diff options
Diffstat (limited to 'src/drivers/pc80/pc/i8254.c')
| -rw-r--r-- | src/drivers/pc80/pc/i8254.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/src/drivers/pc80/pc/i8254.c b/src/drivers/pc80/pc/i8254.c index 8e15d4ded1..654f84a6d7 100644 --- a/src/drivers/pc80/pc/i8254.c +++ b/src/drivers/pc80/pc/i8254.c @@ -11,6 +11,7 @@ * GNU General Public License for more details. */ +#include <arch/early_variables.h> #include <arch/io.h> #include <commonlib/helpers.h> #include <cpu/x86/tsc.h> @@ -122,3 +123,25 @@ unsigned long calibrate_tsc_with_pit(void) bad_ctc: return 0; } + +#if CONFIG(UNKNOWN_TSC_RATE) +static u32 g_timer_tsc CAR_GLOBAL; + +unsigned long tsc_freq_mhz(void) +{ + u32 tsc; + + tsc = car_get_var(g_timer_tsc); + if (tsc > 0) + return tsc; + + tsc = calibrate_tsc_with_pit(); + + /* Set some semi-ridiculous rate if approximation fails. */ + if (tsc == 0) + tsc = 5000; + + car_set_var(g_timer_tsc, tsc); + return tsc; +} +#endif |