1
2 /******************************************************************************
3 *
4 * Name: hwtimer.c - ACPI Power Management Timer Interface
5 *
6 *****************************************************************************/
7
8 /*
9 * Copyright (C) 2000 - 2004, 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 *
53 * FUNCTION: acpi_get_timer_resolution
54 *
55 * PARAMETERS: none
56 *
57 * RETURN: Number of bits of resolution in the PM Timer (24 or 32).
58 *
59 * DESCRIPTION: Obtains resolution of the ACPI PM Timer.
60 *
61 ******************************************************************************/
62
63 acpi_status
acpi_get_timer_resolution(u32 * resolution)64 acpi_get_timer_resolution (
65 u32 *resolution)
66 {
67 ACPI_FUNCTION_TRACE ("acpi_get_timer_resolution");
68
69
70 if (!resolution) {
71 return_ACPI_STATUS (AE_BAD_PARAMETER);
72 }
73
74 if (0 == acpi_gbl_FADT->tmr_val_ext) {
75 *resolution = 24;
76 }
77 else {
78 *resolution = 32;
79 }
80
81 return_ACPI_STATUS (AE_OK);
82 }
83
84
85 /******************************************************************************
86 *
87 * FUNCTION: acpi_get_timer
88 *
89 * PARAMETERS: none
90 *
91 * RETURN: Current value of the ACPI PM Timer (in ticks).
92 *
93 * DESCRIPTION: Obtains current value of ACPI PM Timer.
94 *
95 ******************************************************************************/
96
97 acpi_status
acpi_get_timer(u32 * ticks)98 acpi_get_timer (
99 u32 *ticks)
100 {
101 acpi_status status;
102
103
104 ACPI_FUNCTION_TRACE ("acpi_get_timer");
105
106
107 if (!ticks) {
108 return_ACPI_STATUS (AE_BAD_PARAMETER);
109 }
110
111 status = acpi_hw_low_level_read (32, ticks, &acpi_gbl_FADT->xpm_tmr_blk);
112
113 return_ACPI_STATUS (status);
114 }
115
116
117 /******************************************************************************
118 *
119 * FUNCTION: acpi_get_timer_duration
120 *
121 * PARAMETERS: start_ticks
122 * end_ticks
123 * time_elapsed
124 *
125 * RETURN: time_elapsed
126 *
127 * DESCRIPTION: Computes the time elapsed (in microseconds) between two
128 * PM Timer time stamps, taking into account the possibility of
129 * rollovers, the timer resolution, and timer frequency.
130 *
131 * The PM Timer's clock ticks at roughly 3.6 times per
132 * _microsecond_, and its clock continues through Cx state
133 * transitions (unlike many CPU timestamp counters) -- making it
134 * a versatile and accurate timer.
135 *
136 * Note that this function accommodates only a single timer
137 * rollover. Thus for 24-bit timers, this function should only
138 * be used for calculating durations less than ~4.6 seconds
139 * (~20 minutes for 32-bit timers) -- calculations below
140 *
141 * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
142 * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
143 *
144 ******************************************************************************/
145
146 acpi_status
acpi_get_timer_duration(u32 start_ticks,u32 end_ticks,u32 * time_elapsed)147 acpi_get_timer_duration (
148 u32 start_ticks,
149 u32 end_ticks,
150 u32 *time_elapsed)
151 {
152 u32 delta_ticks = 0;
153 union uint64_overlay normalized_ticks;
154 acpi_status status;
155 acpi_integer out_quotient;
156
157
158 ACPI_FUNCTION_TRACE ("acpi_get_timer_duration");
159
160
161 if (!time_elapsed) {
162 return_ACPI_STATUS (AE_BAD_PARAMETER);
163 }
164
165 /*
166 * Compute Tick Delta:
167 * -------------------
168 * Handle (max one) timer rollovers on 24- versus 32-bit timers.
169 */
170 if (start_ticks < end_ticks) {
171 delta_ticks = end_ticks - start_ticks;
172 }
173 else if (start_ticks > end_ticks) {
174 if (0 == acpi_gbl_FADT->tmr_val_ext) {
175 /* 24-bit Timer */
176
177 delta_ticks = (((0x00FFFFFF - start_ticks) + end_ticks) & 0x00FFFFFF);
178 }
179 else {
180 /* 32-bit Timer */
181
182 delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks;
183 }
184 }
185 else {
186 *time_elapsed = 0;
187 return_ACPI_STATUS (AE_OK);
188 }
189
190 /*
191 * Compute Duration:
192 * -----------------
193 *
194 * Requires a 64-bit divide:
195 *
196 * time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY;
197 */
198 normalized_ticks.full = ((u64) delta_ticks) * 1000000;
199
200 status = acpi_ut_short_divide (&normalized_ticks.full, PM_TIMER_FREQUENCY,
201 &out_quotient, NULL);
202
203 *time_elapsed = (u32) out_quotient;
204 return_ACPI_STATUS (status);
205 }
206
207
208