| Kernel driver i2c-gpio-mux |
| |
| Author: Peter Korsgaard <peter.korsgaard@barco.com> |
| |
| Description |
| ----------- |
| |
| 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.: |
| |
| ---------- ---------- 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-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/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/i2c-gpio-mux.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 gpio_i2cmux_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-gpio-mux", |
| .id = 0, |
| .dev = { |
| .platform_data = &myboard_i2cmux_data, |
| }, |
| }; |
