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Diffstat (limited to 'arch/x86/kernel/hpet.c')
-rw-r--r--arch/x86/kernel/hpet.c24
1 files changed, 20 insertions, 4 deletions
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index 648b3a2a3a4..81408b93f88 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -236,6 +236,10 @@ static void hpet_stop_counter(void)
unsigned long cfg = hpet_readl(HPET_CFG);
cfg &= ~HPET_CFG_ENABLE;
hpet_writel(cfg, HPET_CFG);
+}
+
+static void hpet_reset_counter(void)
+{
hpet_writel(0, HPET_COUNTER);
hpet_writel(0, HPET_COUNTER + 4);
}
@@ -250,6 +254,7 @@ static void hpet_start_counter(void)
static void hpet_restart_counter(void)
{
hpet_stop_counter();
+ hpet_reset_counter();
hpet_start_counter();
}
@@ -309,7 +314,7 @@ static int hpet_setup_msi_irq(unsigned int irq);
static void hpet_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt, int timer)
{
- unsigned long cfg;
+ unsigned long cfg, cmp, now;
uint64_t delta;
switch (mode) {
@@ -317,12 +322,23 @@ static void hpet_set_mode(enum clock_event_mode mode,
hpet_stop_counter();
delta = ((uint64_t)(NSEC_PER_SEC/HZ)) * evt->mult;
delta >>= evt->shift;
+ now = hpet_readl(HPET_COUNTER);
+ cmp = now + (unsigned long) delta;
cfg = hpet_readl(HPET_Tn_CFG(timer));
/* Make sure we use edge triggered interrupts */
cfg &= ~HPET_TN_LEVEL;
cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC |
HPET_TN_SETVAL | HPET_TN_32BIT;
hpet_writel(cfg, HPET_Tn_CFG(timer));
+ hpet_writel(cmp, HPET_Tn_CMP(timer));
+ udelay(1);
+ /*
+ * HPET on AMD 81xx needs a second write (with HPET_TN_SETVAL
+ * cleared) to T0_CMP to set the period. The HPET_TN_SETVAL
+ * bit is automatically cleared after the first write.
+ * (See AMD-8111 HyperTransport I/O Hub Data Sheet,
+ * Publication # 24674)
+ */
hpet_writel((unsigned long) delta, HPET_Tn_CMP(timer));
hpet_start_counter();
hpet_print_config();
@@ -722,7 +738,7 @@ static int hpet_cpuhp_notify(struct notifier_block *n,
/*
* Clock source related code
*/
-static cycle_t read_hpet(void)
+static cycle_t read_hpet(struct clocksource *cs)
{
return (cycle_t)hpet_readl(HPET_COUNTER);
}
@@ -756,7 +772,7 @@ static int hpet_clocksource_register(void)
hpet_restart_counter();
/* Verify whether hpet counter works */
- t1 = read_hpet();
+ t1 = hpet_readl(HPET_COUNTER);
rdtscll(start);
/*
@@ -770,7 +786,7 @@ static int hpet_clocksource_register(void)
rdtscll(now);
} while ((now - start) < 200000UL);
- if (t1 == read_hpet()) {
+ if (t1 == hpet_readl(HPET_COUNTER)) {
printk(KERN_WARNING
"HPET counter not counting. HPET disabled\n");
return -ENODEV;