1 2 /****************************************************************************** 3 * 4 * Name: hwtimer.c - ACPI Power Management Timer Interface 5 * 6 *****************************************************************************/ 7 8 /* 9 * Copyright (C) 2000 - 2011, 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 /****************************************************************************** 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 status = 104 acpi_hw_read(ticks, &acpi_gbl_FADT.xpm_timer_block); 105 106 return_ACPI_STATUS(status); 107 } 108 109 ACPI_EXPORT_SYMBOL(acpi_get_timer) 110 111 /****************************************************************************** 112 * 113 * FUNCTION: acpi_get_timer_duration 114 * 115 * PARAMETERS: start_ticks - Starting timestamp 116 * end_ticks - End timestamp 117 * time_elapsed - Where the elapsed time is returned 118 * 119 * RETURN: Status and time_elapsed 120 * 121 * DESCRIPTION: Computes the time elapsed (in microseconds) between two 122 * PM Timer time stamps, taking into account the possibility of 123 * rollovers, the timer resolution, and timer frequency. 124 * 125 * The PM Timer's clock ticks at roughly 3.6 times per 126 * _microsecond_, and its clock continues through Cx state 127 * transitions (unlike many CPU timestamp counters) -- making it 128 * a versatile and accurate timer. 129 * 130 * Note that this function accommodates only a single timer 131 * rollover. Thus for 24-bit timers, this function should only 132 * be used for calculating durations less than ~4.6 seconds 133 * (~20 minutes for 32-bit timers) -- calculations below: 134 * 135 * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec 136 * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes 137 * 138 ******************************************************************************/ 139 acpi_status 140 acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 * time_elapsed) 141 { 142 acpi_status status; 143 u32 delta_ticks; 144 u64 quotient; 145 146 ACPI_FUNCTION_TRACE(acpi_get_timer_duration); 147 148 if (!time_elapsed) { 149 return_ACPI_STATUS(AE_BAD_PARAMETER); 150 } 151 152 /* 153 * Compute Tick Delta: 154 * Handle (max one) timer rollovers on 24-bit versus 32-bit timers. 155 */ 156 if (start_ticks < end_ticks) { 157 delta_ticks = end_ticks - start_ticks; 158 } else if (start_ticks > end_ticks) { 159 if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) { 160 161 /* 24-bit Timer */ 162 163 delta_ticks = 164 (((0x00FFFFFF - start_ticks) + 165 end_ticks) & 0x00FFFFFF); 166 } else { 167 /* 32-bit Timer */ 168 169 delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks; 170 } 171 } else { /* start_ticks == end_ticks */ 172 173 *time_elapsed = 0; 174 return_ACPI_STATUS(AE_OK); 175 } 176 177 /* 178 * Compute Duration (Requires a 64-bit multiply and divide): 179 * 180 * time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY; 181 */ 182 status = acpi_ut_short_divide(((u64) delta_ticks) * 1000000, 183 PM_TIMER_FREQUENCY, "ient, NULL); 184 185 *time_elapsed = (u32) quotient; 186 return_ACPI_STATUS(status); 187 } 188 189 ACPI_EXPORT_SYMBOL(acpi_get_timer_duration) 190