aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/cpufreq/intel_pstate.c
blob: badf6206b2b20d7284ffbbd098fd66676937fb64 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
/*
 * intel_pstate.c: Native P state management for Intel processors
 *
 * (C) Copyright 2012 Intel Corporation
 * Author: Dirk Brandewie <dirk.j.brandewie@intel.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; version 2
 * of the License.
 */

#include <linux/kernel.h>
#include <linux/kernel_stat.h>
#include <linux/module.h>
#include <linux/ktime.h>
#include <linux/hrtimer.h>
#include <linux/tick.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/sysfs.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <trace/events/power.h>

#include <asm/div64.h>
#include <asm/msr.h>
#include <asm/cpu_device_id.h>

#define SAMPLE_COUNT		3

#define FRAC_BITS 8
#define int_tofp(X) ((int64_t)(X) << FRAC_BITS)
#define fp_toint(X) ((X) >> FRAC_BITS)

static inline int32_t mul_fp(int32_t x, int32_t y)
{
	return ((int64_t)x * (int64_t)y) >> FRAC_BITS;
}

static inline int32_t div_fp(int32_t x, int32_t y)
{
	return div_s64((int64_t)x << FRAC_BITS, (int64_t)y);
}

struct sample {
	int core_pct_busy;
	u64 aperf;
	u64 mperf;
	int freq;
};

struct pstate_data {
	int	current_pstate;
	int	min_pstate;
	int	max_pstate;
	int	turbo_pstate;
};

struct _pid {
	int setpoint;
	int32_t integral;
	int32_t p_gain;
	int32_t i_gain;
	int32_t d_gain;
	int deadband;
	int last_err;
};

struct cpudata {
	int cpu;

	char name[64];

	struct timer_list timer;

	struct pstate_adjust_policy *pstate_policy;
	struct pstate_data pstate;
	struct _pid pid;

	int min_pstate_count;

	u64	prev_aperf;
	u64	prev_mperf;
	int	sample_ptr;
	struct sample samples[SAMPLE_COUNT];
};

static struct cpudata **all_cpu_data;
struct pstate_adjust_policy {
	int sample_rate_ms;
	int deadband;
	int setpoint;
	int p_gain_pct;
	int d_gain_pct;
	int i_gain_pct;
};

static struct pstate_adjust_policy default_policy = {
	.sample_rate_ms = 10,
	.deadband = 0,
	.setpoint = 97,
	.p_gain_pct = 20,
	.d_gain_pct = 0,
	.i_gain_pct = 0,
};

struct perf_limits {
	int no_turbo;
	int max_perf_pct;
	int min_perf_pct;
	int32_t max_perf;
	int32_t min_perf;
	int max_policy_pct;
	int max_sysfs_pct;
};

static struct perf_limits limits = {
	.no_turbo = 0,
	.max_perf_pct = 100,
	.max_perf = int_tofp(1),
	.min_perf_pct = 0,
	.min_perf = 0,
	.max_policy_pct = 100,
	.max_sysfs_pct = 100,
};

static inline void pid_reset(struct _pid *pid, int setpoint, int busy,
			int deadband, int integral) {
	pid->setpoint = setpoint;
	pid->deadband  = deadband;
	pid->integral  = int_tofp(integral);
	pid->last_err  = setpoint - busy;
}

static inline void pid_p_gain_set(struct _pid *pid, int percent)
{
	pid->p_gain = div_fp(int_tofp(percent), int_tofp(100));
}

static inline void pid_i_gain_set(struct _pid *pid, int percent)
{
	pid->i_gain = div_fp(int_tofp(percent), int_tofp(100));
}

static inline void pid_d_gain_set(struct _pid *pid, int percent)
{

	pid->d_gain = div_fp(int_tofp(percent), int_tofp(100));
}

static signed int pid_calc(struct _pid *pid, int busy)
{
	signed int err, result;
	int32_t pterm, dterm, fp_error;
	int32_t integral_limit;

	err = pid->setpoint - busy;
	fp_error = int_tofp(err);

	if (abs(err) <= pid->deadband)
		return 0;

	pterm = mul_fp(pid->p_gain, fp_error);

	pid->integral += fp_error;

	/* limit the integral term */
	integral_limit = int_tofp(30);
	if (pid->integral > integral_limit)
		pid->integral = integral_limit;
	if (pid->integral < -integral_limit)
		pid->integral = -integral_limit;

	dterm = mul_fp(pid->d_gain, (err - pid->last_err));
	pid->last_err = err;

	result = pterm + mul_fp(pid->integral, pid->i_gain) + dterm;

	return (signed int)fp_toint(result);
}

static inline void intel_pstate_busy_pid_reset(struct cpudata *cpu)
{
	pid_p_gain_set(&cpu->pid, cpu->pstate_policy->p_gain_pct);
	pid_d_gain_set(&cpu->pid, cpu->pstate_policy->d_gain_pct);
	pid_i_gain_set(&cpu->pid, cpu->pstate_policy->i_gain_pct);

	pid_reset(&cpu->pid,
		cpu->pstate_policy->setpoint,
		100,
		cpu->pstate_policy->deadband,
		0);
}

static inline void intel_pstate_reset_all_pid(void)
{
	unsigned int cpu;
	for_each_online_cpu(cpu) {
		if (all_cpu_data[cpu])
			intel_pstate_busy_pid_reset(all_cpu_data[cpu]);
	}
}

/************************** debugfs begin ************************/
static int pid_param_set(void *data, u64 val)
{
	*(u32 *)data = val;
	intel_pstate_reset_all_pid();
	return 0;
}
static int pid_param_get(void *data, u64 *val)
{
	*val = *(u32 *)data;
	return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_pid_param, pid_param_get,
			pid_param_set, "%llu\n");

struct pid_param {
	char *name;
	void *value;
};

static struct pid_param pid_files[] = {
	{"sample_rate_ms", &default_policy.sample_rate_ms},
	{"d_gain_pct", &default_policy.d_gain_pct},
	{"i_gain_pct", &default_policy.i_gain_pct},
	{"deadband", &default_policy.deadband},
	{"setpoint", &default_policy.setpoint},
	{"p_gain_pct", &default_policy.p_gain_pct},
	{NULL, NULL}
};

static struct dentry *debugfs_parent;
static void intel_pstate_debug_expose_params(void)
{
	int i = 0;

	debugfs_parent = debugfs_create_dir("pstate_snb", NULL);
	if (IS_ERR_OR_NULL(debugfs_parent))
		return;
	while (pid_files[i].name) {
		debugfs_create_file(pid_files[i].name, 0660,
				debugfs_parent, pid_files[i].value,
				&fops_pid_param);
		i++;
	}
}

/************************** debugfs end ************************/

/************************** sysfs begin ************************/
#define show_one(file_name, object)					\
	static ssize_t show_##file_name					\
	(struct kobject *kobj, struct attribute *attr, char *buf)	\
	{								\
		return sprintf(buf, "%u\n", limits.object);		\
	}

static ssize_t store_no_turbo(struct kobject *a, struct attribute *b,
				const char *buf, size_t count)
{
	unsigned int input;
	int ret;
	ret = sscanf(buf, "%u", &input);
	if (ret != 1)
		return -EINVAL;
	limits.no_turbo = clamp_t(int, input, 0 , 1);

	return count;
}

static ssize_t store_max_perf_pct(struct kobject *a, struct attribute *b,
				const char *buf, size_t count)
{
	unsigned int input;
	int ret;
	ret = sscanf(buf, "%u", &input);
	if (ret != 1)
		return -EINVAL;

	limits.max_sysfs_pct = clamp_t(int, input, 0 , 100);
	limits.max_perf_pct = min(limits.max_policy_pct, limits.max_sysfs_pct);
	limits.max_perf = div_fp(int_tofp(limits.max_perf_pct), int_tofp(100));
	return count;
}

static ssize_t store_min_perf_pct(struct kobject *a, struct attribute *b,
				const char *buf, size_t count)
{
	unsigned int input;
	int ret;
	ret = sscanf(buf, "%u", &input);
	if (ret != 1)
		return -EINVAL;
	limits.min_perf_pct = clamp_t(int, input, 0 , 100);
	limits.min_perf = div_fp(int_tofp(limits.min_perf_pct), int_tofp(100));

	return count;
}

show_one(no_turbo, no_turbo);
show_one(max_perf_pct, max_perf_pct);
show_one(min_perf_pct, min_perf_pct);

define_one_global_rw(no_turbo);
define_one_global_rw(max_perf_pct);
define_one_global_rw(min_perf_pct);

static struct attribute *intel_pstate_attributes[] = {
	&no_turbo.attr,
	&max_perf_pct.attr,
	&min_perf_pct.attr,
	NULL
};

static struct attribute_group intel_pstate_attr_group = {
	.attrs = intel_pstate_attributes,
};
static struct kobject *intel_pstate_kobject;

static void intel_pstate_sysfs_expose_params(void)
{
	int rc;

	intel_pstate_kobject = kobject_create_and_add("intel_pstate",
						&cpu_subsys.dev_root->kobj);
	BUG_ON(!intel_pstate_kobject);
	rc = sysfs_create_group(intel_pstate_kobject,
				&intel_pstate_attr_group);
	BUG_ON(rc);
}

/************************** sysfs end ************************/

static int intel_pstate_min_pstate(void)
{
	u64 value;
	rdmsrl(MSR_PLATFORM_INFO, value);
	return (value >> 40) & 0xFF;
}

static int intel_pstate_max_pstate(void)
{
	u64 value;
	rdmsrl(MSR_PLATFORM_INFO, value);
	return (value >> 8) & 0xFF;
}

static int intel_pstate_turbo_pstate(void)
{
	u64 value;
	int nont, ret;
	rdmsrl(MSR_NHM_TURBO_RATIO_LIMIT, value);
	nont = intel_pstate_max_pstate();
	ret = ((value) & 255);
	if (ret <= nont)
		ret = nont;
	return ret;
}

static void intel_pstate_get_min_max(struct cpudata *cpu, int *min, int *max)
{
	int max_perf = cpu->pstate.turbo_pstate;
	int min_perf;
	if (limits.no_turbo)
		max_perf = cpu->pstate.max_pstate;

	max_perf = fp_toint(mul_fp(int_tofp(max_perf), limits.max_perf));
	*max = clamp_t(int, max_perf,
			cpu->pstate.min_pstate, cpu->pstate.turbo_pstate);

	min_perf = fp_toint(mul_fp(int_tofp(max_perf), limits.min_perf));
	*min = clamp_t(int, min_perf,
			cpu->pstate.min_pstate, max_perf);
}

static void intel_pstate_set_pstate(struct cpudata *cpu, int pstate)
{
	int max_perf, min_perf;
	u64 val;

	intel_pstate_get_min_max(cpu, &min_perf, &max_perf);

	pstate = clamp_t(int, pstate, min_perf, max_perf);

	if (pstate == cpu->pstate.current_pstate)
		return;

	trace_cpu_frequency(pstate * 100000, cpu->cpu);

	cpu->pstate.current_pstate = pstate;
	val = pstate << 8;
	if (limits.no_turbo)
		val |= (u64)1 << 32;

	wrmsrl(MSR_IA32_PERF_CTL, val);
}

static inline void intel_pstate_pstate_increase(struct cpudata *cpu, int steps)
{
	int target;
	target = cpu->pstate.current_pstate + steps;

	intel_pstate_set_pstate(cpu, target);
}

static inline void intel_pstate_pstate_decrease(struct cpudata *cpu, int steps)
{
	int target;
	target = cpu->pstate.current_pstate - steps;
	intel_pstate_set_pstate(cpu, target);
}

static void intel_pstate_get_cpu_pstates(struct cpudata *cpu)
{
	sprintf(cpu->name, "Intel 2nd generation core");

	cpu->pstate.min_pstate = intel_pstate_min_pstate();
	cpu->pstate.max_pstate = intel_pstate_max_pstate();
	cpu->pstate.turbo_pstate = intel_pstate_turbo_pstate();

	/*
	 * goto max pstate so we don't slow up boot if we are built-in if we are
	 * a module we will take care of it during normal operation
	 */
	intel_pstate_set_pstate(cpu, cpu->pstate.max_pstate);
}

static inline void intel_pstate_calc_busy(struct cpudata *cpu,
					struct sample *sample)
{
	u64 core_pct;
	core_pct = div64_u64(sample->aperf * 100, sample->mperf);
	sample->freq = cpu->pstate.max_pstate * core_pct * 1000;

	sample->core_pct_busy = core_pct;
}

static inline void intel_pstate_sample(struct cpudata *cpu)
{
	u64 aperf, mperf;

	rdmsrl(MSR_IA32_APERF, aperf);
	rdmsrl(MSR_IA32_MPERF, mperf);
	cpu->sample_ptr = (cpu->sample_ptr + 1) % SAMPLE_COUNT;
	cpu->samples[cpu->sample_ptr].aperf = aperf;
	cpu->samples[cpu->sample_ptr].mperf = mperf;
	cpu->samples[cpu->sample_ptr].aperf -= cpu->prev_aperf;
	cpu->samples[cpu->sample_ptr].mperf -= cpu->prev_mperf;

	intel_pstate_calc_busy(cpu, &cpu->samples[cpu->sample_ptr]);

	cpu->prev_aperf = aperf;
	cpu->prev_mperf = mperf;
}

static inline void intel_pstate_set_sample_time(struct cpudata *cpu)
{
	int sample_time, delay;

	sample_time = cpu->pstate_policy->sample_rate_ms;
	delay = msecs_to_jiffies(sample_time);
	mod_timer_pinned(&cpu->timer, jiffies + delay);
}

static inline int intel_pstate_get_scaled_busy(struct cpudata *cpu)
{
	int32_t busy_scaled;
	int32_t core_busy, max_pstate, current_pstate;

	core_busy = int_tofp(cpu->samples[cpu->sample_ptr].core_pct_busy);
	max_pstate = int_tofp(cpu->pstate.max_pstate);
	current_pstate = int_tofp(cpu->pstate.current_pstate);
	busy_scaled = mul_fp(core_busy, div_fp(max_pstate, current_pstate));

	return fp_toint(busy_scaled);
}

static inline void intel_pstate_adjust_busy_pstate(struct cpudata *cpu)
{
	int busy_scaled;
	struct _pid *pid;
	signed int ctl = 0;
	int steps;

	pid = &cpu->pid;
	busy_scaled = intel_pstate_get_scaled_busy(cpu);

	ctl = pid_calc(pid, busy_scaled);

	steps = abs(ctl);
	if (ctl < 0)
		intel_pstate_pstate_increase(cpu, steps);
	else
		intel_pstate_pstate_decrease(cpu, steps);
}

static void intel_pstate_timer_func(unsigned long __data)
{
	struct cpudata *cpu = (struct cpudata *) __data;

	intel_pstate_sample(cpu);
	intel_pstate_adjust_busy_pstate(cpu);

	if (cpu->pstate.current_pstate == cpu->pstate.min_pstate) {
		cpu->min_pstate_count++;
		if (!(cpu->min_pstate_count % 5)) {
			intel_pstate_set_pstate(cpu, cpu->pstate.max_pstate);
		}
	} else
		cpu->min_pstate_count = 0;

	intel_pstate_set_sample_time(cpu);
}

#define ICPU(model, policy) \
	{ X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, (unsigned long)&policy }

static const struct x86_cpu_id intel_pstate_cpu_ids[] = {
	ICPU(0x2a, default_policy),
	ICPU(0x2d, default_policy),
	ICPU(0x3a, default_policy),
	ICPU(0x3c, default_policy),
	ICPU(0x3e, default_policy),
	ICPU(0x3f, default_policy),
	ICPU(0x45, default_policy),
	ICPU(0x46, default_policy),
	{}
};
MODULE_DEVICE_TABLE(x86cpu, intel_pstate_cpu_ids);

static int intel_pstate_init_cpu(unsigned int cpunum)
{

	const struct x86_cpu_id *id;
	struct cpudata *cpu;

	id = x86_match_cpu(intel_pstate_cpu_ids);
	if (!id)
		return -ENODEV;

	all_cpu_data[cpunum] = kzalloc(sizeof(struct cpudata), GFP_KERNEL);
	if (!all_cpu_data[cpunum])
		return -ENOMEM;

	cpu = all_cpu_data[cpunum];

	intel_pstate_get_cpu_pstates(cpu);

	cpu->cpu = cpunum;
	cpu->pstate_policy =
		(struct pstate_adjust_policy *)id->driver_data;
	init_timer_deferrable(&cpu->timer);
	cpu->timer.function = intel_pstate_timer_func;
	cpu->timer.data =
		(unsigned long)cpu;
	cpu->timer.expires = jiffies + HZ/100;
	intel_pstate_busy_pid_reset(cpu);
	intel_pstate_sample(cpu);
	intel_pstate_set_pstate(cpu, cpu->pstate.max_pstate);

	add_timer_on(&cpu->timer, cpunum);

	pr_info("Intel pstate controlling: cpu %d\n", cpunum);

	return 0;
}

static unsigned int intel_pstate_get(unsigned int cpu_num)
{
	struct sample *sample;
	struct cpudata *cpu;

	cpu = all_cpu_data[cpu_num];
	if (!cpu)
		return 0;
	sample = &cpu->samples[cpu->sample_ptr];
	return sample->freq;
}

static int intel_pstate_set_policy(struct cpufreq_policy *policy)
{
	struct cpudata *cpu;

	cpu = all_cpu_data[policy->cpu];

	if (!policy->cpuinfo.max_freq)
		return -ENODEV;

	if (policy->policy == CPUFREQ_POLICY_PERFORMANCE) {
		limits.min_perf_pct = 100;
		limits.min_perf = int_tofp(1);
		limits.max_perf_pct = 100;
		limits.max_perf = int_tofp(1);
		limits.no_turbo = 0;
		return 0;
	}
	limits.min_perf_pct = (policy->min * 100) / policy->cpuinfo.max_freq;
	limits.min_perf_pct = clamp_t(int, limits.min_perf_pct, 0 , 100);
	limits.min_perf = div_fp(int_tofp(limits.min_perf_pct), int_tofp(100));

	limits.max_policy_pct = policy->max * 100 / policy->cpuinfo.max_freq;
	limits.max_policy_pct = clamp_t(int, limits.max_policy_pct, 0 , 100);
	limits.max_perf_pct = min(limits.max_policy_pct, limits.max_sysfs_pct);
	limits.max_perf = div_fp(int_tofp(limits.max_perf_pct), int_tofp(100));

	return 0;
}

static int intel_pstate_verify_policy(struct cpufreq_policy *policy)
{
	cpufreq_verify_within_limits(policy,
				policy->cpuinfo.min_freq,
				policy->cpuinfo.max_freq);

	if ((policy->policy != CPUFREQ_POLICY_POWERSAVE) &&
		(policy->policy != CPUFREQ_POLICY_PERFORMANCE))
		return -EINVAL;

	return 0;
}

static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
{
	int cpu = policy->cpu;

	del_timer(&all_cpu_data[cpu]->timer);
	kfree(all_cpu_data[cpu]);
	all_cpu_data[cpu] = NULL;
	return 0;
}

static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
{
	struct cpudata *cpu;
	int rc;

	rc = intel_pstate_init_cpu(policy->cpu);
	if (rc)
		return rc;

	cpu = all_cpu_data[policy->cpu];

	if (!limits.no_turbo &&
		limits.min_perf_pct == 100 && limits.max_perf_pct == 100)
		policy->policy = CPUFREQ_POLICY_PERFORMANCE;
	else
		policy->policy = CPUFREQ_POLICY_POWERSAVE;

	policy->min = cpu->pstate.min_pstate * 100000;
	policy->max = cpu->pstate.turbo_pstate * 100000;

	/* cpuinfo and default policy values */
	policy->cpuinfo.min_freq = cpu->pstate.min_pstate * 100000;
	policy->cpuinfo.max_freq = cpu->pstate.turbo_pstate * 100000;
	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
	cpumask_set_cpu(policy->cpu, policy->cpus);

	return 0;
}

static struct cpufreq_driver intel_pstate_driver = {
	.flags		= CPUFREQ_CONST_LOOPS,
	.verify		= intel_pstate_verify_policy,
	.setpolicy	= intel_pstate_set_policy,
	.get		= intel_pstate_get,
	.init		= intel_pstate_cpu_init,
	.exit		= intel_pstate_cpu_exit,
	.name		= "intel_pstate",
};

static int __initdata no_load;

static int intel_pstate_msrs_not_valid(void)
{
	/* Check that all the msr's we are using are valid. */
	u64 aperf, mperf, tmp;

	rdmsrl(MSR_IA32_APERF, aperf);
	rdmsrl(MSR_IA32_MPERF, mperf);

	if (!intel_pstate_min_pstate() ||
		!intel_pstate_max_pstate() ||
		!intel_pstate_turbo_pstate())
		return -ENODEV;

	rdmsrl(MSR_IA32_APERF, tmp);
	if (!(tmp - aperf))
		return -ENODEV;

	rdmsrl(MSR_IA32_MPERF, tmp);
	if (!(tmp - mperf))
		return -ENODEV;

	return 0;
}
static int __init intel_pstate_init(void)
{
	int cpu, rc = 0;
	const struct x86_cpu_id *id;

	if (no_load)
		return -ENODEV;

	id = x86_match_cpu(intel_pstate_cpu_ids);
	if (!id)
		return -ENODEV;

	if (intel_pstate_msrs_not_valid())
		return -ENODEV;

	pr_info("Intel P-state driver initializing.\n");

	all_cpu_data = vzalloc(sizeof(void *) * num_possible_cpus());
	if (!all_cpu_data)
		return -ENOMEM;

	rc = cpufreq_register_driver(&intel_pstate_driver);
	if (rc)
		goto out;

	intel_pstate_debug_expose_params();
	intel_pstate_sysfs_expose_params();
	return rc;
out:
	get_online_cpus();
	for_each_online_cpu(cpu) {
		if (all_cpu_data[cpu]) {
			del_timer_sync(&all_cpu_data[cpu]->timer);
			kfree(all_cpu_data[cpu]);
		}
	}

	put_online_cpus();
	vfree(all_cpu_data);
	return -ENODEV;
}
device_initcall(intel_pstate_init);

static int __init intel_pstate_setup(char *str)
{
	if (!str)
		return -EINVAL;

	if (!strcmp(str, "disable"))
		no_load = 1;
	return 0;
}
early_param("intel_pstate", intel_pstate_setup);

MODULE_AUTHOR("Dirk Brandewie <dirk.j.brandewie@intel.com>");
MODULE_DESCRIPTION("'intel_pstate' - P state driver Intel Core processors");
MODULE_LICENSE("GPL");