/*
* void __init iSeries_calibrate_decr()
*
* Description:
* This routine retrieves the internal processor frequency from the VPD,
* and sets up the kernel timer decrementer based on that value.
*
*/
void __init iSeries_calibrate_decr(void)
{
unsigned long cyclesPerUsec;
struct div_result divres;
/* Compute decrementer (and TB) frequency in cycles/sec */
cyclesPerUsec = ppc_tb_freq / 1000000;
/*
* Set the amount to refresh the decrementer by. This
* is the number of decrementer ticks it takes for
* 1/HZ seconds.
*/
tb_ticks_per_jiffy = ppc_tb_freq / HZ;
#if 0
/* TEST CODE FOR ADJTIME */
tb_ticks_per_jiffy += tb_ticks_per_jiffy / 5000;
/* END OF TEST CODE */
#endif
/*
* tb_ticks_per_sec = freq; would give better accuracy
* but tb_ticks_per_sec = tb_ticks_per_jiffy*HZ; assures
* that jiffies (and xtime) will match the time returned
* by do_gettimeofday.
*/
tb_ticks_per_sec = tb_ticks_per_jiffy * HZ;
tb_ticks_per_usec = cyclesPerUsec;
tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
div128_by_32(1024 * 1024, 0, tb_ticks_per_sec, &divres);
tb_to_xs = divres.result_low;
setup_default_decr();
}
static void iSeries_tb_recal(void)
{
struct div_result divres;
unsigned long titan, tb;
tb = get_tb();
titan = HvCallXm_loadTod();
if ( iSeries_recal_titan ) {
unsigned long tb_ticks = tb - iSeries_recal_tb;
unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;
unsigned long new_tb_ticks_per_sec = (tb_ticks * USEC_PER_SEC)/titan_usec;
unsigned long new_tb_ticks_per_jiffy = (new_tb_ticks_per_sec+(HZ/2))/HZ;
long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;
char sign = '+';
/* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;
if ( tick_diff < 0 ) {
tick_diff = -tick_diff;
sign = '-';
}
if ( tick_diff ) {
if ( tick_diff < tb_ticks_per_jiffy/25 ) {
printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
new_tb_ticks_per_jiffy, sign, tick_diff );
tb_ticks_per_jiffy = new_tb_ticks_per_jiffy;
tb_ticks_per_sec = new_tb_ticks_per_sec;
div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );
do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
tb_to_xs = divres.result_low;
do_gtod.varp->tb_to_xs = tb_to_xs;
}
else {
printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
" new tb_ticks_per_jiffy = %lu\n"
" old tb_ticks_per_jiffy = %lu\n",
new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );
}
}
}
iSeries_recal_titan = titan;
iSeries_recal_tb = tb;
}