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; 104 unsigned long uninitialized_var(preferred_cpu); 105 106 if (!alloc_cpumask_var(&tmp, GFP_KERNEL)) 107 return; 108 109 mutex_lock(&isolated_cpus_lock); 110 cpumask_clear(tmp); 111 for_each_cpu(cpu, pad_busy_cpus) 112 cpumask_or(tmp, tmp, topology_thread_cpumask(cpu)); 113 cpumask_andnot(tmp, cpu_online_mask, tmp); 114 /* avoid HT sibilings if possible */ 115 if (cpumask_empty(tmp)) 116 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus); 117 if (cpumask_empty(tmp)) { 118 mutex_unlock(&isolated_cpus_lock); 119 return; 120 } 121 for_each_cpu(cpu, tmp) { 122 if (cpu_weight[cpu] < min_weight) { 123 min_weight = cpu_weight[cpu]; 124 preferred_cpu = cpu; 125 } 126 } 127 128 if (tsk_in_cpu[tsk_index] != -1) 129 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); 130 tsk_in_cpu[tsk_index] = preferred_cpu; 131 cpumask_set_cpu(preferred_cpu, pad_busy_cpus); 132 cpu_weight[preferred_cpu]++; 133 mutex_unlock(&isolated_cpus_lock); 134 135 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu)); 136 } 137 138 static void exit_round_robin(unsigned int tsk_index) 139 { 140 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); 141 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); 142 tsk_in_cpu[tsk_index] = -1; 143 } 144 145 static unsigned int idle_pct = 5; /* percentage */ 146 static unsigned int round_robin_time = 10; /* second */ 147 static int power_saving_thread(void *data) 148 { 149 struct sched_param param = {.sched_priority = 1}; 150 int do_sleep; 151 unsigned int tsk_index = (unsigned long)data; 152 u64 last_jiffies = 0; 153 154 sched_setscheduler(current, SCHED_RR, ¶m); 155 156 while (!kthread_should_stop()) { 157 int cpu; 158 u64 expire_time; 159 160 try_to_freeze(); 161 162 /* round robin to cpus */ 163 if (last_jiffies + round_robin_time * HZ < jiffies) { 164 last_jiffies = jiffies; 165 round_robin_cpu(tsk_index); 166 } 167 168 do_sleep = 0; 169 170 current_thread_info()->status &= ~TS_POLLING; 171 /* 172 * TS_POLLING-cleared state must be visible before we test 173 * NEED_RESCHED: 174 */ 175 smp_mb(); 176 177 expire_time = jiffies + HZ * (100 - idle_pct) / 100; 178 179 while (!need_resched()) { 180 local_irq_disable(); 181 cpu = smp_processor_id(); 182 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, 183 &cpu); 184 stop_critical_timings(); 185 186 __monitor((void *)¤t_thread_info()->flags, 0, 0); 187 smp_mb(); 188 if (!need_resched()) 189 __mwait(power_saving_mwait_eax, 1); 190 191 start_critical_timings(); 192 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, 193 &cpu); 194 local_irq_enable(); 195 196 if (jiffies > expire_time) { 197 do_sleep = 1; 198 break; 199 } 200 } 201 202 current_thread_info()->status |= TS_POLLING; 203 204 /* 205 * current sched_rt has threshold for rt task running time. 206 * When a rt task uses 95% CPU time, the rt thread will be 207 * scheduled out for 5% CPU time to not starve other tasks. But 208 * the mechanism only works when all CPUs have RT task running, 209 * as if one CPU hasn't RT task, RT task from other CPUs will 210 * borrow CPU time from this CPU and cause RT task use > 95% 211 * CPU time. To make 'avoid starvation' work, takes a nap here. 212 */ 213 if (do_sleep) 214 schedule_timeout_killable(HZ * idle_pct / 100); 215 } 216 217 exit_round_robin(tsk_index); 218 return 0; 219 } 220 221 static struct task_struct *ps_tsks[NR_CPUS]; 222 static unsigned int ps_tsk_num; 223 static int create_power_saving_task(void) 224 { 225 int rc = -ENOMEM; 226 227 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread, 228 (void *)(unsigned long)ps_tsk_num, 229 "power_saving/%d", ps_tsk_num); 230 rc = IS_ERR(ps_tsks[ps_tsk_num]) ? PTR_ERR(ps_tsks[ps_tsk_num]) : 0; 231 if (!rc) 232 ps_tsk_num++; 233 else 234 ps_tsks[ps_tsk_num] = NULL; 235 236 return rc; 237 } 238 239 static void destroy_power_saving_task(void) 240 { 241 if (ps_tsk_num > 0) { 242 ps_tsk_num--; 243 kthread_stop(ps_tsks[ps_tsk_num]); 244 ps_tsks[ps_tsk_num] = NULL; 245 } 246 } 247 248 static void set_power_saving_task_num(unsigned int num) 249 { 250 if (num > ps_tsk_num) { 251 while (ps_tsk_num < num) { 252 if (create_power_saving_task()) 253 return; 254 } 255 } else if (num < ps_tsk_num) { 256 while (ps_tsk_num > num) 257 destroy_power_saving_task(); 258 } 259 } 260 261 static void acpi_pad_idle_cpus(unsigned int num_cpus) 262 { 263 get_online_cpus(); 264 265 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus()); 266 set_power_saving_task_num(num_cpus); 267 268 put_online_cpus(); 269 } 270 271 static uint32_t acpi_pad_idle_cpus_num(void) 272 { 273 return ps_tsk_num; 274 } 275 276 static ssize_t acpi_pad_rrtime_store(struct device *dev, 277 struct device_attribute *attr, const char *buf, size_t count) 278 { 279 unsigned long num; 280 if (strict_strtoul(buf, 0, &num)) 281 return -EINVAL; 282 if (num < 1 || num >= 100) 283 return -EINVAL; 284 mutex_lock(&isolated_cpus_lock); 285 round_robin_time = num; 286 mutex_unlock(&isolated_cpus_lock); 287 return count; 288 } 289 290 static ssize_t acpi_pad_rrtime_show(struct device *dev, 291 struct device_attribute *attr, char *buf) 292 { 293 return scnprintf(buf, PAGE_SIZE, "%d", round_robin_time); 294 } 295 static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR, 296 acpi_pad_rrtime_show, 297 acpi_pad_rrtime_store); 298 299 static ssize_t acpi_pad_idlepct_store(struct device *dev, 300 struct device_attribute *attr, const char *buf, size_t count) 301 { 302 unsigned long num; 303 if (strict_strtoul(buf, 0, &num)) 304 return -EINVAL; 305 if (num < 1 || num >= 100) 306 return -EINVAL; 307 mutex_lock(&isolated_cpus_lock); 308 idle_pct = num; 309 mutex_unlock(&isolated_cpus_lock); 310 return count; 311 } 312 313 static ssize_t acpi_pad_idlepct_show(struct device *dev, 314 struct device_attribute *attr, char *buf) 315 { 316 return scnprintf(buf, PAGE_SIZE, "%d", idle_pct); 317 } 318 static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR, 319 acpi_pad_idlepct_show, 320 acpi_pad_idlepct_store); 321 322 static ssize_t acpi_pad_idlecpus_store(struct device *dev, 323 struct device_attribute *attr, const char *buf, size_t count) 324 { 325 unsigned long num; 326 if (strict_strtoul(buf, 0, &num)) 327 return -EINVAL; 328 mutex_lock(&isolated_cpus_lock); 329 acpi_pad_idle_cpus(num); 330 mutex_unlock(&isolated_cpus_lock); 331 return count; 332 } 333 334 static ssize_t acpi_pad_idlecpus_show(struct device *dev, 335 struct device_attribute *attr, char *buf) 336 { 337 return cpumask_scnprintf(buf, PAGE_SIZE, 338 to_cpumask(pad_busy_cpus_bits)); 339 } 340 static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR, 341 acpi_pad_idlecpus_show, 342 acpi_pad_idlecpus_store); 343 344 static int acpi_pad_add_sysfs(struct acpi_device *device) 345 { 346 int result; 347 348 result = device_create_file(&device->dev, &dev_attr_idlecpus); 349 if (result) 350 return -ENODEV; 351 result = device_create_file(&device->dev, &dev_attr_idlepct); 352 if (result) { 353 device_remove_file(&device->dev, &dev_attr_idlecpus); 354 return -ENODEV; 355 } 356 result = device_create_file(&device->dev, &dev_attr_rrtime); 357 if (result) { 358 device_remove_file(&device->dev, &dev_attr_idlecpus); 359 device_remove_file(&device->dev, &dev_attr_idlepct); 360 return -ENODEV; 361 } 362 return 0; 363 } 364 365 static void acpi_pad_remove_sysfs(struct acpi_device *device) 366 { 367 device_remove_file(&device->dev, &dev_attr_idlecpus); 368 device_remove_file(&device->dev, &dev_attr_idlepct); 369 device_remove_file(&device->dev, &dev_attr_rrtime); 370 } 371 372 /* Query firmware how many CPUs should be idle */ 373 static int acpi_pad_pur(acpi_handle handle, int *num_cpus) 374 { 375 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL}; 376 union acpi_object *package; 377 int rev, num, ret = -EINVAL; 378 379 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer))) 380 return -EINVAL; 381 382 if (!buffer.length || !buffer.pointer) 383 return -EINVAL; 384 385 package = buffer.pointer; 386 if (package->type != ACPI_TYPE_PACKAGE || package->package.count != 2) 387 goto out; 388 rev = package->package.elements[0].integer.value; 389 num = package->package.elements[1].integer.value; 390 if (rev != 1 || num < 0) 391 goto out; 392 *num_cpus = num; 393 ret = 0; 394 out: 395 kfree(buffer.pointer); 396 return ret; 397 } 398 399 /* Notify firmware how many CPUs are idle */ 400 static void acpi_pad_ost(acpi_handle handle, int stat, 401 uint32_t idle_cpus) 402 { 403 union acpi_object params[3] = { 404 {.type = ACPI_TYPE_INTEGER,}, 405 {.type = ACPI_TYPE_INTEGER,}, 406 {.type = ACPI_TYPE_BUFFER,}, 407 }; 408 struct acpi_object_list arg_list = {3, params}; 409 410 params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY; 411 params[1].integer.value = stat; 412 params[2].buffer.length = 4; 413 params[2].buffer.pointer = (void *)&idle_cpus; 414 acpi_evaluate_object(handle, "_OST", &arg_list, NULL); 415 } 416 417 static void acpi_pad_handle_notify(acpi_handle handle) 418 { 419 int num_cpus; 420 uint32_t idle_cpus; 421 422 mutex_lock(&isolated_cpus_lock); 423 if (acpi_pad_pur(handle, &num_cpus)) { 424 mutex_unlock(&isolated_cpus_lock); 425 return; 426 } 427 acpi_pad_idle_cpus(num_cpus); 428 idle_cpus = acpi_pad_idle_cpus_num(); 429 acpi_pad_ost(handle, 0, idle_cpus); 430 mutex_unlock(&isolated_cpus_lock); 431 } 432 433 static void acpi_pad_notify(acpi_handle handle, u32 event, 434 void *data) 435 { 436 struct acpi_device *device = data; 437 438 switch (event) { 439 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: 440 acpi_pad_handle_notify(handle); 441 acpi_bus_generate_proc_event(device, event, 0); 442 acpi_bus_generate_netlink_event(device->pnp.device_class, 443 dev_name(&device->dev), event, 0); 444 break; 445 default: 446 printk(KERN_WARNING"Unsupported event [0x%x]\n", event); 447 break; 448 } 449 } 450 451 static int acpi_pad_add(struct acpi_device *device) 452 { 453 acpi_status status; 454 455 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); 456 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); 457 458 if (acpi_pad_add_sysfs(device)) 459 return -ENODEV; 460 461 status = acpi_install_notify_handler(device->handle, 462 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); 463 if (ACPI_FAILURE(status)) { 464 acpi_pad_remove_sysfs(device); 465 return -ENODEV; 466 } 467 468 return 0; 469 } 470 471 static int acpi_pad_remove(struct acpi_device *device, 472 int type) 473 { 474 mutex_lock(&isolated_cpus_lock); 475 acpi_pad_idle_cpus(0); 476 mutex_unlock(&isolated_cpus_lock); 477 478 acpi_remove_notify_handler(device->handle, 479 ACPI_DEVICE_NOTIFY, acpi_pad_notify); 480 acpi_pad_remove_sysfs(device); 481 return 0; 482 } 483 484 static const struct acpi_device_id pad_device_ids[] = { 485 {"ACPI000C", 0}, 486 {"", 0}, 487 }; 488 MODULE_DEVICE_TABLE(acpi, pad_device_ids); 489 490 static struct acpi_driver acpi_pad_driver = { 491 .name = "processor_aggregator", 492 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, 493 .ids = pad_device_ids, 494 .ops = { 495 .add = acpi_pad_add, 496 .remove = acpi_pad_remove, 497 }, 498 }; 499 500 static int __init acpi_pad_init(void) 501 { 502 power_saving_mwait_init(); 503 if (power_saving_mwait_eax == 0) 504 return -EINVAL; 505 506 return acpi_bus_register_driver(&acpi_pad_driver); 507 } 508 509 static void __exit acpi_pad_exit(void) 510 { 511 acpi_bus_unregister_driver(&acpi_pad_driver); 512 } 513 514 module_init(acpi_pad_init); 515 module_exit(acpi_pad_exit); 516 MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>"); 517 MODULE_DESCRIPTION("ACPI Processor Aggregator Driver"); 518 MODULE_LICENSE("GPL"); 519