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SubjectRe: [PATCH v2 00/10] Add support for SAMA5D2 touchscreen
On Tue, 27 Mar 2018 15:32:33 +0300
Eugen Hristev <> wrote:

> Hello,
> This patch series is a rework of my previous series named:
> [PATCH 00/14] iio: triggers: add consumer support
> In few words, this is the implementation of splitting the functionality
> of the IP block ADC device in SAMA5D2 SoC from ADC with touchscreen
> support. In order to avoid having a MFD device, two separate
> drivers that would work on same register base and split the IRQ,etc,
> as advised on the mailing list, I created a consumer driver for the
> channels, that will connect to the ADC as described in the device tree.
> I have collected feedback from everyone and here is the result:
> I have added a new generic resistive touchscreen driver, which acts
> as a iio consumer for the given channels and will create an input
> device and report the events. It uses a callback buffer to register
> to the IIO device and waits for data to be pushed.
> Inside the IIO device, I have kept a similar approach with the first version
> of the series, except that now the driver can take multiple buffers, and
> will configure the touchscreen part of the hardware device if the specific
> channels are requested.
> The SAMA5D2 ADC driver registers three new channels: two for the
> position on the X and Y axis, and one for the touch pressure.
> When channels are requested, it will check if the touchscreen channel mask
> includes the requested channels (it is possible that the consumer driver
> will not request pressure for example). If it's the case, it will work
> in touchscreen mode, and will refuse to do usual analog-digital conversion,
> because we have a single trigger and the touchscreen needs it.
> When the scan mask will include only old channels, the driver will function
> in the same way as before. If the scan mask somehow is a mix of the two (the
> masks intersect), the driver will refuse to work whatsoever (cannot have both
> in the same time).
> The driver allows reading raw data for the new channels, if claim direct
> mode works: no touchscreen driver requested anything. The new channels can
> act like the old ones. However, when requesting these channels, the usual
> trigger will not work and will not be enabled. The touchscreen channels
> require special trigger and irq configuration: pen detect, no pen detect
> and a periodic trigger to sample the touchscreen position and pressure.
> If the user attempts to use another trigger while there is a buffer
> that already requested the touchscreen channels (thus the trigger), the
> driver will refuse to comply.
> In order to have defines for the channel numbers, I added a bindings include
> file that goes on a separate commit :
> dt-bindings: iio: adc: at91-sama5d2_adc: add channel specific consumer info
> This should go in the same tree with the following commits :
> ARM: dts: at91: sama5d2: add channel cells for ADC device
> ARM: dts: at91: sama5d2: Add resistive touch device
> as build will break because these commits depend on the binding one
> which creates the included header file.
> After the discussions earlier this year on the mailing list, I hope this
> rework of the patches is much better and fulfills all the requirements
> for this implementation.
As I said in one of the later patches, I like this a lot.
It is a good blend of the moderately nasty handling needed in the ADC
driver with a lovely generic input driver.

Very nice! Hope everyone else agrees ;)


> Eugen Hristev (10):
> MAINTAINERS: add generic resistive touchscreen adc
> iio: Add channel for Position Relative
> dt-bindings: input: touchscreen: touch_adc: create bindings
> iio: inkern: add module put/get on iio dev module when requesting
> channels
> iio: adc: at91-sama5d2_adc: fix channel configuration for differential
> channels
> iio: adc: at91-sama5d2_adc: add support for position and pressure
> channels
> input: touchscreen: touch_adc: add generic resistive ADC touchscreen
> dt-bindings: iio: adc: at91-sama5d2_adc: add channel specific consumer
> info
> ARM: dts: at91: sama5d2: add channel cells for ADC device
> ARM: dts: at91: sama5d2: Add resistive touch device
> Documentation/ABI/testing/sysfs-bus-iio | 12 +
> .../bindings/iio/adc/at91-sama5d2_adc.txt | 9 +
> .../bindings/input/touchscreen/touch_adc.txt | 33 ++
> arch/arm/boot/dts/sama5d2.dtsi | 12 +
> drivers/iio/adc/at91-sama5d2_adc.c | 491 ++++++++++++++++++++-
> drivers/iio/industrialio-core.c | 1 +
> drivers/iio/inkern.c | 8 +-
> drivers/input/touchscreen/Kconfig | 13 +
> drivers/input/touchscreen/Makefile | 1 +
> drivers/input/touchscreen/touch_adc.c | 199 +++++++++
> include/dt-bindings/iio/adc/at91-sama5d2_adc.h | 16 +
> include/uapi/linux/iio/types.h | 1 +
> tools/iio/iio_event_monitor.c | 2 +
> 14 files changed, 791 insertions(+), 13 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/input/touchscreen/touch_adc.txt
> create mode 100644 drivers/input/touchscreen/touch_adc.c
> create mode 100644 include/dt-bindings/iio/adc/at91-sama5d2_adc.h

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