arch/all-pc/acpica/source/components/hardware/hwtimer.c

   1 /******************************************************************************
   2  *
   3  * Name: hwtimer.c - ACPI Power Management Timer Interface
   4  *
   5  *****************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2013, Intel Corp.
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions, and the following disclaimer,
  16  *    without modification.
  17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
  18  *    substantially similar to the "NO WARRANTY" disclaimer below
  19  *    ("Disclaimer") and any redistribution must be conditioned upon
  20  *    including a substantially similar Disclaimer requirement for further
  21  *    binary redistribution.
  22  * 3. Neither the names of the above-listed copyright holders nor the names
  23  *    of any contributors may be used to endorse or promote products derived
  24  *    from this software without specific prior written permission.
  25  *
  26  * Alternatively, this software may be distributed under the terms of the
  27  * GNU General Public License ("GPL") version 2 as published by the Free
  28  * Software Foundation.
  29  *
  30  * NO WARRANTY
  31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
  34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  41  * POSSIBILITY OF SUCH DAMAGES.
  42  */
  43
  44 #define EXPORT_ACPI_INTERFACES
  45
  46 #include "acpi.h"
  47 #include "accommon.h"
  48
  49 #define _COMPONENT          ACPI_HARDWARE
  50         ACPI_MODULE_NAME    ("hwtimer")
  51
  52
  53 #if (!ACPI_REDUCED_HARDWARE) /* Entire module */
  54 /******************************************************************************
  55  *
  56  * FUNCTION:    AcpiGetTimerResolution
  57  *
  58  * PARAMETERS:  Resolution          - Where the resolution is returned
  59  *
  60  * RETURN:      Status and timer resolution
  61  *
  62  * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
  63  *
  64  ******************************************************************************/
  65
  66 ACPI_STATUS
  67 AcpiGetTimerResolution (
  68     UINT32                  *Resolution)
  69 {
  70     ACPI_FUNCTION_TRACE (AcpiGetTimerResolution);
  71
  72
  73     if (!Resolution)
  74     {
  75         return_ACPI_STATUS (AE_BAD_PARAMETER);
  76     }
  77
  78     if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) == 0)
  79     {
  80         *Resolution = 24;
  81     }
  82     else
  83     {
  84         *Resolution = 32;
  85     }
  86
  87     return_ACPI_STATUS (AE_OK);
  88 }
  89
  90 ACPI_EXPORT_SYMBOL (AcpiGetTimerResolution)
  91
  92
  93 /******************************************************************************
  94  *
  95  * FUNCTION:    AcpiGetTimer
  96  *
  97  * PARAMETERS:  Ticks               - Where the timer value is returned
  98  *
  99  * RETURN:      Status and current timer value (ticks)
 100  *
 101  * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
 102  *
 103  ******************************************************************************/
 104
 105 ACPI_STATUS
 106 AcpiGetTimer (
 107     UINT32                  *Ticks)
 108 {
 109     ACPI_STATUS             Status;
 110
 111
 112     ACPI_FUNCTION_TRACE (AcpiGetTimer);
 113
 114
 115     if (!Ticks)
 116     {
 117         return_ACPI_STATUS (AE_BAD_PARAMETER);
 118     }
 119
 120     /* ACPI 5.0A: PM Timer is optional */
 121
 122     if (!AcpiGbl_FADT.XPmTimerBlock.Address)
 123     {
 124         return_ACPI_STATUS (AE_SUPPORT);
 125     }
 126
 127     Status = AcpiHwRead (Ticks, &AcpiGbl_FADT.XPmTimerBlock);
 128     return_ACPI_STATUS (Status);
 129 }
 130
 131 ACPI_EXPORT_SYMBOL (AcpiGetTimer)
 132
 133
 134 /******************************************************************************
 135  *
 136  * FUNCTION:    AcpiGetTimerDuration
 137  *
 138  * PARAMETERS:  StartTicks          - Starting timestamp
 139  *              EndTicks            - End timestamp
 140  *              TimeElapsed         - Where the elapsed time is returned
 141  *
 142  * RETURN:      Status and TimeElapsed
 143  *
 144  * DESCRIPTION: Computes the time elapsed (in microseconds) between two
 145  *              PM Timer time stamps, taking into account the possibility of
 146  *              rollovers, the timer resolution, and timer frequency.
 147  *
 148  *              The PM Timer's clock ticks at roughly 3.6 times per
 149  *              _microsecond_, and its clock continues through Cx state
 150  *              transitions (unlike many CPU timestamp counters) -- making it
 151  *              a versatile and accurate timer.
 152  *
 153  *              Note that this function accommodates only a single timer
 154  *              rollover. Thus for 24-bit timers, this function should only
 155  *              be used for calculating durations less than ~4.6 seconds
 156  *              (~20 minutes for 32-bit timers) -- calculations below:
 157  *
 158  *              2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
 159  *              2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
 160  *
 161  ******************************************************************************/
 162
 163 ACPI_STATUS
 164 AcpiGetTimerDuration (
 165     UINT32                  StartTicks,
 166     UINT32                  EndTicks,
 167     UINT32                  *TimeElapsed)
 168 {
 169     ACPI_STATUS             Status;
 170     UINT32                  DeltaTicks;
 171     UINT64                  Quotient;
 172
 173
 174     ACPI_FUNCTION_TRACE (AcpiGetTimerDuration);
 175
 176
 177     if (!TimeElapsed)
 178     {
 179         return_ACPI_STATUS (AE_BAD_PARAMETER);
 180     }
 181
 182     /* ACPI 5.0A: PM Timer is optional */
 183
 184     if (!AcpiGbl_FADT.XPmTimerBlock.Address)
 185     {
 186         return_ACPI_STATUS (AE_SUPPORT);
 187     }
 188
 189     /*
 190      * Compute Tick Delta:
 191      * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
 192      */
 193     if (StartTicks < EndTicks)
 194     {
 195         DeltaTicks = EndTicks - StartTicks;
 196     }
 197     else if (StartTicks > EndTicks)
 198     {
 199         if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) == 0)
 200         {
 201             /* 24-bit Timer */
 202
 203             DeltaTicks = (((0x00FFFFFF - StartTicks) + EndTicks) & 0x00FFFFFF);
 204         }
 205         else
 206         {
 207             /* 32-bit Timer */
 208
 209             DeltaTicks = (0xFFFFFFFF - StartTicks) + EndTicks;
 210         }
 211     }
 212     else /* StartTicks == EndTicks */
 213     {
 214         *TimeElapsed = 0;
 215         return_ACPI_STATUS (AE_OK);
 216     }
 217
 218     /*
 219      * Compute Duration (Requires a 64-bit multiply and divide):
 220      *
 221      * TimeElapsed (microseconds) =
 222      *  (DeltaTicks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY;
 223      */
 224     Status = AcpiUtShortDivide (((UINT64) DeltaTicks) * ACPI_USEC_PER_SEC,
 225                 ACPI_PM_TIMER_FREQUENCY, &Quotient, NULL);
 226
 227     *TimeElapsed = (UINT32) Quotient;
 228     return_ACPI_STATUS (Status);
 229 }
 230
 231 ACPI_EXPORT_SYMBOL (AcpiGetTimerDuration)
 232
 233 #endif /* !ACPI_REDUCED_HARDWARE */