173 lines
4.2 KiB
C
173 lines
4.2 KiB
C
/*
|
|
* Common functions used across the timers go here
|
|
*/
|
|
|
|
#include <linux/init.h>
|
|
#include <linux/timex.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/jiffies.h>
|
|
#include <linux/module.h>
|
|
|
|
#include <asm/io.h>
|
|
#include <asm/timer.h>
|
|
#include <asm/hpet.h>
|
|
|
|
#include "mach_timer.h"
|
|
|
|
/* ------ Calibrate the TSC -------
|
|
* Return 2^32 * (1 / (TSC clocks per usec)) for do_fast_gettimeoffset().
|
|
* Too much 64-bit arithmetic here to do this cleanly in C, and for
|
|
* accuracy's sake we want to keep the overhead on the CTC speaker (channel 2)
|
|
* output busy loop as low as possible. We avoid reading the CTC registers
|
|
* directly because of the awkward 8-bit access mechanism of the 82C54
|
|
* device.
|
|
*/
|
|
|
|
#define CALIBRATE_TIME (5 * 1000020/HZ)
|
|
|
|
unsigned long calibrate_tsc(void)
|
|
{
|
|
mach_prepare_counter();
|
|
|
|
{
|
|
unsigned long startlow, starthigh;
|
|
unsigned long endlow, endhigh;
|
|
unsigned long count;
|
|
|
|
rdtsc(startlow,starthigh);
|
|
mach_countup(&count);
|
|
rdtsc(endlow,endhigh);
|
|
|
|
|
|
/* Error: ECTCNEVERSET */
|
|
if (count <= 1)
|
|
goto bad_ctc;
|
|
|
|
/* 64-bit subtract - gcc just messes up with long longs */
|
|
__asm__("subl %2,%0\n\t"
|
|
"sbbl %3,%1"
|
|
:"=a" (endlow), "=d" (endhigh)
|
|
:"g" (startlow), "g" (starthigh),
|
|
"0" (endlow), "1" (endhigh));
|
|
|
|
/* Error: ECPUTOOFAST */
|
|
if (endhigh)
|
|
goto bad_ctc;
|
|
|
|
/* Error: ECPUTOOSLOW */
|
|
if (endlow <= CALIBRATE_TIME)
|
|
goto bad_ctc;
|
|
|
|
__asm__("divl %2"
|
|
:"=a" (endlow), "=d" (endhigh)
|
|
:"r" (endlow), "0" (0), "1" (CALIBRATE_TIME));
|
|
|
|
return endlow;
|
|
}
|
|
|
|
/*
|
|
* The CTC wasn't reliable: we got a hit on the very first read,
|
|
* or the CPU was so fast/slow that the quotient wouldn't fit in
|
|
* 32 bits..
|
|
*/
|
|
bad_ctc:
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_HPET_TIMER
|
|
/* ------ Calibrate the TSC using HPET -------
|
|
* Return 2^32 * (1 / (TSC clocks per usec)) for getting the CPU freq.
|
|
* Second output is parameter 1 (when non NULL)
|
|
* Set 2^32 * (1 / (tsc per HPET clk)) for delay_hpet().
|
|
* calibrate_tsc() calibrates the processor TSC by comparing
|
|
* it to the HPET timer of known frequency.
|
|
* Too much 64-bit arithmetic here to do this cleanly in C
|
|
*/
|
|
#define CALIBRATE_CNT_HPET (5 * hpet_tick)
|
|
#define CALIBRATE_TIME_HPET (5 * KERNEL_TICK_USEC)
|
|
|
|
unsigned long __devinit calibrate_tsc_hpet(unsigned long *tsc_hpet_quotient_ptr)
|
|
{
|
|
unsigned long tsc_startlow, tsc_starthigh;
|
|
unsigned long tsc_endlow, tsc_endhigh;
|
|
unsigned long hpet_start, hpet_end;
|
|
unsigned long result, remain;
|
|
|
|
hpet_start = hpet_readl(HPET_COUNTER);
|
|
rdtsc(tsc_startlow, tsc_starthigh);
|
|
do {
|
|
hpet_end = hpet_readl(HPET_COUNTER);
|
|
} while ((hpet_end - hpet_start) < CALIBRATE_CNT_HPET);
|
|
rdtsc(tsc_endlow, tsc_endhigh);
|
|
|
|
/* 64-bit subtract - gcc just messes up with long longs */
|
|
__asm__("subl %2,%0\n\t"
|
|
"sbbl %3,%1"
|
|
:"=a" (tsc_endlow), "=d" (tsc_endhigh)
|
|
:"g" (tsc_startlow), "g" (tsc_starthigh),
|
|
"0" (tsc_endlow), "1" (tsc_endhigh));
|
|
|
|
/* Error: ECPUTOOFAST */
|
|
if (tsc_endhigh)
|
|
goto bad_calibration;
|
|
|
|
/* Error: ECPUTOOSLOW */
|
|
if (tsc_endlow <= CALIBRATE_TIME_HPET)
|
|
goto bad_calibration;
|
|
|
|
ASM_DIV64_REG(result, remain, tsc_endlow, 0, CALIBRATE_TIME_HPET);
|
|
if (remain > (tsc_endlow >> 1))
|
|
result++; /* rounding the result */
|
|
|
|
if (tsc_hpet_quotient_ptr) {
|
|
unsigned long tsc_hpet_quotient;
|
|
|
|
ASM_DIV64_REG(tsc_hpet_quotient, remain, tsc_endlow, 0,
|
|
CALIBRATE_CNT_HPET);
|
|
if (remain > (tsc_endlow >> 1))
|
|
tsc_hpet_quotient++; /* rounding the result */
|
|
*tsc_hpet_quotient_ptr = tsc_hpet_quotient;
|
|
}
|
|
|
|
return result;
|
|
bad_calibration:
|
|
/*
|
|
* the CPU was so fast/slow that the quotient wouldn't fit in
|
|
* 32 bits..
|
|
*/
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
|
|
unsigned long read_timer_tsc(void)
|
|
{
|
|
unsigned long retval;
|
|
rdtscl(retval);
|
|
return retval;
|
|
}
|
|
|
|
|
|
/* calculate cpu_khz */
|
|
void init_cpu_khz(void)
|
|
{
|
|
if (cpu_has_tsc) {
|
|
unsigned long tsc_quotient = calibrate_tsc();
|
|
if (tsc_quotient) {
|
|
/* report CPU clock rate in Hz.
|
|
* The formula is (10^6 * 2^32) / (2^32 * 1 / (clocks/us)) =
|
|
* clock/second. Our precision is about 100 ppm.
|
|
*/
|
|
{ unsigned long eax=0, edx=1000;
|
|
__asm__("divl %2"
|
|
:"=a" (cpu_khz), "=d" (edx)
|
|
:"r" (tsc_quotient),
|
|
"0" (eax), "1" (edx));
|
|
printk("Detected %u.%03u MHz processor.\n",
|
|
cpu_khz / 1000, cpu_khz % 1000);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|