driver-api/gpio/consumer.rst

6 it describes the new descriptor-based interface. For a description of the
7 deprecated integer-based GPIO interface please refer to legacy.rst.
23 - Simple compile coverage with e.g. COMPILE_TEST - it does not matter that
27 - Truly optional GPIOLIB support - where the driver does not really make use
28   of the GPIOs on certain compile-time configurations for certain systems, but
29   will use it under other compile-time configurations. In this case the
35   some open coding of error handling should be expected when you do this.
37 All the functions that work with the descriptor-based GPIO interface are
47 With the descriptor-based interface, GPIOs are identified with an opaque,
48 non-forgeable handler that must be obtained through a call to one of the
56 If a function is implemented by using several GPIOs together (e.g. a simple LED
64 see Documentation/driver-api/gpio/board.rst
75   to be electrically used with open drain.
77   to be electrically used with open drain.
83 The two last flags are used for use cases where open drain is mandatory, such
84 as I2C: if the line is not already configured as open drain in the mappings
85 (see board.rst), then open drain will be enforced anyway and a warning will be
89 with IS_ERR() (they will never return a NULL pointer). -ENOENT will be returned
96 instead of -ENOENT if no GPIO has been assigned to the requested function::
110 -ENOSYS return codes.  System integrators should however be careful to enable
129 The following function returns NULL instead of -ENOENT if no GPIOs have been
136 Device-managed variants of these functions are also defined::
175 The device-managed variants are, unsurprisingly::
186 -----------------
188 direction-setting flags have been given to gpiod_get*(), this is done by
197 for spinlock-safe GPIOs it is OK to use them before tasking is enabled, as part
214 Spinlock-Safe GPIO Access
215 -------------------------
217 don't need to sleep, and can safely be done from inside hard (non-threaded) IRQ
228 open-drain signaling and output latencies.
238 --------------------------
255 IRQ handler, and those accessors must be used instead of spinlock-safe
260 spinlock-safe calls.
265 The active low and open drain semantics
266 ---------------------------------------
274 The same is applicable for open drain or open source output lines: those do not
275 actively drive their output high (open drain) or low (open source), they just
277 care. (For details read about open drain in driver.rst.)
280 parameter "value" as "asserted" ("1") or "de-asserted" ("0"). The physical line
296   gpiod_set_value(desc, 0);          open drain             low
297   gpiod_set_value(desc, 1);          open drain             high impedance
298   gpiod_set_value(desc, 0);          open source            high impedance
299   gpiod_set_value(desc, 1);          open source            high
302 but it should be avoided as much as possible, especially by system-agnostic drivers
308 -------------------------
313 The following set of calls ignore the active-low or open drain property of a GPIO and
329 should not have to care about the physical line level or open drain semantics.
333 -------------------------------------------------
378 	* array_size	- the number of array elements
379 	* desc_array	- an array of GPIO descriptors
380 	* array_info	- optional information obtained from gpiod_get_array()
381 	* value_bitmap	- a bitmap to store the GPIOs' values (get) or
390 	gpiod_set_array_value(my_gpio_descs->ndescs, my_gpio_descs->desc,
391 			      my_gpio_descs->info, my_gpio_value_bitmap);
417 --------------------
429 Non-error values returned from gpiod_to_irq() can be passed to request_irq() or
431 by the board-specific initialization code. Note that IRQ trigger options are
451 For details refer to Documentation/firmware-guide/acpi/gpio-properties.rst
457 integer-based interface. It is strongly recommended to update these to the new
460 and vice-versa::