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   1 /*
   2  * Copyright © 2009 Keith Packard <keithp@keithp.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  17  */
  18
  19 #include <ao.h>
  20 #include <ao_task.h>
  21 #if HAS_SAMPLE_PROFILE
  22 #include <ao_sample_profile.h>
  23 #endif
  24 #if HAS_STACK_GUARD
  25 #include <ao_mpu.h>
  26 #endif
  27
  28 #define DEBUG   0
  29
  30 #define AO_NO_TASK_INDEX        0xff
  31
  32 __xdata struct ao_task * __xdata ao_tasks[AO_NUM_TASKS];
  33 __data uint8_t ao_num_tasks;
  34 __xdata struct ao_task *__data ao_cur_task;
  35
  36 #if !HAS_TASK_QUEUE
  37 static __data uint8_t ao_cur_task_index;
  38 #endif
  39
  40 #ifdef ao_arch_task_globals
  41 ao_arch_task_globals
  42 #endif
  43
  44 #define AO_CHECK_STACK  0
  45
  46 #if AO_CHECK_STACK
  47 static uint8_t  in_yield;
  48
  49 static inline void ao_check_stack(void) {
  50         uint8_t q;
  51         if (!in_yield && ao_cur_task && &q < &ao_cur_task->stack[0])
  52                 ao_panic(AO_PANIC_STACK);
  53 }
  54 #else
  55 #define ao_check_stack()
  56 #endif
  57
  58 #if DEBUG
  59 #define ao_task_irq_check()     ao_arch_irq_check()
  60 #else
  61 #define ao_task_irq_check()
  62 #endif
  63
  64 #if HAS_TASK_QUEUE
  65
  66 #define SLEEP_HASH_SIZE 17
  67
  68 static struct ao_list   run_queue;
  69 static struct ao_list   alarm_queue;
  70 static struct ao_list   sleep_queue[SLEEP_HASH_SIZE];
  71
  72 static void
  73 ao_task_to_run_queue(struct ao_task *task)
  74 {
  75         ao_task_irq_check();
  76         ao_list_del(&task->queue);
  77         ao_list_append(&task->queue, &run_queue);
  78 }
  79
  80 static struct ao_list *
  81 ao_task_sleep_queue(void *wchan)
  82 {
  83         return &sleep_queue[(uintptr_t) wchan % SLEEP_HASH_SIZE];
  84 }
  85
  86 static void
  87 ao_task_to_sleep_queue(struct ao_task *task, void *wchan)
  88 {
  89         ao_task_irq_check();
  90         ao_list_del(&task->queue);
  91         ao_list_append(&task->queue, ao_task_sleep_queue(wchan));
  92 }
  93
  94 #if DEBUG
  95 static void
  96 ao_task_validate_alarm_queue(void)
  97 {
  98         struct ao_task  *alarm, *prev = NULL;
  99         int             i;
 100
 101         if (ao_list_is_empty(&alarm_queue))
 102                 return;
 103         ao_list_for_each_entry(alarm, &alarm_queue, struct ao_task, alarm_queue) {
 104                 if (prev) {
 105                         if ((int16_t) (alarm->alarm - prev->alarm) < 0) {
 106                                 ao_panic(1);
 107                         }
 108                 }
 109                 prev = alarm;
 110         }
 111         for (i = 0; i < ao_num_tasks; i++) {
 112                 alarm = ao_tasks[i];
 113                 if (alarm->alarm) {
 114                         if (ao_list_is_empty(&alarm->alarm_queue))
 115                                 ao_panic(2);
 116                 } else {
 117                         if (!ao_list_is_empty(&alarm->alarm_queue))
 118                                 ao_panic(3);
 119                 }
 120         }
 121         if (ao_task_alarm_tick != ao_list_first_entry(&alarm_queue, struct ao_task, alarm_queue)->alarm)
 122                 ao_panic(4);
 123 }
 124 #else
 125 #define ao_task_validate_alarm_queue()
 126 #endif
 127
 128 uint16_t        ao_task_alarm_tick;
 129
 130 static void
 131 ao_task_to_alarm_queue(struct ao_task *task)
 132 {
 133         struct ao_task  *alarm;
 134         ao_task_irq_check();
 135         ao_list_for_each_entry(alarm, &alarm_queue, struct ao_task, alarm_queue) {
 136                 if ((int16_t) (alarm->alarm - task->alarm) >= 0) {
 137                         ao_list_insert(&task->alarm_queue, alarm->alarm_queue.prev);
 138                         ao_task_alarm_tick = ao_list_first_entry(&alarm_queue, struct ao_task, alarm_queue)->alarm;
 139                         ao_task_validate_alarm_queue();
 140                         return;
 141                 }
 142         }
 143         ao_list_append(&task->alarm_queue, &alarm_queue);
 144         ao_task_alarm_tick = ao_list_first_entry(&alarm_queue, struct ao_task, alarm_queue)->alarm;
 145         ao_task_validate_alarm_queue();
 146 }
 147
 148 static void
 149 ao_task_from_alarm_queue(struct ao_task *task)
 150 {
 151         ao_task_irq_check();
 152         ao_list_del(&task->alarm_queue);
 153         if (ao_list_is_empty(&alarm_queue))
 154                 ao_task_alarm_tick = 0;
 155         else
 156                 ao_task_alarm_tick = ao_list_first_entry(&alarm_queue, struct ao_task, alarm_queue)->alarm;
 157         ao_task_validate_alarm_queue();
 158 }
 159
 160 static void
 161 ao_task_init_queue(struct ao_task *task)
 162 {
 163         ao_list_init(&task->queue);
 164         ao_list_init(&task->alarm_queue);
 165 }
 166
 167 static void
 168 ao_task_exit_queue(struct ao_task *task)
 169 {
 170         ao_task_irq_check();
 171         ao_list_del(&task->queue);
 172         ao_list_del(&task->alarm_queue);
 173 }
 174
 175 void
 176 ao_task_check_alarm(uint16_t tick)
 177 {
 178         struct ao_task  *alarm, *next;
 179
 180         ao_arch_critical(
 181                 ao_list_for_each_entry_safe(alarm, next, &alarm_queue, struct ao_task, alarm_queue) {
 182                         if ((int16_t) (tick - alarm->alarm) < 0)
 183                                 break;
 184                         alarm->alarm = 0;
 185                         ao_task_from_alarm_queue(alarm);
 186                         ao_task_to_run_queue(alarm);
 187                 });
 188 }
 189
 190 void
 191 ao_task_init(void)
 192 {
 193         uint8_t i;
 194         ao_list_init(&run_queue);
 195         ao_list_init(&alarm_queue);
 196         ao_task_alarm_tick = 0;
 197         for (i = 0; i < SLEEP_HASH_SIZE; i++)
 198                 ao_list_init(&sleep_queue[i]);
 199 }
 200
 201 #if DEBUG
 202 static uint8_t
 203 ao_task_validate_queue(struct ao_task *task)
 204 {
 205         uint32_t flags;
 206         struct ao_task *m;
 207         uint8_t ret = 0;
 208         struct ao_list *queue;
 209
 210         flags = ao_arch_irqsave();
 211         if (task->wchan) {
 212                 queue = ao_task_sleep_queue(task->wchan);
 213                 ret |= 2;
 214         } else {
 215                 queue = &run_queue;
 216                 ret |= 4;
 217         }
 218         ao_list_for_each_entry(m, queue, struct ao_task, queue) {
 219                 if (m == task) {
 220                         ret |= 1;
 221                         break;
 222                 }
 223         }
 224         ao_arch_irqrestore(flags);
 225         return ret;
 226 }
 227
 228 static uint8_t
 229 ao_task_validate_alarm(struct ao_task *task)
 230 {
 231         uint32_t        flags;
 232         struct ao_task  *m;
 233         uint8_t         ret = 0;
 234
 235         flags = ao_arch_irqsave();
 236         if (task->alarm == 0)
 237                 return 0xff;
 238         ao_list_for_each_entry(m, &alarm_queue, struct ao_task, alarm_queue) {
 239                 if (m == task)
 240                         ret |= 1;
 241                 else {
 242                         if (!(ret&1)) {
 243                                 if ((int16_t) (m->alarm - task->alarm) > 0)
 244                                         ret |= 2;
 245                         } else {
 246                                 if ((int16_t) (task->alarm - m->alarm) > 0)
 247                                         ret |= 4;
 248                         }
 249                 }
 250         }
 251         ao_arch_irqrestore(flags);
 252         return ret;
 253 }
 254
 255
 256 static void
 257 ao_task_validate(void)
 258 {
 259         uint8_t         i;
 260         struct ao_task  *task;
 261         uint8_t         ret;
 262
 263         for (i = 0; i < ao_num_tasks; i++) {
 264                 task = ao_tasks[i];
 265                 ret = ao_task_validate_queue(task);
 266                 if (!(ret & 1)) {
 267                         if (ret & 2)
 268                                 printf ("sleeping task not on sleep queue %s %08x\n",
 269                                         task->name, task->wchan);
 270                         else
 271                                 printf ("running task not on run queue %s\n",
 272                                         task->name);
 273                 }
 274                 ret = ao_task_validate_alarm(task);
 275                 if (ret != 0xff) {
 276                         if (!(ret & 1))
 277                                 printf ("alarm task not on alarm queue %s %d\n",
 278                                         task->name, task->alarm);
 279                         if (ret & 2)
 280                                 printf ("alarm queue has sooner entries after %s %d\n",
 281                                         task->name, task->alarm);
 282                         if (ret & 4)
 283                                 printf ("alarm queue has later entries before %s %d\n",
 284                                         task->name, task->alarm);
 285                 }
 286         }
 287 }
 288 #endif /* DEBUG */
 289
 290 #endif /* HAS_TASK_QUEUE */
 291
 292 void
 293 ao_add_task(__xdata struct ao_task * task, void (*start)(void), __code char *name) __reentrant
 294 {
 295         uint8_t task_id;
 296         uint8_t t;
 297         if (ao_num_tasks == AO_NUM_TASKS)
 298                 ao_panic(AO_PANIC_NO_TASK);
 299         for (task_id = 1; task_id != 0; task_id++) {
 300                 for (t = 0; t < ao_num_tasks; t++)
 301                         if (ao_tasks[t]->task_id == task_id)
 302                                 break;
 303                 if (t == ao_num_tasks)
 304                         break;
 305         }
 306         task->task_id = task_id;
 307         task->name = name;
 308         task->wchan = NULL;
 309         /*
 310          * Construct a stack frame so that it will 'return'
 311          * to the start of the task
 312          */
 313         ao_arch_init_stack(task, start);
 314         ao_arch_critical(
 315 #if HAS_TASK_QUEUE
 316                 ao_task_init_queue(task);
 317                 ao_task_to_run_queue(task);
 318 #endif
 319                 ao_tasks[ao_num_tasks] = task;
 320                 ao_num_tasks++;
 321                 );
 322 }
 323
 324 __data uint8_t  ao_task_minimize_latency;
 325
 326 /* Task switching function. This must not use any stack variables */
 327 void
 328 ao_yield(void) ao_arch_naked_define
 329 {
 330         ao_arch_save_regs();
 331
 332 #if HAS_TASK_QUEUE
 333         if (ao_cur_task == NULL)
 334                 ao_cur_task = ao_tasks[ao_num_tasks-1];
 335 #else
 336         if (ao_cur_task_index == AO_NO_TASK_INDEX)
 337                 ao_cur_task_index = ao_num_tasks-1;
 338 #endif
 339         else
 340         {
 341 #if HAS_SAMPLE_PROFILE
 342                 uint16_t        tick = ao_sample_profile_timer_value();
 343                 uint16_t        run = tick - ao_cur_task->start;
 344                 if (run > ao_cur_task->max_run)
 345                         ao_cur_task->max_run = run;
 346                 ++ao_cur_task->yields;
 347 #endif
 348                 ao_arch_save_stack();
 349         }
 350
 351         ao_arch_isr_stack();
 352 #if !HAS_TASK_QUEUE
 353         if (ao_task_minimize_latency)
 354                 ao_arch_release_interrupts();
 355         else
 356 #endif
 357                 ao_arch_block_interrupts();
 358
 359 #if AO_CHECK_STACK
 360         in_yield = 1;
 361 #endif
 362         /* Find a task to run. If there isn't any runnable task,
 363          * this loop will run forever, which is just fine
 364          */
 365 #if HAS_TASK_QUEUE
 366         /* If the current task is running, move it to the
 367          * end of the queue to allow other tasks a chance
 368          */
 369         if (ao_cur_task->wchan == NULL)
 370                 ao_task_to_run_queue(ao_cur_task);
 371         for (;;) {
 372                 ao_arch_memory_barrier();
 373                 if (!ao_list_is_empty(&run_queue))
 374                         break;
 375                 /* Wait for interrupts when there's nothing ready */
 376                 ao_arch_wait_interrupt();
 377         }
 378         ao_cur_task = ao_list_first_entry(&run_queue, struct ao_task, queue);
 379 #else
 380         {
 381                 __pdata uint8_t ao_last_task_index = ao_cur_task_index;
 382                 for (;;) {
 383                         ++ao_cur_task_index;
 384                         if (ao_cur_task_index == ao_num_tasks)
 385                                 ao_cur_task_index = 0;
 386
 387                         ao_cur_task = ao_tasks[ao_cur_task_index];
 388
 389                         /* Check for ready task */
 390                         if (ao_cur_task->wchan == NULL)
 391                                 break;
 392
 393                         /* Check if the alarm is set for a time which has passed */
 394                         if (ao_cur_task->alarm &&
 395                             (int16_t) (ao_time() - ao_cur_task->alarm) >= 0)
 396                                 break;
 397
 398                         /* Wait for interrupts when there's nothing ready */
 399                         if (ao_cur_task_index == ao_last_task_index && !ao_task_minimize_latency)
 400                                 ao_arch_wait_interrupt();
 401                 }
 402         }
 403 #endif
 404 #if HAS_SAMPLE_PROFILE
 405         ao_cur_task->start = ao_sample_profile_timer_value();
 406 #endif
 407 #if HAS_STACK_GUARD
 408         ao_mpu_stack_guard(ao_cur_task->stack);
 409 #endif
 410 #if AO_CHECK_STACK
 411         in_yield = 0;
 412 #endif
 413         ao_arch_restore_stack();
 414 }
 415
 416 uint8_t
 417 ao_sleep(__xdata void *wchan)
 418 {
 419 #if HAS_TASK_QUEUE
 420         uint32_t flags;
 421         flags = ao_arch_irqsave();
 422 #endif
 423         ao_cur_task->wchan = wchan;
 424 #if HAS_TASK_QUEUE
 425         ao_task_to_sleep_queue(ao_cur_task, wchan);
 426         ao_arch_irqrestore(flags);
 427 #endif
 428         ao_yield();
 429         if (ao_cur_task->wchan) {
 430                 ao_cur_task->wchan = NULL;
 431                 ao_cur_task->alarm = 0;
 432                 return 1;
 433         }
 434         return 0;
 435 }
 436
 437 void
 438 ao_wakeup(__xdata void *wchan) __reentrant
 439 {
 440         ao_validate_cur_stack();
 441 #if HAS_TASK_QUEUE
 442         struct ao_task  *sleep, *next;
 443         struct ao_list  *sleep_queue;
 444         uint32_t        flags;
 445
 446         if (ao_num_tasks == 0)
 447                 return;
 448         sleep_queue = ao_task_sleep_queue(wchan);
 449         flags = ao_arch_irqsave();
 450         ao_list_for_each_entry_safe(sleep, next, sleep_queue, struct ao_task, queue) {
 451                 if (sleep->wchan == wchan) {
 452                         sleep->wchan = NULL;
 453                         ao_task_to_run_queue(sleep);
 454                 }
 455         }
 456         ao_arch_irqrestore(flags);
 457 #else
 458         {
 459         uint8_t i;
 460         for (i = 0; i < ao_num_tasks; i++)
 461                 if (ao_tasks[i]->wchan == wchan)
 462                         ao_tasks[i]->wchan = NULL;
 463         }
 464 #endif
 465         ao_check_stack();
 466 }
 467
 468 uint8_t
 469 ao_sleep_for(__xdata void *wchan, uint16_t timeout)
 470 {
 471         uint8_t ret;
 472         if (timeout) {
 473 #if HAS_TASK_QUEUE
 474                 uint32_t flags;
 475                 flags = ao_arch_irqsave();
 476 #endif
 477                 /* Make sure we sleep *at least* delay ticks, which means adding
 478                  * one to account for the fact that we may be close to the next tick
 479                  */
 480                 if (!(ao_cur_task->alarm = ao_time() + timeout + 1))
 481                         ao_cur_task->alarm = 1;
 482 #if HAS_TASK_QUEUE
 483                 ao_task_to_alarm_queue(ao_cur_task);
 484                 ao_arch_irqrestore(flags);
 485 #endif
 486         }
 487         ret = ao_sleep(wchan);
 488         if (timeout) {
 489 #if HAS_TASK_QUEUE
 490                 uint32_t flags;
 491
 492                 flags = ao_arch_irqsave();
 493 #endif
 494                 ao_cur_task->alarm = 0;
 495 #if HAS_TASK_QUEUE
 496                 ao_task_from_alarm_queue(ao_cur_task);
 497                 ao_arch_irqrestore(flags);
 498 #endif
 499         }
 500         return ret;
 501 }
 502
 503 static __xdata uint8_t ao_forever;
 504
 505 void
 506 ao_delay(uint16_t ticks)
 507 {
 508         if (!ticks)
 509                 ticks = 1;
 510         ao_sleep_for(&ao_forever, ticks);
 511 }
 512
 513 void
 514 ao_exit(void)
 515 {
 516         uint8_t i;
 517         ao_arch_block_interrupts();
 518         ao_num_tasks--;
 519 #if HAS_TASK_QUEUE
 520         for (i = 0; i < ao_num_tasks; i++)
 521                 if (ao_tasks[i] == ao_cur_task)
 522                         break;
 523         ao_task_exit_queue(ao_cur_task);
 524 #else
 525         i = ao_cur_task_index;
 526         ao_cur_task_index = AO_NO_TASK_INDEX;
 527 #endif
 528         for (; i < ao_num_tasks; i++)
 529                 ao_tasks[i] = ao_tasks[i+1];
 530         ao_cur_task = NULL;
 531         ao_yield();
 532         /* we'll never get back here */
 533 }
 534
 535 #if HAS_TASK_INFO
 536 void
 537 ao_task_info(void)
 538 {
 539         uint8_t         i;
 540         __xdata struct ao_task *task;
 541         uint16_t        now = ao_time();
 542
 543         for (i = 0; i < ao_num_tasks; i++) {
 544                 task = ao_tasks[i];
 545                 printf("%2d: wchan %08x alarm %5d %s\n",
 546                        task->task_id,
 547                        (int) task->wchan,
 548                        task->alarm ? (int16_t) (task->alarm - now) : 9999,
 549                        task->name);
 550         }
 551 #if HAS_TASK_QUEUE && DEBUG
 552         ao_task_validate();
 553 #endif
 554 }
 555 #endif
 556
 557 void
 558 ao_start_scheduler(void)
 559 {
 560 #if !HAS_TASK_QUEUE
 561         ao_cur_task_index = AO_NO_TASK_INDEX;
 562 #endif
 563         ao_cur_task = NULL;
 564 #if HAS_ARCH_START_SCHEDULER
 565         ao_arch_start_scheduler();
 566 #endif
 567         ao_yield();
 568 }