1 /* $NetBSD: clock.c,v 1.2 2001/11/17 18:55:57 kleink Exp $ */ 2 3 /* 4 * Copyright (C) 1995, 1996 Wolfgang Solfrank. 5 * Copyright (C) 1995, 1996 TooLs GmbH. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by TooLs GmbH. 19 * 4. The name of TooLs GmbH may not be used to endorse or promote products 20 * derived from this software without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 26 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 27 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 28 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 29 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 30 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 31 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 #include <lib/libsa/stand.h> 35 #include <dev/isa/isareg.h> 36 #include <dev/ic/i8253reg.h> 37 38 #include "boot.h" 39 40 u_long ns_per_tick = NS_PER_TICK; 41 42 static inline u_quad_t mftb __P((void)); 43 44 static inline u_quad_t 45 mftb() 46 { 47 u_long scratch; 48 u_quad_t tb; 49 50 asm ("1: mftbu %0; mftb %0+1; mftbu %1; cmpw %0,%1; bne 1b" 51 : "=r"(tb), "=r"(scratch)); 52 return (tb); 53 } 54 55 /* 56 * Wait for about n microseconds (at least!). 57 */ 58 void 59 delay(n) 60 u_int n; 61 { 62 u_quad_t tb; 63 u_long tbh, tbl, scratch; 64 65 tb = mftb(); 66 tb += (n * 1000 + ns_per_tick - 1) / ns_per_tick; 67 tbh = tb >> 32; 68 tbl = tb; 69 asm ("1: mftbu %0; cmpw %0,%1; blt 1b; bgt 2f; mftb %0; cmpw 0, %0,%2; blt 1b; 2:" 70 : "=r"(scratch) : "r"(tbh), "r"(tbl)); 71 } 72