X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fi386%2Fkernel%2Ftimers%2Ftimer_pm.c;h=737a0219d1937ce4f5273941d00852bd390cd164;hb=9bf4aaab3e101692164d49b7ca357651eb691cb6;hp=7aa63c9b8e18f3de62650e2c1ef97e08b8bfaeed;hpb=db216c3d5e4c040e557a50f8f5d35d5c415e8c1c;p=linux-2.6.git

diff --git a/arch/i386/kernel/timers/timer_pm.c b/arch/i386/kernel/timers/timer_pm.c
index 7aa63c9b8..737a0219d 100644
--- a/arch/i386/kernel/timers/timer_pm.c
+++ b/arch/i386/kernel/timers/timer_pm.c
@@ -21,6 +21,14 @@
 #include <asm/io.h>
 #include <asm/arch_hooks.h>
 
+#include <linux/timex.h>
+#include "mach_timer.h"
+
+/* Number of PMTMR ticks expected during calibration run */
+#define PMTMR_TICKS_PER_SEC 3579545
+#define PMTMR_EXPECTED_RATE \
+  ((CALIBRATE_LATCH * (PMTMR_TICKS_PER_SEC >> 10)) / (CLOCK_TICK_RATE>>10))
+
 
 /* The I/O port the PMTMR resides at.
  * The location is detected during setup_arch(),
@@ -57,6 +65,33 @@ static inline u32 read_pmtmr(void)
 	return v2 & ACPI_PM_MASK;
 }
 
+
+/*
+ * Some boards have the PMTMR running way too fast. We check
+ * the PMTMR rate against PIT channel 2 to catch these cases.
+ */
+static int verify_pmtmr_rate(void)
+{
+	u32 value1, value2;
+	unsigned long count, delta;
+
+	mach_prepare_counter();
+	value1 = read_pmtmr();
+	mach_countup(&count);
+	value2 = read_pmtmr();
+	delta = (value2 - value1) & ACPI_PM_MASK;
+
+	/* Check that the PMTMR delta is within 5% of what we expect */
+	if (delta < (PMTMR_EXPECTED_RATE * 19) / 20 ||
+	    delta > (PMTMR_EXPECTED_RATE * 21) / 20) {
+		printk(KERN_INFO "PM-Timer running at invalid rate: %lu%% of normal - aborting.\n", 100UL * delta / PMTMR_EXPECTED_RATE);
+		return -1;
+	}
+
+	return 0;
+}
+
+
 static int init_pmtmr(char* override)
 {
 	u32 value1, value2;
@@ -89,6 +124,9 @@ static int init_pmtmr(char* override)
 	return -ENODEV;
 
 pm_good:
+	if (verify_pmtmr_rate() != 0)
+		return -ENODEV;
+
 	init_cpu_khz();
 	return 0;
 }