gpio_lock
, flags
);
918 might_sleep_if(extra_checks
&& chip
->can_sleep
);
920 status
= chip
->direction_output(chip
, gpio
, value
);
922 set_bit(FLAG_IS_OUT
, &desc
->flags
);
925 spin_unlock_irqrestore(&gpio_lock
, flags
);
927 pr_debug("%s: gpio-%d status %d\n",
928 __func__
, gpio
, status
);
931 EXPORT_SYMBOL_GPL(gpio_direction_output
);
934 /* I/O calls are only valid after configuration completed; the relevant
935 * "is this a valid GPIO" error checks should already have been done.
937 * "Get" operations are often inlinable as reading a pin value register,
938 * and masking the relevant bit in that register.
940 * When "set" operations are inlinable, they involve writing that mask to
941 * one register to set a low value, or a different register to set it high.
942 * Otherwise locking is needed, so there may be little value to inlining.
944 *------------------------------------------------------------------------
946 * IMPORTANT!!! The hot paths -- get/set value -- assume that callers
947 * have requested the GPIO. That can include implicit requesting by
948 * a direction setting call. Marking a gpio as requested locks its chip
949 * in memory, guaranteeing that these table lookups need no more locking
950 * and that gpiochip_remove() will fail.
952 * REVISIT when debugging, consider adding some instrumentation to ensure
953 * that the GPIO was actually requested.
957 * __gpio_get_value() - return a gpio's value
958 * @gpio: gpio whose value will be returned
961 * This is used directly or indirectly to implement gpio_get_value().
962 * It returns the zero or nonzero value provided by the associated
963 * gpio_chip.get() method; or zero if no such method is provided.
965 int __gpio_get_value(unsigned gpio
)
967 struct gpio_chip
*chip
;
969 chip
= gpio_to_chip(gpio
);
970 WARN_ON(extra_checks
&& chip
->can_sleep
);
971 return chip
->get
? chip
->get(chip
, gpio
- chip
->base
) : 0;
973 EXPORT_SYMBOL_GPL(__gpio_get_value
);
976 * __gpio_set_value() - assign a gpio's value
977 * @gpio: gpio whose value will be assigned
978 * @value: value to assign
981 * This is used directly or indirectly to implement gpio_set_value().
982 * It invokes the associated gpio_chip.set() method.
984 void __gpio_set_value(unsigned gpio
, int value
)
986 struct gpio_chip
*chip
;
988 chip
= gpio_to_chip(gpio
);
989 WARN_ON(extra_checks
&& chip
->can_sleep
);
990 chip
->set(chip
, gpio
- chip
->base
, value
);
992 EXPORT_SYMBOL_GPL(__gpio_set_value
);
995 * __gpio_cansleep() - report whether gpio value access will sleep
996 * @gpio: gpio in question
999 * This is used directly or indirectly to implement gpio_cansleep(). It
1000 * returns nonzero if access reading or writing the GPIO value can sleep.
1002 int __gpio_cansleep(unsigned gpio
)
1004 struct gpio_chip
*chip
;
1006 /* only call this on GPIOs that are valid! */
1007 chip
= gpio_to_chip(gpio
);
1009 return chip
->can_sleep
;
1011 EXPORT_SYMBOL_GPL(__gpio_cansleep
);
1015 /* There's no value in making it easy to inline GPIO calls that may sleep.
1016 * Common examples include ones connected to I2C or SPI chips.
1019 int gpio_get_value_cansleep(unsigned gpio
)
1021 struct gpio_chip
*chip
;
1023 might_sleep_if(extra_checks
);
1024 chip
= gpio_to_chip(gpio
);
1025 return chip
->get(chip
, gpio
- chip
->base
);
1027 EXPORT_SYMBOL_GPL(gpio_get_value_cansleep
);
1029 void gpio_set_value_cansleep(unsigned gpio
, int value
)
1031 struct gpio_chip
*chip
;
1033 might_sleep_if(extra_checks
);
1034 chip
= gpio_to_chip(gpio
);
1035 chip
->set(chip
, gpio
- chip
->base
, value
);
1037 EXPORT_SYMBOL_GPL(gpio_set_value_cansleep
);
1040 #ifdef CONFIG_DEBUG_FS
1042 static void gpiolib_dbg_show(struct seq_file
*s
, struct gpio_chip
*chip
)
1045 unsigned gpio
= chip
->base
;
1046 struct gpio_desc
*gdesc
= &gpio_desc
[gpio
];
1049 for (i
= 0; i
< chip
->ngpio
; i
++, gpio
++, gdesc
++) {
1050 if (!test_bit(FLAG_REQUESTED
, &gdesc
->flags
))
1053 is_out
= test_bit(FLAG_IS_OUT
, &gdesc
->flags
);
1054 seq_printf(s
, " gpio-%-3d (%-12s) %s %s",
1056 is_out
? "out" : "in ",
1058 ? (chip
->get(chip
, i
) ? "hi" : "lo")
1062 int irq
= gpio_to_irq(gpio
);
1063 struct irq_desc
*desc
= irq_desc
+ irq
;
1065 /* This races with request_irq(), set_irq_type(),
1066 * and set_irq_wake() ... but those are "rare".
1068 * More significantly, trigger type flags aren't
1069 * currently maintained by genirq.
1071 if (irq
>= 0 && desc
->action
) {
1074 switch (desc
->status
& IRQ_TYPE_SENSE_MASK
) {
1076 trigger
= "(default)";
1078 case IRQ_TYPE_EDGE_FALLING
:
1079 trigger
= "edge-falling";
1081 case IRQ_TYPE_EDGE_RISING
:
1082 trigger
= "edge-rising";
1084 case IRQ_TYPE_EDGE_BOTH
:
1085 trigger
= "edge-both";
1087 case IRQ_TYPE_LEVEL_HIGH
:
1088 trigger
= "level-high";
1090 case IRQ_TYPE_LEVEL_LOW
:
1091 trigger
= "level-low";
1094 trigger
= "?trigger?";
1098 seq_printf(s
, " irq-%d %s%s",
1100 (desc
->status
& IRQ_WAKEUP
)
1105 seq_printf(s
, "\n");
1109 static int gpiolib_show(struct seq_file
*s
, void *unused
)
1111 struct gpio_chip
*chip
= NULL
;
1115 /* REVISIT this isn't locked against gpio_chip removal ... */
1117 for (gpio
= 0; gpio_is_valid(gpio
); gpio
++) {
1120 if (chip
== gpio_desc
[gpio
].chip
)
1122 chip
= gpio_desc
[gpio
].chip
;
1126 seq_printf(s
, "%sGPIOs %d-%d",
1127 started
? "\n" : "",
1128 chip
->base
, chip
->base
+ chip
->ngpio
- 1);
1131 seq_printf(s
, ", %s/%s",
1132 dev
->bus
? dev
->bus
->name
: "no-bus",
1135 seq_printf(s
, ", %s", chip
->label
);
1136 if (chip
->can_sleep
)
1137 seq_printf(s
, ", can sleep");
1138 seq_printf(s
, ":\n");
1142 chip
->dbg_show(s
, chip
);
1144 gpiolib_dbg_show(s
, chip
);
1149 static int gpiolib_open(struct inode
*inode
, struct file
*file
)
1151 return single_open(file
, gpiolib_show
, NULL
);
1154 static struct file_operations gpiolib_operations
= {
1155 .open
= gpiolib_open
,
1157 .llseek
= seq_lseek
,
1158 .release
= single_release
,
1161 static int __init
gpiolib_debugfs_init(void)
1163 /* /sys/kernel/debug/gpio */
1164 (void) debugfs_create_file("gpio", S_IFREG
| S_IRUGO
,
1165 NULL
, NULL
, &gpiolib_operations
);
1168 subsys_initcall(gpiolib_debugfs_init
);
1170 #endif /* DEBUG_FS */