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Diffstat (limited to 'Documentation/i2c/muxes/i2c-mux-gpio')
-rw-r--r-- | Documentation/i2c/muxes/i2c-mux-gpio | 83 |
1 files changed, 0 insertions, 83 deletions
diff --git a/Documentation/i2c/muxes/i2c-mux-gpio b/Documentation/i2c/muxes/i2c-mux-gpio deleted file mode 100644 index 893ecdfe6e43..000000000000 --- a/Documentation/i2c/muxes/i2c-mux-gpio +++ /dev/null @@ -1,83 +0,0 @@ -Kernel driver i2c-mux-gpio - -Author: Peter Korsgaard <peter.korsgaard@barco.com> - -Description ------------ - -i2c-mux-gpio 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.: - - ---------- ---------- Bus segment 1 - - - - - - | | SCL/SDA | |-------------- | | - | |------------| | - | | | | Bus segment 2 | | - | Linux | GPIO 1..N | MUX |--------------- Devices - | |------------| | | | - | | | | Bus segment M - | | | |---------------| | - ---------- ---------- - - - - - - -SCL/SDA of the master I2C bus is multiplexed to bus segment 1..M -according to the settings of the GPIO pins 1..N. - -Usage ------ - -i2c-mux-gpio uses the platform bus, so you need to provide a struct -platform_device with the platform_data pointing to a struct -i2c_mux_gpio_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/platform_data/i2c-mux-gpio.h for details. - -E.G. something like this for a MUX providing 4 bus segments -controlled through 3 GPIO pins: - -#include <linux/platform_data/i2c-mux-gpio.h> -#include <linux/platform_device.h> - -static const unsigned myboard_gpiomux_gpios[] = { - AT91_PIN_PC26, AT91_PIN_PC25, AT91_PIN_PC24 -}; - -static const unsigned myboard_gpiomux_values[] = { - 0, 1, 2, 3 -}; - -static struct i2c_mux_gpio_platform_data myboard_i2cmux_data = { - .parent = 1, - .base_nr = 2, /* optional */ - .values = myboard_gpiomux_values, - .n_values = ARRAY_SIZE(myboard_gpiomux_values), - .gpios = myboard_gpiomux_gpios, - .n_gpios = ARRAY_SIZE(myboard_gpiomux_gpios), - .idle = 4, /* optional */ -}; - -static struct platform_device myboard_i2cmux = { - .name = "i2c-mux-gpio", - .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-mux-gpio driver will do the work for you, -including deferred probing if the GPIO chip isn't immediately -available. - -Device Registration -------------------- - -When registering your i2c-mux-gpio 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. |