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         /* ACPI 5.0A: PM Timer is optional */
 104
 105         if (!acpi_gbl_FADT.xpm_timer_block.address) {
 106                 return_ACPI_STATUS(AE_SUPPORT);
 107         }
 108
 109         status = acpi_hw_read(ticks, &acpi_gbl_FADT.xpm_timer_block);
 110         return_ACPI_STATUS(status);
 111 }
 112
 113 ACPI_EXPORT_SYMBOL(acpi_get_timer)
 114
 115 /******************************************************************************
 116  *
 117  * FUNCTION:    acpi_get_timer_duration
 118  *
 119  * PARAMETERS:  start_ticks         - Starting timestamp
 120  *              end_ticks           - End timestamp
 121  *              time_elapsed        - Where the elapsed time is returned
 122  *
 123  * RETURN:      Status and time_elapsed
 124  *
 125  * DESCRIPTION: Computes the time elapsed (in microseconds) between two
 126  *              PM Timer time stamps, taking into account the possibility of
 127  *              rollovers, the timer resolution, and timer frequency.
 128  *
 129  *              The PM Timer's clock ticks at roughly 3.6 times per
 130  *              _microsecond_, and its clock continues through Cx state
 131  *              transitions (unlike many CPU timestamp counters) -- making it
 132  *              a versatile and accurate timer.
 133  *
 134  *              Note that this function accommodates only a single timer
 135  *              rollover. Thus for 24-bit timers, this function should only
 136  *              be used for calculating durations less than ~4.6 seconds
 137  *              (~20 minutes for 32-bit timers) -- calculations below:
 138  *
 139  *              2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
 140  *              2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
 141  *
 142  ******************************************************************************/
 143 acpi_status
 144 acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 * time_elapsed)
 145 {
 146         acpi_status status;
 147         u32 delta_ticks;
 148         u64 quotient;
 149
 150         ACPI_FUNCTION_TRACE(acpi_get_timer_duration);
 151
 152         if (!time_elapsed) {
 153                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 154         }
 155
 156         /* ACPI 5.0A: PM Timer is optional */
 157
 158         if (!acpi_gbl_FADT.xpm_timer_block.address) {
 159                 return_ACPI_STATUS(AE_SUPPORT);
 160         }
 161
 162         /*
 163          * Compute Tick Delta:
 164          * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
 165          */
 166         if (start_ticks < end_ticks) {
 167                 delta_ticks = end_ticks - start_ticks;
 168         } else if (start_ticks > end_ticks) {
 169                 if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
 170
 171                         /* 24-bit Timer */
 172
 173                         delta_ticks =
 174                             (((0x00FFFFFF - start_ticks) +
 175                               end_ticks) & 0x00FFFFFF);
 176                 } else {
 177                         /* 32-bit Timer */
 178
 179                         delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks;
 180                 }
 181         } else {                /* start_ticks == end_ticks */
 182
 183                 *time_elapsed = 0;
 184                 return_ACPI_STATUS(AE_OK);
 185         }
 186
 187         /*
 188          * Compute Duration (Requires a 64-bit multiply and divide):
 189          *
 190          * time_elapsed (microseconds) =
 191          *  (delta_ticks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY;
 192          */
 193         status = acpi_ut_short_divide(((u64)delta_ticks) * ACPI_USEC_PER_SEC,
 194                                       ACPI_PM_TIMER_FREQUENCY, &quotient, NULL);
 195
 196         *time_elapsed = (u32) quotient;
 197         return_ACPI_STATUS(status);
 198 }
 199
 200 ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
 201 #endif                          /* !ACPI_REDUCED_HARDWARE */