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1da177e4 LT |
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 | ||
47 | #include <acpi/acpi.h> | |
48 | ||
49 | #define _COMPONENT ACPI_HARDWARE | |
50 | ACPI_MODULE_NAME ("hwtimer") | |
51 | ||
52 | ||
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 | ||
65 | acpi_status | |
66 | acpi_get_timer_resolution ( | |
67 | u32 *resolution) | |
68 | { | |
69 | ACPI_FUNCTION_TRACE ("acpi_get_timer_resolution"); | |
70 | ||
71 | ||
72 | if (!resolution) { | |
73 | return_ACPI_STATUS (AE_BAD_PARAMETER); | |
74 | } | |
75 | ||
76 | if (0 == acpi_gbl_FADT->tmr_val_ext) { | |
77 | *resolution = 24; | |
78 | } | |
79 | else { | |
80 | *resolution = 32; | |
81 | } | |
82 | ||
83 | return_ACPI_STATUS (AE_OK); | |
84 | } | |
85 | ||
86 | ||
87 | /****************************************************************************** | |
88 | * | |
89 | * FUNCTION: acpi_get_timer | |
90 | * | |
91 | * PARAMETERS: Ticks - Where the timer value is returned | |
92 | * | |
93 | * RETURN: Status and current ticks | |
94 | * | |
95 | * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks). | |
96 | * | |
97 | ******************************************************************************/ | |
98 | ||
99 | acpi_status | |
100 | acpi_get_timer ( | |
101 | u32 *ticks) | |
102 | { | |
103 | acpi_status status; | |
104 | ||
105 | ||
106 | ACPI_FUNCTION_TRACE ("acpi_get_timer"); | |
107 | ||
108 | ||
109 | if (!ticks) { | |
110 | return_ACPI_STATUS (AE_BAD_PARAMETER); | |
111 | } | |
112 | ||
113 | status = acpi_hw_low_level_read (32, ticks, &acpi_gbl_FADT->xpm_tmr_blk); | |
114 | ||
115 | return_ACPI_STATUS (status); | |
116 | } | |
117 | EXPORT_SYMBOL(acpi_get_timer); | |
118 | ||
119 | ||
120 | /****************************************************************************** | |
121 | * | |
122 | * FUNCTION: acpi_get_timer_duration | |
123 | * | |
124 | * PARAMETERS: start_ticks - Starting timestamp | |
125 | * end_ticks - End timestamp | |
126 | * time_elapsed - Where the elapsed time is returned | |
127 | * | |
128 | * RETURN: Status and time_elapsed | |
129 | * | |
130 | * DESCRIPTION: Computes the time elapsed (in microseconds) between two | |
131 | * PM Timer time stamps, taking into account the possibility of | |
132 | * rollovers, the timer resolution, and timer frequency. | |
133 | * | |
134 | * The PM Timer's clock ticks at roughly 3.6 times per | |
135 | * _microsecond_, and its clock continues through Cx state | |
136 | * transitions (unlike many CPU timestamp counters) -- making it | |
137 | * a versatile and accurate timer. | |
138 | * | |
139 | * Note that this function accommodates only a single timer | |
140 | * rollover. Thus for 24-bit timers, this function should only | |
141 | * be used for calculating durations less than ~4.6 seconds | |
142 | * (~20 minutes for 32-bit timers) -- calculations below: | |
143 | * | |
144 | * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec | |
145 | * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes | |
146 | * | |
147 | ******************************************************************************/ | |
148 | ||
149 | acpi_status | |
150 | acpi_get_timer_duration ( | |
151 | u32 start_ticks, | |
152 | u32 end_ticks, | |
153 | u32 *time_elapsed) | |
154 | { | |
155 | acpi_status status; | |
156 | u32 delta_ticks; | |
157 | acpi_integer quotient; | |
158 | ||
159 | ||
160 | ACPI_FUNCTION_TRACE ("acpi_get_timer_duration"); | |
161 | ||
162 | ||
163 | if (!time_elapsed) { | |
164 | return_ACPI_STATUS (AE_BAD_PARAMETER); | |
165 | } | |
166 | ||
167 | /* | |
168 | * Compute Tick Delta: | |
169 | * Handle (max one) timer rollovers on 24-bit versus 32-bit timers. | |
170 | */ | |
171 | if (start_ticks < end_ticks) { | |
172 | delta_ticks = end_ticks - start_ticks; | |
173 | } | |
174 | else if (start_ticks > end_ticks) { | |
175 | if (0 == acpi_gbl_FADT->tmr_val_ext) { | |
176 | /* 24-bit Timer */ | |
177 | ||
178 | delta_ticks = (((0x00FFFFFF - start_ticks) + end_ticks) & 0x00FFFFFF); | |
179 | } | |
180 | else { | |
181 | /* 32-bit Timer */ | |
182 | ||
183 | delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks; | |
184 | } | |
185 | } | |
186 | else /* start_ticks == end_ticks */ { | |
187 | *time_elapsed = 0; | |
188 | return_ACPI_STATUS (AE_OK); | |
189 | } | |
190 | ||
191 | /* | |
192 | * Compute Duration (Requires a 64-bit multiply and divide): | |
193 | * | |
194 | * time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY; | |
195 | */ | |
196 | status = acpi_ut_short_divide (((u64) delta_ticks) * 1000000, | |
197 | PM_TIMER_FREQUENCY, "ient, NULL); | |
198 | ||
199 | *time_elapsed = (u32) quotient; | |
200 | return_ACPI_STATUS (status); | |
201 | } | |
202 | EXPORT_SYMBOL(acpi_get_timer_duration); | |
203 |