Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux...
[linux-2.6] / drivers / acpi / hardware / hwtimer.c
1
2 /******************************************************************************
3  *
4  * Name: hwtimer.c - ACPI Power Management Timer Interface
5  *
6  *****************************************************************************/
7
8 /*
9  * Copyright (C) 2000 - 2007, 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 <acpi/acpi.h>
46
47 #define _COMPONENT          ACPI_HARDWARE
48 ACPI_MODULE_NAME("hwtimer")
49
50 /******************************************************************************
51  *
52  * FUNCTION:    acpi_get_timer_resolution
53  *
54  * PARAMETERS:  Resolution          - Where the resolution is returned
55  *
56  * RETURN:      Status and timer resolution
57  *
58  * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
59  *
60  ******************************************************************************/
61 acpi_status acpi_get_timer_resolution(u32 * resolution)
62 {
63         ACPI_FUNCTION_TRACE(acpi_get_timer_resolution);
64
65         if (!resolution) {
66                 return_ACPI_STATUS(AE_BAD_PARAMETER);
67         }
68
69         if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
70                 *resolution = 24;
71         } else {
72                 *resolution = 32;
73         }
74
75         return_ACPI_STATUS(AE_OK);
76 }
77
78 ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution)
79
80 /******************************************************************************
81  *
82  * FUNCTION:    acpi_get_timer
83  *
84  * PARAMETERS:  Ticks               - Where the timer value is returned
85  *
86  * RETURN:      Status and current timer value (ticks)
87  *
88  * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
89  *
90  ******************************************************************************/
91 acpi_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 =
102             acpi_hw_low_level_read(32, ticks, &acpi_gbl_FADT.xpm_timer_block);
103
104         return_ACPI_STATUS(status);
105 }
106
107 ACPI_EXPORT_SYMBOL(acpi_get_timer)
108
109 /******************************************************************************
110  *
111  * FUNCTION:    acpi_get_timer_duration
112  *
113  * PARAMETERS:  start_ticks         - Starting timestamp
114  *              end_ticks           - End timestamp
115  *              time_elapsed        - Where the elapsed time is returned
116  *
117  * RETURN:      Status and time_elapsed
118  *
119  * DESCRIPTION: Computes the time elapsed (in microseconds) between two
120  *              PM Timer time stamps, taking into account the possibility of
121  *              rollovers, the timer resolution, and timer frequency.
122  *
123  *              The PM Timer's clock ticks at roughly 3.6 times per
124  *              _microsecond_, and its clock continues through Cx state
125  *              transitions (unlike many CPU timestamp counters) -- making it
126  *              a versatile and accurate timer.
127  *
128  *              Note that this function accommodates only a single timer
129  *              rollover.  Thus for 24-bit timers, this function should only
130  *              be used for calculating durations less than ~4.6 seconds
131  *              (~20 minutes for 32-bit timers) -- calculations below:
132  *
133  *              2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
134  *              2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
135  *
136  ******************************************************************************/
137 acpi_status
138 acpi_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 ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
158
159                         /* 24-bit Timer */
160
161                         delta_ticks =
162                             (((0x00FFFFFF - start_ticks) +
163                               end_ticks) & 0x00FFFFFF);
164                 } else {
165                         /* 32-bit Timer */
166
167                         delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks;
168                 }
169         } else {                /* start_ticks == end_ticks */
170
171                 *time_elapsed = 0;
172                 return_ACPI_STATUS(AE_OK);
173         }
174
175         /*
176          * Compute Duration (Requires a 64-bit multiply and divide):
177          *
178          * time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY;
179          */
180         status = acpi_ut_short_divide(((u64) delta_ticks) * 1000000,
181                                       PM_TIMER_FREQUENCY, &quotient, NULL);
182
183         *time_elapsed = (u32) quotient;
184         return_ACPI_STATUS(status);
185 }
186
187 ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)