linux-kernel - Re: [PATCH 0/3] add support for Allwinner SoCs ADC

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Date:	Wed, 29 Jun 2016 11:28:03 +0800
From:	Chen-Yu Tsai <wens@...e.org>
To:	Quentin Schulz <quentin.schulz@...e-electrons.com>
Cc:	jdelvare@...e.com, Guenter Roeck <linux@...ck-us.net>,
	jic23@...nel.org, knaack.h@....de, lars@...afoo.de,
	pmeerw@...erw.net,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Chen-Yu Tsai <wens@...e.org>, Lee Jones <lee.jones@...aro.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-hwmon@...r.kernel.org, linux-iio@...r.kernel.org,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Antoine Ténart <antoine.tenart@...e-electrons.com>
Subject: Re: [PATCH 0/3] add support for Allwinner SoCs ADC

Hi,

On Tue, Jun 28, 2016 at 4:45 PM, Quentin Schulz
<quentin.schulz@...e-electrons.com> wrote:
> The Allwinner SoCs all have an ADC that can also act as a touchscreen controller
> and a thermal sensor. The first four channels can be used either for the ADC or
> the touchscreen and the fifth channel is used for the thermal sensor. We
> currently have a driver for the two latter functions in
> drivers/input/touchscreen/sun4i-ts.c but we don't have access to the ADC feature
> at all.
>
> This adds initial support for Allwinner SoCs ADC with all features. Yet, the
> touchscreen is not implemented but will be added later. To switch between
> touchscreen and ADC modes, you need to poke few bits in registers and
> (de)activate an interrupt (pen-up).
> A MFD is provided to let the input driver activate the pen-up interrupt through
> virtual interrupt, poke few bits via regmap and read data from the ADC driver
> while both (and iio_hwmon) are probed by the MFD.

I take it that we are going to replace the original sun4i-ts driver
with this new mfd one, and various sub device drivers?

> There exists slight modifications between the different SoCs ADC like the
> address of some registers and the scale and offset to apply to thermal sensor
> raw values. These modifications are done by drivers on different
> platform_device_id passed by the MFD when probing subdrivers.
>
> This also modifies iio-hwmon to allow probe deferring when no iio channel is
> found. Currently when no iio channel is found, the probing of iio-hwmon fails.
> This is problematic when iio-hwmon probes before the iio driver could register
> iio channels to share.

One thing about iio-hwmon is that it doesn't support hwmon labels.
Any chance you could improve this, so we see the same names in userspace?

Thanks
ChenYu

>
> Quentin Schulz (3):
>   mfd: add support for Allwinner SoCs ADC
>   iio: adc: add support for Allwinner SoCs ADC
>   hwmon: iio_hwmon: defer probe when no channel is found
>
>  drivers/hwmon/iio_hwmon.c           |   5 +-
>  drivers/iio/adc/Kconfig             |  12 ++
>  drivers/iio/adc/Makefile            |   1 +
>  drivers/iio/adc/sunxi-gpadc-iio.c   | 371 ++++++++++++++++++++++++++++++++++++
>  drivers/mfd/Kconfig                 |  14 ++
>  drivers/mfd/Makefile                |   2 +
>  drivers/mfd/sunxi-gpadc-mfd.c       | 188 ++++++++++++++++++
>  include/linux/mfd/sunxi-gpadc-mfd.h |  14 ++
>  8 files changed, 606 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/iio/adc/sunxi-gpadc-iio.c
>  create mode 100644 drivers/mfd/sunxi-gpadc-mfd.c
>  create mode 100644 include/linux/mfd/sunxi-gpadc-mfd.h
>
> --
> 2.5.0
>