linux-kernel - [PATCH] x86: disable hpet legacy replacement for kexec

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Message-ID: <87sl2s4ran.fsf@duaron.myhome.or.jp>
Date:	Tue, 27 Nov 2007 06:42:40 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH] x86: disable hpet legacy replacement for kexec

Hi,

This seems to introduced after 2.6.23, so if possible, I'd like to fix
before 2.6.24. What do you think the following?

Thanks.
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>


If HPET was enabled by pci quirks, we use i8253 as initial clockevent
because pci quirks doesn't run until pci is initialized.

The above means the kernel (or something) is assuming HPET legacy
replacement is disabled and can use i8253 at boot.

If we used kexec, it isn't true. So, this patch disables HPET legacy
replacement for kexec in machine_shutdown().

Signed-off-by: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
---

 arch/x86/kernel/hpet.c      |   14 ++++++++++++++
 arch/x86/kernel/reboot_32.c |    4 ++++
 arch/x86/kernel/reboot_64.c |    4 ++++
 include/asm-x86/hpet.h      |    1 +
 4 files changed, 23 insertions(+)

diff -puN arch/x86/kernel/hpet.c~kexec-need-to-disable-hpet arch/x86/kernel/hpet.c
--- linux-2.6/arch/x86/kernel/hpet.c~kexec-need-to-disable-hpet	2007-11-24 09:38:23.000000000 +0900
+++ linux-2.6-hirofumi/arch/x86/kernel/hpet.c	2007-11-27 04:57:00.000000000 +0900
@@ -446,6 +446,20 @@ static __init int hpet_late_init(void)
 }
 fs_initcall(hpet_late_init);
 
+void hpet_disable(void)
+{
+	if (is_hpet_capable()) {
+		unsigned long cfg = hpet_readl(HPET_CFG);
+
+		if (hpet_legacy_int_enabled) {
+			cfg &= ~HPET_CFG_LEGACY;
+			hpet_legacy_int_enabled = 0;
+		}
+		cfg &= ~HPET_CFG_ENABLE;
+		hpet_writel(cfg, HPET_CFG);
+	}
+}
+
 #ifdef CONFIG_HPET_EMULATE_RTC
 
 /* HPET in LegacyReplacement Mode eats up RTC interrupt line. When, HPET
diff -puN arch/x86/kernel/reboot_32.c~kexec-need-to-disable-hpet arch/x86/kernel/reboot_32.c
--- linux-2.6/arch/x86/kernel/reboot_32.c~kexec-need-to-disable-hpet	2007-11-24 09:38:23.000000000 +0900
+++ linux-2.6-hirofumi/arch/x86/kernel/reboot_32.c	2007-11-27 04:57:50.000000000 +0900
@@ -11,6 +11,7 @@
 #include <linux/reboot.h>
 #include <asm/uaccess.h>
 #include <asm/apic.h>
+#include <asm/hpet.h>
 #include <asm/desc.h>
 #include "mach_reboot.h"
 #include <asm/reboot_fixups.h>
@@ -326,6 +327,9 @@ static void native_machine_shutdown(void
 #ifdef CONFIG_X86_IO_APIC
 	disable_IO_APIC();
 #endif
+#ifdef CONFIG_HPET_TIMER
+	hpet_disable();
+#endif
 }
 
 void __attribute__((weak)) mach_reboot_fixups(void)
diff -puN arch/x86/kernel/reboot_64.c~kexec-need-to-disable-hpet arch/x86/kernel/reboot_64.c
--- linux-2.6/arch/x86/kernel/reboot_64.c~kexec-need-to-disable-hpet	2007-11-24 09:38:23.000000000 +0900
+++ linux-2.6-hirofumi/arch/x86/kernel/reboot_64.c	2007-11-27 04:57:56.000000000 +0900
@@ -17,6 +17,7 @@
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 #include <asm/apic.h>
+#include <asm/hpet.h>
 #include <asm/gart.h>
 
 /*
@@ -113,6 +114,9 @@ void machine_shutdown(void)
 
 	disable_IO_APIC();
 
+#ifdef CONFIG_HPET_TIMER
+	hpet_disable();
+#endif
 	local_irq_restore(flags);
 
 	pci_iommu_shutdown();
diff -puN include/asm-x86/hpet.h~kexec-need-to-disable-hpet include/asm-x86/hpet.h
--- linux-2.6/include/asm-x86/hpet.h~kexec-need-to-disable-hpet	2007-11-24 09:38:23.000000000 +0900
+++ linux-2.6-hirofumi/include/asm-x86/hpet.h	2007-11-27 04:54:32.000000000 +0900
@@ -61,6 +61,7 @@ extern unsigned long force_hpet_address;
 extern int hpet_force_user;
 extern int is_hpet_enabled(void);
 extern int hpet_enable(void);
+extern void hpet_disable(void);
 extern unsigned long hpet_readl(unsigned long a);
 extern void force_hpet_resume(void);
 
_
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