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[pohmelfs.git] / drivers / acpi / acpi_pad.c
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1 /*
2 * acpi_pad.c ACPI Processor Aggregator Driver
4 * Copyright (c) 2009, Intel Corporation.
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.
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.
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.
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 #include <asm/mwait.h>
35 #define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
36 #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
37 #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
38 static DEFINE_MUTEX(isolated_cpus_lock);
40 static unsigned long power_saving_mwait_eax;
42 static unsigned char tsc_detected_unstable;
43 static unsigned char tsc_marked_unstable;
44 static unsigned char lapic_detected_unstable;
45 static unsigned char lapic_marked_unstable;
47 static void power_saving_mwait_init(void)
49 unsigned int eax, ebx, ecx, edx;
50 unsigned int highest_cstate = 0;
51 unsigned int highest_subcstate = 0;
52 int i;
54 if (!boot_cpu_has(X86_FEATURE_MWAIT))
55 return;
56 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
57 return;
59 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
61 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
62 !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
63 return;
65 edx >>= MWAIT_SUBSTATE_SIZE;
66 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
67 if (edx & MWAIT_SUBSTATE_MASK) {
68 highest_cstate = i;
69 highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
72 power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
73 (highest_subcstate - 1);
75 #if defined(CONFIG_X86)
76 switch (boot_cpu_data.x86_vendor) {
77 case X86_VENDOR_AMD:
78 case X86_VENDOR_INTEL:
80 * AMD Fam10h TSC will tick in all
81 * C/P/S0/S1 states when this bit is set.
83 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
84 tsc_detected_unstable = 1;
85 if (!boot_cpu_has(X86_FEATURE_ARAT))
86 lapic_detected_unstable = 1;
87 break;
88 default:
89 /* TSC & LAPIC could halt in idle */
90 tsc_detected_unstable = 1;
91 lapic_detected_unstable = 1;
93 #endif
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)
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);
107 if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
108 return;
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;
122 for_each_cpu(cpu, tmp) {
123 if (cpu_weight[cpu] < min_weight) {
124 min_weight = cpu_weight[cpu];
125 preferred_cpu = cpu;
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);
136 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
139 static void exit_round_robin(unsigned int tsk_index)
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;
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)
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;
155 sched_setscheduler(current, SCHED_RR, &param);
157 while (!kthread_should_stop()) {
158 int cpu;
159 u64 expire_time;
161 try_to_freeze();
163 /* round robin to cpus */
164 if (last_jiffies + round_robin_time * HZ < jiffies) {
165 last_jiffies = jiffies;
166 round_robin_cpu(tsk_index);
169 do_sleep = 0;
171 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
173 while (!need_resched()) {
174 if (tsc_detected_unstable && !tsc_marked_unstable) {
175 /* TSC could halt in idle, so notify users */
176 mark_tsc_unstable("TSC halts in idle");
177 tsc_marked_unstable = 1;
179 if (lapic_detected_unstable && !lapic_marked_unstable) {
180 int i;
181 /* LAPIC could halt in idle, so notify users */
182 for_each_online_cpu(i)
183 clockevents_notify(
184 CLOCK_EVT_NOTIFY_BROADCAST_ON,
185 &i);
186 lapic_marked_unstable = 1;
188 local_irq_disable();
189 cpu = smp_processor_id();
190 if (lapic_marked_unstable)
191 clockevents_notify(
192 CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
193 stop_critical_timings();
195 __monitor((void *)&current_thread_info()->flags, 0, 0);
196 smp_mb();
197 if (!need_resched())
198 __mwait(power_saving_mwait_eax, 1);
200 start_critical_timings();
201 if (lapic_marked_unstable)
202 clockevents_notify(
203 CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
204 local_irq_enable();
206 if (jiffies > expire_time) {
207 do_sleep = 1;
208 break;
213 * current sched_rt has threshold for rt task running time.
214 * When a rt task uses 95% CPU time, the rt thread will be
215 * scheduled out for 5% CPU time to not starve other tasks. But
216 * the mechanism only works when all CPUs have RT task running,
217 * as if one CPU hasn't RT task, RT task from other CPUs will
218 * borrow CPU time from this CPU and cause RT task use > 95%
219 * CPU time. To make 'avoid starvation' work, takes a nap here.
221 if (do_sleep)
222 schedule_timeout_killable(HZ * idle_pct / 100);
225 exit_round_robin(tsk_index);
226 return 0;
229 static struct task_struct *ps_tsks[NR_CPUS];
230 static unsigned int ps_tsk_num;
231 static int create_power_saving_task(void)
233 int rc = -ENOMEM;
235 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
236 (void *)(unsigned long)ps_tsk_num,
237 "power_saving/%d", ps_tsk_num);
238 rc = IS_ERR(ps_tsks[ps_tsk_num]) ? PTR_ERR(ps_tsks[ps_tsk_num]) : 0;
239 if (!rc)
240 ps_tsk_num++;
241 else
242 ps_tsks[ps_tsk_num] = NULL;
244 return rc;
247 static void destroy_power_saving_task(void)
249 if (ps_tsk_num > 0) {
250 ps_tsk_num--;
251 kthread_stop(ps_tsks[ps_tsk_num]);
252 ps_tsks[ps_tsk_num] = NULL;
256 static void set_power_saving_task_num(unsigned int num)
258 if (num > ps_tsk_num) {
259 while (ps_tsk_num < num) {
260 if (create_power_saving_task())
261 return;
263 } else if (num < ps_tsk_num) {
264 while (ps_tsk_num > num)
265 destroy_power_saving_task();
269 static void acpi_pad_idle_cpus(unsigned int num_cpus)
271 get_online_cpus();
273 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
274 set_power_saving_task_num(num_cpus);
276 put_online_cpus();
279 static uint32_t acpi_pad_idle_cpus_num(void)
281 return ps_tsk_num;
284 static ssize_t acpi_pad_rrtime_store(struct device *dev,
285 struct device_attribute *attr, const char *buf, size_t count)
287 unsigned long num;
288 if (strict_strtoul(buf, 0, &num))
289 return -EINVAL;
290 if (num < 1 || num >= 100)
291 return -EINVAL;
292 mutex_lock(&isolated_cpus_lock);
293 round_robin_time = num;
294 mutex_unlock(&isolated_cpus_lock);
295 return count;
298 static ssize_t acpi_pad_rrtime_show(struct device *dev,
299 struct device_attribute *attr, char *buf)
301 return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time);
303 static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
304 acpi_pad_rrtime_show,
305 acpi_pad_rrtime_store);
307 static ssize_t acpi_pad_idlepct_store(struct device *dev,
308 struct device_attribute *attr, const char *buf, size_t count)
310 unsigned long num;
311 if (strict_strtoul(buf, 0, &num))
312 return -EINVAL;
313 if (num < 1 || num >= 100)
314 return -EINVAL;
315 mutex_lock(&isolated_cpus_lock);
316 idle_pct = num;
317 mutex_unlock(&isolated_cpus_lock);
318 return count;
321 static ssize_t acpi_pad_idlepct_show(struct device *dev,
322 struct device_attribute *attr, char *buf)
324 return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct);
326 static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
327 acpi_pad_idlepct_show,
328 acpi_pad_idlepct_store);
330 static ssize_t acpi_pad_idlecpus_store(struct device *dev,
331 struct device_attribute *attr, const char *buf, size_t count)
333 unsigned long num;
334 if (strict_strtoul(buf, 0, &num))
335 return -EINVAL;
336 mutex_lock(&isolated_cpus_lock);
337 acpi_pad_idle_cpus(num);
338 mutex_unlock(&isolated_cpus_lock);
339 return count;
342 static ssize_t acpi_pad_idlecpus_show(struct device *dev,
343 struct device_attribute *attr, char *buf)
345 int n = 0;
346 n = cpumask_scnprintf(buf, PAGE_SIZE-2, to_cpumask(pad_busy_cpus_bits));
347 buf[n++] = '\n';
348 buf[n] = '\0';
349 return n;
351 static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
352 acpi_pad_idlecpus_show,
353 acpi_pad_idlecpus_store);
355 static int acpi_pad_add_sysfs(struct acpi_device *device)
357 int result;
359 result = device_create_file(&device->dev, &dev_attr_idlecpus);
360 if (result)
361 return -ENODEV;
362 result = device_create_file(&device->dev, &dev_attr_idlepct);
363 if (result) {
364 device_remove_file(&device->dev, &dev_attr_idlecpus);
365 return -ENODEV;
367 result = device_create_file(&device->dev, &dev_attr_rrtime);
368 if (result) {
369 device_remove_file(&device->dev, &dev_attr_idlecpus);
370 device_remove_file(&device->dev, &dev_attr_idlepct);
371 return -ENODEV;
373 return 0;
376 static void acpi_pad_remove_sysfs(struct acpi_device *device)
378 device_remove_file(&device->dev, &dev_attr_idlecpus);
379 device_remove_file(&device->dev, &dev_attr_idlepct);
380 device_remove_file(&device->dev, &dev_attr_rrtime);
384 * Query firmware how many CPUs should be idle
385 * return -1 on failure
387 static int acpi_pad_pur(acpi_handle handle)
389 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
390 union acpi_object *package;
391 int num = -1;
393 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
394 return num;
396 if (!buffer.length || !buffer.pointer)
397 return num;
399 package = buffer.pointer;
401 if (package->type == ACPI_TYPE_PACKAGE &&
402 package->package.count == 2 &&
403 package->package.elements[0].integer.value == 1) /* rev 1 */
405 num = package->package.elements[1].integer.value;
407 kfree(buffer.pointer);
408 return num;
411 /* Notify firmware how many CPUs are idle */
412 static void acpi_pad_ost(acpi_handle handle, int stat,
413 uint32_t idle_cpus)
415 union acpi_object params[3] = {
416 {.type = ACPI_TYPE_INTEGER,},
417 {.type = ACPI_TYPE_INTEGER,},
418 {.type = ACPI_TYPE_BUFFER,},
420 struct acpi_object_list arg_list = {3, params};
422 params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY;
423 params[1].integer.value = stat;
424 params[2].buffer.length = 4;
425 params[2].buffer.pointer = (void *)&idle_cpus;
426 acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
429 static void acpi_pad_handle_notify(acpi_handle handle)
431 int num_cpus;
432 uint32_t idle_cpus;
434 mutex_lock(&isolated_cpus_lock);
435 num_cpus = acpi_pad_pur(handle);
436 if (num_cpus < 0) {
437 mutex_unlock(&isolated_cpus_lock);
438 return;
440 acpi_pad_idle_cpus(num_cpus);
441 idle_cpus = acpi_pad_idle_cpus_num();
442 acpi_pad_ost(handle, 0, idle_cpus);
443 mutex_unlock(&isolated_cpus_lock);
446 static void acpi_pad_notify(acpi_handle handle, u32 event,
447 void *data)
449 struct acpi_device *device = data;
451 switch (event) {
452 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
453 acpi_pad_handle_notify(handle);
454 acpi_bus_generate_proc_event(device, event, 0);
455 acpi_bus_generate_netlink_event(device->pnp.device_class,
456 dev_name(&device->dev), event, 0);
457 break;
458 default:
459 printk(KERN_WARNING "Unsupported event [0x%x]\n", event);
460 break;
464 static int acpi_pad_add(struct acpi_device *device)
466 acpi_status status;
468 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
469 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
471 if (acpi_pad_add_sysfs(device))
472 return -ENODEV;
474 status = acpi_install_notify_handler(device->handle,
475 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
476 if (ACPI_FAILURE(status)) {
477 acpi_pad_remove_sysfs(device);
478 return -ENODEV;
481 return 0;
484 static int acpi_pad_remove(struct acpi_device *device,
485 int type)
487 mutex_lock(&isolated_cpus_lock);
488 acpi_pad_idle_cpus(0);
489 mutex_unlock(&isolated_cpus_lock);
491 acpi_remove_notify_handler(device->handle,
492 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
493 acpi_pad_remove_sysfs(device);
494 return 0;
497 static const struct acpi_device_id pad_device_ids[] = {
498 {"ACPI000C", 0},
499 {"", 0},
501 MODULE_DEVICE_TABLE(acpi, pad_device_ids);
503 static struct acpi_driver acpi_pad_driver = {
504 .name = "processor_aggregator",
505 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
506 .ids = pad_device_ids,
507 .ops = {
508 .add = acpi_pad_add,
509 .remove = acpi_pad_remove,
513 static int __init acpi_pad_init(void)
515 power_saving_mwait_init();
516 if (power_saving_mwait_eax == 0)
517 return -EINVAL;
519 return acpi_bus_register_driver(&acpi_pad_driver);
522 static void __exit acpi_pad_exit(void)
524 acpi_bus_unregister_driver(&acpi_pad_driver);
527 module_init(acpi_pad_init);
528 module_exit(acpi_pad_exit);
529 MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
530 MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
531 MODULE_LICENSE("GPL");