diff options
| -rw-r--r-- | arch/x86/kernel/apb_timer.c | 60 |
1 files changed, 4 insertions, 56 deletions
diff --git a/arch/x86/kernel/apb_timer.c b/arch/x86/kernel/apb_timer.c index 7c9ab59653e..afc406498c9 100644 --- a/arch/x86/kernel/apb_timer.c +++ b/arch/x86/kernel/apb_timer.c @@ -506,64 +506,12 @@ static int apbt_next_event(unsigned long delta, return 0; } -/* - * APB timer clock is not in sync with pclk on Langwell, which translates to - * unreliable read value caused by sampling error. the error does not add up - * overtime and only happens when sampling a 0 as a 1 by mistake. so the time - * would go backwards. the following code is trying to prevent time traveling - * backwards. little bit paranoid. - */ static cycle_t apbt_read_clocksource(struct clocksource *cs) { - unsigned long t0, t1, t2; - static unsigned long last_read; - -bad_count: - t1 = apbt_readl(phy_cs_timer_id, - APBTMR_N_CURRENT_VALUE); - t2 = apbt_readl(phy_cs_timer_id, - APBTMR_N_CURRENT_VALUE); - if (unlikely(t1 < t2)) { - pr_debug("APBT: read current count error %lx:%lx:%lx\n", - t1, t2, t2 - t1); - goto bad_count; - } - /* - * check against cached last read, makes sure time does not go back. - * it could be a normal rollover but we will do tripple check anyway - */ - if (unlikely(t2 > last_read)) { - /* check if we have a normal rollover */ - unsigned long raw_intr_status = - apbt_readl_reg(APBTMRS_RAW_INT_STATUS); - /* - * cs timer interrupt is masked but raw intr bit is set if - * rollover occurs. then we read EOI reg to clear it. - */ - if (raw_intr_status & (1 << phy_cs_timer_id)) { - apbt_readl(phy_cs_timer_id, APBTMR_N_EOI); - goto out; - } - pr_debug("APB CS going back %lx:%lx:%lx ", - t2, last_read, t2 - last_read); -bad_count_x3: - pr_debug("triple check enforced\n"); - t0 = apbt_readl(phy_cs_timer_id, - APBTMR_N_CURRENT_VALUE); - udelay(1); - t1 = apbt_readl(phy_cs_timer_id, - APBTMR_N_CURRENT_VALUE); - udelay(1); - t2 = apbt_readl(phy_cs_timer_id, - APBTMR_N_CURRENT_VALUE); - if ((t2 > t1) || (t1 > t0)) { - printk(KERN_ERR "Error: APB CS tripple check failed\n"); - goto bad_count_x3; - } - } -out: - last_read = t2; - return (cycle_t)~t2; + unsigned long current_count; + + current_count = apbt_readl(phy_cs_timer_id, APBTMR_N_CURRENT_VALUE); + return (cycle_t)~current_count; } static int apbt_clocksource_register(void) |