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49d4d9b6 PB |
1 | /* |
2 | * General purpose implementation of a simple periodic countdown timer. | |
3 | * | |
4 | * Copyright (c) 2007 CodeSourcery. | |
5 | * | |
6 | * This code is licensed under the GNU LGPL. | |
7 | */ | |
8 | #ifndef PTIMER_H | |
9 | #define PTIMER_H | |
10 | ||
11 | #include "qemu-common.h" | |
1de7afc9 | 12 | #include "qemu/timer.h" |
caf71f86 | 13 | #include "migration/vmstate.h" |
49d4d9b6 | 14 | |
a7a305ae PM |
15 | /* The ptimer API implements a simple periodic countdown timer. |
16 | * The countdown timer has a value (which can be read and written via | |
17 | * ptimer_get_count() and ptimer_set_count()). When it is enabled | |
18 | * using ptimer_run(), the value will count downwards at the frequency | |
19 | * which has been configured using ptimer_set_period() or ptimer_set_freq(). | |
20 | * When it reaches zero it will trigger a QEMU bottom half handler, and | |
21 | * can be set to either reload itself from a specified limit value | |
22 | * and keep counting down, or to stop (as a one-shot timer). | |
23 | * | |
24 | * Forgetting to set the period/frequency (or setting it to zero) is a | |
25 | * bug in the QEMU device and will cause warning messages to be printed | |
26 | * to stderr when the guest attempts to enable the timer. | |
27 | */ | |
28 | ||
e7ea81c3 DO |
29 | /* The default ptimer policy retains backward compatibility with the legacy |
30 | * timers. Custom policies are adjusting the default one. Consider providing | |
31 | * a correct policy for your timer. | |
32 | * | |
33 | * The rough edges of the default policy: | |
34 | * - Starting to run with a period = 0 emits error message and stops the | |
35 | * timer without a trigger. | |
36 | * | |
37 | * - Setting period to 0 of the running timer emits error message and | |
38 | * stops the timer without a trigger. | |
39 | * | |
40 | * - Starting to run with counter = 0 or setting it to "0" while timer | |
41 | * is running causes a trigger and reloads counter with a limit value. | |
42 | * If limit = 0, ptimer emits error message and stops the timer. | |
43 | * | |
44 | * - Counter value of the running timer is one less than the actual value. | |
45 | * | |
46 | * - Changing period/frequency of the running timer loses time elapsed | |
47 | * since the last period, effectively restarting the timer with a | |
48 | * counter = counter value at the moment of change (.i.e. one less). | |
49 | */ | |
50 | #define PTIMER_POLICY_DEFAULT 0 | |
51 | ||
2b5c0322 DO |
52 | /* Periodic timer counter stays with "0" for a one period before wrapping |
53 | * around. */ | |
54 | #define PTIMER_POLICY_WRAP_AFTER_ONE_PERIOD (1 << 0) | |
55 | ||
ef0a9984 DO |
56 | /* Running periodic timer that has counter = limit = 0 would continuously |
57 | * re-trigger every period. */ | |
58 | #define PTIMER_POLICY_CONTINUOUS_TRIGGER (1 << 1) | |
59 | ||
22471b8a DO |
60 | /* Starting to run with/setting counter to "0" won't trigger immediately, |
61 | * but after a one period for both oneshot and periodic modes. */ | |
62 | #define PTIMER_POLICY_NO_IMMEDIATE_TRIGGER (1 << 2) | |
63 | ||
3f6e6a13 DO |
64 | /* Starting to run with/setting counter to "0" won't re-load counter |
65 | * immediately, but after a one period. */ | |
66 | #define PTIMER_POLICY_NO_IMMEDIATE_RELOAD (1 << 3) | |
67 | ||
5580ea45 DO |
68 | /* Make counter value of the running timer represent the actual value and |
69 | * not the one less. */ | |
70 | #define PTIMER_POLICY_NO_COUNTER_ROUND_DOWN (1 << 4) | |
71 | ||
086ede32 PM |
72 | /* |
73 | * Starting to run with a zero counter, or setting the counter to "0" via | |
74 | * ptimer_set_count() or ptimer_set_limit() will not trigger the timer | |
75 | * (though it will cause a reload). Only a counter decrement to "0" | |
76 | * will cause a trigger. Not compatible with NO_IMMEDIATE_TRIGGER; | |
77 | * ptimer_init() will assert() that you don't set both. | |
78 | */ | |
79 | #define PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT (1 << 5) | |
80 | ||
49d4d9b6 PB |
81 | /* ptimer.c */ |
82 | typedef struct ptimer_state ptimer_state; | |
83 | typedef void (*ptimer_cb)(void *opaque); | |
84 | ||
a7a305ae PM |
85 | /** |
86 | * ptimer_init - Allocate and return a new ptimer | |
87 | * @bh: QEMU bottom half which is run on timer expiry | |
88 | * @policy: PTIMER_POLICY_* bits specifying behaviour | |
89 | * | |
90 | * The ptimer returned must be freed using ptimer_free(). | |
91 | * The ptimer takes ownership of @bh and will delete it | |
92 | * when the ptimer is eventually freed. | |
93 | */ | |
e7ea81c3 | 94 | ptimer_state *ptimer_init(QEMUBH *bh, uint8_t policy_mask); |
a7a305ae PM |
95 | |
96 | /** | |
97 | * ptimer_free - Free a ptimer | |
98 | * @s: timer to free | |
99 | * | |
100 | * Free a ptimer created using ptimer_init() (including | |
101 | * deleting the bottom half which it is using). | |
102 | */ | |
072bdb07 | 103 | void ptimer_free(ptimer_state *s); |
a7a305ae PM |
104 | |
105 | /** | |
106 | * ptimer_set_period - Set counter increment interval in nanoseconds | |
107 | * @s: ptimer to configure | |
108 | * @period: period of the counter in nanoseconds | |
109 | * | |
110 | * Note that if your counter behaviour is specified as having a | |
111 | * particular frequency rather than a period then ptimer_set_freq() | |
112 | * may be more appropriate. | |
113 | */ | |
49d4d9b6 | 114 | void ptimer_set_period(ptimer_state *s, int64_t period); |
a7a305ae PM |
115 | |
116 | /** | |
117 | * ptimer_set_freq - Set counter frequency in Hz | |
118 | * @s: ptimer to configure | |
119 | * @freq: counter frequency in Hz | |
120 | * | |
121 | * This does the same thing as ptimer_set_period(), so you only | |
122 | * need to call one of them. If the counter behaviour is specified | |
123 | * as setting the frequency then this function is more appropriate, | |
124 | * because it allows specifying an effective period which is | |
125 | * precise to fractions of a nanosecond, avoiding rounding errors. | |
126 | */ | |
49d4d9b6 | 127 | void ptimer_set_freq(ptimer_state *s, uint32_t freq); |
a7a305ae PM |
128 | |
129 | /** | |
130 | * ptimer_get_limit - Get the configured limit of the ptimer | |
131 | * @s: ptimer to query | |
132 | * | |
133 | * This function returns the current limit (reload) value | |
134 | * of the down-counter; that is, the value which it will be | |
135 | * reset to when it hits zero. | |
136 | * | |
137 | * Generally timer devices using ptimers should be able to keep | |
138 | * their reload register state inside the ptimer using the get | |
139 | * and set limit functions rather than needing to also track it | |
140 | * in their own state structure. | |
141 | */ | |
578c4b2f | 142 | uint64_t ptimer_get_limit(ptimer_state *s); |
a7a305ae PM |
143 | |
144 | /** | |
145 | * ptimer_set_limit - Set the limit of the ptimer | |
146 | * @s: ptimer | |
147 | * @limit: initial countdown value | |
148 | * @reload: if nonzero, then reset the counter to the new limit | |
149 | * | |
150 | * Set the limit value of the down-counter. The @reload flag can | |
151 | * be used to emulate the behaviour of timers which immediately | |
152 | * reload the counter when their reload register is written to. | |
153 | */ | |
49d4d9b6 | 154 | void ptimer_set_limit(ptimer_state *s, uint64_t limit, int reload); |
a7a305ae PM |
155 | |
156 | /** | |
157 | * ptimer_get_count - Get the current value of the ptimer | |
158 | * @s: ptimer | |
159 | * | |
160 | * Return the current value of the down-counter. This will | |
161 | * return the correct value whether the counter is enabled or | |
162 | * disabled. | |
163 | */ | |
49d4d9b6 | 164 | uint64_t ptimer_get_count(ptimer_state *s); |
a7a305ae PM |
165 | |
166 | /** | |
167 | * ptimer_set_count - Set the current value of the ptimer | |
168 | * @s: ptimer | |
169 | * @count: count value to set | |
170 | * | |
171 | * Set the value of the down-counter. If the counter is currently | |
172 | * enabled this will arrange for a timer callback at the appropriate | |
173 | * point in the future. | |
174 | */ | |
49d4d9b6 | 175 | void ptimer_set_count(ptimer_state *s, uint64_t count); |
a7a305ae PM |
176 | |
177 | /** | |
178 | * ptimer_run - Start a ptimer counting | |
179 | * @s: ptimer | |
180 | * @oneshot: non-zero if this timer should only count down once | |
181 | * | |
182 | * Start a ptimer counting down; when it reaches zero the bottom half | |
183 | * passed to ptimer_init() will be invoked. If the @oneshot argument is zero, | |
184 | * the counter value will then be reloaded from the limit and it will | |
185 | * start counting down again. If @oneshot is non-zero, then the counter | |
186 | * will disable itself when it reaches zero. | |
187 | */ | |
49d4d9b6 | 188 | void ptimer_run(ptimer_state *s, int oneshot); |
a7a305ae PM |
189 | |
190 | /** | |
191 | * ptimer_stop - Stop a ptimer counting | |
192 | * @s: ptimer | |
193 | * | |
194 | * Pause a timer (the count stays at its current value until ptimer_run() | |
195 | * is called to start it counting again). | |
196 | * | |
197 | * Note that this can cause it to "lose" time, even if it is immediately | |
198 | * restarted. | |
199 | */ | |
49d4d9b6 PB |
200 | void ptimer_stop(ptimer_state *s); |
201 | ||
701a8f76 PB |
202 | extern const VMStateDescription vmstate_ptimer; |
203 | ||
20bcf73f PM |
204 | #define VMSTATE_PTIMER(_field, _state) \ |
205 | VMSTATE_STRUCT_POINTER_V(_field, _state, 1, vmstate_ptimer, ptimer_state) | |
701a8f76 | 206 | |
a1f05e79 PM |
207 | #define VMSTATE_PTIMER_ARRAY(_f, _s, _n) \ |
208 | VMSTATE_ARRAY_OF_POINTER_TO_STRUCT(_f, _s, _n, 0, \ | |
209 | vmstate_ptimer, ptimer_state) | |
210 | ||
49d4d9b6 | 211 | #endif |