| 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 | /* Ratio of the parent clock to run the child clocks at */ |
| 85 | uint32_t multiplier; |
| 86 | uint32_t divider; |
| 87 | |
| 88 | /* Clocks are organized in a clock tree */ |
| 89 | Clock *source; |
| 90 | QLIST_HEAD(, Clock) children; |
| 91 | QLIST_ENTRY(Clock) sibling; |
| 92 | }; |
| 93 | |
| 94 | /* |
| 95 | * vmstate description entry to be added in device vmsd. |
| 96 | */ |
| 97 | extern const VMStateDescription vmstate_clock; |
| 98 | #define VMSTATE_CLOCK(field, state) \ |
| 99 | VMSTATE_CLOCK_V(field, state, 0) |
| 100 | #define VMSTATE_CLOCK_V(field, state, version) \ |
| 101 | VMSTATE_STRUCT_POINTER_V(field, state, version, vmstate_clock, Clock) |
| 102 | #define VMSTATE_ARRAY_CLOCK(field, state, num) \ |
| 103 | VMSTATE_ARRAY_CLOCK_V(field, state, num, 0) |
| 104 | #define VMSTATE_ARRAY_CLOCK_V(field, state, num, version) \ |
| 105 | VMSTATE_ARRAY_OF_POINTER_TO_STRUCT(field, state, num, version, \ |
| 106 | vmstate_clock, Clock) |
| 107 | |
| 108 | /** |
| 109 | * clock_setup_canonical_path: |
| 110 | * @clk: clock |
| 111 | * |
| 112 | * compute the canonical path of the clock (used by log messages) |
| 113 | */ |
| 114 | void clock_setup_canonical_path(Clock *clk); |
| 115 | |
| 116 | /** |
| 117 | * clock_new: |
| 118 | * @parent: the clock parent |
| 119 | * @name: the clock object name |
| 120 | * |
| 121 | * Helper function to create a new clock and parent it to @parent. There is no |
| 122 | * need to call clock_setup_canonical_path on the returned clock as it is done |
| 123 | * by this function. |
| 124 | * |
| 125 | * @return the newly created clock |
| 126 | */ |
| 127 | Clock *clock_new(Object *parent, const char *name); |
| 128 | |
| 129 | /** |
| 130 | * clock_set_callback: |
| 131 | * @clk: the clock to register the callback into |
| 132 | * @cb: the callback function |
| 133 | * @opaque: the argument to the callback |
| 134 | * @events: the events the callback should be called for |
| 135 | * (logical OR of ClockEvent enum values) |
| 136 | * |
| 137 | * Register a callback called on every clock update. |
| 138 | * Note that a clock has only one callback: you cannot register |
| 139 | * different callback functions for different events. |
| 140 | */ |
| 141 | void clock_set_callback(Clock *clk, ClockCallback *cb, |
| 142 | void *opaque, unsigned int events); |
| 143 | |
| 144 | /** |
| 145 | * clock_set_source: |
| 146 | * @clk: the clock. |
| 147 | * @src: the source clock |
| 148 | * |
| 149 | * Setup @src as the clock source of @clk. The current @src period |
| 150 | * value is also copied to @clk and its subtree but no callback is |
| 151 | * called. |
| 152 | * Further @src update will be propagated to @clk and its subtree. |
| 153 | */ |
| 154 | void clock_set_source(Clock *clk, Clock *src); |
| 155 | |
| 156 | /** |
| 157 | * clock_has_source: |
| 158 | * @clk: the clock |
| 159 | * |
| 160 | * Returns true if the clock has a source clock connected to it. |
| 161 | * This is useful for devices which have input clocks which must |
| 162 | * be connected by the board/SoC code which creates them. The |
| 163 | * device code can use this to check in its realize method that |
| 164 | * the clock has been connected. |
| 165 | */ |
| 166 | static inline bool clock_has_source(const Clock *clk) |
| 167 | { |
| 168 | return clk->source != NULL; |
| 169 | } |
| 170 | |
| 171 | /** |
| 172 | * clock_set: |
| 173 | * @clk: the clock to initialize. |
| 174 | * @value: the clock's value, 0 means unclocked |
| 175 | * |
| 176 | * Set the local cached period value of @clk to @value. |
| 177 | * |
| 178 | * @return: true if the clock is changed. |
| 179 | */ |
| 180 | bool clock_set(Clock *clk, uint64_t value); |
| 181 | |
| 182 | static inline bool clock_set_hz(Clock *clk, unsigned hz) |
| 183 | { |
| 184 | return clock_set(clk, CLOCK_PERIOD_FROM_HZ(hz)); |
| 185 | } |
| 186 | |
| 187 | static inline bool clock_set_ns(Clock *clk, unsigned ns) |
| 188 | { |
| 189 | return clock_set(clk, CLOCK_PERIOD_FROM_NS(ns)); |
| 190 | } |
| 191 | |
| 192 | /** |
| 193 | * clock_propagate: |
| 194 | * @clk: the clock |
| 195 | * |
| 196 | * Propagate the clock period that has been previously configured using |
| 197 | * @clock_set(). This will update recursively all connected clocks. |
| 198 | * It is an error to call this function on a clock which has a source. |
| 199 | * Note: this function must not be called during device initialization |
| 200 | * or migration. |
| 201 | */ |
| 202 | void clock_propagate(Clock *clk); |
| 203 | |
| 204 | /** |
| 205 | * clock_update: |
| 206 | * @clk: the clock to update. |
| 207 | * @value: the new clock's value, 0 means unclocked |
| 208 | * |
| 209 | * Update the @clk to the new @value. All connected clocks will be informed |
| 210 | * of this update. This is equivalent to call @clock_set() then |
| 211 | * @clock_propagate(). |
| 212 | */ |
| 213 | static inline void clock_update(Clock *clk, uint64_t value) |
| 214 | { |
| 215 | if (clock_set(clk, value)) { |
| 216 | clock_propagate(clk); |
| 217 | } |
| 218 | } |
| 219 | |
| 220 | static inline void clock_update_hz(Clock *clk, unsigned hz) |
| 221 | { |
| 222 | clock_update(clk, CLOCK_PERIOD_FROM_HZ(hz)); |
| 223 | } |
| 224 | |
| 225 | static inline void clock_update_ns(Clock *clk, unsigned ns) |
| 226 | { |
| 227 | clock_update(clk, CLOCK_PERIOD_FROM_NS(ns)); |
| 228 | } |
| 229 | |
| 230 | /** |
| 231 | * clock_get: |
| 232 | * @clk: the clk to fetch the clock |
| 233 | * |
| 234 | * @return: the current period. |
| 235 | */ |
| 236 | static inline uint64_t clock_get(const Clock *clk) |
| 237 | { |
| 238 | return clk->period; |
| 239 | } |
| 240 | |
| 241 | static inline unsigned clock_get_hz(Clock *clk) |
| 242 | { |
| 243 | return CLOCK_PERIOD_TO_HZ(clock_get(clk)); |
| 244 | } |
| 245 | |
| 246 | /** |
| 247 | * clock_ticks_to_ns: |
| 248 | * @clk: the clock to query |
| 249 | * @ticks: number of ticks |
| 250 | * |
| 251 | * Returns the length of time in nanoseconds for this clock |
| 252 | * to tick @ticks times. Because a clock can have a period |
| 253 | * which is not a whole number of nanoseconds, it is important |
| 254 | * to use this function when calculating things like timer |
| 255 | * expiry deadlines, rather than attempting to obtain a "period |
| 256 | * in nanoseconds" value and then multiplying that by a number |
| 257 | * of ticks. |
| 258 | * |
| 259 | * The result could in theory be too large to fit in a 64-bit |
| 260 | * value if the number of ticks and the clock period are both |
| 261 | * large; to avoid overflow the result will be saturated to INT64_MAX |
| 262 | * (because this is the largest valid input to the QEMUTimer APIs). |
| 263 | * Since INT64_MAX nanoseconds is almost 300 years, anything with |
| 264 | * an expiry later than that is in the "will never happen" category |
| 265 | * and callers can reasonably not special-case the saturated result. |
| 266 | */ |
| 267 | static inline uint64_t clock_ticks_to_ns(const Clock *clk, uint64_t ticks) |
| 268 | { |
| 269 | uint64_t ns_low, ns_high; |
| 270 | |
| 271 | /* |
| 272 | * clk->period is the period in units of 2^-32 ns, so |
| 273 | * (clk->period * ticks) is the required length of time in those |
| 274 | * units, and we can convert to nanoseconds by multiplying by |
| 275 | * 2^32, which is the same as shifting the 128-bit multiplication |
| 276 | * result right by 32. |
| 277 | */ |
| 278 | mulu64(&ns_low, &ns_high, clk->period, ticks); |
| 279 | if (ns_high & MAKE_64BIT_MASK(31, 33)) { |
| 280 | return INT64_MAX; |
| 281 | } |
| 282 | return ns_low >> 32 | ns_high << 32; |
| 283 | } |
| 284 | |
| 285 | /** |
| 286 | * clock_ns_to_ticks: |
| 287 | * @clk: the clock to query |
| 288 | * @ns: duration in nanoseconds |
| 289 | * |
| 290 | * Returns the number of ticks this clock would make in the given |
| 291 | * number of nanoseconds. Because a clock can have a period which |
| 292 | * is not a whole number of nanoseconds, it is important to use this |
| 293 | * function rather than attempting to obtain a "period in nanoseconds" |
| 294 | * value and then dividing the duration by that value. |
| 295 | * |
| 296 | * If the clock is stopped (ie it has period zero), returns 0. |
| 297 | * |
| 298 | * For some inputs the result could overflow a 64-bit value (because |
| 299 | * the clock's period is short and the duration is long). In these |
| 300 | * cases we truncate the result to a 64-bit value. This is on the |
| 301 | * assumption that generally the result is going to be used to report |
| 302 | * a 32-bit or 64-bit guest register value, so wrapping either cannot |
| 303 | * happen or is the desired behaviour. |
| 304 | */ |
| 305 | static inline uint64_t clock_ns_to_ticks(const Clock *clk, uint64_t ns) |
| 306 | { |
| 307 | /* |
| 308 | * ticks = duration_in_ns / period_in_ns |
| 309 | * = ns / (period / 2^32) |
| 310 | * = (ns * 2^32) / period |
| 311 | * The hi, lo inputs to divu128() are (ns << 32) as a 128 bit value. |
| 312 | */ |
| 313 | uint64_t lo = ns << 32; |
| 314 | uint64_t hi = ns >> 32; |
| 315 | if (clk->period == 0) { |
| 316 | return 0; |
| 317 | } |
| 318 | |
| 319 | divu128(&lo, &hi, clk->period); |
| 320 | return lo; |
| 321 | } |
| 322 | |
| 323 | /** |
| 324 | * clock_is_enabled: |
| 325 | * @clk: a clock |
| 326 | * |
| 327 | * @return: true if the clock is running. |
| 328 | */ |
| 329 | static inline bool clock_is_enabled(const Clock *clk) |
| 330 | { |
| 331 | return clock_get(clk) != 0; |
| 332 | } |
| 333 | |
| 334 | /** |
| 335 | * clock_display_freq: return human-readable representation of clock frequency |
| 336 | * @clk: clock |
| 337 | * |
| 338 | * Return a string which has a human-readable representation of the |
| 339 | * clock's frequency, e.g. "33.3 MHz". This is intended for debug |
| 340 | * and display purposes. |
| 341 | * |
| 342 | * The caller is responsible for freeing the string with g_free(). |
| 343 | */ |
| 344 | char *clock_display_freq(Clock *clk); |
| 345 | |
| 346 | /** |
| 347 | * clock_set_mul_div: set multiplier/divider for child clocks |
| 348 | * @clk: clock |
| 349 | * @multiplier: multiplier value |
| 350 | * @divider: divider value |
| 351 | * |
| 352 | * @return: true if the clock is changed. |
| 353 | * |
| 354 | * By default, a Clock's children will all run with the same period |
| 355 | * as their parent. This function allows you to adjust the multiplier |
| 356 | * and divider used to derive the child clock frequency. |
| 357 | * For example, setting a multiplier of 2 and a divider of 3 |
| 358 | * will run child clocks with a period 2/3 of the parent clock, |
| 359 | * so if the parent clock is an 8MHz clock the children will |
| 360 | * be 12MHz. |
| 361 | * |
| 362 | * Setting the multiplier to 0 will stop the child clocks. |
| 363 | * Setting the divider to 0 is a programming error (diagnosed with |
| 364 | * an assertion failure). |
| 365 | * Setting a multiplier value that results in the child period |
| 366 | * overflowing is not diagnosed. |
| 367 | * |
| 368 | * Note that this function does not call clock_propagate(); the |
| 369 | * caller should do that if necessary. |
| 370 | */ |
| 371 | bool clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider); |
| 372 | |
| 373 | #endif /* QEMU_HW_CLOCK_H */ |