ASoC: add bindings for stm32 DFSDM filter

Add bindings that describes audio settings to support
Digital Filter for pulse density modulation(PDM) microphone.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/Documentation/devicetree/bindings/sound/st,stm32-adfsdm.txt b/Documentation/devicetree/bindings/sound/st,stm32-adfsdm.txt
new file mode 100644 (file)
index 0000000..864f5b0
--- /dev/null
+++ b/Documentation/devicetree/bindings/sound/st,stm32-adfsdm.txt
@@ -0,0 +1,63 @@
+STMicroelectronics Audio Digital Filter Sigma Delta modulators(DFSDM)
+
+The DFSDM allows PDM microphones capture through SPI interface. The Audio
+interface is seems as a sub block of the DFSDM device.
+For details on DFSDM bindings refer to ../iio/adc/st,stm32-dfsdm-adc.txt
+
+Required properties:
+  - compatible: "st,stm32h7-dfsdm-dai".
+
+  - #sound-dai-cells : Must be equal to 0
+
+  - io-channels : phandle to iio dfsdm instance node.
+
+Example of a sound card using audio DFSDM node.
+
+       sound_card {
+               compatible = "audio-graph-card";
+
+               dais = <&cpu_port>;
+       };
+
+       dfsdm: dfsdm@40017000 {
+               compatible = "st,stm32h7-dfsdm";
+               reg = <0x40017000 0x400>;
+               clocks = <&rcc DFSDM1_CK>;
+               clock-names = "dfsdm";
+               #interrupt-cells = <1>;
+               #address-cells = <1>;
+               #size-cells = <0>;
+
+               dfsdm_adc0: filter@0 {
+                       compatible = "st,stm32-dfsdm-dmic";
+                       reg = <0>;
+                       interrupts = <110>;
+                       dmas = <&dmamux1 101 0x400 0x00>;
+                       dma-names = "rx";
+                       st,adc-channels = <1>;
+                       st,adc-channel-names = "dmic0";
+                       st,adc-channel-types = "SPI_R";
+                       st,adc-channel-clk-src = "CLKOUT";
+                       st,filter-order = <5>;
+
+                       dfsdm_dai0: dfsdm-dai {
+                               compatible = "st,stm32h7-dfsdm-dai";
+                               #sound-dai-cells = <0>;
+                               io-channels = <&dfsdm_adc0 0>;
+                               cpu_port: port {
+                               dfsdm_endpoint: endpoint {
+                                       remote-endpoint = <&dmic0_endpoint>;
+                               };
+                       };
+               };
+       };
+
+       dmic0: dmic@0 {
+               compatible = "dmic-codec";
+               #sound-dai-cells = <0>;
+               port {
+                       dmic0_endpoint: endpoint {
+                               remote-endpoint = <&dfsdm_endpoint>;
+                       };
+               };
+       };