driver-api/gpio/consumer.rst

21 - Simple compile coverage with e.g. COMPILE_TEST - it does not matter that
25 - Truly optional GPIOLIB support - where the driver does not really make use
26   of the GPIOs on certain compile-time configurations for certain systems, but
27   will use it under other compile-time configurations. In this case the
35 All the functions that work with the descriptor-based GPIO interface are
45 With the descriptor-based interface, GPIOs are identified with an opaque,
46 non-forgeable handler that must be obtained through a call to one of the
62 see Documentation/driver-api/gpio/board.rst
78 whether the line is configured active high or active low (see
87 with IS_ERR() (they will never return a NULL pointer). -ENOENT will be returned
94 instead of -ENOENT if no GPIO has been assigned to the requested function::
108 -ENOSYS return codes.  System integrators should however be careful to enable
127 The following function returns NULL instead of -ENOENT if no GPIOs have been
134 Device-managed variants of these functions are also defined::
173 The device-managed variants are, unsurprisingly::
184 -----------------
186 direction-setting flags have been given to gpiod_get*(), this is done by
195 for spinlock-safe GPIOs it is OK to use them before tasking is enabled, as part
212 Spinlock-Safe GPIO Access
213 -------------------------
215 don't need to sleep, and can safely be done from inside hard (non-threaded) IRQ
223 The values are boolean, zero for inactive, nonzero for active. When reading the
226 open-drain signaling and output latencies.
236 --------------------------
240 sleeping, which can't be done from inside IRQ handlers.
253 IRQ handler, and those accessors must be used instead of spinlock-safe
258 spinlock-safe calls.
263 The active low and open drain semantics
264 ---------------------------------------
267 the *logical* value. With this they take the active low property into account.
268 This means that they check whether the GPIO is configured to be active low,
273 actively drive their output high (open drain) or low (open source), they just
274 switch their output to a high impedance value. The consumer should not need to
278 parameter "value" as "active" ("1") or "inactive" ("0"). The physical line
281 As an example, if the active low property for a dedicated GPIO is set, and the
282 gpiod_set_(array)_value_xxx() passes "active" ("1"), the physical line level
289   gpiod_set_raw_value(desc, 1);      don't care             high
290   gpiod_set_value(desc, 0);          default (active high)  low
291   gpiod_set_value(desc, 1);          default (active high)  high
292   gpiod_set_value(desc, 0);          active low             high
293   gpiod_set_value(desc, 1);          active low             low
295   gpiod_set_value(desc, 1);          open drain             high impedance
296   gpiod_set_value(desc, 0);          open source            high impedance
297   gpiod_set_value(desc, 1);          open source            high
300 but it should be avoided as much as possible, especially by system-agnostic drivers
306 -------------------------
311 The following set of calls ignore the active-low or open drain property of a GPIO and
320 The active low state of a GPIO can also be queried and toggled using the
331 -------------------------------------------------
376 	* array_size	- the number of array elements
377 	* desc_array	- an array of GPIO descriptors
378 	* array_info	- optional information obtained from gpiod_get_array()
379 	* value_bitmap	- a bitmap to store the GPIOs' values (get) or
388 	gpiod_set_array_value(my_gpio_descs->ndescs, my_gpio_descs->desc,
389 			      my_gpio_descs->info, my_gpio_value_bitmap);
415 --------------------
416 GPIO lines can quite often be used as IRQs. You can get the IRQ number
421 It will return an IRQ number, or a negative errno code if the mapping can't be
422 done (most likely because that particular GPIO cannot be used as IRQ). It is an
424 gpiod_direction_input(), or to use an IRQ number that didn't originally come
427 Non-error values returned from gpiod_to_irq() can be passed to request_irq() or
428 free_irq(). They will often be stored into IRQ resources for platform devices,
429 by the board-specific initialization code. Note that IRQ trigger options are
430 part of the IRQ interface, e.g. IRQF_TRIGGER_FALLING, as are system wakeup
449 For details refer to Documentation/firmware-guide/acpi/gpio-properties.rst
455 integer-based interface. It is strongly recommended to update these to the new
458 and vice-versa::