aboutsummaryrefslogtreecommitdiff
path: root/include/hw/clock.h
blob: 81bcf3e505a02899faac2a2e503511b262e5eab9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
/*
 * Hardware Clocks
 *
 * Copyright GreenSocs 2016-2020
 *
 * Authors:
 *  Frederic Konrad
 *  Damien Hedde
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 */

#ifndef QEMU_HW_CLOCK_H
#define QEMU_HW_CLOCK_H

#include "qom/object.h"
#include "qemu/queue.h"

#define TYPE_CLOCK "clock"
OBJECT_DECLARE_SIMPLE_TYPE(Clock, CLOCK)

typedef void ClockCallback(void *opaque);

/*
 * clock store a value representing the clock's period in 2^-32ns unit.
 * It can represent:
 *  + periods from 2^-32ns up to 4seconds
 *  + frequency from ~0.25Hz 2e10Ghz
 * Resolution of frequency representation decreases with frequency:
 * + at 100MHz, resolution is ~2mHz
 * + at 1Ghz,   resolution is ~0.2Hz
 * + at 10Ghz,  resolution is ~20Hz
 */
#define CLOCK_PERIOD_1SEC (1000000000llu << 32)

/*
 * macro helpers to convert to hertz / nanosecond
 */
#define CLOCK_PERIOD_FROM_NS(ns) ((ns) * (CLOCK_PERIOD_1SEC / 1000000000llu))
#define CLOCK_PERIOD_TO_NS(per) ((per) / (CLOCK_PERIOD_1SEC / 1000000000llu))
#define CLOCK_PERIOD_FROM_HZ(hz) (((hz) != 0) ? CLOCK_PERIOD_1SEC / (hz) : 0u)
#define CLOCK_PERIOD_TO_HZ(per) (((per) != 0) ? CLOCK_PERIOD_1SEC / (per) : 0u)

/**
 * Clock:
 * @parent_obj: parent class
 * @period: unsigned integer representing the period of the clock
 * @canonical_path: clock path string cache (used for trace purpose)
 * @callback: called when clock changes
 * @callback_opaque: argument for @callback
 * @source: source (or parent in clock tree) of the clock
 * @children: list of clocks connected to this one (it is their source)
 * @sibling: structure used to form a clock list
 */


struct Clock {
    /*< private >*/
    Object parent_obj;

    /* all fields are private and should not be modified directly */

    /* fields */
    uint64_t period;
    char *canonical_path;
    ClockCallback *callback;
    void *callback_opaque;

    /* Clocks are organized in a clock tree */
    Clock *source;
    QLIST_HEAD(, Clock) children;
    QLIST_ENTRY(Clock) sibling;
};

/*
 * vmstate description entry to be added in device vmsd.
 */
extern const VMStateDescription vmstate_clock;
#define VMSTATE_CLOCK(field, state) \
    VMSTATE_CLOCK_V(field, state, 0)
#define VMSTATE_CLOCK_V(field, state, version) \
    VMSTATE_STRUCT_POINTER_V(field, state, version, vmstate_clock, Clock)
#define VMSTATE_ARRAY_CLOCK(field, state, num) \
    VMSTATE_ARRAY_CLOCK_V(field, state, num, 0)
#define VMSTATE_ARRAY_CLOCK_V(field, state, num, version)          \
    VMSTATE_ARRAY_OF_POINTER_TO_STRUCT(field, state, num, version, \
                                       vmstate_clock, Clock)

/**
 * clock_setup_canonical_path:
 * @clk: clock
 *
 * compute the canonical path of the clock (used by log messages)
 */
void clock_setup_canonical_path(Clock *clk);

/**
 * clock_new:
 * @parent: the clock parent
 * @name: the clock object name
 *
 * Helper function to create a new clock and parent it to @parent. There is no
 * need to call clock_setup_canonical_path on the returned clock as it is done
 * by this function.
 *
 * @return the newly created clock
 */
Clock *clock_new(Object *parent, const char *name);

/**
 * clock_set_callback:
 * @clk: the clock to register the callback into
 * @cb: the callback function
 * @opaque: the argument to the callback
 *
 * Register a callback called on every clock update.
 */
void clock_set_callback(Clock *clk, ClockCallback *cb, void *opaque);

/**
 * clock_clear_callback:
 * @clk: the clock to delete the callback from
 *
 * Unregister the callback registered with clock_set_callback.
 */
void clock_clear_callback(Clock *clk);

/**
 * clock_set_source:
 * @clk: the clock.
 * @src: the source clock
 *
 * Setup @src as the clock source of @clk. The current @src period
 * value is also copied to @clk and its subtree but no callback is
 * called.
 * Further @src update will be propagated to @clk and its subtree.
 */
void clock_set_source(Clock *clk, Clock *src);

/**
 * clock_set:
 * @clk: the clock to initialize.
 * @value: the clock's value, 0 means unclocked
 *
 * Set the local cached period value of @clk to @value.
 *
 * @return: true if the clock is changed.
 */
bool clock_set(Clock *clk, uint64_t value);

static inline bool clock_set_hz(Clock *clk, unsigned hz)
{
    return clock_set(clk, CLOCK_PERIOD_FROM_HZ(hz));
}

static inline bool clock_set_ns(Clock *clk, unsigned ns)
{
    return clock_set(clk, CLOCK_PERIOD_FROM_NS(ns));
}

/**
 * clock_propagate:
 * @clk: the clock
 *
 * Propagate the clock period that has been previously configured using
 * @clock_set(). This will update recursively all connected clocks.
 * It is an error to call this function on a clock which has a source.
 * Note: this function must not be called during device inititialization
 * or migration.
 */
void clock_propagate(Clock *clk);

/**
 * clock_update:
 * @clk: the clock to update.
 * @value: the new clock's value, 0 means unclocked
 *
 * Update the @clk to the new @value. All connected clocks will be informed
 * of this update. This is equivalent to call @clock_set() then
 * @clock_propagate().
 */
static inline void clock_update(Clock *clk, uint64_t value)
{
    if (clock_set(clk, value)) {
        clock_propagate(clk);
    }
}

static inline void clock_update_hz(Clock *clk, unsigned hz)
{
    clock_update(clk, CLOCK_PERIOD_FROM_HZ(hz));
}

static inline void clock_update_ns(Clock *clk, unsigned ns)
{
    clock_update(clk, CLOCK_PERIOD_FROM_NS(ns));
}

/**
 * clock_get:
 * @clk: the clk to fetch the clock
 *
 * @return: the current period.
 */
static inline uint64_t clock_get(const Clock *clk)
{
    return clk->period;
}

static inline unsigned clock_get_hz(Clock *clk)
{
    return CLOCK_PERIOD_TO_HZ(clock_get(clk));
}

static inline unsigned clock_get_ns(Clock *clk)
{
    return CLOCK_PERIOD_TO_NS(clock_get(clk));
}

/**
 * clock_is_enabled:
 * @clk: a clock
 *
 * @return: true if the clock is running.
 */
static inline bool clock_is_enabled(const Clock *clk)
{
    return clock_get(clk) != 0;
}

#endif /* QEMU_HW_CLOCK_H */