Re: [PATCH 1/7] MFD: add bindings for STM32 DFSDM driver

[Rob Herring <robh@kernel.org>]

On Mon, Jan 23, 2017 at 05:32:19PM +0100, Arnaud Pouliquen wrote:
> Add bindings information for STM32 Digital Filter for Sigma Delta modulators MFD driver
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
> ---
>  .../devicetree/bindings/mfd/stm32-dfsdm.txt        | 68 ++++++++++++++++++++++
>  1 file changed, 68 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mfd/stm32-dfsdm.txt
> 
> diff --git a/Documentation/devicetree/bindings/mfd/stm32-dfsdm.txt b/Documentation/devicetree/bindings/mfd/stm32-dfsdm.txt
> new file mode 100644
> index 0000000..e0b45ee
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/stm32-dfsdm.txt
> @@ -0,0 +1,68 @@
> +STMicroelectronics STM32 Digital Filter for Sigma Delta Modulator (DFSDM)
> +ulti-function device.
> +
> +The STM32 DFSDM device is a multifunction device that handles the DFSDM IP.
> +
> +The DFSDM IP allows to add processing on Sigma Delta ADC based on SinC filters.
> +For this, a pool of m filters can be connected to a pool of n channels.
> +For STM32H7 : m = 4, n = 8.
> +
> +Each channel n is assigned to the SPI or Manchester interface n or n + 1.
> +Channels 0 to 2 can also be connected to ADC IP instance 1 to 3.
> +Filtering result is stored in a left aligned register, with 8 LSB reserved for
> +the input channel ID.
> +
> +Each filter instance supports two contexts to manage conversions, each one has
> +its own configurable sequence and trigger:
> +- regular conversion: used for single or continuous conversion.
> +- injected conversions: used for triggered conversion.
> +
> +Interfaces supported:
> +- sigma delta ADCs trough IIO framework.
> +- PDM microphones through ASoC framework.

Bindings describe h/w, not Linux subsystems.

> +
> +Required properties:
> +- compatible:	Must be "st,stm32h7-dfsdm".
> +- reg:		Specifies the DFSDM block register address and length.
> +- interrupts:	IRQ lines connected to each DFSDM filter instance.
> +- clocks:	IP and serial interfaces clocking. Should be set according
> +		to rcc clock ID and "clock-names".
> +- clock-names:	Input clock name "dfsdm_clk" must be defined,
> +		"audio_clk" is optional. If defined CLKOUT is based on the audio
> +		clock, else "dfsdm_clk" is used.

_clk is redundant.

> +
> +Optional properties:
> +- st,clkout-freq: clkout clock frequency (Hz).This clock must be set according
> +		  to "clock" property. Frequency must be a multiple of the rcc
> +		  clock frequency. If not, clkout frequency will not be
> +		  accurate.

What is CLKOUT connected to and will you need to describe that in DT?

> +- pinctrl-names:  set to "default".
> +- pinctrl-0:	  List of phandles pointing to pin configuration nodes for DFSDM
> +		  module.
> +		  For Pinctrl properties see ../pinctrl/pinctrl-bindings.txt
> +Example :
> +	dfsdm: dfsdm@4400D000 {
> +		compatible = "st,stm32h7-dfsdm";
> +		reg = <0x40017000 0x400>;
> +		interrupts = <110>, <111>, <112>, <113>;
> +		clocks = <&timer_clk>;
> +		clock-names = "dfsdm_clk";
> +		pinctrl-0 = <&dfsdm_ch0 &dfsdm_ch1>;
> +		pinctrl-names = "default";
> +		st,clkout-freq = <2480000>;
> +
> +		iio_dfsdm0: iio-dfsdm@0 {

adc {

> +			compatible = "st,stm32-dfsdm-adc";
> +			#io-channel-cells = <1>;
> +			reg = <0>;
> +			status = "disabled";
> +		};
> +		dai_dfsdm0: dfsdm-audio@0 {

digital-mic {

> +			compatible = "st,stm32-dfsdm-audio";
> +			#sound-dai-cells = <0>;
> +			reg = <0>;

You can't have 2 children with the same unit address. Just drop reg and 
the unit address.

> +			dmas = <&dmamux1 101 0x400 0x00>;
> +			dma-names = "rx";
> +			status = "disabled";
> +		};
> +	};
> -- 
> 1.9.1
>