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
50ACPI_MODULE_NAME("hwtimer")
51
52#if (!ACPI_REDUCED_HARDWARE)	/* Entire module */
53/******************************************************************************
54 *
55 * FUNCTION:    acpi_get_timer_resolution
56 *
57 * PARAMETERS:  Resolution          - Where the resolution is returned
58 *
59 * RETURN:      Status and timer resolution
60 *
61 * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
62 *
63 ******************************************************************************/
64acpi_status acpi_get_timer_resolution(u32 * resolution)
65{
66	ACPI_FUNCTION_TRACE(acpi_get_timer_resolution);
67
68	if (!resolution) {
69		return_ACPI_STATUS(AE_BAD_PARAMETER);
70	}
71
72	if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
73		*resolution = 24;
74	} else {
75		*resolution = 32;
76	}
77
78	return_ACPI_STATUS(AE_OK);
79}
80
81ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution)
82
83/******************************************************************************
84 *
85 * FUNCTION:    acpi_get_timer
86 *
87 * PARAMETERS:  Ticks               - Where the timer value is returned
88 *
89 * RETURN:      Status and current timer value (ticks)
90 *
91 * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
92 *
93 ******************************************************************************/
94acpi_status acpi_get_timer(u32 * ticks)
95{
96	acpi_status status;
97
98	ACPI_FUNCTION_TRACE(acpi_get_timer);
99
100	if (!ticks) {
101		return_ACPI_STATUS(AE_BAD_PARAMETER);
102	}
103
104	status =
105	    acpi_hw_read(ticks, &acpi_gbl_FADT.xpm_timer_block);
106
107	return_ACPI_STATUS(status);
108}
109
110ACPI_EXPORT_SYMBOL(acpi_get_timer)
111
112/******************************************************************************
113 *
114 * FUNCTION:    acpi_get_timer_duration
115 *
116 * PARAMETERS:  start_ticks         - Starting timestamp
117 *              end_ticks           - End timestamp
118 *              time_elapsed        - Where the elapsed time is returned
119 *
120 * RETURN:      Status and time_elapsed
121 *
122 * DESCRIPTION: Computes the time elapsed (in microseconds) between two
123 *              PM Timer time stamps, taking into account the possibility of
124 *              rollovers, the timer resolution, and timer frequency.
125 *
126 *              The PM Timer's clock ticks at roughly 3.6 times per
127 *              _microsecond_, and its clock continues through Cx state
128 *              transitions (unlike many CPU timestamp counters) -- making it
129 *              a versatile and accurate timer.
130 *
131 *              Note that this function accommodates only a single timer
132 *              rollover.  Thus for 24-bit timers, this function should only
133 *              be used for calculating durations less than ~4.6 seconds
134 *              (~20 minutes for 32-bit timers) -- calculations below:
135 *
136 *              2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
137 *              2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
138 *
139 ******************************************************************************/
140acpi_status
141acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 * time_elapsed)
142{
143	acpi_status status;
144	u32 delta_ticks;
145	u64 quotient;
146
147	ACPI_FUNCTION_TRACE(acpi_get_timer_duration);
148
149	if (!time_elapsed) {
150		return_ACPI_STATUS(AE_BAD_PARAMETER);
151	}
152
153	/*
154	 * Compute Tick Delta:
155	 * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
156	 */
157	if (start_ticks < end_ticks) {
158		delta_ticks = end_ticks - start_ticks;
159	} else if (start_ticks > end_ticks) {
160		if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
161
162			/* 24-bit Timer */
163
164			delta_ticks =
165			    (((0x00FFFFFF - start_ticks) +
166			      end_ticks) & 0x00FFFFFF);
167		} else {
168			/* 32-bit Timer */
169
170			delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks;
171		}
172	} else {		/* start_ticks == end_ticks */
173
174		*time_elapsed = 0;
175		return_ACPI_STATUS(AE_OK);
176	}
177
178	/*
179	 * Compute Duration (Requires a 64-bit multiply and divide):
180	 *
181	 * time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY;
182	 */
183	status = acpi_ut_short_divide(((u64) delta_ticks) * 1000000,
184				      PM_TIMER_FREQUENCY, &quotient, NULL);
185
186	*time_elapsed = (u32) quotient;
187	return_ACPI_STATUS(status);
188}
189
190ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
191#endif				/* !ACPI_REDUCED_HARDWARE */
192