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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 | /* * Copyright (c) 1997-2010, 2012-2014 Wind River Systems, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /** * @file * @brief Microkernel idle logic * * Microkernel idle logic. Different forms of idling are performed by the idle * task, depending on how the kernel is configured. */ #include <micro_private.h> #include <nano_private.h> #include <arch/cpu.h> #include <toolchain.h> #include <sections.h> #include <microkernel.h> #include <misc/util.h> #include <drivers/system_timer.h> #if defined(CONFIG_WORKLOAD_MONITOR) static unsigned int _k_workload_slice = 0x0; static unsigned int _k_workload_ticks = 0x0; static unsigned int _k_workload_ref_time = 0x0; static unsigned int _k_workload_t0 = 0x0; static unsigned int _k_workload_t1 = 0x0; static volatile unsigned int _k_workload_n0 = 0x0; static volatile unsigned int _k_workload_n1 = 0x0; static volatile unsigned int _k_workload_i = 0x0; static volatile unsigned int _k_workload_i0 = 0x0; static volatile unsigned int _k_workload_delta = 0x0; static volatile unsigned int _k_workload_start_time = 0x0; static volatile unsigned int _k_workload_end_time = 0x0; #ifdef WL_SCALE static extern uint32_t _k_workload_scale; #endif /** * * @brief Shared code between workload calibration and monitoring * * Perform idle task "dummy work". * * This routine increments _k_workload_i and checks it against _k_workload_n1. * _k_workload_n1 is updated by the system tick handler, and both are kept * in close synchronization. * * @return N/A * */ static void workload_loop(void) { volatile int x = 87654321; volatile int y = 4; /* loop never terminates, except during calibration phase */ while (++_k_workload_i != _k_workload_n1) { unsigned int s_iCountDummyProc = 0; while (64 != s_iCountDummyProc++) { /* 64 == 2^6 */ x >>= y; x <<= y; y++; x >>= y; x <<= y; y--; } } } /** * * @brief Calibrate the workload monitoring subsystem * * Measures the time required to do a fixed amount of "dummy work", and * sets default values for the workload measuring period. * * @return N/A * */ void _k_workload_monitor_calibrate(void) { _k_workload_n0 = _k_workload_i = 0; _k_workload_n1 = 1000; _k_workload_t0 = sys_cycle_get_32(); workload_loop(); _k_workload_t1 = sys_cycle_get_32(); _k_workload_delta = _k_workload_t1 - _k_workload_t0; _k_workload_i0 = _k_workload_i; #ifdef WL_SCALE _k_workload_ref_time = (_k_workload_t1 - _k_workload_t0) >> (_k_workload_scale); #else _k_workload_ref_time = (_k_workload_t1 - _k_workload_t0) >> (4 + 6); #endif _k_workload_slice = 100; _k_workload_ticks = 100; } /** * * @brief Workload monitor tick handler * * If workload monitor is configured this routine updates the global variables * it uses to record the passage of time. * * @return N/A * */ void _k_workload_monitor_update(void) { if (--_k_workload_ticks == 0) { _k_workload_t0 = _k_workload_t1; _k_workload_t1 = sys_cycle_get_32(); _k_workload_n0 = _k_workload_n1; _k_workload_n1 = _k_workload_i - 1; _k_workload_ticks = _k_workload_slice; } } /** * * @brief Workload monitor "start idling" handler * * Records time when idle task was selected for execution by the microkernel. * * @return N/A */ void _k_workload_monitor_idle_start(void) { _k_workload_start_time = sys_cycle_get_32(); } /** * * @brief Workload monitor "end idling" handler * * Records time when idle task was no longer selected for execution by the * microkernel, and updates amount of time spent idling. * * @return N/A */ void _k_workload_monitor_idle_end(void) { _k_workload_end_time = sys_cycle_get_32(); _k_workload_i += (_k_workload_i0 * (_k_workload_end_time - _k_workload_start_time)) / _k_workload_delta; } /** * * @brief Process request to read the processor workload * * Computes workload, or uses 0 if workload monitoring is not configured. * * @return N/A */ void _k_workload_get(struct k_args *P) { unsigned int k, t; signed int iret; k = (_k_workload_i - _k_workload_n0) * _k_workload_ref_time; #ifdef WL_SCALE t = (sys_cycle_get_32() - _k_workload_t0) >> (_k_workload_scale); #else t = (sys_cycle_get_32() - _k_workload_t0) >> (4 + 6); #endif iret = MSEC_PER_SEC - k / t; /* * Due to calibration at startup, <iret> could be slightly negative. * Ensure a negative value is never returned. */ if (iret < 0) { iret = 0; } P->args.u1.rval = iret; } #else void _k_workload_get(struct k_args *P) { P->args.u1.rval = 0; } #endif /* CONFIG_WORKLOAD_MONITOR */ int task_workload_get(void) { struct k_args A; A.Comm = _K_SVC_WORKLOAD_GET; KERNEL_ENTRY(&A); return A.args.u1.rval; } void sys_workload_time_slice_set(int32_t t) { #ifdef CONFIG_WORKLOAD_MONITOR if (t < 10) { t = 10; } if (t > 1000) { t = 1000; } _k_workload_slice = t; #else ARG_UNUSED(t); #endif } unsigned char _sys_power_save_flag = 1; #if defined(CONFIG_SYS_POWER_MANAGEMENT) #include <nanokernel.h> #include <microkernel/base_api.h> #if (defined(CONFIG_SYS_POWER_LOW_POWER_STATE) || \ defined(CONFIG_SYS_POWER_DEEP_SLEEP) || \ defined(CONFIG_DEVICE_POWER_MANAGEMENT)) #include <power.h> #endif #if defined(CONFIG_TICKLESS_IDLE) #include <drivers/system_timer.h> #endif extern void nano_cpu_set_idle(int32_t ticks); #if defined(CONFIG_TICKLESS_IDLE) /* * Idle time must be this value or higher for timer to go into tickless idle * state. */ int32_t _sys_idle_threshold_ticks = CONFIG_TICKLESS_IDLE_THRESH; #endif /* CONFIG_TICKLESS_IDLE */ /** * * @brief Power management policy when kernel begins idling * * This routine implements the power management policy based on the time * until the timer expires, in system ticks. * Routine is invoked from the idle task with interrupts disabled * * @return N/A */ void _sys_power_save_idle(int32_t ticks) { #if defined(CONFIG_TICKLESS_IDLE) if ((ticks == TICKS_UNLIMITED) || ticks >= _sys_idle_threshold_ticks) { /* * Stop generating system timer interrupts until it's time for * the next scheduled microkernel timer to expire. */ _timer_idle_enter(ticks); } #endif /* CONFIG_TICKLESS_IDLE */ nano_cpu_set_idle(ticks); #if (defined(CONFIG_SYS_POWER_LOW_POWER_STATE) || \ defined(CONFIG_SYS_POWER_DEEP_SLEEP) || \ defined(CONFIG_DEVICE_POWER_MANAGEMENT)) /* * Call the suspend hook function, which checks if the system should * enter deep sleep, low power state or only suspend devices. * If the time available is too short for any PM operation then * the function returns SYS_PM_NOT_HANDLED immediately and kernel * does normal idle processing. Otherwise it will return the code * corresponding to the action taken. * * This function can just suspend devices without entering * deep sleep or cpu low power state. In this case it should return * SYS_PM_DEVICE_SUSPEND_ONLY and kernel would do normal idle * processing. * * This function is entered with interrupts disabled. If the function * returns either SYS_PM_LOW_POWER_STATE or SYS_PM_DEEP_SLEEP then * it should ensure interrupts are re-enabled before returning. * This is because the kernel does not do its own idle processing in * these cases i.e. skips nano_cpu_idle(). The kernel's idle * processing re-enables interrupts which is essential for kernel's * scheduling logic. */ if (!(_sys_soc_suspend(ticks) & (SYS_PM_DEEP_SLEEP | SYS_PM_LOW_POWER_STATE))) { nano_cpu_idle(); } #else nano_cpu_idle(); #endif } /** * * @brief Power management policy when kernel stops idling * * This routine is invoked when the kernel leaves the idle state. * Routine can be modified to wake up other devices. * The routine is invoked from interrupt thread, with interrupts disabled. * * @return N/A */ void _sys_power_save_idle_exit(int32_t ticks) { #if (defined(CONFIG_SYS_POWER_LOW_POWER_STATE) || \ defined(CONFIG_SYS_POWER_DEEP_SLEEP) || \ defined(CONFIG_DEVICE_POWER_MANAGEMENT)) /* Any idle wait based on CPU low power state will be exited by * interrupt. This function is called within that interrupt's * ISR context. _sys_soc_resume() needs to be called here * to handle exit from CPU low power states. This gives an * opportunity for device states altered in _sys_soc_suspend() * to be restored before the kernel schedules another thread. * _sys_soc_resume() is not called from here for deep sleep * exit. Deep sleep recovery happens at cold boot path. */ _sys_soc_resume(); #endif #ifdef CONFIG_TICKLESS_IDLE if ((ticks == TICKS_UNLIMITED) || ticks >= _sys_idle_threshold_ticks) { /* Resume normal periodic system timer interrupts */ _timer_idle_exit(); } #else ARG_UNUSED(ticks); #endif /* CONFIG_TICKLESS_IDLE */ } /** * * @brief Obtain number of ticks until next timer expires * * Must be called with interrupts locked to prevent the timer queues from * changing. * * @return Number of ticks until next timer expires. * */ static inline int32_t _get_next_timer_expiry(void) { uint32_t closest_deadline = (uint32_t)TICKS_UNLIMITED; if (_k_timer_list_head) { closest_deadline = _k_timer_list_head->duration; } return (int32_t)min(closest_deadline, _nano_get_earliest_deadline()); } #endif /** * * @brief Power saving when idle * * If _sys_power_save_flag is non-zero, this routine keeps the system in a low * power state whenever the kernel is idle. If it is zero, this routine will * fall through and _k_kernel_idle() will try the next idling mechanism. * * @return N/A * */ static void _power_save(void) { if (_sys_power_save_flag) { for (;;) { irq_lock(); #ifdef CONFIG_SYS_POWER_MANAGEMENT _sys_power_save_idle(_get_next_timer_expiry()); #else /* * nano_cpu_idle() is invoked here directly only if APM * is disabled. Otherwise the microkernel decides * either to invoke it or to implement advanced idle * functionality */ nano_cpu_idle(); #endif } /* * Code analyzers may complain that _power_save() uses an * infinite loop unless we indicate that this is intentional */ CODE_UNREACHABLE; } } /* Specify what work to do when idle task is "busy waiting" */ #ifdef CONFIG_WORKLOAD_MONITOR #define DO_IDLE_WORK() workload_loop() #else #define DO_IDLE_WORK() do { /* do nothing */ } while (0) #endif /** * * @brief Microkernel idle task * * If power save is on, we sleep; if power save is off, we "busy wait". * * @return N/A * */ int _k_kernel_idle(void) { _power_save(); /* never returns if power saving is enabled */ #ifdef CONFIG_BOOT_TIME_MEASUREMENT /* record timestamp when idling begins */ extern uint64_t __idle_tsc; __idle_tsc = _NanoTscRead(); #endif for (;;) { DO_IDLE_WORK(); } /* * Code analyzers may complain that _k_kernel_idle() uses an infinite * loop unless we indicate that this is intentional */ CODE_UNREACHABLE; } |