1 /****************************************************************************** 2 * 3 * Name: hwtimer.c - ACPI Power Management Timer Interface 4 * 5 *****************************************************************************/ 6 7 /* 8 * Copyright (C) 2000 - 2012, 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 #include <linux/export.h> 45 #include <acpi/acpi.h> 46 #include "accommon.h" 47 48 #define _COMPONENT ACPI_HARDWARE 49 ACPI_MODULE_NAME("hwtimer") 50 51 #if (!ACPI_REDUCED_HARDWARE) /* Entire module */ 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 = 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 #endif /* !ACPI_REDUCED_HARDWARE */ 190