linux-kernel - Re: [PATCH v2 01/16] dt-bindings: update the Allwinner GPADC device tree binding for H3 & A83T

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Message-ID: <4188f487-6c9d-8f1e-25cc-308650ddb9ae@gmail.com>
Date:   Wed, 31 Jan 2018 19:14:34 +0100
From:   Philipp Rossak <embed3d@...il.com>
To:     Quentin Schulz <quentin.schulz@...e-electrons.com>
Cc:     lee.jones@...aro.org, robh+dt@...nel.org, mark.rutland@....com,
        maxime.ripard@...e-electrons.com, wens@...e.org,
        linux@...linux.org.uk, jic23@...nel.org, knaack.h@....de,
        lars@...afoo.de, pmeerw@...erw.net, davem@...emloft.net,
        hans.verkuil@...co.com, mchehab@...nel.org, rask@...melder.dk,
        clabbe.montjoie@...il.com, sean@...s.org, krzk@...nel.org,
        icenowy@...c.io, edu.molinas@...il.com, singhalsimran0@...il.com,
        linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-sunxi@...glegroups.com
Subject: Re: [PATCH v2 01/16] dt-bindings: update the Allwinner GPADC device
 tree binding for H3 & A83T



On 31.01.2018 18:40, Quentin Schulz wrote:
> Hi Philipp,
> 
> On Mon, Jan 29, 2018 at 12:29:04AM +0100, Philipp Rossak wrote:
>> Allwinner H3 features a thermal sensor like the one in A33, but has its
>> register re-arranged, the clock divider moved to CCU (originally the
>> clock divider is in ADC) and added a pair of bus clock and reset.
>>
>> Allwinner A83T features a thermal sensor similar to the H3, the ths clock,
>> the bus clock and the reset was removed from the CCU. The THS in A83T
>> has a clock that is directly connected and runs with 24 MHz.
>>
>> Update the binding document to cover H3 and A83T.
>>
>> Signed-off-by: Philipp Rossak <embed3d@...il.com>
>> ---
>>   .../devicetree/bindings/mfd/sun4i-gpadc.txt        | 50 ++++++++++++++++++++--
>>   1 file changed, 47 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/mfd/sun4i-gpadc.txt b/Documentation/devicetree/bindings/mfd/sun4i-gpadc.txt
>> index 86dd8191b04c..22df0c5c23d4 100644
>> --- a/Documentation/devicetree/bindings/mfd/sun4i-gpadc.txt
>> +++ b/Documentation/devicetree/bindings/mfd/sun4i-gpadc.txt
>> @@ -4,12 +4,35 @@ The Allwinner SoCs all have an ADC that can also act as a thermal sensor
>>   and sometimes as a touchscreen controller.
>>   
>>   Required properties:
>> -  - compatible: "allwinner,sun8i-a33-ths",
>> +  - compatible: must contain one of the following compatibles:
>> +		- "allwinner,sun8i-a33-ths"
>> +		- "allwinner,sun8i-h3-ths"
>> +		- "allwinner,sun8i-a83t-ths"
>>     - reg: mmio address range of the chip,
>> -  - #thermal-sensor-cells: shall be 0,
>> +  - #thermal-sensor-cells: shall be 0 or 1,
> 
> Well, thermal-sensor-cells is either 0 or 1 :)
> 
> Better to point to the documentation describing this
> thermal-sensor-cells IMHO.
> 

I agree, I will change this in the next version.

>>     - #io-channel-cells: shall be 0,
>>   
>> -Example:
>> +Required properties for the following compatibles:
>> +		- "allwinner,sun8i-h3-ths"
>> +		- "allwinner,sun8i-a83t-ths"
>> +  - interrupts: the sampling interrupt of the ADC,
>> +
>> +Required properties for the following compatibles:
>> +		- "allwinner,sun8i-h3-ths"
>> +  - clocks: the bus clock and the input clock of the ADC,
>> +  - clock-names: should be "bus" and "mod",
>> +  - resets: the bus reset of the ADC,
>> +
>> +Optional properties for the following compatibles:
>> +		- "allwinner,sun8i-h3-ths"
>> +  - nvmem-cells: A phandle to the calibration data provided by a nvmem device.
>> +		If unspecified default values shall be used. The size should
>> +		be 0x2 * sensorcount.
> 
> "twice the number of sensors" ?
> 

As already mentioned in an other answers, this here is not correct.
I got somehow a wrong information or mixed something up. For H5, H3, 
A83T and A64 the thermal sensor calibration data is always 64 bit wide 
and placed on the eFuse address  0x34 [1].

>> +  - nvmem-cell-names: Should be "calibration".
>> +
>> +Details see: bindings/nvmem/nvmem.txt
>> +
>> +Example for A33:
>>   	ths: ths@...5000 {
>>   		compatible = "allwinner,sun8i-a33-ths";
>>   		reg = <0x01c25000 0x100>;
>> @@ -17,6 +40,27 @@ Example:
>>   		#io-channel-cells = <0>;
>>   	};
>>   
>> +Example for H3:
>> +	ths: thermal-sensor@...5000 {
>> +		compatible = "allwinner,sun8i-h3-ths";
>> +		reg = <0x01c25000 0x400>;
>> +		clocks = <&ccu CLK_BUS_THS>, <&ccu CLK_THS>;
>> +		clock-names = "bus", "mod";
>> +		resets = <&ccu RST_BUS_THS>;
>> +		interrupts = <GIC_SPI 31 IRQ_TYPE_LEVEL_HIGH>;
>> +		#thermal-sensor-cells = <0>;
>> +		#io-channel-cells = <0>;
>> +	};
>> +
>> +Example for A83T:
>> +	ths: thermal-sensor@...4000 {
>> +		compatible = "allwinner,sun8i-a83t-ths";
>> +		reg = <0x01f04000 0x100>;
>> +		interrupts = <GIC_SPI 41 IRQ_TYPE_LEVEL_HIGH>;
>> +		#thermal-sensor-cells = <1>;
>> +		#io-channel-cells = <0>;
>> +	};
>> +
> 
> Aside from Maxime's comment on how we would like to refactor GPADC/THS,
> I'm not sure we really want an example for each an every thermal sensor
> supported.
> 
> Quentin
> 
I agree we don't want to have an example for every sensor, but I think 
at least those two are interesting, since one has 3 sensors and no 
clocks, and one has 1 sensor and clocks.

Thanks,
Philipp

[1]: http://linux-sunxi.org/SID_Register_Guide#eFUSE