2002/0410/pc/i8253.c (diff list | history)

2002/0409/sys/src/9/pc/i8253.c:46,56 – 2002/0410/sys/src/9/pc/i8253.c:46,51 (short | long | prev | next)
2000/0623		Trigger=0x0, /* interrupt on terminal count */ Sstrobe=0x8, /* software triggered strobe */
1997/0327
2000/0623		/* counter 2 controls */ C2gate= 0x1, C2speak=0x2, C2out= 0x10,
2002/0409		/* T2ctl bits */ T2gate= (1<<0), /* enable T2 counting */ T2spkr= (1<<1), /* connect T2 out to speaker */
2002/0409/sys/src/9/pc/i8253.c:57,83 – 2002/0410/sys/src/9/pc/i8253.c:52,74
2002/0409		T2out= (1<<5), /* output of T2 */
1997/0327		Freq= 1193182, /* Real clock frequency */
2002/0409		Tickshift= 8, /* increase tick wriggle room */
2000/0623
2000/0706		Minusec=20, /* minimum cycles for a clock interrupt */
2000/0623		FreqMul=16, /* extra accuracy in fastticks/Freq calculation; ok up to ~8ghz */
2002/0410		Tickshift=8, /* extra accuracy */ MaxPeriod=Freq/HZ, MinPeriod=Freq/(100*HZ),
1997/0327		};
2000/0623		static struct {
2000/0627		Lock;
2002/0410		ulong period; /* current clock period */
2000/0701		int enabled;
2000/0627		int mode;
2000/0623		vlong when; /* next fastticks a clock interrupt should occur */
2002/0405		vlong timerwhen; /* next fastticks a cycintr happens; 0 == infinity */
2000/0623		long fastperiod; /* fastticks/hz */ long fast2freq; /* fastticks*FreqMul/Freq */
2002/0410		uvlong hz;
2002/0405
2002/0409		ushort last; /* last value of clock 1 */ uvlong ticks; /* cumulative ticks of counter 1 */
2000/0623		}i8253;
2000/0622
2002/0410
1997/0327		void
2002/0405		i8253init(void)
1997/0327		{
2002/0409/sys/src/9/pc/i8253.c:87,98 – 2002/0410/sys/src/9/pc/i8253.c:78,89
2002/0405		ioalloc(T2ctl, 1, 0, "i8253.cntr2ctl");
2000/0623
2002/0405		/* * set interrupting clock for 1/HZ seconds
2002/0410		* enable a 1/HZ interrupt for providing scheduling interrupts
2002/0405		*/ outb(Tmode, Load0|Square); i8253.mode = Square; outb(T0cntr, (Freq/HZ)); /* low byte */ outb(T0cntr, (Freq/HZ)>>8); /* high byte */
2002/0410		i8253.period = Freq/HZ;
1998/0903
2002/0405		/*
2002/0409		* enable a longer period counter to use as a clock
2002/0409/sys/src/9/pc/i8253.c:100,109 – 2002/0410/sys/src/9/pc/i8253.c:91,101
2002/0409		outb(Tmode, Load2|Square); outb(T2cntr, 0); /* low byte */ outb(T2cntr, 0); /* high byte */
2002/0410		i8253.period = Freq/HZ;
2002/0409		x = inb(T2ctl); x |= T2gate; outb(T2ctl, x);
2002/0405
2002/0410
2002/0405		/* * Introduce a little delay to make sure the count is * latched and the timer is counting down; with a fast
2002/0409/sys/src/9/pc/i8253.c:189,285 – 2002/0410/sys/src/9/pc/i8253.c:181,238
1999/0131		m->cpumhz = (cpufreq + cpufreq/200)/1000000; m->cpuhz = cpufreq; }
2002/0410		i8253.hz = Freq<<Tickshift;
1997/0327		}
2000/0627		/* * schedule the next interrupt
2002/0405		* timerwhen is the time of the next interrupt
2000/0627		*/
2000/0621		static void
2000/0627		clockintrsched0(vlong next)
2002/0410		ulong i8253periodset; void i8253timerset(uvlong next)
2000/0621		{
2000/0623		vlong now; long set;
2002/0410		ulong period; ulong want; ulong now;
2000/0623
2002/0405		i8253.timerwhen = next;
2000/0627		if(i8253.mode == Square && next == 0) return;
2002/0410		want = next>>Tickshift; now = i8253.ticks; /* assuming whomever called us just did fastticks() */
2000/0627
2000/0623		now = fastticks(nil);
2000/0627		if(next || now < i8253.when - i8253.fastperiod || now > i8253.when - ((3*i8253.fastperiod)>>2)){ if(next > i8253.when) next = i8253.when; set = (long)(next - now) * FreqMul / i8253.fast2freq; set -= 3; /* three cycles for the count to take effect: outb, outb, wait */ if(i8253.mode != Trigger){ outb(Tmode, Load0|Trigger); i8253.mode = Trigger; set--; }
2000/0706		if(set < Minusec) set = Minusec;
2000/0627		outb(T0cntr, set); /* low byte */ outb(T0cntr, set>>8); /* high byte */ }else if(i8253.mode != Square){ i8253.mode = Square; outb(Tmode, Load0|Square); outb(T0cntr, (Freq/HZ)); /* low byte */ outb(T0cntr, (Freq/HZ)>>8); /* high byte */
2002/0410		period = MaxPeriod; if(next != 0){ period = want - now; if(period < MinPeriod) period = MinPeriod; else if(period > (4*MaxPeriod)/5) /* strong attraction to MaxPeriod */ period = MaxPeriod;
2000/0627		} }
2000/0623
2000/0701		int
2002/0405		havetimer(void)
2000/0701		{
2002/0405		return i8253.enabled;
2000/0701		}
2002/0410		/* histeresis */ if(i8253.period != period){ ilock(&i8253); /* load new value */ outb(Tmode, Load0|Square); outb(T0cntr, period); /* low byte */ outb(T0cntr, period>>8); /* high byte */
2000/0701
2000/0627		void clockintrsched(void) { vlong next;                  ilock(&i8253);
2002/0405		if(i8253.enabled){ next = timernext(); if(next != i8253.timerwhen)
2000/0701		clockintrsched0(next);
2002/0410		/* remember period */ i8253.period = period; i8253periodset++; iunlock(&i8253);
2000/0701		}
2000/0627		iunlock(&i8253); } static void clockintr0(Ureg* ureg, void *v)
2002/0410		i8253clock(Ureg* ureg, void*)
2000/0627		{ vlong now, when;
2000/0713
2002/0405		/* goes with syncing in squidboy */ if(m->havetsc) rdtsc(&m->lasttsc);
2000/0627		now = fastticks(nil); when = i8253.when;
2002/0406
2000/0627		if(now >= i8253.when){ clockintr(ureg, v); do i8253.when += i8253.fastperiod; while(i8253.when < now); }
2002/0405		if(i8253.timerwhen || i8253.mode != Square) clockintrsched0(checktimer(ureg, v));
2002/0410		timerintr(ureg, 0);
2000/0621		}
1997/0327		void i8253enable(void) {
2002/0405		uvlong hz;                  i8253.when = fastticks(&hz); i8253.fastperiod = (hz + HZ/2) / HZ; i8253.fast2freq = (hz * FreqMul) / Freq;
2000/0701		i8253.enabled = 1;
2000/0621		intrenable(IrqCLOCK, clockintr0, 0, BUSUNKNOWN, "clock");
2002/0410		i8253.period = Freq/HZ; intrenable(IrqCLOCK, i8253clock, 0, BUSUNKNOWN, "clock");
1997/0327		}
1998/0710		/*
2002/0409/sys/src/9/pc/i8253.c:294,300 – 2002/0410/sys/src/9/pc/i8253.c:247,253
2002/0405		uvlong ticks;
1998/0710		if(hz)
2002/0409		*hz = Freq<<Tickshift;
2002/0410		*hz = i8253.hz;
2002/0405
2002/0409		ilock(&i8253); outb(Tmode, Latch2);
2002/0409/sys/src/9/pc/i8253.c:304,310 – 2002/0410/sys/src/9/pc/i8253.c:257,263
2002/0409		if(y < i8253.last) x = i8253.last - y;
2002/0405		else
2002/0409		x = i8253.last + (0x1000 - y);
2002/0410		x = i8253.last + (0x10000 - y);
2002/0409		i8253.last = y; i8253.ticks += x>>1; ticks = i8253.ticks;
2002/0409/sys/src/9/pc/i8253.c:313,323 – 2002/0410/sys/src/9/pc/i8253.c:266,299
2002/0409		return ticks<<Tickshift;
2002/0405		} /* * return value and speed of timer set in arch->clockenable */ vlong fastticks(uvlong *hz)
2002/0410		void delay(int millisecs)
2002/0405		{ return (*arch->fastclock)(hz);
2002/0410		millisecs *= m->loopconst; if(millisecs <= 0) millisecs = 1; aamloop(millisecs); } void microdelay(int microsecs) { microsecs *= m->loopconst; microsecs /= 1000; if(microsecs <= 0) microsecs = 1; aamloop(microsecs); } ulong TK2MS(ulong ticks) { uvlong t, hz; t = ticks; hz = HZ; t *= 1000L; t = t/hz; ticks = t; return ticks;
1998/0710		}