bindings/gpio/gpio.txt

1 Specifying GPIO information for devices
7 GPIO properties should be named "[<name>-]gpios", with <name> being the purpose
8 of this GPIO for the device. While a non-existent <name> is considered valid
10 for new bindings. Also, GPIO properties named "[<name>-]gpio" are valid and old
14 GPIO properties can contain one or more GPIO phandles, but only in exceptional
23 The following example could be used to describe GPIO pins used as device enable
38 a local offset to the GPIO line and the second cell represent consumer flags,
57 GPIO pin number, and GPIO flags as accepted by the "qe_pio_e" gpio-controller.
83 1.1) GPIO specifier best practices
86 A gpio-specifier should contain a flag indicating the GPIO polarity; active-
91 GPIO controller that achieves (or represents, for inputs) a logically asserted
94 the GPIO controller and the device, then the gpio-specifier will represent the
121 (at the GPIO controller) assuming that the device is configured for this
124 responsible for correctly interpreting (inverting) the GPIO signal at the GPIO
130 Every GPIO controller node must contain both an empty "gpio-controller"
134 Some system-on-chips (SoCs) use the concept of GPIO banks. A GPIO bank is an
141 Optionally, a GPIO controller may have a "ngpios" property. This property
155 Optionally, a GPIO controller may have a "gpio-line-names" property. This is
156 an array of strings defining the names of the GPIO lines going out of the
157 GPIO controller.
165 the line is used for. "GPIO0" is not a good name to give to a GPIO line
178 string) if the use of the GPIO line is undefined in your design. Ideally,
202 The GPIO chip may contain GPIO hog definitions. GPIO hogging is a mechanism
203 providing automatic GPIO request and configuration as part of the
206 Each GPIO hog definition is represented as a child node of the GPIO controller.
208 - gpio-hog:   A property specifying that this child node represents a GPIO hog.
209 - gpios:      Store the GPIO information (id, flags, ...) for each GPIO to
211 	      specified in its parent node (GPIO controller node).
216 - input:      A property specifying to set the GPIO direction as input.
217 - output-low  A property specifying to set the GPIO direction as output with
219 - output-high A property specifying to set the GPIO direction as output with
223 - line-name:  The GPIO label name. If not present the node name is used.
225 Example of two SOC GPIO banks defined as gpio-controller nodes:
251 Some or all of the GPIOs provided by a GPIO controller may be routed to pins
253 GPIO and other functions. It is a fairly common practice among silicon
256 2.2) Ordinary (numerical) GPIO ranges
262 to pins in the GPIO controller local number space.
264 The format is: <[pin controller phandle], [GPIO controller offset],
267 The GPIO controller offset pertains to the GPIO controller node containing the
274 ranges with just one pin-to-GPIO line mapping if the ranges are concocted, but
282 - pins 20..29 on pin controller "foo" is mapped to GPIO line 0..9 and
283 - pins 50..69 on pin controller "bar" is mapped to GPIO line 10..29
296 Here, a single GPIO controller has GPIOs 0..9 routed to pin controller
301 2.3) GPIO ranges from named pin groups
314 defined in the respective pin controller. The number of pins/GPIO lines in the
338 Here, three GPIO ranges are defined referring to two pin controllers.
340 pinctrl1 GPIO ranges are defined using pin numbers whereas the GPIO ranges