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Diffstat (limited to 'arch/x86/kernel/apb_timer.c')
-rw-r--r--arch/x86/kernel/apb_timer.c60
1 files changed, 4 insertions, 56 deletions
diff --git a/arch/x86/kernel/apb_timer.c b/arch/x86/kernel/apb_timer.c
index 51d4e166306..1293c709ee8 100644
--- a/arch/x86/kernel/apb_timer.c
+++ b/arch/x86/kernel/apb_timer.c
@@ -508,64 +508,12 @@ 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)