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