blob: 16fa979f7180b935a52fbfa03c75ca173359031d [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 *
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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090030#include <linux/slab.h>
Shaohua Li8e0af512009-07-27 18:11:02 -040031#include <acpi/acpi_bus.h>
32#include <acpi/acpi_drivers.h>
H. Peter Anvinbc83ccc2010-09-17 15:36:40 -070033#include <asm/mwait.h>
Shaohua Li8e0af512009-07-27 18:11:02 -040034
Dan Carpentera40770a2010-04-27 14:06:05 -070035#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
Shaohua Li8e0af512009-07-27 18:11:02 -040036#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
37#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
38static DEFINE_MUTEX(isolated_cpus_lock);
Stuart Hayes5f160122012-06-13 16:10:45 -050039static DEFINE_MUTEX(round_robin_lock);
Shaohua Li8e0af512009-07-27 18:11:02 -040040
Shaohua Li8e0af512009-07-27 18:11:02 -040041static unsigned long power_saving_mwait_eax;
Venkatesh Pallipadi0dc698b2010-05-18 14:39:16 -070042
43static unsigned char tsc_detected_unstable;
44static unsigned char tsc_marked_unstable;
Chen Gong8aa4b142010-05-30 11:37:08 +080045static unsigned char lapic_detected_unstable;
46static unsigned char lapic_marked_unstable;
Venkatesh Pallipadi0dc698b2010-05-18 14:39:16 -070047
Shaohua Li8e0af512009-07-27 18:11:02 -040048static 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
John Stultz592913e2010-07-13 17:56:20 -070076#if defined(CONFIG_X86)
Shaohua Li8e0af512009-07-27 18:11:02 -040077 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 */
Chen Gong8aa4b142010-05-30 11:37:08 +080084 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;
Shaohua Li8e0af512009-07-27 18:11:02 -040089 default:
Chen Gong8aa4b142010-05-30 11:37:08 +080090 /* TSC & LAPIC could halt in idle */
Venkatesh Pallipadi0dc698b2010-05-18 14:39:16 -070091 tsc_detected_unstable = 1;
Chen Gong8aa4b142010-05-30 11:37:08 +080092 lapic_detected_unstable = 1;
Shaohua Li8e0af512009-07-27 18:11:02 -040093 }
94#endif
95}
96
97static unsigned long cpu_weight[NR_CPUS];
98static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
99static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
100static 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;
Andrew Mortonf67538f2009-11-13 19:55:30 -0800105 unsigned long min_weight = -1;
106 unsigned long uninitialized_var(preferred_cpu);
Shaohua Li8e0af512009-07-27 18:11:02 -0400107
108 if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
109 return;
110
Stuart Hayes5f160122012-06-13 16:10:45 -0500111 mutex_lock(&round_robin_lock);
Shaohua Li8e0af512009-07-27 18:11:02 -0400112 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)) {
Stuart Hayes5f160122012-06-13 16:10:45 -0500120 mutex_unlock(&round_robin_lock);
Shaohua Li8e0af512009-07-27 18:11:02 -0400121 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]++;
Stuart Hayes5f160122012-06-13 16:10:45 -0500135 mutex_unlock(&round_robin_lock);
Shaohua Li8e0af512009-07-27 18:11:02 -0400136
137 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
138}
139
140static 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
147static unsigned int idle_pct = 5; /* percentage */
Len Brownfa7584e2012-06-13 22:12:51 -0400148static unsigned int round_robin_time = 1; /* second */
Shaohua Li8e0af512009-07-27 18:11:02 -0400149static 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, &param);
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
Shaohua Li8e0af512009-07-27 18:11:02 -0400172 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
173
174 while (!need_resched()) {
Venkatesh Pallipadi0dc698b2010-05-18 14:39:16 -0700175 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 }
Chen Gong8aa4b142010-05-30 11:37:08 +0800180 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 }
Shaohua Li8e0af512009-07-27 18:11:02 -0400189 local_irq_disable();
190 cpu = smp_processor_id();
Chen Gong8aa4b142010-05-30 11:37:08 +0800191 if (lapic_marked_unstable)
192 clockevents_notify(
193 CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
Shaohua Li8e0af512009-07-27 18:11:02 -0400194 stop_critical_timings();
195
196 __monitor((void *)&current_thread_info()->flags, 0, 0);
197 smp_mb();
198 if (!need_resched())
199 __mwait(power_saving_mwait_eax, 1);
200
201 start_critical_timings();
Chen Gong8aa4b142010-05-30 11:37:08 +0800202 if (lapic_marked_unstable)
203 clockevents_notify(
204 CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
Shaohua Li8e0af512009-07-27 18:11:02 -0400205 local_irq_enable();
206
207 if (jiffies > expire_time) {
208 do_sleep = 1;
209 break;
210 }
211 }
212
Shaohua Li8e0af512009-07-27 18:11:02 -0400213 /*
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%
Chen Gong3b8cb422009-12-14 09:42:28 +0800220 * CPU time. To make 'avoid starvation' work, takes a nap here.
Shaohua Li8e0af512009-07-27 18:11:02 -0400221 */
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
230static struct task_struct *ps_tsks[NR_CPUS];
231static unsigned int ps_tsk_num;
232static int create_power_saving_task(void)
233{
Chen Gong3b8cb422009-12-14 09:42:28 +0800234 int rc = -ENOMEM;
235
Shaohua Li8e0af512009-07-27 18:11:02 -0400236 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
237 (void *)(unsigned long)ps_tsk_num,
Len Brown150ed862012-06-13 22:07:20 -0400238 "acpi_pad/%d", ps_tsk_num);
Chen Gong3b8cb422009-12-14 09:42:28 +0800239 rc = IS_ERR(ps_tsks[ps_tsk_num]) ? PTR_ERR(ps_tsks[ps_tsk_num]) : 0;
240 if (!rc)
Shaohua Li8e0af512009-07-27 18:11:02 -0400241 ps_tsk_num++;
Chen Gong3b8cb422009-12-14 09:42:28 +0800242 else
243 ps_tsks[ps_tsk_num] = NULL;
244
245 return rc;
Shaohua Li8e0af512009-07-27 18:11:02 -0400246}
247
248static 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]);
Chen Gong3b8cb422009-12-14 09:42:28 +0800253 ps_tsks[ps_tsk_num] = NULL;
Shaohua Li8e0af512009-07-27 18:11:02 -0400254 }
255}
256
257static 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
Chen Gong3b8cb422009-12-14 09:42:28 +0800270static void acpi_pad_idle_cpus(unsigned int num_cpus)
Shaohua Li8e0af512009-07-27 18:11:02 -0400271{
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();
Shaohua Li8e0af512009-07-27 18:11:02 -0400278}
279
280static uint32_t acpi_pad_idle_cpus_num(void)
281{
282 return ps_tsk_num;
283}
284
285static 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;
Josh73d45112012-10-23 01:30:40 +0200289 if (kstrtoul(buf, 0, &num))
Shaohua Li8e0af512009-07-27 18:11:02 -0400290 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
299static ssize_t acpi_pad_rrtime_show(struct device *dev,
300 struct device_attribute *attr, char *buf)
301{
Naga Chumbalkar32297ab2011-02-02 23:26:58 +0000302 return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time);
Shaohua Li8e0af512009-07-27 18:11:02 -0400303}
304static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
305 acpi_pad_rrtime_show,
306 acpi_pad_rrtime_store);
307
308static 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;
Josh73d45112012-10-23 01:30:40 +0200312 if (kstrtoul(buf, 0, &num))
Shaohua Li8e0af512009-07-27 18:11:02 -0400313 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
322static ssize_t acpi_pad_idlepct_show(struct device *dev,
323 struct device_attribute *attr, char *buf)
324{
Naga Chumbalkar32297ab2011-02-02 23:26:58 +0000325 return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct);
Shaohua Li8e0af512009-07-27 18:11:02 -0400326}
327static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
328 acpi_pad_idlepct_show,
329 acpi_pad_idlepct_store);
330
331static 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;
Josh73d45112012-10-23 01:30:40 +0200335 if (kstrtoul(buf, 0, &num))
Shaohua Li8e0af512009-07-27 18:11:02 -0400336 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
343static ssize_t acpi_pad_idlecpus_show(struct device *dev,
344 struct device_attribute *attr, char *buf)
345{
Naga Chumbalkar32297ab2011-02-02 23:26:58 +0000346 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;
Shaohua Li8e0af512009-07-27 18:11:02 -0400351}
352static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
353 acpi_pad_idlecpus_show,
354 acpi_pad_idlecpus_store);
355
356static 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
377static 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
Len Brownc9ad8e02010-09-28 16:50:50 -0400384/*
385 * Query firmware how many CPUs should be idle
386 * return -1 on failure
387 */
388static int acpi_pad_pur(acpi_handle handle)
Shaohua Li8e0af512009-07-27 18:11:02 -0400389{
390 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
Shaohua Li8e0af512009-07-27 18:11:02 -0400391 union acpi_object *package;
Len Brownc9ad8e02010-09-28 16:50:50 -0400392 int num = -1;
Shaohua Li8e0af512009-07-27 18:11:02 -0400393
Chen Gong3b8cb422009-12-14 09:42:28 +0800394 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
Len Brownc9ad8e02010-09-28 16:50:50 -0400395 return num;
Chen Gong3b8cb422009-12-14 09:42:28 +0800396
397 if (!buffer.length || !buffer.pointer)
Len Brownc9ad8e02010-09-28 16:50:50 -0400398 return num;
Chen Gong3b8cb422009-12-14 09:42:28 +0800399
Shaohua Li8e0af512009-07-27 18:11:02 -0400400 package = buffer.pointer;
Len Brownc9ad8e02010-09-28 16:50:50 -0400401
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
Shaohua Li8e0af512009-07-27 18:11:02 -0400408 kfree(buffer.pointer);
Len Brownc9ad8e02010-09-28 16:50:50 -0400409 return num;
Shaohua Li8e0af512009-07-27 18:11:02 -0400410}
411
412/* Notify firmware how many CPUs are idle */
413static 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
430static void acpi_pad_handle_notify(acpi_handle handle)
431{
Chen Gong3b8cb422009-12-14 09:42:28 +0800432 int num_cpus;
Shaohua Li8e0af512009-07-27 18:11:02 -0400433 uint32_t idle_cpus;
434
435 mutex_lock(&isolated_cpus_lock);
Len Brownc9ad8e02010-09-28 16:50:50 -0400436 num_cpus = acpi_pad_pur(handle);
437 if (num_cpus < 0) {
Shaohua Li8e0af512009-07-27 18:11:02 -0400438 mutex_unlock(&isolated_cpus_lock);
439 return;
440 }
Chen Gong3b8cb422009-12-14 09:42:28 +0800441 acpi_pad_idle_cpus(num_cpus);
Shaohua Li8e0af512009-07-27 18:11:02 -0400442 idle_cpus = acpi_pad_idle_cpus_num();
Chen Gong3b8cb422009-12-14 09:42:28 +0800443 acpi_pad_ost(handle, 0, idle_cpus);
Shaohua Li8e0af512009-07-27 18:11:02 -0400444 mutex_unlock(&isolated_cpus_lock);
445}
446
447static 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:
Josh73d45112012-10-23 01:30:40 +0200460 pr_warn("Unsupported event [0x%x]\n", event);
Shaohua Li8e0af512009-07-27 18:11:02 -0400461 break;
462 }
463}
464
465static 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
485static 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
498static const struct acpi_device_id pad_device_ids[] = {
499 {"ACPI000C", 0},
500 {"", 0},
501};
502MODULE_DEVICE_TABLE(acpi, pad_device_ids);
503
504static 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
514static 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
523static void __exit acpi_pad_exit(void)
524{
525 acpi_bus_unregister_driver(&acpi_pad_driver);
526}
527
528module_init(acpi_pad_init);
529module_exit(acpi_pad_exit);
530MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
531MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
532MODULE_LICENSE("GPL");