Merge remote-tracking branch 'remotes/rth/tags/pull-tcg-20210921' into staging
[qemu.git] / include / hw / clock.h
1 /*
2 * Hardware Clocks
3 *
4 * Copyright GreenSocs 2016-2020
5 *
6 * Authors:
7 * Frederic Konrad
8 * Damien Hedde
9 *
10 * This work is licensed under the terms of the GNU GPL, version 2 or later.
11 * See the COPYING file in the top-level directory.
12 */
13
14 #ifndef QEMU_HW_CLOCK_H
15 #define QEMU_HW_CLOCK_H
16
17 #include "qom/object.h"
18 #include "qemu/queue.h"
19 #include "qemu/host-utils.h"
20 #include "qemu/bitops.h"
21
22 #define TYPE_CLOCK "clock"
23 OBJECT_DECLARE_SIMPLE_TYPE(Clock, CLOCK)
24
25 /*
26 * Argument to ClockCallback functions indicating why the callback
27 * has been called. A mask of these values logically ORed together
28 * is used to specify which events are interesting when the callback
29 * is registered, so these values must all be different bit values.
30 */
31 typedef enum ClockEvent {
32 ClockUpdate = 1, /* Clock period has just updated */
33 ClockPreUpdate = 2, /* Clock period is about to update */
34 } ClockEvent;
35
36 typedef void ClockCallback(void *opaque, ClockEvent event);
37
38 /*
39 * clock store a value representing the clock's period in 2^-32ns unit.
40 * It can represent:
41 * + periods from 2^-32ns up to 4seconds
42 * + frequency from ~0.25Hz 2e10Ghz
43 * Resolution of frequency representation decreases with frequency:
44 * + at 100MHz, resolution is ~2mHz
45 * + at 1Ghz, resolution is ~0.2Hz
46 * + at 10Ghz, resolution is ~20Hz
47 */
48 #define CLOCK_PERIOD_1SEC (1000000000llu << 32)
49
50 /*
51 * macro helpers to convert to hertz / nanosecond
52 */
53 #define CLOCK_PERIOD_FROM_NS(ns) ((ns) * (CLOCK_PERIOD_1SEC / 1000000000llu))
54 #define CLOCK_PERIOD_FROM_HZ(hz) (((hz) != 0) ? CLOCK_PERIOD_1SEC / (hz) : 0u)
55 #define CLOCK_PERIOD_TO_HZ(per) (((per) != 0) ? CLOCK_PERIOD_1SEC / (per) : 0u)
56
57 /**
58 * Clock:
59 * @parent_obj: parent class
60 * @period: unsigned integer representing the period of the clock
61 * @canonical_path: clock path string cache (used for trace purpose)
62 * @callback: called when clock changes
63 * @callback_opaque: argument for @callback
64 * @callback_events: mask of events when callback should be called
65 * @source: source (or parent in clock tree) of the clock
66 * @children: list of clocks connected to this one (it is their source)
67 * @sibling: structure used to form a clock list
68 */
69
70
71 struct Clock {
72 /*< private >*/
73 Object parent_obj;
74
75 /* all fields are private and should not be modified directly */
76
77 /* fields */
78 uint64_t period;
79 char *canonical_path;
80 ClockCallback *callback;
81 void *callback_opaque;
82 unsigned int callback_events;
83
84 /* Clocks are organized in a clock tree */
85 Clock *source;
86 QLIST_HEAD(, Clock) children;
87 QLIST_ENTRY(Clock) sibling;
88 };
89
90 /*
91 * vmstate description entry to be added in device vmsd.
92 */
93 extern const VMStateDescription vmstate_clock;
94 #define VMSTATE_CLOCK(field, state) \
95 VMSTATE_CLOCK_V(field, state, 0)
96 #define VMSTATE_CLOCK_V(field, state, version) \
97 VMSTATE_STRUCT_POINTER_V(field, state, version, vmstate_clock, Clock)
98 #define VMSTATE_ARRAY_CLOCK(field, state, num) \
99 VMSTATE_ARRAY_CLOCK_V(field, state, num, 0)
100 #define VMSTATE_ARRAY_CLOCK_V(field, state, num, version) \
101 VMSTATE_ARRAY_OF_POINTER_TO_STRUCT(field, state, num, version, \
102 vmstate_clock, Clock)
103
104 /**
105 * clock_setup_canonical_path:
106 * @clk: clock
107 *
108 * compute the canonical path of the clock (used by log messages)
109 */
110 void clock_setup_canonical_path(Clock *clk);
111
112 /**
113 * clock_new:
114 * @parent: the clock parent
115 * @name: the clock object name
116 *
117 * Helper function to create a new clock and parent it to @parent. There is no
118 * need to call clock_setup_canonical_path on the returned clock as it is done
119 * by this function.
120 *
121 * @return the newly created clock
122 */
123 Clock *clock_new(Object *parent, const char *name);
124
125 /**
126 * clock_set_callback:
127 * @clk: the clock to register the callback into
128 * @cb: the callback function
129 * @opaque: the argument to the callback
130 * @events: the events the callback should be called for
131 * (logical OR of ClockEvent enum values)
132 *
133 * Register a callback called on every clock update.
134 * Note that a clock has only one callback: you cannot register
135 * different callback functions for different events.
136 */
137 void clock_set_callback(Clock *clk, ClockCallback *cb,
138 void *opaque, unsigned int events);
139
140 /**
141 * clock_clear_callback:
142 * @clk: the clock to delete the callback from
143 *
144 * Unregister the callback registered with clock_set_callback.
145 */
146 void clock_clear_callback(Clock *clk);
147
148 /**
149 * clock_set_source:
150 * @clk: the clock.
151 * @src: the source clock
152 *
153 * Setup @src as the clock source of @clk. The current @src period
154 * value is also copied to @clk and its subtree but no callback is
155 * called.
156 * Further @src update will be propagated to @clk and its subtree.
157 */
158 void clock_set_source(Clock *clk, Clock *src);
159
160 /**
161 * clock_has_source:
162 * @clk: the clock
163 *
164 * Returns true if the clock has a source clock connected to it.
165 * This is useful for devices which have input clocks which must
166 * be connected by the board/SoC code which creates them. The
167 * device code can use this to check in its realize method that
168 * the clock has been connected.
169 */
170 static inline bool clock_has_source(const Clock *clk)
171 {
172 return clk->source != NULL;
173 }
174
175 /**
176 * clock_set:
177 * @clk: the clock to initialize.
178 * @value: the clock's value, 0 means unclocked
179 *
180 * Set the local cached period value of @clk to @value.
181 *
182 * @return: true if the clock is changed.
183 */
184 bool clock_set(Clock *clk, uint64_t value);
185
186 static inline bool clock_set_hz(Clock *clk, unsigned hz)
187 {
188 return clock_set(clk, CLOCK_PERIOD_FROM_HZ(hz));
189 }
190
191 static inline bool clock_set_ns(Clock *clk, unsigned ns)
192 {
193 return clock_set(clk, CLOCK_PERIOD_FROM_NS(ns));
194 }
195
196 /**
197 * clock_propagate:
198 * @clk: the clock
199 *
200 * Propagate the clock period that has been previously configured using
201 * @clock_set(). This will update recursively all connected clocks.
202 * It is an error to call this function on a clock which has a source.
203 * Note: this function must not be called during device inititialization
204 * or migration.
205 */
206 void clock_propagate(Clock *clk);
207
208 /**
209 * clock_update:
210 * @clk: the clock to update.
211 * @value: the new clock's value, 0 means unclocked
212 *
213 * Update the @clk to the new @value. All connected clocks will be informed
214 * of this update. This is equivalent to call @clock_set() then
215 * @clock_propagate().
216 */
217 static inline void clock_update(Clock *clk, uint64_t value)
218 {
219 if (clock_set(clk, value)) {
220 clock_propagate(clk);
221 }
222 }
223
224 static inline void clock_update_hz(Clock *clk, unsigned hz)
225 {
226 clock_update(clk, CLOCK_PERIOD_FROM_HZ(hz));
227 }
228
229 static inline void clock_update_ns(Clock *clk, unsigned ns)
230 {
231 clock_update(clk, CLOCK_PERIOD_FROM_NS(ns));
232 }
233
234 /**
235 * clock_get:
236 * @clk: the clk to fetch the clock
237 *
238 * @return: the current period.
239 */
240 static inline uint64_t clock_get(const Clock *clk)
241 {
242 return clk->period;
243 }
244
245 static inline unsigned clock_get_hz(Clock *clk)
246 {
247 return CLOCK_PERIOD_TO_HZ(clock_get(clk));
248 }
249
250 /**
251 * clock_ticks_to_ns:
252 * @clk: the clock to query
253 * @ticks: number of ticks
254 *
255 * Returns the length of time in nanoseconds for this clock
256 * to tick @ticks times. Because a clock can have a period
257 * which is not a whole number of nanoseconds, it is important
258 * to use this function when calculating things like timer
259 * expiry deadlines, rather than attempting to obtain a "period
260 * in nanoseconds" value and then multiplying that by a number
261 * of ticks.
262 *
263 * The result could in theory be too large to fit in a 64-bit
264 * value if the number of ticks and the clock period are both
265 * large; to avoid overflow the result will be saturated to INT64_MAX
266 * (because this is the largest valid input to the QEMUTimer APIs).
267 * Since INT64_MAX nanoseconds is almost 300 years, anything with
268 * an expiry later than that is in the "will never happen" category
269 * and callers can reasonably not special-case the saturated result.
270 */
271 static inline uint64_t clock_ticks_to_ns(const Clock *clk, uint64_t ticks)
272 {
273 uint64_t ns_low, ns_high;
274
275 /*
276 * clk->period is the period in units of 2^-32 ns, so
277 * (clk->period * ticks) is the required length of time in those
278 * units, and we can convert to nanoseconds by multiplying by
279 * 2^32, which is the same as shifting the 128-bit multiplication
280 * result right by 32.
281 */
282 mulu64(&ns_low, &ns_high, clk->period, ticks);
283 if (ns_high & MAKE_64BIT_MASK(31, 33)) {
284 return INT64_MAX;
285 }
286 return ns_low >> 32 | ns_high << 32;
287 }
288
289 /**
290 * clock_ns_to_ticks:
291 * @clk: the clock to query
292 * @ns: duration in nanoseconds
293 *
294 * Returns the number of ticks this clock would make in the given
295 * number of nanoseconds. Because a clock can have a period which
296 * is not a whole number of nanoseconds, it is important to use this
297 * function rather than attempting to obtain a "period in nanoseconds"
298 * value and then dividing the duration by that value.
299 *
300 * If the clock is stopped (ie it has period zero), returns 0.
301 *
302 * For some inputs the result could overflow a 64-bit value (because
303 * the clock's period is short and the duration is long). In these
304 * cases we truncate the result to a 64-bit value. This is on the
305 * assumption that generally the result is going to be used to report
306 * a 32-bit or 64-bit guest register value, so wrapping either cannot
307 * happen or is the desired behaviour.
308 */
309 static inline uint64_t clock_ns_to_ticks(const Clock *clk, uint64_t ns)
310 {
311 /*
312 * ticks = duration_in_ns / period_in_ns
313 * = ns / (period / 2^32)
314 * = (ns * 2^32) / period
315 * The hi, lo inputs to divu128() are (ns << 32) as a 128 bit value.
316 */
317 uint64_t lo = ns << 32;
318 uint64_t hi = ns >> 32;
319 if (clk->period == 0) {
320 return 0;
321 }
322 /*
323 * Ignore divu128() return value as we've caught div-by-zero and don't
324 * need different behaviour for overflow.
325 */
326 divu128(&lo, &hi, clk->period);
327 return lo;
328 }
329
330 /**
331 * clock_is_enabled:
332 * @clk: a clock
333 *
334 * @return: true if the clock is running.
335 */
336 static inline bool clock_is_enabled(const Clock *clk)
337 {
338 return clock_get(clk) != 0;
339 }
340
341 /**
342 * clock_display_freq: return human-readable representation of clock frequency
343 * @clk: clock
344 *
345 * Return a string which has a human-readable representation of the
346 * clock's frequency, e.g. "33.3 MHz". This is intended for debug
347 * and display purposes.
348 *
349 * The caller is responsible for freeing the string with g_free().
350 */
351 char *clock_display_freq(Clock *clk);
352
353 #endif /* QEMU_HW_CLOCK_H */