diff options
Diffstat (limited to 'Documentation/driver-api/gpio/drivers-on-gpio.rst')
| -rw-r--r-- | Documentation/driver-api/gpio/drivers-on-gpio.rst | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/Documentation/driver-api/gpio/drivers-on-gpio.rst b/Documentation/driver-api/gpio/drivers-on-gpio.rst index f3a189320e11..af632d764ac6 100644 --- a/Documentation/driver-api/gpio/drivers-on-gpio.rst +++ b/Documentation/driver-api/gpio/drivers-on-gpio.rst @@ -89,13 +89,26 @@ hardware descriptions such as device tree or ACPI: Consumer Electronics Control bus using only GPIO. It is used to communicate with devices on the HDMI bus. +- gpio-charger: drivers/power/supply/gpio-charger.c is used if you need to do + battery charging and all you have to go by to check the presence of the + AC charger or more complex tasks such as indicating charging status using + nothing but GPIO lines, this driver provides that and also a clearly defined + way to pass the charging parameters from hardware descriptions such as the + device tree. + +- gpio-mux: drivers/mux/gpio.c is used for controlling a multiplexer using + n GPIO lines such that you can mux in 2^n different devices by activating + different GPIO lines. Often the GPIOs are on a SoC and the devices are + some SoC-external entities, such as different components on a PCB that + can be selectively enabled. + Apart from this there are special GPIO drivers in subsystems like MMC/SD to read card detect and write protect GPIO lines, and in the TTY serial subsystem to emulate MCTRL (modem control) signals CTS/RTS by using two GPIO lines. The MTD NOR flash has add-ons for extra GPIO lines too, though the address bus is usually connected directly to the flash. -Use those instead of talking directly to the GPIOs using sysfs; they integrate -with kernel frameworks better than your userspace code could. Needless to say, -just using the appropriate kernel drivers will simplify and speed up your -embedded hacking in particular by providing ready-made components. +Use those instead of talking directly to the GPIOs from userspace; they +integrate with kernel frameworks better than your userspace code could. +Needless to say, just using the appropriate kernel drivers will simplify and +speed up your embedded hacking in particular by providing ready-made components. |