static void setup_APIC_timer(unsigned int clocks)
{
unsigned long flags;
local_irq_save(flags);
/*
* Wait for IRQ0's slice:
*/
wait_timer_tick();
__setup_APIC_LVTT(clocks);
local_irq_restore(flags);
}
int __init calibrate_APIC_clock(void)
{
unsigned long long t1 = 0, t2 = 0;
long tt1, tt2;
long result;
int i;
const int LOOPS = HZ/10;
apic_printk(APIC_VERBOSE, "calibrating APIC timer ...\n");
/*
* Put whatever arbitrary (but long enough) timeout
* value into the APIC clock, we just want to get the
* counter running for calibration.
*/
__setup_APIC_LVTT(1000000000);
/*
* The timer chip counts down to zero. Let's wait
* for a wraparound to start exact measurement:
* (the current tick might have been already half done)
*/
wait_timer_tick();
/*
* We wrapped around just now. Let's start:
*/
if (cpu_has_tsc)
rdtscll(t1);
tt1 = apic_read(APIC_TMCCT);
/*
* Let's wait LOOPS wraprounds:
*/
for (i = 0; i < LOOPS; i++)
wait_timer_tick();
tt2 = apic_read(APIC_TMCCT);
if (cpu_has_tsc)
rdtscll(t2);
/*
* The APIC bus clock counter is 32 bits only, it
* might have overflown, but note that we use signed
* longs, thus no extra care needed.
*
* underflown to be exact, as the timer counts down ;)
*/
result = (tt1-tt2)*APIC_DIVISOR/LOOPS;
if (cpu_has_tsc)
apic_printk(APIC_VERBOSE, "..... CPU clock speed is "
"%ld.%04ld MHz.\n",
((long)(t2-t1)/LOOPS)/(1000000/HZ),
((long)(t2-t1)/LOOPS)%(1000000/HZ));
apic_printk(APIC_VERBOSE, "..... host bus clock speed is "
"%ld.%04ld MHz.\n",
result/(1000000/HZ),
result%(1000000/HZ));
return result;
}
static int __init calibrate_APIC_clock(void)
{
unsigned long long t1 = 0, t2 = 0;
long tt1, tt2;
long result;
int i;
unsigned long bus_freq; /* KAF: pointer-size avoids compile warns. */
u32 bus_cycle; /* length of one bus cycle in pico-seconds */
const int LOOPS = HZ/10;
apic_printk(APIC_VERBOSE, "calibrating APIC timer ...\n");
/*
* Put whatever arbitrary (but long enough) timeout
* value into the APIC clock, we just want to get the
* counter running for calibration.
*/
__setup_APIC_LVTT(1000000000);
/*
* The timer chip counts down to zero. Let's wait
* for a wraparound to start exact measurement:
* (the current tick might have been already half done)
*/
wait_timer_tick();
/*
* We wrapped around just now. Let's start:
*/
if (cpu_has_tsc)
rdtscll(t1);
tt1 = apic_read(APIC_TMCCT);
/*
* Let's wait LOOPS wraprounds:
*/
for (i = 0; i < LOOPS; i++)
wait_timer_tick();
tt2 = apic_read(APIC_TMCCT);
if (cpu_has_tsc)
rdtscll(t2);
/*
* The APIC bus clock counter is 32 bits only, it
* might have overflown, but note that we use signed
* longs, thus no extra care needed.
*
* underflown to be exact, as the timer counts down ;)
*/
result = (tt1-tt2)*APIC_DIVISOR/LOOPS;
if (cpu_has_tsc)
apic_printk(APIC_VERBOSE, "..... CPU clock speed is "
"%ld.%04ld MHz.\n",
((long)(t2-t1)/LOOPS)/(1000000/HZ),
((long)(t2-t1)/LOOPS)%(1000000/HZ));
apic_printk(APIC_VERBOSE, "..... host bus clock speed is "
"%ld.%04ld MHz.\n",
result/(1000000/HZ),
result%(1000000/HZ));
/* set up multipliers for accurate timer code */
bus_freq = result*HZ;
bus_cycle = (u32) (1000000000000LL/bus_freq); /* in pico seconds */
bus_scale = (1000*262144)/bus_cycle;
apic_printk(APIC_VERBOSE, "..... bus_scale = 0x%08X\n", bus_scale);
/* reset APIC to zero timeout value */
__setup_APIC_LVTT(0);
return result;
}
