diff options
Diffstat (limited to 'Documentation/i2c/muxes')
| -rw-r--r-- | Documentation/i2c/muxes/i2c-mux-gpio (renamed from Documentation/i2c/muxes/gpio-i2cmux) | 30 |
1 files changed, 24 insertions, 6 deletions
diff --git a/Documentation/i2c/muxes/gpio-i2cmux b/Documentation/i2c/muxes/i2c-mux-gpio index 811cd78d4cd..d4d91a53fc3 100644 --- a/Documentation/i2c/muxes/gpio-i2cmux +++ b/Documentation/i2c/muxes/i2c-mux-gpio @@ -1,11 +1,11 @@ -Kernel driver gpio-i2cmux +Kernel driver i2c-gpio-mux Author: Peter Korsgaard <peter.korsgaard@barco.com> Description ----------- -gpio-i2cmux is an i2c mux driver providing access to I2C bus segments +i2c-gpio-mux is an i2c mux driver providing access to I2C bus segments from a master I2C bus and a hardware MUX controlled through GPIO pins. E.G.: @@ -26,16 +26,16 @@ according to the settings of the GPIO pins 1..N. Usage ----- -gpio-i2cmux uses the platform bus, so you need to provide a struct +i2c-gpio-mux uses the platform bus, so you need to provide a struct platform_device with the platform_data pointing to a struct gpio_i2cmux_platform_data with the I2C adapter number of the master bus, the number of bus segments to create and the GPIO pins used -to control it. See include/linux/gpio-i2cmux.h for details. +to control it. See include/linux/i2c-gpio-mux.h for details. E.G. something like this for a MUX providing 4 bus segments controlled through 3 GPIO pins: -#include <linux/gpio-i2cmux.h> +#include <linux/i2c-gpio-mux.h> #include <linux/platform_device.h> static const unsigned myboard_gpiomux_gpios[] = { @@ -57,9 +57,27 @@ static struct gpio_i2cmux_platform_data myboard_i2cmux_data = { }; static struct platform_device myboard_i2cmux = { - .name = "gpio-i2cmux", + .name = "i2c-gpio-mux", .id = 0, .dev = { .platform_data = &myboard_i2cmux_data, }, }; + +If you don't know the absolute GPIO pin numbers at registration time, +you can instead provide a chip name (.chip_name) and relative GPIO pin +numbers, and the i2c-gpio-mux driver will do the work for you, +including deferred probing if the GPIO chip isn't immediately +available. + +Device Registration +------------------- + +When registering your i2c-gpio-mux device, you should pass the number +of any GPIO pin it uses as the device ID. This guarantees that every +instance has a different ID. + +Alternatively, if you don't need a stable device name, you can simply +pass PLATFORM_DEVID_AUTO as the device ID, and the platform core will +assign a dynamic ID to your device. If you do not know the absolute +GPIO pin numbers at registration time, this is even the only option. |