1 2/****************************************************************************** 3 * 4 * Name: hwtimer.c - ACPI Power Management Timer Interface 5 * 6 *****************************************************************************/ 7 8/* 9 * Copyright (C) 2000 - 2007, R. Byron Moore 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 <acpi/acpi.h> 46 47#define _COMPONENT ACPI_HARDWARE 48ACPI_MODULE_NAME("hwtimer") 49 50/****************************************************************************** 51 * 52 * FUNCTION: acpi_get_timer_resolution 53 * 54 * PARAMETERS: Resolution - Where the resolution is returned 55 * 56 * RETURN: Status and timer resolution 57 * 58 * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits). 59 * 60 ******************************************************************************/ 61acpi_status acpi_get_timer_resolution(u32 * resolution) 62{ 63 ACPI_FUNCTION_TRACE(acpi_get_timer_resolution); 64 65 if (!resolution) { 66 return_ACPI_STATUS(AE_BAD_PARAMETER); 67 } 68 69 if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) { 70 *resolution = 24; 71 } else { 72 *resolution = 32; 73 } 74 75 return_ACPI_STATUS(AE_OK); 76} 77 78ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution) 79 80/****************************************************************************** 81 * 82 * FUNCTION: acpi_get_timer 83 * 84 * PARAMETERS: Ticks - Where the timer value is returned 85 * 86 * RETURN: Status and current timer value (ticks) 87 * 88 * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks). 89 * 90 ******************************************************************************/ 91acpi_status acpi_get_timer(u32 * ticks) 92{ 93 acpi_status status; 94 95 ACPI_FUNCTION_TRACE(acpi_get_timer); 96 97 if (!ticks) { 98 return_ACPI_STATUS(AE_BAD_PARAMETER); 99 } 100 101 status = 102 acpi_hw_low_level_read(32, ticks, &acpi_gbl_FADT.xpm_timer_block); 103 104 return_ACPI_STATUS(status); 105} 106 107ACPI_EXPORT_SYMBOL(acpi_get_timer) 108 109/****************************************************************************** 110 * 111 * FUNCTION: acpi_get_timer_duration 112 * 113 * PARAMETERS: start_ticks - Starting timestamp 114 * end_ticks - End timestamp 115 * time_elapsed - Where the elapsed time is returned 116 * 117 * RETURN: Status and time_elapsed 118 * 119 * DESCRIPTION: Computes the time elapsed (in microseconds) between two 120 * PM Timer time stamps, taking into account the possibility of 121 * rollovers, the timer resolution, and timer frequency. 122 * 123 * The PM Timer's clock ticks at roughly 3.6 times per 124 * _microsecond_, and its clock continues through Cx state 125 * transitions (unlike many CPU timestamp counters) -- making it 126 * a versatile and accurate timer. 127 * 128 * Note that this function accommodates only a single timer 129 * rollover. Thus for 24-bit timers, this function should only 130 * be used for calculating durations less than ~4.6 seconds 131 * (~20 minutes for 32-bit timers) -- calculations below: 132 * 133 * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec 134 * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes 135 * 136 ******************************************************************************/ 137acpi_status 138acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 * time_elapsed) 139{ 140 acpi_status status; 141 u32 delta_ticks; 142 acpi_integer quotient; 143 144 ACPI_FUNCTION_TRACE(acpi_get_timer_duration); 145 146 if (!time_elapsed) { 147 return_ACPI_STATUS(AE_BAD_PARAMETER); 148 } 149 150 /* 151 * Compute Tick Delta: 152 * Handle (max one) timer rollovers on 24-bit versus 32-bit timers. 153 */ 154 if (start_ticks < end_ticks) { 155 delta_ticks = end_ticks - start_ticks; 156 } else if (start_ticks > end_ticks) { 157 if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) { 158 159 /* 24-bit Timer */ 160 161 delta_ticks = 162 (((0x00FFFFFF - start_ticks) + 163 end_ticks) & 0x00FFFFFF); 164 } else { 165 /* 32-bit Timer */ 166 167 delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks; 168 } 169 } else { /* start_ticks == end_ticks */ 170 171 *time_elapsed = 0; 172 return_ACPI_STATUS(AE_OK); 173 } 174 175 /* 176 * Compute Duration (Requires a 64-bit multiply and divide): 177 * 178 * time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY; 179 */ 180 status = acpi_ut_short_divide(((u64) delta_ticks) * 1000000, 181 PM_TIMER_FREQUENCY, "ient, NULL); 182 183 *time_elapsed = (u32) quotient; 184 return_ACPI_STATUS(status); 185} 186 187ACPI_EXPORT_SYMBOL(acpi_get_timer_duration) 188