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[PATCH] Allow early access to the power management timer 

Allow early access to the power management timer by exposing the verified read
function and providing a helper function which checks the pmtmr_ioport
variable and returns either the pm timer readout or 0 in case the pm timer is
not available.

Create a new header file and replace also the ifdef'ed extern definition in
arch/i386/kernel/acpi/boot.c

This is a preperatory patch for the rework of the local apic timer
calibration.

No functional changes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Thomas Gleixner 2007-02-16 01:27:57 -08:00 committed by Linus Torvalds
parent 169a0abbe3
commit d66bea57e7
3 changed files with 48 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
arch/i386/kernel/acpi/boot.c
View File

@ -25,6 +25,7 @@
#include <linux/init.h>
#include <linux/acpi.h>
#include <linux/acpi_pmtmr.h>
#include <linux/efi.h>
#include <linux/cpumask.h>
#include <linux/module.h>
@ -676,10 +677,6 @@ static int __init acpi_parse_hpet(struct acpi_table_header *table)
#define acpi_parse_hpet NULL
#endif
#ifdef CONFIG_X86_PM_TIMER
extern u32 pmtmr_ioport;
#endif
static int __init acpi_parse_fadt(struct acpi_table_header *table)
{

17
drivers/clocksource/acpi_pm.c
View File

@ -16,15 +16,13 @@
* This file is licensed under the GPL v2.
*/
#include <linux/acpi_pmtmr.h>
#include <linux/clocksource.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <asm/io.h>
/* Number of PMTMR ticks expected during calibration run */
#define PMTMR_TICKS_PER_SEC 3579545
/*
* The I/O port the PMTMR resides at.
* The location is detected during setup_arch(),
@ -32,15 +30,13 @@
*/
u32 pmtmr_ioport __read_mostly;
#define ACPI_PM_MASK CLOCKSOURCE_MASK(24) /* limit it to 24 bits */
static inline u32 read_pmtmr(void)
{
/* mask the output to 24 bits */
return inl(pmtmr_ioport) & ACPI_PM_MASK;
}
static cycle_t acpi_pm_read_verified(void)
u32 acpi_pm_read_verified(void)
{
u32 v1 = 0, v2 = 0, v3 = 0;
@ -57,7 +53,12 @@ static cycle_t acpi_pm_read_verified(void)
} while (unlikely((v1 > v2 && v1 < v3) || (v2 > v3 && v2 < v1)
|| (v3 > v1 && v3 < v2)));
return (cycle_t)v2;
return v2;
}
static cycle_t acpi_pm_read_slow(void)
{
return (cycle_t)acpi_pm_read_verified();
}
static cycle_t acpi_pm_read(void)
@ -88,7 +89,7 @@ __setup("acpi_pm_good", acpi_pm_good_setup);
static inline void acpi_pm_need_workaround(void)
{
clocksource_acpi_pm.read = acpi_pm_read_verified;
clocksource_acpi_pm.read = acpi_pm_read_slow;
clocksource_acpi_pm.rating = 110;
}

38
include/linux/acpi_pmtmr.h Normal file
View File

@ -0,0 +1,38 @@
#ifndef _ACPI_PMTMR_H_
#define _ACPI_PMTMR_H_
#include <linux/clocksource.h>
/* Number of PMTMR ticks expected during calibration run */
#define PMTMR_TICKS_PER_SEC 3579545
/* limit it to 24 bits */
#define ACPI_PM_MASK CLOCKSOURCE_MASK(24)
/* Overrun value */
#define ACPI_PM_OVRRUN (1<<24)
#ifdef CONFIG_X86_PM_TIMER
extern u32 acpi_pm_read_verified(void);
extern u32 pmtmr_ioport;
static inline u32 acpi_pm_read_early(void)
{
if (!pmtmr_ioport)
return 0;
/* mask the output to 24 bits */
return acpi_pm_read_verified() & ACPI_PM_MASK;
}
#else
static inline u32 acpi_pm_read_early(void)
{
return 0;
}
#endif
#endif