dm: i2c: Add support for multiplexed I2C buses
Add a new I2C_MUX uclass. Devices in this class can multiplex between
several I2C buses, selecting them one at a time for use by the system.
The multiplexing mechanism is left to the driver to decide - it may be
controlled by GPIOs, for example.
The uclass supports only two methods: select() and deselect().
The current mux state is expected to be stored in the mux itself since
it is the only thing that knows how to make things work. The mux can
record the current state and then avoid switching unless it is necessary.
So select() can be skipped if the mux is already in the correct state.
Also deselect() can be made a nop if required.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 86fb36b..caee3d8 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -73,3 +73,5 @@
help
Support for UniPhier FIFO-builtin I2C controller driver.
This I2C controller is used on PH1-Pro4 or newer UniPhier SoCs.
+
+source "drivers/i2c/muxes/Kconfig"