Merge branch 'for-rmk/samsung6' of git://git.fluff.org/bjdooks/linux into devel-stable
[linux-2.6.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  * 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, &param);
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 *)&current_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");