[PATCH 2/7] Documentation: DT: bindings: mfd: add documentation for Allwinner SoCs' GPADC MFD driver

[Maxime Ripard]

On Tue, Dec 20, 2016 at 11:27:04AM +0100, Quentin Schulz wrote:
> The Allwinner SoCs all have an ADC that can also act as a thermal sensor
> and sometimes as a touchscreen controller. If there is a touchscreen
> controller, the first four channels can be used either for the ADC or
> the touchscreen and the fifth channel is used for the thermal sensor.
> If there is not a touchscreen controller, the one and only channel is
> used for the thermal sensor.
> 
> The Allwinner SoCs already have an existing DT binding for the
> touchscreen controller and thermal sensor for the sun4i-ts input driver
> which does let the user use the ADC. To keep backward compatibility,
> this MFD driver re-uses the same bindings as the sun4i-ts input driver
> and will probe the required drivers to make the ADC and thermal sensor
> work.
> 
> This patch adds the binding documentation for the MFD driver of the
> Allwinner SoCs' GPADC.
> 
> Signed-off-by: Quentin Schulz <quentin.schulz at free-electrons.com>
> ---
>  .../devicetree/bindings/mfd/sun4i-gpadc.txt        | 47 ++++++++++++++++++++++
>  1 file changed, 47 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mfd/sun4i-gpadc.txt
> 
> diff --git a/Documentation/devicetree/bindings/mfd/sun4i-gpadc.txt b/Documentation/devicetree/bindings/mfd/sun4i-gpadc.txt
> new file mode 100644
> index 0000000..bc4b4f6
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/sun4i-gpadc.txt
> @@ -0,0 +1,47 @@
> +Allwinner SoCs' GPADC Device Tree bindings
> +------------------------------------------
> +
> +The Allwinner SoCs all have an ADC that can also act as a thermal sensor and
> +sometimes as a touchscreen controller. If there is a touchscreen controller, the
> +first four channels can be used either for the ADC or the touchscreen and the
> +fifth channel is used for the thermal sensor.
> +If there is not a touchscreen controller, the one and only channel is used for
> +the thermal sensor.
> +
> +Currently, the touchscreen controller does not have a driver using this ADC
> +driver. The touchscreen controller is currently driven only by
> +input/touchscreen/sun4i-ts.c which is absolutely incompatible with this driver.
> +
> +The Allwinner A10, A13 and A31 SoCs already have a DT binding for the
> +aforementioned input driver, thus this MFD driver matches the existing DT
> +binding (mfd/sun4i-gpadc.c).
> +To keep DT binding compatibility, the MFD replaces the sun4i-ts input driver and
> +probes required drivers (IIO GPADC driver (iio/adc/sun4i-gpadc-iio.c),
> +iio-hwmon and soon the touchscreen driver) without the need for a DT binding for
> +each driver.
> +
> +Required properties:
> + - compatible: one of:
> +	- "allwinner,sun4i-a10-ts",
> +	- "allwinner,sun5i-a13-ts",
> +	- "allwinner,sun6i-a31-ts"
> + - #thermal-sensor-cells = <0>;

Same thing here, we already have such a document, please amend it if
needed.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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