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author | Artur Rojek <contact@artur-rojek.eu> | 2020-07-19 23:53:07 +0300 |
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committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2020-07-20 12:28:39 +0300 |
commit | b96952f498db61cdce60f3161a445442d1cc08bc (patch) | |
tree | 80843dab2b0a2463c1bbd8320e38209f285ed323 /include/dt-bindings | |
parent | 842247203c33151c5a8007f9a0bec7ba378705d2 (diff) | |
download | linux-b96952f498db61cdce60f3161a445442d1cc08bc.tar.xz |
IIO: Ingenic JZ47xx: Add touchscreen mode.
The SADC component in JZ47xx SoCs provides support for touchscreen
operations (pen position and pen down pressure) in single-ended and
differential modes.
The touchscreen component of SADC takes a significant time to stabilize
after first receiving the clock and a delay of 50ms has been empirically
proven to be a safe value before data sampling can begin.
Of the known hardware to use this controller, GCW Zero and Anbernic RG-350
utilize the touchscreen mode by having their joystick(s) attached to the
X/Y positive/negative input pins.
JZ4770 and later SoCs introduce a low-level command feature. With it, up
to 32 commands can be programmed, each one corresponding to a sampling
job. It allows to change the low-voltage reference, the high-voltage
reference, have them connected to VCC, GND, or one of the X-/X+ or Y-/Y+
pins.
This patch introduces support for 6 stream-capable channels:
- channel #0 samples X+/GND
- channel #1 samples Y+/GND
- channel #2 samples X-/GND
- channel #3 samples Y-/GND
- channel #4 samples X+/X-
- channel #5 samples Y+/Y-
Being able to sample X-/GND and Y-/GND is useful on some devices, where
one joystick is connected to the X+/Y+ pins, and a second joystick is
connected to the X-/Y- pins.
All the boards which probe this driver have the interrupt provided from
Device Tree, with no need to handle a case where the IRQ was not provided.
Co-developed-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Diffstat (limited to 'include/dt-bindings')
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