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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> |
8e0af514 SL |
31 | #include <acpi/acpi_bus.h> |
32 | #include <acpi/acpi_drivers.h> | |
bc83cccc | 33 | #include <asm/mwait.h> |
8e0af514 | 34 | |
a40770a9 | 35 | #define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad" |
8e0af514 SL |
36 | #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator" |
37 | #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80 | |
38 | static DEFINE_MUTEX(isolated_cpus_lock); | |
5f160126 | 39 | static DEFINE_MUTEX(round_robin_lock); |
8e0af514 | 40 | |
8e0af514 | 41 | static unsigned long power_saving_mwait_eax; |
0dc698b9 VP |
42 | |
43 | static unsigned char tsc_detected_unstable; | |
44 | static unsigned char tsc_marked_unstable; | |
8aa4b14e CG |
45 | static unsigned char lapic_detected_unstable; |
46 | static unsigned char lapic_marked_unstable; | |
0dc698b9 | 47 | |
8e0af514 SL |
48 | static void power_saving_mwait_init(void) |
49 | { | |
50 | unsigned int eax, ebx, ecx, edx; | |
51 | unsigned int highest_cstate = 0; | |
52 | unsigned int highest_subcstate = 0; | |
53 | int i; | |
54 | ||
55 | if (!boot_cpu_has(X86_FEATURE_MWAIT)) | |
56 | return; | |
57 | if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF) | |
58 | return; | |
59 | ||
60 | cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx); | |
61 | ||
62 | if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) || | |
63 | !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) | |
64 | return; | |
65 | ||
66 | edx >>= MWAIT_SUBSTATE_SIZE; | |
67 | for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) { | |
68 | if (edx & MWAIT_SUBSTATE_MASK) { | |
69 | highest_cstate = i; | |
70 | highest_subcstate = edx & MWAIT_SUBSTATE_MASK; | |
71 | } | |
72 | } | |
73 | power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) | | |
74 | (highest_subcstate - 1); | |
75 | ||
592913ec | 76 | #if defined(CONFIG_X86) |
8e0af514 SL |
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 | */ | |
8aa4b14e CG |
84 | if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) |
85 | tsc_detected_unstable = 1; | |
86 | if (!boot_cpu_has(X86_FEATURE_ARAT)) | |
87 | lapic_detected_unstable = 1; | |
88 | break; | |
8e0af514 | 89 | default: |
8aa4b14e | 90 | /* TSC & LAPIC could halt in idle */ |
0dc698b9 | 91 | tsc_detected_unstable = 1; |
8aa4b14e | 92 | lapic_detected_unstable = 1; |
8e0af514 SL |
93 | } |
94 | #endif | |
95 | } | |
96 | ||
97 | static unsigned long cpu_weight[NR_CPUS]; | |
98 | static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1}; | |
99 | static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS); | |
100 | static void round_robin_cpu(unsigned int tsk_index) | |
101 | { | |
102 | struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); | |
103 | cpumask_var_t tmp; | |
104 | int cpu; | |
f67538f8 AM |
105 | unsigned long min_weight = -1; |
106 | unsigned long uninitialized_var(preferred_cpu); | |
8e0af514 SL |
107 | |
108 | if (!alloc_cpumask_var(&tmp, GFP_KERNEL)) | |
109 | return; | |
110 | ||
5f160126 | 111 | mutex_lock(&round_robin_lock); |
8e0af514 SL |
112 | cpumask_clear(tmp); |
113 | for_each_cpu(cpu, pad_busy_cpus) | |
114 | cpumask_or(tmp, tmp, topology_thread_cpumask(cpu)); | |
115 | cpumask_andnot(tmp, cpu_online_mask, tmp); | |
116 | /* avoid HT sibilings if possible */ | |
117 | if (cpumask_empty(tmp)) | |
118 | cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus); | |
119 | if (cpumask_empty(tmp)) { | |
5f160126 | 120 | mutex_unlock(&round_robin_lock); |
8e0af514 SL |
121 | return; |
122 | } | |
123 | for_each_cpu(cpu, tmp) { | |
124 | if (cpu_weight[cpu] < min_weight) { | |
125 | min_weight = cpu_weight[cpu]; | |
126 | preferred_cpu = cpu; | |
127 | } | |
128 | } | |
129 | ||
130 | if (tsk_in_cpu[tsk_index] != -1) | |
131 | cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); | |
132 | tsk_in_cpu[tsk_index] = preferred_cpu; | |
133 | cpumask_set_cpu(preferred_cpu, pad_busy_cpus); | |
134 | cpu_weight[preferred_cpu]++; | |
5f160126 | 135 | mutex_unlock(&round_robin_lock); |
8e0af514 SL |
136 | |
137 | set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu)); | |
138 | } | |
139 | ||
140 | static void exit_round_robin(unsigned int tsk_index) | |
141 | { | |
142 | struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); | |
143 | cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); | |
144 | tsk_in_cpu[tsk_index] = -1; | |
145 | } | |
146 | ||
147 | static unsigned int idle_pct = 5; /* percentage */ | |
148 | static unsigned int round_robin_time = 10; /* second */ | |
149 | static int power_saving_thread(void *data) | |
150 | { | |
151 | struct sched_param param = {.sched_priority = 1}; | |
152 | int do_sleep; | |
153 | unsigned int tsk_index = (unsigned long)data; | |
154 | u64 last_jiffies = 0; | |
155 | ||
156 | sched_setscheduler(current, SCHED_RR, ¶m); | |
157 | ||
158 | while (!kthread_should_stop()) { | |
159 | int cpu; | |
160 | u64 expire_time; | |
161 | ||
162 | try_to_freeze(); | |
163 | ||
164 | /* round robin to cpus */ | |
165 | if (last_jiffies + round_robin_time * HZ < jiffies) { | |
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 | ||
196 | __monitor((void *)¤t_thread_info()->flags, 0, 0); | |
197 | smp_mb(); | |
198 | if (!need_resched()) | |
199 | __mwait(power_saving_mwait_eax, 1); | |
200 | ||
201 | start_critical_timings(); | |
8aa4b14e CG |
202 | if (lapic_marked_unstable) |
203 | clockevents_notify( | |
204 | CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu); | |
8e0af514 SL |
205 | local_irq_enable(); |
206 | ||
207 | if (jiffies > expire_time) { | |
208 | do_sleep = 1; | |
209 | break; | |
210 | } | |
211 | } | |
212 | ||
8e0af514 SL |
213 | /* |
214 | * current sched_rt has threshold for rt task running time. | |
215 | * When a rt task uses 95% CPU time, the rt thread will be | |
216 | * scheduled out for 5% CPU time to not starve other tasks. But | |
217 | * the mechanism only works when all CPUs have RT task running, | |
218 | * as if one CPU hasn't RT task, RT task from other CPUs will | |
219 | * borrow CPU time from this CPU and cause RT task use > 95% | |
3b8cb427 | 220 | * CPU time. To make 'avoid starvation' work, takes a nap here. |
8e0af514 SL |
221 | */ |
222 | if (do_sleep) | |
223 | schedule_timeout_killable(HZ * idle_pct / 100); | |
224 | } | |
225 | ||
226 | exit_round_robin(tsk_index); | |
227 | return 0; | |
228 | } | |
229 | ||
230 | static struct task_struct *ps_tsks[NR_CPUS]; | |
231 | static unsigned int ps_tsk_num; | |
232 | static int create_power_saving_task(void) | |
233 | { | |
3b8cb427 CG |
234 | int rc = -ENOMEM; |
235 | ||
8e0af514 SL |
236 | ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread, |
237 | (void *)(unsigned long)ps_tsk_num, | |
238 | "power_saving/%d", ps_tsk_num); | |
3b8cb427 CG |
239 | rc = IS_ERR(ps_tsks[ps_tsk_num]) ? PTR_ERR(ps_tsks[ps_tsk_num]) : 0; |
240 | if (!rc) | |
8e0af514 | 241 | ps_tsk_num++; |
3b8cb427 CG |
242 | else |
243 | ps_tsks[ps_tsk_num] = NULL; | |
244 | ||
245 | return rc; | |
8e0af514 SL |
246 | } |
247 | ||
248 | static void destroy_power_saving_task(void) | |
249 | { | |
250 | if (ps_tsk_num > 0) { | |
251 | ps_tsk_num--; | |
252 | kthread_stop(ps_tsks[ps_tsk_num]); | |
3b8cb427 | 253 | ps_tsks[ps_tsk_num] = NULL; |
8e0af514 SL |
254 | } |
255 | } | |
256 | ||
257 | static void set_power_saving_task_num(unsigned int num) | |
258 | { | |
259 | if (num > ps_tsk_num) { | |
260 | while (ps_tsk_num < num) { | |
261 | if (create_power_saving_task()) | |
262 | return; | |
263 | } | |
264 | } else if (num < ps_tsk_num) { | |
265 | while (ps_tsk_num > num) | |
266 | destroy_power_saving_task(); | |
267 | } | |
268 | } | |
269 | ||
3b8cb427 | 270 | static void acpi_pad_idle_cpus(unsigned int num_cpus) |
8e0af514 SL |
271 | { |
272 | get_online_cpus(); | |
273 | ||
274 | num_cpus = min_t(unsigned int, num_cpus, num_online_cpus()); | |
275 | set_power_saving_task_num(num_cpus); | |
276 | ||
277 | put_online_cpus(); | |
8e0af514 SL |
278 | } |
279 | ||
280 | static uint32_t acpi_pad_idle_cpus_num(void) | |
281 | { | |
282 | return ps_tsk_num; | |
283 | } | |
284 | ||
285 | static ssize_t acpi_pad_rrtime_store(struct device *dev, | |
286 | struct device_attribute *attr, const char *buf, size_t count) | |
287 | { | |
288 | unsigned long num; | |
289 | if (strict_strtoul(buf, 0, &num)) | |
290 | return -EINVAL; | |
291 | if (num < 1 || num >= 100) | |
292 | return -EINVAL; | |
293 | mutex_lock(&isolated_cpus_lock); | |
294 | round_robin_time = num; | |
295 | mutex_unlock(&isolated_cpus_lock); | |
296 | return count; | |
297 | } | |
298 | ||
299 | static ssize_t acpi_pad_rrtime_show(struct device *dev, | |
300 | struct device_attribute *attr, char *buf) | |
301 | { | |
32297abd | 302 | return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time); |
8e0af514 SL |
303 | } |
304 | static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR, | |
305 | acpi_pad_rrtime_show, | |
306 | acpi_pad_rrtime_store); | |
307 | ||
308 | static ssize_t acpi_pad_idlepct_store(struct device *dev, | |
309 | struct device_attribute *attr, const char *buf, size_t count) | |
310 | { | |
311 | unsigned long num; | |
312 | if (strict_strtoul(buf, 0, &num)) | |
313 | return -EINVAL; | |
314 | if (num < 1 || num >= 100) | |
315 | return -EINVAL; | |
316 | mutex_lock(&isolated_cpus_lock); | |
317 | idle_pct = num; | |
318 | mutex_unlock(&isolated_cpus_lock); | |
319 | return count; | |
320 | } | |
321 | ||
322 | static ssize_t acpi_pad_idlepct_show(struct device *dev, | |
323 | struct device_attribute *attr, char *buf) | |
324 | { | |
32297abd | 325 | return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct); |
8e0af514 SL |
326 | } |
327 | static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR, | |
328 | acpi_pad_idlepct_show, | |
329 | acpi_pad_idlepct_store); | |
330 | ||
331 | static ssize_t acpi_pad_idlecpus_store(struct device *dev, | |
332 | struct device_attribute *attr, const char *buf, size_t count) | |
333 | { | |
334 | unsigned long num; | |
335 | if (strict_strtoul(buf, 0, &num)) | |
336 | return -EINVAL; | |
337 | mutex_lock(&isolated_cpus_lock); | |
338 | acpi_pad_idle_cpus(num); | |
339 | mutex_unlock(&isolated_cpus_lock); | |
340 | return count; | |
341 | } | |
342 | ||
343 | static ssize_t acpi_pad_idlecpus_show(struct device *dev, | |
344 | struct device_attribute *attr, char *buf) | |
345 | { | |
32297abd NC |
346 | int n = 0; |
347 | n = cpumask_scnprintf(buf, PAGE_SIZE-2, to_cpumask(pad_busy_cpus_bits)); | |
348 | buf[n++] = '\n'; | |
349 | buf[n] = '\0'; | |
350 | return n; | |
8e0af514 SL |
351 | } |
352 | static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR, | |
353 | acpi_pad_idlecpus_show, | |
354 | acpi_pad_idlecpus_store); | |
355 | ||
356 | static int acpi_pad_add_sysfs(struct acpi_device *device) | |
357 | { | |
358 | int result; | |
359 | ||
360 | result = device_create_file(&device->dev, &dev_attr_idlecpus); | |
361 | if (result) | |
362 | return -ENODEV; | |
363 | result = device_create_file(&device->dev, &dev_attr_idlepct); | |
364 | if (result) { | |
365 | device_remove_file(&device->dev, &dev_attr_idlecpus); | |
366 | return -ENODEV; | |
367 | } | |
368 | result = device_create_file(&device->dev, &dev_attr_rrtime); | |
369 | if (result) { | |
370 | device_remove_file(&device->dev, &dev_attr_idlecpus); | |
371 | device_remove_file(&device->dev, &dev_attr_idlepct); | |
372 | return -ENODEV; | |
373 | } | |
374 | return 0; | |
375 | } | |
376 | ||
377 | static void acpi_pad_remove_sysfs(struct acpi_device *device) | |
378 | { | |
379 | device_remove_file(&device->dev, &dev_attr_idlecpus); | |
380 | device_remove_file(&device->dev, &dev_attr_idlepct); | |
381 | device_remove_file(&device->dev, &dev_attr_rrtime); | |
382 | } | |
383 | ||
c9ad8e06 LB |
384 | /* |
385 | * Query firmware how many CPUs should be idle | |
386 | * return -1 on failure | |
387 | */ | |
388 | static int acpi_pad_pur(acpi_handle handle) | |
8e0af514 SL |
389 | { |
390 | struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL}; | |
8e0af514 | 391 | union acpi_object *package; |
c9ad8e06 | 392 | int num = -1; |
8e0af514 | 393 | |
3b8cb427 | 394 | if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer))) |
c9ad8e06 | 395 | return num; |
3b8cb427 CG |
396 | |
397 | if (!buffer.length || !buffer.pointer) | |
c9ad8e06 | 398 | return num; |
3b8cb427 | 399 | |
8e0af514 | 400 | package = buffer.pointer; |
c9ad8e06 LB |
401 | |
402 | if (package->type == ACPI_TYPE_PACKAGE && | |
403 | package->package.count == 2 && | |
404 | package->package.elements[0].integer.value == 1) /* rev 1 */ | |
405 | ||
406 | num = package->package.elements[1].integer.value; | |
407 | ||
8e0af514 | 408 | kfree(buffer.pointer); |
c9ad8e06 | 409 | return num; |
8e0af514 SL |
410 | } |
411 | ||
412 | /* Notify firmware how many CPUs are idle */ | |
413 | static void acpi_pad_ost(acpi_handle handle, int stat, | |
414 | uint32_t idle_cpus) | |
415 | { | |
416 | union acpi_object params[3] = { | |
417 | {.type = ACPI_TYPE_INTEGER,}, | |
418 | {.type = ACPI_TYPE_INTEGER,}, | |
419 | {.type = ACPI_TYPE_BUFFER,}, | |
420 | }; | |
421 | struct acpi_object_list arg_list = {3, params}; | |
422 | ||
423 | params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY; | |
424 | params[1].integer.value = stat; | |
425 | params[2].buffer.length = 4; | |
426 | params[2].buffer.pointer = (void *)&idle_cpus; | |
427 | acpi_evaluate_object(handle, "_OST", &arg_list, NULL); | |
428 | } | |
429 | ||
430 | static void acpi_pad_handle_notify(acpi_handle handle) | |
431 | { | |
3b8cb427 | 432 | int num_cpus; |
8e0af514 SL |
433 | uint32_t idle_cpus; |
434 | ||
435 | mutex_lock(&isolated_cpus_lock); | |
c9ad8e06 LB |
436 | num_cpus = acpi_pad_pur(handle); |
437 | if (num_cpus < 0) { | |
8e0af514 SL |
438 | mutex_unlock(&isolated_cpus_lock); |
439 | return; | |
440 | } | |
3b8cb427 | 441 | acpi_pad_idle_cpus(num_cpus); |
8e0af514 | 442 | idle_cpus = acpi_pad_idle_cpus_num(); |
3b8cb427 | 443 | acpi_pad_ost(handle, 0, idle_cpus); |
8e0af514 SL |
444 | mutex_unlock(&isolated_cpus_lock); |
445 | } | |
446 | ||
447 | static void acpi_pad_notify(acpi_handle handle, u32 event, | |
448 | void *data) | |
449 | { | |
450 | struct acpi_device *device = data; | |
451 | ||
452 | switch (event) { | |
453 | case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: | |
454 | acpi_pad_handle_notify(handle); | |
455 | acpi_bus_generate_proc_event(device, event, 0); | |
456 | acpi_bus_generate_netlink_event(device->pnp.device_class, | |
457 | dev_name(&device->dev), event, 0); | |
458 | break; | |
459 | default: | |
cdf2a4ee | 460 | printk(KERN_WARNING "Unsupported event [0x%x]\n", event); |
8e0af514 SL |
461 | break; |
462 | } | |
463 | } | |
464 | ||
465 | static int acpi_pad_add(struct acpi_device *device) | |
466 | { | |
467 | acpi_status status; | |
468 | ||
469 | strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); | |
470 | strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); | |
471 | ||
472 | if (acpi_pad_add_sysfs(device)) | |
473 | return -ENODEV; | |
474 | ||
475 | status = acpi_install_notify_handler(device->handle, | |
476 | ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); | |
477 | if (ACPI_FAILURE(status)) { | |
478 | acpi_pad_remove_sysfs(device); | |
479 | return -ENODEV; | |
480 | } | |
481 | ||
482 | return 0; | |
483 | } | |
484 | ||
485 | static int acpi_pad_remove(struct acpi_device *device, | |
486 | int type) | |
487 | { | |
488 | mutex_lock(&isolated_cpus_lock); | |
489 | acpi_pad_idle_cpus(0); | |
490 | mutex_unlock(&isolated_cpus_lock); | |
491 | ||
492 | acpi_remove_notify_handler(device->handle, | |
493 | ACPI_DEVICE_NOTIFY, acpi_pad_notify); | |
494 | acpi_pad_remove_sysfs(device); | |
495 | return 0; | |
496 | } | |
497 | ||
498 | static const struct acpi_device_id pad_device_ids[] = { | |
499 | {"ACPI000C", 0}, | |
500 | {"", 0}, | |
501 | }; | |
502 | MODULE_DEVICE_TABLE(acpi, pad_device_ids); | |
503 | ||
504 | static struct acpi_driver acpi_pad_driver = { | |
505 | .name = "processor_aggregator", | |
506 | .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, | |
507 | .ids = pad_device_ids, | |
508 | .ops = { | |
509 | .add = acpi_pad_add, | |
510 | .remove = acpi_pad_remove, | |
511 | }, | |
512 | }; | |
513 | ||
514 | static int __init acpi_pad_init(void) | |
515 | { | |
516 | power_saving_mwait_init(); | |
517 | if (power_saving_mwait_eax == 0) | |
518 | return -EINVAL; | |
519 | ||
520 | return acpi_bus_register_driver(&acpi_pad_driver); | |
521 | } | |
522 | ||
523 | static void __exit acpi_pad_exit(void) | |
524 | { | |
525 | acpi_bus_unregister_driver(&acpi_pad_driver); | |
526 | } | |
527 | ||
528 | module_init(acpi_pad_init); | |
529 | module_exit(acpi_pad_exit); | |
530 | MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>"); | |
531 | MODULE_DESCRIPTION("ACPI Processor Aggregator Driver"); | |
532 | MODULE_LICENSE("GPL"); |