1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * dmi-sysfs.c
4 *
5 * This module exports the DMI tables read-only to userspace through the
6 * sysfs file system.
7 *
8 * Data is currently found below
9 * /sys/firmware/dmi/...
10 *
11 * DMI attributes are presented in attribute files with names
12 * formatted using %d-%d, so that the first integer indicates the
13 * structure type (0-255), and the second field is the instance of that
14 * entry.
15 *
16 * Copyright 2011 Google, Inc.
17 */
18
19#include <linux/kernel.h>
20#include <linux/init.h>
21#include <linux/module.h>
22#include <linux/types.h>
23#include <linux/kobject.h>
24#include <linux/dmi.h>
25#include <linux/capability.h>
26#include <linux/slab.h>
27#include <linux/list.h>
28#include <linux/io.h>
29#include <asm/dmi.h>
30
31#define MAX_ENTRY_TYPE 255 /* Most of these aren't used, but we consider
32 the top entry type is only 8 bits */
33
34struct dmi_sysfs_entry {
35 struct dmi_header dh;
36 struct kobject kobj;
37 int instance;
38 int position;
39 struct list_head list;
40 struct kobject *child;
41};
42
43/*
44 * Global list of dmi_sysfs_entry. Even though this should only be
45 * manipulated at setup and teardown, the lazy nature of the kobject
46 * system means we get lazy removes.
47 */
48static LIST_HEAD(entry_list);
49static DEFINE_SPINLOCK(entry_list_lock);
50
51/* dmi_sysfs_attribute - Top level attribute. used by all entries. */
52struct dmi_sysfs_attribute {
53 struct attribute attr;
54 ssize_t (*show)(struct dmi_sysfs_entry *entry, char *buf);
55};
56
57#define DMI_SYSFS_ATTR(_entry, _name) \
58struct dmi_sysfs_attribute dmi_sysfs_attr_##_entry##_##_name = { \
59 .attr = {.name = __stringify(_name), .mode = 0400}, \
60 .show = dmi_sysfs_##_entry##_##_name, \
61}
62
63/*
64 * dmi_sysfs_mapped_attribute - Attribute where we require the entry be
65 * mapped in. Use in conjunction with dmi_sysfs_specialize_attr_ops.
66 */
67struct dmi_sysfs_mapped_attribute {
68 struct attribute attr;
69 ssize_t (*show)(struct dmi_sysfs_entry *entry,
70 const struct dmi_header *dh,
71 char *buf);
72};
73
74#define DMI_SYSFS_MAPPED_ATTR(_entry, _name) \
75struct dmi_sysfs_mapped_attribute dmi_sysfs_attr_##_entry##_##_name = { \
76 .attr = {.name = __stringify(_name), .mode = 0400}, \
77 .show = dmi_sysfs_##_entry##_##_name, \
78}
79
80/*************************************************
81 * Generic DMI entry support.
82 *************************************************/
83static void dmi_entry_free(struct kobject *kobj)
84{
85 kfree(objp: kobj);
86}
87
88static struct dmi_sysfs_entry *to_entry(struct kobject *kobj)
89{
90 return container_of(kobj, struct dmi_sysfs_entry, kobj);
91}
92
93static struct dmi_sysfs_attribute *to_attr(struct attribute *attr)
94{
95 return container_of(attr, struct dmi_sysfs_attribute, attr);
96}
97
98static ssize_t dmi_sysfs_attr_show(struct kobject *kobj,
99 struct attribute *_attr, char *buf)
100{
101 struct dmi_sysfs_entry *entry = to_entry(kobj);
102 struct dmi_sysfs_attribute *attr = to_attr(attr: _attr);
103
104 /* DMI stuff is only ever admin visible */
105 if (!capable(CAP_SYS_ADMIN))
106 return -EACCES;
107
108 return attr->show(entry, buf);
109}
110
111static const struct sysfs_ops dmi_sysfs_attr_ops = {
112 .show = dmi_sysfs_attr_show,
113};
114
115typedef ssize_t (*dmi_callback)(struct dmi_sysfs_entry *,
116 const struct dmi_header *dh, void *);
117
118struct find_dmi_data {
119 struct dmi_sysfs_entry *entry;
120 dmi_callback callback;
121 void *private;
122 int instance_countdown;
123 ssize_t ret;
124};
125
126static void find_dmi_entry_helper(const struct dmi_header *dh,
127 void *_data)
128{
129 struct find_dmi_data *data = _data;
130 struct dmi_sysfs_entry *entry = data->entry;
131
132 /* Is this the entry we want? */
133 if (dh->type != entry->dh.type)
134 return;
135
136 if (data->instance_countdown != 0) {
137 /* try the next instance? */
138 data->instance_countdown--;
139 return;
140 }
141
142 /*
143 * Don't ever revisit the instance. Short circuit later
144 * instances by letting the instance_countdown run negative
145 */
146 data->instance_countdown--;
147
148 /* Found the entry */
149 data->ret = data->callback(entry, dh, data->private);
150}
151
152/* State for passing the read parameters through dmi_find_entry() */
153struct dmi_read_state {
154 char *buf;
155 loff_t pos;
156 size_t count;
157};
158
159static ssize_t find_dmi_entry(struct dmi_sysfs_entry *entry,
160 dmi_callback callback, void *private)
161{
162 struct find_dmi_data data = {
163 .entry = entry,
164 .callback = callback,
165 .private = private,
166 .instance_countdown = entry->instance,
167 .ret = -EIO, /* To signal the entry disappeared */
168 };
169 int ret;
170
171 ret = dmi_walk(decode: find_dmi_entry_helper, private_data: &data);
172 /* This shouldn't happen, but just in case. */
173 if (ret)
174 return -EINVAL;
175 return data.ret;
176}
177
178/*
179 * Calculate and return the byte length of the dmi entry identified by
180 * dh. This includes both the formatted portion as well as the
181 * unformatted string space, including the two trailing nul characters.
182 */
183static size_t dmi_entry_length(const struct dmi_header *dh)
184{
185 const char *p = (const char *)dh;
186
187 p += dh->length;
188
189 while (p[0] || p[1])
190 p++;
191
192 return 2 + p - (const char *)dh;
193}
194
195/*************************************************
196 * Support bits for specialized DMI entry support
197 *************************************************/
198struct dmi_entry_attr_show_data {
199 struct attribute *attr;
200 char *buf;
201};
202
203static ssize_t dmi_entry_attr_show_helper(struct dmi_sysfs_entry *entry,
204 const struct dmi_header *dh,
205 void *_data)
206{
207 struct dmi_entry_attr_show_data *data = _data;
208 struct dmi_sysfs_mapped_attribute *attr;
209
210 attr = container_of(data->attr,
211 struct dmi_sysfs_mapped_attribute, attr);
212 return attr->show(entry, dh, data->buf);
213}
214
215static ssize_t dmi_entry_attr_show(struct kobject *kobj,
216 struct attribute *attr,
217 char *buf)
218{
219 struct dmi_entry_attr_show_data data = {
220 .attr = attr,
221 .buf = buf,
222 };
223 /* Find the entry according to our parent and call the
224 * normalized show method hanging off of the attribute */
225 return find_dmi_entry(entry: to_entry(kobj: kobj->parent),
226 callback: dmi_entry_attr_show_helper, private: &data);
227}
228
229static const struct sysfs_ops dmi_sysfs_specialize_attr_ops = {
230 .show = dmi_entry_attr_show,
231};
232
233/*************************************************
234 * Specialized DMI entry support.
235 *************************************************/
236
237/*** Type 15 - System Event Table ***/
238
239#define DMI_SEL_ACCESS_METHOD_IO8 0x00
240#define DMI_SEL_ACCESS_METHOD_IO2x8 0x01
241#define DMI_SEL_ACCESS_METHOD_IO16 0x02
242#define DMI_SEL_ACCESS_METHOD_PHYS32 0x03
243#define DMI_SEL_ACCESS_METHOD_GPNV 0x04
244
245struct dmi_system_event_log {
246 struct dmi_header header;
247 u16 area_length;
248 u16 header_start_offset;
249 u16 data_start_offset;
250 u8 access_method;
251 u8 status;
252 u32 change_token;
253 union {
254 struct {
255 u16 index_addr;
256 u16 data_addr;
257 } io;
258 u32 phys_addr32;
259 u16 gpnv_handle;
260 u32 access_method_address;
261 };
262 u8 header_format;
263 u8 type_descriptors_supported_count;
264 u8 per_log_type_descriptor_length;
265 u8 supported_log_type_descriptos[];
266} __packed;
267
268#define DMI_SYSFS_SEL_FIELD(_field) \
269static ssize_t dmi_sysfs_sel_##_field(struct dmi_sysfs_entry *entry, \
270 const struct dmi_header *dh, \
271 char *buf) \
272{ \
273 struct dmi_system_event_log sel; \
274 if (sizeof(sel) > dmi_entry_length(dh)) \
275 return -EIO; \
276 memcpy(&sel, dh, sizeof(sel)); \
277 return sprintf(buf, "%u\n", sel._field); \
278} \
279static DMI_SYSFS_MAPPED_ATTR(sel, _field)
280
281DMI_SYSFS_SEL_FIELD(area_length);
282DMI_SYSFS_SEL_FIELD(header_start_offset);
283DMI_SYSFS_SEL_FIELD(data_start_offset);
284DMI_SYSFS_SEL_FIELD(access_method);
285DMI_SYSFS_SEL_FIELD(status);
286DMI_SYSFS_SEL_FIELD(change_token);
287DMI_SYSFS_SEL_FIELD(access_method_address);
288DMI_SYSFS_SEL_FIELD(header_format);
289DMI_SYSFS_SEL_FIELD(type_descriptors_supported_count);
290DMI_SYSFS_SEL_FIELD(per_log_type_descriptor_length);
291
292static struct attribute *dmi_sysfs_sel_attrs[] = {
293 &dmi_sysfs_attr_sel_area_length.attr,
294 &dmi_sysfs_attr_sel_header_start_offset.attr,
295 &dmi_sysfs_attr_sel_data_start_offset.attr,
296 &dmi_sysfs_attr_sel_access_method.attr,
297 &dmi_sysfs_attr_sel_status.attr,
298 &dmi_sysfs_attr_sel_change_token.attr,
299 &dmi_sysfs_attr_sel_access_method_address.attr,
300 &dmi_sysfs_attr_sel_header_format.attr,
301 &dmi_sysfs_attr_sel_type_descriptors_supported_count.attr,
302 &dmi_sysfs_attr_sel_per_log_type_descriptor_length.attr,
303 NULL,
304};
305ATTRIBUTE_GROUPS(dmi_sysfs_sel);
306
307static const struct kobj_type dmi_system_event_log_ktype = {
308 .release = dmi_entry_free,
309 .sysfs_ops = &dmi_sysfs_specialize_attr_ops,
310 .default_groups = dmi_sysfs_sel_groups,
311};
312
313#ifdef CONFIG_HAS_IOPORT
314typedef u8 (*sel_io_reader)(const struct dmi_system_event_log *sel,
315 loff_t offset);
316
317static DEFINE_MUTEX(io_port_lock);
318
319static u8 read_sel_8bit_indexed_io(const struct dmi_system_event_log *sel,
320 loff_t offset)
321{
322 u8 ret;
323
324 mutex_lock(&io_port_lock);
325 outb(value: (u8)offset, port: sel->io.index_addr);
326 ret = inb(port: sel->io.data_addr);
327 mutex_unlock(lock: &io_port_lock);
328 return ret;
329}
330
331static u8 read_sel_2x8bit_indexed_io(const struct dmi_system_event_log *sel,
332 loff_t offset)
333{
334 u8 ret;
335
336 mutex_lock(&io_port_lock);
337 outb(value: (u8)offset, port: sel->io.index_addr);
338 outb(value: (u8)(offset >> 8), port: sel->io.index_addr + 1);
339 ret = inb(port: sel->io.data_addr);
340 mutex_unlock(lock: &io_port_lock);
341 return ret;
342}
343
344static u8 read_sel_16bit_indexed_io(const struct dmi_system_event_log *sel,
345 loff_t offset)
346{
347 u8 ret;
348
349 mutex_lock(&io_port_lock);
350 outw(value: (u16)offset, port: sel->io.index_addr);
351 ret = inb(port: sel->io.data_addr);
352 mutex_unlock(lock: &io_port_lock);
353 return ret;
354}
355
356static sel_io_reader sel_io_readers[] = {
357 [DMI_SEL_ACCESS_METHOD_IO8] = read_sel_8bit_indexed_io,
358 [DMI_SEL_ACCESS_METHOD_IO2x8] = read_sel_2x8bit_indexed_io,
359 [DMI_SEL_ACCESS_METHOD_IO16] = read_sel_16bit_indexed_io,
360};
361
362static ssize_t dmi_sel_raw_read_io(struct dmi_sysfs_entry *entry,
363 const struct dmi_system_event_log *sel,
364 char *buf, loff_t pos, size_t count)
365{
366 ssize_t wrote = 0;
367
368 sel_io_reader io_reader = sel_io_readers[sel->access_method];
369
370 while (count && pos < sel->area_length) {
371 count--;
372 *(buf++) = io_reader(sel, pos++);
373 wrote++;
374 }
375
376 return wrote;
377}
378#endif
379
380static ssize_t dmi_sel_raw_read_phys32(struct dmi_sysfs_entry *entry,
381 const struct dmi_system_event_log *sel,
382 char *buf, loff_t pos, size_t count)
383{
384 u8 __iomem *mapped;
385 ssize_t wrote = 0;
386
387 mapped = dmi_remap(sel->access_method_address, sel->area_length);
388 if (!mapped)
389 return -EIO;
390
391 while (count && pos < sel->area_length) {
392 count--;
393 *(buf++) = readb(addr: mapped + pos++);
394 wrote++;
395 }
396
397 dmi_unmap(mapped);
398 return wrote;
399}
400
401static ssize_t dmi_sel_raw_read_helper(struct dmi_sysfs_entry *entry,
402 const struct dmi_header *dh,
403 void *_state)
404{
405 struct dmi_read_state *state = _state;
406 struct dmi_system_event_log sel;
407
408 if (sizeof(sel) > dmi_entry_length(dh))
409 return -EIO;
410
411 memcpy(&sel, dh, sizeof(sel));
412
413 switch (sel.access_method) {
414#ifdef CONFIG_HAS_IOPORT
415 case DMI_SEL_ACCESS_METHOD_IO8:
416 case DMI_SEL_ACCESS_METHOD_IO2x8:
417 case DMI_SEL_ACCESS_METHOD_IO16:
418 return dmi_sel_raw_read_io(entry, sel: &sel, buf: state->buf,
419 pos: state->pos, count: state->count);
420#endif
421 case DMI_SEL_ACCESS_METHOD_PHYS32:
422 return dmi_sel_raw_read_phys32(entry, sel: &sel, buf: state->buf,
423 pos: state->pos, count: state->count);
424 case DMI_SEL_ACCESS_METHOD_GPNV:
425 pr_info_ratelimited("dmi-sysfs: GPNV support missing.\n");
426 return -EIO;
427 default:
428 pr_info_ratelimited("dmi-sysfs: Unknown access method %02x\n",
429 sel.access_method);
430 return -EIO;
431 }
432}
433
434static ssize_t dmi_sel_raw_read(struct file *filp, struct kobject *kobj,
435 struct bin_attribute *bin_attr,
436 char *buf, loff_t pos, size_t count)
437{
438 struct dmi_sysfs_entry *entry = to_entry(kobj: kobj->parent);
439 struct dmi_read_state state = {
440 .buf = buf,
441 .pos = pos,
442 .count = count,
443 };
444
445 return find_dmi_entry(entry, callback: dmi_sel_raw_read_helper, private: &state);
446}
447
448static struct bin_attribute dmi_sel_raw_attr = {
449 .attr = {.name = "raw_event_log", .mode = 0400},
450 .read = dmi_sel_raw_read,
451};
452
453static int dmi_system_event_log(struct dmi_sysfs_entry *entry)
454{
455 int ret;
456
457 entry->child = kzalloc(size: sizeof(*entry->child), GFP_KERNEL);
458 if (!entry->child)
459 return -ENOMEM;
460 ret = kobject_init_and_add(kobj: entry->child,
461 ktype: &dmi_system_event_log_ktype,
462 parent: &entry->kobj,
463 fmt: "system_event_log");
464 if (ret)
465 goto out_free;
466
467 ret = sysfs_create_bin_file(kobj: entry->child, attr: &dmi_sel_raw_attr);
468 if (ret)
469 goto out_del;
470
471 return 0;
472
473out_del:
474 kobject_del(kobj: entry->child);
475out_free:
476 kfree(objp: entry->child);
477 return ret;
478}
479
480/*************************************************
481 * Generic DMI entry support.
482 *************************************************/
483
484static ssize_t dmi_sysfs_entry_length(struct dmi_sysfs_entry *entry, char *buf)
485{
486 return sprintf(buf, fmt: "%d\n", entry->dh.length);
487}
488
489static ssize_t dmi_sysfs_entry_handle(struct dmi_sysfs_entry *entry, char *buf)
490{
491 return sprintf(buf, fmt: "%d\n", entry->dh.handle);
492}
493
494static ssize_t dmi_sysfs_entry_type(struct dmi_sysfs_entry *entry, char *buf)
495{
496 return sprintf(buf, fmt: "%d\n", entry->dh.type);
497}
498
499static ssize_t dmi_sysfs_entry_instance(struct dmi_sysfs_entry *entry,
500 char *buf)
501{
502 return sprintf(buf, fmt: "%d\n", entry->instance);
503}
504
505static ssize_t dmi_sysfs_entry_position(struct dmi_sysfs_entry *entry,
506 char *buf)
507{
508 return sprintf(buf, fmt: "%d\n", entry->position);
509}
510
511static DMI_SYSFS_ATTR(entry, length);
512static DMI_SYSFS_ATTR(entry, handle);
513static DMI_SYSFS_ATTR(entry, type);
514static DMI_SYSFS_ATTR(entry, instance);
515static DMI_SYSFS_ATTR(entry, position);
516
517static struct attribute *dmi_sysfs_entry_attrs[] = {
518 &dmi_sysfs_attr_entry_length.attr,
519 &dmi_sysfs_attr_entry_handle.attr,
520 &dmi_sysfs_attr_entry_type.attr,
521 &dmi_sysfs_attr_entry_instance.attr,
522 &dmi_sysfs_attr_entry_position.attr,
523 NULL,
524};
525ATTRIBUTE_GROUPS(dmi_sysfs_entry);
526
527static ssize_t dmi_entry_raw_read_helper(struct dmi_sysfs_entry *entry,
528 const struct dmi_header *dh,
529 void *_state)
530{
531 struct dmi_read_state *state = _state;
532 size_t entry_length;
533
534 entry_length = dmi_entry_length(dh);
535
536 return memory_read_from_buffer(to: state->buf, count: state->count,
537 ppos: &state->pos, from: dh, available: entry_length);
538}
539
540static ssize_t dmi_entry_raw_read(struct file *filp,
541 struct kobject *kobj,
542 struct bin_attribute *bin_attr,
543 char *buf, loff_t pos, size_t count)
544{
545 struct dmi_sysfs_entry *entry = to_entry(kobj);
546 struct dmi_read_state state = {
547 .buf = buf,
548 .pos = pos,
549 .count = count,
550 };
551
552 return find_dmi_entry(entry, callback: dmi_entry_raw_read_helper, private: &state);
553}
554
555static const struct bin_attribute dmi_entry_raw_attr = {
556 .attr = {.name = "raw", .mode = 0400},
557 .read = dmi_entry_raw_read,
558};
559
560static void dmi_sysfs_entry_release(struct kobject *kobj)
561{
562 struct dmi_sysfs_entry *entry = to_entry(kobj);
563
564 spin_lock(lock: &entry_list_lock);
565 list_del(entry: &entry->list);
566 spin_unlock(lock: &entry_list_lock);
567 kfree(objp: entry);
568}
569
570static const struct kobj_type dmi_sysfs_entry_ktype = {
571 .release = dmi_sysfs_entry_release,
572 .sysfs_ops = &dmi_sysfs_attr_ops,
573 .default_groups = dmi_sysfs_entry_groups,
574};
575
576static struct kset *dmi_kset;
577
578/* Global count of all instances seen. Only for setup */
579static int __initdata instance_counts[MAX_ENTRY_TYPE + 1];
580
581/* Global positional count of all entries seen. Only for setup */
582static int __initdata position_count;
583
584static void __init dmi_sysfs_register_handle(const struct dmi_header *dh,
585 void *_ret)
586{
587 struct dmi_sysfs_entry *entry;
588 int *ret = _ret;
589
590 /* If a previous entry saw an error, short circuit */
591 if (*ret)
592 return;
593
594 /* Allocate and register a new entry into the entries set */
595 entry = kzalloc(size: sizeof(*entry), GFP_KERNEL);
596 if (!entry) {
597 *ret = -ENOMEM;
598 return;
599 }
600
601 /* Set the key */
602 memcpy(&entry->dh, dh, sizeof(*dh));
603 entry->instance = instance_counts[dh->type]++;
604 entry->position = position_count++;
605
606 entry->kobj.kset = dmi_kset;
607 *ret = kobject_init_and_add(kobj: &entry->kobj, ktype: &dmi_sysfs_entry_ktype, NULL,
608 fmt: "%d-%d", dh->type, entry->instance);
609
610 /* Thread on the global list for cleanup */
611 spin_lock(lock: &entry_list_lock);
612 list_add_tail(new: &entry->list, head: &entry_list);
613 spin_unlock(lock: &entry_list_lock);
614
615 if (*ret) {
616 kobject_put(kobj: &entry->kobj);
617 return;
618 }
619
620 /* Handle specializations by type */
621 switch (dh->type) {
622 case DMI_ENTRY_SYSTEM_EVENT_LOG:
623 *ret = dmi_system_event_log(entry);
624 break;
625 default:
626 /* No specialization */
627 break;
628 }
629 if (*ret)
630 goto out_err;
631
632 /* Create the raw binary file to access the entry */
633 *ret = sysfs_create_bin_file(kobj: &entry->kobj, attr: &dmi_entry_raw_attr);
634 if (*ret)
635 goto out_err;
636
637 return;
638out_err:
639 kobject_put(kobj: entry->child);
640 kobject_put(kobj: &entry->kobj);
641 return;
642}
643
644static void cleanup_entry_list(void)
645{
646 struct dmi_sysfs_entry *entry, *next;
647
648 /* No locks, we are on our way out */
649 list_for_each_entry_safe(entry, next, &entry_list, list) {
650 kobject_put(kobj: entry->child);
651 kobject_put(kobj: &entry->kobj);
652 }
653}
654
655static int __init dmi_sysfs_init(void)
656{
657 int error;
658 int val;
659
660 if (!dmi_kobj) {
661 pr_debug("dmi-sysfs: dmi entry is absent.\n");
662 error = -ENODATA;
663 goto err;
664 }
665
666 dmi_kset = kset_create_and_add(name: "entries", NULL, parent_kobj: dmi_kobj);
667 if (!dmi_kset) {
668 error = -ENOMEM;
669 goto err;
670 }
671
672 val = 0;
673 error = dmi_walk(decode: dmi_sysfs_register_handle, private_data: &val);
674 if (error)
675 goto err;
676 if (val) {
677 error = val;
678 goto err;
679 }
680
681 pr_debug("dmi-sysfs: loaded.\n");
682
683 return 0;
684err:
685 cleanup_entry_list();
686 kset_unregister(kset: dmi_kset);
687 return error;
688}
689
690/* clean up everything. */
691static void __exit dmi_sysfs_exit(void)
692{
693 pr_debug("dmi-sysfs: unloading.\n");
694 cleanup_entry_list();
695 kset_unregister(kset: dmi_kset);
696}
697
698module_init(dmi_sysfs_init);
699module_exit(dmi_sysfs_exit);
700
701MODULE_AUTHOR("Mike Waychison <mikew@google.com>");
702MODULE_DESCRIPTION("DMI sysfs support");
703MODULE_LICENSE("GPL");
704

source code of linux/drivers/firmware/dmi-sysfs.c