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Linux kernel mirror (for testing)
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1
2/******************************************************************************
3 *
4 * Name: hwtimer.c - ACPI Power Management Timer Interface
5 *
6 *****************************************************************************/
7
8/*
9 * Copyright (C) 2000 - 2005, 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 <linux/module.h>
46#include <acpi/acpi.h>
47
48#define _COMPONENT ACPI_HARDWARE
49ACPI_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 ******************************************************************************/
62acpi_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 (0 == acpi_gbl_FADT->tmr_val_ext) {
71 *resolution = 24;
72 } else {
73 *resolution = 32;
74 }
75
76 return_ACPI_STATUS(AE_OK);
77}
78
79/******************************************************************************
80 *
81 * FUNCTION: acpi_get_timer
82 *
83 * PARAMETERS: Ticks - Where the timer value is returned
84 *
85 * RETURN: Status and current timer value (ticks)
86 *
87 * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
88 *
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 = acpi_hw_low_level_read(32, ticks, &acpi_gbl_FADT->xpm_tmr_blk);
102
103 return_ACPI_STATUS(status);
104}
105
106EXPORT_SYMBOL(acpi_get_timer);
107
108/******************************************************************************
109 *
110 * FUNCTION: acpi_get_timer_duration
111 *
112 * PARAMETERS: start_ticks - Starting timestamp
113 * end_ticks - End timestamp
114 * time_elapsed - Where the elapsed time is returned
115 *
116 * RETURN: Status and time_elapsed
117 *
118 * DESCRIPTION: Computes the time elapsed (in microseconds) between two
119 * PM Timer time stamps, taking into account the possibility of
120 * rollovers, the timer resolution, and timer frequency.
121 *
122 * The PM Timer's clock ticks at roughly 3.6 times per
123 * _microsecond_, and its clock continues through Cx state
124 * transitions (unlike many CPU timestamp counters) -- making it
125 * a versatile and accurate timer.
126 *
127 * Note that this function accommodates only a single timer
128 * rollover. Thus for 24-bit timers, this function should only
129 * be used for calculating durations less than ~4.6 seconds
130 * (~20 minutes for 32-bit timers) -- calculations below:
131 *
132 * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
133 * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
134 *
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 (0 == acpi_gbl_FADT->tmr_val_ext) {
158 /* 24-bit Timer */
159
160 delta_ticks =
161 (((0x00FFFFFF - start_ticks) +
162 end_ticks) & 0x00FFFFFF);
163 } else {
164 /* 32-bit Timer */
165
166 delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks;
167 }
168 } else { /* start_ticks == end_ticks */
169
170 *time_elapsed = 0;
171 return_ACPI_STATUS(AE_OK);
172 }
173
174 /*
175 * Compute Duration (Requires a 64-bit multiply and divide):
176 *
177 * time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY;
178 */
179 status = acpi_ut_short_divide(((u64) delta_ticks) * 1000000,
180 PM_TIMER_FREQUENCY, "ient, NULL);
181
182 *time_elapsed = (u32) quotient;
183 return_ACPI_STATUS(status);
184}
185
186EXPORT_SYMBOL(acpi_get_timer_duration);