[alsa-devel] [PATCH 1/7] MFD: add bindings for STM32 DFSDM driver

[Arnaud Pouliquen]

Hello Rob,

Thanks for the review,
FYI This patch-set has to be abandoned to be redesigned without MFD driver.
Anyway i will take into account your remarks in my redesign.

I just added a comment below to explain CLKOUT.

Regards Arnaud


On 01/27/2017 09:53 PM, Rob Herring wrote:
> 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 at 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?

CLKOUT can be outputted to clock SPI interfaces (master mode) or extern
ADC. This CLKOUT is common for the 8 instances of the SPIs of the DFSDM.
CLKOUT frequency is computed based on an internal division of the
"dfsdm_clk" or "audio_clk".

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