Linux kernel module for dynamicaly adding/removing bitbanged I²C hosts.
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i2c-gpio-param.c

README.md

i2c-gpio-param

Linux kernel module for adding GPIO bitbanged I²C host device. It uses i2c-gpio module but adds a way to dynamicaly add and remove busses when kernel is load and using sysfs interface. It is designed for and tested on RaspberyPi but it should work (with possible minor changes like pin_blacklist) on any other devices.

Installation

  1. Ensure that you have CONFIG_I2c_GPIO enabled in your kernel.
  2. Modify KDIR variable in Makefile to point to your kernel sources.
  3. In case of a crosscompilation, pass ARCH and CROSS_COMPILE options to make command. For example:

make ARCH=arm CROSS_COMPILE=arm-bcm2708-linux-gnueabi-

  1. Load resulting i2c-gpio-param.ko module.

Usage

Linux kernel module for adding GPIO bitbanged I²C host device.

It accepts following parameters:

  • busid (default 7) - I²C bus id (will create i2c-busid device)
  • sda (default 0) - GPIO pin number to be used as SDA
  • scl (default 1) - GPIO pin number to be used as SCL
  • udelay - SCL frequency is (500 / udelay)
  • timeout - clock streaching timeout
  • sda_od (bool) - SDA is configured as open drain
  • scl_od (bool) - SCL is configured as open drain
  • scl_oo (bool) - SCL output drivers cannot be turned of (no clock stretching)

You can add additional i2c-gpio busses or remove existing ones with sysfs interface:

  • /sys/class/i2c-gpio/add_bus accepts following space delimited integer arguments:

    busid ada scl [udelay] [timeout] [sda_od] [scl_od] [scl_oo]

  • /sys/class/i2c-gpio/remove_bus accepts one integer argument - busid

Example:

echo 5 2 3 > /sys/class/i2c-gpio/add_bus

echo 5 > /sys/class/i2c-gpio/remove_bus