From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: Re: [PATCH 1/2] iio: sun4i-lradc: Add binding documentation Date: Sat, 2 Jul 2016 11:32:07 +0200 Message-ID: <777642fd-5e77-206f-a503-23bbf187e6f3@redhat.com> References: <1467406855-9677-1-git-send-email-alexandre.belloni@free-electrons.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Chen-Yu Tsai , Alexandre Belloni Cc: Jonathan Cameron , Maxime Ripard , linux-iio@vger.kernel.org, linux-arm-kernel , linux-kernel , Rob Herring , devicetree List-Id: devicetree@vger.kernel.org Hi, On 02-07-16 11:12, Chen-Yu Tsai wrote: > Hi, > > On Sat, Jul 2, 2016 at 5:00 AM, Alexandre Belloni > wrote: >> Document the bindings for the Allwinner LRADC. > > We already have Documentation/devicetree/bindings/input/sun4i-lradc-keys.txt > and I'm pretty sure Hans (CC-ed) argued that this is not a generic ADC > block. Right, this block is used on many tablets and some dev boards to provide buttons (as in the hid type) and the block is designed for this purpose, giving an irq when the adc level crosses a certain threshold. Sure it can be used in a more generic way, but that is not its primary goal. So any generic purpose adc driver must not break the current use-case (which is already used in mainline kernel dts files in plenty of cases). I believe that the best way to deal with this is to add an "allwinner,general-purpose-mode" flag to the existing binding (as well as document general purpose mode in the existing binding rather then in a new binding doc). That seems to be the right thing to do purely looking at this from a dt binding pov. For the implementation of this we can simpy have 2 drivers, then both drivers can check the flag and if present return -ENODEV from the existing input driver and likewise if not present return -ENODEV from the iio driver. We may actually use a similar solution for the touchscreen controller which can also be alternatively used as a generic purpose adc. Regards, Hans > Any plans to reconcile the different bindings? > > Thanks > ChenYu > >> >> Signed-off-by: Alexandre Belloni >> --- >> Cc: Rob Herring >> Cc: devicetree@vger.kernel.org >> >> .../devicetree/bindings/iio/adc/sun4i-lradc.txt | 19 +++++++++++++++++++ >> 1 file changed, 19 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/iio/adc/sun4i-lradc.txt >> >> diff --git a/Documentation/devicetree/bindings/iio/adc/sun4i-lradc.txt b/Documentation/devicetree/bindings/iio/adc/sun4i-lradc.txt >> new file mode 100644 >> index 000000000000..c75a6067b8a5 >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/iio/adc/sun4i-lradc.txt >> @@ -0,0 +1,19 @@ >> +Allwinner sun4i Low Resolution ADC >> +---------------------------------- >> + >> +Required properties: >> + - compatible: "allwinner,sun4i-a10-lradc" >> + - reg: mmio address range of the chip >> + - interrupts: interrupt to which the chip is connected >> + - vref-supply: powersupply for the lradc reference voltage >> + - #io-channel-cells = <1>; As ADC has multiple outputs >> + >> +Example: >> + >> + lradc: lradc@01c22800 { >> + compatible = "allwinner,sun4i-a10-lradc"; >> + reg = <0x01c22800 0x100>; >> + interrupts = <31>; >> + vref-supply = <®_vcc3v0>; >> + #io-channel-cells = <1>; >> + }; >> -- >> 2.8.1 >>