libpayload: Add a timer_us() function.

This function returns the number of microseconds scaled from the number of raw
timer ticks. It accepts a base parameter which is subtracted from the current
time, which makes it easy to keep track of relative times.

Change-Id: I55f2f9e90c0e12cda430bbe88b044f12b0b563c8
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://chromium-review.googlesource.com/179600
Reviewed-by: Ronald Minnich <rminnich@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>
(cherry picked from commit 4dd549e18d170dbf918c5b4b11bbe1f4e99b6695)
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6897
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
2 files changed