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Author: David Lechner
To: Sicelo
CC: linux-iio, maemo-leste, Ivaylo Dimitrov, linux-input
Subject: Re: [maemo-leste] supporting binary (near-far) proximity sensors over gpio
On Fri, Nov 17, 2023 at 12:22 PM Sicelo <absicsz@???> wrote:
> Hi
> Some phones have 1-bit proximity sensors, which simply toggle a GPIO
> line to indicate that an object is near or far. Thresholds are set at
> hardware level. One such sensor is OSRAM SFH 7741 [1], which is used on
> the Nokia N900.
> It is currently exported over evdev, emitting the SW_FRONT_PROXIMITY key
> code [2].
> So the question is: should a new, general purpose iio-gpio driver be
> written, that would switch such a proximity sensor to the iio framework?
> Or evdev is really the best place to support it?
> There are a couple of people who are willing to write such an iio
> driver, if iio is the way to go.
> Regards,
> Sicelo
> [1] https://media.digikey.com/pdf/Data%20Sheets/Osram%20PDFs/SFH_7741.pdf
> [2] https://elixir.bootlin.com/linux/v6.6.1/source/arch/arm/boot/dts/ti/omap/omap3-n900.dts#L111

Since this is really a proximity switch (it is either on or off)
rather than measuring a proximity value over a continuous range, it
doesn't seem like a good fit for the iio subsystem. If the sensor is
on a phone, then it is likely to detect human presence so the input
subsystem does seem like the right one for that application.

More at https://www.kernel.org/doc/html/latest/driver-api/iio/intro.html