diff options
Diffstat (limited to 'Documentation/devicetree/bindings/mux/mux-controller.txt')
-rw-r--r-- | Documentation/devicetree/bindings/mux/mux-controller.txt | 157 |
1 files changed, 0 insertions, 157 deletions
diff --git a/Documentation/devicetree/bindings/mux/mux-controller.txt b/Documentation/devicetree/bindings/mux/mux-controller.txt deleted file mode 100644 index 4f47e4bd2fa0..000000000000 --- a/Documentation/devicetree/bindings/mux/mux-controller.txt +++ /dev/null @@ -1,157 +0,0 @@ -Common multiplexer controller bindings -====================================== - -A multiplexer (or mux) controller will have one, or several, consumer devices -that uses the mux controller. Thus, a mux controller can possibly control -several parallel multiplexers. Presumably there will be at least one -multiplexer needed by each consumer, but a single mux controller can of course -control several multiplexers for a single consumer. - -A mux controller provides a number of states to its consumers, and the state -space is a simple zero-based enumeration. I.e. 0-1 for a 2-way multiplexer, -0-7 for an 8-way multiplexer, etc. - - -Consumers ---------- - -Mux controller consumers should specify a list of mux controllers that they -want to use with a property containing a 'mux-ctrl-list': - - mux-ctrl-list ::= <single-mux-ctrl> [mux-ctrl-list] - single-mux-ctrl ::= <mux-ctrl-phandle> [mux-ctrl-specifier] - mux-ctrl-phandle : phandle to mux controller node - mux-ctrl-specifier : array of #mux-control-cells specifying the - given mux controller (controller specific) - -Mux controller properties should be named "mux-controls". The exact meaning of -each mux controller property must be documented in the device tree binding for -each consumer. An optional property "mux-control-names" may contain a list of -strings to label each of the mux controllers listed in the "mux-controls" -property. - -Drivers for devices that use more than a single mux controller can use the -"mux-control-names" property to map the name of the requested mux controller -to an index into the list given by the "mux-controls" property. - -mux-ctrl-specifier typically encodes the chip-relative mux controller number. -If the mux controller chip only provides a single mux controller, the -mux-ctrl-specifier can typically be left out. - -Example: - - /* One consumer of a 2-way mux controller (one GPIO-line) */ - mux: mux-controller { - compatible = "gpio-mux"; - #mux-control-cells = <0>; - - mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>; - }; - - adc-mux { - compatible = "io-channel-mux"; - io-channels = <&adc 0>; - io-channel-names = "parent"; - - mux-controls = <&mux>; - mux-control-names = "adc"; - - channels = "sync", "in"; - }; - -Note that in the example above, specifying the "mux-control-names" is redundant -because there is only one mux controller in the list. However, if the driver -for the consumer node in fact asks for a named mux controller, that name is of -course still required. - - /* - * Two consumers (one for an ADC line and one for an i2c bus) of - * parallel 4-way multiplexers controlled by the same two GPIO-lines. - */ - mux: mux-controller { - compatible = "gpio-mux"; - #mux-control-cells = <0>; - - mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>, - <&pioA 1 GPIO_ACTIVE_HIGH>; - }; - - adc-mux { - compatible = "io-channel-mux"; - io-channels = <&adc 0>; - io-channel-names = "parent"; - - mux-controls = <&mux>; - - channels = "sync-1", "in", "out", "sync-2"; - }; - - i2c-mux { - compatible = "i2c-mux"; - i2c-parent = <&i2c1>; - - mux-controls = <&mux>; - - #address-cells = <1>; - #size-cells = <0>; - - i2c@0 { - reg = <0>; - #address-cells = <1>; - #size-cells = <0>; - - ssd1307: oled@3c { - /* ... */ - }; - }; - - i2c@3 { - reg = <3>; - #address-cells = <1>; - #size-cells = <0>; - - pca9555: pca9555@20 { - /* ... */ - }; - }; - }; - - -Mux controller nodes --------------------- - -Mux controller nodes must specify the number of cells used for the -specifier using the '#mux-control-cells' property. - -Optionally, mux controller nodes can also specify the state the mux should -have when it is idle. The idle-state property is used for this. If the -idle-state is not present, the mux controller is typically left as is when -it is idle. For multiplexer chips that expose several mux controllers, the -idle-state property is an array with one idle state for each mux controller. - -The special value (-1) may be used to indicate that the mux should be left -as is when it is idle. This is the default, but can still be useful for -mux controller chips with more than one mux controller, particularly when -there is a need to "step past" a mux controller and set some other idle -state for a mux controller with a higher index. - -Some mux controllers have the ability to disconnect the input/output of the -multiplexer. Using this disconnected high-impedance state as the idle state -is indicated with idle state (-2). - -These constants are available in - - #include <dt-bindings/mux/mux.h> - -as MUX_IDLE_AS_IS (-1) and MUX_IDLE_DISCONNECT (-2). - -An example mux controller node look like this (the adg972a chip is a triple -4-way multiplexer): - - mux: mux-controller@50 { - compatible = "adi,adg792a"; - reg = <0x50>; - #mux-control-cells = <1>; - - idle-state = <MUX_IDLE_DISCONNECT MUX_IDLE_AS_IS 2>; - }; |