pistachio: implement timer support

C0_COUNT register is a free running counter clocked by the CPU
frequency divided by two. On the FPGA board it results in 25 MHz, on
real SOCs it will have to be figured out later.

Some magic addresses and numbers are used to find out if the code is
running on the FPGA board.

timestamp_get() and timer_monotonic_get() are kept in the same file.

The CPU initialization makes sure that CO COUNT is in fact enabled and
starts from zero.

TEST=with timer enabled, the startup code properly initializes UART
     and prints the coreboot bootblock banner message on the serial

Change-Id: I98fe330b961f677448b222917ab7d586494ed4b7
Signed-off-by: Stefan Reinauer <reinauer@chromium.org>
Original-Commit-Id: a7324221c1d856ac72fa2b0ab586b5ea8cab3a05
Original-Change-Id: I2d518213de939e91a35f8aea174aed76d297dd72
Original-Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/227888
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/9188
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
5 files changed