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
10 - leds-gpio: drivers/leds/leds-gpio.c will handle LEDs connected to  GPIO
14   i.e. a LED will turn on/off in response to a GPIO line going high or low
17 - gpio-keys: drivers/input/keyboard/gpio_keys.c is used when your GPIO line
21   GPIO line cannot generate interrupts, so it needs to be periodically polled
26   mouse cable and connect the wires to GPIO lines or solder a mouse connector
30   an external speaker connected to a GPIO line. (If the beep is controlled by
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
39   HDMI connector. It will provide a better userspace sysfs interface than GPIO.
42   the system by pulling a GPIO line and will register a restart handler so
46   system down by pulling a GPIO line and will register a pm_power_off()
51   (off/on) that uses a GPIO, and integrated with the clock subsystem.
54   (two wires, SDA and SCL lines) by hammering (bitbang) two GPIO lines. It will
60   GPIO hammering (bitbang). It will appear as any other SPI bus on the system
66   a GPIO line, integrating with the W1 subsystem and handling devices on
70   system, connected to a GPIO line (and optionally a GPIO alarm line),
75   regulator providing a certain voltage by pulling a GPIO line, integrating
79   that will periodically "ping" a hardware connected to a GPIO line by toggling
84   to a set of simple GPIO lines: RDY, NCE, ALE, CLE, NWP. It interacts with the
89   bus, data and clock line, by bit banging two GPIO lines. It will appear as
94   Consumer Electronics Control bus using only GPIO. It is used to communicate
100   nothing but GPIO lines, this driver provides that and also a clearly defined
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
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