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