drivers/acpi/acpi_pad.c

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