1 2 /****************************************************************************** 3 * 4 * Name: hwtimer.c - ACPI Power Management Timer Interface 5 * 6 *****************************************************************************/ 7 8 /* 9 * Copyright (C) 2000 - 2012, 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 #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 status = 105 acpi_hw_read(ticks, &acpi_gbl_FADT.xpm_timer_block); 106 107 return_ACPI_STATUS(status); 108 } 109 110 ACPI_EXPORT_SYMBOL(acpi_get_timer) 111 112 /****************************************************************************** 113 * 114 * FUNCTION: acpi_get_timer_duration 115 * 116 * PARAMETERS: start_ticks - Starting timestamp 117 * end_ticks - End timestamp 118 * time_elapsed - Where the elapsed time is returned 119 * 120 * RETURN: Status and time_elapsed 121 * 122 * DESCRIPTION: Computes the time elapsed (in microseconds) between two 123 * PM Timer time stamps, taking into account the possibility of 124 * rollovers, the timer resolution, and timer frequency. 125 * 126 * The PM Timer's clock ticks at roughly 3.6 times per 127 * _microsecond_, and its clock continues through Cx state 128 * transitions (unlike many CPU timestamp counters) -- making it 129 * a versatile and accurate timer. 130 * 131 * Note that this function accommodates only a single timer 132 * rollover. Thus for 24-bit timers, this function should only 133 * be used for calculating durations less than ~4.6 seconds 134 * (~20 minutes for 32-bit timers) -- calculations below: 135 * 136 * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec 137 * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes 138 * 139 ******************************************************************************/ 140 acpi_status 141 acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 * time_elapsed) 142 { 143 acpi_status status; 144 u32 delta_ticks; 145 u64 quotient; 146 147 ACPI_FUNCTION_TRACE(acpi_get_timer_duration); 148 149 if (!time_elapsed) { 150 return_ACPI_STATUS(AE_BAD_PARAMETER); 151 } 152 153 /* 154 * Compute Tick Delta: 155 * Handle (max one) timer rollovers on 24-bit versus 32-bit timers. 156 */ 157 if (start_ticks < end_ticks) { 158 delta_ticks = end_ticks - start_ticks; 159 } else if (start_ticks > end_ticks) { 160 if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) { 161 162 /* 24-bit Timer */ 163 164 delta_ticks = 165 (((0x00FFFFFF - start_ticks) + 166 end_ticks) & 0x00FFFFFF); 167 } else { 168 /* 32-bit Timer */ 169 170 delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks; 171 } 172 } else { /* start_ticks == end_ticks */ 173 174 *time_elapsed = 0; 175 return_ACPI_STATUS(AE_OK); 176 } 177 178 /* 179 * Compute Duration (Requires a 64-bit multiply and divide): 180 * 181 * time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY; 182 */ 183 status = acpi_ut_short_divide(((u64) delta_ticks) * 1000000, 184 PM_TIMER_FREQUENCY, "ient, NULL); 185 186 *time_elapsed = (u32) quotient; 187 return_ACPI_STATUS(status); 188 } 189 190 ACPI_EXPORT_SYMBOL(acpi_get_timer_duration) 191 #endif /* !ACPI_REDUCED_HARDWARE */ 192