drivers/acpi/acpica/hwtimer.c

   1
   2 /******************************************************************************
   3  *
   4  * Name: hwtimer.c - ACPI Power Management Timer Interface
   5  *
   6  *****************************************************************************/
   7
   8 /*
   9  * Copyright (C) 2000 - 2012, Intel Corp.
  10  * All rights reserved.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions, and the following disclaimer,
  17  *    without modification.
  18  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
  19  *    substantially similar to the "NO WARRANTY" disclaimer below
  20  *    ("Disclaimer") and any redistribution must be conditioned upon
  21  *    including a substantially similar Disclaimer requirement for further
  22  *    binary redistribution.
  23  * 3. Neither the names of the above-listed copyright holders nor the names
  24  *    of any contributors may be used to endorse or promote products derived
  25  *    from this software without specific prior written permission.
  26  *
  27  * Alternatively, this software may be distributed under the terms of the
  28  * GNU General Public License ("GPL") version 2 as published by the Free
  29  * Software Foundation.
  30  *
  31  * NO WARRANTY
  32  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  33  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  34  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
  35  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  36  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  37  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  38  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  39  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  40  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  41  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  42  * POSSIBILITY OF SUCH DAMAGES.
  43  */
  44
  45 #include <linux/export.h>
  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         status =
 105             acpi_hw_read(ticks, &acpi_gbl_FADT.xpm_timer_block);
 106
 107         return_ACPI_STATUS(status);
 108 }
 109
 110 ACPI_EXPORT_SYMBOL(acpi_get_timer)
 111
 112 /******************************************************************************
 113  *
 114  * FUNCTION:    acpi_get_timer_duration
 115  *
 116  * PARAMETERS:  start_ticks         - Starting timestamp
 117  *              end_ticks           - End timestamp
 118  *              time_elapsed        - Where the elapsed time is returned
 119  *
 120  * RETURN:      Status and time_elapsed
 121  *
 122  * DESCRIPTION: Computes the time elapsed (in microseconds) between two
 123  *              PM Timer time stamps, taking into account the possibility of
 124  *              rollovers, the timer resolution, and timer frequency.
 125  *
 126  *              The PM Timer's clock ticks at roughly 3.6 times per
 127  *              _microsecond_, and its clock continues through Cx state
 128  *              transitions (unlike many CPU timestamp counters) -- making it
 129  *              a versatile and accurate timer.
 130  *
 131  *              Note that this function accommodates only a single timer
 132  *              rollover.  Thus for 24-bit timers, this function should only
 133  *              be used for calculating durations less than ~4.6 seconds
 134  *              (~20 minutes for 32-bit timers) -- calculations below:
 135  *
 136  *              2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
 137  *              2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
 138  *
 139  ******************************************************************************/
 140 acpi_status
 141 acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 * time_elapsed)
 142 {
 143         acpi_status status;
 144         u32 delta_ticks;
 145         u64 quotient;
 146
 147         ACPI_FUNCTION_TRACE(acpi_get_timer_duration);
 148
 149         if (!time_elapsed) {
 150                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 151         }
 152
 153         /*
 154          * Compute Tick Delta:
 155          * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
 156          */
 157         if (start_ticks < end_ticks) {
 158                 delta_ticks = end_ticks - start_ticks;
 159         } else if (start_ticks > end_ticks) {
 160                 if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
 161
 162                         /* 24-bit Timer */
 163
 164                         delta_ticks =
 165                             (((0x00FFFFFF - start_ticks) +
 166                               end_ticks) & 0x00FFFFFF);
 167                 } else {
 168                         /* 32-bit Timer */
 169
 170                         delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks;
 171                 }
 172         } else {                /* start_ticks == end_ticks */
 173
 174                 *time_elapsed = 0;
 175                 return_ACPI_STATUS(AE_OK);
 176         }
 177
 178         /*
 179          * Compute Duration (Requires a 64-bit multiply and divide):
 180          *
 181          * time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY;
 182          */
 183         status = acpi_ut_short_divide(((u64) delta_ticks) * 1000000,
 184                                       PM_TIMER_FREQUENCY, &quotient, NULL);
 185
 186         *time_elapsed = (u32) quotient;
 187         return_ACPI_STATUS(status);
 188 }
 189
 190 ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
 191 #endif                          /* !ACPI_REDUCED_HARDWARE */