driver-api/gpio/drivers-on-gpio.rst

2 Subsystem drivers using GPIO
5 Note that standard kernel drivers exist for common GPIO tasks and will provide
6 the right in-kernel and userspace APIs/ABIs for the job, and that these
10 - leds-gpio: drivers/leds/leds-gpio.c will handle LEDs connected to  GPIO
13 - ledtrig-gpio: drivers/leds/trigger/ledtrig-gpio.c will provide a LED trigger,
14   i.e. a LED will turn on/off in response to a GPIO line going high or low
15   (and that LED may in turn use the leds-gpio as per above).
17 - gpio-keys: drivers/input/keyboard/gpio_keys.c is used when your GPIO line
20 - gpio-keys-polled: drivers/input/keyboard/gpio_keys_polled.c is used when your
21   GPIO line cannot generate interrupts, so it needs to be periodically polled
24 - gpio_mouse: drivers/input/mouse/gpio_mouse.c is used to provide a mouse with
26   mouse cable and connect the wires to GPIO lines or solder a mouse connector
29 - gpio-beeper: drivers/input/misc/gpio-beeper.c is used to provide a beep from
30   an external speaker connected to a GPIO line. (If the beep is controlled by
31   off/on, for an actual PWM waveform, see pwm-gpio below.)
33 - pwm-gpio: drivers/pwm/pwm-gpio.c is used to toggle a GPIO with a high
34   resolution timer producing a PWM waveform on the GPIO line, as well as
37 - extcon-gpio: drivers/extcon/extcon-gpio.c is used when you need to read an
39   HDMI connector. It will provide a better userspace sysfs interface than GPIO.
41 - restart-gpio: drivers/power/reset/gpio-restart.c is used to restart/reboot
42   the system by pulling a GPIO line and will register a restart handler so
45 - poweroff-gpio: drivers/power/reset/gpio-poweroff.c is used to power the
46   system down by pulling a GPIO line and will register a pm_power_off()
50 - gpio-gate-clock: drivers/clk/clk-gpio.c is used to control a gated clock
51   (off/on) that uses a GPIO, and integrated with the clock subsystem.
53 - i2c-gpio: drivers/i2c/busses/i2c-gpio.c is used to drive an I2C bus
54   (two wires, SDA and SCL lines) by hammering (bitbang) two GPIO lines. It will
58 - spi_gpio: drivers/spi/spi-gpio.c is used to drive an SPI bus (variable number
60   GPIO hammering (bitbang). It will appear as any other SPI bus on the system
61   and makes it possible to connect drivers for SPI devices on the bus like
62   any other SPI bus driver. For example any MMC/SD card can then be connected
63   to this SPI by using the mmc_spi host from the MMC/SD card subsystem.
65 - w1-gpio: drivers/w1/masters/w1-gpio.c is used to drive a one-wire bus using
66   a GPIO line, integrating with the W1 subsystem and handling devices on
69 - gpio-fan: drivers/hwmon/gpio-fan.c is used to control a fan for cooling the
70   system, connected to a GPIO line (and optionally a GPIO alarm line),
71   presenting all the right in-kernel and sysfs interfaces to make your system
74 - gpio-regulator: drivers/regulator/gpio-regulator.c is used to control a
75   regulator providing a certain voltage by pulling a GPIO line, integrating
78 - gpio-wdt: drivers/watchdog/gpio_wdt.c is used to provide a watchdog timer
79   that will periodically "ping" a hardware connected to a GPIO line by toggling
80   it from 1-to-0-to-1. If that hardware does not receive its "ping"
83 - gpio-nand: drivers/mtd/nand/raw/gpio.c is used to connect a NAND flash chip
84   to a set of simple GPIO lines: RDY, NCE, ALE, CLE, NWP. It interacts with the
88 - ps2-gpio: drivers/input/serio/ps2-gpio.c is used to drive a PS/2 (IBM) serio
89   bus, data and clock line, by bit banging two GPIO lines. It will appear as
93 - cec-gpio: drivers/media/platform/cec-gpio/ is used to interact with a CEC
94   Consumer Electronics Control bus using only GPIO. It is used to communicate
97 - gpio-charger: drivers/power/supply/gpio-charger.c is used if you need to do
100   nothing but GPIO lines, this driver provides that and also a clearly defined
104 - gpio-mux: drivers/mux/gpio.c is used for controlling a multiplexer using
105   n GPIO lines such that you can mux in 2^n different devices by activating
106   different GPIO lines. Often the GPIOs are on a SoC and the devices are
107   some SoC-external entities, such as different components on a PCB that
110 Apart from this there are special GPIO drivers in subsystems like MMC/SD to
111 read card detect and write protect GPIO lines, and in the TTY serial subsystem
112 to emulate MCTRL (modem control) signals CTS/RTS by using two GPIO lines. The
113 MTD NOR flash has add-ons for extra GPIO lines too, though the address bus is
119 speed up your embedded hacking in particular by providing ready-made components.