ref: 909323e92a4e694bff5908e500d8655ac1bbd932
dir: /sys/src/9/kw/clock.c/
/* * kirkwood clocks * * timers count down to zero. */ #include "u.h" #include "../port/lib.h" #include "mem.h" #include "dat.h" #include "fns.h" #include "io.h" #include "ureg.h" enum { Tcycles = CLOCKFREQ / HZ, /* cycles per clock tick */ Dogperiod = 15 * CLOCKFREQ, /* at most 21 s.; must fit in ulong */ MaxPeriod = Tcycles, MinPeriod = MaxPeriod / 100, /* timer ctl bits */ Tmr0enable = 1<<0, Tmr0reload = 1<<1, /* at 0 count, load timer0 from reload0 */ Tmr1enable = 1<<2, Tmr1reload = 1<<3, /* at 0 count, load timer1 from reload1 */ TmrWDenable = 1<<4, TmrWDreload = 1<<5, }; typedef struct TimerReg TimerReg; struct TimerReg { ulong ctl; ulong pad[3]; ulong reload0; ulong timer0; /* cycles until zero */ ulong reload1; ulong timer1; /* cycles until zero */ ulong reloadwd; ulong timerwd; }; static int ticks; /* for sanity checking; m->ticks doesn't always get updated */ static void clockintr(Ureg *ureg, void *arg) { TimerReg *tmr = arg; static int nesting; tmr->timerwd = Dogperiod; /* reassure the watchdog */ ticks++; coherence(); if (nesting == 0) { /* if the clock interrupted itself, bail out */ ++nesting; timerintr(ureg, 0); --nesting; } intrclear(Irqbridge, IRQcputimer0); } /* stop clock interrupts and disable the watchdog timer */ void clockshutdown(void) { TimerReg *tmr = (TimerReg *)soc.clock; tmr->ctl = 0; coherence(); } void clockinit(void) { int i, s; CpucsReg *cpu = (CpucsReg *)soc.cpu; TimerReg *tmr = (TimerReg *)soc.clock; clockshutdown(); /* * verify sanity of timer0 */ intrenable(Irqbridge, IRQcputimer0, clockintr, tmr, "clock0"); s = spllo(); /* risky */ /* take any deferred clock (& other) interrupts here */ splx(s); /* adjust m->bootdelay, used by delay()? */ m->ticks = ticks = 0; m->fastclock = 0; tmr->timer0 = 1; tmr->ctl = Tmr0enable; /* just once */ coherence(); s = spllo(); /* risky */ for (i = 0; i < 10 && ticks == 0; i++) { delay(1); coherence(); } splx(s); if (ticks == 0) { serialputc('?'); if (tmr->timer0 == 0) panic("clock not interrupting"); else if (tmr->timer0 == tmr->reload0) panic("clock not ticking"); else panic("clock running very slowly"); } /* * configure all timers */ clockshutdown(); tmr->reload0 = tmr->timer0 = Tcycles; /* tick clock */ tmr->reload1 = tmr->timer1 = ~0; /* cycle clock */ tmr->timerwd = Dogperiod; /* watch dog timer */ coherence(); tmr->ctl = Tmr0enable | Tmr0reload | Tmr1enable | Tmr1reload | TmrWDenable; cpu->rstout |= RstoutWatchdog; coherence(); } void timerset(Tval next) { int offset; TimerReg *tmr = (TimerReg *)soc.clock; offset = next - fastticks(nil); if(offset < MinPeriod) offset = MinPeriod; else if(offset > MaxPeriod) offset = MaxPeriod; tmr->timer0 = offset; coherence(); } uvlong fastticks(uvlong *hz) { uvlong now; int s; if(hz) *hz = CLOCKFREQ; s = splhi(); /* zero low ulong of fastclock */ now = (m->fastclock & ~(uvlong)~0ul) | perfticks(); if(now < m->fastclock) /* low bits must have wrapped */ now += 1ll << 32; m->fastclock = now; splx(s); return now; } ulong perfticks(void) { TimerReg *tmr = (TimerReg *)soc.clock; return ~tmr->timer1; } long lcycles(void) { return perfticks(); } ulong µs(void) { return fastticks2us(fastticks(nil)); } void microdelay(int l) { int i; l *= m->delayloop; l /= 1000; if(l <= 0) l = 1; for(i = 0; i < l; i++) ; } void delay(int l) { ulong i, j; j = m->delayloop; while(l-- > 0) for(i=0; i < j; i++) ; }