108 lines
3.3 KiB
C
108 lines
3.3 KiB
C
/* $NetBSD: clock.c,v 1.3 1998/01/19 11:39:59 drochner Exp $ */
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/*
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* Copyright (C) 1995, 1996 Wolfgang Solfrank.
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* Copyright (C) 1995, 1996 TooLs GmbH.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by TooLs GmbH.
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* 4. The name of TooLs GmbH may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/param.h>
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#include <dev/isa/isareg.h>
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#include <dev/ic/i8253reg.h>
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#define FIRST_GUESS 0x2000
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static u_long ns_per_tick;
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static inline u_quad_t
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mftb()
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{
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u_long scratch;
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u_quad_t tb;
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asm ("1: mftbu %0; mftb %0+1; mftbu %1; cmpw %0,%1; bne 1b"
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: "=r"(tb), "=r"(scratch));
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return tb;
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}
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/*
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* Wait for about n microseconds (at least!).
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*/
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void
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delay(n)
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int n;
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{
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u_quad_t tb;
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u_long tbh, tbl, scratch;
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tb = mftb();
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tb += (n * 1000 + ns_per_tick - 1) / ns_per_tick;
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tbh = tb >> 32;
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tbl = tb;
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asm ("1: mftbu %0; cmpw %0,%1; blt 1b; bgt 2f; mftb %0; cmpw %0,%2; blt 1b; 2:"
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:: "r"(scratch), "r"(tbh), "r"(tbl));
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}
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int
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findcpuspeed()
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{
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int i;
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int ticks_per_sec;
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u_short remainder;
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u_quad_t tstart, tend;
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/* Put counter in count down mode */
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outb(IO_TIMER1 + TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN);
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outb(IO_TIMER1 + TIMER_CNTR0, 0xff); /* lo */
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outb(IO_TIMER1 + TIMER_CNTR0, 0xff); /* hi */
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for (i = FIRST_GUESS; i; i--)
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;
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/* Read the value left in the counter */
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outb(IO_TIMER1 + TIMER_MODE, TIMER_SEL0|TIMER_LATCH);
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remainder = inb(IO_TIMER1 + TIMER_CNTR0);
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remainder += (inb(IO_TIMER1 + TIMER_CNTR0) << 8);
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tstart = mftb();
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for (i = FIRST_GUESS; i; i--)
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;
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tend = mftb();
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if (tend > tstart)
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tend -= tstart;
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else
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tend += UQUAD_MAX - tstart;
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ticks_per_sec = (int)(tend * TIMER_FREQ / (0xffff - remainder));
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if (ticks_per_sec > 8000000) /* XXX */
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ticks_per_sec = 33000000 / 4;
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else
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ticks_per_sec = 25000000 / 4;
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ns_per_tick = 1000000000 / ticks_per_sec;
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return (ticks_per_sec);
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}
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