1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  Common functions for kernel modules using Dell SMBIOS
4  *
5  *  Copyright (c) Red Hat <mjg@redhat.com>
6  *  Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>
7  *  Copyright (c) 2014 Pali Rohár <pali@kernel.org>
8  *
9  *  Based on documentation in the libsmbios package:
10  *  Copyright (C) 2005-2014 Dell Inc.
11  */
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/capability.h>
17 #include <linux/dmi.h>
18 #include <linux/err.h>
19 #include <linux/mutex.h>
20 #include <linux/platform_device.h>
21 #include <linux/slab.h>
22 #include "dell-smbios.h"
23 
24 static u32 da_supported_commands;
25 static int da_num_tokens;
26 static struct platform_device *platform_device;
27 static struct calling_interface_token *da_tokens;
28 static struct device_attribute *token_location_attrs;
29 static struct device_attribute *token_value_attrs;
30 static struct attribute **token_attrs;
31 static DEFINE_MUTEX(smbios_mutex);
32 
33 struct smbios_device {
34 	struct list_head list;
35 	struct device *device;
36 	int (*call_fn)(struct calling_interface_buffer *arg);
37 };
38 
39 struct smbios_call {
40 	u32 need_capability;
41 	int cmd_class;
42 	int cmd_select;
43 };
44 
45 /* calls that are whitelisted for given capabilities */
46 static struct smbios_call call_whitelist[] = {
47 	/* generally tokens are allowed, but may be further filtered or
48 	 * restricted by token blacklist or whitelist
49 	 */
50 	{CAP_SYS_ADMIN,	CLASS_TOKEN_READ,	SELECT_TOKEN_STD},
51 	{CAP_SYS_ADMIN,	CLASS_TOKEN_READ,	SELECT_TOKEN_AC},
52 	{CAP_SYS_ADMIN,	CLASS_TOKEN_READ,	SELECT_TOKEN_BAT},
53 	{CAP_SYS_ADMIN,	CLASS_TOKEN_WRITE,	SELECT_TOKEN_STD},
54 	{CAP_SYS_ADMIN,	CLASS_TOKEN_WRITE,	SELECT_TOKEN_AC},
55 	{CAP_SYS_ADMIN,	CLASS_TOKEN_WRITE,	SELECT_TOKEN_BAT},
56 	/* used by userspace: fwupdate */
57 	{CAP_SYS_ADMIN, CLASS_ADMIN_PROP,	SELECT_ADMIN_PROP},
58 	/* used by userspace: fwupd */
59 	{CAP_SYS_ADMIN,	CLASS_INFO,		SELECT_DOCK},
60 	{CAP_SYS_ADMIN,	CLASS_FLASH_INTERFACE,	SELECT_FLASH_INTERFACE},
61 };
62 
63 /* calls that are explicitly blacklisted */
64 static struct smbios_call call_blacklist[] = {
65 	{0x0000,  1,  7}, /* manufacturing use */
66 	{0x0000,  6,  5}, /* manufacturing use */
67 	{0x0000, 11,  3}, /* write once */
68 	{0x0000, 11,  7}, /* write once */
69 	{0x0000, 11, 11}, /* write once */
70 	{0x0000, 19, -1}, /* diagnostics */
71 	/* handled by kernel: dell-laptop */
72 	{0x0000, CLASS_INFO, SELECT_RFKILL},
73 	{0x0000, CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT},
74 };
75 
76 struct token_range {
77 	u32 need_capability;
78 	u16 min;
79 	u16 max;
80 };
81 
82 /* tokens that are whitelisted for given capabilities */
83 static struct token_range token_whitelist[] = {
84 	/* used by userspace: fwupdate */
85 	{CAP_SYS_ADMIN,	CAPSULE_EN_TOKEN,	CAPSULE_DIS_TOKEN},
86 	/* can indicate to userspace that WMI is needed */
87 	{0x0000,	WSMT_EN_TOKEN,		WSMT_DIS_TOKEN}
88 };
89 
90 /* tokens that are explicitly blacklisted */
91 static struct token_range token_blacklist[] = {
92 	{0x0000, 0x0058, 0x0059}, /* ME use */
93 	{0x0000, 0x00CD, 0x00D0}, /* raid shadow copy */
94 	{0x0000, 0x013A, 0x01FF}, /* sata shadow copy */
95 	{0x0000, 0x0175, 0x0176}, /* write once */
96 	{0x0000, 0x0195, 0x0197}, /* diagnostics */
97 	{0x0000, 0x01DC, 0x01DD}, /* manufacturing use */
98 	{0x0000, 0x027D, 0x0284}, /* diagnostics */
99 	{0x0000, 0x02E3, 0x02E3}, /* manufacturing use */
100 	{0x0000, 0x02FF, 0x02FF}, /* manufacturing use */
101 	{0x0000, 0x0300, 0x0302}, /* manufacturing use */
102 	{0x0000, 0x0325, 0x0326}, /* manufacturing use */
103 	{0x0000, 0x0332, 0x0335}, /* fan control */
104 	{0x0000, 0x0350, 0x0350}, /* manufacturing use */
105 	{0x0000, 0x0363, 0x0363}, /* manufacturing use */
106 	{0x0000, 0x0368, 0x0368}, /* manufacturing use */
107 	{0x0000, 0x03F6, 0x03F7}, /* manufacturing use */
108 	{0x0000, 0x049E, 0x049F}, /* manufacturing use */
109 	{0x0000, 0x04A0, 0x04A3}, /* disagnostics */
110 	{0x0000, 0x04E6, 0x04E7}, /* manufacturing use */
111 	{0x0000, 0x4000, 0x7FFF}, /* internal BIOS use */
112 	{0x0000, 0x9000, 0x9001}, /* internal BIOS use */
113 	{0x0000, 0xA000, 0xBFFF}, /* write only */
114 	{0x0000, 0xEFF0, 0xEFFF}, /* internal BIOS use */
115 	/* handled by kernel: dell-laptop */
116 	{0x0000, BRIGHTNESS_TOKEN,	BRIGHTNESS_TOKEN},
117 	{0x0000, KBD_LED_OFF_TOKEN,	KBD_LED_AUTO_TOKEN},
118 	{0x0000, KBD_LED_AC_TOKEN,	KBD_LED_AC_TOKEN},
119 	{0x0000, KBD_LED_AUTO_25_TOKEN,	KBD_LED_AUTO_75_TOKEN},
120 	{0x0000, KBD_LED_AUTO_100_TOKEN,	KBD_LED_AUTO_100_TOKEN},
121 	{0x0000, GLOBAL_MIC_MUTE_ENABLE,	GLOBAL_MIC_MUTE_DISABLE},
122 };
123 
124 static LIST_HEAD(smbios_device_list);
125 
126 int dell_smbios_error(int value)
127 {
128 	switch (value) {
129 	case 0: /* Completed successfully */
130 		return 0;
131 	case -1: /* Completed with error */
132 		return -EIO;
133 	case -2: /* Function not supported */
134 		return -ENXIO;
135 	default: /* Unknown error */
136 		return -EINVAL;
137 	}
138 }
139 EXPORT_SYMBOL_GPL(dell_smbios_error);
140 
141 int dell_smbios_register_device(struct device *d, void *call_fn)
142 {
143 	struct smbios_device *priv;
144 
145 	priv = devm_kzalloc(d, sizeof(struct smbios_device), GFP_KERNEL);
146 	if (!priv)
147 		return -ENOMEM;
148 	get_device(d);
149 	priv->device = d;
150 	priv->call_fn = call_fn;
151 	mutex_lock(&smbios_mutex);
152 	list_add_tail(&priv->list, &smbios_device_list);
153 	mutex_unlock(&smbios_mutex);
154 	dev_dbg(d, "Added device: %s\n", d->driver->name);
155 	return 0;
156 }
157 EXPORT_SYMBOL_GPL(dell_smbios_register_device);
158 
159 void dell_smbios_unregister_device(struct device *d)
160 {
161 	struct smbios_device *priv;
162 
163 	mutex_lock(&smbios_mutex);
164 	list_for_each_entry(priv, &smbios_device_list, list) {
165 		if (priv->device == d) {
166 			list_del(&priv->list);
167 			put_device(d);
168 			break;
169 		}
170 	}
171 	mutex_unlock(&smbios_mutex);
172 	dev_dbg(d, "Remove device: %s\n", d->driver->name);
173 }
174 EXPORT_SYMBOL_GPL(dell_smbios_unregister_device);
175 
176 int dell_smbios_call_filter(struct device *d,
177 			    struct calling_interface_buffer *buffer)
178 {
179 	u16 t = 0;
180 	int i;
181 
182 	/* can't make calls over 30 */
183 	if (buffer->cmd_class > 30) {
184 		dev_dbg(d, "class too big: %u\n", buffer->cmd_class);
185 		return -EINVAL;
186 	}
187 
188 	/* supported calls on the particular system */
189 	if (!(da_supported_commands & (1 << buffer->cmd_class))) {
190 		dev_dbg(d, "invalid command, supported commands: 0x%8x\n",
191 			da_supported_commands);
192 		return -EINVAL;
193 	}
194 
195 	/* match against call blacklist  */
196 	for (i = 0; i < ARRAY_SIZE(call_blacklist); i++) {
197 		if (buffer->cmd_class != call_blacklist[i].cmd_class)
198 			continue;
199 		if (buffer->cmd_select != call_blacklist[i].cmd_select &&
200 		    call_blacklist[i].cmd_select != -1)
201 			continue;
202 		dev_dbg(d, "blacklisted command: %u/%u\n",
203 			buffer->cmd_class, buffer->cmd_select);
204 		return -EINVAL;
205 	}
206 
207 	/* if a token call, find token ID */
208 
209 	if ((buffer->cmd_class == CLASS_TOKEN_READ ||
210 	     buffer->cmd_class == CLASS_TOKEN_WRITE) &&
211 	     buffer->cmd_select < 3) {
212 		/* tokens enabled ? */
213 		if (!da_tokens) {
214 			dev_dbg(d, "no token support on this system\n");
215 			return -EINVAL;
216 		}
217 
218 		/* find the matching token ID */
219 		for (i = 0; i < da_num_tokens; i++) {
220 			if (da_tokens[i].location != buffer->input[0])
221 				continue;
222 			t = da_tokens[i].tokenID;
223 			break;
224 		}
225 
226 		/* token call; but token didn't exist */
227 		if (!t) {
228 			dev_dbg(d, "token at location %04x doesn't exist\n",
229 				buffer->input[0]);
230 			return -EINVAL;
231 		}
232 
233 		/* match against token blacklist */
234 		for (i = 0; i < ARRAY_SIZE(token_blacklist); i++) {
235 			if (!token_blacklist[i].min || !token_blacklist[i].max)
236 				continue;
237 			if (t >= token_blacklist[i].min &&
238 			    t <= token_blacklist[i].max)
239 				return -EINVAL;
240 		}
241 
242 		/* match against token whitelist */
243 		for (i = 0; i < ARRAY_SIZE(token_whitelist); i++) {
244 			if (!token_whitelist[i].min || !token_whitelist[i].max)
245 				continue;
246 			if (t < token_whitelist[i].min ||
247 			    t > token_whitelist[i].max)
248 				continue;
249 			if (!token_whitelist[i].need_capability ||
250 			    capable(token_whitelist[i].need_capability)) {
251 				dev_dbg(d, "whitelisted token: %x\n", t);
252 				return 0;
253 			}
254 
255 		}
256 	}
257 	/* match against call whitelist */
258 	for (i = 0; i < ARRAY_SIZE(call_whitelist); i++) {
259 		if (buffer->cmd_class != call_whitelist[i].cmd_class)
260 			continue;
261 		if (buffer->cmd_select != call_whitelist[i].cmd_select)
262 			continue;
263 		if (!call_whitelist[i].need_capability ||
264 		    capable(call_whitelist[i].need_capability)) {
265 			dev_dbg(d, "whitelisted capable command: %u/%u\n",
266 			buffer->cmd_class, buffer->cmd_select);
267 			return 0;
268 		}
269 		dev_dbg(d, "missing capability %d for %u/%u\n",
270 			call_whitelist[i].need_capability,
271 			buffer->cmd_class, buffer->cmd_select);
272 
273 	}
274 
275 	/* not in a whitelist, only allow processes with capabilities */
276 	if (capable(CAP_SYS_RAWIO)) {
277 		dev_dbg(d, "Allowing %u/%u due to CAP_SYS_RAWIO\n",
278 			buffer->cmd_class, buffer->cmd_select);
279 		return 0;
280 	}
281 
282 	return -EACCES;
283 }
284 EXPORT_SYMBOL_GPL(dell_smbios_call_filter);
285 
286 int dell_smbios_call(struct calling_interface_buffer *buffer)
287 {
288 	int (*call_fn)(struct calling_interface_buffer *) = NULL;
289 	struct device *selected_dev = NULL;
290 	struct smbios_device *priv;
291 	int ret;
292 
293 	mutex_lock(&smbios_mutex);
294 	list_for_each_entry(priv, &smbios_device_list, list) {
295 		if (!selected_dev || priv->device->id >= selected_dev->id) {
296 			dev_dbg(priv->device, "Trying device ID: %d\n",
297 				priv->device->id);
298 			call_fn = priv->call_fn;
299 			selected_dev = priv->device;
300 		}
301 	}
302 
303 	if (!selected_dev) {
304 		ret = -ENODEV;
305 		pr_err("No dell-smbios drivers are loaded\n");
306 		goto out_smbios_call;
307 	}
308 
309 	ret = call_fn(buffer);
310 
311 out_smbios_call:
312 	mutex_unlock(&smbios_mutex);
313 	return ret;
314 }
315 EXPORT_SYMBOL_GPL(dell_smbios_call);
316 
317 struct calling_interface_token *dell_smbios_find_token(int tokenid)
318 {
319 	int i;
320 
321 	if (!da_tokens)
322 		return NULL;
323 
324 	for (i = 0; i < da_num_tokens; i++) {
325 		if (da_tokens[i].tokenID == tokenid)
326 			return &da_tokens[i];
327 	}
328 
329 	return NULL;
330 }
331 EXPORT_SYMBOL_GPL(dell_smbios_find_token);
332 
333 static BLOCKING_NOTIFIER_HEAD(dell_laptop_chain_head);
334 
335 int dell_laptop_register_notifier(struct notifier_block *nb)
336 {
337 	return blocking_notifier_chain_register(&dell_laptop_chain_head, nb);
338 }
339 EXPORT_SYMBOL_GPL(dell_laptop_register_notifier);
340 
341 int dell_laptop_unregister_notifier(struct notifier_block *nb)
342 {
343 	return blocking_notifier_chain_unregister(&dell_laptop_chain_head, nb);
344 }
345 EXPORT_SYMBOL_GPL(dell_laptop_unregister_notifier);
346 
347 void dell_laptop_call_notifier(unsigned long action, void *data)
348 {
349 	blocking_notifier_call_chain(&dell_laptop_chain_head, action, data);
350 }
351 EXPORT_SYMBOL_GPL(dell_laptop_call_notifier);
352 
353 static void __init parse_da_table(const struct dmi_header *dm)
354 {
355 	/* Final token is a terminator, so we don't want to copy it */
356 	int tokens = (dm->length-11)/sizeof(struct calling_interface_token)-1;
357 	struct calling_interface_token *new_da_tokens;
358 	struct calling_interface_structure *table =
359 		container_of(dm, struct calling_interface_structure, header);
360 
361 	/*
362 	 * 4 bytes of table header, plus 7 bytes of Dell header
363 	 * plus at least 6 bytes of entry
364 	 */
365 
366 	if (dm->length < 17)
367 		return;
368 
369 	da_supported_commands = table->supportedCmds;
370 
371 	new_da_tokens = krealloc(da_tokens, (da_num_tokens + tokens) *
372 				 sizeof(struct calling_interface_token),
373 				 GFP_KERNEL);
374 
375 	if (!new_da_tokens)
376 		return;
377 	da_tokens = new_da_tokens;
378 
379 	memcpy(da_tokens+da_num_tokens, table->tokens,
380 	       sizeof(struct calling_interface_token) * tokens);
381 
382 	da_num_tokens += tokens;
383 }
384 
385 static void zero_duplicates(struct device *dev)
386 {
387 	int i, j;
388 
389 	for (i = 0; i < da_num_tokens; i++) {
390 		if (da_tokens[i].tokenID == 0)
391 			continue;
392 		for (j = i+1; j < da_num_tokens; j++) {
393 			if (da_tokens[j].tokenID == 0)
394 				continue;
395 			if (da_tokens[i].tokenID == da_tokens[j].tokenID) {
396 				dev_dbg(dev, "Zeroing dup token ID %x(%x/%x)\n",
397 					da_tokens[j].tokenID,
398 					da_tokens[j].location,
399 					da_tokens[j].value);
400 				da_tokens[j].tokenID = 0;
401 			}
402 		}
403 	}
404 }
405 
406 static void __init find_tokens(const struct dmi_header *dm, void *dummy)
407 {
408 	switch (dm->type) {
409 	case 0xd4: /* Indexed IO */
410 	case 0xd5: /* Protected Area Type 1 */
411 	case 0xd6: /* Protected Area Type 2 */
412 		break;
413 	case 0xda: /* Calling interface */
414 		parse_da_table(dm);
415 		break;
416 	}
417 }
418 
419 static int match_attribute(struct device *dev,
420 			   struct device_attribute *attr)
421 {
422 	int i;
423 
424 	for (i = 0; i < da_num_tokens * 2; i++) {
425 		if (!token_attrs[i])
426 			continue;
427 		if (strcmp(token_attrs[i]->name, attr->attr.name) == 0)
428 			return i/2;
429 	}
430 	dev_dbg(dev, "couldn't match: %s\n", attr->attr.name);
431 	return -EINVAL;
432 }
433 
434 static ssize_t location_show(struct device *dev,
435 			     struct device_attribute *attr, char *buf)
436 {
437 	int i;
438 
439 	if (!capable(CAP_SYS_ADMIN))
440 		return -EPERM;
441 
442 	i = match_attribute(dev, attr);
443 	if (i > 0)
444 		return scnprintf(buf, PAGE_SIZE, "%08x", da_tokens[i].location);
445 	return 0;
446 }
447 
448 static ssize_t value_show(struct device *dev,
449 			  struct device_attribute *attr, char *buf)
450 {
451 	int i;
452 
453 	if (!capable(CAP_SYS_ADMIN))
454 		return -EPERM;
455 
456 	i = match_attribute(dev, attr);
457 	if (i > 0)
458 		return scnprintf(buf, PAGE_SIZE, "%08x", da_tokens[i].value);
459 	return 0;
460 }
461 
462 static struct attribute_group smbios_attribute_group = {
463 	.name = "tokens"
464 };
465 
466 static struct platform_driver platform_driver = {
467 	.driver = {
468 		.name = "dell-smbios",
469 	},
470 };
471 
472 static int build_tokens_sysfs(struct platform_device *dev)
473 {
474 	char *location_name;
475 	char *value_name;
476 	size_t size;
477 	int ret;
478 	int i, j;
479 
480 	/* (number of tokens  + 1 for null terminated */
481 	size = sizeof(struct device_attribute) * (da_num_tokens + 1);
482 	token_location_attrs = kzalloc(size, GFP_KERNEL);
483 	if (!token_location_attrs)
484 		return -ENOMEM;
485 	token_value_attrs = kzalloc(size, GFP_KERNEL);
486 	if (!token_value_attrs)
487 		goto out_allocate_value;
488 
489 	/* need to store both location and value + terminator*/
490 	size = sizeof(struct attribute *) * ((2 * da_num_tokens) + 1);
491 	token_attrs = kzalloc(size, GFP_KERNEL);
492 	if (!token_attrs)
493 		goto out_allocate_attrs;
494 
495 	for (i = 0, j = 0; i < da_num_tokens; i++) {
496 		/* skip empty */
497 		if (da_tokens[i].tokenID == 0)
498 			continue;
499 		/* add location */
500 		location_name = kasprintf(GFP_KERNEL, "%04x_location",
501 					  da_tokens[i].tokenID);
502 		if (location_name == NULL)
503 			goto out_unwind_strings;
504 		sysfs_attr_init(&token_location_attrs[i].attr);
505 		token_location_attrs[i].attr.name = location_name;
506 		token_location_attrs[i].attr.mode = 0444;
507 		token_location_attrs[i].show = location_show;
508 		token_attrs[j++] = &token_location_attrs[i].attr;
509 
510 		/* add value */
511 		value_name = kasprintf(GFP_KERNEL, "%04x_value",
512 				       da_tokens[i].tokenID);
513 		if (value_name == NULL)
514 			goto loop_fail_create_value;
515 		sysfs_attr_init(&token_value_attrs[i].attr);
516 		token_value_attrs[i].attr.name = value_name;
517 		token_value_attrs[i].attr.mode = 0444;
518 		token_value_attrs[i].show = value_show;
519 		token_attrs[j++] = &token_value_attrs[i].attr;
520 		continue;
521 
522 loop_fail_create_value:
523 		kfree(location_name);
524 		goto out_unwind_strings;
525 	}
526 	smbios_attribute_group.attrs = token_attrs;
527 
528 	ret = sysfs_create_group(&dev->dev.kobj, &smbios_attribute_group);
529 	if (ret)
530 		goto out_unwind_strings;
531 	return 0;
532 
533 out_unwind_strings:
534 	while (i--) {
535 		kfree(token_location_attrs[i].attr.name);
536 		kfree(token_value_attrs[i].attr.name);
537 	}
538 	kfree(token_attrs);
539 out_allocate_attrs:
540 	kfree(token_value_attrs);
541 out_allocate_value:
542 	kfree(token_location_attrs);
543 
544 	return -ENOMEM;
545 }
546 
547 static void free_group(struct platform_device *pdev)
548 {
549 	int i;
550 
551 	sysfs_remove_group(&pdev->dev.kobj,
552 				&smbios_attribute_group);
553 	for (i = 0; i < da_num_tokens; i++) {
554 		kfree(token_location_attrs[i].attr.name);
555 		kfree(token_value_attrs[i].attr.name);
556 	}
557 	kfree(token_attrs);
558 	kfree(token_value_attrs);
559 	kfree(token_location_attrs);
560 }
561 
562 static int __init dell_smbios_init(void)
563 {
564 	int ret, wmi, smm;
565 
566 	if (!dmi_find_device(DMI_DEV_TYPE_OEM_STRING, "Dell System", NULL) &&
567 	    !dmi_find_device(DMI_DEV_TYPE_OEM_STRING, "www.dell.com", NULL)) {
568 		pr_err("Unable to run on non-Dell system\n");
569 		return -ENODEV;
570 	}
571 
572 	dmi_walk(find_tokens, NULL);
573 
574 	ret = platform_driver_register(&platform_driver);
575 	if (ret)
576 		goto fail_platform_driver;
577 
578 	platform_device = platform_device_alloc("dell-smbios", 0);
579 	if (!platform_device) {
580 		ret = -ENOMEM;
581 		goto fail_platform_device_alloc;
582 	}
583 	ret = platform_device_add(platform_device);
584 	if (ret)
585 		goto fail_platform_device_add;
586 
587 	/* register backends */
588 	wmi = init_dell_smbios_wmi();
589 	if (wmi)
590 		pr_debug("Failed to initialize WMI backend: %d\n", wmi);
591 	smm = init_dell_smbios_smm();
592 	if (smm)
593 		pr_debug("Failed to initialize SMM backend: %d\n", smm);
594 	if (wmi && smm) {
595 		pr_err("No SMBIOS backends available (wmi: %d, smm: %d)\n",
596 			wmi, smm);
597 		ret = -ENODEV;
598 		goto fail_create_group;
599 	}
600 
601 	if (da_tokens)  {
602 		/* duplicate tokens will cause problems building sysfs files */
603 		zero_duplicates(&platform_device->dev);
604 
605 		ret = build_tokens_sysfs(platform_device);
606 		if (ret)
607 			goto fail_sysfs;
608 	}
609 
610 	return 0;
611 
612 fail_sysfs:
613 	free_group(platform_device);
614 
615 fail_create_group:
616 	platform_device_del(platform_device);
617 
618 fail_platform_device_add:
619 	platform_device_put(platform_device);
620 
621 fail_platform_device_alloc:
622 	platform_driver_unregister(&platform_driver);
623 
624 fail_platform_driver:
625 	kfree(da_tokens);
626 	return ret;
627 }
628 
629 static void __exit dell_smbios_exit(void)
630 {
631 	exit_dell_smbios_wmi();
632 	exit_dell_smbios_smm();
633 	mutex_lock(&smbios_mutex);
634 	if (platform_device) {
635 		if (da_tokens)
636 			free_group(platform_device);
637 		platform_device_unregister(platform_device);
638 		platform_driver_unregister(&platform_driver);
639 	}
640 	kfree(da_tokens);
641 	mutex_unlock(&smbios_mutex);
642 }
643 
644 module_init(dell_smbios_init);
645 module_exit(dell_smbios_exit);
646 
647 MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
648 MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@gmail.com>");
649 MODULE_AUTHOR("Pali Rohár <pali@kernel.org>");
650 MODULE_AUTHOR("Mario Limonciello <mario.limonciello@outlook.com>");
651 MODULE_DESCRIPTION("Common functions for kernel modules using Dell SMBIOS");
652 MODULE_LICENSE("GPL");
653