1 2 /****************************************************************************** 3 * 4 * Name: hwtimer.c - ACPI Power Management Timer Interface 5 * 6 *****************************************************************************/ 7 8 /* 9 * Copyright (C) 2000 - 2010, 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 <acpi/acpi.h> 46 #include "accommon.h" 47 48 #define _COMPONENT ACPI_HARDWARE 49 ACPI_MODULE_NAME("hwtimer") 50 51 /****************************************************************************** 52 * 53 * FUNCTION: acpi_get_timer_resolution 54 * 55 * PARAMETERS: Resolution - Where the resolution is returned 56 * 57 * RETURN: Status and timer resolution 58 * 59 * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits). 60 * 61 ******************************************************************************/ 62 acpi_status acpi_get_timer_resolution(u32 * resolution) 63 { 64 ACPI_FUNCTION_TRACE(acpi_get_timer_resolution); 65 66 if (!resolution) { 67 return_ACPI_STATUS(AE_BAD_PARAMETER); 68 } 69 70 if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) { 71 *resolution = 24; 72 } else { 73 *resolution = 32; 74 } 75 76 return_ACPI_STATUS(AE_OK); 77 } 78 79 ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution) 80 81 /****************************************************************************** 82 * 83 * FUNCTION: acpi_get_timer 84 * 85 * PARAMETERS: Ticks - Where the timer value is returned 86 * 87 * RETURN: Status and current timer value (ticks) 88 * 89 * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks). 90 * 91 ******************************************************************************/ 92 acpi_status acpi_get_timer(u32 * ticks) 93 { 94 acpi_status status; 95 96 ACPI_FUNCTION_TRACE(acpi_get_timer); 97 98 if (!ticks) { 99 return_ACPI_STATUS(AE_BAD_PARAMETER); 100 } 101 102 status = 103 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 = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY; 180 */ 181 status = acpi_ut_short_divide(((u64) delta_ticks) * 1000000, 182 PM_TIMER_FREQUENCY, "ient, NULL); 183 184 *time_elapsed = (u32) quotient; 185 return_ACPI_STATUS(status); 186 } 187 188 ACPI_EXPORT_SYMBOL(acpi_get_timer_duration) 189