[PATCH 4/4] ARM64: dts: meson: meson-gx: add the SAR ADC

[Heiner Kallweit]

Am 13.01.2017 um 20:50 schrieb Martin Blumenstingl:
> Hi Heiner,
> 
> On Fri, Jan 13, 2017 at 8:32 PM, Heiner Kallweit <hkallweit1 at gmail.com> wrote:
>> Sorry, I'm not subscribed to the two mailing lists, therefore my reply
>> is outside the thread.
>>
>> I'm currently experimenting with an own rudimentary driver for SAR ADC
>> on a Odroid C2 (S905GXBB). So I have some remarks based on my experience.
> I hope that we haven't been duplicating too much work!
> 
No, my driver doesn't include all the clock handling and relies on the
boot loader / firmware to do this. Also I don't support averaging mode.
Your driver is much more comprehensive and I would go with it.

I have some features like interrupt mode and calibration which are not
yet supported in your driver but they can be easily migrated and added
later.

Rgds, Heiner

>> Rgds, Heiner
>>
>>> Add the SAR ADC to meson-gxbb.dtsi and meson-gxl.dtsi. GXBB provides a
>>> 10-bit ADC while GXL (and GXM, which uses the same ADC as GXL) provides
>>> a 12-bit ADC.
>>> Some boards use resistor ladder buttons connected through one of the ADC
>>> channels. On newer devices (GXL and GXM) some boards use pull-ups/downs
>>> to change the resistance (and thus the ADC value) on of the ADC channels
>>> to indicate the board revision.
>>>
>>> Signed-off-by: Martin Blumenstingl <martin.blumenstingl at xxxxxxxxxxxxxx>
>>> ---
>>>  arch/arm64/boot/dts/amlogic/meson-gx.dtsi   |  8 ++++++++
>>>  arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi | 10 ++++++++++
>>>  arch/arm64/boot/dts/amlogic/meson-gxl.dtsi  | 10 ++++++++++
>>>  3 files changed, 28 insertions(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/amlogic/meson-gx.dtsi b/arch/arm64/boot/dts/amlogic/meson-gx.dtsi
>>> index cddad8c795ec..ed3bf29eb76a 100644
>>> --- a/arch/arm64/boot/dts/amlogic/meson-gx.dtsi
>>> +++ b/arch/arm64/boot/dts/amlogic/meson-gx.dtsi
>>> @@ -237,6 +237,14 @@
>>>                               status = "disabled";
>>>                       };
>>>
>>> +                     saradc: adc at 8680 {
>>> +                             compatible = "amlogic,meson-saradc";
>>> +                             #io-channel-cells = <1>;
>>> +                             status = "disabled";
>>> +                             reg = <0x0 0x8680 0x0 0x34>;
>>> +                             interrupts = <GIC_SPI 9 IRQ_TYPE_EDGE_RISING>;
>> IRQ 9 dosn't work for me, where does this number come from?
>> With IRQ 73 interrupt mode is working fine here.
>> Of course I can't speak for all other Meson variants.
> I think I took the IRQ from the vendor's mesongxbb.dtsi, depending on
> whether I'll add IRQ support or not I'll remove or fix this. Thanks
> for spotting this!
> 
> 
> Regards,
> Martin
>