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[karo-tx-linux.git] / drivers / acpi / acpica / hwtimer.c
1 /******************************************************************************
2  *
3  * Name: hwtimer.c - ACPI Power Management Timer Interface
4  *
5  *****************************************************************************/
6
7 /*
8  * Copyright (C) 2000 - 2013, Intel Corp.
9  * All rights reserved.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions, and the following disclaimer,
16  *    without modification.
17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
18  *    substantially similar to the "NO WARRANTY" disclaimer below
19  *    ("Disclaimer") and any redistribution must be conditioned upon
20  *    including a substantially similar Disclaimer requirement for further
21  *    binary redistribution.
22  * 3. Neither the names of the above-listed copyright holders nor the names
23  *    of any contributors may be used to endorse or promote products derived
24  *    from this software without specific prior written permission.
25  *
26  * Alternatively, this software may be distributed under the terms of the
27  * GNU General Public License ("GPL") version 2 as published by the Free
28  * Software Foundation.
29  *
30  * NO WARRANTY
31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
41  * POSSIBILITY OF SUCH DAMAGES.
42  */
43
44 #include <linux/export.h>
45 #include <acpi/acpi.h>
46 #include "accommon.h"
47
48 #define _COMPONENT          ACPI_HARDWARE
49 ACPI_MODULE_NAME("hwtimer")
50
51 #if (!ACPI_REDUCED_HARDWARE)    /* Entire module */
52 /******************************************************************************
53  *
54  * FUNCTION:    acpi_get_timer_resolution
55  *
56  * PARAMETERS:  resolution          - Where the resolution is returned
57  *
58  * RETURN:      Status and timer resolution
59  *
60  * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
61  *
62  ******************************************************************************/
63 acpi_status acpi_get_timer_resolution(u32 * resolution)
64 {
65         ACPI_FUNCTION_TRACE(acpi_get_timer_resolution);
66
67         if (!resolution) {
68                 return_ACPI_STATUS(AE_BAD_PARAMETER);
69         }
70
71         if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
72                 *resolution = 24;
73         } else {
74                 *resolution = 32;
75         }
76
77         return_ACPI_STATUS(AE_OK);
78 }
79
80 ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution)
81
82 /******************************************************************************
83  *
84  * FUNCTION:    acpi_get_timer
85  *
86  * PARAMETERS:  ticks               - Where the timer value is returned
87  *
88  * RETURN:      Status and current timer value (ticks)
89  *
90  * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
91  *
92  ******************************************************************************/
93 acpi_status acpi_get_timer(u32 * ticks)
94 {
95         acpi_status status;
96
97         ACPI_FUNCTION_TRACE(acpi_get_timer);
98
99         if (!ticks) {
100                 return_ACPI_STATUS(AE_BAD_PARAMETER);
101         }
102
103         status = 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         u64 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 (microseconds) =
180          *  (delta_ticks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY;
181          */
182         status = acpi_ut_short_divide(((u64)delta_ticks) * ACPI_USEC_PER_SEC,
183                                       ACPI_PM_TIMER_FREQUENCY, &quotient, NULL);
184
185         *time_elapsed = (u32) quotient;
186         return_ACPI_STATUS(status);
187 }
188
189 ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
190 #endif                          /* !ACPI_REDUCED_HARDWARE */