Re: [RFC/PATCH 0/6] iio: Add sensorhub driver

From: Karol Wrona
Date: Mon Sep 08 2014 - 10:55:30 EST

On 09/03/2014 09:52 PM, Jonathan Cameron wrote:

On September 3, 2014 3:55:44 PM GMT+01:00, Karol Wrona <k.wrona@xxxxxxxxxxx> wrote:
Hello,

This patchset adds support for sensorhub. It is an external mcu which
manages
and collects data from several sensors i.e. on Galaxy Gear 2 watch.

It contains:
- spi driver for sensorhub device
- DT binding for the device
- IIO common utils for ssp sensors, a trigger module
- IIO accelerometer driver
- IIO gyroscope driver

Generally this is an attempt to generalize sensors handling on some
Samsung
boards which have multiple sensors IC and also sensorhub does some data
processing itself.

I would like to get your opinion about such solution. The idea is that
data communication layer gives control and data to proper IIO sensor
devices.
In this case I chose that sensor drivers are platform ones represented
by
child nodes of sensorhub in DT. These compatibles are used mainly to
match
sensor to driver. For example at this stage there is one accelerometer
but on
other board can have different one with changed data format etc. In
this case
ssp_accel_sensor driver could handle several physical devices of accel
class.
Unfortunately the firmware gives only an information about used sensor
type,
the driver can find out that there is an accelerometer on board but
nothing
specific about the sensor.
Will look at this later... In the meantime..
Before code review I want to know your opinion if passing information
about sensors in that way is ok - It's a hack but currently the firmware
do not provide such information and I do not know if I will be able to
change it.
Other question:
The sensorhub can implement some devices which are non common for IIO
and hard
to standardise. These ones need two way communication (raw write will
not be
proper for that) and can produce data packets with flexible size to
2KB).
I'm wondering if it is worth to look for solution in IIO and implement
something like IIO_BULK sensor with no standard channel description
or solve this problem using cdev. This is the reason why the part of
the
patchset is intended to be placed in misc.
Out of curiosity, what are these other sensors, roughly? If they are popular I am
sure there will be more out there soon! Ideally we would work out how to standardize these. So convince is it can't be
done!
These are very specific for Galaxy Gear watch like movement detector, pedometer,
put down motion etc. The functionalities are mainly implemented by sensorhub
firmware, these ones are not physical chips. My first idea was to use IIO for typical
sensors only (I can have there a bunch of thermometers, accelerometers, lightsensors ...)
and one cdev for others. In this case data interpretation would be done by userspace.
So:
- these specific "sensors" will be only implemented on some Samsung's boards
and depend on firmware.
- there will be a lot of it - most of them are represented by an integer value but there
are some which can send much more data.

Regards,
Karol

Karol Wrona (6):
iio:sensorhub: Add sensorhub common library
misc: sensorhub: Add sensorhub driver
sensorhub: Add sensorhub bindings
iio: sensorhub: Add sensorhub iio commons
iio: sensorhub: Add sensorhub accelerometer sensor
iio: sensorhub: Add sensorhub gyroscope sensor

.../devicetree/bindings/misc/sensorhub.txt | 51 ++
drivers/iio/accel/Makefile | 2 +
drivers/iio/accel/ssp_accel_sensor.c | 240 ++++++
drivers/iio/common/Kconfig | 1 +
drivers/iio/common/Makefile | 1 +
drivers/iio/common/ssp_sensors/Kconfig | 15 +
drivers/iio/common/ssp_sensors/Makefile | 6 +
.../iio/common/ssp_sensors/ssp-sensor-trigger.c | 92 +++
drivers/iio/common/ssp_sensors/ssp_iio.c | 35 +
drivers/iio/common/ssp_sensors/ssp_iio_sensor.h | 62 ++
drivers/iio/gyro/Makefile | 2 +
drivers/iio/gyro/ssp_gyro_sensor.c | 225 ++++++
drivers/misc/Kconfig | 1 +
drivers/misc/Makefile | 1 +
drivers/misc/sensorhub/Kconfig | 13 +
drivers/misc/sensorhub/Makefile | 8 +
drivers/misc/sensorhub/ssp.h | 323 ++++++++
drivers/misc/sensorhub/ssp_data.c | 61 ++
drivers/misc/sensorhub/ssp_dev.c | 782
++++++++++++++++++++
drivers/misc/sensorhub/ssp_firmware.c | 571
++++++++++++++
drivers/misc/sensorhub/ssp_spi.c | 700
++++++++++++++++++
include/linux/iio/common/ssp_sensors.h | 82 ++
22 files changed, 3274 insertions(+)
create mode 100644 Documentation/devicetree/bindings/misc/sensorhub.txt
create mode 100644 drivers/iio/accel/ssp_accel_sensor.c
create mode 100644 drivers/iio/common/ssp_sensors/Kconfig
create mode 100644 drivers/iio/common/ssp_sensors/Makefile
create mode 100644 drivers/iio/common/ssp_sensors/ssp-sensor-trigger.c
create mode 100644 drivers/iio/common/ssp_sensors/ssp_iio.c
create mode 100644 drivers/iio/common/ssp_sensors/ssp_iio_sensor.h
create mode 100644 drivers/iio/gyro/ssp_gyro_sensor.c
create mode 100644 drivers/misc/sensorhub/Kconfig
create mode 100644 drivers/misc/sensorhub/Makefile
create mode 100644 drivers/misc/sensorhub/ssp.h
create mode 100644 drivers/misc/sensorhub/ssp_data.c
create mode 100644 drivers/misc/sensorhub/ssp_dev.c
create mode 100644 drivers/misc/sensorhub/ssp_firmware.c
create mode 100644 drivers/misc/sensorhub/ssp_spi.c
create mode 100644 include/linux/iio/common/ssp_sensors.h

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/