diff options
| author | Miod Vallat <miod@cvs.openbsd.org> | 2004-08-25 08:01:41 +0000 |
|---|---|---|
| committer | Miod Vallat <miod@cvs.openbsd.org> | 2004-08-25 08:01:41 +0000 |
| commit | 7017776279a1ec23838da5575e8312b270237930 (patch) | |
| tree | dee3327e024246d8d3c3fec16b93f894ec4413d0 /sys | |
| parent | 1462321a7eb4afd69017e16f256fdcdef72de02f (diff) | |
Better DUART timer interval computation for clock.
Diffstat (limited to 'sys')
| -rw-r--r-- | sys/arch/mvme88k/dev/clock.c | 32 |
1 files changed, 12 insertions, 20 deletions
diff --git a/sys/arch/mvme88k/dev/clock.c b/sys/arch/mvme88k/dev/clock.c index 98a4bd98dbb..f8c7f0edb55 100644 --- a/sys/arch/mvme88k/dev/clock.c +++ b/sys/arch/mvme88k/dev/clock.c @@ -1,4 +1,4 @@ -/* $OpenBSD: clock.c,v 1.39 2004/08/25 08:00:06 miod Exp $ */ +/* $OpenBSD: clock.c,v 1.40 2004/08/25 08:01:40 miod Exp $ */ /* * Copyright (c) 1999 Steve Murphree, Jr. * Copyright (c) 1995 Theo de Raadt @@ -109,7 +109,6 @@ void sbc_initclock(void); void sbc_initstatclock(void); void m188_initclock(void); void m188_initstatclock(void); -void m188_timer_init(unsigned); void m188_cio_init(unsigned); u_int read_cio(int); void write_cio(int, u_int); @@ -372,6 +371,9 @@ m188_clockintr(void *eframe) void m188_initclock(void) { + volatile int imr; + int counter; + #ifdef CLOCK_DEBUG printf("VME188 clock init\n"); #endif @@ -380,25 +382,15 @@ m188_initclock(void) hz = 100; } tick = 1000000 / hz; - m188_timer_init(tick); -} -void -m188_timer_init(unsigned period) -{ - volatile int imr; - int counter; + /* + * The DUART runs at 3.6864 MHz in PCLK/16 mode, hence for a + * 100 Hz timer, it needs (3686400 / 16) / 100 ticks per cycle. + */ + counter = (3686400 / 16) / hz; - /* make sure the counter range is proper. */ - if (period < 9) - counter = 2; - else if (period > 284421) - counter = 65535; - else - counter = period / 4.34; #ifdef CLOCK_DEBUG - printf("tick == %d, period == %d\n", tick, period); - printf("timer will interrupt every %d usec\n", (int) (counter * 4.34)); + printf("tick == %d, counter == %d\n", tick, counter); #endif /* clear the counter/timer output OP3 while we program the DART */ *((int *volatile)DART_OPCR) = 0x00; @@ -409,8 +401,8 @@ m188_timer_init(unsigned period) /* set counter/timer to counter mode, clock/16 */ *((int *volatile)DART_ACR) = 0x30; - *((int *volatile)DART_CTUR) = counter / 256; /* set counter MSB */ - *((int *volatile)DART_CTLR) = counter % 256; /* set counter LSB */ + *((int *volatile)DART_CTUR) = (counter >> 8); + *((int *volatile)DART_CTLR) = (counter & 0xff); /* set interrupt vec */ *((int *volatile)DART_IVR) = SYSCON_VECT + SYSCV_TIMER1; |