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 /******************************************************************************
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 ******************************************************************************/
acpi_get_timer_resolution(u32 * resolution)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
ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution)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 =
104 acpi_hw_read(ticks, &acpi_gbl_FADT.xpm_timer_block);
105
106 return_ACPI_STATUS(status);
107 }
108
ACPI_EXPORT_SYMBOL(acpi_get_timer)109 ACPI_EXPORT_SYMBOL(acpi_get_timer)
110
111 /******************************************************************************
112 *
113 * FUNCTION: acpi_get_timer_duration
114 *
115 * PARAMETERS: start_ticks - Starting timestamp
116 * end_ticks - End timestamp
117 * time_elapsed - Where the elapsed time is returned
118 *
119 * RETURN: Status and time_elapsed
120 *
121 * DESCRIPTION: Computes the time elapsed (in microseconds) between two
122 * PM Timer time stamps, taking into account the possibility of
123 * rollovers, the timer resolution, and timer frequency.
124 *
125 * The PM Timer's clock ticks at roughly 3.6 times per
126 * _microsecond_, and its clock continues through Cx state
127 * transitions (unlike many CPU timestamp counters) -- making it
128 * a versatile and accurate timer.
129 *
130 * Note that this function accommodates only a single timer
131 * rollover. Thus for 24-bit timers, this function should only
132 * be used for calculating durations less than ~4.6 seconds
133 * (~20 minutes for 32-bit timers) -- calculations below:
134 *
135 * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
136 * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
137 *
138 ******************************************************************************/
139 acpi_status
140 acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 * time_elapsed)
141 {
142 acpi_status status;
143 u32 delta_ticks;
144 u64 quotient;
145
146 ACPI_FUNCTION_TRACE(acpi_get_timer_duration);
147
148 if (!time_elapsed) {
149 return_ACPI_STATUS(AE_BAD_PARAMETER);
150 }
151
152 /*
153 * Compute Tick Delta:
154 * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
155 */
156 if (start_ticks < end_ticks) {
157 delta_ticks = end_ticks - start_ticks;
158 } else if (start_ticks > end_ticks) {
159 if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
160
161 /* 24-bit Timer */
162
163 delta_ticks =
164 (((0x00FFFFFF - start_ticks) +
165 end_ticks) & 0x00FFFFFF);
166 } else {
167 /* 32-bit Timer */
168
169 delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks;
170 }
171 } else { /* start_ticks == end_ticks */
172
173 *time_elapsed = 0;
174 return_ACPI_STATUS(AE_OK);
175 }
176
177 /*
178 * Compute Duration (Requires a 64-bit multiply and divide):
179 *
180 * time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY;
181 */
182 status = acpi_ut_short_divide(((u64) delta_ticks) * 1000000,
183 PM_TIMER_FREQUENCY, "ient, NULL);
184
185 *time_elapsed = (u32) quotient;
186 return_ACPI_STATUS(status);
187 }
188
189 ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
190