1/*
2 * dmi-sysfs.c
3 *
4 * This module exports the DMI tables read-only to userspace through the
5 * sysfs file system.
6 *
7 * Data is currently found below
8 *    /sys/firmware/dmi/...
9 *
10 * DMI attributes are presented in attribute files with names
11 * formatted using %d-%d, so that the first integer indicates the
12 * structure type (0-255), and the second field is the instance of that
13 * entry.
14 *
15 * Copyright 2011 Google, Inc.
16 */
17
18#include <linux/kernel.h>
19#include <linux/init.h>
20#include <linux/module.h>
21#include <linux/types.h>
22#include <linux/kobject.h>
23#include <linux/dmi.h>
24#include <linux/capability.h>
25#include <linux/slab.h>
26#include <linux/list.h>
27#include <linux/io.h>
28
29#define MAX_ENTRY_TYPE 255 /* Most of these aren't used, but we consider
30			      the top entry type is only 8 bits */
31
32struct dmi_sysfs_entry {
33	struct dmi_header dh;
34	struct kobject kobj;
35	int instance;
36	int position;
37	struct list_head list;
38	struct kobject *child;
39};
40
41/*
42 * Global list of dmi_sysfs_entry.  Even though this should only be
43 * manipulated at setup and teardown, the lazy nature of the kobject
44 * system means we get lazy removes.
45 */
46static LIST_HEAD(entry_list);
47static DEFINE_SPINLOCK(entry_list_lock);
48
49/* dmi_sysfs_attribute - Top level attribute. used by all entries. */
50struct dmi_sysfs_attribute {
51	struct attribute attr;
52	ssize_t (*show)(struct dmi_sysfs_entry *entry, char *buf);
53};
54
55#define DMI_SYSFS_ATTR(_entry, _name) \
56struct dmi_sysfs_attribute dmi_sysfs_attr_##_entry##_##_name = { \
57	.attr = {.name = __stringify(_name), .mode = 0400}, \
58	.show = dmi_sysfs_##_entry##_##_name, \
59}
60
61/*
62 * dmi_sysfs_mapped_attribute - Attribute where we require the entry be
63 * mapped in.  Use in conjunction with dmi_sysfs_specialize_attr_ops.
64 */
65struct dmi_sysfs_mapped_attribute {
66	struct attribute attr;
67	ssize_t (*show)(struct dmi_sysfs_entry *entry,
68			const struct dmi_header *dh,
69			char *buf);
70};
71
72#define DMI_SYSFS_MAPPED_ATTR(_entry, _name) \
73struct dmi_sysfs_mapped_attribute dmi_sysfs_attr_##_entry##_##_name = { \
74	.attr = {.name = __stringify(_name), .mode = 0400}, \
75	.show = dmi_sysfs_##_entry##_##_name, \
76}
77
78/*************************************************
79 * Generic DMI entry support.
80 *************************************************/
81static void dmi_entry_free(struct kobject *kobj)
82{
83	kfree(kobj);
84}
85
86static struct dmi_sysfs_entry *to_entry(struct kobject *kobj)
87{
88	return container_of(kobj, struct dmi_sysfs_entry, kobj);
89}
90
91static struct dmi_sysfs_attribute *to_attr(struct attribute *attr)
92{
93	return container_of(attr, struct dmi_sysfs_attribute, attr);
94}
95
96static ssize_t dmi_sysfs_attr_show(struct kobject *kobj,
97				   struct attribute *_attr, char *buf)
98{
99	struct dmi_sysfs_entry *entry = to_entry(kobj);
100	struct dmi_sysfs_attribute *attr = to_attr(_attr);
101
102	/* DMI stuff is only ever admin visible */
103	if (!capable(CAP_SYS_ADMIN))
104		return -EACCES;
105
106	return attr->show(entry, buf);
107}
108
109static const struct sysfs_ops dmi_sysfs_attr_ops = {
110	.show = dmi_sysfs_attr_show,
111};
112
113typedef ssize_t (*dmi_callback)(struct dmi_sysfs_entry *,
114				const struct dmi_header *dh, void *);
115
116struct find_dmi_data {
117	struct dmi_sysfs_entry	*entry;
118	dmi_callback		callback;
119	void			*private;
120	int			instance_countdown;
121	ssize_t			ret;
122};
123
124static void find_dmi_entry_helper(const struct dmi_header *dh,
125				  void *_data)
126{
127	struct find_dmi_data *data = _data;
128	struct dmi_sysfs_entry *entry = data->entry;
129
130	/* Is this the entry we want? */
131	if (dh->type != entry->dh.type)
132		return;
133
134	if (data->instance_countdown != 0) {
135		/* try the next instance? */
136		data->instance_countdown--;
137		return;
138	}
139
140	/*
141	 * Don't ever revisit the instance.  Short circuit later
142	 * instances by letting the instance_countdown run negative
143	 */
144	data->instance_countdown--;
145
146	/* Found the entry */
147	data->ret = data->callback(entry, dh, data->private);
148}
149
150/* State for passing the read parameters through dmi_find_entry() */
151struct dmi_read_state {
152	char *buf;
153	loff_t pos;
154	size_t count;
155};
156
157static ssize_t find_dmi_entry(struct dmi_sysfs_entry *entry,
158			      dmi_callback callback, void *private)
159{
160	struct find_dmi_data data = {
161		.entry = entry,
162		.callback = callback,
163		.private = private,
164		.instance_countdown = entry->instance,
165		.ret = -EIO,  /* To signal the entry disappeared */
166	};
167	int ret;
168
169	ret = dmi_walk(find_dmi_entry_helper, &data);
170	/* This shouldn't happen, but just in case. */
171	if (ret)
172		return -EINVAL;
173	return data.ret;
174}
175
176/*
177 * Calculate and return the byte length of the dmi entry identified by
178 * dh.  This includes both the formatted portion as well as the
179 * unformatted string space, including the two trailing nul characters.
180 */
181static size_t dmi_entry_length(const struct dmi_header *dh)
182{
183	const char *p = (const char *)dh;
184
185	p += dh->length;
186
187	while (p[0] || p[1])
188		p++;
189
190	return 2 + p - (const char *)dh;
191}
192
193/*************************************************
194 * Support bits for specialized DMI entry support
195 *************************************************/
196struct dmi_entry_attr_show_data {
197	struct attribute *attr;
198	char *buf;
199};
200
201static ssize_t dmi_entry_attr_show_helper(struct dmi_sysfs_entry *entry,
202					  const struct dmi_header *dh,
203					  void *_data)
204{
205	struct dmi_entry_attr_show_data *data = _data;
206	struct dmi_sysfs_mapped_attribute *attr;
207
208	attr = container_of(data->attr,
209			    struct dmi_sysfs_mapped_attribute, attr);
210	return attr->show(entry, dh, data->buf);
211}
212
213static ssize_t dmi_entry_attr_show(struct kobject *kobj,
214				   struct attribute *attr,
215				   char *buf)
216{
217	struct dmi_entry_attr_show_data data = {
218		.attr = attr,
219		.buf  = buf,
220	};
221	/* Find the entry according to our parent and call the
222	 * normalized show method hanging off of the attribute */
223	return find_dmi_entry(to_entry(kobj->parent),
224			      dmi_entry_attr_show_helper, &data);
225}
226
227static const struct sysfs_ops dmi_sysfs_specialize_attr_ops = {
228	.show = dmi_entry_attr_show,
229};
230
231/*************************************************
232 * Specialized DMI entry support.
233 *************************************************/
234
235/*** Type 15 - System Event Table ***/
236
237#define DMI_SEL_ACCESS_METHOD_IO8	0x00
238#define DMI_SEL_ACCESS_METHOD_IO2x8	0x01
239#define DMI_SEL_ACCESS_METHOD_IO16	0x02
240#define DMI_SEL_ACCESS_METHOD_PHYS32	0x03
241#define DMI_SEL_ACCESS_METHOD_GPNV	0x04
242
243struct dmi_system_event_log {
244	struct dmi_header header;
245	u16	area_length;
246	u16	header_start_offset;
247	u16	data_start_offset;
248	u8	access_method;
249	u8	status;
250	u32	change_token;
251	union {
252		struct {
253			u16 index_addr;
254			u16 data_addr;
255		} io;
256		u32	phys_addr32;
257		u16	gpnv_handle;
258		u32	access_method_address;
259	};
260	u8	header_format;
261	u8	type_descriptors_supported_count;
262	u8	per_log_type_descriptor_length;
263	u8	supported_log_type_descriptos[0];
264} __packed;
265
266#define DMI_SYSFS_SEL_FIELD(_field) \
267static ssize_t dmi_sysfs_sel_##_field(struct dmi_sysfs_entry *entry, \
268				      const struct dmi_header *dh, \
269				      char *buf) \
270{ \
271	struct dmi_system_event_log sel; \
272	if (sizeof(sel) > dmi_entry_length(dh)) \
273		return -EIO; \
274	memcpy(&sel, dh, sizeof(sel)); \
275	return sprintf(buf, "%u\n", sel._field); \
276} \
277static DMI_SYSFS_MAPPED_ATTR(sel, _field)
278
279DMI_SYSFS_SEL_FIELD(area_length);
280DMI_SYSFS_SEL_FIELD(header_start_offset);
281DMI_SYSFS_SEL_FIELD(data_start_offset);
282DMI_SYSFS_SEL_FIELD(access_method);
283DMI_SYSFS_SEL_FIELD(status);
284DMI_SYSFS_SEL_FIELD(change_token);
285DMI_SYSFS_SEL_FIELD(access_method_address);
286DMI_SYSFS_SEL_FIELD(header_format);
287DMI_SYSFS_SEL_FIELD(type_descriptors_supported_count);
288DMI_SYSFS_SEL_FIELD(per_log_type_descriptor_length);
289
290static struct attribute *dmi_sysfs_sel_attrs[] = {
291	&dmi_sysfs_attr_sel_area_length.attr,
292	&dmi_sysfs_attr_sel_header_start_offset.attr,
293	&dmi_sysfs_attr_sel_data_start_offset.attr,
294	&dmi_sysfs_attr_sel_access_method.attr,
295	&dmi_sysfs_attr_sel_status.attr,
296	&dmi_sysfs_attr_sel_change_token.attr,
297	&dmi_sysfs_attr_sel_access_method_address.attr,
298	&dmi_sysfs_attr_sel_header_format.attr,
299	&dmi_sysfs_attr_sel_type_descriptors_supported_count.attr,
300	&dmi_sysfs_attr_sel_per_log_type_descriptor_length.attr,
301	NULL,
302};
303
304
305static struct kobj_type dmi_system_event_log_ktype = {
306	.release = dmi_entry_free,
307	.sysfs_ops = &dmi_sysfs_specialize_attr_ops,
308	.default_attrs = dmi_sysfs_sel_attrs,
309};
310
311typedef u8 (*sel_io_reader)(const struct dmi_system_event_log *sel,
312			    loff_t offset);
313
314static DEFINE_MUTEX(io_port_lock);
315
316static u8 read_sel_8bit_indexed_io(const struct dmi_system_event_log *sel,
317				   loff_t offset)
318{
319	u8 ret;
320
321	mutex_lock(&io_port_lock);
322	outb((u8)offset, sel->io.index_addr);
323	ret = inb(sel->io.data_addr);
324	mutex_unlock(&io_port_lock);
325	return ret;
326}
327
328static u8 read_sel_2x8bit_indexed_io(const struct dmi_system_event_log *sel,
329				     loff_t offset)
330{
331	u8 ret;
332
333	mutex_lock(&io_port_lock);
334	outb((u8)offset, sel->io.index_addr);
335	outb((u8)(offset >> 8), sel->io.index_addr + 1);
336	ret = inb(sel->io.data_addr);
337	mutex_unlock(&io_port_lock);
338	return ret;
339}
340
341static u8 read_sel_16bit_indexed_io(const struct dmi_system_event_log *sel,
342				    loff_t offset)
343{
344	u8 ret;
345
346	mutex_lock(&io_port_lock);
347	outw((u16)offset, sel->io.index_addr);
348	ret = inb(sel->io.data_addr);
349	mutex_unlock(&io_port_lock);
350	return ret;
351}
352
353static sel_io_reader sel_io_readers[] = {
354	[DMI_SEL_ACCESS_METHOD_IO8]	= read_sel_8bit_indexed_io,
355	[DMI_SEL_ACCESS_METHOD_IO2x8]	= read_sel_2x8bit_indexed_io,
356	[DMI_SEL_ACCESS_METHOD_IO16]	= read_sel_16bit_indexed_io,
357};
358
359static ssize_t dmi_sel_raw_read_io(struct dmi_sysfs_entry *entry,
360				   const struct dmi_system_event_log *sel,
361				   char *buf, loff_t pos, size_t count)
362{
363	ssize_t wrote = 0;
364
365	sel_io_reader io_reader = sel_io_readers[sel->access_method];
366
367	while (count && pos < sel->area_length) {
368		count--;
369		*(buf++) = io_reader(sel, pos++);
370		wrote++;
371	}
372
373	return wrote;
374}
375
376static ssize_t dmi_sel_raw_read_phys32(struct dmi_sysfs_entry *entry,
377				       const struct dmi_system_event_log *sel,
378				       char *buf, loff_t pos, size_t count)
379{
380	u8 __iomem *mapped;
381	ssize_t wrote = 0;
382
383	mapped = ioremap(sel->access_method_address, sel->area_length);
384	if (!mapped)
385		return -EIO;
386
387	while (count && pos < sel->area_length) {
388		count--;
389		*(buf++) = readb(mapped + pos++);
390		wrote++;
391	}
392
393	iounmap(mapped);
394	return wrote;
395}
396
397static ssize_t dmi_sel_raw_read_helper(struct dmi_sysfs_entry *entry,
398				       const struct dmi_header *dh,
399				       void *_state)
400{
401	struct dmi_read_state *state = _state;
402	struct dmi_system_event_log sel;
403
404	if (sizeof(sel) > dmi_entry_length(dh))
405		return -EIO;
406
407	memcpy(&sel, dh, sizeof(sel));
408
409	switch (sel.access_method) {
410	case DMI_SEL_ACCESS_METHOD_IO8:
411	case DMI_SEL_ACCESS_METHOD_IO2x8:
412	case DMI_SEL_ACCESS_METHOD_IO16:
413		return dmi_sel_raw_read_io(entry, &sel, state->buf,
414					   state->pos, state->count);
415	case DMI_SEL_ACCESS_METHOD_PHYS32:
416		return dmi_sel_raw_read_phys32(entry, &sel, state->buf,
417					       state->pos, state->count);
418	case DMI_SEL_ACCESS_METHOD_GPNV:
419		pr_info("dmi-sysfs: GPNV support missing.\n");
420		return -EIO;
421	default:
422		pr_info("dmi-sysfs: Unknown access method %02x\n",
423			sel.access_method);
424		return -EIO;
425	}
426}
427
428static ssize_t dmi_sel_raw_read(struct file *filp, struct kobject *kobj,
429				struct bin_attribute *bin_attr,
430				char *buf, loff_t pos, size_t count)
431{
432	struct dmi_sysfs_entry *entry = to_entry(kobj->parent);
433	struct dmi_read_state state = {
434		.buf = buf,
435		.pos = pos,
436		.count = count,
437	};
438
439	return find_dmi_entry(entry, dmi_sel_raw_read_helper, &state);
440}
441
442static struct bin_attribute dmi_sel_raw_attr = {
443	.attr = {.name = "raw_event_log", .mode = 0400},
444	.read = dmi_sel_raw_read,
445};
446
447static int dmi_system_event_log(struct dmi_sysfs_entry *entry)
448{
449	int ret;
450
451	entry->child = kzalloc(sizeof(*entry->child), GFP_KERNEL);
452	if (!entry->child)
453		return -ENOMEM;
454	ret = kobject_init_and_add(entry->child,
455				   &dmi_system_event_log_ktype,
456				   &entry->kobj,
457				   "system_event_log");
458	if (ret)
459		goto out_free;
460
461	ret = sysfs_create_bin_file(entry->child, &dmi_sel_raw_attr);
462	if (ret)
463		goto out_del;
464
465	return 0;
466
467out_del:
468	kobject_del(entry->child);
469out_free:
470	kfree(entry->child);
471	return ret;
472}
473
474/*************************************************
475 * Generic DMI entry support.
476 *************************************************/
477
478static ssize_t dmi_sysfs_entry_length(struct dmi_sysfs_entry *entry, char *buf)
479{
480	return sprintf(buf, "%d\n", entry->dh.length);
481}
482
483static ssize_t dmi_sysfs_entry_handle(struct dmi_sysfs_entry *entry, char *buf)
484{
485	return sprintf(buf, "%d\n", entry->dh.handle);
486}
487
488static ssize_t dmi_sysfs_entry_type(struct dmi_sysfs_entry *entry, char *buf)
489{
490	return sprintf(buf, "%d\n", entry->dh.type);
491}
492
493static ssize_t dmi_sysfs_entry_instance(struct dmi_sysfs_entry *entry,
494					char *buf)
495{
496	return sprintf(buf, "%d\n", entry->instance);
497}
498
499static ssize_t dmi_sysfs_entry_position(struct dmi_sysfs_entry *entry,
500					char *buf)
501{
502	return sprintf(buf, "%d\n", entry->position);
503}
504
505static DMI_SYSFS_ATTR(entry, length);
506static DMI_SYSFS_ATTR(entry, handle);
507static DMI_SYSFS_ATTR(entry, type);
508static DMI_SYSFS_ATTR(entry, instance);
509static DMI_SYSFS_ATTR(entry, position);
510
511static struct attribute *dmi_sysfs_entry_attrs[] = {
512	&dmi_sysfs_attr_entry_length.attr,
513	&dmi_sysfs_attr_entry_handle.attr,
514	&dmi_sysfs_attr_entry_type.attr,
515	&dmi_sysfs_attr_entry_instance.attr,
516	&dmi_sysfs_attr_entry_position.attr,
517	NULL,
518};
519
520static ssize_t dmi_entry_raw_read_helper(struct dmi_sysfs_entry *entry,
521					 const struct dmi_header *dh,
522					 void *_state)
523{
524	struct dmi_read_state *state = _state;
525	size_t entry_length;
526
527	entry_length = dmi_entry_length(dh);
528
529	return memory_read_from_buffer(state->buf, state->count,
530				       &state->pos, dh, entry_length);
531}
532
533static ssize_t dmi_entry_raw_read(struct file *filp,
534				  struct kobject *kobj,
535				  struct bin_attribute *bin_attr,
536				  char *buf, loff_t pos, size_t count)
537{
538	struct dmi_sysfs_entry *entry = to_entry(kobj);
539	struct dmi_read_state state = {
540		.buf = buf,
541		.pos = pos,
542		.count = count,
543	};
544
545	return find_dmi_entry(entry, dmi_entry_raw_read_helper, &state);
546}
547
548static const struct bin_attribute dmi_entry_raw_attr = {
549	.attr = {.name = "raw", .mode = 0400},
550	.read = dmi_entry_raw_read,
551};
552
553static void dmi_sysfs_entry_release(struct kobject *kobj)
554{
555	struct dmi_sysfs_entry *entry = to_entry(kobj);
556
557	spin_lock(&entry_list_lock);
558	list_del(&entry->list);
559	spin_unlock(&entry_list_lock);
560	kfree(entry);
561}
562
563static struct kobj_type dmi_sysfs_entry_ktype = {
564	.release = dmi_sysfs_entry_release,
565	.sysfs_ops = &dmi_sysfs_attr_ops,
566	.default_attrs = dmi_sysfs_entry_attrs,
567};
568
569static struct kset *dmi_kset;
570
571/* Global count of all instances seen.  Only for setup */
572static int __initdata instance_counts[MAX_ENTRY_TYPE + 1];
573
574/* Global positional count of all entries seen.  Only for setup */
575static int __initdata position_count;
576
577static void __init dmi_sysfs_register_handle(const struct dmi_header *dh,
578					     void *_ret)
579{
580	struct dmi_sysfs_entry *entry;
581	int *ret = _ret;
582
583	/* If a previous entry saw an error, short circuit */
584	if (*ret)
585		return;
586
587	/* Allocate and register a new entry into the entries set */
588	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
589	if (!entry) {
590		*ret = -ENOMEM;
591		return;
592	}
593
594	/* Set the key */
595	memcpy(&entry->dh, dh, sizeof(*dh));
596	entry->instance = instance_counts[dh->type]++;
597	entry->position = position_count++;
598
599	entry->kobj.kset = dmi_kset;
600	*ret = kobject_init_and_add(&entry->kobj, &dmi_sysfs_entry_ktype, NULL,
601				    "%d-%d", dh->type, entry->instance);
602
603	if (*ret) {
604		kfree(entry);
605		return;
606	}
607
608	/* Thread on the global list for cleanup */
609	spin_lock(&entry_list_lock);
610	list_add_tail(&entry->list, &entry_list);
611	spin_unlock(&entry_list_lock);
612
613	/* Handle specializations by type */
614	switch (dh->type) {
615	case DMI_ENTRY_SYSTEM_EVENT_LOG:
616		*ret = dmi_system_event_log(entry);
617		break;
618	default:
619		/* No specialization */
620		break;
621	}
622	if (*ret)
623		goto out_err;
624
625	/* Create the raw binary file to access the entry */
626	*ret = sysfs_create_bin_file(&entry->kobj, &dmi_entry_raw_attr);
627	if (*ret)
628		goto out_err;
629
630	return;
631out_err:
632	kobject_put(entry->child);
633	kobject_put(&entry->kobj);
634	return;
635}
636
637static void cleanup_entry_list(void)
638{
639	struct dmi_sysfs_entry *entry, *next;
640
641	/* No locks, we are on our way out */
642	list_for_each_entry_safe(entry, next, &entry_list, list) {
643		kobject_put(entry->child);
644		kobject_put(&entry->kobj);
645	}
646}
647
648static int __init dmi_sysfs_init(void)
649{
650	int error;
651	int val;
652
653	if (!dmi_kobj) {
654		pr_err("dmi-sysfs: dmi entry is absent.\n");
655		error = -ENODATA;
656		goto err;
657	}
658
659	dmi_kset = kset_create_and_add("entries", NULL, dmi_kobj);
660	if (!dmi_kset) {
661		error = -ENOMEM;
662		goto err;
663	}
664
665	val = 0;
666	error = dmi_walk(dmi_sysfs_register_handle, &val);
667	if (error)
668		goto err;
669	if (val) {
670		error = val;
671		goto err;
672	}
673
674	pr_debug("dmi-sysfs: loaded.\n");
675
676	return 0;
677err:
678	cleanup_entry_list();
679	kset_unregister(dmi_kset);
680	return error;
681}
682
683/* clean up everything. */
684static void __exit dmi_sysfs_exit(void)
685{
686	pr_debug("dmi-sysfs: unloading.\n");
687	cleanup_entry_list();
688	kset_unregister(dmi_kset);
689}
690
691module_init(dmi_sysfs_init);
692module_exit(dmi_sysfs_exit);
693
694MODULE_AUTHOR("Mike Waychison <mikew@google.com>");
695MODULE_DESCRIPTION("DMI sysfs support");
696MODULE_LICENSE("GPL");
697