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 - 2023, 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
16ACPI_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 ******************************************************************************/
30acpi_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
47ACPI_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 ******************************************************************************/
60acpi_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
88ACPI_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 ******************************************************************************/
118acpi_status
119acpi_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, &quotient, NULL);
169
170	*time_elapsed = (u32)quotient;
171	return_ACPI_STATUS(status);
172}
173
174ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
175#endif				/* !ACPI_REDUCED_HARDWARE */
176