From bf080041ba1975497bce21138d090a72964d5f1f Mon Sep 17 00:00:00 2001
From: john stultz <johnstul@us.ibm.com>
Date: Fri, 8 Dec 2006 02:36:02 -0800
Subject: [PATCH] --- yaml --- r: 43490 b: refs/heads/master c:
 562f9c574e0707f9159a729ea41faf53b221cd30 h: refs/heads/master v: v3

---
 [refs]                              |  2 +-
 trunk/drivers/clocksource/acpi_pm.c | 36 +++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index ee1d5eb5ac50..8e49a5f71cb4 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: a2ee8649ba6d71416712e798276bf7c40b64e6e5
+refs/heads/master: 562f9c574e0707f9159a729ea41faf53b221cd30
diff --git a/trunk/drivers/clocksource/acpi_pm.c b/trunk/drivers/clocksource/acpi_pm.c
index 7fcb77a9d011..8ab61ef97b4c 100644
--- a/trunk/drivers/clocksource/acpi_pm.c
+++ b/trunk/drivers/clocksource/acpi_pm.c
@@ -142,6 +142,39 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SERVERWORKS, PCI_DEVICE_ID_SERVERWORKS_LE,
 			acpi_pm_check_graylist);
 #endif
 
+#ifndef CONFIG_X86_64
+#include "mach_timer.h"
+#define PMTMR_EXPECTED_RATE \
+  ((CALIBRATE_LATCH * (PMTMR_TICKS_PER_SEC >> 10)) / (CLOCK_TICK_RATE>>10))
+/*
+ * 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;
+}
+#else
+#define verify_pmtmr_rate() (0)
+#endif
 
 static int __init init_acpi_pm_clocksource(void)
 {
@@ -173,6 +206,9 @@ static int __init init_acpi_pm_clocksource(void)
 	return -ENODEV;
 
 pm_good:
+	if (verify_pmtmr_rate() != 0)
+		return -ENODEV;
+
 	return clocksource_register(&clocksource_acpi_pm);
 }