sys/arch/prep/stand/boot/clock.c

   1 /*      $NetBSD: clock.c,v 1.8 2005/12/24 23:24:02 perry 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 #include <powerpc/spr.h>
  38
  39 #include "boot.h"
  40
  41 u_long ns_per_tick = NS_PER_TICK;
  42
  43 static inline u_quad_t mftb(void);
  44 static inline void mfrtc(u_long *, u_long *);
  45
  46 static inline u_quad_t
  47 mftb(void)
  48 {
  49         u_long scratch;
  50         u_quad_t tb;
  51
  52         __asm volatile ("1: mftbu %0; mftb %0+1; mftbu %1; cmpw %0,%1; bne 1b"
  53             : "=r"(tb), "=r"(scratch));
  54         return (tb);
  55 }
  56
  57 static inline void
  58 mfrtc(u_long *up, u_long *lp)
  59 {
  60         u_long scratch;
  61
  62         __asm volatile ("1: mfspr %0,%3; mfspr %1,%4; mfspr %2,%3;"
  63             "cmpw %0,%2; bne 1b"
  64             : "=r"(*up), "=r"(*lp), "=r"(scratch)
  65             : "n"(SPR_RTCU_R), "n"(SPR_RTCL_R));
  66 }
  67
  68 /*
  69  * Wait for about n microseconds (at least!).
  70  */
  71 void
  72 delay(u_int n)
  73 {
  74         u_quad_t tb;
  75         u_long tbh, tbl, scratch;
  76         unsigned int cpuvers;
  77
  78         __asm volatile ("mfpvr %0" : "=r"(cpuvers));
  79         cpuvers >>= 16;
  80
  81         if (cpuvers == MPC601) {
  82                 mfrtc(&tbh, &tbl);
  83                 while (n >= 1000000) {
  84                         tbh++;
  85                         n -= 1000000;
  86                 }
  87                 tbl += n * 1000;
  88                 if (tbl >= 1000000000) {
  89                         tbh++;
  90                         tbl -= 1000000000;
  91                 }
  92                 __asm volatile ("1: mfspr %0,%3; cmplw %0,%1; blt 1b; bgt 2f;"
  93                     "mfspr %0,%4; cmplw %0,%2; blt 1b; 2:"
  94                     : "=&r"(scratch)
  95                     : "r"(tbh), "r"(tbl), "n"(SPR_RTCU_R), "n"(SPR_RTCL_R));
  96         } else {
  97                 tb = mftb();
  98                 tb += (n * 1000 + ns_per_tick - 1) / ns_per_tick;
  99                 tbh = tb >> 32;
 100                 tbl = tb;
 101                 __asm volatile ("1: mftbu %0; cmpw %0,%1; blt 1b; bgt 2f;"
 102                                   "mftb %0; cmpw %0,%2; blt 1b; 2:"
 103                                   : "=&r"(scratch)
 104                                   : "r"(tbh), "r"(tbl));
 105         }
 106 }