dt-bindings: add mmio-based syscon mux controller DT bindings
This adds device tree binding documentation for mmio-based syscon
multiplexers controlled by a bitfields in a syscon register range.
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/Documentation/devicetree/bindings/mux/mmio-mux.txt b/Documentation/devicetree/bindings/mux/mmio-mux.txt
new file mode 100644
index 0000000..a9bfb4d
--- /dev/null
+++ b/Documentation/devicetree/bindings/mux/mmio-mux.txt
@@ -0,0 +1,60 @@
+MMIO register bitfield-based multiplexer controller bindings
+
+Define register bitfields to be used to control multiplexers. The parent
+device tree node must be a syscon node to provide register access.
+
+Required properties:
+- compatible : "mmio-mux"
+- #mux-control-cells : <1>
+- mux-reg-masks : an array of register offset and pre-shifted bitfield mask
+ pairs, each describing a single mux control.
+* Standard mux-controller bindings as decribed in mux-controller.txt
+
+Optional properties:
+- idle-states : if present, the state the muxes will have when idle. The
+ special state MUX_IDLE_AS_IS is the default.
+
+The multiplexer state of each multiplexer is defined as the value of the
+bitfield described by the corresponding register offset and bitfield mask pair
+in the mux-reg-masks array, accessed through the parent syscon.
+
+Example:
+
+ syscon {
+ compatible = "syscon";
+
+ mux: mux-controller {
+ compatible = "mmio-mux";
+ #mux-control-cells = <1>;
+
+ mux-reg-masks = <0x3 0x30>, /* 0: reg 0x3, bits 5:4 */
+ <0x3 0x40>, /* 1: reg 0x3, bit 6 */
+ idle-states = <MUX_IDLE_AS_IS>, <0>;
+ };
+ };
+
+ video-mux {
+ compatible = "video-mux";
+ mux-controls = <&mux 0>;
+
+ ports {
+ /* inputs 0..3 */
+ port@0 {
+ reg = <0>;
+ };
+ port@1 {
+ reg = <1>;
+ };
+ port@2 {
+ reg = <2>;
+ };
+ port@3 {
+ reg = <3>;
+ };
+
+ /* output */
+ port@4 {
+ reg = <4>;
+ };
+ };
+ };