1// SPDX-License-Identifier: GPL-2.0-only 2/* 3 * arch/arm/common/bL_switcher.c -- big.LITTLE cluster switcher core driver 4 * 5 * Created by: Nicolas Pitre, March 2012 6 * Copyright: (C) 2012-2013 Linaro Limited 7 */ 8 9#include <linux/atomic.h> 10#include <linux/init.h> 11#include <linux/kernel.h> 12#include <linux/module.h> 13#include <linux/sched/signal.h> 14#include <uapi/linux/sched/types.h> 15#include <linux/interrupt.h> 16#include <linux/cpu_pm.h> 17#include <linux/cpu.h> 18#include <linux/cpumask.h> 19#include <linux/kthread.h> 20#include <linux/wait.h> 21#include <linux/time.h> 22#include <linux/clockchips.h> 23#include <linux/hrtimer.h> 24#include <linux/tick.h> 25#include <linux/notifier.h> 26#include <linux/mm.h> 27#include <linux/mutex.h> 28#include <linux/smp.h> 29#include <linux/spinlock.h> 30#include <linux/string.h> 31#include <linux/sysfs.h> 32#include <linux/irqchip/arm-gic.h> 33#include <linux/moduleparam.h> 34 35#include <asm/smp_plat.h> 36#include <asm/cputype.h> 37#include <asm/suspend.h> 38#include <asm/mcpm.h> 39#include <asm/bL_switcher.h> 40 41#define CREATE_TRACE_POINTS 42#include <trace/events/power_cpu_migrate.h> 43 44 45/* 46 * Use our own MPIDR accessors as the generic ones in asm/cputype.h have 47 * __attribute_const__ and we don't want the compiler to assume any 48 * constness here as the value _does_ change along some code paths. 49 */ 50 51static int read_mpidr(void) 52{ 53 unsigned int id; 54 asm volatile ("mrc p15, 0, %0, c0, c0, 5" : "=r" (id)); 55 return id & MPIDR_HWID_BITMASK; 56} 57 58/* 59 * bL switcher core code. 60 */ 61 62static void bL_do_switch(void *_arg) 63{ 64 unsigned ib_mpidr, ib_cpu, ib_cluster; 65 long volatile handshake, **handshake_ptr = _arg; 66 67 pr_debug("%s\n", __func__); 68 69 ib_mpidr = cpu_logical_map(smp_processor_id()); 70 ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0); 71 ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1); 72 73 /* Advertise our handshake location */ 74 if (handshake_ptr) { 75 handshake = 0; 76 *handshake_ptr = &handshake; 77 } else 78 handshake = -1; 79 80 /* 81 * Our state has been saved at this point. Let's release our 82 * inbound CPU. 83 */ 84 mcpm_set_entry_vector(ib_cpu, ib_cluster, cpu_resume); 85 sev(); 86 87 /* 88 * From this point, we must assume that our counterpart CPU might 89 * have taken over in its parallel world already, as if execution 90 * just returned from cpu_suspend(). It is therefore important to 91 * be very careful not to make any change the other guy is not 92 * expecting. This is why we need stack isolation. 93 * 94 * Fancy under cover tasks could be performed here. For now 95 * we have none. 96 */ 97 98 /* 99 * Let's wait until our inbound is alive. 100 */ 101 while (!handshake) { 102 wfe(); 103 smp_mb(); 104 } 105 106 /* Let's put ourself down. */ 107 mcpm_cpu_power_down(); 108 109 /* should never get here */ 110 BUG(); 111} 112 113/* 114 * Stack isolation. To ensure 'current' remains valid, we just use another 115 * piece of our thread's stack space which should be fairly lightly used. 116 * The selected area starts just above the thread_info structure located 117 * at the very bottom of the stack, aligned to a cache line, and indexed 118 * with the cluster number. 119 */ 120#define STACK_SIZE 512 121extern void call_with_stack(void (*fn)(void *), void *arg, void *sp); 122static int bL_switchpoint(unsigned long _arg) 123{ 124 unsigned int mpidr = read_mpidr(); 125 unsigned int clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1); 126 void *stack = current_thread_info() + 1; 127 stack = PTR_ALIGN(stack, L1_CACHE_BYTES); 128 stack += clusterid * STACK_SIZE + STACK_SIZE; 129 call_with_stack(bL_do_switch, (void *)_arg, stack); 130 BUG(); 131} 132 133/* 134 * Generic switcher interface 135 */ 136 137static unsigned int bL_gic_id[MAX_CPUS_PER_CLUSTER][MAX_NR_CLUSTERS]; 138static int bL_switcher_cpu_pairing[NR_CPUS]; 139 140/* 141 * bL_switch_to - Switch to a specific cluster for the current CPU 142 * @new_cluster_id: the ID of the cluster to switch to. 143 * 144 * This function must be called on the CPU to be switched. 145 * Returns 0 on success, else a negative status code. 146 */ 147static int bL_switch_to(unsigned int new_cluster_id) 148{ 149 unsigned int mpidr, this_cpu, that_cpu; 150 unsigned int ob_mpidr, ob_cpu, ob_cluster, ib_mpidr, ib_cpu, ib_cluster; 151 struct completion inbound_alive; 152 long volatile *handshake_ptr; 153 int ipi_nr, ret; 154 155 this_cpu = smp_processor_id(); 156 ob_mpidr = read_mpidr(); 157 ob_cpu = MPIDR_AFFINITY_LEVEL(ob_mpidr, 0); 158 ob_cluster = MPIDR_AFFINITY_LEVEL(ob_mpidr, 1); 159 BUG_ON(cpu_logical_map(this_cpu) != ob_mpidr); 160 161 if (new_cluster_id == ob_cluster) 162 return 0; 163 164 that_cpu = bL_switcher_cpu_pairing[this_cpu]; 165 ib_mpidr = cpu_logical_map(that_cpu); 166 ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0); 167 ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1); 168 169 pr_debug("before switch: CPU %d MPIDR %#x -> %#x\n", 170 this_cpu, ob_mpidr, ib_mpidr); 171 172 this_cpu = smp_processor_id(); 173 174 /* Close the gate for our entry vectors */ 175 mcpm_set_entry_vector(ob_cpu, ob_cluster, NULL); 176 mcpm_set_entry_vector(ib_cpu, ib_cluster, NULL); 177 178 /* Install our "inbound alive" notifier. */ 179 init_completion(&inbound_alive); 180 ipi_nr = register_ipi_completion(&inbound_alive, this_cpu); 181 ipi_nr |= ((1 << 16) << bL_gic_id[ob_cpu][ob_cluster]); 182 mcpm_set_early_poke(ib_cpu, ib_cluster, gic_get_sgir_physaddr(), ipi_nr); 183 184 /* 185 * Let's wake up the inbound CPU now in case it requires some delay 186 * to come online, but leave it gated in our entry vector code. 187 */ 188 ret = mcpm_cpu_power_up(ib_cpu, ib_cluster); 189 if (ret) { 190 pr_err("%s: mcpm_cpu_power_up() returned %d\n", __func__, ret); 191 return ret; 192 } 193 194 /* 195 * Raise a SGI on the inbound CPU to make sure it doesn't stall 196 * in a possible WFI, such as in bL_power_down(). 197 */ 198 gic_send_sgi(bL_gic_id[ib_cpu][ib_cluster], 0); 199 200 /* 201 * Wait for the inbound to come up. This allows for other 202 * tasks to be scheduled in the mean time. 203 */ 204 wait_for_completion(&inbound_alive); 205 mcpm_set_early_poke(ib_cpu, ib_cluster, 0, 0); 206 207 /* 208 * From this point we are entering the switch critical zone 209 * and can't take any interrupts anymore. 210 */ 211 local_irq_disable(); 212 local_fiq_disable(); 213 trace_cpu_migrate_begin(ktime_get_real_ns(), ob_mpidr); 214 215 /* redirect GIC's SGIs to our counterpart */ 216 gic_migrate_target(bL_gic_id[ib_cpu][ib_cluster]); 217 218 tick_suspend_local(); 219 220 ret = cpu_pm_enter(); 221 222 /* we can not tolerate errors at this point */ 223 if (ret) 224 panic("%s: cpu_pm_enter() returned %d\n", __func__, ret); 225 226 /* Swap the physical CPUs in the logical map for this logical CPU. */ 227 cpu_logical_map(this_cpu) = ib_mpidr; 228 cpu_logical_map(that_cpu) = ob_mpidr; 229 230 /* Let's do the actual CPU switch. */ 231 ret = cpu_suspend((unsigned long)&handshake_ptr, bL_switchpoint); 232 if (ret > 0) 233 panic("%s: cpu_suspend() returned %d\n", __func__, ret); 234 235 /* We are executing on the inbound CPU at this point */ 236 mpidr = read_mpidr(); 237 pr_debug("after switch: CPU %d MPIDR %#x\n", this_cpu, mpidr); 238 BUG_ON(mpidr != ib_mpidr); 239 240 mcpm_cpu_powered_up(); 241 242 ret = cpu_pm_exit(); 243 244 tick_resume_local(); 245 246 trace_cpu_migrate_finish(ktime_get_real_ns(), ib_mpidr); 247 local_fiq_enable(); 248 local_irq_enable(); 249 250 *handshake_ptr = 1; 251 dsb_sev(); 252 253 if (ret) 254 pr_err("%s exiting with error %d\n", __func__, ret); 255 return ret; 256} 257 258struct bL_thread { 259 spinlock_t lock; 260 struct task_struct *task; 261 wait_queue_head_t wq; 262 int wanted_cluster; 263 struct completion started; 264 bL_switch_completion_handler completer; 265 void *completer_cookie; 266}; 267 268static struct bL_thread bL_threads[NR_CPUS]; 269 270static int bL_switcher_thread(void *arg) 271{ 272 struct bL_thread *t = arg; 273 int cluster; 274 bL_switch_completion_handler completer; 275 void *completer_cookie; 276 277 sched_set_fifo_low(current); 278 complete(&t->started); 279 280 do { 281 if (signal_pending(current)) 282 flush_signals(current); 283 wait_event_interruptible(t->wq, 284 t->wanted_cluster != -1 || 285 kthread_should_stop()); 286 287 spin_lock(&t->lock); 288 cluster = t->wanted_cluster; 289 completer = t->completer; 290 completer_cookie = t->completer_cookie; 291 t->wanted_cluster = -1; 292 t->completer = NULL; 293 spin_unlock(&t->lock); 294 295 if (cluster != -1) { 296 bL_switch_to(cluster); 297 298 if (completer) 299 completer(completer_cookie); 300 } 301 } while (!kthread_should_stop()); 302 303 return 0; 304} 305 306static struct task_struct *bL_switcher_thread_create(int cpu, void *arg) 307{ 308 struct task_struct *task; 309 310 task = kthread_create_on_node(bL_switcher_thread, arg, 311 cpu_to_node(cpu), "kswitcher_%d", cpu); 312 if (!IS_ERR(task)) { 313 kthread_bind(task, cpu); 314 wake_up_process(task); 315 } else 316 pr_err("%s failed for CPU %d\n", __func__, cpu); 317 return task; 318} 319 320/* 321 * bL_switch_request_cb - Switch to a specific cluster for the given CPU, 322 * with completion notification via a callback 323 * 324 * @cpu: the CPU to switch 325 * @new_cluster_id: the ID of the cluster to switch to. 326 * @completer: switch completion callback. if non-NULL, 327 * @completer(@completer_cookie) will be called on completion of 328 * the switch, in non-atomic context. 329 * @completer_cookie: opaque context argument for @completer. 330 * 331 * This function causes a cluster switch on the given CPU by waking up 332 * the appropriate switcher thread. This function may or may not return 333 * before the switch has occurred. 334 * 335 * If a @completer callback function is supplied, it will be called when 336 * the switch is complete. This can be used to determine asynchronously 337 * when the switch is complete, regardless of when bL_switch_request() 338 * returns. When @completer is supplied, no new switch request is permitted 339 * for the affected CPU until after the switch is complete, and @completer 340 * has returned. 341 */ 342int bL_switch_request_cb(unsigned int cpu, unsigned int new_cluster_id, 343 bL_switch_completion_handler completer, 344 void *completer_cookie) 345{ 346 struct bL_thread *t; 347 348 if (cpu >= ARRAY_SIZE(bL_threads)) { 349 pr_err("%s: cpu %d out of bounds\n", __func__, cpu); 350 return -EINVAL; 351 } 352 353 t = &bL_threads[cpu]; 354 355 if (IS_ERR(t->task)) 356 return PTR_ERR(t->task); 357 if (!t->task) 358 return -ESRCH; 359 360 spin_lock(&t->lock); 361 if (t->completer) { 362 spin_unlock(&t->lock); 363 return -EBUSY; 364 } 365 t->completer = completer; 366 t->completer_cookie = completer_cookie; 367 t->wanted_cluster = new_cluster_id; 368 spin_unlock(&t->lock); 369 wake_up(&t->wq); 370 return 0; 371} 372EXPORT_SYMBOL_GPL(bL_switch_request_cb); 373 374/* 375 * Activation and configuration code. 376 */ 377 378static DEFINE_MUTEX(bL_switcher_activation_lock); 379static BLOCKING_NOTIFIER_HEAD(bL_activation_notifier); 380static unsigned int bL_switcher_active; 381static unsigned int bL_switcher_cpu_original_cluster[NR_CPUS]; 382static cpumask_t bL_switcher_removed_logical_cpus; 383 384int bL_switcher_register_notifier(struct notifier_block *nb) 385{ 386 return blocking_notifier_chain_register(&bL_activation_notifier, nb); 387} 388EXPORT_SYMBOL_GPL(bL_switcher_register_notifier); 389 390int bL_switcher_unregister_notifier(struct notifier_block *nb) 391{ 392 return blocking_notifier_chain_unregister(&bL_activation_notifier, nb); 393} 394EXPORT_SYMBOL_GPL(bL_switcher_unregister_notifier); 395 396static int bL_activation_notify(unsigned long val) 397{ 398 int ret; 399 400 ret = blocking_notifier_call_chain(&bL_activation_notifier, val, NULL); 401 if (ret & NOTIFY_STOP_MASK) 402 pr_err("%s: notifier chain failed with status 0x%x\n", 403 __func__, ret); 404 return notifier_to_errno(ret); 405} 406 407static void bL_switcher_restore_cpus(void) 408{ 409 int i; 410 411 for_each_cpu(i, &bL_switcher_removed_logical_cpus) { 412 struct device *cpu_dev = get_cpu_device(i); 413 int ret = device_online(cpu_dev); 414 if (ret) 415 dev_err(cpu_dev, "switcher: unable to restore CPU\n"); 416 } 417} 418 419static int bL_switcher_halve_cpus(void) 420{ 421 int i, j, cluster_0, gic_id, ret; 422 unsigned int cpu, cluster, mask; 423 cpumask_t available_cpus; 424 425 /* First pass to validate what we have */ 426 mask = 0; 427 for_each_online_cpu(i) { 428 cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0); 429 cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); 430 if (cluster >= 2) { 431 pr_err("%s: only dual cluster systems are supported\n", __func__); 432 return -EINVAL; 433 } 434 if (WARN_ON(cpu >= MAX_CPUS_PER_CLUSTER)) 435 return -EINVAL; 436 mask |= (1 << cluster); 437 } 438 if (mask != 3) { 439 pr_err("%s: no CPU pairing possible\n", __func__); 440 return -EINVAL; 441 } 442 443 /* 444 * Now let's do the pairing. We match each CPU with another CPU 445 * from a different cluster. To get a uniform scheduling behavior 446 * without fiddling with CPU topology and compute capacity data, 447 * we'll use logical CPUs initially belonging to the same cluster. 448 */ 449 memset(bL_switcher_cpu_pairing, -1, sizeof(bL_switcher_cpu_pairing)); 450 cpumask_copy(&available_cpus, cpu_online_mask); 451 cluster_0 = -1; 452 for_each_cpu(i, &available_cpus) { 453 int match = -1; 454 cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); 455 if (cluster_0 == -1) 456 cluster_0 = cluster; 457 if (cluster != cluster_0) 458 continue; 459 cpumask_clear_cpu(i, &available_cpus); 460 for_each_cpu(j, &available_cpus) { 461 cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(j), 1); 462 /* 463 * Let's remember the last match to create "odd" 464 * pairings on purpose in order for other code not 465 * to assume any relation between physical and 466 * logical CPU numbers. 467 */ 468 if (cluster != cluster_0) 469 match = j; 470 } 471 if (match != -1) { 472 bL_switcher_cpu_pairing[i] = match; 473 cpumask_clear_cpu(match, &available_cpus); 474 pr_info("CPU%d paired with CPU%d\n", i, match); 475 } 476 } 477 478 /* 479 * Now we disable the unwanted CPUs i.e. everything that has no 480 * pairing information (that includes the pairing counterparts). 481 */ 482 cpumask_clear(&bL_switcher_removed_logical_cpus); 483 for_each_online_cpu(i) { 484 cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0); 485 cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); 486 487 /* Let's take note of the GIC ID for this CPU */ 488 gic_id = gic_get_cpu_id(i); 489 if (gic_id < 0) { 490 pr_err("%s: bad GIC ID for CPU %d\n", __func__, i); 491 bL_switcher_restore_cpus(); 492 return -EINVAL; 493 } 494 bL_gic_id[cpu][cluster] = gic_id; 495 pr_info("GIC ID for CPU %u cluster %u is %u\n", 496 cpu, cluster, gic_id); 497 498 if (bL_switcher_cpu_pairing[i] != -1) { 499 bL_switcher_cpu_original_cluster[i] = cluster; 500 continue; 501 } 502 503 ret = device_offline(get_cpu_device(i)); 504 if (ret) { 505 bL_switcher_restore_cpus(); 506 return ret; 507 } 508 cpumask_set_cpu(i, &bL_switcher_removed_logical_cpus); 509 } 510 511 return 0; 512} 513 514/* Determine the logical CPU a given physical CPU is grouped on. */ 515int bL_switcher_get_logical_index(u32 mpidr) 516{ 517 int cpu; 518 519 if (!bL_switcher_active) 520 return -EUNATCH; 521 522 mpidr &= MPIDR_HWID_BITMASK; 523 for_each_online_cpu(cpu) { 524 int pairing = bL_switcher_cpu_pairing[cpu]; 525 if (pairing == -1) 526 continue; 527 if ((mpidr == cpu_logical_map(cpu)) || 528 (mpidr == cpu_logical_map(pairing))) 529 return cpu; 530 } 531 return -EINVAL; 532} 533 534static void bL_switcher_trace_trigger_cpu(void *__always_unused info) 535{ 536 trace_cpu_migrate_current(ktime_get_real_ns(), read_mpidr()); 537} 538 539int bL_switcher_trace_trigger(void) 540{ 541 preempt_disable(); 542 543 bL_switcher_trace_trigger_cpu(NULL); 544 smp_call_function(bL_switcher_trace_trigger_cpu, NULL, true); 545 546 preempt_enable(); 547 548 return 0; 549} 550EXPORT_SYMBOL_GPL(bL_switcher_trace_trigger); 551 552static int bL_switcher_enable(void) 553{ 554 int cpu, ret; 555 556 mutex_lock(&bL_switcher_activation_lock); 557 lock_device_hotplug(); 558 if (bL_switcher_active) { 559 unlock_device_hotplug(); 560 mutex_unlock(&bL_switcher_activation_lock); 561 return 0; 562 } 563 564 pr_info("big.LITTLE switcher initializing\n"); 565 566 ret = bL_activation_notify(BL_NOTIFY_PRE_ENABLE); 567 if (ret) 568 goto error; 569 570 ret = bL_switcher_halve_cpus(); 571 if (ret) 572 goto error; 573 574 bL_switcher_trace_trigger(); 575 576 for_each_online_cpu(cpu) { 577 struct bL_thread *t = &bL_threads[cpu]; 578 spin_lock_init(&t->lock); 579 init_waitqueue_head(&t->wq); 580 init_completion(&t->started); 581 t->wanted_cluster = -1; 582 t->task = bL_switcher_thread_create(cpu, t); 583 } 584 585 bL_switcher_active = 1; 586 bL_activation_notify(BL_NOTIFY_POST_ENABLE); 587 pr_info("big.LITTLE switcher initialized\n"); 588 goto out; 589 590error: 591 pr_warn("big.LITTLE switcher initialization failed\n"); 592 bL_activation_notify(BL_NOTIFY_POST_DISABLE); 593 594out: 595 unlock_device_hotplug(); 596 mutex_unlock(&bL_switcher_activation_lock); 597 return ret; 598} 599 600#ifdef CONFIG_SYSFS 601 602static void bL_switcher_disable(void) 603{ 604 unsigned int cpu, cluster; 605 struct bL_thread *t; 606 struct task_struct *task; 607 608 mutex_lock(&bL_switcher_activation_lock); 609 lock_device_hotplug(); 610 611 if (!bL_switcher_active) 612 goto out; 613 614 if (bL_activation_notify(BL_NOTIFY_PRE_DISABLE) != 0) { 615 bL_activation_notify(BL_NOTIFY_POST_ENABLE); 616 goto out; 617 } 618 619 bL_switcher_active = 0; 620 621 /* 622 * To deactivate the switcher, we must shut down the switcher 623 * threads to prevent any other requests from being accepted. 624 * Then, if the final cluster for given logical CPU is not the 625 * same as the original one, we'll recreate a switcher thread 626 * just for the purpose of switching the CPU back without any 627 * possibility for interference from external requests. 628 */ 629 for_each_online_cpu(cpu) { 630 t = &bL_threads[cpu]; 631 task = t->task; 632 t->task = NULL; 633 if (!task || IS_ERR(task)) 634 continue; 635 kthread_stop(task); 636 /* no more switch may happen on this CPU at this point */ 637 cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1); 638 if (cluster == bL_switcher_cpu_original_cluster[cpu]) 639 continue; 640 init_completion(&t->started); 641 t->wanted_cluster = bL_switcher_cpu_original_cluster[cpu]; 642 task = bL_switcher_thread_create(cpu, t); 643 if (!IS_ERR(task)) { 644 wait_for_completion(&t->started); 645 kthread_stop(task); 646 cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1); 647 if (cluster == bL_switcher_cpu_original_cluster[cpu]) 648 continue; 649 } 650 /* If execution gets here, we're in trouble. */ 651 pr_crit("%s: unable to restore original cluster for CPU %d\n", 652 __func__, cpu); 653 pr_crit("%s: CPU %d can't be restored\n", 654 __func__, bL_switcher_cpu_pairing[cpu]); 655 cpumask_clear_cpu(bL_switcher_cpu_pairing[cpu], 656 &bL_switcher_removed_logical_cpus); 657 } 658 659 bL_switcher_restore_cpus(); 660 bL_switcher_trace_trigger(); 661 662 bL_activation_notify(BL_NOTIFY_POST_DISABLE); 663 664out: 665 unlock_device_hotplug(); 666 mutex_unlock(&bL_switcher_activation_lock); 667} 668 669static ssize_t bL_switcher_active_show(struct kobject *kobj, 670 struct kobj_attribute *attr, char *buf) 671{ 672 return sprintf(buf, "%u\n", bL_switcher_active); 673} 674 675static ssize_t bL_switcher_active_store(struct kobject *kobj, 676 struct kobj_attribute *attr, const char *buf, size_t count) 677{ 678 int ret; 679 680 switch (buf[0]) { 681 case '0': 682 bL_switcher_disable(); 683 ret = 0; 684 break; 685 case '1': 686 ret = bL_switcher_enable(); 687 break; 688 default: 689 ret = -EINVAL; 690 } 691 692 return (ret >= 0) ? count : ret; 693} 694 695static ssize_t bL_switcher_trace_trigger_store(struct kobject *kobj, 696 struct kobj_attribute *attr, const char *buf, size_t count) 697{ 698 int ret = bL_switcher_trace_trigger(); 699 700 return ret ? ret : count; 701} 702 703static struct kobj_attribute bL_switcher_active_attr = 704 __ATTR(active, 0644, bL_switcher_active_show, bL_switcher_active_store); 705 706static struct kobj_attribute bL_switcher_trace_trigger_attr = 707 __ATTR(trace_trigger, 0200, NULL, bL_switcher_trace_trigger_store); 708 709static struct attribute *bL_switcher_attrs[] = { 710 &bL_switcher_active_attr.attr, 711 &bL_switcher_trace_trigger_attr.attr, 712 NULL, 713}; 714 715static struct attribute_group bL_switcher_attr_group = { 716 .attrs = bL_switcher_attrs, 717}; 718 719static struct kobject *bL_switcher_kobj; 720 721static int __init bL_switcher_sysfs_init(void) 722{ 723 int ret; 724 725 bL_switcher_kobj = kobject_create_and_add("bL_switcher", kernel_kobj); 726 if (!bL_switcher_kobj) 727 return -ENOMEM; 728 ret = sysfs_create_group(bL_switcher_kobj, &bL_switcher_attr_group); 729 if (ret) 730 kobject_put(bL_switcher_kobj); 731 return ret; 732} 733 734#endif /* CONFIG_SYSFS */ 735 736bool bL_switcher_get_enabled(void) 737{ 738 mutex_lock(&bL_switcher_activation_lock); 739 740 return bL_switcher_active; 741} 742EXPORT_SYMBOL_GPL(bL_switcher_get_enabled); 743 744void bL_switcher_put_enabled(void) 745{ 746 mutex_unlock(&bL_switcher_activation_lock); 747} 748EXPORT_SYMBOL_GPL(bL_switcher_put_enabled); 749 750/* 751 * Veto any CPU hotplug operation on those CPUs we've removed 752 * while the switcher is active. 753 * We're just not ready to deal with that given the trickery involved. 754 */ 755static int bL_switcher_cpu_pre(unsigned int cpu) 756{ 757 int pairing; 758 759 if (!bL_switcher_active) 760 return 0; 761 762 pairing = bL_switcher_cpu_pairing[cpu]; 763 764 if (pairing == -1) 765 return -EINVAL; 766 return 0; 767} 768 769static bool no_bL_switcher; 770core_param(no_bL_switcher, no_bL_switcher, bool, 0644); 771 772static int __init bL_switcher_init(void) 773{ 774 int ret; 775 776 if (!mcpm_is_available()) 777 return -ENODEV; 778 779 cpuhp_setup_state_nocalls(CPUHP_ARM_BL_PREPARE, "arm/bl:prepare", 780 bL_switcher_cpu_pre, NULL); 781 ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "arm/bl:predown", 782 NULL, bL_switcher_cpu_pre); 783 if (ret < 0) { 784 cpuhp_remove_state_nocalls(CPUHP_ARM_BL_PREPARE); 785 pr_err("bL_switcher: Failed to allocate a hotplug state\n"); 786 return ret; 787 } 788 if (!no_bL_switcher) { 789 ret = bL_switcher_enable(); 790 if (ret) 791 return ret; 792 } 793 794#ifdef CONFIG_SYSFS 795 ret = bL_switcher_sysfs_init(); 796 if (ret) 797 pr_err("%s: unable to create sysfs entry\n", __func__); 798#endif 799 800 return 0; 801} 802 803late_initcall(bL_switcher_init); 804