add acpi pmtimer support

This patch makes seabios use the acpi pmtimer instead of tsc for
timekeeping.  The pmtimer has a fixed frequency and doesn't need
calibration, thus it doesn't suffer from calibration errors due to a
loaded host machine.

[ v4: mask port ioport read ]
[ v2: add CONFIG_PMTIMER ]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/util.h b/src/util.h
index 062eea3..7723bb1 100644
--- a/src/util.h
+++ b/src/util.h
@@ -282,6 +282,7 @@ void lpt_setup(void);
 // clock.c
 #define PIT_TICK_RATE 1193180   // Underlying HZ of PIT
 #define PIT_TICK_INTERVAL 65536 // Default interval for 18.2Hz timer
+void pmtimer_init(u16 ioport, u32 khz);
 int check_tsc(u64 end);
 void timer_setup(void);
 void ndelay(u32 count);