[PATCH] Time: i386 Conversion - part 2: Rework TSC Support

As part of the i386 conversion to the generic timekeeping infrastructure, this
introduces a new tsc.c file.  The code in this file replaces the TSC
initialization, management and access code currently in timer_tsc.c (which
will be removed) that we want to preserve.

The code also introduces the following functionality:

o tsc_khz: like cpu_khz but stores the TSC frequency on systems that do not
  change TSC frequency w/ CPU frequency

o check/mark_tsc_unstable: accessor/modifier flag for TSC timekeeping
  usability

o minor cleanups to calibration math.

This patch also includes a one line __cpuinitdata fix from Zwane Mwaikambo.

Signed-off-by: John Stultz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
john stultz 2006-06-26 00:25:10 -07:00 • committed by Linus Torvalds
commit 539eb11e6e
10 changed files with 389 additions and 217 deletions

View file

@ -15,7 +15,9 @@
#ifndef _MACH_TIMER_H
#define _MACH_TIMER_H
#define CALIBRATE_LATCH (5 * LATCH)
#define CALIBRATE_TIME_MSEC 30 /* 30 msecs */
#define CALIBRATE_LATCH \
((CLOCK_TICK_RATE * CALIBRATE_TIME_MSEC + 1000/2)/1000)
static inline void mach_prepare_counter(void)
{

View file

@ -2,6 +2,7 @@
#define __ASM_MACH_MPPARSE_H
#include <mach_apic.h>
#include <asm/tsc.h>
extern int use_cyclone;
@ -29,6 +30,7 @@ static inline int mps_oem_check(struct mp_config_table *mpc, char *oem,
(!strncmp(productid, "VIGIL SMP", 9)
|| !strncmp(productid, "EXA", 3)
|| !strncmp(productid, "RUTHLESS SMP", 12))){
mark_tsc_unstable();
use_cyclone = 1; /*enable cyclone-timer*/
setup_summit();
return 1;
@ -42,6 +44,7 @@ static inline int acpi_madt_oem_check(char *oem_id, char *oem_table_id)
if (!strncmp(oem_id, "IBM", 3) &&
(!strncmp(oem_table_id, "SERVIGIL", 8)
|| !strncmp(oem_table_id, "EXA", 3))){
mark_tsc_unstable();
use_cyclone = 1; /*enable cyclone-timer*/
setup_summit();
return 1;

View file

@ -7,6 +7,7 @@
#define _ASMi386_TIMEX_H
#include <asm/processor.h>
#include <asm/tsc.h>
#ifdef CONFIG_X86_ELAN
# define CLOCK_TICK_RATE 1189200 /* AMD Elan has different frequency! */
@ -15,39 +16,6 @@
#endif
/*
* Standard way to access the cycle counter on i586+ CPUs.
* Currently only used on SMP.
*
* If you really have a SMP machine with i486 chips or older,
* compile for that, and this will just always return zero.
* That's ok, it just means that the nicer scheduling heuristics
* won't work for you.
*
* We only use the low 32 bits, and we'd simply better make sure
* that we reschedule before that wraps. Scheduling at least every
* four billion cycles just basically sounds like a good idea,
* regardless of how fast the machine is.
*/
typedef unsigned long long cycles_t;
static inline cycles_t get_cycles (void)
{
unsigned long long ret=0;
#ifndef CONFIG_X86_TSC
if (!cpu_has_tsc)
return 0;
#endif
#if defined(CONFIG_X86_GENERIC) || defined(CONFIG_X86_TSC)
rdtscll(ret);
#endif
return ret;
}
extern unsigned int cpu_khz;
extern int read_current_timer(unsigned long *timer_value);
#define ARCH_HAS_READ_CURRENT_TIMER 1

49
include/asm-i386/tsc.h Normal file
View file

@ -0,0 +1,49 @@
/*
* linux/include/asm-i386/tsc.h
*
* i386 TSC related functions
*/
#ifndef _ASM_i386_TSC_H
#define _ASM_i386_TSC_H
#include <linux/config.h>
#include <asm/processor.h>
/*
* Standard way to access the cycle counter on i586+ CPUs.
* Currently only used on SMP.
*
* If you really have a SMP machine with i486 chips or older,
* compile for that, and this will just always return zero.
* That's ok, it just means that the nicer scheduling heuristics
* won't work for you.
*
* We only use the low 32 bits, and we'd simply better make sure
* that we reschedule before that wraps. Scheduling at least every
* four billion cycles just basically sounds like a good idea,
* regardless of how fast the machine is.
*/
typedef unsigned long long cycles_t;
extern unsigned int cpu_khz;
extern unsigned int tsc_khz;
static inline cycles_t get_cycles(void)
{
unsigned long long ret = 0;
#ifndef CONFIG_X86_TSC
if (!cpu_has_tsc)
return 0;
#endif
#if defined(CONFIG_X86_GENERIC) || defined(CONFIG_X86_TSC)
rdtscll(ret);
#endif
return ret;
}
extern void tsc_init(void);
extern void mark_tsc_unstable(void);
#endif