ps2: Unify constant names

Move ps2.hh to dev/ps2/types.hh and update the device models to
consistently use well-known constants from this header.

Change-Id: Iadfdc774495957beb82f3d341107b1e9232ffd4c
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/9770
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

ps2: Add proper touchscreen command handling

The touchscreen model used ad-hoc mechanisms to enable/disable the
device. Use standard PS/2 commands to activate/deactivate the
device. Add proper TouchKit command handling.

Change-Id: I0c5a2e2b47639f36ab3ee07e3e559f11afa54b9d
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/9768
Reviewed-by: Gabe Black <gabeblack@google.com>

ps2: Unify device data buffering

All PS/2 device currently implement various ad-hoc mechanisms to
handle multi-byte commands. This is error-prone and makes it hard to
implement new devices. Create a buffering mechanism in the base class
to avoid this.

Change-Id: If5638b0ab68decea8de7631ecead0a9ebad1547b
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/9765
Reviewed-by: Gabe Black <gabeblack@google.com>

ps2: Add a simple touchscreen model

Add a touchscreen model that is compatible with Linux's TouchKit
driver. This model is based on the model in the Arm PL050 KMI model.

Change-Id: Id4d88a21a26bb42c455e4d778cd89875f650ac57
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/9764
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>