This patch adds documentation of device tree bindings for the STM32 DFSDM ASoC driver.
Signed-off-by: Arnaud Pouliquen arnaud.pouliquen@st.com --- .../devicetree/bindings/sound/st,sm32-adfsdm.txt | 84 ++++++++++++++++++++++ 1 file changed, 84 insertions(+) create mode 100644 Documentation/devicetree/bindings/sound/st,sm32-adfsdm.txt
diff --git a/Documentation/devicetree/bindings/sound/st,sm32-adfsdm.txt b/Documentation/devicetree/bindings/sound/st,sm32-adfsdm.txt new file mode 100644 index 0000000..a1d27b8 --- /dev/null +++ b/Documentation/devicetree/bindings/sound/st,sm32-adfsdm.txt @@ -0,0 +1,84 @@ +STMicroelectronics STM32 ADFSDM ASoC DAI device driver. + +STM32 ADFSDM ASoC is a sigma delta audio interface for digital microphone. +It has to be declared in device-tree as a subnode of the DFSDM mfd node. + +It offers possibility to record several mono microphones, with an option to +synchronize all microphones on a main one (that must be piped to filter 0) +Audio interface can be exposed through the generic ASoC simple card. + +2 Dmics can be connected on one SPI interface instance n. +Convention is that the DMIC that strobes data on rising edge is connected to the +corresponding DFSDM channel n; while the Dmic that strobes data on falling edge +is connected to the channel n-1. Simple card property "bitclock-inversion = <1>" +is used to specify that microphone strobes data on falling edge. + +SPI interface allows to be scheduled by an external SPI clock. To use it +simple card properties "bitclock-master = <&codec>" and "system-clock-frequency" +have to be defined in dai-link node. + +Required properties: +- compatible: Must be "st,stm32-dfsdm-audio", +- reg: Specifies the DFSDM filter instance. +- interrupts: DFSDM filter instance interrupt line. +- dma: DMA controller phandle and DMA request line associated to the + filter instance ( specified by the field "reg") +- dma-names: must be "rx" + +- st,input-id: Id of the SPI/Manchester interface used. +- st,dai-filter-order: SinC filter order from 0 to 5. + 0: FastSinC + [1-5]: order 1 to 5. + For audio purpose it is recommended to use order 3 to 5. + +Optional properties: + - st,dai0-synchronized: Set to 1 to synchronize DAI with DFSDM instance 0. + +Exemple of a card with 2 Dmics synchronized and connected on SPI interface 1. + + dfsdm: dfsdm@4400D000 { + dai_dfsdm0: dfsdm-audio@0 { + compatible = "st,stm32-dfsdm-audio"; + #sound-dai-cells = <0>; + reg = <0>; + dmas = <&dmamux1 101 0x400 0x00>; + dma-names = "rx"; + st,input-id = <0>; + st,dai-filter-order = <5>; + }; + dai_dfsdm1: dfsdm-audio@1 { + compatible = "st,stm32-dfsdm-audio"; + #sound-dai-cells = <0>; + reg = <0>; + dmas = <&dmamux1 102 0x400 0x00>; + dma-names = "rx"; + st,input-id = <0>; + st,dai0-synchronized = <1>; + st,dai-filter-order = <5>; + }; + }; + sound_dfsdm_pdm { + compatible = "simple-audio-card"; + simple-audio-card,name = "dfsdm_pdm"; + status = "okay"; + + dfsdm0_mic0: simple-audio-card,dai-link@0 { + format = "pdm"; + cpu { + sound-dai = <&dai_dfsdm0>; + }; + dmic0_codec: codec { + sound-dai = <&dmic0>; + }; + }; + dfsdm0_mic1: simple-audio-card,dai-link@1 { + format = "pdm"; + bitclock-inversion = <1>; + cpu { + sound-dai = <&dai_dfsdm1>; + }; + codec { + sound-dai = <&dmic1>; + }; + }; + };