From bc45449b1444611d68466ae7f45f235420d79019 Mon Sep 17 00:00:00 2001 From: David Daney Date: Thu, 12 Apr 2012 14:14:23 -0700 Subject: i2c/of: Automatically populate i2c mux busses from device tree data. For 'normal' i2c bus drivers, we can call of_i2c_register_devices() and have the device tree framework automatically populate the bus with the devices specified in the device tree. This patch adds a common code to the i2c mux framework to have the mux sub-busses be populated by the of_i2c_register_devices() too. If the mux device has an of_node, we populate the sub-bus' of_node so that the subsequent call to of_i2c_register_devices() will find the corresponding devices. It seemed better to put this logic in i2c_add_mux_adapter() rather than the individual mux drivers, as they will all probably want to do the same thing. Signed-off-by: David Daney Acked-by: Stephen Warren Tested-by: Lars-Peter Clausen [wsa: removed superfluous ret-variable and fixed a typo in a comment] Signed-off-by: Wolfram Sang --- Documentation/devicetree/bindings/i2c/mux.txt | 60 +++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) create mode 100644 Documentation/devicetree/bindings/i2c/mux.txt (limited to 'Documentation') diff --git a/Documentation/devicetree/bindings/i2c/mux.txt b/Documentation/devicetree/bindings/i2c/mux.txt new file mode 100644 index 000000000000..af84cce5cd7b --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/mux.txt @@ -0,0 +1,60 @@ +Common i2c bus multiplexer/switch properties. + +An i2c bus multiplexer/switch will have several child busses that are +numbered uniquely in a device dependent manner. The nodes for an i2c bus +multiplexer/switch will have one child node for each child +bus. + +Required properties: +- #address-cells = <1>; +- #size-cells = <0>; + +Required properties for child nodes: +- #address-cells = <1>; +- #size-cells = <0>; +- reg : The sub-bus number. + +Optional properties for child nodes: +- Other properties specific to the multiplexer/switch hardware. +- Child nodes conforming to i2c bus binding + + +Example : + + /* + An NXP pca9548 8 channel I2C multiplexer at address 0x70 + with two NXP pca8574 GPIO expanders attached, one each to + ports 3 and 4. + */ + + mux@70 { + compatible = "nxp,pca9548"; + reg = <0x70>; + #address-cells = <1>; + #size-cells = <0>; + + i2c@3 { + #address-cells = <1>; + #size-cells = <0>; + reg = <3>; + + gpio1: gpio@38 { + compatible = "nxp,pca8574"; + reg = <0x38>; + #gpio-cells = <2>; + gpio-controller; + }; + }; + i2c@4 { + #address-cells = <1>; + #size-cells = <0>; + reg = <4>; + + gpio2: gpio@38 { + compatible = "nxp,pca8574"; + reg = <0x38>; + #gpio-cells = <2>; + gpio-controller; + }; + }; + }; -- cgit