GNU Linux-libre 4.4.289-gnu1
[releases.git] / 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                 free_cpumask_var(tmp);
112                 return;
113         }
114         for_each_cpu(cpu, tmp) {
115                 if (cpu_weight[cpu] < min_weight) {
116                         min_weight = cpu_weight[cpu];
117                         preferred_cpu = cpu;
118                 }
119         }
120
121         if (tsk_in_cpu[tsk_index] != -1)
122                 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
123         tsk_in_cpu[tsk_index] = preferred_cpu;
124         cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
125         cpu_weight[preferred_cpu]++;
126         mutex_unlock(&round_robin_lock);
127
128         set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
129
130         free_cpumask_var(tmp);
131 }
132
133 static void exit_round_robin(unsigned int tsk_index)
134 {
135         struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
136         cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
137         tsk_in_cpu[tsk_index] = -1;
138 }
139
140 static unsigned int idle_pct = 5; /* percentage */
141 static unsigned int round_robin_time = 1; /* second */
142 static int power_saving_thread(void *data)
143 {
144         struct sched_param param = {.sched_priority = 1};
145         int do_sleep;
146         unsigned int tsk_index = (unsigned long)data;
147         u64 last_jiffies = 0;
148
149         sched_setscheduler(current, SCHED_RR, &param);
150
151         while (!kthread_should_stop()) {
152                 unsigned long expire_time;
153
154                 /* round robin to cpus */
155                 expire_time = last_jiffies + round_robin_time * HZ;
156                 if (time_before(expire_time, jiffies)) {
157                         last_jiffies = jiffies;
158                         round_robin_cpu(tsk_index);
159                 }
160
161                 do_sleep = 0;
162
163                 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
164
165                 while (!need_resched()) {
166                         if (tsc_detected_unstable && !tsc_marked_unstable) {
167                                 /* TSC could halt in idle, so notify users */
168                                 mark_tsc_unstable("TSC halts in idle");
169                                 tsc_marked_unstable = 1;
170                         }
171                         local_irq_disable();
172                         tick_broadcast_enable();
173                         tick_broadcast_enter();
174                         stop_critical_timings();
175
176                         mwait_idle_with_hints(power_saving_mwait_eax, 1);
177
178                         start_critical_timings();
179                         tick_broadcast_exit();
180                         local_irq_enable();
181
182                         if (time_before(expire_time, jiffies)) {
183                                 do_sleep = 1;
184                                 break;
185                         }
186                 }
187
188                 /*
189                  * current sched_rt has threshold for rt task running time.
190                  * When a rt task uses 95% CPU time, the rt thread will be
191                  * scheduled out for 5% CPU time to not starve other tasks. But
192                  * the mechanism only works when all CPUs have RT task running,
193                  * as if one CPU hasn't RT task, RT task from other CPUs will
194                  * borrow CPU time from this CPU and cause RT task use > 95%
195                  * CPU time. To make 'avoid starvation' work, takes a nap here.
196                  */
197                 if (unlikely(do_sleep))
198                         schedule_timeout_killable(HZ * idle_pct / 100);
199
200                 /* If an external event has set the need_resched flag, then
201                  * we need to deal with it, or this loop will continue to
202                  * spin without calling __mwait().
203                  */
204                 if (unlikely(need_resched()))
205                         schedule();
206         }
207
208         exit_round_robin(tsk_index);
209         return 0;
210 }
211
212 static struct task_struct *ps_tsks[NR_CPUS];
213 static unsigned int ps_tsk_num;
214 static int create_power_saving_task(void)
215 {
216         int rc;
217
218         ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
219                 (void *)(unsigned long)ps_tsk_num,
220                 "acpi_pad/%d", ps_tsk_num);
221
222         if (IS_ERR(ps_tsks[ps_tsk_num])) {
223                 rc = PTR_ERR(ps_tsks[ps_tsk_num]);
224                 ps_tsks[ps_tsk_num] = NULL;
225         } else {
226                 rc = 0;
227                 ps_tsk_num++;
228         }
229
230         return rc;
231 }
232
233 static void destroy_power_saving_task(void)
234 {
235         if (ps_tsk_num > 0) {
236                 ps_tsk_num--;
237                 kthread_stop(ps_tsks[ps_tsk_num]);
238                 ps_tsks[ps_tsk_num] = NULL;
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 void 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 }
264
265 static uint32_t acpi_pad_idle_cpus_num(void)
266 {
267         return ps_tsk_num;
268 }
269
270 static ssize_t acpi_pad_rrtime_store(struct device *dev,
271         struct device_attribute *attr, const char *buf, size_t count)
272 {
273         unsigned long num;
274         if (kstrtoul(buf, 0, &num))
275                 return -EINVAL;
276         if (num < 1 || num >= 100)
277                 return -EINVAL;
278         mutex_lock(&isolated_cpus_lock);
279         round_robin_time = num;
280         mutex_unlock(&isolated_cpus_lock);
281         return count;
282 }
283
284 static ssize_t acpi_pad_rrtime_show(struct device *dev,
285         struct device_attribute *attr, char *buf)
286 {
287         return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time);
288 }
289 static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
290         acpi_pad_rrtime_show,
291         acpi_pad_rrtime_store);
292
293 static ssize_t acpi_pad_idlepct_store(struct device *dev,
294         struct device_attribute *attr, const char *buf, size_t count)
295 {
296         unsigned long num;
297         if (kstrtoul(buf, 0, &num))
298                 return -EINVAL;
299         if (num < 1 || num >= 100)
300                 return -EINVAL;
301         mutex_lock(&isolated_cpus_lock);
302         idle_pct = num;
303         mutex_unlock(&isolated_cpus_lock);
304         return count;
305 }
306
307 static ssize_t acpi_pad_idlepct_show(struct device *dev,
308         struct device_attribute *attr, char *buf)
309 {
310         return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct);
311 }
312 static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
313         acpi_pad_idlepct_show,
314         acpi_pad_idlepct_store);
315
316 static ssize_t acpi_pad_idlecpus_store(struct device *dev,
317         struct device_attribute *attr, const char *buf, size_t count)
318 {
319         unsigned long num;
320         if (kstrtoul(buf, 0, &num))
321                 return -EINVAL;
322         mutex_lock(&isolated_cpus_lock);
323         acpi_pad_idle_cpus(num);
324         mutex_unlock(&isolated_cpus_lock);
325         return count;
326 }
327
328 static ssize_t acpi_pad_idlecpus_show(struct device *dev,
329         struct device_attribute *attr, char *buf)
330 {
331         return cpumap_print_to_pagebuf(false, buf,
332                                        to_cpumask(pad_busy_cpus_bits));
333 }
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 /*
368  * Query firmware how many CPUs should be idle
369  * return -1 on failure
370  */
371 static int acpi_pad_pur(acpi_handle handle)
372 {
373         struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
374         union acpi_object *package;
375         int num = -1;
376
377         if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
378                 return num;
379
380         if (!buffer.length || !buffer.pointer)
381                 return num;
382
383         package = buffer.pointer;
384
385         if (package->type == ACPI_TYPE_PACKAGE &&
386                 package->package.count == 2 &&
387                 package->package.elements[0].integer.value == 1) /* rev 1 */
388
389                 num = package->package.elements[1].integer.value;
390
391         kfree(buffer.pointer);
392         return num;
393 }
394
395 static void acpi_pad_handle_notify(acpi_handle handle)
396 {
397         int num_cpus;
398         uint32_t idle_cpus;
399         struct acpi_buffer param = {
400                 .length = 4,
401                 .pointer = (void *)&idle_cpus,
402         };
403
404         mutex_lock(&isolated_cpus_lock);
405         num_cpus = acpi_pad_pur(handle);
406         if (num_cpus < 0) {
407                 mutex_unlock(&isolated_cpus_lock);
408                 return;
409         }
410         acpi_pad_idle_cpus(num_cpus);
411         idle_cpus = acpi_pad_idle_cpus_num();
412         acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, &param);
413         mutex_unlock(&isolated_cpus_lock);
414 }
415
416 static void acpi_pad_notify(acpi_handle handle, u32 event,
417         void *data)
418 {
419         struct acpi_device *device = data;
420
421         switch (event) {
422         case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
423                 acpi_pad_handle_notify(handle);
424                 acpi_bus_generate_netlink_event(device->pnp.device_class,
425                         dev_name(&device->dev), event, 0);
426                 break;
427         default:
428                 pr_warn("Unsupported event [0x%x]\n", event);
429                 break;
430         }
431 }
432
433 static int acpi_pad_add(struct acpi_device *device)
434 {
435         acpi_status status;
436
437         strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
438         strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
439
440         if (acpi_pad_add_sysfs(device))
441                 return -ENODEV;
442
443         status = acpi_install_notify_handler(device->handle,
444                 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
445         if (ACPI_FAILURE(status)) {
446                 acpi_pad_remove_sysfs(device);
447                 return -ENODEV;
448         }
449
450         return 0;
451 }
452
453 static int acpi_pad_remove(struct acpi_device *device)
454 {
455         mutex_lock(&isolated_cpus_lock);
456         acpi_pad_idle_cpus(0);
457         mutex_unlock(&isolated_cpus_lock);
458
459         acpi_remove_notify_handler(device->handle,
460                 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
461         acpi_pad_remove_sysfs(device);
462         return 0;
463 }
464
465 static const struct acpi_device_id pad_device_ids[] = {
466         {"ACPI000C", 0},
467         {"", 0},
468 };
469 MODULE_DEVICE_TABLE(acpi, pad_device_ids);
470
471 static struct acpi_driver acpi_pad_driver = {
472         .name = "processor_aggregator",
473         .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
474         .ids = pad_device_ids,
475         .ops = {
476                 .add = acpi_pad_add,
477                 .remove = acpi_pad_remove,
478         },
479 };
480
481 static int __init acpi_pad_init(void)
482 {
483         power_saving_mwait_init();
484         if (power_saving_mwait_eax == 0)
485                 return -EINVAL;
486
487         return acpi_bus_register_driver(&acpi_pad_driver);
488 }
489
490 static void __exit acpi_pad_exit(void)
491 {
492         acpi_bus_unregister_driver(&acpi_pad_driver);
493 }
494
495 module_init(acpi_pad_init);
496 module_exit(acpi_pad_exit);
497 MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
498 MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
499 MODULE_LICENSE("GPL");