blob: 8ea8211b2d589c6618d5037e40d653a3771edc55 [file] [log] [blame]
Shaohua Li8e0af512009-07-27 18:11:02 -04001/*
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 *
Shaohua Li8e0af512009-07-27 18:11:02 -040015 */
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>
Thomas Gleixner979081e2015-04-03 02:01:49 +020025#include <linux/tick.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090026#include <linux/slab.h>
Lv Zheng8b484632013-12-03 08:49:16 +080027#include <linux/acpi.h>
H. Peter Anvinbc83ccc2010-09-17 15:36:40 -070028#include <asm/mwait.h>
Shaohua Li8e0af512009-07-27 18:11:02 -040029
Dan Carpentera40770a2010-04-27 14:06:05 -070030#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
Shaohua Li8e0af512009-07-27 18:11:02 -040031#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
32#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
33static DEFINE_MUTEX(isolated_cpus_lock);
Stuart Hayes5f160122012-06-13 16:10:45 -050034static DEFINE_MUTEX(round_robin_lock);
Shaohua Li8e0af512009-07-27 18:11:02 -040035
Shaohua Li8e0af512009-07-27 18:11:02 -040036static unsigned long power_saving_mwait_eax;
Venkatesh Pallipadi0dc698b2010-05-18 14:39:16 -070037
38static unsigned char tsc_detected_unstable;
39static unsigned char tsc_marked_unstable;
40
Shaohua Li8e0af512009-07-27 18:11:02 -040041static 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
John Stultz592913e2010-07-13 17:56:20 -070069#if defined(CONFIG_X86)
Shaohua Li8e0af512009-07-27 18:11:02 -040070 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 */
Chen Gong8aa4b142010-05-30 11:37:08 +080077 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
78 tsc_detected_unstable = 1;
Chen Gong8aa4b142010-05-30 11:37:08 +080079 break;
Shaohua Li8e0af512009-07-27 18:11:02 -040080 default:
Thomas Gleixner3ff70552015-04-03 01:46:34 +020081 /* TSC could halt in idle */
Venkatesh Pallipadi0dc698b2010-05-18 14:39:16 -070082 tsc_detected_unstable = 1;
Shaohua Li8e0af512009-07-27 18:11:02 -040083 }
84#endif
85}
86
87static unsigned long cpu_weight[NR_CPUS];
88static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
89static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
90static 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;
Andrew Mortonf67538f2009-11-13 19:55:30 -080095 unsigned long min_weight = -1;
96 unsigned long uninitialized_var(preferred_cpu);
Shaohua Li8e0af512009-07-27 18:11:02 -040097
98 if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
99 return;
100
Stuart Hayes5f160122012-06-13 16:10:45 -0500101 mutex_lock(&round_robin_lock);
Shaohua Li8e0af512009-07-27 18:11:02 -0400102 cpumask_clear(tmp);
103 for_each_cpu(cpu, pad_busy_cpus)
Bartosz Golaszewski06931e62015-05-26 15:11:28 +0200104 cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu));
Shaohua Li8e0af512009-07-27 18:11:02 -0400105 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)) {
Stuart Hayes5f160122012-06-13 16:10:45 -0500110 mutex_unlock(&round_robin_lock);
Shaohua Li8e0af512009-07-27 18:11:02 -0400111 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]++;
Stuart Hayes5f160122012-06-13 16:10:45 -0500125 mutex_unlock(&round_robin_lock);
Shaohua Li8e0af512009-07-27 18:11:02 -0400126
127 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
128}
129
130static 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
137static unsigned int idle_pct = 5; /* percentage */
Len Brownfa7584e2012-06-13 22:12:51 -0400138static unsigned int round_robin_time = 1; /* second */
Shaohua Li8e0af512009-07-27 18:11:02 -0400139static 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, &param);
147
148 while (!kthread_should_stop()) {
Manuel Schölling4ff248f2014-05-22 22:56:36 +0200149 unsigned long expire_time;
Shaohua Li8e0af512009-07-27 18:11:02 -0400150
Shaohua Li8e0af512009-07-27 18:11:02 -0400151 /* round robin to cpus */
Manuel Schölling4ff248f2014-05-22 22:56:36 +0200152 expire_time = last_jiffies + round_robin_time * HZ;
153 if (time_before(expire_time, jiffies)) {
Shaohua Li8e0af512009-07-27 18:11:02 -0400154 last_jiffies = jiffies;
155 round_robin_cpu(tsk_index);
156 }
157
158 do_sleep = 0;
159
Shaohua Li8e0af512009-07-27 18:11:02 -0400160 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
161
162 while (!need_resched()) {
Venkatesh Pallipadi0dc698b2010-05-18 14:39:16 -0700163 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 }
Shaohua Li8e0af512009-07-27 18:11:02 -0400168 local_irq_disable();
Thomas Gleixner979081e2015-04-03 02:01:49 +0200169 tick_broadcast_enable();
Thomas Gleixnerc7952132015-04-03 02:06:37 +0200170 tick_broadcast_enter();
Shaohua Li8e0af512009-07-27 18:11:02 -0400171 stop_critical_timings();
172
Peter Zijlstra16824252013-12-12 15:08:36 +0100173 mwait_idle_with_hints(power_saving_mwait_eax, 1);
Shaohua Li8e0af512009-07-27 18:11:02 -0400174
175 start_critical_timings();
Thomas Gleixnerc7952132015-04-03 02:06:37 +0200176 tick_broadcast_exit();
Shaohua Li8e0af512009-07-27 18:11:02 -0400177 local_irq_enable();
178
Manuel Schölling4ff248f2014-05-22 22:56:36 +0200179 if (time_before(expire_time, jiffies)) {
Shaohua Li8e0af512009-07-27 18:11:02 -0400180 do_sleep = 1;
181 break;
182 }
183 }
184
Shaohua Li8e0af512009-07-27 18:11:02 -0400185 /*
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%
Chen Gong3b8cb422009-12-14 09:42:28 +0800192 * CPU time. To make 'avoid starvation' work, takes a nap here.
Shaohua Li8e0af512009-07-27 18:11:02 -0400193 */
Tony Camuso5b59c692014-04-25 14:19:29 -0400194 if (unlikely(do_sleep))
Shaohua Li8e0af512009-07-27 18:11:02 -0400195 schedule_timeout_killable(HZ * idle_pct / 100);
Tony Camuso5b59c692014-04-25 14:19:29 -0400196
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();
Shaohua Li8e0af512009-07-27 18:11:02 -0400203 }
204
205 exit_round_robin(tsk_index);
206 return 0;
207}
208
209static struct task_struct *ps_tsks[NR_CPUS];
210static unsigned int ps_tsk_num;
211static int create_power_saving_task(void)
212{
Rusty Russell5d7e4382013-07-15 11:22:32 +0930213 int rc;
Chen Gong3b8cb422009-12-14 09:42:28 +0800214
Shaohua Li8e0af512009-07-27 18:11:02 -0400215 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
216 (void *)(unsigned long)ps_tsk_num,
Len Brown150ed862012-06-13 22:07:20 -0400217 "acpi_pad/%d", ps_tsk_num);
Rusty Russell5d7e4382013-07-15 11:22:32 +0930218
219 if (IS_ERR(ps_tsks[ps_tsk_num])) {
220 rc = PTR_ERR(ps_tsks[ps_tsk_num]);
Chen Gong3b8cb422009-12-14 09:42:28 +0800221 ps_tsks[ps_tsk_num] = NULL;
Rusty Russell5d7e4382013-07-15 11:22:32 +0930222 } else {
223 rc = 0;
224 ps_tsk_num++;
225 }
Chen Gong3b8cb422009-12-14 09:42:28 +0800226
227 return rc;
Shaohua Li8e0af512009-07-27 18:11:02 -0400228}
229
230static 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]);
Chen Gong3b8cb422009-12-14 09:42:28 +0800235 ps_tsks[ps_tsk_num] = NULL;
Shaohua Li8e0af512009-07-27 18:11:02 -0400236 }
237}
238
239static 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
Chen Gong3b8cb422009-12-14 09:42:28 +0800252static void acpi_pad_idle_cpus(unsigned int num_cpus)
Shaohua Li8e0af512009-07-27 18:11:02 -0400253{
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();
Shaohua Li8e0af512009-07-27 18:11:02 -0400260}
261
262static uint32_t acpi_pad_idle_cpus_num(void)
263{
264 return ps_tsk_num;
265}
266
267static 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;
Josh73d45112012-10-23 01:30:40 +0200271 if (kstrtoul(buf, 0, &num))
Shaohua Li8e0af512009-07-27 18:11:02 -0400272 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
281static ssize_t acpi_pad_rrtime_show(struct device *dev,
282 struct device_attribute *attr, char *buf)
283{
Naga Chumbalkar32297ab2011-02-02 23:26:58 +0000284 return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time);
Shaohua Li8e0af512009-07-27 18:11:02 -0400285}
286static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
287 acpi_pad_rrtime_show,
288 acpi_pad_rrtime_store);
289
290static 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;
Josh73d45112012-10-23 01:30:40 +0200294 if (kstrtoul(buf, 0, &num))
Shaohua Li8e0af512009-07-27 18:11:02 -0400295 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
304static ssize_t acpi_pad_idlepct_show(struct device *dev,
305 struct device_attribute *attr, char *buf)
306{
Naga Chumbalkar32297ab2011-02-02 23:26:58 +0000307 return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct);
Shaohua Li8e0af512009-07-27 18:11:02 -0400308}
309static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
310 acpi_pad_idlepct_show,
311 acpi_pad_idlepct_store);
312
313static 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;
Josh73d45112012-10-23 01:30:40 +0200317 if (kstrtoul(buf, 0, &num))
Shaohua Li8e0af512009-07-27 18:11:02 -0400318 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
325static ssize_t acpi_pad_idlecpus_show(struct device *dev,
326 struct device_attribute *attr, char *buf)
327{
Sudeep Holla5aaba362014-09-30 14:48:22 +0100328 return cpumap_print_to_pagebuf(false, buf,
329 to_cpumask(pad_busy_cpus_bits));
Shaohua Li8e0af512009-07-27 18:11:02 -0400330}
Sudeep Holla5aaba362014-09-30 14:48:22 +0100331
Shaohua Li8e0af512009-07-27 18:11:02 -0400332static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
333 acpi_pad_idlecpus_show,
334 acpi_pad_idlecpus_store);
335
336static 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
357static 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
Len Brownc9ad8e02010-09-28 16:50:50 -0400364/*
365 * Query firmware how many CPUs should be idle
366 * return -1 on failure
367 */
368static int acpi_pad_pur(acpi_handle handle)
Shaohua Li8e0af512009-07-27 18:11:02 -0400369{
370 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
Shaohua Li8e0af512009-07-27 18:11:02 -0400371 union acpi_object *package;
Len Brownc9ad8e02010-09-28 16:50:50 -0400372 int num = -1;
Shaohua Li8e0af512009-07-27 18:11:02 -0400373
Chen Gong3b8cb422009-12-14 09:42:28 +0800374 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
Len Brownc9ad8e02010-09-28 16:50:50 -0400375 return num;
Chen Gong3b8cb422009-12-14 09:42:28 +0800376
377 if (!buffer.length || !buffer.pointer)
Len Brownc9ad8e02010-09-28 16:50:50 -0400378 return num;
Chen Gong3b8cb422009-12-14 09:42:28 +0800379
Shaohua Li8e0af512009-07-27 18:11:02 -0400380 package = buffer.pointer;
Len Brownc9ad8e02010-09-28 16:50:50 -0400381
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
Shaohua Li8e0af512009-07-27 18:11:02 -0400388 kfree(buffer.pointer);
Len Brownc9ad8e02010-09-28 16:50:50 -0400389 return num;
Shaohua Li8e0af512009-07-27 18:11:02 -0400390}
391
Shaohua Li8e0af512009-07-27 18:11:02 -0400392static void acpi_pad_handle_notify(acpi_handle handle)
393{
Chen Gong3b8cb422009-12-14 09:42:28 +0800394 int num_cpus;
Shaohua Li8e0af512009-07-27 18:11:02 -0400395 uint32_t idle_cpus;
Jiang Liu8b296d92014-02-19 14:02:16 +0800396 struct acpi_buffer param = {
397 .length = 4,
398 .pointer = (void *)&idle_cpus,
399 };
Shaohua Li8e0af512009-07-27 18:11:02 -0400400
401 mutex_lock(&isolated_cpus_lock);
Len Brownc9ad8e02010-09-28 16:50:50 -0400402 num_cpus = acpi_pad_pur(handle);
403 if (num_cpus < 0) {
Shaohua Li8e0af512009-07-27 18:11:02 -0400404 mutex_unlock(&isolated_cpus_lock);
405 return;
406 }
Chen Gong3b8cb422009-12-14 09:42:28 +0800407 acpi_pad_idle_cpus(num_cpus);
Shaohua Li8e0af512009-07-27 18:11:02 -0400408 idle_cpus = acpi_pad_idle_cpus_num();
Jiang Liu8b296d92014-02-19 14:02:16 +0800409 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, &param);
Shaohua Li8e0af512009-07-27 18:11:02 -0400410 mutex_unlock(&isolated_cpus_lock);
411}
412
413static 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);
Shaohua Li8e0af512009-07-27 18:11:02 -0400421 acpi_bus_generate_netlink_event(device->pnp.device_class,
422 dev_name(&device->dev), event, 0);
423 break;
424 default:
Josh73d45112012-10-23 01:30:40 +0200425 pr_warn("Unsupported event [0x%x]\n", event);
Shaohua Li8e0af512009-07-27 18:11:02 -0400426 break;
427 }
428}
429
430static 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
Rafael J. Wysocki51fac832013-01-24 00:24:48 +0100450static int acpi_pad_remove(struct acpi_device *device)
Shaohua Li8e0af512009-07-27 18:11:02 -0400451{
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
462static const struct acpi_device_id pad_device_ids[] = {
463 {"ACPI000C", 0},
464 {"", 0},
465};
466MODULE_DEVICE_TABLE(acpi, pad_device_ids);
467
468static 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
478static 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
487static void __exit acpi_pad_exit(void)
488{
489 acpi_bus_unregister_driver(&acpi_pad_driver);
490}
491
492module_init(acpi_pad_init);
493module_exit(acpi_pad_exit);
494MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
495MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
496MODULE_LICENSE("GPL");