1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
2 /******************************************************************************
3 *
4 * Name: hwtimer.c - ACPI Power Management Timer Interface
5 *
6 * Copyright (C) 2000 - 2019, Intel Corp.
7 *
8 *****************************************************************************/
9
10 #define EXPORT_ACPI_INTERFACES
11
12 #include <acpi/acpi.h>
13 #include "accommon.h"
14
15 #define _COMPONENT ACPI_HARDWARE
16 ACPI_MODULE_NAME("hwtimer")
17
18 #if (!ACPI_REDUCED_HARDWARE) /* Entire module */
19 /******************************************************************************
20 *
21 * FUNCTION: acpi_get_timer_resolution
22 *
23 * PARAMETERS: resolution - Where the resolution is returned
24 *
25 * RETURN: Status and timer resolution
26 *
27 * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
28 *
29 ******************************************************************************/
30 acpi_status acpi_get_timer_resolution(u32 * resolution)
31 {
32 ACPI_FUNCTION_TRACE(acpi_get_timer_resolution);
33
34 if (!resolution) {
35 return_ACPI_STATUS(AE_BAD_PARAMETER);
36 }
37
38 if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
39 *resolution = 24;
40 } else {
41 *resolution = 32;
42 }
43
44 return_ACPI_STATUS(AE_OK);
45 }
46
47 ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution)
48
49 /******************************************************************************
50 *
51 * FUNCTION: acpi_get_timer
52 *
53 * PARAMETERS: ticks - Where the timer value is returned
54 *
55 * RETURN: Status and current timer value (ticks)
56 *
57 * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
58 *
59 ******************************************************************************/
60 acpi_status acpi_get_timer(u32 * ticks)
61 {
62 acpi_status status;
63 u64 timer_value;
64
65 ACPI_FUNCTION_TRACE(acpi_get_timer);
66
67 if (!ticks) {
68 return_ACPI_STATUS(AE_BAD_PARAMETER);
69 }
70
71 /* ACPI 5.0A: PM Timer is optional */
72
73 if (!acpi_gbl_FADT.xpm_timer_block.address) {
74 return_ACPI_STATUS(AE_SUPPORT);
75 }
76
77 status = acpi_hw_read(&timer_value, &acpi_gbl_FADT.xpm_timer_block);
78 if (ACPI_SUCCESS(status)) {
79
80 /* ACPI PM Timer is defined to be 32 bits (PM_TMR_LEN) */
81
82 *ticks = (u32)timer_value;
83 }
84
85 return_ACPI_STATUS(status);
86 }
87
88 ACPI_EXPORT_SYMBOL(acpi_get_timer)
89
90 /******************************************************************************
91 *
92 * FUNCTION: acpi_get_timer_duration
93 *
94 * PARAMETERS: start_ticks - Starting timestamp
95 * end_ticks - End timestamp
96 * time_elapsed - Where the elapsed time is returned
97 *
98 * RETURN: Status and time_elapsed
99 *
100 * DESCRIPTION: Computes the time elapsed (in microseconds) between two
101 * PM Timer time stamps, taking into account the possibility of
102 * rollovers, the timer resolution, and timer frequency.
103 *
104 * The PM Timer's clock ticks at roughly 3.6 times per
105 * _microsecond_, and its clock continues through Cx state
106 * transitions (unlike many CPU timestamp counters) -- making it
107 * a versatile and accurate timer.
108 *
109 * Note that this function accommodates only a single timer
110 * rollover. Thus for 24-bit timers, this function should only
111 * be used for calculating durations less than ~4.6 seconds
112 * (~20 minutes for 32-bit timers) -- calculations below:
113 *
114 * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
115 * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
116 *
117 ******************************************************************************/
118 acpi_status
119 acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 *time_elapsed)
120 {
121 acpi_status status;
122 u64 delta_ticks;
123 u64 quotient;
124
125 ACPI_FUNCTION_TRACE(acpi_get_timer_duration);
126
127 if (!time_elapsed) {
128 return_ACPI_STATUS(AE_BAD_PARAMETER);
129 }
130
131 /* ACPI 5.0A: PM Timer is optional */
132
133 if (!acpi_gbl_FADT.xpm_timer_block.address) {
134 return_ACPI_STATUS(AE_SUPPORT);
135 }
136
137 if (start_ticks == end_ticks) {
138 *time_elapsed = 0;
139 return_ACPI_STATUS(AE_OK);
140 }
141
142 /*
143 * Compute Tick Delta:
144 * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
145 */
146 delta_ticks = end_ticks;
147 if (start_ticks > end_ticks) {
148 if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
149
150 /* 24-bit Timer */
151
152 delta_ticks |= (u64)1 << 24;
153 } else {
154 /* 32-bit Timer */
155
156 delta_ticks |= (u64)1 << 32;
157 }
158 }
159 delta_ticks -= start_ticks;
160
161 /*
162 * Compute Duration (Requires a 64-bit multiply and divide):
163 *
164 * time_elapsed (microseconds) =
165 * (delta_ticks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY;
166 */
167 status = acpi_ut_short_divide(delta_ticks * ACPI_USEC_PER_SEC,
168 ACPI_PM_TIMER_FREQUENCY, "ient, NULL);
169
170 *time_elapsed = (u32)quotient;
171 return_ACPI_STATUS(status);
172 }
173
174 ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
175 #endif /* !ACPI_REDUCED_HARDWARE */