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