Input: atmel_mxt_ts - verify Information Block checksum on probe

By reading the information block and the object table into a contiguous region
of memory, we can verify the checksum at probe time. This means we verify that
we are indeed talking to a chip that supports object protocol correctly. We
also detect I2C comms problems much earlier, resulting in easier diagnosis.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Input: atmel_mxt_ts - use T18 RETRIGEN to handle IRQF_TRIGGER_LOW

The workaround of reading all messages until an invalid is received is a way
of forcing the CHG line high, which means that when using edge-triggered
interrupts the interrupt can be acquired.

With level-triggered interrupts this is unnecessary.

Also, most recent maXTouch chips have a feature called RETRIGEN which, when
enabled, reasserts the interrupt line every cycle if there are messages
waiting. This also makes the workaround unnecessary.

Note: the RETRIGEN feature is only in some firmware versions/chips, it's not
valid simply to enable the bit.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Acked-by: Yufeng Shen <miletus@chromium.org>
Input: atmel_mxt_ts - handle reports from T47 Stylus object

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Acked-by: Yufeng Shen <miletus@chromium.org>
Input: atmel_mxt_ts - release touch state during suspend

If fingers are down as the MXT chip goes into suspend it does not send a lift
message. In addition, it may not complete its final measurement cycle
immediately, which means touch messages may be received by the interrupt
handler after mxt_stop() has completed.

So:
- disable irq during suspend
- flush any messages created after suspend
- tell app layer that slots were released at suspend

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Acked-by: Yufeng Shen <miletus@chromium.org>
Input: atmel_mxt_ts - initialize power config before and after downloading cfg

If the power configuration is zero then the configuration download may fail to
work properly, so initialize T7 before config download. The downloaded
configuration may reset the T7 power configuration so it must be
re-initialized afterwards.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Acked-by: Yufeng Shen <miletus@chromium.org>
Input: atmel_mxt_ts - add regulator control support

Allow the driver to optionally manage enabling/disable power to the touch
controller itself. If the regulators are not present then use the deep sleep
power mode instead.

For a correct power on sequence, it is required that we have control over the
RESET line.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Acked-by: Yufeng Shen <miletus@chromium.org>
Input: atmel_mxt_ts - implement support for T100 touch object

The T100 object replaces the old T9 multitouch touchscreen object in new
chips.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Yufeng Shen <miletus@chromium.org>
Input: atmel_mxt_ts - allow specification of firmware file name

On platforms which have multiple device instances using this driver, the
firmware may be different on each device. This patch makes the user give the
name of the firmware file when flashing.

This also prevents accidental triggering of the firmware load process.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Acked-by: Yufeng Shen <miletus@chromium.org>
Input: atmel_mxt_ts - set default irqflags when there is no pdata

This is the preparation for supporting the code path when there is
platform data provided and still boot the device into a sane state
with backup NVRAM config.

Make the irqflags default to be IRQF_TRIGGER_FALLING if no platform data is
provided.

Signed-off-by: Yufeng Shen <miletus@chromium.org>
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Acked-by: Yufeng Shen <miletus@chromium.org>
Input: atmel_mxt_ts - handle cfg filename via pdata/sysfs

There may be multiple maXTouch chips on a single device which will require
different configuration files. Add a platform data value for the configuration
filename.

Add sysfs entry to write configuration file if the platform data is not set.

Split out the object initialisation code from mxt_initialize() into
mxt_configure_objects() to allow this.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Yufeng Shen <miletus@chromium.org>
Input: atmel_mxt_ts - only use first T9 instance

The driver only registers one input device, which uses the screen parameters
from the first T9 instance. The first T63 instance also uses those parameters.

It is incorrect to send input reports from the second instances of these
objects if they are enabled: the input scaling will be wrong and the positions
will be mashed together.

This also causes problems on Android if the number of slots exceeds 32.

In the future, this could be handled by looking for enabled touch object
instances and creating an input device for each one.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Acked-by: Yufeng Shen <miletus@chromium.org>
Input: atmel_mxt_ts - allow input name to be specified in platform data

Android systems identify the input device and map to IDC file by using the
input device name. To avoid unnecessary deltas to the driver file, allow this
to be set from the platform data.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Input: atmel_mxt_ts - implement I2C retries

Some maXTouch chips (eg mXT1386) will not respond on the first I2C request
when they are in a sleep state. It must be retried after a delay for the chip
to wake up.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Yufeng Shen <miletus@chromium.org>
Input: atmel_mxt_ts - implement debug output for messages

Add a debug switch which causes all messages from the touch controller to be
dumped to the dmesg log with a set prefix "MXT MSG:". This is used by Atmel
user-space utilities to debug touch operation. Enabling this output does
impact touch performance.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Input: atmel_mxt_ts - add memory access interface via sysfs

Atmel maXTouch chips can be addressed via an "Object Based Protocol" which
defines how i2c registers are mapped to different functions within the
chips. This interface exposes the register map and allows user-space
utilities to inspect and alter object configuration, and to view diagnostic
data, while the device is running.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Input: atmel_mxt_ts - implement improved debug message interface

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Input: atmel_mxt_ts - initialise input slots with INPUT_MT_DIRECT

This indicates the device coordinates should be directly mapped to screen.
This is valid since scaling/flipping/rotation should be done by configuring
the MXT device.

It also flags to Android using INPUT_PROP_DIRECT that the device should be
treated as a touch screen by default, and removes the necessity for a default
IDC file.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Input: atmel_mxt_ts - Improve device tree parsing for earlier kernels

The of_property_read_u32_index() function was only introduced in v3.10. Using
the array operation is simpler anyway.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Input: atmel_mxt_ts - Add device tree support for reset-gpio

Signed-off-by: Filipe Braz <filipe.braz@honeywell.com>
Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Input: atmel_mxt_ts - support config checksum attribute in sysfs

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>