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  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 */
  203.