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93 lines
2.8 KiB
93 lines
2.8 KiB
Pinctrl-based I2C Bus Mux |
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This binding describes an I2C bus multiplexer that uses pin multiplexing to |
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route the I2C signals, and represents the pin multiplexing configuration |
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using the pinctrl device tree bindings. |
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+-----+ +-----+ |
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| dev | | dev | |
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+------------------------+ +-----+ +-----+ |
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| SoC | | | |
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| /----|------+--------+ |
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| +---+ +------+ | child bus A, on first set of pins |
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| |I2C|---|Pinmux| | |
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| +---+ +------+ | child bus B, on second set of pins |
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| \----|------+--------+--------+ |
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| | | | | |
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+------------------------+ +-----+ +-----+ +-----+ |
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| dev | | dev | | dev | |
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+-----+ +-----+ +-----+ |
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Required properties: |
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- compatible: i2c-mux-pinctrl |
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- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side |
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port is connected to. |
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Also required are: |
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* Standard pinctrl properties that specify the pin mux state for each child |
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bus. See ../pinctrl/pinctrl-bindings.txt. |
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* Standard I2C mux properties. See i2c-mux.txt in this directory. |
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* I2C child bus nodes. See i2c-mux.txt in this directory. |
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For each named state defined in the pinctrl-names property, an I2C child bus |
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will be created. I2C child bus numbers are assigned based on the index into |
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the pinctrl-names property. |
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The only exception is that no bus will be created for a state named "idle". If |
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such a state is defined, it must be the last entry in pinctrl-names. For |
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example: |
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pinctrl-names = "ddc", "pta", "idle" -> ddc = bus 0, pta = bus 1 |
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pinctrl-names = "ddc", "idle", "pta" -> Invalid ("idle" not last) |
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pinctrl-names = "idle", "ddc", "pta" -> Invalid ("idle" not last) |
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Whenever an access is made to a device on a child bus, the relevant pinctrl |
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state will be programmed into hardware. |
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If an idle state is defined, whenever an access is not being made to a device |
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on a child bus, the idle pinctrl state will be programmed into hardware. |
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If an idle state is not defined, the most recently used pinctrl state will be |
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left programmed into hardware whenever no access is being made of a device on |
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a child bus. |
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Example: |
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i2cmux { |
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compatible = "i2c-mux-pinctrl"; |
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#address-cells = <1>; |
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#size-cells = <0>; |
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i2c-parent = <&i2c1>; |
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pinctrl-names = "ddc", "pta", "idle"; |
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pinctrl-0 = <&state_i2cmux_ddc>; |
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pinctrl-1 = <&state_i2cmux_pta>; |
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pinctrl-2 = <&state_i2cmux_idle>; |
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i2c@0 { |
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reg = <0>; |
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#address-cells = <1>; |
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#size-cells = <0>; |
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eeprom { |
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compatible = "eeprom"; |
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reg = <0x50>; |
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}; |
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}; |
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i2c@1 { |
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reg = <1>; |
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#address-cells = <1>; |
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#size-cells = <0>; |
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eeprom { |
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compatible = "eeprom"; |
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reg = <0x50>; |
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}; |
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}; |
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}; |
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