drivers/acpi/acpica/hwtimer.c

   1 /******************************************************************************
   2  *
   3  * Name: hwtimer.c - ACPI Power Management Timer Interface
   4  *
   5  *****************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2015, 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/acpi.h>
  47 #include "accommon.h"
  48
  49 #define _COMPONENT          ACPI_HARDWARE
  50 ACPI_MODULE_NAME("hwtimer")
  51
  52 #if (!ACPI_REDUCED_HARDWARE)    /* Entire module */
  53 /******************************************************************************
  54  *
  55  * FUNCTION:    acpi_get_timer_resolution
  56  *
  57  * PARAMETERS:  resolution          - Where the resolution is returned
  58  *
  59  * RETURN:      Status and timer resolution
  60  *
  61  * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
  62  *
  63  ******************************************************************************/
  64 acpi_status acpi_get_timer_resolution(u32 * resolution)
  65 {
  66         ACPI_FUNCTION_TRACE(acpi_get_timer_resolution);
  67
  68         if (!resolution) {
  69                 return_ACPI_STATUS(AE_BAD_PARAMETER);
  70         }
  71
  72         if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
  73                 *resolution = 24;
  74         } else {
  75                 *resolution = 32;
  76         }
  77
  78         return_ACPI_STATUS(AE_OK);
  79 }
  80
  81 ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution)
  82
  83 /******************************************************************************
  84  *
  85  * FUNCTION:    acpi_get_timer
  86  *
  87  * PARAMETERS:  ticks               - Where the timer value is returned
  88  *
  89  * RETURN:      Status and current timer value (ticks)
  90  *
  91  * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
  92  *
  93  ******************************************************************************/
  94 acpi_status acpi_get_timer(u32 * ticks)
  95 {
  96         acpi_status status;
  97
  98         ACPI_FUNCTION_TRACE(acpi_get_timer);
  99
 100         if (!ticks) {
 101                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 102         }
 103
 104         /* ACPI 5.0A: PM Timer is optional */
 105
 106         if (!acpi_gbl_FADT.xpm_timer_block.address) {
 107                 return_ACPI_STATUS(AE_SUPPORT);
 108         }
 109
 110         status = acpi_hw_read(ticks, &acpi_gbl_FADT.xpm_timer_block);
 111         return_ACPI_STATUS(status);
 112 }
 113
 114 ACPI_EXPORT_SYMBOL(acpi_get_timer)
 115
 116 /******************************************************************************
 117  *
 118  * FUNCTION:    acpi_get_timer_duration
 119  *
 120  * PARAMETERS:  start_ticks         - Starting timestamp
 121  *              end_ticks           - End timestamp
 122  *              time_elapsed        - Where the elapsed time is returned
 123  *
 124  * RETURN:      Status and time_elapsed
 125  *
 126  * DESCRIPTION: Computes the time elapsed (in microseconds) between two
 127  *              PM Timer time stamps, taking into account the possibility of
 128  *              rollovers, the timer resolution, and timer frequency.
 129  *
 130  *              The PM Timer's clock ticks at roughly 3.6 times per
 131  *              _microsecond_, and its clock continues through Cx state
 132  *              transitions (unlike many CPU timestamp counters) -- making it
 133  *              a versatile and accurate timer.
 134  *
 135  *              Note that this function accommodates only a single timer
 136  *              rollover. Thus for 24-bit timers, this function should only
 137  *              be used for calculating durations less than ~4.6 seconds
 138  *              (~20 minutes for 32-bit timers) -- calculations below:
 139  *
 140  *              2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
 141  *              2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
 142  *
 143  ******************************************************************************/
 144 acpi_status
 145 acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 * time_elapsed)
 146 {
 147         acpi_status status;
 148         u32 delta_ticks;
 149         u64 quotient;
 150
 151         ACPI_FUNCTION_TRACE(acpi_get_timer_duration);
 152
 153         if (!time_elapsed) {
 154                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 155         }
 156
 157         /* ACPI 5.0A: PM Timer is optional */
 158
 159         if (!acpi_gbl_FADT.xpm_timer_block.address) {
 160                 return_ACPI_STATUS(AE_SUPPORT);
 161         }
 162
 163         /*
 164          * Compute Tick Delta:
 165          * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
 166          */
 167         if (start_ticks < end_ticks) {
 168                 delta_ticks = end_ticks - start_ticks;
 169         } else if (start_ticks > end_ticks) {
 170                 if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
 171
 172                         /* 24-bit Timer */
 173
 174                         delta_ticks =
 175                             (((0x00FFFFFF - start_ticks) +
 176                               end_ticks) & 0x00FFFFFF);
 177                 } else {
 178                         /* 32-bit Timer */
 179
 180                         delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks;
 181                 }
 182         } else {                /* start_ticks == end_ticks */
 183
 184                 *time_elapsed = 0;
 185                 return_ACPI_STATUS(AE_OK);
 186         }
 187
 188         /*
 189          * Compute Duration (Requires a 64-bit multiply and divide):
 190          *
 191          * time_elapsed (microseconds) =
 192          *  (delta_ticks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY;
 193          */
 194         status = acpi_ut_short_divide(((u64)delta_ticks) * ACPI_USEC_PER_SEC,
 195                                       ACPI_PM_TIMER_FREQUENCY, &quotient, NULL);
 196
 197         *time_elapsed = (u32) quotient;
 198         return_ACPI_STATUS(status);
 199 }
 200
 201 ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
 202 #endif                          /* !ACPI_REDUCED_HARDWARE */