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>

1 files changed, 63 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/sound/st,stm32-adfsdm.txt b/Documentation/devicetree/bindings/sound/st,stm32-adfsdm.txt
new file mode 100644
index 000000000000..864f5b00b031
--- /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>;
+                        };
+                };
+        };