1/* 2 * acpi_pad.c ACPI Processor Aggregator Driver 3 * 4 * Copyright (c) 2009, Intel Corporation. 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms and conditions of the GNU General Public License, 8 * version 2, as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 13 * more details. 14 * 15 * You should have received a copy of the GNU General Public License along with 16 * this program; if not, write to the Free Software Foundation, Inc., 17 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 */ 20 21#include <linux/kernel.h> 22#include <linux/cpumask.h> 23#include <linux/module.h> 24#include <linux/init.h> 25#include <linux/types.h> 26#include <linux/kthread.h> 27#include <linux/freezer.h> 28#include <linux/cpu.h> 29#include <linux/clockchips.h> 30#include <linux/slab.h> 31#include <acpi/acpi_bus.h> 32#include <acpi/acpi_drivers.h> 33 34#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad" 35#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator" 36#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80 37static DEFINE_MUTEX(isolated_cpus_lock); 38 39#define MWAIT_SUBSTATE_MASK (0xf) 40#define MWAIT_CSTATE_MASK (0xf) 41#define MWAIT_SUBSTATE_SIZE (4) 42#define CPUID_MWAIT_LEAF (5) 43#define CPUID5_ECX_EXTENSIONS_SUPPORTED (0x1) 44#define CPUID5_ECX_INTERRUPT_BREAK (0x2) 45static unsigned long power_saving_mwait_eax; 46 47static unsigned char tsc_detected_unstable; 48static unsigned char tsc_marked_unstable; 49static unsigned char lapic_detected_unstable; 50static unsigned char lapic_marked_unstable; 51 52static void power_saving_mwait_init(void) 53{ 54 unsigned int eax, ebx, ecx, edx; 55 unsigned int highest_cstate = 0; 56 unsigned int highest_subcstate = 0; 57 int i; 58 59 if (!boot_cpu_has(X86_FEATURE_MWAIT)) 60 return; 61 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF) 62 return; 63 64 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx); 65 66 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) || 67 !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) 68 return; 69 70 edx >>= MWAIT_SUBSTATE_SIZE; 71 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) { 72 if (edx & MWAIT_SUBSTATE_MASK) { 73 highest_cstate = i; 74 highest_subcstate = edx & MWAIT_SUBSTATE_MASK; 75 } 76 } 77 power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) | 78 (highest_subcstate - 1); 79 80#if defined(CONFIG_X86) 81 switch (boot_cpu_data.x86_vendor) { 82 case X86_VENDOR_AMD: 83 case X86_VENDOR_INTEL: 84 /* 85 * AMD Fam10h TSC will tick in all 86 * C/P/S0/S1 states when this bit is set. 87 */ 88 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) 89 tsc_detected_unstable = 1; 90 if (!boot_cpu_has(X86_FEATURE_ARAT)) 91 lapic_detected_unstable = 1; 92 break; 93 default: 94 /* TSC & LAPIC could halt in idle */ 95 tsc_detected_unstable = 1; 96 lapic_detected_unstable = 1; 97 } 98#endif 99} 100 101static unsigned long cpu_weight[NR_CPUS]; 102static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1}; 103static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS); 104static void round_robin_cpu(unsigned int tsk_index) 105{ 106 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); 107 cpumask_var_t tmp; 108 int cpu; 109 unsigned long min_weight = -1; 110 unsigned long uninitialized_var(preferred_cpu); 111 112 if (!alloc_cpumask_var(&tmp, GFP_KERNEL)) 113 return; 114 115 mutex_lock(&isolated_cpus_lock); 116 cpumask_clear(tmp); 117 for_each_cpu(cpu, pad_busy_cpus) 118 cpumask_or(tmp, tmp, topology_thread_cpumask(cpu)); 119 cpumask_andnot(tmp, cpu_online_mask, tmp); 120 /* avoid HT sibilings if possible */ 121 if (cpumask_empty(tmp)) 122 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus); 123 if (cpumask_empty(tmp)) { 124 mutex_unlock(&isolated_cpus_lock); 125 return; 126 } 127 for_each_cpu(cpu, tmp) { 128 if (cpu_weight[cpu] < min_weight) { 129 min_weight = cpu_weight[cpu]; 130 preferred_cpu = cpu; 131 } 132 } 133 134 if (tsk_in_cpu[tsk_index] != -1) 135 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); 136 tsk_in_cpu[tsk_index] = preferred_cpu; 137 cpumask_set_cpu(preferred_cpu, pad_busy_cpus); 138 cpu_weight[preferred_cpu]++; 139 mutex_unlock(&isolated_cpus_lock); 140 141 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu)); 142} 143 144static void exit_round_robin(unsigned int tsk_index) 145{ 146 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); 147 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); 148 tsk_in_cpu[tsk_index] = -1; 149} 150 151static unsigned int idle_pct = 5; /* percentage */ 152static unsigned int round_robin_time = 10; /* second */ 153static int power_saving_thread(void *data) 154{ 155 struct sched_param param = {.sched_priority = 1}; 156 int do_sleep; 157 unsigned int tsk_index = (unsigned long)data; 158 u64 last_jiffies = 0; 159 160 sched_setscheduler(current, SCHED_RR, ¶m); 161 162 while (!kthread_should_stop()) { 163 int cpu; 164 u64 expire_time; 165 166 try_to_freeze(); 167 168 /* round robin to cpus */ 169 if (last_jiffies + round_robin_time * HZ < jiffies) { 170 last_jiffies = jiffies; 171 round_robin_cpu(tsk_index); 172 } 173 174 do_sleep = 0; 175 176 expire_time = jiffies + HZ * (100 - idle_pct) / 100; 177 178 while (!need_resched()) { 179 if (tsc_detected_unstable && !tsc_marked_unstable) { 180 /* TSC could halt in idle, so notify users */ 181 mark_tsc_unstable("TSC halts in idle"); 182 tsc_marked_unstable = 1; 183 } 184 if (lapic_detected_unstable && !lapic_marked_unstable) { 185 int i; 186 /* LAPIC could halt in idle, so notify users */ 187 for_each_online_cpu(i) 188 clockevents_notify( 189 CLOCK_EVT_NOTIFY_BROADCAST_ON, 190 &i); 191 lapic_marked_unstable = 1; 192 } 193 local_irq_disable(); 194 cpu = smp_processor_id(); 195 if (lapic_marked_unstable) 196 clockevents_notify( 197 CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu); 198 stop_critical_timings(); 199 200 __monitor((void *)¤t_thread_info()->flags, 0, 0); 201 smp_mb(); 202 if (!need_resched()) 203 __mwait(power_saving_mwait_eax, 1); 204 205 start_critical_timings(); 206 if (lapic_marked_unstable) 207 clockevents_notify( 208 CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu); 209 local_irq_enable(); 210 211 if (jiffies > expire_time) { 212 do_sleep = 1; 213 break; 214 } 215 } 216 217 /* 218 * current sched_rt has threshold for rt task running time. 219 * When a rt task uses 95% CPU time, the rt thread will be 220 * scheduled out for 5% CPU time to not starve other tasks. But 221 * the mechanism only works when all CPUs have RT task running, 222 * as if one CPU hasn't RT task, RT task from other CPUs will 223 * borrow CPU time from this CPU and cause RT task use > 95% 224 * CPU time. To make 'avoid starvation' work, takes a nap here. 225 */ 226 if (do_sleep) 227 schedule_timeout_killable(HZ * idle_pct / 100); 228 } 229 230 exit_round_robin(tsk_index); 231 return 0; 232} 233 234static struct task_struct *ps_tsks[NR_CPUS]; 235static unsigned int ps_tsk_num; 236static int create_power_saving_task(void) 237{ 238 int rc = -ENOMEM; 239 240 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread, 241 (void *)(unsigned long)ps_tsk_num, 242 "power_saving/%d", ps_tsk_num); 243 rc = IS_ERR(ps_tsks[ps_tsk_num]) ? PTR_ERR(ps_tsks[ps_tsk_num]) : 0; 244 if (!rc) 245 ps_tsk_num++; 246 else 247 ps_tsks[ps_tsk_num] = NULL; 248 249 return rc; 250} 251 252static void destroy_power_saving_task(void) 253{ 254 if (ps_tsk_num > 0) { 255 ps_tsk_num--; 256 kthread_stop(ps_tsks[ps_tsk_num]); 257 ps_tsks[ps_tsk_num] = NULL; 258 } 259} 260 261static void set_power_saving_task_num(unsigned int num) 262{ 263 if (num > ps_tsk_num) { 264 while (ps_tsk_num < num) { 265 if (create_power_saving_task()) 266 return; 267 } 268 } else if (num < ps_tsk_num) { 269 while (ps_tsk_num > num) 270 destroy_power_saving_task(); 271 } 272} 273 274static void acpi_pad_idle_cpus(unsigned int num_cpus) 275{ 276 get_online_cpus(); 277 278 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus()); 279 set_power_saving_task_num(num_cpus); 280 281 put_online_cpus(); 282} 283 284static uint32_t acpi_pad_idle_cpus_num(void) 285{ 286 return ps_tsk_num; 287} 288 289static ssize_t acpi_pad_rrtime_store(struct device *dev, 290 struct device_attribute *attr, const char *buf, size_t count) 291{ 292 unsigned long num; 293 if (strict_strtoul(buf, 0, &num)) 294 return -EINVAL; 295 if (num < 1 || num >= 100) 296 return -EINVAL; 297 mutex_lock(&isolated_cpus_lock); 298 round_robin_time = num; 299 mutex_unlock(&isolated_cpus_lock); 300 return count; 301} 302 303static ssize_t acpi_pad_rrtime_show(struct device *dev, 304 struct device_attribute *attr, char *buf) 305{ 306 return scnprintf(buf, PAGE_SIZE, "%d", round_robin_time); 307} 308static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR, 309 acpi_pad_rrtime_show, 310 acpi_pad_rrtime_store); 311 312static ssize_t acpi_pad_idlepct_store(struct device *dev, 313 struct device_attribute *attr, const char *buf, size_t count) 314{ 315 unsigned long num; 316 if (strict_strtoul(buf, 0, &num)) 317 return -EINVAL; 318 if (num < 1 || num >= 100) 319 return -EINVAL; 320 mutex_lock(&isolated_cpus_lock); 321 idle_pct = num; 322 mutex_unlock(&isolated_cpus_lock); 323 return count; 324} 325 326static ssize_t acpi_pad_idlepct_show(struct device *dev, 327 struct device_attribute *attr, char *buf) 328{ 329 return scnprintf(buf, PAGE_SIZE, "%d", idle_pct); 330} 331static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR, 332 acpi_pad_idlepct_show, 333 acpi_pad_idlepct_store); 334 335static ssize_t acpi_pad_idlecpus_store(struct device *dev, 336 struct device_attribute *attr, const char *buf, size_t count) 337{ 338 unsigned long num; 339 if (strict_strtoul(buf, 0, &num)) 340 return -EINVAL; 341 mutex_lock(&isolated_cpus_lock); 342 acpi_pad_idle_cpus(num); 343 mutex_unlock(&isolated_cpus_lock); 344 return count; 345} 346 347static ssize_t acpi_pad_idlecpus_show(struct device *dev, 348 struct device_attribute *attr, char *buf) 349{ 350 return cpumask_scnprintf(buf, PAGE_SIZE, 351 to_cpumask(pad_busy_cpus_bits)); 352} 353static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR, 354 acpi_pad_idlecpus_show, 355 acpi_pad_idlecpus_store); 356 357static int acpi_pad_add_sysfs(struct acpi_device *device) 358{ 359 int result; 360 361 result = device_create_file(&device->dev, &dev_attr_idlecpus); 362 if (result) 363 return -ENODEV; 364 result = device_create_file(&device->dev, &dev_attr_idlepct); 365 if (result) { 366 device_remove_file(&device->dev, &dev_attr_idlecpus); 367 return -ENODEV; 368 } 369 result = device_create_file(&device->dev, &dev_attr_rrtime); 370 if (result) { 371 device_remove_file(&device->dev, &dev_attr_idlecpus); 372 device_remove_file(&device->dev, &dev_attr_idlepct); 373 return -ENODEV; 374 } 375 return 0; 376} 377 378static void acpi_pad_remove_sysfs(struct acpi_device *device) 379{ 380 device_remove_file(&device->dev, &dev_attr_idlecpus); 381 device_remove_file(&device->dev, &dev_attr_idlepct); 382 device_remove_file(&device->dev, &dev_attr_rrtime); 383} 384 385/* 386 * Query firmware how many CPUs should be idle 387 * return -1 on failure 388 */ 389static int acpi_pad_pur(acpi_handle handle) 390{ 391 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL}; 392 union acpi_object *package; 393 int num = -1; 394 395 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer))) 396 return num; 397 398 if (!buffer.length || !buffer.pointer) 399 return num; 400 401 package = buffer.pointer; 402 403 if (package->type == ACPI_TYPE_PACKAGE && 404 package->package.count == 2 && 405 package->package.elements[0].integer.value == 1) /* rev 1 */ 406 407 num = package->package.elements[1].integer.value; 408 409 kfree(buffer.pointer); 410 return num; 411} 412 413/* Notify firmware how many CPUs are idle */ 414static void acpi_pad_ost(acpi_handle handle, int stat, 415 uint32_t idle_cpus) 416{ 417 union acpi_object params[3] = { 418 {.type = ACPI_TYPE_INTEGER,}, 419 {.type = ACPI_TYPE_INTEGER,}, 420 {.type = ACPI_TYPE_BUFFER,}, 421 }; 422 struct acpi_object_list arg_list = {3, params}; 423 424 params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY; 425 params[1].integer.value = stat; 426 params[2].buffer.length = 4; 427 params[2].buffer.pointer = (void *)&idle_cpus; 428 acpi_evaluate_object(handle, "_OST", &arg_list, NULL); 429} 430 431static void acpi_pad_handle_notify(acpi_handle handle) 432{ 433 int num_cpus; 434 uint32_t idle_cpus; 435 436 mutex_lock(&isolated_cpus_lock); 437 num_cpus = acpi_pad_pur(handle); 438 if (num_cpus < 0) { 439 mutex_unlock(&isolated_cpus_lock); 440 return; 441 } 442 acpi_pad_idle_cpus(num_cpus); 443 idle_cpus = acpi_pad_idle_cpus_num(); 444 acpi_pad_ost(handle, 0, idle_cpus); 445 mutex_unlock(&isolated_cpus_lock); 446} 447 448static void acpi_pad_notify(acpi_handle handle, u32 event, 449 void *data) 450{ 451 struct acpi_device *device = data; 452 453 switch (event) { 454 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: 455 acpi_pad_handle_notify(handle); 456 acpi_bus_generate_proc_event(device, event, 0); 457 acpi_bus_generate_netlink_event(device->pnp.device_class, 458 dev_name(&device->dev), event, 0); 459 break; 460 default: 461 printk(KERN_WARNING"Unsupported event [0x%x]\n", event); 462 break; 463 } 464} 465 466static int acpi_pad_add(struct acpi_device *device) 467{ 468 acpi_status status; 469 470 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); 471 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); 472 473 if (acpi_pad_add_sysfs(device)) 474 return -ENODEV; 475 476 status = acpi_install_notify_handler(device->handle, 477 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); 478 if (ACPI_FAILURE(status)) { 479 acpi_pad_remove_sysfs(device); 480 return -ENODEV; 481 } 482 483 return 0; 484} 485 486static int acpi_pad_remove(struct acpi_device *device, 487 int type) 488{ 489 mutex_lock(&isolated_cpus_lock); 490 acpi_pad_idle_cpus(0); 491 mutex_unlock(&isolated_cpus_lock); 492 493 acpi_remove_notify_handler(device->handle, 494 ACPI_DEVICE_NOTIFY, acpi_pad_notify); 495 acpi_pad_remove_sysfs(device); 496 return 0; 497} 498 499static const struct acpi_device_id pad_device_ids[] = { 500 {"ACPI000C", 0}, 501 {"", 0}, 502}; 503MODULE_DEVICE_TABLE(acpi, pad_device_ids); 504 505static struct acpi_driver acpi_pad_driver = { 506 .name = "processor_aggregator", 507 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, 508 .ids = pad_device_ids, 509 .ops = { 510 .add = acpi_pad_add, 511 .remove = acpi_pad_remove, 512 }, 513}; 514 515static int __init acpi_pad_init(void) 516{ 517 power_saving_mwait_init(); 518 if (power_saving_mwait_eax == 0) 519 return -EINVAL; 520 521 return acpi_bus_register_driver(&acpi_pad_driver); 522} 523 524static void __exit acpi_pad_exit(void) 525{ 526 acpi_bus_unregister_driver(&acpi_pad_driver); 527} 528 529module_init(acpi_pad_init); 530module_exit(acpi_pad_exit); 531MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>"); 532MODULE_DESCRIPTION("ACPI Processor Aggregator Driver"); 533MODULE_LICENSE("GPL"); 534