drivers: clocksource: add support for ARM architected timer event stream

The ARM architected timer can generate events (used for waking up
CPUs executing the wfe instruction) at a frequency represented as a
power-of-2 divisor of the clock rate.

An event stream might be used:
- To implement wfe-based timeouts for userspace locking implementations.
- To impose a timeout on a wfe for safeguarding against any programming
  error in case an expected event is not generated.

This patch computes the event stream frequency aiming for a period
of 100us between events. It uses ARM/ARM64 specific backends to configure
and enable the event stream.

Cc: Lorenzo Pieralisi <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
Acked-by: Olof Johansson <[email protected]>
Signed-off-by: Will Deacon <[email protected]>
[sudeep: moving ARM/ARM64 changes into separate patches
         and adding Kconfig option]
Signed-off-by: Sudeep KarkadaNagesha <[email protected]>

0 files changed, 0 insertions, 0 deletions