hwtimer.c revision 73561 
1
2/******************************************************************************
3 *
4 * Name: hwtimer.c - ACPI Power Management Timer Interface
5 *              $Revision: 5 $
6 *
7 *****************************************************************************/
8
9/******************************************************************************
10 *
11 * 1. Copyright Notice
12 *
13 * Some or all of this work - Copyright (c) 1999, 2000, 2001, Intel Corp.
14 * All rights reserved.
15 *
16 * 2. License
17 *
18 * 2.1. This is your license from Intel Corp. under its intellectual property
19 * rights.  You may have additional license terms from the party that provided
20 * you this software, covering your right to use that party's intellectual
21 * property rights.
22 *
23 * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
24 * copy of the source code appearing in this file ("Covered Code") an
25 * irrevocable, perpetual, worldwide license under Intel's copyrights in the
26 * base code distributed originally by Intel ("Original Intel Code") to copy,
27 * make derivatives, distribute, use and display any portion of the Covered
28 * Code in any form, with the right to sublicense such rights; and
29 *
30 * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
31 * license (with the right to sublicense), under only those claims of Intel
32 * patents that are infringed by the Original Intel Code, to make, use, sell,
33 * offer to sell, and import the Covered Code and derivative works thereof
34 * solely to the minimum extent necessary to exercise the above copyright
35 * license, and in no event shall the patent license extend to any additions
36 * to or modifications of the Original Intel Code.  No other license or right
37 * is granted directly or by implication, estoppel or otherwise;
38 *
39 * The above copyright and patent license is granted only if the following
40 * conditions are met:
41 *
42 * 3. Conditions
43 *
44 * 3.1. Redistribution of Source with Rights to Further Distribute Source.
45 * Redistribution of source code of any substantial portion of the Covered
46 * Code or modification with rights to further distribute source must include
47 * the above Copyright Notice, the above License, this list of Conditions,
48 * and the following Disclaimer and Export Compliance provision.  In addition,
49 * Licensee must cause all Covered Code to which Licensee contributes to
50 * contain a file documenting the changes Licensee made to create that Covered
51 * Code and the date of any change.  Licensee must include in that file the
52 * documentation of any changes made by any predecessor Licensee.  Licensee
53 * must include a prominent statement that the modification is derived,
54 * directly or indirectly, from Original Intel Code.
55 *
56 * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
57 * Redistribution of source code of any substantial portion of the Covered
58 * Code or modification without rights to further distribute source must
59 * include the following Disclaimer and Export Compliance provision in the
60 * documentation and/or other materials provided with distribution.  In
61 * addition, Licensee may not authorize further sublicense of source of any
62 * portion of the Covered Code, and must include terms to the effect that the
63 * license from Licensee to its licensee is limited to the intellectual
64 * property embodied in the software Licensee provides to its licensee, and
65 * not to intellectual property embodied in modifications its licensee may
66 * make.
67 *
68 * 3.3. Redistribution of Executable. Redistribution in executable form of any
69 * substantial portion of the Covered Code or modification must reproduce the
70 * above Copyright Notice, and the following Disclaimer and Export Compliance
71 * provision in the documentation and/or other materials provided with the
72 * distribution.
73 *
74 * 3.4. Intel retains all right, title, and interest in and to the Original
75 * Intel Code.
76 *
77 * 3.5. Neither the name Intel nor any other trademark owned or controlled by
78 * Intel shall be used in advertising or otherwise to promote the sale, use or
79 * other dealings in products derived from or relating to the Covered Code
80 * without prior written authorization from Intel.
81 *
82 * 4. Disclaimer and Export Compliance
83 *
84 * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
85 * HERE.  ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
86 * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT,  ASSISTANCE,
87 * INSTALLATION, TRAINING OR OTHER SERVICES.  INTEL WILL NOT PROVIDE ANY
88 * UPDATES, ENHANCEMENTS OR EXTENSIONS.  INTEL SPECIFICALLY DISCLAIMS ANY
89 * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
90 * PARTICULAR PURPOSE.
91 *
92 * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
93 * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
94 * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
95 * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
96 * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
97 * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.  THESE LIMITATIONS
98 * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
99 * LIMITED REMEDY.
100 *
101 * 4.3. Licensee shall not export, either directly or indirectly, any of this
102 * software or system incorporating such software without first obtaining any
103 * required license or other approval from the U. S. Department of Commerce or
104 * any other agency or department of the United States Government.  In the
105 * event Licensee exports any such software from the United States or
106 * re-exports any such software from a foreign destination, Licensee shall
107 * ensure that the distribution and export/re-export of the software is in
108 * compliance with all laws, regulations, orders, or other restrictions of the
109 * U.S. Export Administration Regulations. Licensee agrees that neither it nor
110 * any of its subsidiaries will export/re-export any technical data, process,
111 * software, or service, directly or indirectly, to any country for which the
112 * United States government or any agency thereof requires an export license,
113 * other governmental approval, or letter of assurance, without first obtaining
114 * such license, approval or letter.
115 *
116 *****************************************************************************/
117
118#include "acpi.h"
119#include "achware.h"
120
121#define _COMPONENT          HARDWARE
122        MODULE_NAME         ("hwtimer")
123
124
125/******************************************************************************
126 *
127 * FUNCTION:    AcpiGetTimerResolution
128 *
129 * PARAMETERS:  none
130 *
131 * RETURN:      Number of bits of resolution in the PM Timer (24 or 32).
132 *
133 * DESCRIPTION: Obtains resolution of the ACPI PM Timer.
134 *
135 ******************************************************************************/
136
137ACPI_STATUS
138AcpiGetTimerResolution (
139    UINT32                  *Resolution)
140{
141    FUNCTION_TRACE ("AcpiGetTimerResolution");
142
143    if (!Resolution)
144    {
145        return_ACPI_STATUS (AE_BAD_PARAMETER);
146    }
147
148    if (0 == AcpiGbl_FADT->TmrValExt)
149    {
150        *Resolution = 24;
151    }
152    else
153    {
154        *Resolution = 32;
155    }
156
157    return_ACPI_STATUS (AE_OK);
158}
159
160
161/******************************************************************************
162 *
163 * FUNCTION:    AcpiGetTimer
164 *
165 * PARAMETERS:  none
166 *
167 * RETURN:      Current value of the ACPI PM Timer (in ticks).
168 *
169 * DESCRIPTION: Obtains current value of ACPI PM Timer.
170 *
171 ******************************************************************************/
172
173ACPI_STATUS
174AcpiGetTimer (
175    UINT32                  *Ticks)
176{
177    FUNCTION_TRACE ("AcpiGetTimer");
178
179    if (!Ticks)
180    {
181        return_ACPI_STATUS (AE_BAD_PARAMETER);
182    }
183
184    *Ticks = AcpiOsIn32 ((ACPI_IO_ADDRESS) ACPI_GET_ADDRESS (AcpiGbl_FADT->XPmTmrBlk.Address));
185
186    return_ACPI_STATUS (AE_OK);
187}
188
189
190/******************************************************************************
191 *
192 * FUNCTION:    AcpiGetTimerDuration
193 *
194 * PARAMETERS:  StartTicks
195 *              EndTicks
196 *              TimeElapsed
197 *
198 * RETURN:      TimeElapsed
199 *
200 * DESCRIPTION: Computes the time elapsed (in microseconds) between two
201 *              PM Timer time stamps, taking into account the possibility of
202 *              rollovers, the timer resolution, and timer frequency.
203 *
204 *              The PM Timer's clock ticks at roughly 3.6 times per
205 *              _microsecond_, and its clock continues through Cx state
206 *              transitions (unlike many CPU timestamp counters) -- making it
207 *              a versatile and accurate timer.
208 *
209 *              Note that this function accomodates only a single timer
210 *              rollover.  Thus for 24-bit timers, this function should only
211 *              be used for calculating durations less than ~4.6 seconds
212 *              (~20 hours for 32-bit timers).
213 *
214 ******************************************************************************/
215
216ACPI_STATUS
217AcpiGetTimerDuration (
218    UINT32                  StartTicks,
219    UINT32                  EndTicks,
220    UINT32                  *TimeElapsed)
221{
222    UINT32                  DeltaTicks = 0;
223    UINT32                  Seconds = 0;
224    UINT32                  Milliseconds = 0;
225    UINT32                  Microseconds = 0;
226    UINT32                  Remainder = 0;
227
228    FUNCTION_TRACE ("AcpiGetTimerDuration");
229
230    if (!TimeElapsed)
231    {
232        return_ACPI_STATUS (AE_BAD_PARAMETER);
233    }
234
235    /*
236     * Compute Tick Delta:
237     * -------------------
238     * Handle (max one) timer rollovers on 24- versus 32-bit timers.
239     */
240    if (StartTicks < EndTicks)
241    {
242        DeltaTicks = EndTicks - StartTicks;
243    }
244    else if (StartTicks > EndTicks)
245    {
246        /* 24-bit Timer */
247        if (0 == AcpiGbl_FADT->TmrValExt)
248        {
249            DeltaTicks = (((0x00FFFFFF - StartTicks) + EndTicks) & 0x00FFFFFF);
250        }
251        /* 32-bit Timer */
252        else
253        {
254            DeltaTicks = (0xFFFFFFFF - StartTicks) + EndTicks;
255        }
256    }
257    else
258    {
259        *TimeElapsed = 0;
260        return_ACPI_STATUS (AE_OK);
261    }
262
263    /*
264     * Compute Duration:
265     * -----------------
266     * Since certain compilers (gcc/Linux, argh!) don't support 64-bit
267     * divides in kernel-space we have to do some trickery to preserve
268     * accuracy while using 32-bit math.
269     *
270     * TODO: Change to use 64-bit math when supported.
271     *
272     * The process is as follows:
273     *  1. Compute the number of seconds by dividing Delta Ticks by
274     *     the timer frequency.
275     *  2. Compute the number of milliseconds in the remainder from step #1
276     *     by multiplying by 1000 and then dividing by the timer frequency.
277     *  3. Compute the number of microseconds in the remainder from step #2
278     *     by multiplying by 1000 and then dividing by the timer frequency.
279     *  4. Add the results from steps 1, 2, and 3 to get the total duration.
280     *
281     * Example: The time elapsed for DeltaTicks = 0xFFFFFFFF should be
282     *          1199864031 microseconds.  This is computed as follows:
283     *          Step #1: Seconds = 1199; Remainder = 3092840
284     *          Step #2: Milliseconds = 864; Remainder = 113120
285     *          Step #3: Microseconds = 31; Remainder = <don't care!>
286     */
287
288    /* Step #1 */
289    Seconds = DeltaTicks / PM_TIMER_FREQUENCY;
290    Remainder = DeltaTicks % PM_TIMER_FREQUENCY;
291
292    /* Step #2 */
293    Milliseconds = (Remainder * 1000) / PM_TIMER_FREQUENCY;
294    Remainder = (Remainder * 1000) % PM_TIMER_FREQUENCY;
295
296    /* Step #3 */
297    Microseconds = (Remainder * 1000) / PM_TIMER_FREQUENCY;
298
299    /* Step #4 */
300    *TimeElapsed = Seconds * 1000000;
301    *TimeElapsed += Milliseconds * 1000;
302    *TimeElapsed += Microseconds;
303
304    return_ACPI_STATUS (AE_OK);
305}
306
307
308