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 <uapi/linux/sched/types.h>
  24 #include <linux/freezer.h>
  25 #include <linux/cpu.h>
  26 #include <linux/tick.h>
  27 #include <linux/slab.h>
  28 #include <linux/acpi.h>
  29 #include <asm/mwait.h>
  30 #include <xen/xen.h>
  31
  32 #define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
  33 #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
  34 #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
  35 static DEFINE_MUTEX(isolated_cpus_lock);
  36 static DEFINE_MUTEX(round_robin_lock);
  37
  38 static unsigned long power_saving_mwait_eax;
  39
  40 static unsigned char tsc_detected_unstable;
  41 static unsigned char tsc_marked_unstable;
  42
  43 static void power_saving_mwait_init(void)
  44 {
  45         unsigned int eax, ebx, ecx, edx;
  46         unsigned int highest_cstate = 0;
  47         unsigned int highest_subcstate = 0;
  48         int i;
  49
  50         if (!boot_cpu_has(X86_FEATURE_MWAIT))
  51                 return;
  52         if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
  53                 return;
  54
  55         cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
  56
  57         if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
  58             !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
  59                 return;
  60
  61         edx >>= MWAIT_SUBSTATE_SIZE;
  62         for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
  63                 if (edx & MWAIT_SUBSTATE_MASK) {
  64                         highest_cstate = i;
  65                         highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
  66                 }
  67         }
  68         power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
  69                 (highest_subcstate - 1);
  70
  71 #if defined(CONFIG_X86)
  72         switch (boot_cpu_data.x86_vendor) {
  73         case X86_VENDOR_HYGON:
  74         case X86_VENDOR_AMD:
  75         case X86_VENDOR_INTEL:
  76                 /*
  77                  * AMD Fam10h TSC will tick in all
  78                  * C/P/S0/S1 states when this bit is set.
  79                  */
  80                 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
  81                         tsc_detected_unstable = 1;
  82                 break;
  83         default:
  84                 /* TSC could halt in idle */
  85                 tsc_detected_unstable = 1;
  86         }
  87 #endif
  88 }
  89
  90 static unsigned long cpu_weight[NR_CPUS];
  91 static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
  92 static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
  93 static void round_robin_cpu(unsigned int tsk_index)
  94 {
  95         struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
  96         cpumask_var_t tmp;
  97         int cpu;
  98         unsigned long min_weight = -1;
  99         unsigned long uninitialized_var(preferred_cpu);
 100
 101         if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
 102                 return;
 103
 104         mutex_lock(&round_robin_lock);
 105         cpumask_clear(tmp);
 106         for_each_cpu(cpu, pad_busy_cpus)
 107                 cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu));
 108         cpumask_andnot(tmp, cpu_online_mask, tmp);
 109         /* avoid HT sibilings if possible */
 110         if (cpumask_empty(tmp))
 111                 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
 112         if (cpumask_empty(tmp)) {
 113                 mutex_unlock(&round_robin_lock);
 114                 free_cpumask_var(tmp);
 115                 return;
 116         }
 117         for_each_cpu(cpu, tmp) {
 118                 if (cpu_weight[cpu] < min_weight) {
 119                         min_weight = cpu_weight[cpu];
 120                         preferred_cpu = cpu;
 121                 }
 122         }
 123
 124         if (tsk_in_cpu[tsk_index] != -1)
 125                 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
 126         tsk_in_cpu[tsk_index] = preferred_cpu;
 127         cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
 128         cpu_weight[preferred_cpu]++;
 129         mutex_unlock(&round_robin_lock);
 130
 131         set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
 132
 133         free_cpumask_var(tmp);
 134 }
 135
 136 static void exit_round_robin(unsigned int tsk_index)
 137 {
 138         struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
 139         cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
 140         tsk_in_cpu[tsk_index] = -1;
 141 }
 142
 143 static unsigned int idle_pct = 5; /* percentage */
 144 static unsigned int round_robin_time = 1; /* second */
 145 static int power_saving_thread(void *data)
 146 {
 147         struct sched_param param = {.sched_priority = 1};
 148         int do_sleep;
 149         unsigned int tsk_index = (unsigned long)data;
 150         u64 last_jiffies = 0;
 151
 152         sched_setscheduler(current, SCHED_RR, &param);
 153
 154         while (!kthread_should_stop()) {
 155                 unsigned long expire_time;
 156
 157                 /* round robin to cpus */
 158                 expire_time = last_jiffies + round_robin_time * HZ;
 159                 if (time_before(expire_time, jiffies)) {
 160                         last_jiffies = jiffies;
 161                         round_robin_cpu(tsk_index);
 162                 }
 163
 164                 do_sleep = 0;
 165
 166                 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
 167
 168                 while (!need_resched()) {
 169                         if (tsc_detected_unstable && !tsc_marked_unstable) {
 170                                 /* TSC could halt in idle, so notify users */
 171                                 mark_tsc_unstable("TSC halts in idle");
 172                                 tsc_marked_unstable = 1;
 173                         }
 174                         local_irq_disable();
 175                         tick_broadcast_enable();
 176                         tick_broadcast_enter();
 177                         stop_critical_timings();
 178
 179                         mwait_idle_with_hints(power_saving_mwait_eax, 1);
 180
 181                         start_critical_timings();
 182                         tick_broadcast_exit();
 183                         local_irq_enable();
 184
 185                         if (time_before(expire_time, jiffies)) {
 186                                 do_sleep = 1;
 187                                 break;
 188                         }
 189                 }
 190
 191                 /*
 192                  * current sched_rt has threshold for rt task running time.
 193                  * When a rt task uses 95% CPU time, the rt thread will be
 194                  * scheduled out for 5% CPU time to not starve other tasks. But
 195                  * the mechanism only works when all CPUs have RT task running,
 196                  * as if one CPU hasn't RT task, RT task from other CPUs will
 197                  * borrow CPU time from this CPU and cause RT task use > 95%
 198                  * CPU time. To make 'avoid starvation' work, takes a nap here.
 199                  */
 200                 if (unlikely(do_sleep))
 201                         schedule_timeout_killable(HZ * idle_pct / 100);
 202
 203                 /* If an external event has set the need_resched flag, then
 204                  * we need to deal with it, or this loop will continue to
 205                  * spin without calling __mwait().
 206                  */
 207                 if (unlikely(need_resched()))
 208                         schedule();
 209         }
 210
 211         exit_round_robin(tsk_index);
 212         return 0;
 213 }
 214
 215 static struct task_struct *ps_tsks[NR_CPUS];
 216 static unsigned int ps_tsk_num;
 217 static int create_power_saving_task(void)
 218 {
 219         int rc;
 220
 221         ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
 222                 (void *)(unsigned long)ps_tsk_num,
 223                 "acpi_pad/%d", ps_tsk_num);
 224
 225         if (IS_ERR(ps_tsks[ps_tsk_num])) {
 226                 rc = PTR_ERR(ps_tsks[ps_tsk_num]);
 227                 ps_tsks[ps_tsk_num] = NULL;
 228         } else {
 229                 rc = 0;
 230                 ps_tsk_num++;
 231         }
 232
 233         return rc;
 234 }
 235
 236 static void destroy_power_saving_task(void)
 237 {
 238         if (ps_tsk_num > 0) {
 239                 ps_tsk_num--;
 240                 kthread_stop(ps_tsks[ps_tsk_num]);
 241                 ps_tsks[ps_tsk_num] = NULL;
 242         }
 243 }
 244
 245 static void set_power_saving_task_num(unsigned int num)
 246 {
 247         if (num > ps_tsk_num) {
 248                 while (ps_tsk_num < num) {
 249                         if (create_power_saving_task())
 250                                 return;
 251                 }
 252         } else if (num < ps_tsk_num) {
 253                 while (ps_tsk_num > num)
 254                         destroy_power_saving_task();
 255         }
 256 }
 257
 258 static void acpi_pad_idle_cpus(unsigned int num_cpus)
 259 {
 260         get_online_cpus();
 261
 262         num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
 263         set_power_saving_task_num(num_cpus);
 264
 265         put_online_cpus();
 266 }
 267
 268 static uint32_t acpi_pad_idle_cpus_num(void)
 269 {
 270         return ps_tsk_num;
 271 }
 272
 273 static ssize_t acpi_pad_rrtime_store(struct device *dev,
 274         struct device_attribute *attr, const char *buf, size_t count)
 275 {
 276         unsigned long num;
 277         if (kstrtoul(buf, 0, &num))
 278                 return -EINVAL;
 279         if (num < 1 || num >= 100)
 280                 return -EINVAL;
 281         mutex_lock(&isolated_cpus_lock);
 282         round_robin_time = num;
 283         mutex_unlock(&isolated_cpus_lock);
 284         return count;
 285 }
 286
 287 static ssize_t acpi_pad_rrtime_show(struct device *dev,
 288         struct device_attribute *attr, char *buf)
 289 {
 290         return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time);
 291 }
 292 static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
 293         acpi_pad_rrtime_show,
 294         acpi_pad_rrtime_store);
 295
 296 static ssize_t acpi_pad_idlepct_store(struct device *dev,
 297         struct device_attribute *attr, const char *buf, size_t count)
 298 {
 299         unsigned long num;
 300         if (kstrtoul(buf, 0, &num))
 301                 return -EINVAL;
 302         if (num < 1 || num >= 100)
 303                 return -EINVAL;
 304         mutex_lock(&isolated_cpus_lock);
 305         idle_pct = num;
 306         mutex_unlock(&isolated_cpus_lock);
 307         return count;
 308 }
 309
 310 static ssize_t acpi_pad_idlepct_show(struct device *dev,
 311         struct device_attribute *attr, char *buf)
 312 {
 313         return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct);
 314 }
 315 static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
 316         acpi_pad_idlepct_show,
 317         acpi_pad_idlepct_store);
 318
 319 static ssize_t acpi_pad_idlecpus_store(struct device *dev,
 320         struct device_attribute *attr, const char *buf, size_t count)
 321 {
 322         unsigned long num;
 323         if (kstrtoul(buf, 0, &num))
 324                 return -EINVAL;
 325         mutex_lock(&isolated_cpus_lock);
 326         acpi_pad_idle_cpus(num);
 327         mutex_unlock(&isolated_cpus_lock);
 328         return count;
 329 }
 330
 331 static ssize_t acpi_pad_idlecpus_show(struct device *dev,
 332         struct device_attribute *attr, char *buf)
 333 {
 334         return cpumap_print_to_pagebuf(false, buf,
 335                                        to_cpumask(pad_busy_cpus_bits));
 336 }
 337
 338 static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
 339         acpi_pad_idlecpus_show,
 340         acpi_pad_idlecpus_store);
 341
 342 static int acpi_pad_add_sysfs(struct acpi_device *device)
 343 {
 344         int result;
 345
 346         result = device_create_file(&device->dev, &dev_attr_idlecpus);
 347         if (result)
 348                 return -ENODEV;
 349         result = device_create_file(&device->dev, &dev_attr_idlepct);
 350         if (result) {
 351                 device_remove_file(&device->dev, &dev_attr_idlecpus);
 352                 return -ENODEV;
 353         }
 354         result = device_create_file(&device->dev, &dev_attr_rrtime);
 355         if (result) {
 356                 device_remove_file(&device->dev, &dev_attr_idlecpus);
 357                 device_remove_file(&device->dev, &dev_attr_idlepct);
 358                 return -ENODEV;
 359         }
 360         return 0;
 361 }
 362
 363 static void acpi_pad_remove_sysfs(struct acpi_device *device)
 364 {
 365         device_remove_file(&device->dev, &dev_attr_idlecpus);
 366         device_remove_file(&device->dev, &dev_attr_idlepct);
 367         device_remove_file(&device->dev, &dev_attr_rrtime);
 368 }
 369
 370 /*
 371  * Query firmware how many CPUs should be idle
 372  * return -1 on failure
 373  */
 374 static int acpi_pad_pur(acpi_handle handle)
 375 {
 376         struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
 377         union acpi_object *package;
 378         int num = -1;
 379
 380         if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
 381                 return num;
 382
 383         if (!buffer.length || !buffer.pointer)
 384                 return num;
 385
 386         package = buffer.pointer;
 387
 388         if (package->type == ACPI_TYPE_PACKAGE &&
 389                 package->package.count == 2 &&
 390                 package->package.elements[0].integer.value == 1) /* rev 1 */
 391
 392                 num = package->package.elements[1].integer.value;
 393
 394         kfree(buffer.pointer);
 395         return num;
 396 }
 397
 398 static void acpi_pad_handle_notify(acpi_handle handle)
 399 {
 400         int num_cpus;
 401         uint32_t idle_cpus;
 402         struct acpi_buffer param = {
 403                 .length = 4,
 404                 .pointer = (void *)&idle_cpus,
 405         };
 406
 407         mutex_lock(&isolated_cpus_lock);
 408         num_cpus = acpi_pad_pur(handle);
 409         if (num_cpus < 0) {
 410                 mutex_unlock(&isolated_cpus_lock);
 411                 return;
 412         }
 413         acpi_pad_idle_cpus(num_cpus);
 414         idle_cpus = acpi_pad_idle_cpus_num();
 415         acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, &param);
 416         mutex_unlock(&isolated_cpus_lock);
 417 }
 418
 419 static void acpi_pad_notify(acpi_handle handle, u32 event,
 420         void *data)
 421 {
 422         struct acpi_device *device = data;
 423
 424         switch (event) {
 425         case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
 426                 acpi_pad_handle_notify(handle);
 427                 acpi_bus_generate_netlink_event(device->pnp.device_class,
 428                         dev_name(&device->dev), event, 0);
 429                 break;
 430         default:
 431                 pr_warn("Unsupported event [0x%x]\n", event);
 432                 break;
 433         }
 434 }
 435
 436 static int acpi_pad_add(struct acpi_device *device)
 437 {
 438         acpi_status status;
 439
 440         strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
 441         strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
 442
 443         if (acpi_pad_add_sysfs(device))
 444                 return -ENODEV;
 445
 446         status = acpi_install_notify_handler(device->handle,
 447                 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
 448         if (ACPI_FAILURE(status)) {
 449                 acpi_pad_remove_sysfs(device);
 450                 return -ENODEV;
 451         }
 452
 453         return 0;
 454 }
 455
 456 static int acpi_pad_remove(struct acpi_device *device)
 457 {
 458         mutex_lock(&isolated_cpus_lock);
 459         acpi_pad_idle_cpus(0);
 460         mutex_unlock(&isolated_cpus_lock);
 461
 462         acpi_remove_notify_handler(device->handle,
 463                 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
 464         acpi_pad_remove_sysfs(device);
 465         return 0;
 466 }
 467
 468 static const struct acpi_device_id pad_device_ids[] = {
 469         {"ACPI000C", 0},
 470         {"", 0},
 471 };
 472 MODULE_DEVICE_TABLE(acpi, pad_device_ids);
 473
 474 static struct acpi_driver acpi_pad_driver = {
 475         .name = "processor_aggregator",
 476         .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
 477         .ids = pad_device_ids,
 478         .ops = {
 479                 .add = acpi_pad_add,
 480                 .remove = acpi_pad_remove,
 481         },
 482 };
 483
 484 static int __init acpi_pad_init(void)
 485 {
 486         /* Xen ACPI PAD is used when running as Xen Dom0. */
 487         if (xen_initial_domain())
 488                 return -ENODEV;
 489
 490         power_saving_mwait_init();
 491         if (power_saving_mwait_eax == 0)
 492                 return -EINVAL;
 493
 494         return acpi_bus_register_driver(&acpi_pad_driver);
 495 }
 496
 497 static void __exit acpi_pad_exit(void)
 498 {
 499         acpi_bus_unregister_driver(&acpi_pad_driver);
 500 }
 501
 502 module_init(acpi_pad_init);
 503 module_exit(acpi_pad_exit);
 504 MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
 505 MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
 506 MODULE_LICENSE("GPL");