From: Neil Horman <nhorman@redhat.com>
Date: Fri, 5 Dec 2008 15:36:55 -0500
Subject: [x86] disable hpet on machine_crash_shutdown
Message-id: 20081205203655.GJ24448@hmsendeavour.rdu.redhat.com
O-Subject: [RHEL5] patch: disable hpet on machine_crash_shutdown (bz 473038)
Bugzilla: 473038
RH-Acked-by: Brian Maly <bmaly@redhat.com>
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>

Hey all-
	This is a backport of upstream commit
0c1b2724069951b1902373e688042b2ec382f68f.  It disables the hpet timer on kdump
shutdown so as to prevent it from hanging the system during kdump reboot.
Verified to fix bz 473038 on at least some of the systems listed (there are
several).  Some of the listed systems still require the gart patch from bz
473166 which dchapman is working on.

Regards
Neil

diff --git a/arch/i386/kernel/crash.c b/arch/i386/kernel/crash.c
index 615878f..0af4062 100644
--- a/arch/i386/kernel/crash.c
+++ b/arch/i386/kernel/crash.c
@@ -22,6 +22,7 @@
 #include <asm/nmi.h>
 #include <asm/hw_irq.h>
 #include <asm/apic.h>
+#include <asm/hpet.h>
 #include <mach_ipi.h>
 
 
@@ -178,6 +179,9 @@ void machine_crash_shutdown(struct pt_regs *regs)
 #if defined(CONFIG_X86_IO_APIC)
 	disable_IO_APIC();
 #endif
+#ifdef CONFIG_HPET_TIMER
+	hpet_disable();
+#endif
 #endif /* CONFIG_XEN */
 	crash_save_self(regs);
 }
diff --git a/arch/i386/kernel/time_hpet.c b/arch/i386/kernel/time_hpet.c
index cf206c8..6f3989a 100644
--- a/arch/i386/kernel/time_hpet.c
+++ b/arch/i386/kernel/time_hpet.c
@@ -236,6 +236,19 @@ int is_hpet_capable(void)
 	return 0;
 }
 
+void hpet_disable(void)
+{
+        if (is_hpet_capable()) {
+                unsigned long cfg = hpet_readl(HPET_CFG);
+
+                if (is_hpet_legacy_int_enabled()) {
+                        cfg &= ~HPET_CFG_LEGACY;
+                }
+                cfg &= ~HPET_CFG_ENABLE;
+                hpet_writel(cfg, HPET_CFG);
+        }
+}
+
 static int __init hpet_setup(char* str)
 {
 	if (str) {
diff --git a/arch/x86_64/kernel/crash.c b/arch/x86_64/kernel/crash.c
index 178fb47..a66fc8e 100644
--- a/arch/x86_64/kernel/crash.c
+++ b/arch/x86_64/kernel/crash.c
@@ -22,6 +22,7 @@
 #include <asm/hardirq.h>
 #include <asm/nmi.h>
 #include <asm/hw_irq.h>
+#include <asm/hpet.h>
 #include <asm/mach_apic.h>
 
 /* This keeps a track of which one is crashing cpu. */
@@ -161,6 +162,9 @@ static void nmi_shootdown_cpus(void)
 
 void machine_crash_shutdown(struct pt_regs *regs)
 {
+#ifdef CONFIG_HPET_TIMER
+	unsigned long cfg;
+#endif
 	/*
 	 * This function is only called after the system
 	 * has panicked or is otherwise in a critical state.
@@ -185,6 +189,12 @@ void machine_crash_shutdown(struct pt_regs *regs)
 #if defined(CONFIG_X86_IO_APIC)
 	disable_IO_APIC();
 #endif
+#ifdef CONFIG_HPET_TIMER
+	cfg = hpet_readl(HPET_CFG);
+	cfg &= ~HPET_CFG_LEGACY;
+	cfg &= ~HPET_CFG_ENABLE;
+	hpet_writel(cfg, HPET_CFG);
+#endif
 #endif /* CONFIG_XEN */
 	crash_save_self(regs);
 }
diff --git a/include/asm-i386/hpet.h b/include/asm-i386/hpet.h
index c72ffa7..969e5df 100644
--- a/include/asm-i386/hpet.h
+++ b/include/asm-i386/hpet.h
@@ -96,6 +96,7 @@ extern int hpet_use_timer;
 
 extern int hpet_rtc_timer_init(void);
 extern int hpet_enable(void);
+extern void hpet_disable(void);
 extern int hpet_reenable(void);
 extern int is_hpet_enabled(void);
 extern int is_hpet_legacy_int_enabled(void);