lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/kernel/time/tick-broadcast.c |
| 3 | * |
| 4 | * This file contains functions which emulate a local clock-event |
| 5 | * device via a broadcast event source. |
| 6 | * |
| 7 | * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de> |
| 8 | * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar |
| 9 | * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner |
| 10 | * |
| 11 | * This code is licenced under the GPL version 2. For details see |
| 12 | * kernel-base/COPYING. |
| 13 | */ |
| 14 | #include <linux/cpu.h> |
| 15 | #include <linux/err.h> |
| 16 | #include <linux/hrtimer.h> |
| 17 | #include <linux/interrupt.h> |
| 18 | #include <linux/percpu.h> |
| 19 | #include <linux/profile.h> |
| 20 | #include <linux/sched.h> |
| 21 | |
| 22 | #include "tick-internal.h" |
| 23 | |
| 24 | /* |
| 25 | * Broadcast support for broken x86 hardware, where the local apic |
| 26 | * timer stops in C3 state. |
| 27 | */ |
| 28 | |
| 29 | static struct tick_device tick_broadcast_device; |
| 30 | /* FIXME: Use cpumask_var_t. */ |
| 31 | static DECLARE_BITMAP(tick_broadcast_mask, NR_CPUS); |
| 32 | static DECLARE_BITMAP(tmpmask, NR_CPUS); |
| 33 | static DEFINE_RAW_SPINLOCK(tick_broadcast_lock); |
| 34 | static int tick_broadcast_force; |
| 35 | |
| 36 | #ifdef CONFIG_TICK_ONESHOT |
| 37 | static void tick_broadcast_clear_oneshot(int cpu); |
| 38 | #else |
| 39 | static inline void tick_broadcast_clear_oneshot(int cpu) { } |
| 40 | #endif |
| 41 | |
| 42 | /* |
| 43 | * Debugging: see timer_list.c |
| 44 | */ |
| 45 | struct tick_device *tick_get_broadcast_device(void) |
| 46 | { |
| 47 | return &tick_broadcast_device; |
| 48 | } |
| 49 | |
| 50 | struct cpumask *tick_get_broadcast_mask(void) |
| 51 | { |
| 52 | return to_cpumask(tick_broadcast_mask); |
| 53 | } |
| 54 | |
| 55 | /* |
| 56 | * Start the device in periodic mode |
| 57 | */ |
| 58 | static void tick_broadcast_start_periodic(struct clock_event_device *bc) |
| 59 | { |
| 60 | if (bc) |
| 61 | tick_setup_periodic(bc, 1); |
| 62 | } |
| 63 | |
| 64 | /* |
| 65 | * Check, if the device can be utilized as broadcast device: |
| 66 | */ |
| 67 | int tick_check_broadcast_device(struct clock_event_device *dev) |
| 68 | { |
| 69 | struct clock_event_device *cur = tick_broadcast_device.evtdev; |
| 70 | |
| 71 | if ((dev->features & CLOCK_EVT_FEAT_DUMMY) || |
| 72 | (tick_broadcast_device.evtdev && |
| 73 | tick_broadcast_device.evtdev->rating >= dev->rating) || |
| 74 | (dev->features & CLOCK_EVT_FEAT_C3STOP)) |
| 75 | return 0; |
| 76 | |
| 77 | clockevents_exchange_device(tick_broadcast_device.evtdev, dev); |
| 78 | if (cur) |
| 79 | cur->event_handler = clockevents_handle_noop; |
| 80 | tick_broadcast_device.evtdev = dev; |
| 81 | if (!cpumask_empty(tick_get_broadcast_mask())) |
| 82 | tick_broadcast_start_periodic(dev); |
| 83 | return 1; |
| 84 | } |
| 85 | |
| 86 | /* |
| 87 | * Check, if the device is the broadcast device |
| 88 | */ |
| 89 | int tick_is_broadcast_device(struct clock_event_device *dev) |
| 90 | { |
| 91 | return (dev && tick_broadcast_device.evtdev == dev); |
| 92 | } |
| 93 | |
| 94 | /* |
| 95 | * Check, if the device is disfunctional and a place holder, which |
| 96 | * needs to be handled by the broadcast device. |
| 97 | */ |
| 98 | int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu) |
| 99 | { |
| 100 | unsigned long flags; |
| 101 | int ret = 0; |
| 102 | |
| 103 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 104 | |
| 105 | /* |
| 106 | * Devices might be registered with both periodic and oneshot |
| 107 | * mode disabled. This signals, that the device needs to be |
| 108 | * operated from the broadcast device and is a placeholder for |
| 109 | * the cpu local device. |
| 110 | */ |
| 111 | if (!tick_device_is_functional(dev)) { |
| 112 | dev->event_handler = tick_handle_periodic; |
| 113 | cpumask_set_cpu(cpu, tick_get_broadcast_mask()); |
| 114 | tick_broadcast_start_periodic(tick_broadcast_device.evtdev); |
| 115 | ret = 1; |
| 116 | } else { |
| 117 | /* |
| 118 | * When the new device is not affected by the stop |
| 119 | * feature and the cpu is marked in the broadcast mask |
| 120 | * then clear the broadcast bit. |
| 121 | */ |
| 122 | if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) { |
| 123 | int cpu = smp_processor_id(); |
| 124 | |
| 125 | cpumask_clear_cpu(cpu, tick_get_broadcast_mask()); |
| 126 | tick_broadcast_clear_oneshot(cpu); |
| 127 | } |
| 128 | } |
| 129 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 130 | return ret; |
| 131 | } |
| 132 | |
| 133 | /* |
| 134 | * Broadcast the event to the cpus, which are set in the mask (mangled). |
| 135 | */ |
| 136 | static void tick_do_broadcast(struct cpumask *mask) |
| 137 | { |
| 138 | int cpu = smp_processor_id(); |
| 139 | struct tick_device *td; |
| 140 | |
| 141 | /* |
| 142 | * Check, if the current cpu is in the mask |
| 143 | */ |
| 144 | if (cpumask_test_cpu(cpu, mask)) { |
| 145 | cpumask_clear_cpu(cpu, mask); |
| 146 | td = &per_cpu(tick_cpu_device, cpu); |
| 147 | td->evtdev->event_handler(td->evtdev); |
| 148 | } |
| 149 | |
| 150 | if (!cpumask_empty(mask)) { |
| 151 | /* |
| 152 | * It might be necessary to actually check whether the devices |
| 153 | * have different broadcast functions. For now, just use the |
| 154 | * one of the first device. This works as long as we have this |
| 155 | * misfeature only on x86 (lapic) |
| 156 | */ |
| 157 | td = &per_cpu(tick_cpu_device, cpumask_first(mask)); |
| 158 | td->evtdev->broadcast(mask); |
| 159 | } |
| 160 | } |
| 161 | |
| 162 | /* |
| 163 | * Periodic broadcast: |
| 164 | * - invoke the broadcast handlers |
| 165 | */ |
| 166 | static void tick_do_periodic_broadcast(void) |
| 167 | { |
| 168 | raw_spin_lock(&tick_broadcast_lock); |
| 169 | |
| 170 | cpumask_and(to_cpumask(tmpmask), |
| 171 | cpu_online_mask, tick_get_broadcast_mask()); |
| 172 | tick_do_broadcast(to_cpumask(tmpmask)); |
| 173 | |
| 174 | raw_spin_unlock(&tick_broadcast_lock); |
| 175 | } |
| 176 | |
| 177 | /* |
| 178 | * Event handler for periodic broadcast ticks |
| 179 | */ |
| 180 | static void tick_handle_periodic_broadcast(struct clock_event_device *dev) |
| 181 | { |
| 182 | ktime_t next; |
| 183 | |
| 184 | tick_do_periodic_broadcast(); |
| 185 | |
| 186 | /* |
| 187 | * The device is in periodic mode. No reprogramming necessary: |
| 188 | */ |
| 189 | if (dev->mode == CLOCK_EVT_MODE_PERIODIC) |
| 190 | return; |
| 191 | |
| 192 | /* |
| 193 | * Setup the next period for devices, which do not have |
| 194 | * periodic mode. We read dev->next_event first and add to it |
| 195 | * when the event already expired. clockevents_program_event() |
| 196 | * sets dev->next_event only when the event is really |
| 197 | * programmed to the device. |
| 198 | */ |
| 199 | for (next = dev->next_event; ;) { |
| 200 | next = ktime_add(next, tick_period); |
| 201 | |
| 202 | if (!clockevents_program_event(dev, next, false)) |
| 203 | return; |
| 204 | tick_do_periodic_broadcast(); |
| 205 | } |
| 206 | } |
| 207 | |
| 208 | /* |
| 209 | * Powerstate information: The system enters/leaves a state, where |
| 210 | * affected devices might stop |
| 211 | */ |
| 212 | static void tick_do_broadcast_on_off(unsigned long *reason) |
| 213 | { |
| 214 | struct clock_event_device *bc, *dev; |
| 215 | struct tick_device *td; |
| 216 | unsigned long flags; |
| 217 | int cpu, bc_stopped; |
| 218 | |
| 219 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 220 | |
| 221 | cpu = smp_processor_id(); |
| 222 | td = &per_cpu(tick_cpu_device, cpu); |
| 223 | dev = td->evtdev; |
| 224 | bc = tick_broadcast_device.evtdev; |
| 225 | |
| 226 | /* |
| 227 | * Is the device not affected by the powerstate ? |
| 228 | */ |
| 229 | if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP)) |
| 230 | goto out; |
| 231 | |
| 232 | if (!tick_device_is_functional(dev)) |
| 233 | goto out; |
| 234 | |
| 235 | bc_stopped = cpumask_empty(tick_get_broadcast_mask()); |
| 236 | |
| 237 | switch (*reason) { |
| 238 | case CLOCK_EVT_NOTIFY_BROADCAST_ON: |
| 239 | case CLOCK_EVT_NOTIFY_BROADCAST_FORCE: |
| 240 | if (!cpumask_test_cpu(cpu, tick_get_broadcast_mask())) { |
| 241 | cpumask_set_cpu(cpu, tick_get_broadcast_mask()); |
| 242 | if (tick_broadcast_device.mode == |
| 243 | TICKDEV_MODE_PERIODIC) |
| 244 | clockevents_shutdown(dev); |
| 245 | } |
| 246 | if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_FORCE) |
| 247 | tick_broadcast_force = 1; |
| 248 | break; |
| 249 | case CLOCK_EVT_NOTIFY_BROADCAST_OFF: |
| 250 | if (!tick_broadcast_force && |
| 251 | cpumask_test_cpu(cpu, tick_get_broadcast_mask())) { |
| 252 | cpumask_clear_cpu(cpu, tick_get_broadcast_mask()); |
| 253 | if (tick_broadcast_device.mode == |
| 254 | TICKDEV_MODE_PERIODIC) |
| 255 | tick_setup_periodic(dev, 0); |
| 256 | } |
| 257 | break; |
| 258 | } |
| 259 | |
| 260 | if (cpumask_empty(tick_get_broadcast_mask())) { |
| 261 | if (!bc_stopped) |
| 262 | clockevents_shutdown(bc); |
| 263 | } else if (bc_stopped) { |
| 264 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) |
| 265 | tick_broadcast_start_periodic(bc); |
| 266 | else |
| 267 | tick_broadcast_setup_oneshot(bc); |
| 268 | } |
| 269 | out: |
| 270 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 271 | } |
| 272 | |
| 273 | /* |
| 274 | * Powerstate information: The system enters/leaves a state, where |
| 275 | * affected devices might stop. |
| 276 | */ |
| 277 | void tick_broadcast_on_off(unsigned long reason, int *oncpu) |
| 278 | { |
| 279 | if (!cpumask_test_cpu(*oncpu, cpu_online_mask)) |
| 280 | printk(KERN_ERR "tick-broadcast: ignoring broadcast for " |
| 281 | "offline CPU #%d\n", *oncpu); |
| 282 | else |
| 283 | tick_do_broadcast_on_off(&reason); |
| 284 | } |
| 285 | |
| 286 | /* |
| 287 | * Set the periodic handler depending on broadcast on/off |
| 288 | */ |
| 289 | void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast) |
| 290 | { |
| 291 | if (!broadcast) |
| 292 | dev->event_handler = tick_handle_periodic; |
| 293 | else |
| 294 | dev->event_handler = tick_handle_periodic_broadcast; |
| 295 | } |
| 296 | |
| 297 | /* |
| 298 | * Remove a CPU from broadcasting |
| 299 | */ |
| 300 | void tick_shutdown_broadcast(unsigned int *cpup) |
| 301 | { |
| 302 | struct clock_event_device *bc; |
| 303 | unsigned long flags; |
| 304 | unsigned int cpu = *cpup; |
| 305 | |
| 306 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 307 | |
| 308 | bc = tick_broadcast_device.evtdev; |
| 309 | cpumask_clear_cpu(cpu, tick_get_broadcast_mask()); |
| 310 | |
| 311 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) { |
| 312 | if (bc && cpumask_empty(tick_get_broadcast_mask())) |
| 313 | clockevents_shutdown(bc); |
| 314 | } |
| 315 | |
| 316 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 317 | } |
| 318 | |
| 319 | void tick_suspend_broadcast(void) |
| 320 | { |
| 321 | struct clock_event_device *bc; |
| 322 | unsigned long flags; |
| 323 | |
| 324 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 325 | |
| 326 | bc = tick_broadcast_device.evtdev; |
| 327 | if (bc) |
| 328 | clockevents_shutdown(bc); |
| 329 | |
| 330 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 331 | } |
| 332 | |
| 333 | int tick_resume_broadcast(void) |
| 334 | { |
| 335 | struct clock_event_device *bc; |
| 336 | unsigned long flags; |
| 337 | int broadcast = 0; |
| 338 | |
| 339 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 340 | |
| 341 | bc = tick_broadcast_device.evtdev; |
| 342 | |
| 343 | if (bc) { |
| 344 | clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME); |
| 345 | |
| 346 | switch (tick_broadcast_device.mode) { |
| 347 | case TICKDEV_MODE_PERIODIC: |
| 348 | if (!cpumask_empty(tick_get_broadcast_mask())) |
| 349 | tick_broadcast_start_periodic(bc); |
| 350 | broadcast = cpumask_test_cpu(smp_processor_id(), |
| 351 | tick_get_broadcast_mask()); |
| 352 | break; |
| 353 | case TICKDEV_MODE_ONESHOT: |
| 354 | if (!cpumask_empty(tick_get_broadcast_mask())) |
| 355 | broadcast = tick_resume_broadcast_oneshot(bc); |
| 356 | break; |
| 357 | } |
| 358 | } |
| 359 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 360 | |
| 361 | return broadcast; |
| 362 | } |
| 363 | |
| 364 | |
| 365 | #ifdef CONFIG_TICK_ONESHOT |
| 366 | |
| 367 | /* FIXME: use cpumask_var_t. */ |
| 368 | static DECLARE_BITMAP(tick_broadcast_oneshot_mask, NR_CPUS); |
| 369 | |
| 370 | /* |
| 371 | * Exposed for debugging: see timer_list.c |
| 372 | */ |
| 373 | struct cpumask *tick_get_broadcast_oneshot_mask(void) |
| 374 | { |
| 375 | return to_cpumask(tick_broadcast_oneshot_mask); |
| 376 | } |
| 377 | |
| 378 | static int tick_broadcast_set_event(ktime_t expires, int force) |
| 379 | { |
| 380 | struct clock_event_device *bc = tick_broadcast_device.evtdev; |
| 381 | |
| 382 | if (bc->mode != CLOCK_EVT_MODE_ONESHOT) |
| 383 | clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); |
| 384 | |
| 385 | return clockevents_program_event(bc, expires, force); |
| 386 | } |
| 387 | |
| 388 | int tick_resume_broadcast_oneshot(struct clock_event_device *bc) |
| 389 | { |
| 390 | clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); |
| 391 | return 0; |
| 392 | } |
| 393 | |
| 394 | /* |
| 395 | * Called from irq_enter() when idle was interrupted to reenable the |
| 396 | * per cpu device. |
| 397 | */ |
| 398 | void tick_check_oneshot_broadcast(int cpu) |
| 399 | { |
| 400 | if (cpumask_test_cpu(cpu, to_cpumask(tick_broadcast_oneshot_mask))) { |
| 401 | struct tick_device *td = &per_cpu(tick_cpu_device, cpu); |
| 402 | |
| 403 | /* |
| 404 | * We might be in the middle of switching over from |
| 405 | * periodic to oneshot. If the CPU has not yet |
| 406 | * switched over, leave the device alone. |
| 407 | */ |
| 408 | if (td->mode == TICKDEV_MODE_ONESHOT) { |
| 409 | clockevents_set_mode(td->evtdev, |
| 410 | CLOCK_EVT_MODE_ONESHOT); |
| 411 | } |
| 412 | } |
| 413 | } |
| 414 | |
| 415 | /* |
| 416 | * Handle oneshot mode broadcasting |
| 417 | */ |
| 418 | static void tick_handle_oneshot_broadcast(struct clock_event_device *dev) |
| 419 | { |
| 420 | struct tick_device *td; |
| 421 | ktime_t now, next_event; |
| 422 | int cpu; |
| 423 | |
| 424 | raw_spin_lock(&tick_broadcast_lock); |
| 425 | again: |
| 426 | dev->next_event.tv64 = KTIME_MAX; |
| 427 | next_event.tv64 = KTIME_MAX; |
| 428 | cpumask_clear(to_cpumask(tmpmask)); |
| 429 | now = ktime_get(); |
| 430 | /* Find all expired events */ |
| 431 | for_each_cpu(cpu, tick_get_broadcast_oneshot_mask()) { |
| 432 | td = &per_cpu(tick_cpu_device, cpu); |
| 433 | if (td->evtdev->next_event.tv64 <= now.tv64) |
| 434 | cpumask_set_cpu(cpu, to_cpumask(tmpmask)); |
| 435 | else if (td->evtdev->next_event.tv64 < next_event.tv64) |
| 436 | next_event.tv64 = td->evtdev->next_event.tv64; |
| 437 | } |
| 438 | |
| 439 | /* |
| 440 | * Wakeup the cpus which have an expired event. |
| 441 | */ |
| 442 | tick_do_broadcast(to_cpumask(tmpmask)); |
| 443 | |
| 444 | /* |
| 445 | * Two reasons for reprogram: |
| 446 | * |
| 447 | * - The global event did not expire any CPU local |
| 448 | * events. This happens in dyntick mode, as the maximum PIT |
| 449 | * delta is quite small. |
| 450 | * |
| 451 | * - There are pending events on sleeping CPUs which were not |
| 452 | * in the event mask |
| 453 | */ |
| 454 | if (next_event.tv64 != KTIME_MAX) { |
| 455 | /* |
| 456 | * Rearm the broadcast device. If event expired, |
| 457 | * repeat the above |
| 458 | */ |
| 459 | if (tick_broadcast_set_event(next_event, 0)) |
| 460 | goto again; |
| 461 | } |
| 462 | raw_spin_unlock(&tick_broadcast_lock); |
| 463 | } |
| 464 | |
| 465 | /* |
| 466 | * Powerstate information: The system enters/leaves a state, where |
| 467 | * affected devices might stop |
| 468 | */ |
| 469 | void tick_broadcast_oneshot_control(unsigned long reason) |
| 470 | { |
| 471 | struct clock_event_device *bc, *dev; |
| 472 | struct tick_device *td; |
| 473 | unsigned long flags; |
| 474 | int cpu; |
| 475 | |
| 476 | /* |
| 477 | * Periodic mode does not care about the enter/exit of power |
| 478 | * states |
| 479 | */ |
| 480 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) |
| 481 | return; |
| 482 | |
| 483 | /* |
| 484 | * We are called with preemtion disabled from the depth of the |
| 485 | * idle code, so we can't be moved away. |
| 486 | */ |
| 487 | cpu = smp_processor_id(); |
| 488 | td = &per_cpu(tick_cpu_device, cpu); |
| 489 | dev = td->evtdev; |
| 490 | |
| 491 | if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) |
| 492 | return; |
| 493 | |
| 494 | bc = tick_broadcast_device.evtdev; |
| 495 | |
| 496 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 497 | if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) { |
| 498 | if (!cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) { |
| 499 | cpumask_set_cpu(cpu, tick_get_broadcast_oneshot_mask()); |
| 500 | clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); |
| 501 | if (dev->next_event.tv64 < bc->next_event.tv64) |
| 502 | tick_broadcast_set_event(dev->next_event, 1); |
| 503 | } |
| 504 | } else { |
| 505 | if (cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) { |
| 506 | cpumask_clear_cpu(cpu, |
| 507 | tick_get_broadcast_oneshot_mask()); |
| 508 | clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT); |
| 509 | if (dev->next_event.tv64 != KTIME_MAX) |
| 510 | tick_program_event(dev->next_event, 1); |
| 511 | } |
| 512 | } |
| 513 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 514 | } |
| 515 | |
| 516 | /* |
| 517 | * Reset the one shot broadcast for a cpu |
| 518 | * |
| 519 | * Called with tick_broadcast_lock held |
| 520 | */ |
| 521 | static void tick_broadcast_clear_oneshot(int cpu) |
| 522 | { |
| 523 | cpumask_clear_cpu(cpu, tick_get_broadcast_oneshot_mask()); |
| 524 | } |
| 525 | |
| 526 | static void tick_broadcast_init_next_event(struct cpumask *mask, |
| 527 | ktime_t expires) |
| 528 | { |
| 529 | struct tick_device *td; |
| 530 | int cpu; |
| 531 | |
| 532 | for_each_cpu(cpu, mask) { |
| 533 | td = &per_cpu(tick_cpu_device, cpu); |
| 534 | if (td->evtdev) |
| 535 | td->evtdev->next_event = expires; |
| 536 | } |
| 537 | } |
| 538 | |
| 539 | /** |
| 540 | * tick_broadcast_setup_oneshot - setup the broadcast device |
| 541 | */ |
| 542 | void tick_broadcast_setup_oneshot(struct clock_event_device *bc) |
| 543 | { |
| 544 | int cpu = smp_processor_id(); |
| 545 | |
| 546 | /* Set it up only once ! */ |
| 547 | if (bc->event_handler != tick_handle_oneshot_broadcast) { |
| 548 | int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC; |
| 549 | |
| 550 | bc->event_handler = tick_handle_oneshot_broadcast; |
| 551 | |
| 552 | /* Take the do_timer update */ |
| 553 | tick_do_timer_cpu = cpu; |
| 554 | |
| 555 | /* |
| 556 | * We must be careful here. There might be other CPUs |
| 557 | * waiting for periodic broadcast. We need to set the |
| 558 | * oneshot_mask bits for those and program the |
| 559 | * broadcast device to fire. |
| 560 | */ |
| 561 | cpumask_copy(to_cpumask(tmpmask), tick_get_broadcast_mask()); |
| 562 | cpumask_clear_cpu(cpu, to_cpumask(tmpmask)); |
| 563 | cpumask_or(tick_get_broadcast_oneshot_mask(), |
| 564 | tick_get_broadcast_oneshot_mask(), |
| 565 | to_cpumask(tmpmask)); |
| 566 | |
| 567 | if (was_periodic && !cpumask_empty(to_cpumask(tmpmask))) { |
| 568 | clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); |
| 569 | tick_broadcast_init_next_event(to_cpumask(tmpmask), |
| 570 | tick_next_period); |
| 571 | tick_broadcast_set_event(tick_next_period, 1); |
| 572 | } else |
| 573 | bc->next_event.tv64 = KTIME_MAX; |
| 574 | } else { |
| 575 | /* |
| 576 | * The first cpu which switches to oneshot mode sets |
| 577 | * the bit for all other cpus which are in the general |
| 578 | * (periodic) broadcast mask. So the bit is set and |
| 579 | * would prevent the first broadcast enter after this |
| 580 | * to program the bc device. |
| 581 | */ |
| 582 | tick_broadcast_clear_oneshot(cpu); |
| 583 | } |
| 584 | } |
| 585 | |
| 586 | /* |
| 587 | * Select oneshot operating mode for the broadcast device |
| 588 | */ |
| 589 | void tick_broadcast_switch_to_oneshot(void) |
| 590 | { |
| 591 | struct clock_event_device *bc; |
| 592 | unsigned long flags; |
| 593 | |
| 594 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 595 | |
| 596 | tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT; |
| 597 | bc = tick_broadcast_device.evtdev; |
| 598 | if (bc) |
| 599 | tick_broadcast_setup_oneshot(bc); |
| 600 | |
| 601 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 602 | } |
| 603 | |
| 604 | |
| 605 | /* |
| 606 | * Remove a dead CPU from broadcasting |
| 607 | */ |
| 608 | void tick_shutdown_broadcast_oneshot(unsigned int *cpup) |
| 609 | { |
| 610 | unsigned long flags; |
| 611 | unsigned int cpu = *cpup; |
| 612 | |
| 613 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 614 | |
| 615 | /* |
| 616 | * Clear the broadcast mask flag for the dead cpu, but do not |
| 617 | * stop the broadcast device! |
| 618 | */ |
| 619 | cpumask_clear_cpu(cpu, tick_get_broadcast_oneshot_mask()); |
| 620 | |
| 621 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 622 | } |
| 623 | |
| 624 | /* |
| 625 | * Check, whether the broadcast device is in one shot mode |
| 626 | */ |
| 627 | int tick_broadcast_oneshot_active(void) |
| 628 | { |
| 629 | return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT; |
| 630 | } |
| 631 | |
| 632 | /* |
| 633 | * Check whether the broadcast device supports oneshot. |
| 634 | */ |
| 635 | bool tick_broadcast_oneshot_available(void) |
| 636 | { |
| 637 | struct clock_event_device *bc = tick_broadcast_device.evtdev; |
| 638 | |
| 639 | return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false; |
| 640 | } |
| 641 | |
| 642 | #endif |