reactos/hal/halx86/generic/timer.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 /* $Id$
  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 #define NDEBUG
  36 #include <hal.h>
  37
  38 /* GLOBALS ******************************************************************/
  39
  40 #define         TMR_CTRL        0x43    /*      I/O for control         */
  41 #define         TMR_CNT0        0x40    /*      I/O for counter 0       */
  42 #define         TMR_CNT1        0x41    /*      I/O for counter 1       */
  43 #define         TMR_CNT2        0x42    /*      I/O for counter 2       */
  44
  45 #define         TMR_SC0         0       /*      Select channel 0        */
  46 #define         TMR_SC1         0x40    /*      Select channel 1        */
  47 #define         TMR_SC2         0x80    /*      Select channel 2        */
  48
  49 #define         TMR_LOW         0x10    /*      RW low byte only        */
  50 #define         TMR_HIGH        0x20    /*      RW high byte only       */
  51 #define         TMR_BOTH        0x30    /*      RW both bytes           */
  52
  53 #define         TMR_MD0         0       /*      Mode 0                  */
  54 #define         TMR_MD1         0x2     /*      Mode 1                  */
  55 #define         TMR_MD2         0x4     /*      Mode 2                  */
  56 #define         TMR_MD3         0x6     /*      Mode 3                  */
  57 #define         TMR_MD4         0x8     /*      Mode 4                  */
  58 #define         TMR_MD5         0xA     /*      Mode 5                  */
  59
  60 #define         TMR_BCD         1       /*      BCD mode                */
  61
  62 #define         TMR_LATCH       0       /*      Latch command           */
  63
  64 #define         TMR_READ        0xF0    /*    Read command              */
  65 #define         TMR_CNT         0x20    /*    CNT bit  (Active low, subtract it) */
  66 #define         TMR_STAT        0x10    /*    Status bit  (Active low, subtract it) */
  67 #define         TMR_CH2         0x8     /*    Channel 2 bit             */
  68 #define         TMR_CH1         0x4     /*    Channel 1 bit             */
  69 #define         TMR_CH0         0x2     /*    Channel 0 bit             */
  70
  71 #define MILLISEC        10                     /* Number of millisec between interrupts */
  72 #define HZ              (1000 / MILLISEC)      /* Number of interrupts per second */
  73 #define CLOCK_TICK_RATE 1193182                /* Clock frequency of the timer chip */
  74 #define LATCH           (CLOCK_TICK_RATE / HZ) /* Count to program into the timer chip */
  75 #define PRECISION       8                      /* Number of bits to calibrate for delay loop */
  76
  77 static BOOLEAN UdelayCalibrated = FALSE;
  78
  79 /* FUNCTIONS **************************************************************/
  80
  81 /*
  82  * NOTE: This function MUST NOT be optimized by the compiler!
  83  * If it is, it obviously will not delay AT ALL, and the system
  84  * will appear completely frozen at boot since
  85  * HalpCalibrateStallExecution will never return.
  86  * There are three options to stop optimization:
  87  * 1. Use a volatile automatic variable. Making it delay quite a bit
  88  *    due to memory accesses, and keeping the code portable. However,
  89  *    as this involves memory access it depends on both the CPU cache,
  90  *    e.g. if the stack used is already in a cache line or not, and
  91  *    whether or not we're MP. If MP, another CPU could (probably would)
  92  *    also access RAM at the same time - making the delay imprecise.
  93  * 2. Use compiler-specific #pragma's to disable optimization.
  94  * 3. Use inline assembly, making it equally unportable as #2.
  95  * For supported compilers we use inline assembler. For the others,
  96  * portable plain C.
  97  */
  98 VOID STDCALL __attribute__((noinline))
  99 __KeStallExecutionProcessor(ULONG Loops)
 100 {
 101   if (!Loops)
 102   {
 103     return;
 104   }
 105 #if defined(__GNUC__)
 106   __asm__ __volatile__ (
 107     "mov %0, %%eax\n"
 108     "ROSL1: dec %%eax\n"
 109     "jnz ROSL1" : : "d" (Loops));
 110
 111 #elif defined(_MSC_VER)
 112   __asm mov eax, Loops
 113 ROSL1:
 114   __asm dec eax
 115   __asm jnz ROSL1
 116 #else
 117    volatile unsigned int target = Loops;
 118    unsigned int i;
 119    for (i=0; i<target;i++);
 120 #endif
 121 }
 122
 123 VOID STDCALL KeStallExecutionProcessor(ULONG Microseconds)
 124 {
 125    PKIPCR Pcr = (PKIPCR)KeGetCurrentKPCR();
 126
 127    if (Pcr->PrcbData.FeatureBits & X86_FEATURE_TSC)
 128    {
 129       LARGE_INTEGER EndCount, CurrentCount;
 130       Ki386RdTSC(EndCount);
 131       EndCount.QuadPart += Microseconds * (ULONGLONG)Pcr->PrcbData.MHz;
 132       do
 133       {
 134          Ki386RdTSC(CurrentCount);
 135       }
 136       while (CurrentCount.QuadPart < EndCount.QuadPart);
 137    }
 138    else
 139    {
 140       __KeStallExecutionProcessor((Pcr->StallScaleFactor*Microseconds)/1000);
 141    }
 142 }
 143
 144 static ULONG Read8254Timer(VOID)
 145 {
 146   ULONG Count;
 147   ULONG flags;
 148
 149   /* save flags and disable interrupts */
 150   Ki386SaveFlags(flags);
 151   Ki386DisableInterrupts();
 152
 153   WRITE_PORT_UCHAR((PUCHAR) TMR_CTRL, TMR_SC0 | TMR_LATCH);
 154   Count = READ_PORT_UCHAR((PUCHAR) TMR_CNT0);
 155   Count |= READ_PORT_UCHAR((PUCHAR) TMR_CNT0) << 8;
 156
 157   /* restore flags */
 158   Ki386RestoreFlags(flags);
 159
 160   return Count;
 161 }
 162
 163
 164 VOID WaitFor8254Wraparound(VOID)
 165 {
 166   ULONG CurCount, PrevCount = ~0;
 167   LONG Delta;
 168
 169   CurCount = Read8254Timer();
 170
 171   do
 172     {
 173       PrevCount = CurCount;
 174       CurCount = Read8254Timer();
 175       Delta = CurCount - PrevCount;
 176
 177       /*
 178        * This limit for delta seems arbitrary, but it isn't, it's
 179        * slightly above the level of error a buggy Mercury/Neptune
 180        * chipset timer can cause.
 181        */
 182
 183     }
 184    while (Delta < 300);
 185 }
 186
 187 VOID HalpCalibrateStallExecution(VOID)
 188 {
 189   ULONG i;
 190   ULONG calib_bit;
 191   ULONG CurCount;
 192   PKIPCR Pcr;
 193   LARGE_INTEGER StartCount, EndCount;
 194
 195   if (UdelayCalibrated)
 196     {
 197       return;
 198     }
 199
 200   UdelayCalibrated = TRUE;
 201   Pcr = (PKIPCR)KeGetCurrentKPCR();
 202
 203   /* Initialise timer interrupt with MILLISEC ms interval        */
 204   WRITE_PORT_UCHAR((PUCHAR) TMR_CTRL, TMR_SC0 | TMR_BOTH | TMR_MD2);  /* binary, mode 2, LSB/MSB, ch 0 */
 205   WRITE_PORT_UCHAR((PUCHAR) TMR_CNT0, LATCH & 0xff); /* LSB */
 206   WRITE_PORT_UCHAR((PUCHAR) TMR_CNT0, LATCH >> 8); /* MSB */
 207
 208   if (Pcr->PrcbData.FeatureBits & X86_FEATURE_TSC)
 209   {
 210
 211      WaitFor8254Wraparound();
 212      Ki386RdTSC(StartCount);
 213
 214      WaitFor8254Wraparound();
 215      Ki386RdTSC(EndCount);
 216
 217      Pcr->PrcbData.MHz = (ULONG)(EndCount.QuadPart - StartCount.QuadPart) / 10000;
 218      DPRINT("%dMHz\n", Pcr->PrcbData.MHz);
 219      return;
 220
 221   }
 222
 223   DbgPrint("Calibrating delay loop... [");
 224
 225   /* Stage 1:  Coarse calibration                                           */
 226
 227   WaitFor8254Wraparound();
 228
 229   Pcr->StallScaleFactor = 1;
 230
 231   do
 232     {
 233       Pcr->StallScaleFactor <<= 1;              /* Next delay count to try  */
 234
 235       WaitFor8254Wraparound();
 236
 237       __KeStallExecutionProcessor(Pcr->StallScaleFactor);   /* Do the delay */
 238
 239       CurCount = Read8254Timer();
 240     }
 241   while (CurCount > LATCH / 2);
 242
 243   Pcr->StallScaleFactor >>= 1;              /* Get bottom value for delay   */
 244
 245   /* Stage 2:  Fine calibration                                             */
 246   DbgPrint("delay_count: %d", Pcr->StallScaleFactor);
 247
 248   calib_bit = Pcr->StallScaleFactor;    /* Which bit are we going to test   */
 249
 250   for (i = 0; i < PRECISION; i++)
 251     {
 252       calib_bit >>= 1;                          /* Next bit to calibrate    */
 253       if (!calib_bit)
 254         {
 255           break;                        /* If we have done all bits, stop   */
 256         }
 257
 258       Pcr->StallScaleFactor |= calib_bit;   /* Set the bit in delay_count   */
 259
 260       WaitFor8254Wraparound();
 261
 262       __KeStallExecutionProcessor(Pcr->StallScaleFactor);   /* Do the delay */
 263
 264       CurCount = Read8254Timer();
 265       if (CurCount <= LATCH / 2)        /* If a tick has passed, turn the   */
 266         {                               /* calibrated bit back off          */
 267           Pcr->StallScaleFactor &= ~calib_bit;
 268         }
 269     }
 270
 271   /* We're finished:  Do the finishing touches                              */
 272
 273   Pcr->StallScaleFactor /= (MILLISEC / 2);  /* Calculate delay_count for 1ms */
 274
 275   DbgPrint("]\n");
 276   DbgPrint("delay_count: %d\n", Pcr->StallScaleFactor);
 277   DbgPrint("CPU speed: %d\n", Pcr->StallScaleFactor / 250);
 278 #if 0
 279   DbgPrint("About to start delay loop test\n");
 280   DbgPrint("Waiting for five minutes...");
 281   for (i = 0; i < (5*60*1000*20); i++)
 282     {
 283       KeStallExecutionProcessor(50);
 284     }
 285   DbgPrint("finished\n");
 286   for(;;);
 287 #endif
 288 }
 289
 290
 291 VOID STDCALL
 292 HalCalibratePerformanceCounter(ULONG Count)
 293 {
 294    ULONG flags;
 295
 296    /* save flags and disable interrupts */
 297    Ki386SaveFlags(flags);
 298    Ki386DisableInterrupts();
 299
 300    __KeStallExecutionProcessor(Count);
 301
 302    /* restore flags */
 303    Ki386RestoreFlags(flags);
 304 }
 305
 306
 307 LARGE_INTEGER STDCALL
 308 KeQueryPerformanceCounter(PLARGE_INTEGER PerformanceFreq)
 309 /*
 310  * FUNCTION: Queries the finest grained running count available in the system
 311  * ARGUMENTS:
 312  *         PerformanceFreq (OUT) = The routine stores the number of
 313  *                                 performance counter ticks per second here
 314  * RETURNS: The number of performance counter ticks since boot
 315  */
 316 {
 317   PKIPCR Pcr;
 318   LARGE_INTEGER Value;
 319   ULONG Flags;
 320
 321   Ki386SaveFlags(Flags);
 322   Ki386DisableInterrupts();
 323
 324   Pcr = (PKIPCR)KeGetCurrentKPCR();
 325
 326   if (Pcr->PrcbData.FeatureBits & X86_FEATURE_TSC)
 327   {
 328      Ki386RestoreFlags(Flags);
 329      if (NULL != PerformanceFreq)
 330      {
 331         PerformanceFreq->QuadPart = Pcr->PrcbData.MHz * (ULONGLONG)1000000;
 332      }
 333      Ki386RdTSC(Value);
 334   }
 335   else
 336   {
 337      LARGE_INTEGER TicksOld;
 338      LARGE_INTEGER TicksNew;
 339      ULONG CountsLeft;
 340
 341      Ki386RestoreFlags(Flags);
 342
 343      if (NULL != PerformanceFreq)
 344      {
 345         PerformanceFreq->QuadPart = CLOCK_TICK_RATE;
 346      }
 347
 348      do
 349      {
 350         KeQueryTickCount(&TicksOld);
 351         CountsLeft = Read8254Timer();
 352         Value.QuadPart = TicksOld.QuadPart * LATCH + (LATCH - CountsLeft);
 353         KeQueryTickCount(&TicksNew);
 354      }
 355      while (TicksOld.QuadPart != TicksNew.QuadPart);
 356   }
 357   return Value;
 358 }
 359
 360 /* EOF */