hwtimer.c revision 193335 
1
2/******************************************************************************
3 *
4 * Name: hwtimer.c - ACPI Power Management Timer Interface
5 *
6 *****************************************************************************/
7
8/******************************************************************************
9 *
10 * 1. Copyright Notice
11 *
12 * Some or all of this work - Copyright (c) 1999 - 2009, Intel Corp.
13 * All rights reserved.
14 *
15 * 2. License
16 *
17 * 2.1. This is your license from Intel Corp. under its intellectual property
18 * rights.  You may have additional license terms from the party that provided
19 * you this software, covering your right to use that party's intellectual
20 * property rights.
21 *
22 * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
23 * copy of the source code appearing in this file ("Covered Code") an
24 * irrevocable, perpetual, worldwide license under Intel's copyrights in the
25 * base code distributed originally by Intel ("Original Intel Code") to copy,
26 * make derivatives, distribute, use and display any portion of the Covered
27 * Code in any form, with the right to sublicense such rights; and
28 *
29 * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
30 * license (with the right to sublicense), under only those claims of Intel
31 * patents that are infringed by the Original Intel Code, to make, use, sell,
32 * offer to sell, and import the Covered Code and derivative works thereof
33 * solely to the minimum extent necessary to exercise the above copyright
34 * license, and in no event shall the patent license extend to any additions
35 * to or modifications of the Original Intel Code.  No other license or right
36 * is granted directly or by implication, estoppel or otherwise;
37 *
38 * The above copyright and patent license is granted only if the following
39 * conditions are met:
40 *
41 * 3. Conditions
42 *
43 * 3.1. Redistribution of Source with Rights to Further Distribute Source.
44 * Redistribution of source code of any substantial portion of the Covered
45 * Code or modification with rights to further distribute source must include
46 * the above Copyright Notice, the above License, this list of Conditions,
47 * and the following Disclaimer and Export Compliance provision.  In addition,
48 * Licensee must cause all Covered Code to which Licensee contributes to
49 * contain a file documenting the changes Licensee made to create that Covered
50 * Code and the date of any change.  Licensee must include in that file the
51 * documentation of any changes made by any predecessor Licensee.  Licensee
52 * must include a prominent statement that the modification is derived,
53 * directly or indirectly, from Original Intel Code.
54 *
55 * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
56 * Redistribution of source code of any substantial portion of the Covered
57 * Code or modification without rights to further distribute source must
58 * include the following Disclaimer and Export Compliance provision in the
59 * documentation and/or other materials provided with distribution.  In
60 * addition, Licensee may not authorize further sublicense of source of any
61 * portion of the Covered Code, and must include terms to the effect that the
62 * license from Licensee to its licensee is limited to the intellectual
63 * property embodied in the software Licensee provides to its licensee, and
64 * not to intellectual property embodied in modifications its licensee may
65 * make.
66 *
67 * 3.3. Redistribution of Executable. Redistribution in executable form of any
68 * substantial portion of the Covered Code or modification must reproduce the
69 * above Copyright Notice, and the following Disclaimer and Export Compliance
70 * provision in the documentation and/or other materials provided with the
71 * distribution.
72 *
73 * 3.4. Intel retains all right, title, and interest in and to the Original
74 * Intel Code.
75 *
76 * 3.5. Neither the name Intel nor any other trademark owned or controlled by
77 * Intel shall be used in advertising or otherwise to promote the sale, use or
78 * other dealings in products derived from or relating to the Covered Code
79 * without prior written authorization from Intel.
80 *
81 * 4. Disclaimer and Export Compliance
82 *
83 * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
84 * HERE.  ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
85 * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT,  ASSISTANCE,
86 * INSTALLATION, TRAINING OR OTHER SERVICES.  INTEL WILL NOT PROVIDE ANY
87 * UPDATES, ENHANCEMENTS OR EXTENSIONS.  INTEL SPECIFICALLY DISCLAIMS ANY
88 * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
89 * PARTICULAR PURPOSE.
90 *
91 * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
92 * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
93 * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
94 * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
95 * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
96 * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.  THESE LIMITATIONS
97 * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
98 * LIMITED REMEDY.
99 *
100 * 4.3. Licensee shall not export, either directly or indirectly, any of this
101 * software or system incorporating such software without first obtaining any
102 * required license or other approval from the U. S. Department of Commerce or
103 * any other agency or department of the United States Government.  In the
104 * event Licensee exports any such software from the United States or
105 * re-exports any such software from a foreign destination, Licensee shall
106 * ensure that the distribution and export/re-export of the software is in
107 * compliance with all laws, regulations, orders, or other restrictions of the
108 * U.S. Export Administration Regulations. Licensee agrees that neither it nor
109 * any of its subsidiaries will export/re-export any technical data, process,
110 * software, or service, directly or indirectly, to any country for which the
111 * United States government or any agency thereof requires an export license,
112 * other governmental approval, or letter of assurance, without first obtaining
113 * such license, approval or letter.
114 *
115 *****************************************************************************/
116
117#include "acpi.h"
118#include "accommon.h"
119
120#define _COMPONENT          ACPI_HARDWARE
121        ACPI_MODULE_NAME    ("hwtimer")
122
123
124/******************************************************************************
125 *
126 * FUNCTION:    AcpiGetTimerResolution
127 *
128 * PARAMETERS:  Resolution          - Where the resolution is returned
129 *
130 * RETURN:      Status and timer resolution
131 *
132 * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
133 *
134 ******************************************************************************/
135
136ACPI_STATUS
137AcpiGetTimerResolution (
138    UINT32                  *Resolution)
139{
140    ACPI_FUNCTION_TRACE (AcpiGetTimerResolution);
141
142
143    if (!Resolution)
144    {
145        return_ACPI_STATUS (AE_BAD_PARAMETER);
146    }
147
148    if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) == 0)
149    {
150        *Resolution = 24;
151    }
152    else
153    {
154        *Resolution = 32;
155    }
156
157    return_ACPI_STATUS (AE_OK);
158}
159
160ACPI_EXPORT_SYMBOL (AcpiGetTimerResolution)
161
162
163/******************************************************************************
164 *
165 * FUNCTION:    AcpiGetTimer
166 *
167 * PARAMETERS:  Ticks               - Where the timer value is returned
168 *
169 * RETURN:      Status and current timer value (ticks)
170 *
171 * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
172 *
173 ******************************************************************************/
174
175ACPI_STATUS
176AcpiGetTimer (
177    UINT32                  *Ticks)
178{
179    ACPI_STATUS             Status;
180
181
182    ACPI_FUNCTION_TRACE (AcpiGetTimer);
183
184
185    if (!Ticks)
186    {
187        return_ACPI_STATUS (AE_BAD_PARAMETER);
188    }
189
190    Status = AcpiRead (Ticks, &AcpiGbl_FADT.XPmTimerBlock);
191
192    return_ACPI_STATUS (Status);
193}
194
195ACPI_EXPORT_SYMBOL (AcpiGetTimer)
196
197
198/******************************************************************************
199 *
200 * FUNCTION:    AcpiGetTimerDuration
201 *
202 * PARAMETERS:  StartTicks          - Starting timestamp
203 *              EndTicks            - End timestamp
204 *              TimeElapsed         - Where the elapsed time is returned
205 *
206 * RETURN:      Status and TimeElapsed
207 *
208 * DESCRIPTION: Computes the time elapsed (in microseconds) between two
209 *              PM Timer time stamps, taking into account the possibility of
210 *              rollovers, the timer resolution, and timer frequency.
211 *
212 *              The PM Timer's clock ticks at roughly 3.6 times per
213 *              _microsecond_, and its clock continues through Cx state
214 *              transitions (unlike many CPU timestamp counters) -- making it
215 *              a versatile and accurate timer.
216 *
217 *              Note that this function accommodates only a single timer
218 *              rollover.  Thus for 24-bit timers, this function should only
219 *              be used for calculating durations less than ~4.6 seconds
220 *              (~20 minutes for 32-bit timers) -- calculations below:
221 *
222 *              2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
223 *              2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
224 *
225 ******************************************************************************/
226
227ACPI_STATUS
228AcpiGetTimerDuration (
229    UINT32                  StartTicks,
230    UINT32                  EndTicks,
231    UINT32                  *TimeElapsed)
232{
233    ACPI_STATUS             Status;
234    UINT32                  DeltaTicks;
235    ACPI_INTEGER            Quotient;
236
237
238    ACPI_FUNCTION_TRACE (AcpiGetTimerDuration);
239
240
241    if (!TimeElapsed)
242    {
243        return_ACPI_STATUS (AE_BAD_PARAMETER);
244    }
245
246    /*
247     * Compute Tick Delta:
248     * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
249     */
250    if (StartTicks < EndTicks)
251    {
252        DeltaTicks = EndTicks - StartTicks;
253    }
254    else if (StartTicks > EndTicks)
255    {
256        if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) == 0)
257        {
258            /* 24-bit Timer */
259
260            DeltaTicks = (((0x00FFFFFF - StartTicks) + EndTicks) & 0x00FFFFFF);
261        }
262        else
263        {
264            /* 32-bit Timer */
265
266            DeltaTicks = (0xFFFFFFFF - StartTicks) + EndTicks;
267        }
268    }
269    else /* StartTicks == EndTicks */
270    {
271        *TimeElapsed = 0;
272        return_ACPI_STATUS (AE_OK);
273    }
274
275    /*
276     * Compute Duration (Requires a 64-bit multiply and divide):
277     *
278     * TimeElapsed = (DeltaTicks * 1000000) / PM_TIMER_FREQUENCY;
279     */
280    Status = AcpiUtShortDivide (((UINT64) DeltaTicks) * 1000000,
281                PM_TIMER_FREQUENCY, &Quotient, NULL);
282
283    *TimeElapsed = (UINT32) Quotient;
284    return_ACPI_STATUS (Status);
285}
286
287ACPI_EXPORT_SYMBOL (AcpiGetTimerDuration)
288
289