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374f8436ff
Similar to the new optional 'i2c-bus' subnode from Jon Hunter, this adds an optional 'i2c-mux' subnode, for similar reasons. I.e. it is bad of the i2c mux core to assume that any subnode of an i2c mux device is a potential (when the 'reg' property matches) i2c-mux child bus, given that i2c mux devices might do more than mux i2c traffic. So, if an 'i2c-mux' subnode is present, dictate that all i2c-mux child buses exist beneath that subnode. Acked-by: Rob Herring <robh@kernel.org> Reviewed-by: Wolfram Sang <wsa@the-dreams.de> Signed-off-by: Peter Rosin <peda@axentia.se>
74 lines
1.8 KiB
Plaintext
74 lines
1.8 KiB
Plaintext
Common i2c bus multiplexer/switch properties.
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An i2c bus multiplexer/switch will have several child busses that are
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numbered uniquely in a device dependent manner. The nodes for an i2c bus
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multiplexer/switch will have one child node for each child bus.
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Optional properties:
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- #address-cells = <1>;
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This property is required is the i2c-mux child node does not exist.
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- #size-cells = <0>;
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This property is required is the i2c-mux child node does not exist.
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- i2c-mux
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For i2c multiplexers/switches that have child nodes that are a mixture
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of both i2c child busses and other child nodes, the 'i2c-mux' subnode
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can be used for populating the i2c child busses. If an 'i2c-mux'
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subnode is present, only subnodes of this will be considered as i2c
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child busses.
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Required properties for the i2c-mux child node:
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- #address-cells = <1>;
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- #size-cells = <0>;
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Required properties for i2c child bus nodes:
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- #address-cells = <1>;
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- #size-cells = <0>;
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- reg : The sub-bus number.
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Optional properties for i2c child bus nodes:
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- Other properties specific to the multiplexer/switch hardware.
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- Child nodes conforming to i2c bus binding
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Example :
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/*
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An NXP pca9548 8 channel I2C multiplexer at address 0x70
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with two NXP pca8574 GPIO expanders attached, one each to
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ports 3 and 4.
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*/
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mux@70 {
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compatible = "nxp,pca9548";
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reg = <0x70>;
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#address-cells = <1>;
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#size-cells = <0>;
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i2c@3 {
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#address-cells = <1>;
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#size-cells = <0>;
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reg = <3>;
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gpio1: gpio@38 {
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compatible = "nxp,pca8574";
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reg = <0x38>;
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#gpio-cells = <2>;
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gpio-controller;
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};
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};
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i2c@4 {
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#address-cells = <1>;
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#size-cells = <0>;
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reg = <4>;
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gpio2: gpio@38 {
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compatible = "nxp,pca8574";
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reg = <0x38>;
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#gpio-cells = <2>;
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gpio-controller;
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};
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};
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};
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