summaryrefslogtreecommitdiff
path: root/drivers/char/i8k.c
blob: 18571b5d5c468422d90781a8bc1f2ac2e7e7bfc7 (plain)
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
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
/*
 * i8k.c -- Linux driver for accessing the SMM BIOS on Dell laptops.
 *
 * Copyright (C) 2001  Massimo Dal Zotto <dz@debian.org>
 *
 * Hwmon integration:
 * Copyright (C) 2011  Jean Delvare <khali@linux-fr.org>
 * Copyright (C) 2013  Guenter Roeck <linux@roeck-us.net>
 *
 * 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; either version 2, or (at your option) any
 * later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/dmi.h>
#include <linux/capability.h>
#include <linux/mutex.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/sched.h>

#include <linux/i8k.h>

#define I8K_SMM_FN_STATUS	0x0025
#define I8K_SMM_POWER_STATUS	0x0069
#define I8K_SMM_SET_FAN		0x01a3
#define I8K_SMM_GET_FAN		0x00a3
#define I8K_SMM_GET_SPEED	0x02a3
#define I8K_SMM_GET_TEMP	0x10a3
#define I8K_SMM_GET_DELL_SIG1	0xfea3
#define I8K_SMM_GET_DELL_SIG2	0xffa3
#define I8K_SMM_BIOS_VERSION	0x00a6

#define I8K_FAN_MULT		30
#define I8K_MAX_TEMP		127

#define I8K_FN_NONE		0x00
#define I8K_FN_UP		0x01
#define I8K_FN_DOWN		0x02
#define I8K_FN_MUTE		0x04
#define I8K_FN_MASK		0x07
#define I8K_FN_SHIFT		8

#define I8K_POWER_AC		0x05
#define I8K_POWER_BATTERY	0x01

#define I8K_TEMPERATURE_BUG	1

static DEFINE_MUTEX(i8k_mutex);
static char bios_version[4];
static struct device *i8k_hwmon_dev;
static u32 i8k_hwmon_flags;

#define I8K_HWMON_HAVE_TEMP1	(1 << 0)
#define I8K_HWMON_HAVE_TEMP2	(1 << 1)
#define I8K_HWMON_HAVE_TEMP3	(1 << 2)
#define I8K_HWMON_HAVE_TEMP4	(1 << 3)
#define I8K_HWMON_HAVE_FAN1	(1 << 4)
#define I8K_HWMON_HAVE_FAN2	(1 << 5)

MODULE_AUTHOR("Massimo Dal Zotto (dz@debian.org)");
MODULE_DESCRIPTION("Driver for accessing SMM BIOS on Dell laptops");
MODULE_LICENSE("GPL");

static bool force;
module_param(force, bool, 0);
MODULE_PARM_DESC(force, "Force loading without checking for supported models");

static bool ignore_dmi;
module_param(ignore_dmi, bool, 0);
MODULE_PARM_DESC(ignore_dmi, "Continue probing hardware even if DMI data does not match");

static bool restricted;
module_param(restricted, bool, 0);
MODULE_PARM_DESC(restricted, "Allow fan control if SYS_ADMIN capability set");

static bool power_status;
module_param(power_status, bool, 0600);
MODULE_PARM_DESC(power_status, "Report power status in /proc/i8k");

static int fan_mult = I8K_FAN_MULT;
module_param(fan_mult, int, 0);
MODULE_PARM_DESC(fan_mult, "Factor to multiply fan speed with");

static int i8k_open_fs(struct inode *inode, struct file *file);
static long i8k_ioctl(struct file *, unsigned int, unsigned long);

static const struct file_operations i8k_fops = {
	.owner		= THIS_MODULE,
	.open		= i8k_open_fs,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
	.unlocked_ioctl	= i8k_ioctl,
};

struct smm_regs {
	unsigned int eax;
	unsigned int ebx __packed;
	unsigned int ecx __packed;
	unsigned int edx __packed;
	unsigned int esi __packed;
	unsigned int edi __packed;
};

static inline const char *i8k_get_dmi_data(int field)
{
	const char *dmi_data = dmi_get_system_info(field);

	return dmi_data && *dmi_data ? dmi_data : "?";
}

/*
 * Call the System Management Mode BIOS. Code provided by Jonathan Buzzard.
 */
static int i8k_smm(struct smm_regs *regs)
{
	int rc;
	int eax = regs->eax;
	cpumask_var_t old_mask;

	/* SMM requires CPU 0 */
	if (!alloc_cpumask_var(&old_mask, GFP_KERNEL))
		return -ENOMEM;
	cpumask_copy(old_mask, &current->cpus_allowed);
	set_cpus_allowed_ptr(current, cpumask_of(0));
	if (smp_processor_id() != 0) {
		rc = -EBUSY;
		goto out;
	}

#if defined(CONFIG_X86_64)
	asm volatile("pushq %%rax\n\t"
		"movl 0(%%rax),%%edx\n\t"
		"pushq %%rdx\n\t"
		"movl 4(%%rax),%%ebx\n\t"
		"movl 8(%%rax),%%ecx\n\t"
		"movl 12(%%rax),%%edx\n\t"
		"movl 16(%%rax),%%esi\n\t"
		"movl 20(%%rax),%%edi\n\t"
		"popq %%rax\n\t"
		"out %%al,$0xb2\n\t"
		"out %%al,$0x84\n\t"
		"xchgq %%rax,(%%rsp)\n\t"
		"movl %%ebx,4(%%rax)\n\t"
		"movl %%ecx,8(%%rax)\n\t"
		"movl %%edx,12(%%rax)\n\t"
		"movl %%esi,16(%%rax)\n\t"
		"movl %%edi,20(%%rax)\n\t"
		"popq %%rdx\n\t"
		"movl %%edx,0(%%rax)\n\t"
		"pushfq\n\t"
		"popq %%rax\n\t"
		"andl $1,%%eax\n"
		: "=a"(rc)
		:    "a"(regs)
		:    "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory");
#else
	asm volatile("pushl %%eax\n\t"
	    "movl 0(%%eax),%%edx\n\t"
	    "push %%edx\n\t"
	    "movl 4(%%eax),%%ebx\n\t"
	    "movl 8(%%eax),%%ecx\n\t"
	    "movl 12(%%eax),%%edx\n\t"
	    "movl 16(%%eax),%%esi\n\t"
	    "movl 20(%%eax),%%edi\n\t"
	    "popl %%eax\n\t"
	    "out %%al,$0xb2\n\t"
	    "out %%al,$0x84\n\t"
	    "xchgl %%eax,(%%esp)\n\t"
	    "movl %%ebx,4(%%eax)\n\t"
	    "movl %%ecx,8(%%eax)\n\t"
	    "movl %%edx,12(%%eax)\n\t"
	    "movl %%esi,16(%%eax)\n\t"
	    "movl %%edi,20(%%eax)\n\t"
	    "popl %%edx\n\t"
	    "movl %%edx,0(%%eax)\n\t"
	    "lahf\n\t"
	    "shrl $8,%%eax\n\t"
	    "andl $1,%%eax\n"
	    : "=a"(rc)
	    :    "a"(regs)
	    :    "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory");
#endif
	if (rc != 0 || (regs->eax & 0xffff) == 0xffff || regs->eax == eax)
		rc = -EINVAL;

out:
	set_cpus_allowed_ptr(current, old_mask);
	free_cpumask_var(old_mask);
	return rc;
}

/*
 * Read the bios version. Return the version as an integer corresponding
 * to the ascii value, for example "A17" is returned as 0x00413137.
 */
static int i8k_get_bios_version(void)
{
	struct smm_regs regs = { .eax = I8K_SMM_BIOS_VERSION, };

	return i8k_smm(&regs) ? : regs.eax;
}

/*
 * Read the Fn key status.
 */
static int i8k_get_fn_status(void)
{
	struct smm_regs regs = { .eax = I8K_SMM_FN_STATUS, };
	int rc;

	rc = i8k_smm(&regs);
	if (rc < 0)
		return rc;

	switch ((regs.eax >> I8K_FN_SHIFT) & I8K_FN_MASK) {
	case I8K_FN_UP:
		return I8K_VOL_UP;
	case I8K_FN_DOWN:
		return I8K_VOL_DOWN;
	case I8K_FN_MUTE:
		return I8K_VOL_MUTE;
	default:
		return 0;
	}
}

/*
 * Read the power status.
 */
static int i8k_get_power_status(void)
{
	struct smm_regs regs = { .eax = I8K_SMM_POWER_STATUS, };
	int rc;

	rc = i8k_smm(&regs);
	if (rc < 0)
		return rc;

	return (regs.eax & 0xff) == I8K_POWER_AC ? I8K_AC : I8K_BATTERY;
}

/*
 * Read the fan status.
 */
static int i8k_get_fan_status(int fan)
{
	struct smm_regs regs = { .eax = I8K_SMM_GET_FAN, };

	regs.ebx = fan & 0xff;
	return i8k_smm(&regs) ? : regs.eax & 0xff;
}

/*
 * Read the fan speed in RPM.
 */
static int i8k_get_fan_speed(int fan)
{
	struct smm_regs regs = { .eax = I8K_SMM_GET_SPEED, };

	regs.ebx = fan & 0xff;
	return i8k_smm(&regs) ? : (regs.eax & 0xffff) * fan_mult;
}

/*
 * Set the fan speed (off, low, high). Returns the new fan status.
 */
static int i8k_set_fan(int fan, int speed)
{
	struct smm_regs regs = { .eax = I8K_SMM_SET_FAN, };

	speed = (speed < 0) ? 0 : ((speed > I8K_FAN_MAX) ? I8K_FAN_MAX : speed);
	regs.ebx = (fan & 0xff) | (speed << 8);

	return i8k_smm(&regs) ? : i8k_get_fan_status(fan);
}

/*
 * Read the cpu temperature.
 */
static int i8k_get_temp(int sensor)
{
	struct smm_regs regs = { .eax = I8K_SMM_GET_TEMP, };
	int rc;
	int temp;

#ifdef I8K_TEMPERATURE_BUG
	static int prev[4];
#endif
	regs.ebx = sensor & 0xff;
	rc = i8k_smm(&regs);
	if (rc < 0)
		return rc;

	temp = regs.eax & 0xff;

#ifdef I8K_TEMPERATURE_BUG
	/*
	 * Sometimes the temperature sensor returns 0x99, which is out of range.
	 * In this case we return (once) the previous cached value. For example:
	 # 1003655137 00000058 00005a4b
	 # 1003655138 00000099 00003a80 <--- 0x99 = 153 degrees
	 # 1003655139 00000054 00005c52
	 */
	if (temp > I8K_MAX_TEMP) {
		temp = prev[sensor];
		prev[sensor] = I8K_MAX_TEMP;
	} else {
		prev[sensor] = temp;
	}
#endif

	return temp;
}

static int i8k_get_dell_signature(int req_fn)
{
	struct smm_regs regs = { .eax = req_fn, };
	int rc;

	rc = i8k_smm(&regs);
	if (rc < 0)
		return rc;

	return regs.eax == 1145651527 && regs.edx == 1145392204 ? 0 : -1;
}

static int
i8k_ioctl_unlocked(struct file *fp, unsigned int cmd, unsigned long arg)
{
	int val = 0;
	int speed;
	unsigned char buff[16];
	int __user *argp = (int __user *)arg;

	if (!argp)
		return -EINVAL;

	switch (cmd) {
	case I8K_BIOS_VERSION:
		val = i8k_get_bios_version();
		break;

	case I8K_MACHINE_ID:
		memset(buff, 0, 16);
		strlcpy(buff, i8k_get_dmi_data(DMI_PRODUCT_SERIAL),
			sizeof(buff));
		break;

	case I8K_FN_STATUS:
		val = i8k_get_fn_status();
		break;

	case I8K_POWER_STATUS:
		val = i8k_get_power_status();
		break;

	case I8K_GET_TEMP:
		val = i8k_get_temp(0);
		break;

	case I8K_GET_SPEED:
		if (copy_from_user(&val, argp, sizeof(int)))
			return -EFAULT;

		val = i8k_get_fan_speed(val);
		break;

	case I8K_GET_FAN:
		if (copy_from_user(&val, argp, sizeof(int)))
			return -EFAULT;

		val = i8k_get_fan_status(val);
		break;

	case I8K_SET_FAN:
		if (restricted && !capable(CAP_SYS_ADMIN))
			return -EPERM;

		if (copy_from_user(&val, argp, sizeof(int)))
			return -EFAULT;

		if (copy_from_user(&speed, argp + 1, sizeof(int)))
			return -EFAULT;

		val = i8k_set_fan(val, speed);
		break;

	default:
		return -EINVAL;
	}

	if (val < 0)
		return val;

	switch (cmd) {
	case I8K_BIOS_VERSION:
		if (copy_to_user(argp, &val, 4))
			return -EFAULT;

		break;
	case I8K_MACHINE_ID:
		if (copy_to_user(argp, buff, 16))
			return -EFAULT;

		break;
	default:
		if (copy_to_user(argp, &val, sizeof(int)))
			return -EFAULT;

		break;
	}

	return 0;
}

static long i8k_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
{
	long ret;

	mutex_lock(&i8k_mutex);
	ret = i8k_ioctl_unlocked(fp, cmd, arg);
	mutex_unlock(&i8k_mutex);

	return ret;
}

/*
 * Print the information for /proc/i8k.
 */
static int i8k_proc_show(struct seq_file *seq, void *offset)
{
	int fn_key, cpu_temp, ac_power;
	int left_fan, right_fan, left_speed, right_speed;

	cpu_temp	= i8k_get_temp(0);			/* 11100 µs */
	left_fan	= i8k_get_fan_status(I8K_FAN_LEFT);	/*   580 µs */
	right_fan	= i8k_get_fan_status(I8K_FAN_RIGHT);	/*   580 µs */
	left_speed	= i8k_get_fan_speed(I8K_FAN_LEFT);	/*   580 µs */
	right_speed	= i8k_get_fan_speed(I8K_FAN_RIGHT);	/*   580 µs */
	fn_key		= i8k_get_fn_status();			/*   750 µs */
	if (power_status)
		ac_power = i8k_get_power_status();		/* 14700 µs */
	else
		ac_power = -1;

	/*
	 * Info:
	 *
	 * 1)  Format version (this will change if format changes)
	 * 2)  BIOS version
	 * 3)  BIOS machine ID
	 * 4)  Cpu temperature
	 * 5)  Left fan status
	 * 6)  Right fan status
	 * 7)  Left fan speed
	 * 8)  Right fan speed
	 * 9)  AC power
	 * 10) Fn Key status
	 */
	return seq_printf(seq, "%s %s %s %d %d %d %d %d %d %d\n",
			  I8K_PROC_FMT,
			  bios_version,
			  i8k_get_dmi_data(DMI_PRODUCT_SERIAL),
			  cpu_temp,
			  left_fan, right_fan, left_speed, right_speed,
			  ac_power, fn_key);
}

static int i8k_open_fs(struct inode *inode, struct file *file)
{
	return single_open(file, i8k_proc_show, NULL);
}


/*
 * Hwmon interface
 */

static ssize_t i8k_hwmon_show_temp(struct device *dev,
				   struct device_attribute *devattr,
				   char *buf)
{
	int index = to_sensor_dev_attr(devattr)->index;
	int temp;

	temp = i8k_get_temp(index);
	if (temp < 0)
		return temp;
	return sprintf(buf, "%d\n", temp * 1000);
}

static ssize_t i8k_hwmon_show_fan(struct device *dev,
				  struct device_attribute *devattr,
				  char *buf)
{
	int index = to_sensor_dev_attr(devattr)->index;
	int fan_speed;

	fan_speed = i8k_get_fan_speed(index);
	if (fan_speed < 0)
		return fan_speed;
	return sprintf(buf, "%d\n", fan_speed);
}

static ssize_t i8k_hwmon_show_label(struct device *dev,
				    struct device_attribute *devattr,
				    char *buf)
{
	static const char *labels[3] = {
		"CPU",
		"Left Fan",
		"Right Fan",
	};
	int index = to_sensor_dev_attr(devattr)->index;

	return sprintf(buf, "%s\n", labels[index]);
}

static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 0);
static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 1);
static SENSOR_DEVICE_ATTR(temp3_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 2);
static SENSOR_DEVICE_ATTR(temp4_input, S_IRUGO, i8k_hwmon_show_temp, NULL, 3);
static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, i8k_hwmon_show_fan, NULL,
			  I8K_FAN_LEFT);
static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, i8k_hwmon_show_fan, NULL,
			  I8K_FAN_RIGHT);
static SENSOR_DEVICE_ATTR(temp1_label, S_IRUGO, i8k_hwmon_show_label, NULL, 0);
static SENSOR_DEVICE_ATTR(fan1_label, S_IRUGO, i8k_hwmon_show_label, NULL, 1);
static SENSOR_DEVICE_ATTR(fan2_label, S_IRUGO, i8k_hwmon_show_label, NULL, 2);

static struct attribute *i8k_attrs[] = {
	&sensor_dev_attr_temp1_input.dev_attr.attr,	/* 0 */
	&sensor_dev_attr_temp1_label.dev_attr.attr,	/* 1 */
	&sensor_dev_attr_temp2_input.dev_attr.attr,	/* 2 */
	&sensor_dev_attr_temp3_input.dev_attr.attr,	/* 3 */
	&sensor_dev_attr_temp4_input.dev_attr.attr,	/* 4 */
	&sensor_dev_attr_fan1_input.dev_attr.attr,	/* 5 */
	&sensor_dev_attr_fan1_label.dev_attr.attr,	/* 6 */
	&sensor_dev_attr_fan2_input.dev_attr.attr,	/* 7 */
	&sensor_dev_attr_fan2_label.dev_attr.attr,	/* 8 */
	NULL
};

static umode_t i8k_is_visible(struct kobject *kobj, struct attribute *attr,
			      int index)
{
	if ((index == 0 || index == 1) &&
	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP1))
		return 0;
	if (index == 2 && !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP2))
		return 0;
	if (index == 3 && !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP3))
		return 0;
	if (index == 4 && !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP4))
		return 0;
	if ((index == 5 || index == 6) &&
	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_FAN1))
		return 0;
	if ((index == 7 || index == 8) &&
	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_FAN2))
		return 0;

	return attr->mode;
}

static const struct attribute_group i8k_group = {
	.attrs = i8k_attrs,
	.is_visible = i8k_is_visible,
};
__ATTRIBUTE_GROUPS(i8k);

static int __init i8k_init_hwmon(void)
{
	int err;

	i8k_hwmon_flags = 0;

	/* CPU temperature attributes, if temperature reading is OK */
	err = i8k_get_temp(0);
	if (err >= 0)
		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP1;
	/* check for additional temperature sensors */
	err = i8k_get_temp(1);
	if (err >= 0)
		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP2;
	err = i8k_get_temp(2);
	if (err >= 0)
		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP3;
	err = i8k_get_temp(3);
	if (err >= 0)
		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP4;

	/* Left fan attributes, if left fan is present */
	err = i8k_get_fan_status(I8K_FAN_LEFT);
	if (err >= 0)
		i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN1;

	/* Right fan attributes, if right fan is present */
	err = i8k_get_fan_status(I8K_FAN_RIGHT);
	if (err >= 0)
		i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN2;

	i8k_hwmon_dev = hwmon_device_register_with_groups(NULL, "i8k", NULL,
							  i8k_groups);
	if (IS_ERR(i8k_hwmon_dev)) {
		err = PTR_ERR(i8k_hwmon_dev);
		i8k_hwmon_dev = NULL;
		pr_err("hwmon registration failed (%d)\n", err);
		return err;
	}
	return 0;
}

static struct dmi_system_id i8k_dmi_table[] __initdata = {
	{
		.ident = "Dell Inspiron",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer"),
			DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron"),
		},
	},
	{
		.ident = "Dell Latitude",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer"),
			DMI_MATCH(DMI_PRODUCT_NAME, "Latitude"),
		},
	},
	{
		.ident = "Dell Inspiron 2",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
			DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron"),
		},
	},
	{
		.ident = "Dell Latitude 2",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
			DMI_MATCH(DMI_PRODUCT_NAME, "Latitude"),
		},
	},
	{	/* UK Inspiron 6400  */
		.ident = "Dell Inspiron 3",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
			DMI_MATCH(DMI_PRODUCT_NAME, "MM061"),
		},
	},
	{
		.ident = "Dell Inspiron 3",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
			DMI_MATCH(DMI_PRODUCT_NAME, "MP061"),
		},
	},
	{
		.ident = "Dell Precision",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
			DMI_MATCH(DMI_PRODUCT_NAME, "Precision"),
		},
	},
	{
		.ident = "Dell Vostro",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
			DMI_MATCH(DMI_PRODUCT_NAME, "Vostro"),
		},
	},
	{
		.ident = "Dell XPS421",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
			DMI_MATCH(DMI_PRODUCT_NAME, "XPS L421X"),
		},
	},
	{
		.ident = "Dell Studio",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
			DMI_MATCH(DMI_PRODUCT_NAME, "Studio"),
		},
	},
	{
		.ident = "Dell XPS M140",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
			DMI_MATCH(DMI_PRODUCT_NAME, "MXC051"),
		},
	},
	{ }
};

/*
 * Probe for the presence of a supported laptop.
 */
static int __init i8k_probe(void)
{
	char buff[4];
	int version;

	/*
	 * Get DMI information
	 */
	if (!dmi_check_system(i8k_dmi_table)) {
		if (!ignore_dmi && !force)
			return -ENODEV;

		pr_info("not running on a supported Dell system.\n");
		pr_info("vendor=%s, model=%s, version=%s\n",
			i8k_get_dmi_data(DMI_SYS_VENDOR),
			i8k_get_dmi_data(DMI_PRODUCT_NAME),
			i8k_get_dmi_data(DMI_BIOS_VERSION));
	}

	strlcpy(bios_version, i8k_get_dmi_data(DMI_BIOS_VERSION),
		sizeof(bios_version));

	/*
	 * Get SMM Dell signature
	 */
	if (i8k_get_dell_signature(I8K_SMM_GET_DELL_SIG1) &&
	    i8k_get_dell_signature(I8K_SMM_GET_DELL_SIG2)) {
		pr_err("unable to get SMM Dell signature\n");
		if (!force)
			return -ENODEV;
	}

	/*
	 * Get SMM BIOS version.
	 */
	version = i8k_get_bios_version();
	if (version <= 0) {
		pr_warn("unable to get SMM BIOS version\n");
	} else {
		buff[0] = (version >> 16) & 0xff;
		buff[1] = (version >> 8) & 0xff;
		buff[2] = (version) & 0xff;
		buff[3] = '\0';
		/*
		 * If DMI BIOS version is unknown use SMM BIOS version.
		 */
		if (!dmi_get_system_info(DMI_BIOS_VERSION))
			strlcpy(bios_version, buff, sizeof(bios_version));

		/*
		 * Check if the two versions match.
		 */
		if (strncmp(buff, bios_version, sizeof(bios_version)) != 0)
			pr_warn("BIOS version mismatch: %s != %s\n",
				buff, bios_version);
	}

	return 0;
}

static int __init i8k_init(void)
{
	struct proc_dir_entry *proc_i8k;
	int err;

	/* Are we running on an supported laptop? */
	if (i8k_probe())
		return -ENODEV;

	/* Register the proc entry */
	proc_i8k = proc_create("i8k", 0, NULL, &i8k_fops);
	if (!proc_i8k)
		return -ENOENT;

	err = i8k_init_hwmon();
	if (err)
		goto exit_remove_proc;

	return 0;

 exit_remove_proc:
	remove_proc_entry("i8k", NULL);
	return err;
}

static void __exit i8k_exit(void)
{
	hwmon_device_unregister(i8k_hwmon_dev);
	remove_proc_entry("i8k", NULL);
}

module_init(i8k_init);
module_exit(i8k_exit);