Revert "ARM: tegra: tegratab: dummy change"
[linux-2.6.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 - 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, &quotient, 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 */