[PATCH v4 1/7] dt-bindings: document devicetree bindings for mux-controllers and mux-gpio

[Peter Rosin <peda@axentia.se>]

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 .../devicetree/bindings/misc/mux-controller.txt    | 106 +++++++++++++++++++++
 .../devicetree/bindings/misc/mux-gpio.txt          |  78 +++++++++++++++
 MAINTAINERS                                        |   5 +
 3 files changed, 189 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/misc/mux-controller.txt
 create mode 100644 Documentation/devicetree/bindings/misc/mux-gpio.txt

diff --git a/Documentation/devicetree/bindings/misc/mux-controller.txt b/Documentation/devicetree/bindings/misc/mux-controller.txt
new file mode 100644
index 000000000000..8e0733f60a37
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/mux-controller.txt
@@ -0,0 +1,106 @@
+Common multiplexer controller bindings
+
+A mux controller will have one, or several, consumer devices that uses the
+mux controller. Thus, a mux controller can possibly control several
+parallel multiplexers. If there are several consumer devices, the node for
+a mux controller will have one child node for each consumer of the multiplexer
+controller. If there is only one consumer of the mux controller, the mux
+controller node can be the child (with node name 'mux-controller') of the
+consumer node.
+
+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.
+
+Example:
+
+	/*
+	 * One consumer of a 2-way multiplexer controller by one GPIO-line,
+	 * with the multiplexer controller as a child node.
+	 */
+	adc-mux {
+		compatible = "iio-mux";
+		io-channels = <&adc 0>;
+		io-channel-names = "parent";
+
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		mux-controller {
+			compatible = "mux-gpio";
+
+			mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>;
+		};
+
+		sync-1@0 {
+			reg = <0>;
+		};
+
+		in@1 {
+			reg = <1>;
+		};
+	};
+
+	/*
+	 * 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 {
+		compatible = "mux-gpio";
+
+		mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>,
+			    <&pioA 1 GPIO_ACTIVE_HIGH>;
+
+		adc-mux {
+			compatible = "iio-mux";
+			io-channels = <&adc 0>;
+			io-channel-names = "parent";
+
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			sync-1@0 {
+				reg = <0>;
+			};
+
+			in@1 {
+				reg = <1>;
+			};
+
+			out@2 {
+				reg = <2>;
+			};
+
+			sync-2@3 {
+				reg = <3>;
+			};
+		};
+
+		i2c-mux {
+			compatible = "i2c-mux-simple,mux-locked";
+			i2c-parent = <&i2c1>;
+
+			#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 {
+					/* ... */
+				};
+			};
+		};
+	};
diff --git a/Documentation/devicetree/bindings/misc/mux-gpio.txt b/Documentation/devicetree/bindings/misc/mux-gpio.txt
new file mode 100644
index 000000000000..23b87913f4b3
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/mux-gpio.txt
@@ -0,0 +1,78 @@
+GPIO-based multiplexer controller bindings
+
+Define what GPIO pins are used to control a multiplexer. Or several
+multiplexers, if the same pins control more than one multiplexer.
+
+Required properties:
+- compatible : "mux-gpio"
+- mux-gpios : list of gpios used to control the multiplexer, least
+	      significant bit first.
+* Standard mux-controller bindings as decribed in mux-controller.txt
+
+Optional properties:
+- idle-state : if present, the state the mux will have when idle.
+
+The multiplexer state is defined as the number represented by the
+multiplexer GPIO pins, where the first pin is the least significant
+bit. And active pin is a binary 1, an inactive pin is a binary 0.
+
+Example:
+	mux {
+		compatible = "mux-gpio";
+
+		mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>,
+			    <&pioA 1 GPIO_ACTIVE_HIGH>;
+
+		adc {
+			compatible = "iio-mux";
+			io-channels = <&adc 0>;
+			io-channel-names = "parent";
+
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			sync-1@0 {
+				reg = <0>;
+			};
+
+			in@1 {
+				reg = <1>;
+			};
+
+			out@2 {
+				reg = <2>;
+			};
+
+			sync-2@3 {
+				reg = <3>;
+			};
+		};
+
+		i2c-mux {
+			compatible = "i2c-mux-simple,mux-locked";
+			i2c-parent = <&i2c1>;
+
+			#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 {
+					/* ... */
+				};
+			};
+		};
+	};
diff --git a/MAINTAINERS b/MAINTAINERS
index 4ebcd8df29d2..35869ed0a50e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8402,6 +8402,11 @@ S:	Orphan
 F:	drivers/mmc/host/mmc_spi.c
 F:	include/linux/spi/mmc_spi.h
 
+MULTIPLEXER SUBSYSTEM
+M:	Peter Rosin <peda@axentia.se>
+S:	Maintained
+F:	Documentation/devicetree/bindings/misc/mux-*
+
 MULTISOUND SOUND DRIVER
 M:	Andrew Veliath <andrewtv@usa.net>
 S:	Maintained
-- 
2.1.4