[Letux-kernel] [RFC 0/4] iio-input-bridge so that accelerometers which only have an iio driver can still present evdev input events

H. Nikolaus Schaller hns at goldelico.com
Mon Mar 18 21:39:30 CET 2019


Some user spaces (e.g. some Android) use /dev/input/event* for handling the 3D
position of the device with respect to the center of gravity (earth). This can
be used for gaming input, rotation of screens etc.

This should be the standard because this interface is an abstraction of how
this data is acquired from sensor chips. Sensor chips may be connected through
different interfaces and in different positions. They may also have different
parameters. And, if a chip is replaced by a different one, the values reported
by the device position interface should remain the same.

But nowadays, new accelerometer chips usually just get iio drivers and rarely
an evdev input driver.

Therefore we need something like a protocol stack: input device vs. raw data.
It can be seen as a similar layering like TCP/IP vs. bare Ethernet. Or keyboard
input events vs. raw gpio or raw USB access.

This patch set bridges the gap between raw iio data and the input device abstraction
so that accelerometer measurements can also be presented as X/Y/Z accelerometer
channels (INPUT_PROP_ACCELEROMETER) through /dev/input/event*.


H. Nikolaus Schaller (4):
  iio: input-bridge: optionally bridge iio acceleometers to create a
    /dev/input
  iio: input-bridge: add iio-input-bridge to Makefile
  iio: input-bridge: add IIO_INPUT_BRIDGE kernel config option
  iio: input-bridge: make the iio-input-bridge driver called by iio-core

 drivers/iio/Kconfig                    |   7 +
 drivers/iio/Makefile                   |   1 +
 drivers/iio/industrialio-core.c        |  12 +
 drivers/iio/industrialio-inputbridge.c | 420 +++++++++++++++++++++++++
 drivers/iio/industrialio-inputbridge.h |  28 ++
 5 files changed, 468 insertions(+)
 create mode 100644 drivers/iio/industrialio-inputbridge.c
 create mode 100644 drivers/iio/industrialio-inputbridge.h

-- 
2.19.1



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