Allow DELAY() to be called anytime:
-don't enable interrupts at the end of gettick(), restore the previous state instead -start timer/counter 0 from delay() if necessary -comment out "findcpuspeed()", it would clobber the timer again, and it is unused anyway
This commit is contained in:
drochner
parent
3f38ea4063
commit
ac884fce95
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@ -1,4 +1,4 @@
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/* $NetBSD: clock.c,v 1.44 1997/02/13 00:59:15 jonathan Exp $ */
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/* $NetBSD: clock.c,v 1.45 1998/02/05 19:59:54 drochner Exp $ */
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/*-
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* Copyright (c) 1993, 1994 Charles Hannum.
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@ -106,8 +106,11 @@ WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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#include <i386/isa/timerreg.h>
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#include <i386/isa/spkrreg.h>
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static void initrtclock __P((void));
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void spinwait __P((int));
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#if 0
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void findcpuspeed __P((void));
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#endif
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int clockintr __P((void *));
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int gettick __P((void));
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void sysbeepstop __P((void *));
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@ -148,6 +151,32 @@ mc146818_write(sc, reg, datum)
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outb(IO_RTC+1, datum);
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}
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static u_long rtclock_tval;
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/* minimal initialization, enough for delay() */
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static void
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initrtclock()
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{
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u_long tval;
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/*
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* Compute timer_count, the count-down count the timer will be
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* set to. Also, correctly round
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* this by carrying an extra bit through the division.
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*/
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tval = (TIMER_FREQ * 2) / (u_long) hz;
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tval = (tval / 2) + (tval & 0x1);
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/* initialize 8253 clock */
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outb(TIMER_MODE, TIMER_SEL0|TIMER_RATEGEN|TIMER_16BIT);
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/* Correct rounding will buy us a better precision in timekeeping */
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outb(IO_TIMER1, tval % 256);
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outb(IO_TIMER1, tval / 256);
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rtclock_tval = tval;
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}
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/*
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* microtime() makes use of the following globals. Note that isa_timer_tick
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* may be redundant to the `tick' variable, but is kept here for stability.
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@ -171,8 +200,12 @@ startrtclock()
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u_long tval;
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u_long t, msb, lsb, quotient, remainder;
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#if 0
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findcpuspeed(); /* use the clock (while it's free)
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to find the cpu speed */
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#endif
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if (!rtclock_tval)
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initrtclock();
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/*
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* Compute timer_tick from hz. We truncate this value (i.e.
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@ -182,13 +215,10 @@ startrtclock()
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isa_timer_tick = 1000000 / (u_long) hz;
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/*
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* Compute timer_count, the count-down count the timer will be
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* set to. We can't stand any number with an MSB larger than
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* TIMER_MSB_TABLE_SIZE will accomodate. Also, correctly round
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* this by carrying an extra bit through the division.
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* We can't stand any number with an MSB larger than
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* TIMER_MSB_TABLE_SIZE will accomodate.
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*/
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tval = (TIMER_FREQ * 2) / (u_long) hz;
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tval = (tval / 2) + (tval & 0x1);
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tval = rtclock_tval;
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if ((tval / 256) >= ISA_TIMER_MSB_TABLE_SIZE
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|| TIMER_FREQ > (8*1024*1024)) {
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panic("startrtclock: TIMER_FREQ/HZ unsupportable");
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@ -243,13 +273,6 @@ startrtclock()
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}
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}
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/* initialize 8253 clock */
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outb(TIMER_MODE, TIMER_SEL0|TIMER_RATEGEN|TIMER_16BIT);
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/* Correct rounding will buy us a better precision in timekeeping */
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outb(IO_TIMER1, isa_timer_count % 256);
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outb(IO_TIMER1, isa_timer_count / 256);
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/* Check diagnostic status */
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if ((s = mc146818_read(NULL, NVRAM_DIAG)) != 0) { /* XXX softc */
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char bits[128];
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@ -271,15 +294,17 @@ clockintr(arg)
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int
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gettick()
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{
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u_long ef;
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u_char lo, hi;
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/* Don't want someone screwing with the counter while we're here. */
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ef = read_eflags();
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disable_intr();
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/* Select counter 0 and latch it. */
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outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
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lo = inb(TIMER_CNTR0);
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hi = inb(TIMER_CNTR0);
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enable_intr();
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write_eflags(ef);
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return ((hi << 8) | lo);
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}
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@ -296,6 +321,10 @@ delay(n)
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{
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int limit, tick, otick;
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/* allow DELAY() to be used before startrtclock() */
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if (!rtclock_tval)
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initrtclock();
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/*
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* Read the counter first, so that the rest of the setup overhead is
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* counted.
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@ -387,6 +416,7 @@ sysbeep(pitch, period)
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timeout(sysbeepstop, 0, period);
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}
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#if 0
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unsigned int delaycount; /* calibrated loop variable (1 millisecond) */
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#define FIRST_GUESS 0x2000
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@ -411,6 +441,7 @@ findcpuspeed()
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*/
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delaycount = (FIRST_GUESS * TIMER_DIV(1000)) / (0xffff-remainder);
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}
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#endif
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void
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cpu_initclocks()
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