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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 | * | |
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> | |
5a0e3ad6 | 30 | #include <linux/slab.h> |
8b48463f | 31 | #include <linux/acpi.h> |
bc83cccc | 32 | #include <asm/mwait.h> |
8e0af514 | 33 | |
a40770a9 | 34 | #define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad" |
8e0af514 SL |
35 | #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator" |
36 | #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80 | |
37 | static DEFINE_MUTEX(isolated_cpus_lock); | |
5f160126 | 38 | static DEFINE_MUTEX(round_robin_lock); |
8e0af514 | 39 | |
8e0af514 | 40 | static unsigned long power_saving_mwait_eax; |
0dc698b9 VP |
41 | |
42 | static unsigned char tsc_detected_unstable; | |
43 | static unsigned char tsc_marked_unstable; | |
8aa4b14e CG |
44 | static unsigned char lapic_detected_unstable; |
45 | static unsigned char lapic_marked_unstable; | |
0dc698b9 | 46 | |
8e0af514 SL |
47 | static void power_saving_mwait_init(void) |
48 | { | |
49 | unsigned int eax, ebx, ecx, edx; | |
50 | unsigned int highest_cstate = 0; | |
51 | unsigned int highest_subcstate = 0; | |
52 | int i; | |
53 | ||
54 | if (!boot_cpu_has(X86_FEATURE_MWAIT)) | |
55 | return; | |
56 | if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF) | |
57 | return; | |
58 | ||
59 | cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx); | |
60 | ||
61 | if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) || | |
62 | !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) | |
63 | return; | |
64 | ||
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; | |
70 | } | |
71 | } | |
72 | power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) | | |
73 | (highest_subcstate - 1); | |
74 | ||
592913ec | 75 | #if defined(CONFIG_X86) |
8e0af514 SL |
76 | switch (boot_cpu_data.x86_vendor) { |
77 | case X86_VENDOR_AMD: | |
78 | case X86_VENDOR_INTEL: | |
79 | /* | |
80 | * AMD Fam10h TSC will tick in all | |
81 | * C/P/S0/S1 states when this bit is set. | |
82 | */ | |
8aa4b14e CG |
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; | |
8e0af514 | 88 | default: |
8aa4b14e | 89 | /* TSC & LAPIC could halt in idle */ |
0dc698b9 | 90 | tsc_detected_unstable = 1; |
8aa4b14e | 91 | lapic_detected_unstable = 1; |
8e0af514 SL |
92 | } |
93 | #endif | |
94 | } | |
95 | ||
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) | |
100 | { | |
101 | struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); | |
102 | cpumask_var_t tmp; | |
103 | int cpu; | |
f67538f8 AM |
104 | unsigned long min_weight = -1; |
105 | unsigned long uninitialized_var(preferred_cpu); | |
8e0af514 SL |
106 | |
107 | if (!alloc_cpumask_var(&tmp, GFP_KERNEL)) | |
108 | return; | |
109 | ||
5f160126 | 110 | mutex_lock(&round_robin_lock); |
8e0af514 SL |
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)) { | |
5f160126 | 119 | mutex_unlock(&round_robin_lock); |
8e0af514 SL |
120 | return; |
121 | } | |
122 | for_each_cpu(cpu, tmp) { | |
123 | if (cpu_weight[cpu] < min_weight) { | |
124 | min_weight = cpu_weight[cpu]; | |
125 | preferred_cpu = cpu; | |
126 | } | |
127 | } | |
128 | ||
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]++; | |
5f160126 | 134 | mutex_unlock(&round_robin_lock); |
8e0af514 SL |
135 | |
136 | set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu)); | |
137 | } | |
138 | ||
139 | static void exit_round_robin(unsigned int tsk_index) | |
140 | { | |
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; | |
144 | } | |
145 | ||
146 | static unsigned int idle_pct = 5; /* percentage */ | |
fa7584e1 | 147 | static unsigned int round_robin_time = 1; /* second */ |
8e0af514 SL |
148 | static int power_saving_thread(void *data) |
149 | { | |
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; | |
154 | ||
155 | sched_setscheduler(current, SCHED_RR, ¶m); | |
156 | ||
157 | while (!kthread_should_stop()) { | |
158 | int cpu; | |
4ff248f3 | 159 | unsigned long expire_time; |
8e0af514 SL |
160 | |
161 | try_to_freeze(); | |
162 | ||
163 | /* round robin to cpus */ | |
4ff248f3 MS |
164 | expire_time = last_jiffies + round_robin_time * HZ; |
165 | if (time_before(expire_time, jiffies)) { | |
8e0af514 SL |
166 | last_jiffies = jiffies; |
167 | round_robin_cpu(tsk_index); | |
168 | } | |
169 | ||
170 | do_sleep = 0; | |
171 | ||
8e0af514 SL |
172 | expire_time = jiffies + HZ * (100 - idle_pct) / 100; |
173 | ||
174 | while (!need_resched()) { | |
0dc698b9 VP |
175 | if (tsc_detected_unstable && !tsc_marked_unstable) { |
176 | /* TSC could halt in idle, so notify users */ | |
177 | mark_tsc_unstable("TSC halts in idle"); | |
178 | tsc_marked_unstable = 1; | |
179 | } | |
8aa4b14e CG |
180 | if (lapic_detected_unstable && !lapic_marked_unstable) { |
181 | int i; | |
182 | /* LAPIC could halt in idle, so notify users */ | |
183 | for_each_online_cpu(i) | |
184 | clockevents_notify( | |
185 | CLOCK_EVT_NOTIFY_BROADCAST_ON, | |
186 | &i); | |
187 | lapic_marked_unstable = 1; | |
188 | } | |
8e0af514 SL |
189 | local_irq_disable(); |
190 | cpu = smp_processor_id(); | |
8aa4b14e CG |
191 | if (lapic_marked_unstable) |
192 | clockevents_notify( | |
193 | CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu); | |
8e0af514 SL |
194 | stop_critical_timings(); |
195 | ||
16824255 | 196 | mwait_idle_with_hints(power_saving_mwait_eax, 1); |
8e0af514 SL |
197 | |
198 | start_critical_timings(); | |
8aa4b14e CG |
199 | if (lapic_marked_unstable) |
200 | clockevents_notify( | |
201 | CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu); | |
8e0af514 SL |
202 | local_irq_enable(); |
203 | ||
4ff248f3 | 204 | if (time_before(expire_time, jiffies)) { |
8e0af514 SL |
205 | do_sleep = 1; |
206 | break; | |
207 | } | |
208 | } | |
209 | ||
8e0af514 SL |
210 | /* |
211 | * current sched_rt has threshold for rt task running time. | |
212 | * When a rt task uses 95% CPU time, the rt thread will be | |
213 | * scheduled out for 5% CPU time to not starve other tasks. But | |
214 | * the mechanism only works when all CPUs have RT task running, | |
215 | * as if one CPU hasn't RT task, RT task from other CPUs will | |
216 | * borrow CPU time from this CPU and cause RT task use > 95% | |
3b8cb427 | 217 | * CPU time. To make 'avoid starvation' work, takes a nap here. |
8e0af514 | 218 | */ |
5b59c69e | 219 | if (unlikely(do_sleep)) |
8e0af514 | 220 | schedule_timeout_killable(HZ * idle_pct / 100); |
5b59c69e TC |
221 | |
222 | /* If an external event has set the need_resched flag, then | |
223 | * we need to deal with it, or this loop will continue to | |
224 | * spin without calling __mwait(). | |
225 | */ | |
226 | if (unlikely(need_resched())) | |
227 | schedule(); | |
8e0af514 SL |
228 | } |
229 | ||
230 | exit_round_robin(tsk_index); | |
231 | return 0; | |
232 | } | |
233 | ||
234 | static struct task_struct *ps_tsks[NR_CPUS]; | |
235 | static unsigned int ps_tsk_num; | |
236 | static int create_power_saving_task(void) | |
237 | { | |
5d7e4386 | 238 | int rc; |
3b8cb427 | 239 | |
8e0af514 SL |
240 | ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread, |
241 | (void *)(unsigned long)ps_tsk_num, | |
150ed86f | 242 | "acpi_pad/%d", ps_tsk_num); |
5d7e4386 RR |
243 | |
244 | if (IS_ERR(ps_tsks[ps_tsk_num])) { | |
245 | rc = PTR_ERR(ps_tsks[ps_tsk_num]); | |
3b8cb427 | 246 | ps_tsks[ps_tsk_num] = NULL; |
5d7e4386 RR |
247 | } else { |
248 | rc = 0; | |
249 | ps_tsk_num++; | |
250 | } | |
3b8cb427 CG |
251 | |
252 | return rc; | |
8e0af514 SL |
253 | } |
254 | ||
255 | static void destroy_power_saving_task(void) | |
256 | { | |
257 | if (ps_tsk_num > 0) { | |
258 | ps_tsk_num--; | |
259 | kthread_stop(ps_tsks[ps_tsk_num]); | |
3b8cb427 | 260 | ps_tsks[ps_tsk_num] = NULL; |
8e0af514 SL |
261 | } |
262 | } | |
263 | ||
264 | static void set_power_saving_task_num(unsigned int num) | |
265 | { | |
266 | if (num > ps_tsk_num) { | |
267 | while (ps_tsk_num < num) { | |
268 | if (create_power_saving_task()) | |
269 | return; | |
270 | } | |
271 | } else if (num < ps_tsk_num) { | |
272 | while (ps_tsk_num > num) | |
273 | destroy_power_saving_task(); | |
274 | } | |
275 | } | |
276 | ||
3b8cb427 | 277 | static void acpi_pad_idle_cpus(unsigned int num_cpus) |
8e0af514 SL |
278 | { |
279 | get_online_cpus(); | |
280 | ||
281 | num_cpus = min_t(unsigned int, num_cpus, num_online_cpus()); | |
282 | set_power_saving_task_num(num_cpus); | |
283 | ||
284 | put_online_cpus(); | |
8e0af514 SL |
285 | } |
286 | ||
287 | static uint32_t acpi_pad_idle_cpus_num(void) | |
288 | { | |
289 | return ps_tsk_num; | |
290 | } | |
291 | ||
292 | static ssize_t acpi_pad_rrtime_store(struct device *dev, | |
293 | struct device_attribute *attr, const char *buf, size_t count) | |
294 | { | |
295 | unsigned long num; | |
73d4511a | 296 | if (kstrtoul(buf, 0, &num)) |
8e0af514 SL |
297 | return -EINVAL; |
298 | if (num < 1 || num >= 100) | |
299 | return -EINVAL; | |
300 | mutex_lock(&isolated_cpus_lock); | |
301 | round_robin_time = num; | |
302 | mutex_unlock(&isolated_cpus_lock); | |
303 | return count; | |
304 | } | |
305 | ||
306 | static ssize_t acpi_pad_rrtime_show(struct device *dev, | |
307 | struct device_attribute *attr, char *buf) | |
308 | { | |
32297abd | 309 | return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time); |
8e0af514 SL |
310 | } |
311 | static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR, | |
312 | acpi_pad_rrtime_show, | |
313 | acpi_pad_rrtime_store); | |
314 | ||
315 | static ssize_t acpi_pad_idlepct_store(struct device *dev, | |
316 | struct device_attribute *attr, const char *buf, size_t count) | |
317 | { | |
318 | unsigned long num; | |
73d4511a | 319 | if (kstrtoul(buf, 0, &num)) |
8e0af514 SL |
320 | return -EINVAL; |
321 | if (num < 1 || num >= 100) | |
322 | return -EINVAL; | |
323 | mutex_lock(&isolated_cpus_lock); | |
324 | idle_pct = num; | |
325 | mutex_unlock(&isolated_cpus_lock); | |
326 | return count; | |
327 | } | |
328 | ||
329 | static ssize_t acpi_pad_idlepct_show(struct device *dev, | |
330 | struct device_attribute *attr, char *buf) | |
331 | { | |
32297abd | 332 | return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct); |
8e0af514 SL |
333 | } |
334 | static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR, | |
335 | acpi_pad_idlepct_show, | |
336 | acpi_pad_idlepct_store); | |
337 | ||
338 | static ssize_t acpi_pad_idlecpus_store(struct device *dev, | |
339 | struct device_attribute *attr, const char *buf, size_t count) | |
340 | { | |
341 | unsigned long num; | |
73d4511a | 342 | if (kstrtoul(buf, 0, &num)) |
8e0af514 SL |
343 | return -EINVAL; |
344 | mutex_lock(&isolated_cpus_lock); | |
345 | acpi_pad_idle_cpus(num); | |
346 | mutex_unlock(&isolated_cpus_lock); | |
347 | return count; | |
348 | } | |
349 | ||
350 | static ssize_t acpi_pad_idlecpus_show(struct device *dev, | |
351 | struct device_attribute *attr, char *buf) | |
352 | { | |
5aaba363 SH |
353 | return cpumap_print_to_pagebuf(false, buf, |
354 | to_cpumask(pad_busy_cpus_bits)); | |
8e0af514 | 355 | } |
5aaba363 | 356 | |
8e0af514 SL |
357 | static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR, |
358 | acpi_pad_idlecpus_show, | |
359 | acpi_pad_idlecpus_store); | |
360 | ||
361 | static int acpi_pad_add_sysfs(struct acpi_device *device) | |
362 | { | |
363 | int result; | |
364 | ||
365 | result = device_create_file(&device->dev, &dev_attr_idlecpus); | |
366 | if (result) | |
367 | return -ENODEV; | |
368 | result = device_create_file(&device->dev, &dev_attr_idlepct); | |
369 | if (result) { | |
370 | device_remove_file(&device->dev, &dev_attr_idlecpus); | |
371 | return -ENODEV; | |
372 | } | |
373 | result = device_create_file(&device->dev, &dev_attr_rrtime); | |
374 | if (result) { | |
375 | device_remove_file(&device->dev, &dev_attr_idlecpus); | |
376 | device_remove_file(&device->dev, &dev_attr_idlepct); | |
377 | return -ENODEV; | |
378 | } | |
379 | return 0; | |
380 | } | |
381 | ||
382 | static void acpi_pad_remove_sysfs(struct acpi_device *device) | |
383 | { | |
384 | device_remove_file(&device->dev, &dev_attr_idlecpus); | |
385 | device_remove_file(&device->dev, &dev_attr_idlepct); | |
386 | device_remove_file(&device->dev, &dev_attr_rrtime); | |
387 | } | |
388 | ||
c9ad8e06 LB |
389 | /* |
390 | * Query firmware how many CPUs should be idle | |
391 | * return -1 on failure | |
392 | */ | |
393 | static int acpi_pad_pur(acpi_handle handle) | |
8e0af514 SL |
394 | { |
395 | struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL}; | |
8e0af514 | 396 | union acpi_object *package; |
c9ad8e06 | 397 | int num = -1; |
8e0af514 | 398 | |
3b8cb427 | 399 | if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer))) |
c9ad8e06 | 400 | return num; |
3b8cb427 CG |
401 | |
402 | if (!buffer.length || !buffer.pointer) | |
c9ad8e06 | 403 | return num; |
3b8cb427 | 404 | |
8e0af514 | 405 | package = buffer.pointer; |
c9ad8e06 LB |
406 | |
407 | if (package->type == ACPI_TYPE_PACKAGE && | |
408 | package->package.count == 2 && | |
409 | package->package.elements[0].integer.value == 1) /* rev 1 */ | |
410 | ||
411 | num = package->package.elements[1].integer.value; | |
412 | ||
8e0af514 | 413 | kfree(buffer.pointer); |
c9ad8e06 | 414 | return num; |
8e0af514 SL |
415 | } |
416 | ||
8e0af514 SL |
417 | static void acpi_pad_handle_notify(acpi_handle handle) |
418 | { | |
3b8cb427 | 419 | int num_cpus; |
8e0af514 | 420 | uint32_t idle_cpus; |
8b296d94 JL |
421 | struct acpi_buffer param = { |
422 | .length = 4, | |
423 | .pointer = (void *)&idle_cpus, | |
424 | }; | |
8e0af514 SL |
425 | |
426 | mutex_lock(&isolated_cpus_lock); | |
c9ad8e06 LB |
427 | num_cpus = acpi_pad_pur(handle); |
428 | if (num_cpus < 0) { | |
8e0af514 SL |
429 | mutex_unlock(&isolated_cpus_lock); |
430 | return; | |
431 | } | |
3b8cb427 | 432 | acpi_pad_idle_cpus(num_cpus); |
8e0af514 | 433 | idle_cpus = acpi_pad_idle_cpus_num(); |
8b296d94 | 434 | acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m); |
8e0af514 SL |
435 | mutex_unlock(&isolated_cpus_lock); |
436 | } | |
437 | ||
438 | static void acpi_pad_notify(acpi_handle handle, u32 event, | |
439 | void *data) | |
440 | { | |
441 | struct acpi_device *device = data; | |
442 | ||
443 | switch (event) { | |
444 | case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: | |
445 | acpi_pad_handle_notify(handle); | |
8e0af514 SL |
446 | acpi_bus_generate_netlink_event(device->pnp.device_class, |
447 | dev_name(&device->dev), event, 0); | |
448 | break; | |
449 | default: | |
73d4511a | 450 | pr_warn("Unsupported event [0x%x]\n", event); |
8e0af514 SL |
451 | break; |
452 | } | |
453 | } | |
454 | ||
455 | static int acpi_pad_add(struct acpi_device *device) | |
456 | { | |
457 | acpi_status status; | |
458 | ||
459 | strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); | |
460 | strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); | |
461 | ||
462 | if (acpi_pad_add_sysfs(device)) | |
463 | return -ENODEV; | |
464 | ||
465 | status = acpi_install_notify_handler(device->handle, | |
466 | ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); | |
467 | if (ACPI_FAILURE(status)) { | |
468 | acpi_pad_remove_sysfs(device); | |
469 | return -ENODEV; | |
470 | } | |
471 | ||
472 | return 0; | |
473 | } | |
474 | ||
51fac838 | 475 | static int acpi_pad_remove(struct acpi_device *device) |
8e0af514 SL |
476 | { |
477 | mutex_lock(&isolated_cpus_lock); | |
478 | acpi_pad_idle_cpus(0); | |
479 | mutex_unlock(&isolated_cpus_lock); | |
480 | ||
481 | acpi_remove_notify_handler(device->handle, | |
482 | ACPI_DEVICE_NOTIFY, acpi_pad_notify); | |
483 | acpi_pad_remove_sysfs(device); | |
484 | return 0; | |
485 | } | |
486 | ||
487 | static const struct acpi_device_id pad_device_ids[] = { | |
488 | {"ACPI000C", 0}, | |
489 | {"", 0}, | |
490 | }; | |
491 | MODULE_DEVICE_TABLE(acpi, pad_device_ids); | |
492 | ||
493 | static struct acpi_driver acpi_pad_driver = { | |
494 | .name = "processor_aggregator", | |
495 | .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, | |
496 | .ids = pad_device_ids, | |
497 | .ops = { | |
498 | .add = acpi_pad_add, | |
499 | .remove = acpi_pad_remove, | |
500 | }, | |
501 | }; | |
502 | ||
503 | static int __init acpi_pad_init(void) | |
504 | { | |
505 | power_saving_mwait_init(); | |
506 | if (power_saving_mwait_eax == 0) | |
507 | return -EINVAL; | |
508 | ||
509 | return acpi_bus_register_driver(&acpi_pad_driver); | |
510 | } | |
511 | ||
512 | static void __exit acpi_pad_exit(void) | |
513 | { | |
514 | acpi_bus_unregister_driver(&acpi_pad_driver); | |
515 | } | |
516 | ||
517 | module_init(acpi_pad_init); | |
518 | module_exit(acpi_pad_exit); | |
519 | MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>"); | |
520 | MODULE_DESCRIPTION("ACPI Processor Aggregator Driver"); | |
521 | MODULE_LICENSE("GPL"); |