Commit abb2ed85 authored by Alan Cox's avatar Alan Cox Committed by Linus Torvalds

[PATCH] generalise PIT usage in tsc code, plus tsc sync

parent 535f2150
......@@ -15,6 +15,9 @@
/* processor.h for distable_tsc flag */
#include <asm/processor.h>
#include "io_ports.h"
#include "mach_timer.h"
int tsc_disable __initdata = 0;
extern spinlock_t i8253_lock;
......@@ -57,6 +60,8 @@ static inline unsigned long long cycles_2_ns(unsigned long long cyc)
}
static int count2; /* counter for mark_offset_tsc() */
/* Cached *multiplier* to convert TSC counts to microseconds.
* (see the equation below).
* Equal to 2^32 * (1 / (clocks per usec) ).
......@@ -114,7 +119,7 @@ static void mark_offset_tsc(void)
{
int count;
int countmp;
static int count1=0, count2=LATCH;
static int count1 = 0;
unsigned long long this_offset, last_offset;
write_lock(&monotonic_lock);
......@@ -136,10 +141,10 @@ static void mark_offset_tsc(void)
rdtsc(last_tsc_low, last_tsc_high);
spin_lock(&i8253_lock);
outb_p(0x00, 0x43); /* latch the count ASAP */
outb_p(0x00, PIT_MODE); /* latch the count ASAP */
count = inb_p(0x40); /* read the latched count */
count |= inb(0x40) << 8;
count = inb_p(PIT_CH0); /* read the latched count */
count |= inb(PIT_CH0) << 8;
spin_unlock(&i8253_lock);
if (pit_latch_buggy) {
......@@ -187,26 +192,11 @@ static void delay_tsc(unsigned long loops)
* device.
*/
#define CALIBRATE_LATCH (5 * LATCH)
#define CALIBRATE_TIME (5 * 1000020/HZ)
unsigned long __init calibrate_tsc(void)
{
/* Set the Gate high, disable speaker */
outb((inb(0x61) & ~0x02) | 0x01, 0x61);
/*
* Now let's take care of CTC channel 2
*
* Set the Gate high, program CTC channel 2 for mode 0,
* (interrupt on terminal count mode), binary count,
* load 5 * LATCH count, (LSB and MSB) to begin countdown.
*
* Some devices need a delay here.
*/
outb(0xb0, 0x43); /* binary, mode 0, LSB/MSB, Ch 2 */
outb_p(CALIBRATE_LATCH & 0xff, 0x42); /* LSB of count */
outb_p(CALIBRATE_LATCH >> 8, 0x42); /* MSB of count */
mach_prepare_counter();
{
unsigned long startlow, starthigh;
......@@ -214,10 +204,7 @@ unsigned long __init calibrate_tsc(void)
unsigned long count;
rdtsc(startlow,starthigh);
count = 0;
do {
count++;
} while ((inb(0x61) & 0x20) == 0);
mach_countup(&count);
rdtsc(endlow,endhigh);
last_tsc_low = endlow;
......@@ -340,6 +327,8 @@ static int __init init_tsc(char* override)
cpufreq_register_notifier(&time_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
#endif
count2 = LATCH; /* initialize counter for mark_offset_tsc() */
if (cpu_has_tsc) {
unsigned long tsc_quotient = calibrate_tsc();
if (tsc_quotient) {
......
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