x86: HPET force enable o ICH7 and later
Force detect and/or enable HPET on ICH chipsets. This patch just handles the
detection part and following patches use this information. Adds a function to
repeat the force enabling during resume time.
Using HPET this way, instead of PIT increases the time CPUs can reside in
C-state when system is totally idle. On my test system with Core 2 Duo,
average C-state residency goes up from ~20mS to ~80mS.
[ Build fixed from Andrew Morton ]
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/asm-x86/hpet.h b/include/asm-x86/hpet.h
index 64446a9..7c93324 100644
--- a/include/asm-x86/hpet.h
+++ b/include/asm-x86/hpet.h
@@ -66,6 +66,7 @@
extern int is_hpet_enabled(void);
extern int hpet_enable(void);
extern unsigned long hpet_readl(unsigned long a);
+extern void ich_force_hpet_resume(void);
#ifdef CONFIG_HPET_EMULATE_RTC