1 /*
2  *  Common functions for kernel modules using Dell SMBIOS
3  *
4  *  Copyright (c) Red Hat <mjg@redhat.com>
5  *  Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>
6  *  Copyright (c) 2014 Pali Rohár <pali.rohar@gmail.com>
7  *
8  *  Based on documentation in the libsmbios package:
9  *  Copyright (C) 2005-2014 Dell Inc.
10  *
11  *  This program is free software; you can redistribute it and/or modify
12  *  it under the terms of the GNU General Public License version 2 as
13  *  published by the Free Software Foundation.
14  */
15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16 
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/capability.h>
20 #include <linux/dmi.h>
21 #include <linux/err.h>
22 #include <linux/mutex.h>
23 #include <linux/platform_device.h>
24 #include <linux/slab.h>
25 #include "dell-smbios.h"
26 
27 static u32 da_supported_commands;
28 static int da_num_tokens;
29 static struct platform_device *platform_device;
30 static struct calling_interface_token *da_tokens;
31 static struct device_attribute *token_location_attrs;
32 static struct device_attribute *token_value_attrs;
33 static struct attribute **token_attrs;
34 static DEFINE_MUTEX(smbios_mutex);
35 
36 struct smbios_device {
37 	struct list_head list;
38 	struct device *device;
39 	int (*call_fn)(struct calling_interface_buffer *arg);
40 };
41 
42 struct smbios_call {
43 	u32 need_capability;
44 	int cmd_class;
45 	int cmd_select;
46 };
47 
48 /* calls that are whitelisted for given capabilities */
49 static struct smbios_call call_whitelist[] = {
50 	/* generally tokens are allowed, but may be further filtered or
51 	 * restricted by token blacklist or whitelist
52 	 */
53 	{CAP_SYS_ADMIN,	CLASS_TOKEN_READ,	SELECT_TOKEN_STD},
54 	{CAP_SYS_ADMIN,	CLASS_TOKEN_READ,	SELECT_TOKEN_AC},
55 	{CAP_SYS_ADMIN,	CLASS_TOKEN_READ,	SELECT_TOKEN_BAT},
56 	{CAP_SYS_ADMIN,	CLASS_TOKEN_WRITE,	SELECT_TOKEN_STD},
57 	{CAP_SYS_ADMIN,	CLASS_TOKEN_WRITE,	SELECT_TOKEN_AC},
58 	{CAP_SYS_ADMIN,	CLASS_TOKEN_WRITE,	SELECT_TOKEN_BAT},
59 	/* used by userspace: fwupdate */
60 	{CAP_SYS_ADMIN, CLASS_ADMIN_PROP,	SELECT_ADMIN_PROP},
61 	/* used by userspace: fwupd */
62 	{CAP_SYS_ADMIN,	CLASS_INFO,		SELECT_DOCK},
63 	{CAP_SYS_ADMIN,	CLASS_FLASH_INTERFACE,	SELECT_FLASH_INTERFACE},
64 };
65 
66 /* calls that are explicitly blacklisted */
67 static struct smbios_call call_blacklist[] = {
68 	{0x0000,  1,  7}, /* manufacturing use */
69 	{0x0000,  6,  5}, /* manufacturing use */
70 	{0x0000, 11,  3}, /* write once */
71 	{0x0000, 11,  7}, /* write once */
72 	{0x0000, 11, 11}, /* write once */
73 	{0x0000, 19, -1}, /* diagnostics */
74 	/* handled by kernel: dell-laptop */
75 	{0x0000, CLASS_INFO, SELECT_RFKILL},
76 	{0x0000, CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT},
77 };
78 
79 struct token_range {
80 	u32 need_capability;
81 	u16 min;
82 	u16 max;
83 };
84 
85 /* tokens that are whitelisted for given capabilities */
86 static struct token_range token_whitelist[] = {
87 	/* used by userspace: fwupdate */
88 	{CAP_SYS_ADMIN,	CAPSULE_EN_TOKEN,	CAPSULE_DIS_TOKEN},
89 	/* can indicate to userspace that WMI is needed */
90 	{0x0000,	WSMT_EN_TOKEN,		WSMT_DIS_TOKEN}
91 };
92 
93 /* tokens that are explicitly blacklisted */
94 static struct token_range token_blacklist[] = {
95 	{0x0000, 0x0058, 0x0059}, /* ME use */
96 	{0x0000, 0x00CD, 0x00D0}, /* raid shadow copy */
97 	{0x0000, 0x013A, 0x01FF}, /* sata shadow copy */
98 	{0x0000, 0x0175, 0x0176}, /* write once */
99 	{0x0000, 0x0195, 0x0197}, /* diagnostics */
100 	{0x0000, 0x01DC, 0x01DD}, /* manufacturing use */
101 	{0x0000, 0x027D, 0x0284}, /* diagnostics */
102 	{0x0000, 0x02E3, 0x02E3}, /* manufacturing use */
103 	{0x0000, 0x02FF, 0x02FF}, /* manufacturing use */
104 	{0x0000, 0x0300, 0x0302}, /* manufacturing use */
105 	{0x0000, 0x0325, 0x0326}, /* manufacturing use */
106 	{0x0000, 0x0332, 0x0335}, /* fan control */
107 	{0x0000, 0x0350, 0x0350}, /* manufacturing use */
108 	{0x0000, 0x0363, 0x0363}, /* manufacturing use */
109 	{0x0000, 0x0368, 0x0368}, /* manufacturing use */
110 	{0x0000, 0x03F6, 0x03F7}, /* manufacturing use */
111 	{0x0000, 0x049E, 0x049F}, /* manufacturing use */
112 	{0x0000, 0x04A0, 0x04A3}, /* disagnostics */
113 	{0x0000, 0x04E6, 0x04E7}, /* manufacturing use */
114 	{0x0000, 0x4000, 0x7FFF}, /* internal BIOS use */
115 	{0x0000, 0x9000, 0x9001}, /* internal BIOS use */
116 	{0x0000, 0xA000, 0xBFFF}, /* write only */
117 	{0x0000, 0xEFF0, 0xEFFF}, /* internal BIOS use */
118 	/* handled by kernel: dell-laptop */
119 	{0x0000, BRIGHTNESS_TOKEN,	BRIGHTNESS_TOKEN},
120 	{0x0000, KBD_LED_OFF_TOKEN,	KBD_LED_AUTO_TOKEN},
121 	{0x0000, KBD_LED_AC_TOKEN,	KBD_LED_AC_TOKEN},
122 	{0x0000, KBD_LED_AUTO_25_TOKEN,	KBD_LED_AUTO_75_TOKEN},
123 	{0x0000, KBD_LED_AUTO_100_TOKEN,	KBD_LED_AUTO_100_TOKEN},
124 	{0x0000, GLOBAL_MIC_MUTE_ENABLE,	GLOBAL_MIC_MUTE_DISABLE},
125 };
126 
127 static LIST_HEAD(smbios_device_list);
128 
dell_smbios_error(int value)129 int dell_smbios_error(int value)
130 {
131 	switch (value) {
132 	case 0: /* Completed successfully */
133 		return 0;
134 	case -1: /* Completed with error */
135 		return -EIO;
136 	case -2: /* Function not supported */
137 		return -ENXIO;
138 	default: /* Unknown error */
139 		return -EINVAL;
140 	}
141 }
142 EXPORT_SYMBOL_GPL(dell_smbios_error);
143 
dell_smbios_register_device(struct device * d,void * call_fn)144 int dell_smbios_register_device(struct device *d, void *call_fn)
145 {
146 	struct smbios_device *priv;
147 
148 	priv = devm_kzalloc(d, sizeof(struct smbios_device), GFP_KERNEL);
149 	if (!priv)
150 		return -ENOMEM;
151 	get_device(d);
152 	priv->device = d;
153 	priv->call_fn = call_fn;
154 	mutex_lock(&smbios_mutex);
155 	list_add_tail(&priv->list, &smbios_device_list);
156 	mutex_unlock(&smbios_mutex);
157 	dev_dbg(d, "Added device: %s\n", d->driver->name);
158 	return 0;
159 }
160 EXPORT_SYMBOL_GPL(dell_smbios_register_device);
161 
dell_smbios_unregister_device(struct device * d)162 void dell_smbios_unregister_device(struct device *d)
163 {
164 	struct smbios_device *priv;
165 
166 	mutex_lock(&smbios_mutex);
167 	list_for_each_entry(priv, &smbios_device_list, list) {
168 		if (priv->device == d) {
169 			list_del(&priv->list);
170 			put_device(d);
171 			break;
172 		}
173 	}
174 	mutex_unlock(&smbios_mutex);
175 	dev_dbg(d, "Remove device: %s\n", d->driver->name);
176 }
177 EXPORT_SYMBOL_GPL(dell_smbios_unregister_device);
178 
dell_smbios_call_filter(struct device * d,struct calling_interface_buffer * buffer)179 int dell_smbios_call_filter(struct device *d,
180 			    struct calling_interface_buffer *buffer)
181 {
182 	u16 t = 0;
183 	int i;
184 
185 	/* can't make calls over 30 */
186 	if (buffer->cmd_class > 30) {
187 		dev_dbg(d, "class too big: %u\n", buffer->cmd_class);
188 		return -EINVAL;
189 	}
190 
191 	/* supported calls on the particular system */
192 	if (!(da_supported_commands & (1 << buffer->cmd_class))) {
193 		dev_dbg(d, "invalid command, supported commands: 0x%8x\n",
194 			da_supported_commands);
195 		return -EINVAL;
196 	}
197 
198 	/* match against call blacklist  */
199 	for (i = 0; i < ARRAY_SIZE(call_blacklist); i++) {
200 		if (buffer->cmd_class != call_blacklist[i].cmd_class)
201 			continue;
202 		if (buffer->cmd_select != call_blacklist[i].cmd_select &&
203 		    call_blacklist[i].cmd_select != -1)
204 			continue;
205 		dev_dbg(d, "blacklisted command: %u/%u\n",
206 			buffer->cmd_class, buffer->cmd_select);
207 		return -EINVAL;
208 	}
209 
210 	/* if a token call, find token ID */
211 
212 	if ((buffer->cmd_class == CLASS_TOKEN_READ ||
213 	     buffer->cmd_class == CLASS_TOKEN_WRITE) &&
214 	     buffer->cmd_select < 3) {
215 		/* tokens enabled ? */
216 		if (!da_tokens) {
217 			dev_dbg(d, "no token support on this system\n");
218 			return -EINVAL;
219 		}
220 
221 		/* find the matching token ID */
222 		for (i = 0; i < da_num_tokens; i++) {
223 			if (da_tokens[i].location != buffer->input[0])
224 				continue;
225 			t = da_tokens[i].tokenID;
226 			break;
227 		}
228 
229 		/* token call; but token didn't exist */
230 		if (!t) {
231 			dev_dbg(d, "token at location %04x doesn't exist\n",
232 				buffer->input[0]);
233 			return -EINVAL;
234 		}
235 
236 		/* match against token blacklist */
237 		for (i = 0; i < ARRAY_SIZE(token_blacklist); i++) {
238 			if (!token_blacklist[i].min || !token_blacklist[i].max)
239 				continue;
240 			if (t >= token_blacklist[i].min &&
241 			    t <= token_blacklist[i].max)
242 				return -EINVAL;
243 		}
244 
245 		/* match against token whitelist */
246 		for (i = 0; i < ARRAY_SIZE(token_whitelist); i++) {
247 			if (!token_whitelist[i].min || !token_whitelist[i].max)
248 				continue;
249 			if (t < token_whitelist[i].min ||
250 			    t > token_whitelist[i].max)
251 				continue;
252 			if (!token_whitelist[i].need_capability ||
253 			    capable(token_whitelist[i].need_capability)) {
254 				dev_dbg(d, "whitelisted token: %x\n", t);
255 				return 0;
256 			}
257 
258 		}
259 	}
260 	/* match against call whitelist */
261 	for (i = 0; i < ARRAY_SIZE(call_whitelist); i++) {
262 		if (buffer->cmd_class != call_whitelist[i].cmd_class)
263 			continue;
264 		if (buffer->cmd_select != call_whitelist[i].cmd_select)
265 			continue;
266 		if (!call_whitelist[i].need_capability ||
267 		    capable(call_whitelist[i].need_capability)) {
268 			dev_dbg(d, "whitelisted capable command: %u/%u\n",
269 			buffer->cmd_class, buffer->cmd_select);
270 			return 0;
271 		}
272 		dev_dbg(d, "missing capability %d for %u/%u\n",
273 			call_whitelist[i].need_capability,
274 			buffer->cmd_class, buffer->cmd_select);
275 
276 	}
277 
278 	/* not in a whitelist, only allow processes with capabilities */
279 	if (capable(CAP_SYS_RAWIO)) {
280 		dev_dbg(d, "Allowing %u/%u due to CAP_SYS_RAWIO\n",
281 			buffer->cmd_class, buffer->cmd_select);
282 		return 0;
283 	}
284 
285 	return -EACCES;
286 }
287 EXPORT_SYMBOL_GPL(dell_smbios_call_filter);
288 
dell_smbios_call(struct calling_interface_buffer * buffer)289 int dell_smbios_call(struct calling_interface_buffer *buffer)
290 {
291 	int (*call_fn)(struct calling_interface_buffer *) = NULL;
292 	struct device *selected_dev = NULL;
293 	struct smbios_device *priv;
294 	int ret;
295 
296 	mutex_lock(&smbios_mutex);
297 	list_for_each_entry(priv, &smbios_device_list, list) {
298 		if (!selected_dev || priv->device->id >= selected_dev->id) {
299 			dev_dbg(priv->device, "Trying device ID: %d\n",
300 				priv->device->id);
301 			call_fn = priv->call_fn;
302 			selected_dev = priv->device;
303 		}
304 	}
305 
306 	if (!selected_dev) {
307 		ret = -ENODEV;
308 		pr_err("No dell-smbios drivers are loaded\n");
309 		goto out_smbios_call;
310 	}
311 
312 	ret = call_fn(buffer);
313 
314 out_smbios_call:
315 	mutex_unlock(&smbios_mutex);
316 	return ret;
317 }
318 EXPORT_SYMBOL_GPL(dell_smbios_call);
319 
dell_smbios_find_token(int tokenid)320 struct calling_interface_token *dell_smbios_find_token(int tokenid)
321 {
322 	int i;
323 
324 	if (!da_tokens)
325 		return NULL;
326 
327 	for (i = 0; i < da_num_tokens; i++) {
328 		if (da_tokens[i].tokenID == tokenid)
329 			return &da_tokens[i];
330 	}
331 
332 	return NULL;
333 }
334 EXPORT_SYMBOL_GPL(dell_smbios_find_token);
335 
336 static BLOCKING_NOTIFIER_HEAD(dell_laptop_chain_head);
337 
dell_laptop_register_notifier(struct notifier_block * nb)338 int dell_laptop_register_notifier(struct notifier_block *nb)
339 {
340 	return blocking_notifier_chain_register(&dell_laptop_chain_head, nb);
341 }
342 EXPORT_SYMBOL_GPL(dell_laptop_register_notifier);
343 
dell_laptop_unregister_notifier(struct notifier_block * nb)344 int dell_laptop_unregister_notifier(struct notifier_block *nb)
345 {
346 	return blocking_notifier_chain_unregister(&dell_laptop_chain_head, nb);
347 }
348 EXPORT_SYMBOL_GPL(dell_laptop_unregister_notifier);
349 
dell_laptop_call_notifier(unsigned long action,void * data)350 void dell_laptop_call_notifier(unsigned long action, void *data)
351 {
352 	blocking_notifier_call_chain(&dell_laptop_chain_head, action, data);
353 }
354 EXPORT_SYMBOL_GPL(dell_laptop_call_notifier);
355 
parse_da_table(const struct dmi_header * dm)356 static void __init parse_da_table(const struct dmi_header *dm)
357 {
358 	/* Final token is a terminator, so we don't want to copy it */
359 	int tokens = (dm->length-11)/sizeof(struct calling_interface_token)-1;
360 	struct calling_interface_token *new_da_tokens;
361 	struct calling_interface_structure *table =
362 		container_of(dm, struct calling_interface_structure, header);
363 
364 	/*
365 	 * 4 bytes of table header, plus 7 bytes of Dell header
366 	 * plus at least 6 bytes of entry
367 	 */
368 
369 	if (dm->length < 17)
370 		return;
371 
372 	da_supported_commands = table->supportedCmds;
373 
374 	new_da_tokens = krealloc(da_tokens, (da_num_tokens + tokens) *
375 				 sizeof(struct calling_interface_token),
376 				 GFP_KERNEL);
377 
378 	if (!new_da_tokens)
379 		return;
380 	da_tokens = new_da_tokens;
381 
382 	memcpy(da_tokens+da_num_tokens, table->tokens,
383 	       sizeof(struct calling_interface_token) * tokens);
384 
385 	da_num_tokens += tokens;
386 }
387 
zero_duplicates(struct device * dev)388 static void zero_duplicates(struct device *dev)
389 {
390 	int i, j;
391 
392 	for (i = 0; i < da_num_tokens; i++) {
393 		if (da_tokens[i].tokenID == 0)
394 			continue;
395 		for (j = i+1; j < da_num_tokens; j++) {
396 			if (da_tokens[j].tokenID == 0)
397 				continue;
398 			if (da_tokens[i].tokenID == da_tokens[j].tokenID) {
399 				dev_dbg(dev, "Zeroing dup token ID %x(%x/%x)\n",
400 					da_tokens[j].tokenID,
401 					da_tokens[j].location,
402 					da_tokens[j].value);
403 				da_tokens[j].tokenID = 0;
404 			}
405 		}
406 	}
407 }
408 
find_tokens(const struct dmi_header * dm,void * dummy)409 static void __init find_tokens(const struct dmi_header *dm, void *dummy)
410 {
411 	switch (dm->type) {
412 	case 0xd4: /* Indexed IO */
413 	case 0xd5: /* Protected Area Type 1 */
414 	case 0xd6: /* Protected Area Type 2 */
415 		break;
416 	case 0xda: /* Calling interface */
417 		parse_da_table(dm);
418 		break;
419 	}
420 }
421 
match_attribute(struct device * dev,struct device_attribute * attr)422 static int match_attribute(struct device *dev,
423 			   struct device_attribute *attr)
424 {
425 	int i;
426 
427 	for (i = 0; i < da_num_tokens * 2; i++) {
428 		if (!token_attrs[i])
429 			continue;
430 		if (strcmp(token_attrs[i]->name, attr->attr.name) == 0)
431 			return i/2;
432 	}
433 	dev_dbg(dev, "couldn't match: %s\n", attr->attr.name);
434 	return -EINVAL;
435 }
436 
location_show(struct device * dev,struct device_attribute * attr,char * buf)437 static ssize_t location_show(struct device *dev,
438 			     struct device_attribute *attr, char *buf)
439 {
440 	int i;
441 
442 	if (!capable(CAP_SYS_ADMIN))
443 		return -EPERM;
444 
445 	i = match_attribute(dev, attr);
446 	if (i > 0)
447 		return scnprintf(buf, PAGE_SIZE, "%08x", da_tokens[i].location);
448 	return 0;
449 }
450 
value_show(struct device * dev,struct device_attribute * attr,char * buf)451 static ssize_t value_show(struct device *dev,
452 			  struct device_attribute *attr, char *buf)
453 {
454 	int i;
455 
456 	if (!capable(CAP_SYS_ADMIN))
457 		return -EPERM;
458 
459 	i = match_attribute(dev, attr);
460 	if (i > 0)
461 		return scnprintf(buf, PAGE_SIZE, "%08x", da_tokens[i].value);
462 	return 0;
463 }
464 
465 static struct attribute_group smbios_attribute_group = {
466 	.name = "tokens"
467 };
468 
469 static struct platform_driver platform_driver = {
470 	.driver = {
471 		.name = "dell-smbios",
472 	},
473 };
474 
build_tokens_sysfs(struct platform_device * dev)475 static int build_tokens_sysfs(struct platform_device *dev)
476 {
477 	char *location_name;
478 	char *value_name;
479 	size_t size;
480 	int ret;
481 	int i, j;
482 
483 	/* (number of tokens  + 1 for null terminated */
484 	size = sizeof(struct device_attribute) * (da_num_tokens + 1);
485 	token_location_attrs = kzalloc(size, GFP_KERNEL);
486 	if (!token_location_attrs)
487 		return -ENOMEM;
488 	token_value_attrs = kzalloc(size, GFP_KERNEL);
489 	if (!token_value_attrs)
490 		goto out_allocate_value;
491 
492 	/* need to store both location and value + terminator*/
493 	size = sizeof(struct attribute *) * ((2 * da_num_tokens) + 1);
494 	token_attrs = kzalloc(size, GFP_KERNEL);
495 	if (!token_attrs)
496 		goto out_allocate_attrs;
497 
498 	for (i = 0, j = 0; i < da_num_tokens; i++) {
499 		/* skip empty */
500 		if (da_tokens[i].tokenID == 0)
501 			continue;
502 		/* add location */
503 		location_name = kasprintf(GFP_KERNEL, "%04x_location",
504 					  da_tokens[i].tokenID);
505 		if (location_name == NULL)
506 			goto out_unwind_strings;
507 		sysfs_attr_init(&token_location_attrs[i].attr);
508 		token_location_attrs[i].attr.name = location_name;
509 		token_location_attrs[i].attr.mode = 0444;
510 		token_location_attrs[i].show = location_show;
511 		token_attrs[j++] = &token_location_attrs[i].attr;
512 
513 		/* add value */
514 		value_name = kasprintf(GFP_KERNEL, "%04x_value",
515 				       da_tokens[i].tokenID);
516 		if (value_name == NULL)
517 			goto loop_fail_create_value;
518 		sysfs_attr_init(&token_value_attrs[i].attr);
519 		token_value_attrs[i].attr.name = value_name;
520 		token_value_attrs[i].attr.mode = 0444;
521 		token_value_attrs[i].show = value_show;
522 		token_attrs[j++] = &token_value_attrs[i].attr;
523 		continue;
524 
525 loop_fail_create_value:
526 		kfree(location_name);
527 		goto out_unwind_strings;
528 	}
529 	smbios_attribute_group.attrs = token_attrs;
530 
531 	ret = sysfs_create_group(&dev->dev.kobj, &smbios_attribute_group);
532 	if (ret)
533 		goto out_unwind_strings;
534 	return 0;
535 
536 out_unwind_strings:
537 	while (i--) {
538 		kfree(token_location_attrs[i].attr.name);
539 		kfree(token_value_attrs[i].attr.name);
540 	}
541 	kfree(token_attrs);
542 out_allocate_attrs:
543 	kfree(token_value_attrs);
544 out_allocate_value:
545 	kfree(token_location_attrs);
546 
547 	return -ENOMEM;
548 }
549 
free_group(struct platform_device * pdev)550 static void free_group(struct platform_device *pdev)
551 {
552 	int i;
553 
554 	sysfs_remove_group(&pdev->dev.kobj,
555 				&smbios_attribute_group);
556 	for (i = 0; i < da_num_tokens; i++) {
557 		kfree(token_location_attrs[i].attr.name);
558 		kfree(token_value_attrs[i].attr.name);
559 	}
560 	kfree(token_attrs);
561 	kfree(token_value_attrs);
562 	kfree(token_location_attrs);
563 }
564 
dell_smbios_init(void)565 static int __init dell_smbios_init(void)
566 {
567 	int ret, wmi, smm;
568 
569 	if (!dmi_find_device(DMI_DEV_TYPE_OEM_STRING, "Dell System", NULL) &&
570 	    !dmi_find_device(DMI_DEV_TYPE_OEM_STRING, "www.dell.com", NULL)) {
571 		pr_err("Unable to run on non-Dell system\n");
572 		return -ENODEV;
573 	}
574 
575 	dmi_walk(find_tokens, NULL);
576 
577 	ret = platform_driver_register(&platform_driver);
578 	if (ret)
579 		goto fail_platform_driver;
580 
581 	platform_device = platform_device_alloc("dell-smbios", 0);
582 	if (!platform_device) {
583 		ret = -ENOMEM;
584 		goto fail_platform_device_alloc;
585 	}
586 	ret = platform_device_add(platform_device);
587 	if (ret)
588 		goto fail_platform_device_add;
589 
590 	/* register backends */
591 	wmi = init_dell_smbios_wmi();
592 	if (wmi)
593 		pr_debug("Failed to initialize WMI backend: %d\n", wmi);
594 	smm = init_dell_smbios_smm();
595 	if (smm)
596 		pr_debug("Failed to initialize SMM backend: %d\n", smm);
597 	if (wmi && smm) {
598 		pr_err("No SMBIOS backends available (wmi: %d, smm: %d)\n",
599 			wmi, smm);
600 		goto fail_create_group;
601 	}
602 
603 	if (da_tokens)  {
604 		/* duplicate tokens will cause problems building sysfs files */
605 		zero_duplicates(&platform_device->dev);
606 
607 		ret = build_tokens_sysfs(platform_device);
608 		if (ret)
609 			goto fail_sysfs;
610 	}
611 
612 	return 0;
613 
614 fail_sysfs:
615 	free_group(platform_device);
616 
617 fail_create_group:
618 	platform_device_del(platform_device);
619 
620 fail_platform_device_add:
621 	platform_device_put(platform_device);
622 
623 fail_platform_device_alloc:
624 	platform_driver_unregister(&platform_driver);
625 
626 fail_platform_driver:
627 	kfree(da_tokens);
628 	return ret;
629 }
630 
dell_smbios_exit(void)631 static void __exit dell_smbios_exit(void)
632 {
633 	exit_dell_smbios_wmi();
634 	exit_dell_smbios_smm();
635 	mutex_lock(&smbios_mutex);
636 	if (platform_device) {
637 		if (da_tokens)
638 			free_group(platform_device);
639 		platform_device_unregister(platform_device);
640 		platform_driver_unregister(&platform_driver);
641 	}
642 	kfree(da_tokens);
643 	mutex_unlock(&smbios_mutex);
644 }
645 
646 module_init(dell_smbios_init);
647 module_exit(dell_smbios_exit);
648 
649 MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
650 MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@gmail.com>");
651 MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
652 MODULE_AUTHOR("Mario Limonciello <mario.limonciello@dell.com>");
653 MODULE_DESCRIPTION("Common functions for kernel modules using Dell SMBIOS");
654 MODULE_LICENSE("GPL");
655