1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * dell-smm-hwmon.c -- Linux driver for accessing the SMM BIOS on Dell laptops.
4  *
5  * Copyright (C) 2001  Massimo Dal Zotto <dz@debian.org>
6  *
7  * Hwmon integration:
8  * Copyright (C) 2011  Jean Delvare <jdelvare@suse.de>
9  * Copyright (C) 2013, 2014  Guenter Roeck <linux@roeck-us.net>
10  * Copyright (C) 2014, 2015  Pali Rohár <pali.rohar@gmail.com>
11  */
12 
13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14 
15 #include <linux/cpu.h>
16 #include <linux/delay.h>
17 #include <linux/module.h>
18 #include <linux/types.h>
19 #include <linux/init.h>
20 #include <linux/proc_fs.h>
21 #include <linux/seq_file.h>
22 #include <linux/dmi.h>
23 #include <linux/capability.h>
24 #include <linux/mutex.h>
25 #include <linux/hwmon.h>
26 #include <linux/hwmon-sysfs.h>
27 #include <linux/uaccess.h>
28 #include <linux/io.h>
29 #include <linux/sched.h>
30 #include <linux/ctype.h>
31 #include <linux/smp.h>
32 
33 #include <linux/i8k.h>
34 
35 #define I8K_SMM_FN_STATUS	0x0025
36 #define I8K_SMM_POWER_STATUS	0x0069
37 #define I8K_SMM_SET_FAN		0x01a3
38 #define I8K_SMM_GET_FAN		0x00a3
39 #define I8K_SMM_GET_SPEED	0x02a3
40 #define I8K_SMM_GET_FAN_TYPE	0x03a3
41 #define I8K_SMM_GET_NOM_SPEED	0x04a3
42 #define I8K_SMM_GET_TEMP	0x10a3
43 #define I8K_SMM_GET_TEMP_TYPE	0x11a3
44 #define I8K_SMM_GET_DELL_SIG1	0xfea3
45 #define I8K_SMM_GET_DELL_SIG2	0xffa3
46 
47 #define I8K_FAN_MULT		30
48 #define I8K_FAN_MAX_RPM		30000
49 #define I8K_MAX_TEMP		127
50 
51 #define I8K_FN_NONE		0x00
52 #define I8K_FN_UP		0x01
53 #define I8K_FN_DOWN		0x02
54 #define I8K_FN_MUTE		0x04
55 #define I8K_FN_MASK		0x07
56 #define I8K_FN_SHIFT		8
57 
58 #define I8K_POWER_AC		0x05
59 #define I8K_POWER_BATTERY	0x01
60 
61 static DEFINE_MUTEX(i8k_mutex);
62 static char bios_version[4];
63 static char bios_machineid[16];
64 static struct device *i8k_hwmon_dev;
65 static u32 i8k_hwmon_flags;
66 static uint i8k_fan_mult = I8K_FAN_MULT;
67 static uint i8k_pwm_mult;
68 static uint i8k_fan_max = I8K_FAN_HIGH;
69 static bool disallow_fan_type_call;
70 static bool disallow_fan_support;
71 
72 #define I8K_HWMON_HAVE_TEMP1	(1 << 0)
73 #define I8K_HWMON_HAVE_TEMP2	(1 << 1)
74 #define I8K_HWMON_HAVE_TEMP3	(1 << 2)
75 #define I8K_HWMON_HAVE_TEMP4	(1 << 3)
76 #define I8K_HWMON_HAVE_TEMP5	(1 << 4)
77 #define I8K_HWMON_HAVE_TEMP6	(1 << 5)
78 #define I8K_HWMON_HAVE_TEMP7	(1 << 6)
79 #define I8K_HWMON_HAVE_TEMP8	(1 << 7)
80 #define I8K_HWMON_HAVE_TEMP9	(1 << 8)
81 #define I8K_HWMON_HAVE_TEMP10	(1 << 9)
82 #define I8K_HWMON_HAVE_FAN1	(1 << 10)
83 #define I8K_HWMON_HAVE_FAN2	(1 << 11)
84 #define I8K_HWMON_HAVE_FAN3	(1 << 12)
85 
86 MODULE_AUTHOR("Massimo Dal Zotto (dz@debian.org)");
87 MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
88 MODULE_DESCRIPTION("Dell laptop SMM BIOS hwmon driver");
89 MODULE_LICENSE("GPL");
90 MODULE_ALIAS("i8k");
91 
92 static bool force;
93 module_param(force, bool, 0);
94 MODULE_PARM_DESC(force, "Force loading without checking for supported models");
95 
96 static bool ignore_dmi;
97 module_param(ignore_dmi, bool, 0);
98 MODULE_PARM_DESC(ignore_dmi, "Continue probing hardware even if DMI data does not match");
99 
100 #if IS_ENABLED(CONFIG_I8K)
101 static bool restricted = true;
102 module_param(restricted, bool, 0);
103 MODULE_PARM_DESC(restricted, "Restrict fan control and serial number to CAP_SYS_ADMIN (default: 1)");
104 
105 static bool power_status;
106 module_param(power_status, bool, 0600);
107 MODULE_PARM_DESC(power_status, "Report power status in /proc/i8k (default: 0)");
108 #endif
109 
110 static uint fan_mult;
111 module_param(fan_mult, uint, 0);
112 MODULE_PARM_DESC(fan_mult, "Factor to multiply fan speed with (default: autodetect)");
113 
114 static uint fan_max;
115 module_param(fan_max, uint, 0);
116 MODULE_PARM_DESC(fan_max, "Maximum configurable fan speed (default: autodetect)");
117 
118 struct smm_regs {
119 	unsigned int eax;
120 	unsigned int ebx __packed;
121 	unsigned int ecx __packed;
122 	unsigned int edx __packed;
123 	unsigned int esi __packed;
124 	unsigned int edi __packed;
125 };
126 
127 static inline const char *i8k_get_dmi_data(int field)
128 {
129 	const char *dmi_data = dmi_get_system_info(field);
130 
131 	return dmi_data && *dmi_data ? dmi_data : "?";
132 }
133 
134 /*
135  * Call the System Management Mode BIOS. Code provided by Jonathan Buzzard.
136  */
137 static int i8k_smm_func(void *par)
138 {
139 	int rc;
140 	struct smm_regs *regs = par;
141 	int eax = regs->eax;
142 
143 #ifdef DEBUG
144 	int ebx = regs->ebx;
145 	unsigned long duration;
146 	ktime_t calltime, delta, rettime;
147 
148 	calltime = ktime_get();
149 #endif
150 
151 	/* SMM requires CPU 0 */
152 	if (smp_processor_id() != 0)
153 		return -EBUSY;
154 
155 #if defined(CONFIG_X86_64)
156 	asm volatile("pushq %%rax\n\t"
157 		"movl 0(%%rax),%%edx\n\t"
158 		"pushq %%rdx\n\t"
159 		"movl 4(%%rax),%%ebx\n\t"
160 		"movl 8(%%rax),%%ecx\n\t"
161 		"movl 12(%%rax),%%edx\n\t"
162 		"movl 16(%%rax),%%esi\n\t"
163 		"movl 20(%%rax),%%edi\n\t"
164 		"popq %%rax\n\t"
165 		"out %%al,$0xb2\n\t"
166 		"out %%al,$0x84\n\t"
167 		"xchgq %%rax,(%%rsp)\n\t"
168 		"movl %%ebx,4(%%rax)\n\t"
169 		"movl %%ecx,8(%%rax)\n\t"
170 		"movl %%edx,12(%%rax)\n\t"
171 		"movl %%esi,16(%%rax)\n\t"
172 		"movl %%edi,20(%%rax)\n\t"
173 		"popq %%rdx\n\t"
174 		"movl %%edx,0(%%rax)\n\t"
175 		"pushfq\n\t"
176 		"popq %%rax\n\t"
177 		"andl $1,%%eax\n"
178 		: "=a"(rc)
179 		:    "a"(regs)
180 		:    "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory");
181 #else
182 	asm volatile("pushl %%eax\n\t"
183 	    "movl 0(%%eax),%%edx\n\t"
184 	    "push %%edx\n\t"
185 	    "movl 4(%%eax),%%ebx\n\t"
186 	    "movl 8(%%eax),%%ecx\n\t"
187 	    "movl 12(%%eax),%%edx\n\t"
188 	    "movl 16(%%eax),%%esi\n\t"
189 	    "movl 20(%%eax),%%edi\n\t"
190 	    "popl %%eax\n\t"
191 	    "out %%al,$0xb2\n\t"
192 	    "out %%al,$0x84\n\t"
193 	    "xchgl %%eax,(%%esp)\n\t"
194 	    "movl %%ebx,4(%%eax)\n\t"
195 	    "movl %%ecx,8(%%eax)\n\t"
196 	    "movl %%edx,12(%%eax)\n\t"
197 	    "movl %%esi,16(%%eax)\n\t"
198 	    "movl %%edi,20(%%eax)\n\t"
199 	    "popl %%edx\n\t"
200 	    "movl %%edx,0(%%eax)\n\t"
201 	    "lahf\n\t"
202 	    "shrl $8,%%eax\n\t"
203 	    "andl $1,%%eax\n"
204 	    : "=a"(rc)
205 	    :    "a"(regs)
206 	    :    "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory");
207 #endif
208 	if (rc != 0 || (regs->eax & 0xffff) == 0xffff || regs->eax == eax)
209 		rc = -EINVAL;
210 
211 #ifdef DEBUG
212 	rettime = ktime_get();
213 	delta = ktime_sub(rettime, calltime);
214 	duration = ktime_to_ns(delta) >> 10;
215 	pr_debug("smm(0x%.4x 0x%.4x) = 0x%.4x  (took %7lu usecs)\n", eax, ebx,
216 		(rc ? 0xffff : regs->eax & 0xffff), duration);
217 #endif
218 
219 	return rc;
220 }
221 
222 /*
223  * Call the System Management Mode BIOS.
224  */
225 static int i8k_smm(struct smm_regs *regs)
226 {
227 	int ret;
228 
229 	get_online_cpus();
230 	ret = smp_call_on_cpu(0, i8k_smm_func, regs, true);
231 	put_online_cpus();
232 
233 	return ret;
234 }
235 
236 /*
237  * Read the fan status.
238  */
239 static int i8k_get_fan_status(int fan)
240 {
241 	struct smm_regs regs = { .eax = I8K_SMM_GET_FAN, };
242 
243 	if (disallow_fan_support)
244 		return -EINVAL;
245 
246 	regs.ebx = fan & 0xff;
247 	return i8k_smm(&regs) ? : regs.eax & 0xff;
248 }
249 
250 /*
251  * Read the fan speed in RPM.
252  */
253 static int i8k_get_fan_speed(int fan)
254 {
255 	struct smm_regs regs = { .eax = I8K_SMM_GET_SPEED, };
256 
257 	if (disallow_fan_support)
258 		return -EINVAL;
259 
260 	regs.ebx = fan & 0xff;
261 	return i8k_smm(&regs) ? : (regs.eax & 0xffff) * i8k_fan_mult;
262 }
263 
264 /*
265  * Read the fan type.
266  */
267 static int _i8k_get_fan_type(int fan)
268 {
269 	struct smm_regs regs = { .eax = I8K_SMM_GET_FAN_TYPE, };
270 
271 	if (disallow_fan_support || disallow_fan_type_call)
272 		return -EINVAL;
273 
274 	regs.ebx = fan & 0xff;
275 	return i8k_smm(&regs) ? : regs.eax & 0xff;
276 }
277 
278 static int i8k_get_fan_type(int fan)
279 {
280 	/* I8K_SMM_GET_FAN_TYPE SMM call is expensive, so cache values */
281 	static int types[3] = { INT_MIN, INT_MIN, INT_MIN };
282 
283 	if (types[fan] == INT_MIN)
284 		types[fan] = _i8k_get_fan_type(fan);
285 
286 	return types[fan];
287 }
288 
289 /*
290  * Read the fan nominal rpm for specific fan speed.
291  */
292 static int i8k_get_fan_nominal_speed(int fan, int speed)
293 {
294 	struct smm_regs regs = { .eax = I8K_SMM_GET_NOM_SPEED, };
295 
296 	if (disallow_fan_support)
297 		return -EINVAL;
298 
299 	regs.ebx = (fan & 0xff) | (speed << 8);
300 	return i8k_smm(&regs) ? : (regs.eax & 0xffff) * i8k_fan_mult;
301 }
302 
303 /*
304  * Set the fan speed (off, low, high). Returns the new fan status.
305  */
306 static int i8k_set_fan(int fan, int speed)
307 {
308 	struct smm_regs regs = { .eax = I8K_SMM_SET_FAN, };
309 
310 	if (disallow_fan_support)
311 		return -EINVAL;
312 
313 	speed = (speed < 0) ? 0 : ((speed > i8k_fan_max) ? i8k_fan_max : speed);
314 	regs.ebx = (fan & 0xff) | (speed << 8);
315 
316 	return i8k_smm(&regs) ? : i8k_get_fan_status(fan);
317 }
318 
319 static int i8k_get_temp_type(int sensor)
320 {
321 	struct smm_regs regs = { .eax = I8K_SMM_GET_TEMP_TYPE, };
322 
323 	regs.ebx = sensor & 0xff;
324 	return i8k_smm(&regs) ? : regs.eax & 0xff;
325 }
326 
327 /*
328  * Read the cpu temperature.
329  */
330 static int _i8k_get_temp(int sensor)
331 {
332 	struct smm_regs regs = {
333 		.eax = I8K_SMM_GET_TEMP,
334 		.ebx = sensor & 0xff,
335 	};
336 
337 	return i8k_smm(&regs) ? : regs.eax & 0xff;
338 }
339 
340 static int i8k_get_temp(int sensor)
341 {
342 	int temp = _i8k_get_temp(sensor);
343 
344 	/*
345 	 * Sometimes the temperature sensor returns 0x99, which is out of range.
346 	 * In this case we retry (once) before returning an error.
347 	 # 1003655137 00000058 00005a4b
348 	 # 1003655138 00000099 00003a80 <--- 0x99 = 153 degrees
349 	 # 1003655139 00000054 00005c52
350 	 */
351 	if (temp == 0x99) {
352 		msleep(100);
353 		temp = _i8k_get_temp(sensor);
354 	}
355 	/*
356 	 * Return -ENODATA for all invalid temperatures.
357 	 *
358 	 * Known instances are the 0x99 value as seen above as well as
359 	 * 0xc1 (193), which may be returned when trying to read the GPU
360 	 * temperature if the system supports a GPU and it is currently
361 	 * turned off.
362 	 */
363 	if (temp > I8K_MAX_TEMP)
364 		return -ENODATA;
365 
366 	return temp;
367 }
368 
369 static int i8k_get_dell_signature(int req_fn)
370 {
371 	struct smm_regs regs = { .eax = req_fn, };
372 	int rc;
373 
374 	rc = i8k_smm(&regs);
375 	if (rc < 0)
376 		return rc;
377 
378 	return regs.eax == 1145651527 && regs.edx == 1145392204 ? 0 : -1;
379 }
380 
381 #if IS_ENABLED(CONFIG_I8K)
382 
383 /*
384  * Read the Fn key status.
385  */
386 static int i8k_get_fn_status(void)
387 {
388 	struct smm_regs regs = { .eax = I8K_SMM_FN_STATUS, };
389 	int rc;
390 
391 	rc = i8k_smm(&regs);
392 	if (rc < 0)
393 		return rc;
394 
395 	switch ((regs.eax >> I8K_FN_SHIFT) & I8K_FN_MASK) {
396 	case I8K_FN_UP:
397 		return I8K_VOL_UP;
398 	case I8K_FN_DOWN:
399 		return I8K_VOL_DOWN;
400 	case I8K_FN_MUTE:
401 		return I8K_VOL_MUTE;
402 	default:
403 		return 0;
404 	}
405 }
406 
407 /*
408  * Read the power status.
409  */
410 static int i8k_get_power_status(void)
411 {
412 	struct smm_regs regs = { .eax = I8K_SMM_POWER_STATUS, };
413 	int rc;
414 
415 	rc = i8k_smm(&regs);
416 	if (rc < 0)
417 		return rc;
418 
419 	return (regs.eax & 0xff) == I8K_POWER_AC ? I8K_AC : I8K_BATTERY;
420 }
421 
422 /*
423  * Procfs interface
424  */
425 
426 static int
427 i8k_ioctl_unlocked(struct file *fp, unsigned int cmd, unsigned long arg)
428 {
429 	int val = 0;
430 	int speed;
431 	unsigned char buff[16];
432 	int __user *argp = (int __user *)arg;
433 
434 	if (!argp)
435 		return -EINVAL;
436 
437 	switch (cmd) {
438 	case I8K_BIOS_VERSION:
439 		if (!isdigit(bios_version[0]) || !isdigit(bios_version[1]) ||
440 		    !isdigit(bios_version[2]))
441 			return -EINVAL;
442 
443 		val = (bios_version[0] << 16) |
444 				(bios_version[1] << 8) | bios_version[2];
445 		break;
446 
447 	case I8K_MACHINE_ID:
448 		if (restricted && !capable(CAP_SYS_ADMIN))
449 			return -EPERM;
450 
451 		memset(buff, 0, sizeof(buff));
452 		strlcpy(buff, bios_machineid, sizeof(buff));
453 		break;
454 
455 	case I8K_FN_STATUS:
456 		val = i8k_get_fn_status();
457 		break;
458 
459 	case I8K_POWER_STATUS:
460 		val = i8k_get_power_status();
461 		break;
462 
463 	case I8K_GET_TEMP:
464 		val = i8k_get_temp(0);
465 		break;
466 
467 	case I8K_GET_SPEED:
468 		if (copy_from_user(&val, argp, sizeof(int)))
469 			return -EFAULT;
470 
471 		val = i8k_get_fan_speed(val);
472 		break;
473 
474 	case I8K_GET_FAN:
475 		if (copy_from_user(&val, argp, sizeof(int)))
476 			return -EFAULT;
477 
478 		val = i8k_get_fan_status(val);
479 		break;
480 
481 	case I8K_SET_FAN:
482 		if (restricted && !capable(CAP_SYS_ADMIN))
483 			return -EPERM;
484 
485 		if (copy_from_user(&val, argp, sizeof(int)))
486 			return -EFAULT;
487 
488 		if (copy_from_user(&speed, argp + 1, sizeof(int)))
489 			return -EFAULT;
490 
491 		val = i8k_set_fan(val, speed);
492 		break;
493 
494 	default:
495 		return -EINVAL;
496 	}
497 
498 	if (val < 0)
499 		return val;
500 
501 	switch (cmd) {
502 	case I8K_BIOS_VERSION:
503 		if (copy_to_user(argp, &val, 4))
504 			return -EFAULT;
505 
506 		break;
507 	case I8K_MACHINE_ID:
508 		if (copy_to_user(argp, buff, 16))
509 			return -EFAULT;
510 
511 		break;
512 	default:
513 		if (copy_to_user(argp, &val, sizeof(int)))
514 			return -EFAULT;
515 
516 		break;
517 	}
518 
519 	return 0;
520 }
521 
522 static long i8k_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
523 {
524 	long ret;
525 
526 	mutex_lock(&i8k_mutex);
527 	ret = i8k_ioctl_unlocked(fp, cmd, arg);
528 	mutex_unlock(&i8k_mutex);
529 
530 	return ret;
531 }
532 
533 /*
534  * Print the information for /proc/i8k.
535  */
536 static int i8k_proc_show(struct seq_file *seq, void *offset)
537 {
538 	int fn_key, cpu_temp, ac_power;
539 	int left_fan, right_fan, left_speed, right_speed;
540 
541 	cpu_temp	= i8k_get_temp(0);			/* 11100 µs */
542 	left_fan	= i8k_get_fan_status(I8K_FAN_LEFT);	/*   580 µs */
543 	right_fan	= i8k_get_fan_status(I8K_FAN_RIGHT);	/*   580 µs */
544 	left_speed	= i8k_get_fan_speed(I8K_FAN_LEFT);	/*   580 µs */
545 	right_speed	= i8k_get_fan_speed(I8K_FAN_RIGHT);	/*   580 µs */
546 	fn_key		= i8k_get_fn_status();			/*   750 µs */
547 	if (power_status)
548 		ac_power = i8k_get_power_status();		/* 14700 µs */
549 	else
550 		ac_power = -1;
551 
552 	/*
553 	 * Info:
554 	 *
555 	 * 1)  Format version (this will change if format changes)
556 	 * 2)  BIOS version
557 	 * 3)  BIOS machine ID
558 	 * 4)  Cpu temperature
559 	 * 5)  Left fan status
560 	 * 6)  Right fan status
561 	 * 7)  Left fan speed
562 	 * 8)  Right fan speed
563 	 * 9)  AC power
564 	 * 10) Fn Key status
565 	 */
566 	seq_printf(seq, "%s %s %s %d %d %d %d %d %d %d\n",
567 		   I8K_PROC_FMT,
568 		   bios_version,
569 		   (restricted && !capable(CAP_SYS_ADMIN)) ? "-1" : bios_machineid,
570 		   cpu_temp,
571 		   left_fan, right_fan, left_speed, right_speed,
572 		   ac_power, fn_key);
573 
574 	return 0;
575 }
576 
577 static int i8k_open_fs(struct inode *inode, struct file *file)
578 {
579 	return single_open(file, i8k_proc_show, NULL);
580 }
581 
582 static const struct file_operations i8k_fops = {
583 	.owner		= THIS_MODULE,
584 	.open		= i8k_open_fs,
585 	.read		= seq_read,
586 	.llseek		= seq_lseek,
587 	.release	= single_release,
588 	.unlocked_ioctl	= i8k_ioctl,
589 };
590 
591 static void __init i8k_init_procfs(void)
592 {
593 	/* Register the proc entry */
594 	proc_create("i8k", 0, NULL, &i8k_fops);
595 }
596 
597 static void __exit i8k_exit_procfs(void)
598 {
599 	remove_proc_entry("i8k", NULL);
600 }
601 
602 #else
603 
604 static inline void __init i8k_init_procfs(void)
605 {
606 }
607 
608 static inline void __exit i8k_exit_procfs(void)
609 {
610 }
611 
612 #endif
613 
614 /*
615  * Hwmon interface
616  */
617 
618 static ssize_t i8k_hwmon_temp_label_show(struct device *dev,
619 					 struct device_attribute *devattr,
620 					 char *buf)
621 {
622 	static const char * const labels[] = {
623 		"CPU",
624 		"GPU",
625 		"SODIMM",
626 		"Other",
627 		"Ambient",
628 		"Other",
629 	};
630 	int index = to_sensor_dev_attr(devattr)->index;
631 	int type;
632 
633 	type = i8k_get_temp_type(index);
634 	if (type < 0)
635 		return type;
636 	if (type >= ARRAY_SIZE(labels))
637 		type = ARRAY_SIZE(labels) - 1;
638 	return sprintf(buf, "%s\n", labels[type]);
639 }
640 
641 static ssize_t i8k_hwmon_temp_show(struct device *dev,
642 				   struct device_attribute *devattr,
643 				   char *buf)
644 {
645 	int index = to_sensor_dev_attr(devattr)->index;
646 	int temp;
647 
648 	temp = i8k_get_temp(index);
649 	if (temp < 0)
650 		return temp;
651 	return sprintf(buf, "%d\n", temp * 1000);
652 }
653 
654 static ssize_t i8k_hwmon_fan_label_show(struct device *dev,
655 					struct device_attribute *devattr,
656 					char *buf)
657 {
658 	static const char * const labels[] = {
659 		"Processor Fan",
660 		"Motherboard Fan",
661 		"Video Fan",
662 		"Power Supply Fan",
663 		"Chipset Fan",
664 		"Other Fan",
665 	};
666 	int index = to_sensor_dev_attr(devattr)->index;
667 	bool dock = false;
668 	int type;
669 
670 	type = i8k_get_fan_type(index);
671 	if (type < 0)
672 		return type;
673 
674 	if (type & 0x10) {
675 		dock = true;
676 		type &= 0x0F;
677 	}
678 
679 	if (type >= ARRAY_SIZE(labels))
680 		type = (ARRAY_SIZE(labels) - 1);
681 
682 	return sprintf(buf, "%s%s\n", (dock ? "Docking " : ""), labels[type]);
683 }
684 
685 static ssize_t i8k_hwmon_fan_show(struct device *dev,
686 				  struct device_attribute *devattr, char *buf)
687 {
688 	int index = to_sensor_dev_attr(devattr)->index;
689 	int fan_speed;
690 
691 	fan_speed = i8k_get_fan_speed(index);
692 	if (fan_speed < 0)
693 		return fan_speed;
694 	return sprintf(buf, "%d\n", fan_speed);
695 }
696 
697 static ssize_t i8k_hwmon_pwm_show(struct device *dev,
698 				  struct device_attribute *devattr, char *buf)
699 {
700 	int index = to_sensor_dev_attr(devattr)->index;
701 	int status;
702 
703 	status = i8k_get_fan_status(index);
704 	if (status < 0)
705 		return -EIO;
706 	return sprintf(buf, "%d\n", clamp_val(status * i8k_pwm_mult, 0, 255));
707 }
708 
709 static ssize_t i8k_hwmon_pwm_store(struct device *dev,
710 				   struct device_attribute *attr,
711 				   const char *buf, size_t count)
712 {
713 	int index = to_sensor_dev_attr(attr)->index;
714 	unsigned long val;
715 	int err;
716 
717 	err = kstrtoul(buf, 10, &val);
718 	if (err)
719 		return err;
720 	val = clamp_val(DIV_ROUND_CLOSEST(val, i8k_pwm_mult), 0, i8k_fan_max);
721 
722 	mutex_lock(&i8k_mutex);
723 	err = i8k_set_fan(index, val);
724 	mutex_unlock(&i8k_mutex);
725 
726 	return err < 0 ? -EIO : count;
727 }
728 
729 static SENSOR_DEVICE_ATTR_RO(temp1_input, i8k_hwmon_temp, 0);
730 static SENSOR_DEVICE_ATTR_RO(temp1_label, i8k_hwmon_temp_label, 0);
731 static SENSOR_DEVICE_ATTR_RO(temp2_input, i8k_hwmon_temp, 1);
732 static SENSOR_DEVICE_ATTR_RO(temp2_label, i8k_hwmon_temp_label, 1);
733 static SENSOR_DEVICE_ATTR_RO(temp3_input, i8k_hwmon_temp, 2);
734 static SENSOR_DEVICE_ATTR_RO(temp3_label, i8k_hwmon_temp_label, 2);
735 static SENSOR_DEVICE_ATTR_RO(temp4_input, i8k_hwmon_temp, 3);
736 static SENSOR_DEVICE_ATTR_RO(temp4_label, i8k_hwmon_temp_label, 3);
737 static SENSOR_DEVICE_ATTR_RO(temp5_input, i8k_hwmon_temp, 4);
738 static SENSOR_DEVICE_ATTR_RO(temp5_label, i8k_hwmon_temp_label, 4);
739 static SENSOR_DEVICE_ATTR_RO(temp6_input, i8k_hwmon_temp, 5);
740 static SENSOR_DEVICE_ATTR_RO(temp6_label, i8k_hwmon_temp_label, 5);
741 static SENSOR_DEVICE_ATTR_RO(temp7_input, i8k_hwmon_temp, 6);
742 static SENSOR_DEVICE_ATTR_RO(temp7_label, i8k_hwmon_temp_label, 6);
743 static SENSOR_DEVICE_ATTR_RO(temp8_input, i8k_hwmon_temp, 7);
744 static SENSOR_DEVICE_ATTR_RO(temp8_label, i8k_hwmon_temp_label, 7);
745 static SENSOR_DEVICE_ATTR_RO(temp9_input, i8k_hwmon_temp, 8);
746 static SENSOR_DEVICE_ATTR_RO(temp9_label, i8k_hwmon_temp_label, 8);
747 static SENSOR_DEVICE_ATTR_RO(temp10_input, i8k_hwmon_temp, 9);
748 static SENSOR_DEVICE_ATTR_RO(temp10_label, i8k_hwmon_temp_label, 9);
749 static SENSOR_DEVICE_ATTR_RO(fan1_input, i8k_hwmon_fan, 0);
750 static SENSOR_DEVICE_ATTR_RO(fan1_label, i8k_hwmon_fan_label, 0);
751 static SENSOR_DEVICE_ATTR_RW(pwm1, i8k_hwmon_pwm, 0);
752 static SENSOR_DEVICE_ATTR_RO(fan2_input, i8k_hwmon_fan, 1);
753 static SENSOR_DEVICE_ATTR_RO(fan2_label, i8k_hwmon_fan_label, 1);
754 static SENSOR_DEVICE_ATTR_RW(pwm2, i8k_hwmon_pwm, 1);
755 static SENSOR_DEVICE_ATTR_RO(fan3_input, i8k_hwmon_fan, 2);
756 static SENSOR_DEVICE_ATTR_RO(fan3_label, i8k_hwmon_fan_label, 2);
757 static SENSOR_DEVICE_ATTR_RW(pwm3, i8k_hwmon_pwm, 2);
758 
759 static struct attribute *i8k_attrs[] = {
760 	&sensor_dev_attr_temp1_input.dev_attr.attr,	/* 0 */
761 	&sensor_dev_attr_temp1_label.dev_attr.attr,	/* 1 */
762 	&sensor_dev_attr_temp2_input.dev_attr.attr,	/* 2 */
763 	&sensor_dev_attr_temp2_label.dev_attr.attr,	/* 3 */
764 	&sensor_dev_attr_temp3_input.dev_attr.attr,	/* 4 */
765 	&sensor_dev_attr_temp3_label.dev_attr.attr,	/* 5 */
766 	&sensor_dev_attr_temp4_input.dev_attr.attr,	/* 6 */
767 	&sensor_dev_attr_temp4_label.dev_attr.attr,	/* 7 */
768 	&sensor_dev_attr_temp5_input.dev_attr.attr,	/* 8 */
769 	&sensor_dev_attr_temp5_label.dev_attr.attr,	/* 9 */
770 	&sensor_dev_attr_temp6_input.dev_attr.attr,	/* 10 */
771 	&sensor_dev_attr_temp6_label.dev_attr.attr,	/* 11 */
772 	&sensor_dev_attr_temp7_input.dev_attr.attr,	/* 12 */
773 	&sensor_dev_attr_temp7_label.dev_attr.attr,	/* 13 */
774 	&sensor_dev_attr_temp8_input.dev_attr.attr,	/* 14 */
775 	&sensor_dev_attr_temp8_label.dev_attr.attr,	/* 15 */
776 	&sensor_dev_attr_temp9_input.dev_attr.attr,	/* 16 */
777 	&sensor_dev_attr_temp9_label.dev_attr.attr,	/* 17 */
778 	&sensor_dev_attr_temp10_input.dev_attr.attr,	/* 18 */
779 	&sensor_dev_attr_temp10_label.dev_attr.attr,	/* 19 */
780 	&sensor_dev_attr_fan1_input.dev_attr.attr,	/* 20 */
781 	&sensor_dev_attr_fan1_label.dev_attr.attr,	/* 21 */
782 	&sensor_dev_attr_pwm1.dev_attr.attr,		/* 22 */
783 	&sensor_dev_attr_fan2_input.dev_attr.attr,	/* 23 */
784 	&sensor_dev_attr_fan2_label.dev_attr.attr,	/* 24 */
785 	&sensor_dev_attr_pwm2.dev_attr.attr,		/* 25 */
786 	&sensor_dev_attr_fan3_input.dev_attr.attr,	/* 26 */
787 	&sensor_dev_attr_fan3_label.dev_attr.attr,	/* 27 */
788 	&sensor_dev_attr_pwm3.dev_attr.attr,		/* 28 */
789 	NULL
790 };
791 
792 static umode_t i8k_is_visible(struct kobject *kobj, struct attribute *attr,
793 			      int index)
794 {
795 	if (disallow_fan_support && index >= 8)
796 		return 0;
797 	if (disallow_fan_type_call &&
798 	    (index == 9 || index == 12 || index == 15))
799 		return 0;
800 	if (index >= 0 && index <= 1 &&
801 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP1))
802 		return 0;
803 	if (index >= 2 && index <= 3 &&
804 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP2))
805 		return 0;
806 	if (index >= 4 && index <= 5 &&
807 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP3))
808 		return 0;
809 	if (index >= 6 && index <= 7 &&
810 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP4))
811 		return 0;
812 	if (index >= 8 && index <= 9 &&
813 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP5))
814 		return 0;
815 	if (index >= 10 && index <= 11 &&
816 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP6))
817 		return 0;
818 	if (index >= 12 && index <= 13 &&
819 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP7))
820 		return 0;
821 	if (index >= 14 && index <= 15 &&
822 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP8))
823 		return 0;
824 	if (index >= 16 && index <= 17 &&
825 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP9))
826 		return 0;
827 	if (index >= 18 && index <= 19 &&
828 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP10))
829 		return 0;
830 
831 	if (index >= 20 && index <= 22 &&
832 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_FAN1))
833 		return 0;
834 	if (index >= 23 && index <= 25 &&
835 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_FAN2))
836 		return 0;
837 	if (index >= 26 && index <= 28 &&
838 	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_FAN3))
839 		return 0;
840 
841 	return attr->mode;
842 }
843 
844 static const struct attribute_group i8k_group = {
845 	.attrs = i8k_attrs,
846 	.is_visible = i8k_is_visible,
847 };
848 __ATTRIBUTE_GROUPS(i8k);
849 
850 static int __init i8k_init_hwmon(void)
851 {
852 	int err;
853 
854 	i8k_hwmon_flags = 0;
855 
856 	/* CPU temperature attributes, if temperature type is OK */
857 	err = i8k_get_temp_type(0);
858 	if (err >= 0)
859 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP1;
860 	/* check for additional temperature sensors */
861 	err = i8k_get_temp_type(1);
862 	if (err >= 0)
863 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP2;
864 	err = i8k_get_temp_type(2);
865 	if (err >= 0)
866 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP3;
867 	err = i8k_get_temp_type(3);
868 	if (err >= 0)
869 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP4;
870 	err = i8k_get_temp_type(4);
871 	if (err >= 0)
872 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP5;
873 	err = i8k_get_temp_type(5);
874 	if (err >= 0)
875 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP6;
876 	err = i8k_get_temp_type(6);
877 	if (err >= 0)
878 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP7;
879 	err = i8k_get_temp_type(7);
880 	if (err >= 0)
881 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP8;
882 	err = i8k_get_temp_type(8);
883 	if (err >= 0)
884 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP9;
885 	err = i8k_get_temp_type(9);
886 	if (err >= 0)
887 		i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP10;
888 
889 	/* First fan attributes, if fan status or type is OK */
890 	err = i8k_get_fan_status(0);
891 	if (err < 0)
892 		err = i8k_get_fan_type(0);
893 	if (err >= 0)
894 		i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN1;
895 
896 	/* Second fan attributes, if fan status or type is OK */
897 	err = i8k_get_fan_status(1);
898 	if (err < 0)
899 		err = i8k_get_fan_type(1);
900 	if (err >= 0)
901 		i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN2;
902 
903 	/* Third fan attributes, if fan status or type is OK */
904 	err = i8k_get_fan_status(2);
905 	if (err < 0)
906 		err = i8k_get_fan_type(2);
907 	if (err >= 0)
908 		i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN3;
909 
910 	i8k_hwmon_dev = hwmon_device_register_with_groups(NULL, "dell_smm",
911 							  NULL, i8k_groups);
912 	if (IS_ERR(i8k_hwmon_dev)) {
913 		err = PTR_ERR(i8k_hwmon_dev);
914 		i8k_hwmon_dev = NULL;
915 		pr_err("hwmon registration failed (%d)\n", err);
916 		return err;
917 	}
918 	return 0;
919 }
920 
921 struct i8k_config_data {
922 	uint fan_mult;
923 	uint fan_max;
924 };
925 
926 enum i8k_configs {
927 	DELL_LATITUDE_D520,
928 	DELL_PRECISION_490,
929 	DELL_STUDIO,
930 	DELL_XPS,
931 };
932 
933 static const struct i8k_config_data i8k_config_data[] = {
934 	[DELL_LATITUDE_D520] = {
935 		.fan_mult = 1,
936 		.fan_max = I8K_FAN_TURBO,
937 	},
938 	[DELL_PRECISION_490] = {
939 		.fan_mult = 1,
940 		.fan_max = I8K_FAN_TURBO,
941 	},
942 	[DELL_STUDIO] = {
943 		.fan_mult = 1,
944 		.fan_max = I8K_FAN_HIGH,
945 	},
946 	[DELL_XPS] = {
947 		.fan_mult = 1,
948 		.fan_max = I8K_FAN_HIGH,
949 	},
950 };
951 
952 static const struct dmi_system_id i8k_dmi_table[] __initconst = {
953 	{
954 		.ident = "Dell Inspiron",
955 		.matches = {
956 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer"),
957 			DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron"),
958 		},
959 	},
960 	{
961 		.ident = "Dell Latitude",
962 		.matches = {
963 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer"),
964 			DMI_MATCH(DMI_PRODUCT_NAME, "Latitude"),
965 		},
966 	},
967 	{
968 		.ident = "Dell Inspiron 2",
969 		.matches = {
970 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
971 			DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron"),
972 		},
973 	},
974 	{
975 		.ident = "Dell Latitude D520",
976 		.matches = {
977 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
978 			DMI_MATCH(DMI_PRODUCT_NAME, "Latitude D520"),
979 		},
980 		.driver_data = (void *)&i8k_config_data[DELL_LATITUDE_D520],
981 	},
982 	{
983 		.ident = "Dell Latitude 2",
984 		.matches = {
985 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
986 			DMI_MATCH(DMI_PRODUCT_NAME, "Latitude"),
987 		},
988 	},
989 	{	/* UK Inspiron 6400  */
990 		.ident = "Dell Inspiron 3",
991 		.matches = {
992 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
993 			DMI_MATCH(DMI_PRODUCT_NAME, "MM061"),
994 		},
995 	},
996 	{
997 		.ident = "Dell Inspiron 3",
998 		.matches = {
999 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1000 			DMI_MATCH(DMI_PRODUCT_NAME, "MP061"),
1001 		},
1002 	},
1003 	{
1004 		.ident = "Dell Precision 490",
1005 		.matches = {
1006 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1007 			DMI_MATCH(DMI_PRODUCT_NAME,
1008 				  "Precision WorkStation 490"),
1009 		},
1010 		.driver_data = (void *)&i8k_config_data[DELL_PRECISION_490],
1011 	},
1012 	{
1013 		.ident = "Dell Precision",
1014 		.matches = {
1015 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1016 			DMI_MATCH(DMI_PRODUCT_NAME, "Precision"),
1017 		},
1018 	},
1019 	{
1020 		.ident = "Dell Vostro",
1021 		.matches = {
1022 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1023 			DMI_MATCH(DMI_PRODUCT_NAME, "Vostro"),
1024 		},
1025 	},
1026 	{
1027 		.ident = "Dell XPS421",
1028 		.matches = {
1029 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1030 			DMI_MATCH(DMI_PRODUCT_NAME, "XPS L421X"),
1031 		},
1032 	},
1033 	{
1034 		.ident = "Dell Studio",
1035 		.matches = {
1036 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1037 			DMI_MATCH(DMI_PRODUCT_NAME, "Studio"),
1038 		},
1039 		.driver_data = (void *)&i8k_config_data[DELL_STUDIO],
1040 	},
1041 	{
1042 		.ident = "Dell XPS 13",
1043 		.matches = {
1044 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1045 			DMI_MATCH(DMI_PRODUCT_NAME, "XPS13"),
1046 		},
1047 		.driver_data = (void *)&i8k_config_data[DELL_XPS],
1048 	},
1049 	{
1050 		.ident = "Dell XPS M140",
1051 		.matches = {
1052 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1053 			DMI_MATCH(DMI_PRODUCT_NAME, "MXC051"),
1054 		},
1055 		.driver_data = (void *)&i8k_config_data[DELL_XPS],
1056 	},
1057 	{
1058 		.ident = "Dell XPS 15 9560",
1059 		.matches = {
1060 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1061 			DMI_MATCH(DMI_PRODUCT_NAME, "XPS 15 9560"),
1062 		},
1063 	},
1064 	{
1065 		.ident = "Dell XPS 15 9570",
1066 		.matches = {
1067 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1068 			DMI_MATCH(DMI_PRODUCT_NAME, "XPS 15 9570"),
1069 		},
1070 	},
1071 	{ }
1072 };
1073 
1074 MODULE_DEVICE_TABLE(dmi, i8k_dmi_table);
1075 
1076 /*
1077  * On some machines once I8K_SMM_GET_FAN_TYPE is issued then CPU fan speed
1078  * randomly going up and down due to bug in Dell SMM or BIOS. Here is blacklist
1079  * of affected Dell machines for which we disallow I8K_SMM_GET_FAN_TYPE call.
1080  * See bug: https://bugzilla.kernel.org/show_bug.cgi?id=100121
1081  */
1082 static const struct dmi_system_id i8k_blacklist_fan_type_dmi_table[] __initconst = {
1083 	{
1084 		.ident = "Dell Studio XPS 8000",
1085 		.matches = {
1086 			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1087 			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "Studio XPS 8000"),
1088 		},
1089 	},
1090 	{
1091 		.ident = "Dell Studio XPS 8100",
1092 		.matches = {
1093 			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1094 			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "Studio XPS 8100"),
1095 		},
1096 	},
1097 	{
1098 		.ident = "Dell Inspiron 580",
1099 		.matches = {
1100 			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1101 			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "Inspiron 580 "),
1102 		},
1103 	},
1104 	{ }
1105 };
1106 
1107 /*
1108  * On some machines all fan related SMM functions implemented by Dell BIOS
1109  * firmware freeze kernel for about 500ms. Until Dell fixes these problems fan
1110  * support for affected blacklisted Dell machines stay disabled.
1111  * See bug: https://bugzilla.kernel.org/show_bug.cgi?id=195751
1112  */
1113 static struct dmi_system_id i8k_blacklist_fan_support_dmi_table[] __initdata = {
1114 	{
1115 		.ident = "Dell Inspiron 7720",
1116 		.matches = {
1117 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1118 			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "Inspiron 7720"),
1119 		},
1120 	},
1121 	{
1122 		.ident = "Dell Vostro 3360",
1123 		.matches = {
1124 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1125 			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "Vostro 3360"),
1126 		},
1127 	},
1128 	{
1129 		.ident = "Dell XPS13 9333",
1130 		.matches = {
1131 			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
1132 			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "XPS13 9333"),
1133 		},
1134 	},
1135 	{ }
1136 };
1137 
1138 /*
1139  * Probe for the presence of a supported laptop.
1140  */
1141 static int __init i8k_probe(void)
1142 {
1143 	const struct dmi_system_id *id;
1144 	int fan, ret;
1145 
1146 	/*
1147 	 * Get DMI information
1148 	 */
1149 	if (!dmi_check_system(i8k_dmi_table)) {
1150 		if (!ignore_dmi && !force)
1151 			return -ENODEV;
1152 
1153 		pr_info("not running on a supported Dell system.\n");
1154 		pr_info("vendor=%s, model=%s, version=%s\n",
1155 			i8k_get_dmi_data(DMI_SYS_VENDOR),
1156 			i8k_get_dmi_data(DMI_PRODUCT_NAME),
1157 			i8k_get_dmi_data(DMI_BIOS_VERSION));
1158 	}
1159 
1160 	if (dmi_check_system(i8k_blacklist_fan_support_dmi_table)) {
1161 		pr_warn("broken Dell BIOS detected, disallow fan support\n");
1162 		if (!force)
1163 			disallow_fan_support = true;
1164 	}
1165 
1166 	if (dmi_check_system(i8k_blacklist_fan_type_dmi_table)) {
1167 		pr_warn("broken Dell BIOS detected, disallow fan type call\n");
1168 		if (!force)
1169 			disallow_fan_type_call = true;
1170 	}
1171 
1172 	strlcpy(bios_version, i8k_get_dmi_data(DMI_BIOS_VERSION),
1173 		sizeof(bios_version));
1174 	strlcpy(bios_machineid, i8k_get_dmi_data(DMI_PRODUCT_SERIAL),
1175 		sizeof(bios_machineid));
1176 
1177 	/*
1178 	 * Get SMM Dell signature
1179 	 */
1180 	if (i8k_get_dell_signature(I8K_SMM_GET_DELL_SIG1) &&
1181 	    i8k_get_dell_signature(I8K_SMM_GET_DELL_SIG2)) {
1182 		pr_err("unable to get SMM Dell signature\n");
1183 		if (!force)
1184 			return -ENODEV;
1185 	}
1186 
1187 	/*
1188 	 * Set fan multiplier and maximal fan speed from dmi config
1189 	 * Values specified in module parameters override values from dmi
1190 	 */
1191 	id = dmi_first_match(i8k_dmi_table);
1192 	if (id && id->driver_data) {
1193 		const struct i8k_config_data *conf = id->driver_data;
1194 		if (!fan_mult && conf->fan_mult)
1195 			fan_mult = conf->fan_mult;
1196 		if (!fan_max && conf->fan_max)
1197 			fan_max = conf->fan_max;
1198 	}
1199 
1200 	i8k_fan_max = fan_max ? : I8K_FAN_HIGH;	/* Must not be 0 */
1201 	i8k_pwm_mult = DIV_ROUND_UP(255, i8k_fan_max);
1202 
1203 	if (!fan_mult) {
1204 		/*
1205 		 * Autodetect fan multiplier based on nominal rpm
1206 		 * If fan reports rpm value too high then set multiplier to 1
1207 		 */
1208 		for (fan = 0; fan < 2; ++fan) {
1209 			ret = i8k_get_fan_nominal_speed(fan, i8k_fan_max);
1210 			if (ret < 0)
1211 				continue;
1212 			if (ret > I8K_FAN_MAX_RPM)
1213 				i8k_fan_mult = 1;
1214 			break;
1215 		}
1216 	} else {
1217 		/* Fan multiplier was specified in module param or in dmi */
1218 		i8k_fan_mult = fan_mult;
1219 	}
1220 
1221 	return 0;
1222 }
1223 
1224 static int __init i8k_init(void)
1225 {
1226 	int err;
1227 
1228 	/* Are we running on an supported laptop? */
1229 	if (i8k_probe())
1230 		return -ENODEV;
1231 
1232 	err = i8k_init_hwmon();
1233 	if (err)
1234 		return err;
1235 
1236 	i8k_init_procfs();
1237 	return 0;
1238 }
1239 
1240 static void __exit i8k_exit(void)
1241 {
1242 	hwmon_device_unregister(i8k_hwmon_dev);
1243 	i8k_exit_procfs();
1244 }
1245 
1246 module_init(i8k_init);
1247 module_exit(i8k_exit);
1248