i2c: Add generic I2C multiplexer using GPIO API

Add an i2c mux driver providing access to i2c bus segments using a
hardware MUX sitting on a master bus and controlled through gpio pins.

E.G. something like:

  ----------              ----------  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.

Signed-off-by: Peter Korsgaard <peter.korsgaard@barco.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
index 4d91d80bfd23..90b7a0163899 100644
--- a/drivers/i2c/muxes/Kconfig
+++ b/drivers/i2c/muxes/Kconfig
@@ -5,6 +5,18 @@
 menu "Multiplexer I2C Chip support"
         depends on I2C_MUX
 
+config I2C_MUX_GPIO
+        tristate "GPIO-based I2C multiplexer"
+        depends on GENERIC_GPIO
+        help
+          If you say yes to this option, support will be included for a
+          GPIO based I2C multiplexer. This driver provides access to
+          I2C busses connected through a MUX, which is controlled
+          through GPIO pins.
+
+          This driver can also be built as a module.  If so, the module
+          will be called gpio-i2cmux.
+
 config I2C_MUX_PCA9541
         tristate "NXP PCA9541 I2C Master Selector"
         depends on EXPERIMENTAL