reactos/hal/halx86/udelay.c

   1 /*
   2  * ReactOS kernel
   3  * Copyright (C) 2000 David Welch <welch@cwcom.net>
   4  * Copyright (C) 1999 Gareth Owen <gaz@athene.co.uk>, Ramon von Handel
   5  * Copyright (C) 1991, 1992 Linus Torvalds
   6  *
   7  * This software is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License as
   9  * published by the Free Software Foundation; either version 2 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This software is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this software; see the file COPYING. If not, write
  19  * to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge,
  20  * MA 02139, USA.
  21  *
  22  */
  23 /* $Id: udelay.c,v 1.2 2002/09/07 15:12:10 chorns Exp $
  24  *
  25  * PROJECT:        ReactOS kernel
  26  * FILE:           ntoskrnl/hal/x86/udelay.c
  27  * PURPOSE:        Busy waiting
  28  * PROGRAMMER:     David Welch (david.welch@seh.ox.ac.uk)
  29  * UPDATE HISTORY:
  30  *                 06/11/99 Created
  31  */
  32
  33 /* INCLUDES ***************************************************************/
  34
  35 #include <hal.h>
  36
  37 #define NDEBUG
  38 #include <internal/debug.h>
  39
  40
  41 /* GLOBALS ******************************************************************/
  42
  43 static unsigned int delay_count = 1;
  44
  45 #define MILLISEC     (10)
  46 #define FREQ         (1000/MILLISEC)
  47
  48 #define PRECISION    (8)
  49
  50 #define         TMR_CTRL        0x43    /*      I/O for control         */
  51 #define         TMR_CNT0        0x40    /*      I/O for counter 0       */
  52 #define         TMR_CNT1        0x41    /*      I/O for counter 1       */
  53 #define         TMR_CNT2        0x42    /*      I/O for counter 2       */
  54
  55 #define         TMR_SC0         0       /*      Select channel 0        */
  56 #define         TMR_SC1         0x40    /*      Select channel 1        */
  57 #define         TMR_SC2         0x80    /*      Select channel 2        */
  58
  59 #define         TMR_LOW         0x10    /*      RW low byte only        */
  60 #define         TMR_HIGH        0x20    /*      RW high byte only       */
  61 #define         TMR_BOTH        0x30    /*      RW both bytes           */
  62
  63 #define         TMR_MD0         0       /*      Mode 0                  */
  64 #define         TMR_MD1         0x2     /*      Mode 1                  */
  65 #define         TMR_MD2         0x4     /*      Mode 2                  */
  66 #define         TMR_MD3         0x6     /*      Mode 3                  */
  67 #define         TMR_MD4         0x8     /*      Mode 4                  */
  68 #define         TMR_MD5         0xA     /*      Mode 5                  */
  69
  70 #define         TMR_BCD         1       /*      BCD mode                */
  71
  72 #define         TMR_LATCH       0       /*      Latch command           */
  73
  74 #define         TMR_READ        0xF0    /*    Read command              */
  75 #define         TMR_CNT         0x20    /*    CNT bit  (Active low, subtract it) */
  76 #define         TMR_STAT        0x10    /*    Status bit  (Active low, subtract it) */
  77 #define         TMR_CH2         0x8     /*    Channel 2 bit             */
  78 #define         TMR_CH1         0x4     /*    Channel 1 bit             */
  79 #define         TMR_CH0         0x2     /*    Channel 0 bit             */
  80
  81 static BOOLEAN UdelayCalibrated = FALSE;
  82
  83 /* FUNCTIONS **************************************************************/
  84
  85 void init_pit(float h, unsigned char channel)
  86 {
  87         unsigned int temp=0;
  88
  89         temp = 1193180/h;
  90
  91 //      WRITE_PORT_UCHAR((PUCHAR)TMR_CTRL,
  92 //                       (channel*0x40) + TMR_BOTH + TMR_MD3);
  93         WRITE_PORT_UCHAR((PUCHAR)TMR_CTRL,
  94                          (channel*0x40) + TMR_BOTH + TMR_MD2);
  95         WRITE_PORT_UCHAR((PUCHAR)(0x40+channel),
  96                          (unsigned char) temp);
  97         WRITE_PORT_UCHAR((PUCHAR)(0x40+channel),
  98                          (unsigned char) (temp>>8));
  99 }
 100
 101 VOID STDCALL
 102 __KeStallExecutionProcessor(ULONG Loops)
 103 {
 104    register unsigned int i;
 105    for (i=0; i<Loops;i++);
 106 }
 107
 108 VOID STDCALL KeStallExecutionProcessor(ULONG Microseconds)
 109 {
 110    __KeStallExecutionProcessor((delay_count*Microseconds)/1000);
 111 }
 112
 113 #define HZ (100)
 114 #define CLOCK_TICK_RATE (1193182)
 115 #define LATCH (CLOCK_TICK_RATE / HZ)
 116
 117 static ULONG Read8254Timer(VOID)
 118 {
 119         ULONG Count;
 120
 121         WRITE_PORT_UCHAR((PUCHAR)0x43, 0x00);
 122         Count = READ_PORT_UCHAR((PUCHAR)0x40);
 123         Count |= READ_PORT_UCHAR((PUCHAR)0x40) << 8;
 124         return Count;
 125 }
 126
 127
 128 static VOID WaitFor8254Wraparound(VOID)
 129 {
 130         ULONG CurCount, PrevCount = ~0;
 131         LONG Delta;
 132
 133         CurCount = Read8254Timer();
 134
 135         do {
 136                 PrevCount = CurCount;
 137                 CurCount = Read8254Timer();
 138                 Delta = CurCount - PrevCount;
 139
 140         /*
 141          * This limit for delta seems arbitrary, but it isn't, it's
 142          * slightly above the level of error a buggy Mercury/Neptune
 143          * chipset timer can cause.
 144          */
 145
 146         } while (Delta < 300);
 147 }
 148
 149 VOID HalpCalibrateStallExecution(VOID)
 150 {
 151    ULONG i;
 152    ULONG calib_bit;
 153          ULONG CurCount;
 154
 155    if (UdelayCalibrated)
 156       return;
 157
 158    UdelayCalibrated = TRUE;
 159
 160    DbgPrint("Calibrating delay loop... [");
 161
 162    /* Initialise timer interrupt with MILLISECOND ms interval        */
 163    WRITE_PORT_UCHAR((PUCHAR)0x43, 0x34);  /* binary, mode 2, LSB/MSB, ch 0 */
 164    WRITE_PORT_UCHAR((PUCHAR)0x40, LATCH & 0xff); /* LSB */
 165    WRITE_PORT_UCHAR((PUCHAR)0x40, LATCH >> 8); /* MSB */
 166
 167    /* Stage 1:  Coarse calibration                                   */
 168
 169    WaitFor8254Wraparound();
 170
 171    delay_count = 1;
 172
 173    do {
 174       delay_count <<= 1;                  /* Next delay count to try */
 175
 176       WaitFor8254Wraparound();
 177
 178       __KeStallExecutionProcessor(delay_count);      /* Do the delay */
 179
 180             CurCount = Read8254Timer();
 181    } while (CurCount > LATCH / 2);
 182
 183    delay_count >>= 1;              /* Get bottom value for delay     */
 184
 185    /* Stage 2:  Fine calibration                                     */
 186    DbgPrint("delay_count: %d", delay_count);
 187
 188    calib_bit = delay_count;        /* Which bit are we going to test */
 189
 190    for(i=0;i<PRECISION;i++) {
 191       calib_bit >>= 1;             /* Next bit to calibrate          */
 192       if(!calib_bit) break;        /* If we have done all bits, stop */
 193
 194       delay_count |= calib_bit;        /* Set the bit in delay_count */
 195
 196       WaitFor8254Wraparound();
 197
 198       __KeStallExecutionProcessor(delay_count);      /* Do the delay */
 199
 200       CurCount = Read8254Timer();
 201       if (CurCount <= LATCH / 2)   /* If a tick has passed, turn the */
 202         delay_count &= ~calib_bit; /* calibrated bit back off        */
 203    }
 204
 205    /* We're finished:  Do the finishing touches                      */
 206
 207    delay_count /= (MILLISEC / 2);   /* Calculate delay_count for 1ms */
 208
 209    DbgPrint("]\n");
 210    DbgPrint("delay_count: %d\n", delay_count);
 211    DbgPrint("CPU speed: %d\n", delay_count/250);
 212 #if 0
 213    DbgPrint("About to start delay loop test\n");
 214    DbgPrint("Waiting for five minutes...");
 215    for (i = 0; i < (5*60*1000*20); i++)
 216      {
 217         KeStallExecutionProcessor(50);
 218      }
 219    DbgPrint("finished\n");
 220    for(;;);
 221 #endif
 222 }
 223
 224 /* EOF */