/*
* This was taken from prep_setup.c
* Use the NVRAM RTC to time a second to calibrate the decrementer.
*/
void __init
todc_calibrate_decr(void)
{
ulong freq;
ulong tbl, tbu;
long i, loop_count;
u_char sec;
todc_time_init();
/*
* Actually this is bad for precision, we should have a loop in
* which we only read the seconds counter. todc_read_val writes
* the address bytes on every call and this takes a lot of time.
* Perhaps an nvram_wait_change method returning a time
* stamp with a loop count as parameter would be the solution.
*/
/*
* Need to make sure the tbl doesn't roll over so if tbu increments
* during this test, we need to do it again.
*/
loop_count = 0;
sec = todc_read_timereg(todc_info->seconds) & 0x7f;
do {
tbu = get_tbu();
for (i = 0 ; i < 10000000 ; i++) {/* may take up to 1 second */
tbl = get_tbl();
if ((todc_read_timereg(todc_info->seconds) & 0x7f) != sec) {
break;
}
}
sec = todc_read_timereg(todc_info->seconds) & 0x7f;
for (i = 0 ; i < 10000000 ; i++) { /* Should take 1 second */
freq = get_tbl();
if ((todc_read_timereg(todc_info->seconds) & 0x7f) != sec) {
break;
}
}
freq -= tbl;
} while ((get_tbu() != tbu) && (++loop_count < 2));
printk("time_init: decrementer frequency = %lu.%.6lu MHz\n",
freq/1000000, freq%1000000);
tb_ticks_per_jiffy = freq / HZ;
tb_to_us = mulhwu_scale_factor(freq, 1000000);
return;
}
unsigned long long sched_clock(void)
{
unsigned long lo, hi, hi2;
unsigned long long tb;
if (!__USE_RTC()) {
do {
hi = get_tbu();
lo = get_tbl();
hi2 = get_tbu();
} while (hi2 != hi);
tb = ((unsigned long long) hi << 32) | lo;
tb = (tb * tb_to_ns_scale) >> 10;
} else {
do {
DWORDLONG rdtsc(void)
{
// Original code (returning the cpu cycle counter)
// read 64 bit tbl (time base) using motorola example
DWORD lo, hi1, hi2;
do {
hi1 = get_tbu();
lo = get_tbl();
hi2 = get_tbu();
} while (hi1 != hi2);
return ((DWORDLONG) hi1) << 32 | (DWORDLONG) lo;
}
void __devinit smp_chrp_give_timebase(void)
{
spin_lock(&timebase_lock);
rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
timebase_upper = get_tbu();
timebase_lower = get_tbl();
spin_unlock(&timebase_lock);
while (timebase_upper || timebase_lower)
barrier();
rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
}
