On Thu, Apr 13, 2017 at 05:48:11PM +0200, Philipp Zabel wrote:
> This adds device tree binding documentation for mmio-based syscon
> multiplexers controlled by a single bitfield in a syscon register
> range.
>
> Signed-off-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
> ---
> Documentation/devicetree/bindings/mux/mmio-mux.txt | 56 ++++++++++++++++++++++
> 1 file changed, 56 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/mux/mmio-mux.txt
>
> diff --git a/Documentation/devicetree/bindings/mux/mmio-mux.txt b/Documentation/devicetree/bindings/mux/mmio-mux.txt
> new file mode 100644
> index 0000000000000..11d96f5d98583
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mux/mmio-mux.txt
> @@ -0,0 +1,56 @@
> +MMIO bitfield-based multiplexer controller bindings
> +
> +Define a syscon bitfield to be used to control a multiplexer. The parent
> +device tree node must be a syscon node to provide register access.
> +
> +Required properties:
> +- compatible : "gpio-mux"
?
> +- reg : register base of the register containing the control bitfield
> +- bit-mask : bitmask of the control bitfield in the control register
> +- bit-shift : bit offset of the control bitfield in the control register
> +- #mux-control-cells : <0>
> +* 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
> + special state MUX_IDLE_AS_IS is the default.
> +
> +The multiplexer state is defined as the value of the bitfield described
> +by the reg, bit-mask, and bit-shift properties, accessed through the parent
> +syscon.
> +
> +Example:
> +
> + syscon {
> + compatible = "syscon";
> +
> + mux: mux-controller@3 {
> + compatible = "mmio-mux";
> + reg = <0x3>;
> + bit-mask = <0x1>;
> + bit-shift = <5>;
This pattern doesn't scale once you have multiple fields @ addr 3. I
also don't really think a node per register field in DT really scales.
I think the parent should be declared as a mux controller instead. You
could encode the mux addr and bit position in the mux cells.
> + #mux-control-cells = <0>;
> + };
> + };
> +
> + video-mux {
> + compatible = "video-mux";
> + mux-controls = <&mux>;
The mux binding was largely defined for a single control controling
multiple muxes. This doesn't really fit that, but I guess this is an
improvement over a custom syscon phandle.
> +
> + ports {
> + /* input 0 */
> + port@0 {
> + reg = <0>;
> + };
> +
> + /* input 1 */
> + port@1 {
> + reg = <1>;
> + };
> +
> + /* output */
> + port@2 {
> + reg = <2>;
> + };
> + };
> + };
> --
> 2.11.0
>
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
