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+STMicroelectronics STM32 DFSDM ADC device driver
+
+
+STM32 DFSDM ADC is a sigma delta analog-to-digital converter dedicated to
+interface external sigma delta modulators to STM32 micro controllers.
+It is mainly targeted for:
+- Sigma delta modulators (motor control, metering...)
+- PDM microphones (audio digital microphone)
+
+It features up to 8 serial digital interfaces (SPI or Manchester) and
+up to 4 filters on stm32h7.
+
+Each child node match with a filter instance.
+
+Contents of a STM32 DFSDM root node:
+------------------------------------
+Required properties:
+- compatible: Should be "st,stm32h7-dfsdm".
+- reg: Offset and length of the DFSDM block register set.
+- clocks: IP and serial interfaces clocking. Should be set according
+ to rcc clock ID and "clock-names".
+- clock-names: Input clock name "dfsdm" must be defined,
+ "audio" is optional. If defined CLKOUT is based on the audio
+ clock, else "dfsdm" is used.
+- #interrupt-cells = <1>;
+- #address-cells = <1>;
+- #size-cells = <0>;
+
+Optional properties:
+- spi-max-frequency: Requested only for SPI master mode.
+ SPI clock OUT frequency (Hz). This clock must be set according
+ to "clock" property. Frequency must be a multiple of the rcc
+ clock frequency. If not, SPI CLKOUT frequency will not be
+ accurate.
+
+Contents of a STM32 DFSDM child nodes:
+--------------------------------------
+
+Required properties:
+- compatible: Must be:
+ "st,stm32-dfsdm-adc" for sigma delta ADCs
+ "st,stm32-dfsdm-dmic" for audio digital microphone.
+- reg: Specifies the DFSDM filter instance used.
+- interrupts: IRQ lines connected to each DFSDM filter instance.
+- st,adc-channels: List of single-ended channels muxed for this ADC.
+ valid values:
+ "st,stm32h7-dfsdm" compatibility: 0 to 7.
+- st,adc-channel-names: List of single-ended channel names.
+- st,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.
+- #io-channel-cells = <1>: See the IIO bindings section "IIO consumers".
+
+Required properties for "st,stm32-dfsdm-adc" compatibility:
+- io-channels: From common IIO binding. Used to pipe external sigma delta
+ modulator or internal ADC output to DFSDM channel.
+ This is not required for "st,stm32-dfsdm-pdm" compatibility as
+ PDM microphone is binded in Audio DT node.
+
+Required properties for "st,stm32-dfsdm-pdm" compatibility:
+- #sound-dai-cells: Must be set to 0.
+- dma: DMA controller phandle and DMA request line associated to the
+ filter instance (specified by the field "reg")
+- dma-names: Must be "rx"
+
+Optional properties:
+- st,adc-channel-types: Single-ended channel input type.
+ - "SPI_R": SPI with data on rising edge (default)
+ - "SPI_F": SPI with data on falling edge
+ - "MANCH_R": manchester codec, rising edge = logic 0
+ - "MANCH_F": manchester codec, falling edge = logic 1
+- st,adc-channel-clk-src: Conversion clock source.
+ - "CLKIN": external SPI clock (CLKIN x)
+ - "CLKOUT": internal SPI clock (CLKOUT) (default)
+ - "CLKOUT_F": internal SPI clock divided by 2 (falling edge).
+ - "CLKOUT_R": internal SPI clock divided by 2 (rising edge).
+
+- st,adc-alt-channel: Must be defined if two sigma delta modulator are
+ connected on same SPI input.
+ If not set, channel n is connected to SPI input n.
+ If set, channel n is connected to SPI input n + 1.
+
+- st,filter0-sync: Set to 1 to synchronize with DFSDM filter instance 0.
+ Used for multi microphones synchronization.
+
+Example of a sigma delta adc connected on DFSDM SPI port 0
+and a pdm microphone connected on DFSDM SPI port 1:
+
+ ads1202: simple_sd_adc@0 {
+ compatible = "ads1202";
+ #io-channel-cells = <1>;
+ };
+
+ 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-adc";
+ #io-channel-cells = <1>;
+ reg = <0>;
+ interrupts = <110>;
+ st,adc-channels = <0>;
+ st,adc-channel-names = "sd_adc0";
+ st,adc-channel-types = "SPI_F";
+ st,adc-channel-clk-src = "CLKOUT";
+ io-channels = <&ads1202 0>;
+ st,filter-order = <3>;
+ };
+ dfsdm_pdm1: filter@1 {
+ compatible = "st,stm32-dfsdm-dmic";
+ reg = <1>;
+ interrupts = <111>;
+ dmas = <&dmamux1 102 0x400 0x00>;
+ dma-names = "rx";
+ st,adc-channels = <1>;
+ st,adc-channel-names = "dmic1";
+ st,adc-channel-types = "SPI_R";
+ st,adc-channel-clk-src = "CLKOUT";
+ st,filter-order = <5>;
+ };
+ }