linux-kernel - Re: [PATCH v2] hwmon: (sun4i-lradc) Add driver for LRADC found on Allwinner A13/A20 SoC

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Message-ID: <21a89ae0-7152-49eb-7500-7d46dfb259f6@roeck-us.net>
Date:   Mon, 2 May 2022 06:31:56 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Maxime Ripard <maxime@...no.tech>, Ruslan Zalata <rz@...micro.ru>
Cc:     Jean Delvare <jdelvare@...e.com>, Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Samuel Holland <samuel@...lland.org>,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev
Subject: Re: [PATCH v2] hwmon: (sun4i-lradc) Add driver for LRADC found on
 Allwinner A13/A20 SoC

On 5/2/22 04:00, Maxime Ripard wrote:
> Hi,
> 
> On Thu, Apr 28, 2022 at 09:09:03PM +0000, Ruslan Zalata wrote:
>> Some Allwinner SoCs like A13, A20 or T2 are equipped with two-channel
>> low rate (6 bit) ADC that is often used for extra keys. There's a driver
>> for that already implementing standard input device, but it has these
>> limitations: 1) it cannot be used for general ADC data equisition, and
>> 2) it uses only one LRADC channel of two available.
>>
>> This driver provides basic hwmon interface to both channels of LRADC on
>> such Allwinner SoCs.
>>
>> Signed-off-by: Ruslan Zalata <rz@...micro.ru>
>> ---
>>   MAINTAINERS                       |   6 +
>>   drivers/hwmon/Kconfig             |  13 ++
>>   drivers/hwmon/Makefile            |   1 +
>>   drivers/hwmon/sun4i-lradc-hwmon.c | 280 ++++++++++++++++++++++++++++++
>>   4 files changed, 300 insertions(+)
>>   create mode 100644 drivers/hwmon/sun4i-lradc-hwmon.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 5e8c2f61176..d9c71e94133 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -18861,6 +18861,12 @@ S:	Maintained
>>   F:	Documentation/devicetree/bindings/input/allwinner,sun4i-a10-lradc-keys.yaml
>>   F:	drivers/input/keyboard/sun4i-lradc-keys.c
>>   
>> +SUN4I LOW RES ADC HWMON DRIVER
>> +M:	Ruslan Zalata <rz@...micro.ru>
>> +L:	linux-hwmon@...r.kernel.org
>> +S:	Maintained
>> +F:	drivers/hwmon/sun4i-lradc-hwmon.c
>> +
>>   SUNDANCE NETWORK DRIVER
>>   M:	Denis Kirjanov <kda@...ux-powerpc.org>
>>   L:	netdev@...r.kernel.org
>> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
>> index 68a8a27ab3b..86776488a81 100644
>> --- a/drivers/hwmon/Kconfig
>> +++ b/drivers/hwmon/Kconfig
>> @@ -1691,6 +1691,19 @@ config SENSORS_SIS5595
>>   	  This driver can also be built as a module. If so, the module
>>   	  will be called sis5595.
>>   
>> +config SENSORS_SUN4I_LRADC
>> +	tristate "Allwinner A13/A20 LRADC hwmon"
>> +	depends on ARCH_SUNXI && !KEYBOARD_SUN4I_LRADC
>> +	help
>> +	  Say y here to support the LRADC found in Allwinner A13/A20 SoCs.
>> +	  Both channels are supported.
>> +
>> +	  This driver can also be built as module. If so, the module
>> +	  will be called sun4i-lradc-hwmon.
>> +
>> +	  This option is not compatible with KEYBOARD_SUN4I_LRADC, one
>> +	  of these must be used at a time.
> 
> How do you plan on enforcing that?
> 
	depends on ARCH_SUNXI && !KEYBOARD_SUN4I_LRADC
                                  ^^^^^^^^^^^^^^^^^^^^^

> I guess a better path forward would be to either register an hwmon
> device in the original driver, or convert that driver to iio and use
> iio-hwmon.
> 
Both is fine with me.

Guenter