[PATCH 3/4] iio: mxs: Implement support for touchscreen

[Fabio Estevam]

On Fri, Dec 7, 2012 at 1:24 PM, Marek Vasut <marex at denx.de> wrote:
> This patch implements support for sampling of a touchscreen into
> the MXS LRADC driver. The LRADC block allows configuring some of
> it's channels into special mode where they either output the drive
> voltage or sample it, allowing it to operate a 4-wire or 5-wire
> resistive touchscreen.
>
> In case the touchscreen mode is enabled, the LRADC slot #7 is
> reserved for touchscreen only, therefore it is not possible to
> sample 8 LRADC channels at time, but only 7 channels.
>
> The touchscreen controller is configured such that the PENDOWN event
> disables touchscreen interrupts and triggers execution of worker
> thread, which then polls the touchscreen controller for X, Y and
> Pressure values. This reduces the overhead of interrupt-driven
> operation. Upon the PENUP event, the worker thread re-enables the
> PENDOWN detection interrupt and exits.
>
> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Fabio Estevam <fabio.estevam at freescale.com>
> Cc: Jonathan Cameron <jic23 at kernel.org>
> Cc: Shawn Guo <shawn.guo at linaro.org>
> ---
>  .../bindings/staging/iio/adc/mxs-lradc.txt         |    6 +
>  drivers/staging/iio/adc/mxs-lradc.c                |  435 +++++++++++++++++++-

What about adding the touchscreen support into a separate file, so
that users can select/deselect it via Kconfig option?

Not everyone using lradc would be necessarily interested in the
touchscreen functionality, so better to let it optional.

Thanks,

Fabio Estevam