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8e0af514 SL |
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 | * | |
8e0af514 SL |
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> | |
979081e7 | 25 | #include <linux/tick.h> |
5a0e3ad6 | 26 | #include <linux/slab.h> |
8b48463f | 27 | #include <linux/acpi.h> |
bc83cccc | 28 | #include <asm/mwait.h> |
8e0af514 | 29 | |
a40770a9 | 30 | #define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad" |
8e0af514 SL |
31 | #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator" |
32 | #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80 | |
33 | static DEFINE_MUTEX(isolated_cpus_lock); | |
5f160126 | 34 | static DEFINE_MUTEX(round_robin_lock); |
8e0af514 | 35 | |
8e0af514 | 36 | static unsigned long power_saving_mwait_eax; |
0dc698b9 VP |
37 | |
38 | static unsigned char tsc_detected_unstable; | |
39 | static unsigned char tsc_marked_unstable; | |
40 | ||
8e0af514 SL |
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 | ||
592913ec | 69 | #if defined(CONFIG_X86) |
8e0af514 SL |
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 | */ | |
8aa4b14e CG |
77 | if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) |
78 | tsc_detected_unstable = 1; | |
8aa4b14e | 79 | break; |
8e0af514 | 80 | default: |
3ff70551 | 81 | /* TSC could halt in idle */ |
0dc698b9 | 82 | tsc_detected_unstable = 1; |
8e0af514 SL |
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; | |
f67538f8 AM |
95 | unsigned long min_weight = -1; |
96 | unsigned long uninitialized_var(preferred_cpu); | |
8e0af514 SL |
97 | |
98 | if (!alloc_cpumask_var(&tmp, GFP_KERNEL)) | |
99 | return; | |
100 | ||
5f160126 | 101 | mutex_lock(&round_robin_lock); |
8e0af514 SL |
102 | cpumask_clear(tmp); |
103 | for_each_cpu(cpu, pad_busy_cpus) | |
06931e62 | 104 | cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu)); |
8e0af514 SL |
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)) { | |
5f160126 | 110 | mutex_unlock(&round_robin_lock); |
8e0af514 SL |
111 | return; |
112 | } | |
113 | for_each_cpu(cpu, tmp) { | |
114 | if (cpu_weight[cpu] < min_weight) { | |
115 | min_weight = cpu_weight[cpu]; | |
116 | preferred_cpu = cpu; | |
117 | } | |
118 | } | |
119 | ||
120 | if (tsk_in_cpu[tsk_index] != -1) | |
121 | cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); | |
122 | tsk_in_cpu[tsk_index] = preferred_cpu; | |
123 | cpumask_set_cpu(preferred_cpu, pad_busy_cpus); | |
124 | cpu_weight[preferred_cpu]++; | |
5f160126 | 125 | mutex_unlock(&round_robin_lock); |
8e0af514 SL |
126 | |
127 | set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu)); | |
128 | } | |
129 | ||
130 | static void exit_round_robin(unsigned int tsk_index) | |
131 | { | |
132 | struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); | |
133 | cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); | |
134 | tsk_in_cpu[tsk_index] = -1; | |
135 | } | |
136 | ||
137 | static unsigned int idle_pct = 5; /* percentage */ | |
fa7584e1 | 138 | static unsigned int round_robin_time = 1; /* second */ |
8e0af514 SL |
139 | static int power_saving_thread(void *data) |
140 | { | |
141 | struct sched_param param = {.sched_priority = 1}; | |
142 | int do_sleep; | |
143 | unsigned int tsk_index = (unsigned long)data; | |
144 | u64 last_jiffies = 0; | |
145 | ||
146 | sched_setscheduler(current, SCHED_RR, ¶m); | |
147 | ||
148 | while (!kthread_should_stop()) { | |
4ff248f3 | 149 | unsigned long expire_time; |
8e0af514 | 150 | |
8e0af514 | 151 | /* round robin to cpus */ |
4ff248f3 MS |
152 | expire_time = last_jiffies + round_robin_time * HZ; |
153 | if (time_before(expire_time, jiffies)) { | |
8e0af514 SL |
154 | last_jiffies = jiffies; |
155 | round_robin_cpu(tsk_index); | |
156 | } | |
157 | ||
158 | do_sleep = 0; | |
159 | ||
8e0af514 SL |
160 | expire_time = jiffies + HZ * (100 - idle_pct) / 100; |
161 | ||
162 | while (!need_resched()) { | |
0dc698b9 VP |
163 | if (tsc_detected_unstable && !tsc_marked_unstable) { |
164 | /* TSC could halt in idle, so notify users */ | |
165 | mark_tsc_unstable("TSC halts in idle"); | |
166 | tsc_marked_unstable = 1; | |
167 | } | |
8e0af514 | 168 | local_irq_disable(); |
979081e7 | 169 | tick_broadcast_enable(); |
c7952135 | 170 | tick_broadcast_enter(); |
8e0af514 SL |
171 | stop_critical_timings(); |
172 | ||
16824255 | 173 | mwait_idle_with_hints(power_saving_mwait_eax, 1); |
8e0af514 SL |
174 | |
175 | start_critical_timings(); | |
c7952135 | 176 | tick_broadcast_exit(); |
8e0af514 SL |
177 | local_irq_enable(); |
178 | ||
4ff248f3 | 179 | if (time_before(expire_time, jiffies)) { |
8e0af514 SL |
180 | do_sleep = 1; |
181 | break; | |
182 | } | |
183 | } | |
184 | ||
8e0af514 SL |
185 | /* |
186 | * current sched_rt has threshold for rt task running time. | |
187 | * When a rt task uses 95% CPU time, the rt thread will be | |
188 | * scheduled out for 5% CPU time to not starve other tasks. But | |
189 | * the mechanism only works when all CPUs have RT task running, | |
190 | * as if one CPU hasn't RT task, RT task from other CPUs will | |
191 | * borrow CPU time from this CPU and cause RT task use > 95% | |
3b8cb427 | 192 | * CPU time. To make 'avoid starvation' work, takes a nap here. |
8e0af514 | 193 | */ |
5b59c69e | 194 | if (unlikely(do_sleep)) |
8e0af514 | 195 | schedule_timeout_killable(HZ * idle_pct / 100); |
5b59c69e TC |
196 | |
197 | /* If an external event has set the need_resched flag, then | |
198 | * we need to deal with it, or this loop will continue to | |
199 | * spin without calling __mwait(). | |
200 | */ | |
201 | if (unlikely(need_resched())) | |
202 | schedule(); | |
8e0af514 SL |
203 | } |
204 | ||
205 | exit_round_robin(tsk_index); | |
206 | return 0; | |
207 | } | |
208 | ||
209 | static struct task_struct *ps_tsks[NR_CPUS]; | |
210 | static unsigned int ps_tsk_num; | |
211 | static int create_power_saving_task(void) | |
212 | { | |
5d7e4386 | 213 | int rc; |
3b8cb427 | 214 | |
8e0af514 SL |
215 | ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread, |
216 | (void *)(unsigned long)ps_tsk_num, | |
150ed86f | 217 | "acpi_pad/%d", ps_tsk_num); |
5d7e4386 RR |
218 | |
219 | if (IS_ERR(ps_tsks[ps_tsk_num])) { | |
220 | rc = PTR_ERR(ps_tsks[ps_tsk_num]); | |
3b8cb427 | 221 | ps_tsks[ps_tsk_num] = NULL; |
5d7e4386 RR |
222 | } else { |
223 | rc = 0; | |
224 | ps_tsk_num++; | |
225 | } | |
3b8cb427 CG |
226 | |
227 | return rc; | |
8e0af514 SL |
228 | } |
229 | ||
230 | static void destroy_power_saving_task(void) | |
231 | { | |
232 | if (ps_tsk_num > 0) { | |
233 | ps_tsk_num--; | |
234 | kthread_stop(ps_tsks[ps_tsk_num]); | |
3b8cb427 | 235 | ps_tsks[ps_tsk_num] = NULL; |
8e0af514 SL |
236 | } |
237 | } | |
238 | ||
239 | static void set_power_saving_task_num(unsigned int num) | |
240 | { | |
241 | if (num > ps_tsk_num) { | |
242 | while (ps_tsk_num < num) { | |
243 | if (create_power_saving_task()) | |
244 | return; | |
245 | } | |
246 | } else if (num < ps_tsk_num) { | |
247 | while (ps_tsk_num > num) | |
248 | destroy_power_saving_task(); | |
249 | } | |
250 | } | |
251 | ||
3b8cb427 | 252 | static void acpi_pad_idle_cpus(unsigned int num_cpus) |
8e0af514 SL |
253 | { |
254 | get_online_cpus(); | |
255 | ||
256 | num_cpus = min_t(unsigned int, num_cpus, num_online_cpus()); | |
257 | set_power_saving_task_num(num_cpus); | |
258 | ||
259 | put_online_cpus(); | |
8e0af514 SL |
260 | } |
261 | ||
262 | static uint32_t acpi_pad_idle_cpus_num(void) | |
263 | { | |
264 | return ps_tsk_num; | |
265 | } | |
266 | ||
267 | static ssize_t acpi_pad_rrtime_store(struct device *dev, | |
268 | struct device_attribute *attr, const char *buf, size_t count) | |
269 | { | |
270 | unsigned long num; | |
73d4511a | 271 | if (kstrtoul(buf, 0, &num)) |
8e0af514 SL |
272 | return -EINVAL; |
273 | if (num < 1 || num >= 100) | |
274 | return -EINVAL; | |
275 | mutex_lock(&isolated_cpus_lock); | |
276 | round_robin_time = num; | |
277 | mutex_unlock(&isolated_cpus_lock); | |
278 | return count; | |
279 | } | |
280 | ||
281 | static ssize_t acpi_pad_rrtime_show(struct device *dev, | |
282 | struct device_attribute *attr, char *buf) | |
283 | { | |
32297abd | 284 | return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time); |
8e0af514 SL |
285 | } |
286 | static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR, | |
287 | acpi_pad_rrtime_show, | |
288 | acpi_pad_rrtime_store); | |
289 | ||
290 | static ssize_t acpi_pad_idlepct_store(struct device *dev, | |
291 | struct device_attribute *attr, const char *buf, size_t count) | |
292 | { | |
293 | unsigned long num; | |
73d4511a | 294 | if (kstrtoul(buf, 0, &num)) |
8e0af514 SL |
295 | return -EINVAL; |
296 | if (num < 1 || num >= 100) | |
297 | return -EINVAL; | |
298 | mutex_lock(&isolated_cpus_lock); | |
299 | idle_pct = num; | |
300 | mutex_unlock(&isolated_cpus_lock); | |
301 | return count; | |
302 | } | |
303 | ||
304 | static ssize_t acpi_pad_idlepct_show(struct device *dev, | |
305 | struct device_attribute *attr, char *buf) | |
306 | { | |
32297abd | 307 | return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct); |
8e0af514 SL |
308 | } |
309 | static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR, | |
310 | acpi_pad_idlepct_show, | |
311 | acpi_pad_idlepct_store); | |
312 | ||
313 | static ssize_t acpi_pad_idlecpus_store(struct device *dev, | |
314 | struct device_attribute *attr, const char *buf, size_t count) | |
315 | { | |
316 | unsigned long num; | |
73d4511a | 317 | if (kstrtoul(buf, 0, &num)) |
8e0af514 SL |
318 | return -EINVAL; |
319 | mutex_lock(&isolated_cpus_lock); | |
320 | acpi_pad_idle_cpus(num); | |
321 | mutex_unlock(&isolated_cpus_lock); | |
322 | return count; | |
323 | } | |
324 | ||
325 | static ssize_t acpi_pad_idlecpus_show(struct device *dev, | |
326 | struct device_attribute *attr, char *buf) | |
327 | { | |
5aaba363 SH |
328 | return cpumap_print_to_pagebuf(false, buf, |
329 | to_cpumask(pad_busy_cpus_bits)); | |
8e0af514 | 330 | } |
5aaba363 | 331 | |
8e0af514 SL |
332 | static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR, |
333 | acpi_pad_idlecpus_show, | |
334 | acpi_pad_idlecpus_store); | |
335 | ||
336 | static int acpi_pad_add_sysfs(struct acpi_device *device) | |
337 | { | |
338 | int result; | |
339 | ||
340 | result = device_create_file(&device->dev, &dev_attr_idlecpus); | |
341 | if (result) | |
342 | return -ENODEV; | |
343 | result = device_create_file(&device->dev, &dev_attr_idlepct); | |
344 | if (result) { | |
345 | device_remove_file(&device->dev, &dev_attr_idlecpus); | |
346 | return -ENODEV; | |
347 | } | |
348 | result = device_create_file(&device->dev, &dev_attr_rrtime); | |
349 | if (result) { | |
350 | device_remove_file(&device->dev, &dev_attr_idlecpus); | |
351 | device_remove_file(&device->dev, &dev_attr_idlepct); | |
352 | return -ENODEV; | |
353 | } | |
354 | return 0; | |
355 | } | |
356 | ||
357 | static void acpi_pad_remove_sysfs(struct acpi_device *device) | |
358 | { | |
359 | device_remove_file(&device->dev, &dev_attr_idlecpus); | |
360 | device_remove_file(&device->dev, &dev_attr_idlepct); | |
361 | device_remove_file(&device->dev, &dev_attr_rrtime); | |
362 | } | |
363 | ||
c9ad8e06 LB |
364 | /* |
365 | * Query firmware how many CPUs should be idle | |
366 | * return -1 on failure | |
367 | */ | |
368 | static int acpi_pad_pur(acpi_handle handle) | |
8e0af514 SL |
369 | { |
370 | struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL}; | |
8e0af514 | 371 | union acpi_object *package; |
c9ad8e06 | 372 | int num = -1; |
8e0af514 | 373 | |
3b8cb427 | 374 | if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer))) |
c9ad8e06 | 375 | return num; |
3b8cb427 CG |
376 | |
377 | if (!buffer.length || !buffer.pointer) | |
c9ad8e06 | 378 | return num; |
3b8cb427 | 379 | |
8e0af514 | 380 | package = buffer.pointer; |
c9ad8e06 LB |
381 | |
382 | if (package->type == ACPI_TYPE_PACKAGE && | |
383 | package->package.count == 2 && | |
384 | package->package.elements[0].integer.value == 1) /* rev 1 */ | |
385 | ||
386 | num = package->package.elements[1].integer.value; | |
387 | ||
8e0af514 | 388 | kfree(buffer.pointer); |
c9ad8e06 | 389 | return num; |
8e0af514 SL |
390 | } |
391 | ||
8e0af514 SL |
392 | static void acpi_pad_handle_notify(acpi_handle handle) |
393 | { | |
3b8cb427 | 394 | int num_cpus; |
8e0af514 | 395 | uint32_t idle_cpus; |
8b296d94 JL |
396 | struct acpi_buffer param = { |
397 | .length = 4, | |
398 | .pointer = (void *)&idle_cpus, | |
399 | }; | |
8e0af514 SL |
400 | |
401 | mutex_lock(&isolated_cpus_lock); | |
c9ad8e06 LB |
402 | num_cpus = acpi_pad_pur(handle); |
403 | if (num_cpus < 0) { | |
8e0af514 SL |
404 | mutex_unlock(&isolated_cpus_lock); |
405 | return; | |
406 | } | |
3b8cb427 | 407 | acpi_pad_idle_cpus(num_cpus); |
8e0af514 | 408 | idle_cpus = acpi_pad_idle_cpus_num(); |
8b296d94 | 409 | acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m); |
8e0af514 SL |
410 | mutex_unlock(&isolated_cpus_lock); |
411 | } | |
412 | ||
413 | static void acpi_pad_notify(acpi_handle handle, u32 event, | |
414 | void *data) | |
415 | { | |
416 | struct acpi_device *device = data; | |
417 | ||
418 | switch (event) { | |
419 | case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: | |
420 | acpi_pad_handle_notify(handle); | |
8e0af514 SL |
421 | acpi_bus_generate_netlink_event(device->pnp.device_class, |
422 | dev_name(&device->dev), event, 0); | |
423 | break; | |
424 | default: | |
73d4511a | 425 | pr_warn("Unsupported event [0x%x]\n", event); |
8e0af514 SL |
426 | break; |
427 | } | |
428 | } | |
429 | ||
430 | static int acpi_pad_add(struct acpi_device *device) | |
431 | { | |
432 | acpi_status status; | |
433 | ||
434 | strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); | |
435 | strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); | |
436 | ||
437 | if (acpi_pad_add_sysfs(device)) | |
438 | return -ENODEV; | |
439 | ||
440 | status = acpi_install_notify_handler(device->handle, | |
441 | ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); | |
442 | if (ACPI_FAILURE(status)) { | |
443 | acpi_pad_remove_sysfs(device); | |
444 | return -ENODEV; | |
445 | } | |
446 | ||
447 | return 0; | |
448 | } | |
449 | ||
51fac838 | 450 | static int acpi_pad_remove(struct acpi_device *device) |
8e0af514 SL |
451 | { |
452 | mutex_lock(&isolated_cpus_lock); | |
453 | acpi_pad_idle_cpus(0); | |
454 | mutex_unlock(&isolated_cpus_lock); | |
455 | ||
456 | acpi_remove_notify_handler(device->handle, | |
457 | ACPI_DEVICE_NOTIFY, acpi_pad_notify); | |
458 | acpi_pad_remove_sysfs(device); | |
459 | return 0; | |
460 | } | |
461 | ||
462 | static const struct acpi_device_id pad_device_ids[] = { | |
463 | {"ACPI000C", 0}, | |
464 | {"", 0}, | |
465 | }; | |
466 | MODULE_DEVICE_TABLE(acpi, pad_device_ids); | |
467 | ||
468 | static struct acpi_driver acpi_pad_driver = { | |
469 | .name = "processor_aggregator", | |
470 | .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, | |
471 | .ids = pad_device_ids, | |
472 | .ops = { | |
473 | .add = acpi_pad_add, | |
474 | .remove = acpi_pad_remove, | |
475 | }, | |
476 | }; | |
477 | ||
478 | static int __init acpi_pad_init(void) | |
479 | { | |
480 | power_saving_mwait_init(); | |
481 | if (power_saving_mwait_eax == 0) | |
482 | return -EINVAL; | |
483 | ||
484 | return acpi_bus_register_driver(&acpi_pad_driver); | |
485 | } | |
486 | ||
487 | static void __exit acpi_pad_exit(void) | |
488 | { | |
489 | acpi_bus_unregister_driver(&acpi_pad_driver); | |
490 | } | |
491 | ||
492 | module_init(acpi_pad_init); | |
493 | module_exit(acpi_pad_exit); | |
494 | MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>"); | |
495 | MODULE_DESCRIPTION("ACPI Processor Aggregator Driver"); | |
496 | MODULE_LICENSE("GPL"); |