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