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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 | ||
1de7afc9 | 11 | #include "qemu/timer.h" |
49d4d9b6 | 12 | |
af2a580f PM |
13 | /* |
14 | * The ptimer API implements a simple periodic countdown timer. | |
a7a305ae PM |
15 | * The countdown timer has a value (which can be read and written via |
16 | * ptimer_get_count() and ptimer_set_count()). When it is enabled | |
17 | * using ptimer_run(), the value will count downwards at the frequency | |
18 | * which has been configured using ptimer_set_period() or ptimer_set_freq(). | |
af2a580f | 19 | * When it reaches zero it will trigger a callback function, and |
a7a305ae PM |
20 | * can be set to either reload itself from a specified limit value |
21 | * and keep counting down, or to stop (as a one-shot timer). | |
22 | * | |
af2a580f PM |
23 | * A transaction-based API is used for modifying ptimer state: all calls |
24 | * to functions which modify ptimer state must be between matched calls to | |
25 | * ptimer_transaction_begin() and ptimer_transaction_commit(). | |
26 | * When ptimer_transaction_commit() is called it will evaluate the state | |
27 | * of the timer after all the changes in the transaction, and call the | |
28 | * callback if necessary. (See the ptimer_init() documentation for the full | |
29 | * list of state-modifying functions and detailed semantics of the callback.) | |
30 | * | |
a7a305ae PM |
31 | * Forgetting to set the period/frequency (or setting it to zero) is a |
32 | * bug in the QEMU device and will cause warning messages to be printed | |
33 | * to stderr when the guest attempts to enable the timer. | |
34 | */ | |
35 | ||
e7ea81c3 DO |
36 | /* The default ptimer policy retains backward compatibility with the legacy |
37 | * timers. Custom policies are adjusting the default one. Consider providing | |
38 | * a correct policy for your timer. | |
39 | * | |
40 | * The rough edges of the default policy: | |
41 | * - Starting to run with a period = 0 emits error message and stops the | |
42 | * timer without a trigger. | |
43 | * | |
44 | * - Setting period to 0 of the running timer emits error message and | |
45 | * stops the timer without a trigger. | |
46 | * | |
47 | * - Starting to run with counter = 0 or setting it to "0" while timer | |
48 | * is running causes a trigger and reloads counter with a limit value. | |
49 | * If limit = 0, ptimer emits error message and stops the timer. | |
50 | * | |
51 | * - Counter value of the running timer is one less than the actual value. | |
52 | * | |
53 | * - Changing period/frequency of the running timer loses time elapsed | |
54 | * since the last period, effectively restarting the timer with a | |
55 | * counter = counter value at the moment of change (.i.e. one less). | |
56 | */ | |
57 | #define PTIMER_POLICY_DEFAULT 0 | |
58 | ||
2b5c0322 DO |
59 | /* Periodic timer counter stays with "0" for a one period before wrapping |
60 | * around. */ | |
61 | #define PTIMER_POLICY_WRAP_AFTER_ONE_PERIOD (1 << 0) | |
62 | ||
ef0a9984 DO |
63 | /* Running periodic timer that has counter = limit = 0 would continuously |
64 | * re-trigger every period. */ | |
65 | #define PTIMER_POLICY_CONTINUOUS_TRIGGER (1 << 1) | |
66 | ||
22471b8a DO |
67 | /* Starting to run with/setting counter to "0" won't trigger immediately, |
68 | * but after a one period for both oneshot and periodic modes. */ | |
69 | #define PTIMER_POLICY_NO_IMMEDIATE_TRIGGER (1 << 2) | |
70 | ||
3f6e6a13 DO |
71 | /* Starting to run with/setting counter to "0" won't re-load counter |
72 | * immediately, but after a one period. */ | |
73 | #define PTIMER_POLICY_NO_IMMEDIATE_RELOAD (1 << 3) | |
74 | ||
5580ea45 DO |
75 | /* Make counter value of the running timer represent the actual value and |
76 | * not the one less. */ | |
77 | #define PTIMER_POLICY_NO_COUNTER_ROUND_DOWN (1 << 4) | |
78 | ||
086ede32 PM |
79 | /* |
80 | * Starting to run with a zero counter, or setting the counter to "0" via | |
81 | * ptimer_set_count() or ptimer_set_limit() will not trigger the timer | |
82 | * (though it will cause a reload). Only a counter decrement to "0" | |
83 | * will cause a trigger. Not compatible with NO_IMMEDIATE_TRIGGER; | |
af2a580f | 84 | * ptimer_init() will assert() that you don't set both. |
086ede32 PM |
85 | */ |
86 | #define PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT (1 << 5) | |
87 | ||
49d4d9b6 PB |
88 | /* ptimer.c */ |
89 | typedef struct ptimer_state ptimer_state; | |
90 | typedef void (*ptimer_cb)(void *opaque); | |
91 | ||
78b6eaa6 PM |
92 | /** |
93 | * ptimer_init - Allocate and return a new ptimer | |
94 | * @callback: function to call on ptimer expiry | |
95 | * @callback_opaque: opaque pointer passed to @callback | |
96 | * @policy: PTIMER_POLICY_* bits specifying behaviour | |
97 | * | |
98 | * The ptimer returned must be freed using ptimer_free(). | |
99 | * | |
100 | * If a ptimer is created using this API then will use the | |
101 | * transaction-based API for modifying ptimer state: all calls | |
102 | * to functions which modify ptimer state: | |
103 | * - ptimer_set_period() | |
104 | * - ptimer_set_freq() | |
105 | * - ptimer_set_limit() | |
106 | * - ptimer_set_count() | |
107 | * - ptimer_run() | |
108 | * - ptimer_stop() | |
109 | * must be between matched calls to ptimer_transaction_begin() | |
110 | * and ptimer_transaction_commit(). When ptimer_transaction_commit() | |
111 | * is called it will evaluate the state of the timer after all the | |
112 | * changes in the transaction, and call the callback if necessary. | |
113 | * | |
114 | * The callback function is always called from within a transaction | |
115 | * begin/commit block, so the callback should not call the | |
116 | * ptimer_transaction_begin() function itself. If the callback changes | |
117 | * the ptimer state such that another ptimer expiry is triggered, then | |
118 | * the callback will be called a second time after the first call returns. | |
119 | */ | |
120 | ptimer_state *ptimer_init(ptimer_cb callback, | |
121 | void *callback_opaque, | |
122 | uint8_t policy_mask); | |
123 | ||
a7a305ae PM |
124 | /** |
125 | * ptimer_free - Free a ptimer | |
126 | * @s: timer to free | |
127 | * | |
af2a580f | 128 | * Free a ptimer created using ptimer_init(). |
a7a305ae | 129 | */ |
072bdb07 | 130 | void ptimer_free(ptimer_state *s); |
a7a305ae | 131 | |
78b6eaa6 PM |
132 | /** |
133 | * ptimer_transaction_begin() - Start a ptimer modification transaction | |
134 | * | |
135 | * This function must be called before making any calls to functions | |
136 | * which modify the ptimer's state (see the ptimer_init() documentation | |
137 | * for a list of these), and must always have a matched call to | |
138 | * ptimer_transaction_commit(). | |
139 | * It is an error to call this function for a BH-based ptimer; | |
140 | * attempting to do this will trigger an assert. | |
141 | */ | |
142 | void ptimer_transaction_begin(ptimer_state *s); | |
143 | ||
144 | /** | |
145 | * ptimer_transaction_commit() - Commit a ptimer modification transaction | |
146 | * | |
147 | * This function must be called after calls to functions which modify | |
148 | * the ptimer's state, and completes the update of the ptimer. If the | |
149 | * ptimer state now means that we should trigger the timer expiry | |
150 | * callback, it will be called directly. | |
151 | */ | |
152 | void ptimer_transaction_commit(ptimer_state *s); | |
153 | ||
a7a305ae PM |
154 | /** |
155 | * ptimer_set_period - Set counter increment interval in nanoseconds | |
156 | * @s: ptimer to configure | |
157 | * @period: period of the counter in nanoseconds | |
158 | * | |
159 | * Note that if your counter behaviour is specified as having a | |
160 | * particular frequency rather than a period then ptimer_set_freq() | |
161 | * may be more appropriate. | |
78b6eaa6 PM |
162 | * |
163 | * This function will assert if it is called outside a | |
af2a580f | 164 | * ptimer_transaction_begin/commit block. |
a7a305ae | 165 | */ |
49d4d9b6 | 166 | void ptimer_set_period(ptimer_state *s, int64_t period); |
a7a305ae PM |
167 | |
168 | /** | |
169 | * ptimer_set_freq - Set counter frequency in Hz | |
170 | * @s: ptimer to configure | |
171 | * @freq: counter frequency in Hz | |
172 | * | |
173 | * This does the same thing as ptimer_set_period(), so you only | |
174 | * need to call one of them. If the counter behaviour is specified | |
175 | * as setting the frequency then this function is more appropriate, | |
176 | * because it allows specifying an effective period which is | |
177 | * precise to fractions of a nanosecond, avoiding rounding errors. | |
78b6eaa6 PM |
178 | * |
179 | * This function will assert if it is called outside a | |
af2a580f | 180 | * ptimer_transaction_begin/commit block. |
a7a305ae | 181 | */ |
49d4d9b6 | 182 | void ptimer_set_freq(ptimer_state *s, uint32_t freq); |
a7a305ae PM |
183 | |
184 | /** | |
185 | * ptimer_get_limit - Get the configured limit of the ptimer | |
186 | * @s: ptimer to query | |
187 | * | |
188 | * This function returns the current limit (reload) value | |
189 | * of the down-counter; that is, the value which it will be | |
190 | * reset to when it hits zero. | |
191 | * | |
192 | * Generally timer devices using ptimers should be able to keep | |
193 | * their reload register state inside the ptimer using the get | |
194 | * and set limit functions rather than needing to also track it | |
195 | * in their own state structure. | |
196 | */ | |
578c4b2f | 197 | uint64_t ptimer_get_limit(ptimer_state *s); |
a7a305ae PM |
198 | |
199 | /** | |
200 | * ptimer_set_limit - Set the limit of the ptimer | |
201 | * @s: ptimer | |
202 | * @limit: initial countdown value | |
203 | * @reload: if nonzero, then reset the counter to the new limit | |
204 | * | |
205 | * Set the limit value of the down-counter. The @reload flag can | |
206 | * be used to emulate the behaviour of timers which immediately | |
207 | * reload the counter when their reload register is written to. | |
78b6eaa6 PM |
208 | * |
209 | * This function will assert if it is called outside a | |
af2a580f | 210 | * ptimer_transaction_begin/commit block. |
a7a305ae | 211 | */ |
49d4d9b6 | 212 | void ptimer_set_limit(ptimer_state *s, uint64_t limit, int reload); |
a7a305ae PM |
213 | |
214 | /** | |
215 | * ptimer_get_count - Get the current value of the ptimer | |
216 | * @s: ptimer | |
217 | * | |
218 | * Return the current value of the down-counter. This will | |
219 | * return the correct value whether the counter is enabled or | |
220 | * disabled. | |
221 | */ | |
49d4d9b6 | 222 | uint64_t ptimer_get_count(ptimer_state *s); |
a7a305ae PM |
223 | |
224 | /** | |
225 | * ptimer_set_count - Set the current value of the ptimer | |
226 | * @s: ptimer | |
227 | * @count: count value to set | |
228 | * | |
229 | * Set the value of the down-counter. If the counter is currently | |
230 | * enabled this will arrange for a timer callback at the appropriate | |
231 | * point in the future. | |
78b6eaa6 PM |
232 | * |
233 | * This function will assert if it is called outside a | |
af2a580f | 234 | * ptimer_transaction_begin/commit block. |
a7a305ae | 235 | */ |
49d4d9b6 | 236 | void ptimer_set_count(ptimer_state *s, uint64_t count); |
a7a305ae PM |
237 | |
238 | /** | |
239 | * ptimer_run - Start a ptimer counting | |
240 | * @s: ptimer | |
241 | * @oneshot: non-zero if this timer should only count down once | |
242 | * | |
af2a580f PM |
243 | * Start a ptimer counting down; when it reaches zero the callback function |
244 | * passed to ptimer_init() will be invoked. | |
b0142262 | 245 | * If the @oneshot argument is zero, |
a7a305ae PM |
246 | * the counter value will then be reloaded from the limit and it will |
247 | * start counting down again. If @oneshot is non-zero, then the counter | |
248 | * will disable itself when it reaches zero. | |
78b6eaa6 PM |
249 | * |
250 | * This function will assert if it is called outside a | |
af2a580f | 251 | * ptimer_transaction_begin/commit block. |
a7a305ae | 252 | */ |
49d4d9b6 | 253 | void ptimer_run(ptimer_state *s, int oneshot); |
a7a305ae PM |
254 | |
255 | /** | |
256 | * ptimer_stop - Stop a ptimer counting | |
257 | * @s: ptimer | |
258 | * | |
259 | * Pause a timer (the count stays at its current value until ptimer_run() | |
260 | * is called to start it counting again). | |
261 | * | |
262 | * Note that this can cause it to "lose" time, even if it is immediately | |
263 | * restarted. | |
78b6eaa6 PM |
264 | * |
265 | * This function will assert if it is called outside a | |
af2a580f | 266 | * ptimer_transaction_begin/commit block. |
a7a305ae | 267 | */ |
49d4d9b6 PB |
268 | void ptimer_stop(ptimer_state *s); |
269 | ||
701a8f76 PB |
270 | extern const VMStateDescription vmstate_ptimer; |
271 | ||
20bcf73f PM |
272 | #define VMSTATE_PTIMER(_field, _state) \ |
273 | VMSTATE_STRUCT_POINTER_V(_field, _state, 1, vmstate_ptimer, ptimer_state) | |
701a8f76 | 274 | |
a1f05e79 PM |
275 | #define VMSTATE_PTIMER_ARRAY(_f, _s, _n) \ |
276 | VMSTATE_ARRAY_OF_POINTER_TO_STRUCT(_f, _s, _n, 0, \ | |
277 | vmstate_ptimer, ptimer_state) | |
278 | ||
49d4d9b6 | 279 | #endif |