xref: /inferno-os/os/mpc/clock.c (revision 74a4d8c26dd3c1e9febcb717cfd6cb6512991a7a)

#include	"u.h"
#include	"../port/lib.h"
#include	"mem.h"
#include	"dat.h"
#include	"fns.h"
#include	"io.h"
#include	"ureg.h"

#include	<isa.h>
#include	<interp.h>

typedef struct Clock0link Clock0link;
typedef struct Clock0link {
	void		(*clock)(void);
	Clock0link*	link;
} Clock0link;

static Clock0link *clock0link;
static Lock clock0lock;
ulong	clkrelinq;
void	(*kproftick)(ulong);	/* set by devkprof.c when active */
void	(*archclocktick)(void);	/* set by arch*.c when desired */

Timer*
addclock0link(void (*clock)(void), int)
{
	Clock0link *lp;

	if((lp = malloc(sizeof(Clock0link))) == 0){
		print("addclock0link: too many links\n");
		return nil;
	}
	ilock(&clock0lock);
	lp->clock = clock;
	lp->link = clock0link;
	clock0link = lp;
	iunlock(&clock0lock);
	return nil;
}

void
delay(int l)
{
	ulong i, j;

	j = m->delayloop;
	while(l-- > 0)
		for(i=0; i < j; i++)
			;
}

void
microdelay(int l)
{
	ulong i;

	l *= m->delayloop;
	l /= 1000;
	if(l <= 0)
		l = 1;
	for(i = 0; i < l; i++)
		;
}

enum {
	Timebase = 4,	/* system clock cycles per time base cycle */
};

static	ulong	clkreload;

void
clockinit(void)
{
	long x;

	m->delayloop = m->cpuhz/1000;	/* initial estimate */
	do {
		x = gettbl();
		delay(10);
		x = gettbl() - x;
	} while(x < 0);

	/*
	 *  fix count
	 */
	m->delayloop = ((vlong)m->delayloop*(10*m->clockgen/1000))/(x*Timebase);
	if(m->delayloop == 0)
		m->delayloop = 1;

	clkreload = (m->clockgen/Timebase)/HZ-1;
	putdec(clkreload);
}

void
clockintr(Ureg *ur)
{
	Clock0link *lp;
	long v;

	v = -getdec();
	if(v > clkreload/2){
		if(v > clkreload)
			m->ticks += v/clkreload;
		v = 0;
	}
	putdec(clkreload-v);

	/* watchdog */
	if(m->iomem->sypcr & (1<<2)){
		m->iomem->swsr = 0x556c;
		m->iomem->swsr = 0xaa39;
	}

	m->ticks++;
	if(archclocktick != nil)
		archclocktick();

	if(up)
		up->pc = ur->pc;

	checkalarms();
	if(m->machno == 0) {
		if(kproftick != nil)
			(*kproftick)(ur->pc);
		if(canlock(&clock0lock)){
			for(lp = clock0link; lp; lp = lp->link)
				lp->clock();
			unlock(&clock0lock);
		}
	}

	if(up && up->state == Running){
		if(cflag && up->type == Interp && tready(nil))
			ur->cr |= 1;	/* set flag in condition register for ../../libinterp/comp-power.c:/^schedcheck */
	}
	/* other preemption checks are done by trap.c */
}

uvlong
fastticks(uvlong *hz)
{
	if(hz)
		*hz = HZ;
	return m->ticks;
}