forked from luck/tmp_suning_uos_patched
1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
80 lines
1.8 KiB
C
80 lines
1.8 KiB
C
/* calibrate.c: default delay calibration
|
|
*
|
|
* Excised from init/main.c
|
|
* Copyright (C) 1991, 1992 Linus Torvalds
|
|
*/
|
|
|
|
#include <linux/sched.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/init.h>
|
|
|
|
static unsigned long preset_lpj;
|
|
static int __init lpj_setup(char *str)
|
|
{
|
|
preset_lpj = simple_strtoul(str,NULL,0);
|
|
return 1;
|
|
}
|
|
|
|
__setup("lpj=", lpj_setup);
|
|
|
|
/*
|
|
* This is the number of bits of precision for the loops_per_jiffy. Each
|
|
* bit takes on average 1.5/HZ seconds. This (like the original) is a little
|
|
* better than 1%
|
|
*/
|
|
#define LPS_PREC 8
|
|
|
|
void __devinit calibrate_delay(void)
|
|
{
|
|
unsigned long ticks, loopbit;
|
|
int lps_precision = LPS_PREC;
|
|
|
|
if (preset_lpj) {
|
|
loops_per_jiffy = preset_lpj;
|
|
printk("Calibrating delay loop (skipped)... "
|
|
"%lu.%02lu BogoMIPS preset\n",
|
|
loops_per_jiffy/(500000/HZ),
|
|
(loops_per_jiffy/(5000/HZ)) % 100);
|
|
} else {
|
|
loops_per_jiffy = (1<<12);
|
|
|
|
printk(KERN_DEBUG "Calibrating delay loop... ");
|
|
while ((loops_per_jiffy <<= 1) != 0) {
|
|
/* wait for "start of" clock tick */
|
|
ticks = jiffies;
|
|
while (ticks == jiffies)
|
|
/* nothing */;
|
|
/* Go .. */
|
|
ticks = jiffies;
|
|
__delay(loops_per_jiffy);
|
|
ticks = jiffies - ticks;
|
|
if (ticks)
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Do a binary approximation to get loops_per_jiffy set to
|
|
* equal one clock (up to lps_precision bits)
|
|
*/
|
|
loops_per_jiffy >>= 1;
|
|
loopbit = loops_per_jiffy;
|
|
while (lps_precision-- && (loopbit >>= 1)) {
|
|
loops_per_jiffy |= loopbit;
|
|
ticks = jiffies;
|
|
while (ticks == jiffies)
|
|
/* nothing */;
|
|
ticks = jiffies;
|
|
__delay(loops_per_jiffy);
|
|
if (jiffies != ticks) /* longer than 1 tick */
|
|
loops_per_jiffy &= ~loopbit;
|
|
}
|
|
|
|
/* Round the value and print it */
|
|
printk("%lu.%02lu BogoMIPS (lpj=%lu)\n",
|
|
loops_per_jiffy/(500000/HZ),
|
|
(loops_per_jiffy/(5000/HZ)) % 100,
|
|
loops_per_jiffy);
|
|
}
|
|
|
|
}
|