1
2 /******************************************************************************
3 *
4 * Name: hwtimer.c - ACPI Power Management Timer Interface
5 *
6 *****************************************************************************/
7
8 /*
9 * Copyright (C) 2000 - 2011, 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 "acpi.h"
46 #include "accommon.h"
47
48 #define _COMPONENT ACPI_HARDWARE
49 ACPI_MODULE_NAME ("hwtimer")
50
51
52 /******************************************************************************
53 *
54 * FUNCTION: AcpiGetTimerResolution
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
64 ACPI_STATUS
65 AcpiGetTimerResolution (
66 UINT32 *Resolution)
67 {
68 ACPI_FUNCTION_TRACE (AcpiGetTimerResolution);
69
70
71 if (!Resolution)
72 {
73 return_ACPI_STATUS (AE_BAD_PARAMETER);
74 }
75
76 if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) == 0)
77 {
78 *Resolution = 24;
79 }
80 else
81 {
82 *Resolution = 32;
83 }
84
85 return_ACPI_STATUS (AE_OK);
86 }
87
88 ACPI_EXPORT_SYMBOL (AcpiGetTimerResolution)
89
90
91 /******************************************************************************
92 *
93 * FUNCTION: AcpiGetTimer
94 *
95 * PARAMETERS: Ticks - Where the timer value is returned
96 *
97 * RETURN: Status and current timer value (ticks)
98 *
99 * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
100 *
101 ******************************************************************************/
102
103 ACPI_STATUS
104 AcpiGetTimer (
105 UINT32 *Ticks)
106 {
107 ACPI_STATUS Status;
108
109
110 ACPI_FUNCTION_TRACE (AcpiGetTimer);
111
112
113 if (!Ticks)
114 {
115 return_ACPI_STATUS (AE_BAD_PARAMETER);
116 }
117
118 Status = AcpiHwRead (Ticks, &AcpiGbl_FADT.XPmTimerBlock);
119
120 return_ACPI_STATUS (Status);
121 }
122
123 ACPI_EXPORT_SYMBOL (AcpiGetTimer)
124
125
126 /******************************************************************************
127 *
128 * FUNCTION: AcpiGetTimerDuration
129 *
130 * PARAMETERS: StartTicks - Starting timestamp
131 * EndTicks - End timestamp
132 * TimeElapsed - Where the elapsed time is returned
133 *
134 * RETURN: Status and TimeElapsed
135 *
136 * DESCRIPTION: Computes the time elapsed (in microseconds) between two
137 * PM Timer time stamps, taking into account the possibility of
138 * rollovers, the timer resolution, and timer frequency.
139 *
140 * The PM Timer's clock ticks at roughly 3.6 times per
141 * _microsecond_, and its clock continues through Cx state
142 * transitions (unlike many CPU timestamp counters) -- making it
143 * a versatile and accurate timer.
144 *
145 * Note that this function accommodates only a single timer
146 * rollover. Thus for 24-bit timers, this function should only
147 * be used for calculating durations less than ~4.6 seconds
148 * (~20 minutes for 32-bit timers) -- calculations below:
149 *
150 * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
151 * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
152 *
153 ******************************************************************************/
154
155 ACPI_STATUS
156 AcpiGetTimerDuration (
157 UINT32 StartTicks,
158 UINT32 EndTicks,
159 UINT32 *TimeElapsed)
160 {
161 ACPI_STATUS Status;
162 UINT32 DeltaTicks;
163 UINT64 Quotient;
164
165
166 ACPI_FUNCTION_TRACE (AcpiGetTimerDuration);
167
168
169 if (!TimeElapsed)
170 {
171 return_ACPI_STATUS (AE_BAD_PARAMETER);
172 }
173
174 /*
175 * Compute Tick Delta:
176 * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
177 */
178 if (StartTicks < EndTicks)
179 {
180 DeltaTicks = EndTicks - StartTicks;
181 }
182 else if (StartTicks > EndTicks)
183 {
184 if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) == 0)
185 {
186 /* 24-bit Timer */
187
188 DeltaTicks = (((0x00FFFFFF - StartTicks) + EndTicks) & 0x00FFFFFF);
189 }
190 else
191 {
192 /* 32-bit Timer */
193
194 DeltaTicks = (0xFFFFFFFF - StartTicks) + EndTicks;
195 }
196 }
197 else /* StartTicks == EndTicks */
198 {
199 *TimeElapsed = 0;
200 return_ACPI_STATUS (AE_OK);
201 }
202
203 /*
204 * Compute Duration (Requires a 64-bit multiply and divide):
205 *
206 * TimeElapsed = (DeltaTicks * 1000000) / PM_TIMER_FREQUENCY;
207 */
208 Status = AcpiUtShortDivide (((UINT64) DeltaTicks) * 1000000,
209 PM_TIMER_FREQUENCY, &Quotient, NULL);
210
211 *TimeElapsed = (UINT32) Quotient;
212 return_ACPI_STATUS (Status);
213 }
214
215 ACPI_EXPORT_SYMBOL (AcpiGetTimerDuration)
216