Re: [PATCH 3/7] IIO: add bindings for STM32 DFSDM ADC driver

[Jonathan Cameron <jic23@kernel.org>]

On 23/01/17 16:32, Arnaud Pouliquen wrote:
> This patch adds documentation of device tree bindings for the
> STM32 DFSDM ADC.
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Trivial bits inline.
> ---
>  .../bindings/iio/adc/st,stm32-dfsdm-adc.txt        | 60 ++++++++++++++++++++++
>  1 file changed, 60 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.txt 
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.txt  b/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.txt 
> new file mode 100644
> index 0000000..c156bcb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.txt 	
> @@ -0,0 +1,60 @@
> +STMicroelectronics STM32 DFSDM ADC device driver
> +
> +STM32 DFSDM ADC is a sigma delta analog-to-digital converter.
> +It has to be declared in device-tree as a subnode of the DFSDM mfd node.
> +
> +It has several multiplexed input channels. Conversions can be performed
> +in single, scan or discontinuous mode. Conversions can be launched in software
> +or using hardware triggers.
> +Each instance of the driver uses one filter instance handle by the DFSDM mfd
> +driver.
> +
> +DFSDM also offers extra features:
> +-The analog watchdog feature allows the application to detect if the
> + input voltage goes beyond the user-defined, higher or lower thresholds.
> +-The short circuit detection allows allows the application to detect if the
> + input is in CC.
> +-The clock absence detection allows application to detect if SPI input is clocked.
> +
> +Required properties:
> +- compatible:	Must be "st,stm32-dfsdm-adc".
> +- reg:		Specifies the DFSDM filter instance.
> +- #io-channel-cells = <1>: See the IIO bindings section "IIO consumers".
> +- st,adc-channels:	List of single-ended channels muxed for this ADC.
> +- st,adc-channel-names:	List of single-ended channels Name.
> +
> +Optional properties:
> +- st,adc-channel-types:	Single-ended channel input type. Default value is 0.
> +			- 0: SPI with data on rising edge (default)
> +			- 1: SPI with data on falling edge
This is an element that can be described without magic numbers so I'd
prefer that you do so.

Also spell check edage -> edge.

> +			- 2: manchester codec, rising edage = logic 0
> +			- 3: manchester codec, rising edage = logic 1
> +- st,adc-channel-clk-src: Conversion clock source. default value is 1.
> +			  - 0: External SPI clocl (CLKIN x)
> +			  - 1: internal SPI clock (CLKOUT) (default)
> +			  - 2: internal SPI clock divided by 2 (falling edge).
> +			  - 2: internal SPI clock divided by 2 (rising edge).
3?
> +- st,adc-alt-channel: 	  must be defined if Two ADCs 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.
? Two data inputs with shared clock?
> +
> +Example:
> +	dfsdm: dfsdm@4400D000 {
> +		iio_dfsdm0: iio-dfsdm@0 {
> +			compatible = "st,stm32-dfsdm-adc";
> +			#io-channel-cells = <1>;
> +			reg = <0>;
> +			st,adc-channels = <1>;
> +			st,adc-channel-names = "in0";
> +		};
> +		iio_dfsdm1: iio-dfsdm@1 {
> +			compatible = "st,stm32-dfsdm-adc";
> +			#io-channel-cells = <1>;
> +			reg = <1>;
> +			st,adc-channels = <1>;
> +			st,adc-channel-names = "in1";
> +			st,adc-channel-types = <1>;
> +			st,adc-alt-channel = <1>;
> +		};
> +	};
>