ACPICA: Update all ACPICA copyrights and signons to 2010
[linux-3.10.git] / drivers / acpi / acpica / hwtimer.c
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         acpi_integer 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, &quotient, NULL);
183
184         *time_elapsed = (u32) quotient;
185         return_ACPI_STATUS(status);
186 }
187
188 ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)