diff options
Diffstat (limited to 'sys/alpha/alpha/clock.c')
| -rw-r--r-- | sys/alpha/alpha/clock.c | 67 |
1 files changed, 63 insertions, 4 deletions
diff --git a/sys/alpha/alpha/clock.c b/sys/alpha/alpha/clock.c index f2a8a53..0884881 100644 --- a/sys/alpha/alpha/clock.c +++ b/sys/alpha/alpha/clock.c @@ -1,4 +1,4 @@ -/* $Id: clock.c,v 1.7 1999/04/23 19:53:37 dt Exp $ */ +/* $Id: clock.c,v 1.8 1999/04/25 10:45:59 dt Exp $ */ /* $NetBSD: clock.c,v 1.20 1998/01/31 10:32:47 ross Exp $ */ /* @@ -114,6 +114,7 @@ static u_int32_t max_cycles_per_tick; static u_int32_t last_time; static void handleclock(void* arg); +static u_int32_t calibrate_clocks(u_int32_t firmware_freq); void clockattach(device_t dev) @@ -125,6 +126,7 @@ clockattach(device_t dev) if (clockdev) panic("clockattach: multiple clocks"); clockdev = dev; + cycles_per_sec = calibrate_clocks(cycles_per_sec); #ifdef EVCNT_COUNTERS evcnt_attach(dev, "intr", &clock_intr_evcnt); #endif @@ -150,6 +152,8 @@ clockattach(device_t dev) void cpu_initclocks() { + u_int32_t freq; + if (clockdev == NULL) panic("cpu_initclocks: no clock attached"); @@ -175,11 +179,12 @@ cpu_initclocks() * hardclock, which would then fall over because p->p_stats * isn't set at that time. */ + freq = cycles_per_sec; last_time = alpha_rpcc(); - scaled_ticks_per_cycle = ((u_int64_t)hz << FIX_SHIFT) / cycles_per_sec; - max_cycles_per_tick = 2*cycles_per_sec / hz; + scaled_ticks_per_cycle = ((u_int64_t)hz << FIX_SHIFT) / freq; + max_cycles_per_tick = 2*freq / hz; - alpha_timecounter.tc_frequency = cycles_per_sec; + alpha_timecounter.tc_frequency = freq; init_timecounter(&alpha_timecounter); platform.clockintr = (void (*) __P((void *))) handleclock; @@ -190,6 +195,60 @@ cpu_initclocks() CLOCK_INIT(clockdev); } +static u_int32_t +calibrate_clocks(u_int32_t firmware_freq) +{ + u_int32_t start_pcc, stop_pcc; + int sec, start_sec; + + if (bootverbose) + printf("Calibrating clock(s) ... "); + + /* Read the mc146818A seconds counter. */ + if (CLOCK_GETSECS(clockdev, &sec)) + goto fail; + + /* Wait for the mC146818A seconds counter to change. */ + start_sec = sec; + for (;;) { + if (CLOCK_GETSECS(clockdev, &sec)) + goto fail; + if (sec != start_sec) + break; + } + + /* Start keeping track of the PCC. */ + start_pcc = alpha_rpcc(); + + /* + * Wait for the mc146818A seconds counter to change. + */ + start_sec = sec; + for (;;) { + if (CLOCK_GETSECS(clockdev, &sec)) + goto fail; + if (sec != start_sec) + break; + } + + /* + * Read the PCC again to work out frequency. + */ + stop_pcc = alpha_rpcc(); + + if (bootverbose) { + printf("PCC clock: %u Hz (firmware %u Hz)\n", + stop_pcc - start_pcc, firmware_freq); + } + return (stop_pcc - start_pcc); + +fail: + if (bootverbose) + printf("failed, using firmware default of %u Hz\n", + firmware_freq); + return (firmware_freq); +} + static void handleclock(void* arg) { |
