diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86_64/kernel/time.c | 42 |
1 files changed, 28 insertions, 14 deletions
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c index fb8c809b4cd..66bf6ddeb0c 100644 --- a/arch/x86_64/kernel/time.c +++ b/arch/x86_64/kernel/time.c @@ -64,6 +64,7 @@ static int notsc __initdata = 0; unsigned int cpu_khz; /* TSC clocks / usec, not used here */ static unsigned long hpet_period; /* fsecs / HPET clock */ unsigned long hpet_tick; /* HPET clocks / interrupt */ +static int hpet_use_timer; unsigned long vxtime_hz = PIT_TICK_RATE; int report_lost_ticks; /* command line option */ unsigned long long monotonic_base; @@ -105,7 +106,9 @@ static inline unsigned int do_gettimeoffset_tsc(void) static inline unsigned int do_gettimeoffset_hpet(void) { - return ((hpet_readl(HPET_COUNTER) - vxtime.last) * vxtime.quot) >> 32; + /* cap counter read to one tick to avoid inconsistencies */ + unsigned long counter = hpet_readl(HPET_COUNTER) - vxtime.last; + return (min(counter,hpet_tick) * vxtime.quot) >> 32; } unsigned int (*do_gettimeoffset)(void) = do_gettimeoffset_tsc; @@ -301,7 +304,7 @@ unsigned long long monotonic_clock(void) last_offset = vxtime.last; base = monotonic_base; - this_offset = hpet_readl(HPET_T0_CMP) - hpet_tick; + this_offset = hpet_readl(HPET_COUNTER); } while (read_seqretry(&xtime_lock, seq)); offset = (this_offset - last_offset); @@ -377,7 +380,14 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) write_seqlock(&xtime_lock); - if (vxtime.hpet_address) { + if (vxtime.hpet_address) + offset = hpet_readl(HPET_COUNTER); + + if (hpet_use_timer) { + /* if we're using the hpet timer functionality, + * we can more accurately know the counter value + * when the timer interrupt occured. + */ offset = hpet_readl(HPET_T0_CMP) - hpet_tick; delay = hpet_readl(HPET_COUNTER) - offset; } else { @@ -803,17 +813,18 @@ static int hpet_timer_stop_set_go(unsigned long tick) * Set up timer 0, as periodic with first interrupt to happen at hpet_tick, * and period also hpet_tick. */ - - hpet_writel(HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL | + if (hpet_use_timer) { + hpet_writel(HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL | HPET_TN_32BIT, HPET_T0_CFG); - hpet_writel(hpet_tick, HPET_T0_CMP); - hpet_writel(hpet_tick, HPET_T0_CMP); /* AK: why twice? */ - + hpet_writel(hpet_tick, HPET_T0_CMP); + hpet_writel(hpet_tick, HPET_T0_CMP); /* AK: why twice? */ + cfg |= HPET_CFG_LEGACY; + } /* * Go! */ - cfg |= HPET_CFG_ENABLE | HPET_CFG_LEGACY; + cfg |= HPET_CFG_ENABLE; hpet_writel(cfg, HPET_CFG); return 0; @@ -834,8 +845,7 @@ static int hpet_init(void) id = hpet_readl(HPET_ID); - if (!(id & HPET_ID_VENDOR) || !(id & HPET_ID_NUMBER) || - !(id & HPET_ID_LEGSUP)) + if (!(id & HPET_ID_VENDOR) || !(id & HPET_ID_NUMBER)) return -1; hpet_period = hpet_readl(HPET_PERIOD); @@ -845,6 +855,8 @@ static int hpet_init(void) hpet_tick = (1000000000L * (USEC_PER_SEC / HZ) + hpet_period / 2) / hpet_period; + hpet_use_timer = (id & HPET_ID_LEGSUP); + return hpet_timer_stop_set_go(hpet_tick); } @@ -901,9 +913,11 @@ void __init time_init(void) set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec); - if (!hpet_init()) { + if (!hpet_init()) vxtime_hz = (1000000000000000L + hpet_period / 2) / hpet_period; + + if (hpet_use_timer) { cpu_khz = hpet_calibrate_tsc(); timename = "HPET"; #ifdef CONFIG_X86_PM_TIMER @@ -968,7 +982,7 @@ void __init time_init_gtod(void) if (unsynchronized_tsc()) notsc = 1; if (vxtime.hpet_address && notsc) { - timetype = "HPET"; + timetype = hpet_use_timer ? "HPET" : "PIT/HPET"; vxtime.last = hpet_readl(HPET_T0_CMP) - hpet_tick; vxtime.mode = VXTIME_HPET; do_gettimeoffset = do_gettimeoffset_hpet; @@ -983,7 +997,7 @@ void __init time_init_gtod(void) printk(KERN_INFO "Disabling vsyscall due to use of PM timer\n"); #endif } else { - timetype = vxtime.hpet_address ? "HPET/TSC" : "PIT/TSC"; + timetype = hpet_use_timer ? "HPET/TSC" : "PIT/TSC"; vxtime.mode = VXTIME_TSC; } |