synaptics_detect() does not check whether sending commands to the
device succeeds and instead relies on getting unique data from the
device. Let's make sure we seed entire buffer with zeroes to make sure
we will not use garbage on stack that just happen to be 0x47.

Reported-by: syzbot+13cb3b01d0784e4ffc3f@syzkaller.appspotmail.com
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Bring in xen-kbdfront changes.

This seems to be Synaptics specific, as some Elan touchpads are not
correctly switching to SMBus if we call deactivate before switching to
SMBus on cold boot and on resume.

Tested with the T480s

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: KT Liao <kt.liao@emc.com.tw>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

This time, Lenovo decided to go with different pieces in its latest
series of Thinkpads.

For those we have been able to test:
- the T480 is using Synaptics with an IBM trackpoint
   -> it behaves properly with or without intertouch, there is no point
      not using RMI4
- the X1 Carbon 6th gen is using Synaptics with an IBM trackpoint
   -> the touchpad doesn't behave properly under PS/2 so we have to
      switch it to RMI4 if we do not want to have disappointed users
- the X280 is using Synaptics with an ALPS trackpoint
   -> the recent fixes in the trackpoint handling fixed it so upstream
      now works fine with or without RMI4, and there is no point not
      using RMI4
- the T480s is using an Elan touchpad, so that's a different story

Cc: <stable@vger.kernel.org> # v4.14.x, v4.15.x, v4.16.x
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: KT Liao <kt.liao@emc.com.tw>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Synaptics devices reported it has Intertouch support,
and it fails via PS/2 as following logs:

psmouse serio2: Failed to reset mouse on synaptics-pt/serio0
psmouse serio2: Failed to enable mouse on synaptics-pt/serio0

Set these new devices to use SMBus to fix this issue, then they report
SMBus version 3 is using, patch:
https://patchwork.kernel.org/patch/9989547/ enabled SMBus ver 3 and
makes synaptics devices work fine on SMBus mode.

Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Lenovo use two different trackpoints in the fifth generation Thinkpad X1
Carbon. Both are accessible over SMBUS/RMI but the pnpIDs are missing.
This patch is for the Elantech trackpoint specifically which also
reports SMB version 3 so rmi_smbus needs to be updated in order to
handle it.

For the record, I was not the first one to come up with this patch as it
has been floating around the internet for a while now. However, I have
spent significant time with testing and my efforts to find the original
author of the patch have been unsuccessful.

Signed-off-by: Edvard Holst <edvard.holst@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

The touchpad on Lenovo Carbon X1 Gen 5 (2017 - Kabylake) is accessible over
SMBUS/RMI, so let's activate it by default.

Cc: stable@vger.kernel.org
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Sync up with chrome-platform to bring in changes to Atmel touch
controller.

Prepare input updates for 4.17 merge window.

Merge various PS/2 handling improvements.