Timecounter support for acorn26, using IOC timer 0 and a bit of trickery.
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bjh21
parent
aaaf91526d
commit
578a81db96
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@ -1,4 +1,4 @@
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/* $NetBSD: types.h,v 1.7 2006/09/03 11:51:29 bjh21 Exp $ */
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/* $NetBSD: types.h,v 1.8 2006/10/04 23:40:00 bjh21 Exp $ */
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#ifndef _ACORN26_TYPES_H_
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#define _ACORN26_TYPES_H_
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@ -8,5 +8,6 @@
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#define __HAVE_GENERIC_SOFT_INTERRUPTS
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#define __GENERIC_SOFT_INTERRUPTS_ALL_LEVELS
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#define __HAVE_GENERIC_TODR
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#define __HAVE_TIMECOUNTER
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#endif /* _ACORN26_TYPES_H_ */
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@ -1,4 +1,4 @@
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/* $NetBSD: ioc.c,v 1.14 2006/10/04 20:29:51 bjh21 Exp $ */
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/* $NetBSD: ioc.c,v 1.15 2006/10/04 23:40:00 bjh21 Exp $ */
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/*-
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* Copyright (c) 1998, 1999, 2000 Ben Harris
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@ -31,7 +31,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: ioc.c,v 1.14 2006/10/04 20:29:51 bjh21 Exp $");
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__KERNEL_RCSID(0, "$NetBSD: ioc.c,v 1.15 2006/10/04 23:40:00 bjh21 Exp $");
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#include <sys/param.h>
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#include <sys/device.h>
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@ -39,6 +39,7 @@ __KERNEL_RCSID(0, "$NetBSD: ioc.c,v 1.14 2006/10/04 20:29:51 bjh21 Exp $");
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#include <sys/queue.h>
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#include <sys/reboot.h> /* For bootverbose */
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#include <sys/systm.h>
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#include <sys/timetc.h>
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#include <machine/bus.h>
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#include <machine/intr.h>
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@ -58,6 +59,7 @@ static int ioc_search(struct device *parent, struct cfdata *cf,
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static int ioc_print(void *aux, const char *pnp);
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static int ioc_irq_clock(void *cookie);
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static int ioc_irq_statclock(void *cookie);
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static u_int ioc_get_timecount(struct timecounter *);
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CFATTACH_DECL(ioc, sizeof(struct ioc_softc),
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ioc_match, ioc_attach, NULL, NULL);
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@ -333,6 +335,13 @@ cpu_initclocks(void)
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sc->sc_dev.dv_xname, "clock");
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sc->sc_clkirq = irq_establish(IOC_IRQ_TM0, IPL_CLOCK, ioc_irq_clock,
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NULL, &sc->sc_clkev);
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sc->sc_tc.tc_get_timecount = ioc_get_timecount;
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sc->sc_tc.tc_counter_mask = ~(u_int)0;
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sc->sc_tc.tc_frequency = IOC_TIMER_RATE;
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sc->sc_tc.tc_name = sc->sc_dev.dv_xname;
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sc->sc_tc.tc_quality = 100;
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sc->sc_tc.tc_priv = sc;
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tc_init(&sc->sc_tc);
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if (bootverbose)
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printf("%s: %d Hz clock interrupting at %s\n",
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the_ioc->dv_xname, hz, irq_string(sc->sc_clkirq));
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@ -365,7 +374,9 @@ cpu_initclocks(void)
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static int
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ioc_irq_clock(void *cookie)
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{
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struct ioc_softc *sc = (void *)the_ioc;
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sc->sc_tcbase += t0_count + 1;
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hardclock(cookie);
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return IRQ_HANDLED;
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}
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@ -403,82 +414,40 @@ setstatclockrate(int hzrate)
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KASSERT(hzrate == stathz);
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}
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void
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microtime(struct timeval *tvp)
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/*
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* IOC timecounter
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*
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* We construct a timecounter from timer 0, which is also running the
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* hardclock interrupt. Since the timer 0 resets on every hardclock
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* interrupt, we keep track of the high-order bits of the counter in
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* software, incrementing it on every hardclock. If hardclock
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* interrupts are disabled, there's a period where the timer has reset
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* but the interrupt handler hasn't incremented the hight-order bits.
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* We detect this by checking whether there's a hardclock interrupt
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* pending. We take a bit of extra care to ensure that we aren't
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* confused by the interrupt happening between our latching the
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* timer's count and reading the interrupt flag.
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*/
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static u_int
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ioc_get_timecount(struct timecounter *tc)
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{
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static struct timeval lasttime;
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struct timeval t;
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struct device *self;
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struct ioc_softc *sc;
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bus_space_tag_t bst;
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bus_space_handle_t bsh;
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long sec, usec;
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int t0, s, intbefore, intafter;
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KASSERT(the_ioc != NULL);
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self = the_ioc;
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sc = (struct ioc_softc *)self;
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bst = sc->sc_bst;
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bsh = sc->sc_bsh;
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struct ioc_softc *sc = tc->tc_priv;
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bus_space_tag_t bst = sc->sc_bst;
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bus_space_handle_t bsh = sc->sc_bsh;
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u_int t0, count;
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int s, intpending;
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s = splclock();
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t = time;
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intbefore = ioc_irq_status(IOC_IRQ_TM0);
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bus_space_write_1(bst, bsh, IOC_T0LATCH, 0);
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if (__predict_false((intpending = ioc_irq_status(IOC_IRQ_TM0))))
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bus_space_write_1(bst, bsh, IOC_T0LATCH, 0);
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t0 = bus_space_read_1(bst, bsh, IOC_T0LOW);
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t0 += bus_space_read_1(bst, bsh, IOC_T0HIGH) << 8;
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intafter = ioc_irq_status(IOC_IRQ_TM0);
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count = sc->sc_tcbase - t0;
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if (intpending)
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count += t0_count + 1;
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splx(s);
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/*
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* If there's a timer interrupt pending, the counter has
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* probably wrapped around once since "time" was last updated.
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* Things are complicated by the fact that this could happen
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* while we're trying to work out the time. We include some
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* heuristics to spot this.
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*
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* NB: t0 counts down from t0_count to 0.
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*/
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if (intbefore || (intafter && t0 < t0_count / 2))
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t0 -= t0_count;
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t.tv_usec += (t0_count - t0) / (IOC_TIMER_RATE / 1000000);
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while (t.tv_usec > 1000000) {
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t.tv_usec -= 1000000;
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t.tv_sec++;
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}
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/*
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* Ordinarily, the current clock time is guaranteed to be later
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* by at least one microsecond than the last time the clock was
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* read. However, this rule applies only if the current time is
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* within one second of the last time. Otherwise, the clock will
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* (shudder) be set backward. The clock adjustment daemon or
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* human equivalent is presumed to be correctly implemented and
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* to set the clock backward only upon unavoidable crisis.
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*/
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sec = lasttime.tv_sec - t.tv_sec;
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usec = lasttime.tv_usec - t.tv_usec;
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if (usec < 0) {
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usec += 1000000;
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sec--;
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}
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if (sec == 0) {
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t.tv_usec += usec + 1;
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if (t.tv_usec >= 1000000) {
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t.tv_usec -= 1000000;
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t.tv_sec++;
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}
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}
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lasttime = t;
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*tvp = t;
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return count;
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}
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void
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@ -1,4 +1,4 @@
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/* $NetBSD: iocvar.h,v 1.3 2006/09/30 15:14:21 bjh21 Exp $ */
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/* $NetBSD: iocvar.h,v 1.4 2006/10/04 23:40:00 bjh21 Exp $ */
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/*-
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* Copyright (c) 1998, 1999 Ben Harris
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* All rights reserved.
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@ -32,6 +32,7 @@
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#ifndef _ARM26_IOCVAR_H
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#define _ARM26_IOCVAR_H
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#include <sys/timetc.h>
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#include <machine/irq.h>
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/* Structure passed to children of an IOC */
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@ -58,6 +59,8 @@ struct ioc_softc {
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struct evcnt sc_clkev;
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struct irq_handler *sc_sclkirq;
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struct evcnt sc_sclkev;
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struct timecounter sc_tc;
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u_int sc_tcbase;
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u_int8_t sc_ctl;
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};
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