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authorLinus Torvalds <torvalds@linux-foundation.org>2011-03-15 23:01:36 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2011-03-15 23:01:36 -0400
commitd10902812c9cd5583130a4ebb9ad19c60b68149d (patch)
treeb1b28587970e8cebf74ba4d61edf49537f619ab7 /arch/x86/kernel/apb_timer.c
parent181f977d134a9f8e3f8839f42af655b045fc059e (diff)
parent25874a299ef8037df03ce4ada570bc4e42f9748f (diff)
Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (27 commits) x86: Clean up apic.c and apic.h x86: Remove superflous goal definition of tsc_sync x86: dt: Correct local apic documentation in device tree bindings x86: dt: Cleanup local apic setup x86: dt: Fix OLPC=y/INTEL_CE=n build rtc: cmos: Add OF bindings x86: ce4100: Use OF to setup devices x86: ioapic: Add OF bindings for IO_APIC x86: dtb: Add generic bus probe x86: dtb: Add support for PCI devices backed by dtb nodes x86: dtb: Add device tree support for HPET x86: dtb: Add early parsing of IO_APIC x86: dtb: Add irq domain abstraction x86: dtb: Add a device tree for CE4100 x86: Add device tree support x86: e820: Remove conditional early mapping in parse_e820_ext x86: OLPC: Make OLPC=n build again x86: OLPC: Remove extra OLPC_OPENFIRMWARE_DT indirection x86: OLPC: Cleanup config maze completely x86: OLPC: Hide OLPC_OPENFIRMWARE config switch ... Fix up conflicts in arch/x86/platform/ce4100/ce4100.c
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 51d4e1663066..1293c709ee85 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,
508 return 0; 508 return 0;
509} 509}
510 510
511/*
512 * APB timer clock is not in sync with pclk on Langwell, which translates to
513 * unreliable read value caused by sampling error. the error does not add up
514 * overtime and only happens when sampling a 0 as a 1 by mistake. so the time
515 * would go backwards. the following code is trying to prevent time traveling
516 * backwards. little bit paranoid.
517 */
518static cycle_t apbt_read_clocksource(struct clocksource *cs) 511static cycle_t apbt_read_clocksource(struct clocksource *cs)
519{ 512{
520 unsigned long t0, t1, t2; 513 unsigned long current_count;
521 static unsigned long last_read; 514
522 515 current_count = apbt_readl(phy_cs_timer_id, APBTMR_N_CURRENT_VALUE);
523bad_count: 516 return (cycle_t)~current_count;
524 t1 = apbt_readl(phy_cs_timer_id,
525 APBTMR_N_CURRENT_VALUE);
526 t2 = apbt_readl(phy_cs_timer_id,
527 APBTMR_N_CURRENT_VALUE);
528 if (unlikely(t1 < t2)) {
529 pr_debug("APBT: read current count error %lx:%lx:%lx\n",
530 t1, t2, t2 - t1);
531 goto bad_count;
532 }
533 /*
534 * check against cached last read, makes sure time does not go back.
535 * it could be a normal rollover but we will do tripple check anyway
536 */
537 if (unlikely(t2 > last_read)) {
538 /* check if we have a normal rollover */
539 unsigned long raw_intr_status =
540 apbt_readl_reg(APBTMRS_RAW_INT_STATUS);
541 /*
542 * cs timer interrupt is masked but raw intr bit is set if
543 * rollover occurs. then we read EOI reg to clear it.
544 */
545 if (raw_intr_status & (1 << phy_cs_timer_id)) {
546 apbt_readl(phy_cs_timer_id, APBTMR_N_EOI);
547 goto out;
548 }
549 pr_debug("APB CS going back %lx:%lx:%lx ",
550 t2, last_read, t2 - last_read);
551bad_count_x3:
552 pr_debug("triple check enforced\n");
553 t0 = apbt_readl(phy_cs_timer_id,
554 APBTMR_N_CURRENT_VALUE);
555 udelay(1);
556 t1 = apbt_readl(phy_cs_timer_id,
557 APBTMR_N_CURRENT_VALUE);
558 udelay(1);
559 t2 = apbt_readl(phy_cs_timer_id,
560 APBTMR_N_CURRENT_VALUE);
561 if ((t2 > t1) || (t1 > t0)) {
562 printk(KERN_ERR "Error: APB CS tripple check failed\n");
563 goto bad_count_x3;
564 }
565 }
566out:
567 last_read = t2;
568 return (cycle_t)~t2;
569} 517}
570 518
571static int apbt_clocksource_register(void) 519static int apbt_clocksource_register(void)