ps2-gpio: use ktime for IRQ timekeeping

[Danilo Krummrich <danilokrummrich@dk-develop.de>]

Changes since v1
================
  - add patch to refactor struct ps2_gpio_data for clear separation between
    RX and TX
  - make all variables for IRQ timekeeping per-port and initialize them in
    ps2_gpio_open()

This patch series implements the usage of ktime for IRQ timekeeping to
overcome:

(1) The resolution limitations of jiffies.
(2) Potential spurious IRQs generated by gpio controllers.

Besides that, based on the newly implemented timekeeping, it fixes a wrongly
suspected extra clock cycle for TX transfers and a race condition when
starting an immediate TX transfer based on data received from an RX transfer.

Danilo Krummrich (4):
      input: ps2-gpio: refactor struct ps2_gpio_data
      input: ps2-gpio: use ktime for IRQ timekeeping
      input: ps2-gpio: remove tx timeout from ps2_gpio_irq_tx()
      input: ps2-gpio: don't send rx data before the stop bit

 drivers/input/serio/ps2-gpio.c | 180 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------------------------------------------
 1 file changed, 116 insertions(+), 64 deletions(-)