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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * vpd.c
4 *
5 * Driver for exporting VPD content to sysfs.
6 *
7 * Copyright 2017 Google Inc.
8 */
9
10#include <linux/ctype.h>
11#include <linux/init.h>
12#include <linux/io.h>
13#include <linux/kernel.h>
14#include <linux/kobject.h>
15#include <linux/list.h>
16#include <linux/device-id/coreboot.h>
17#include <linux/module.h>
18#include <linux/of_address.h>
19#include <linux/platform_device.h>
20#include <linux/slab.h>
21#include <linux/sysfs.h>
22
23#include "coreboot_table.h"
24#include "vpd_decode.h"
25
26#define CB_TAG_VPD 0x2c
27#define VPD_CBMEM_MAGIC 0x43524f53
28
29static struct kobject *vpd_kobj;
30
31struct vpd_cbmem {
32 u32 magic;
33 u32 version;
34 u32 ro_size;
35 u32 rw_size;
36 u8 blob[];
37};
38
39struct vpd_section {
40 bool enabled;
41 const char *name;
42 char *raw_name; /* the string name_raw */
43 struct kobject *kobj; /* vpd/name directory */
44 char *baseaddr;
45 struct bin_attribute bin_attr; /* vpd/name_raw bin_attribute */
46 struct list_head attribs; /* key/value in vpd_attrib_info list */
47};
48
49struct vpd_attrib_info {
50 char *key;
51 const char *value;
52 struct bin_attribute bin_attr;
53 struct list_head list;
54};
55
56static struct vpd_section ro_vpd;
57static struct vpd_section rw_vpd;
58
59static ssize_t vpd_attrib_read(struct file *filp, struct kobject *kobp,
60 const struct bin_attribute *bin_attr, char *buf,
61 loff_t pos, size_t count)
62{
63 struct vpd_attrib_info *info = bin_attr->private;
64
65 return memory_read_from_buffer(buf, count, &pos, info->value,
66 info->bin_attr.size);
67}
68
69/*
70 * vpd_section_check_key_name()
71 *
72 * The VPD specification supports only [a-zA-Z0-9_]+ characters in key names but
73 * old firmware versions may have entries like "S/N" which are problematic when
74 * exporting them as sysfs attributes. These keys present in old firmwares are
75 * ignored.
76 *
77 * Returns VPD_OK for a valid key name, VPD_FAIL otherwise.
78 *
79 * @key: The key name to check
80 * @key_len: key name length
81 */
82static int vpd_section_check_key_name(const u8 *key, s32 key_len)
83{
84 int c;
85
86 while (key_len-- > 0) {
87 c = *key++;
88
89 if (!isalnum(c) && c != '_')
90 return VPD_FAIL;
91 }
92
93 return VPD_OK;
94}
95
96static int vpd_section_attrib_add(const u8 *key, u32 key_len,
97 const u8 *value, u32 value_len,
98 void *arg)
99{
100 int ret;
101 struct vpd_section *sec = arg;
102 struct vpd_attrib_info *info;
103
104 /*
105 * Return VPD_OK immediately to decode next entry if the current key
106 * name contains invalid characters.
107 */
108 if (vpd_section_check_key_name(key, key_len) != VPD_OK)
109 return VPD_OK;
110
111 info = kzalloc_obj(*info);
112 if (!info)
113 return -ENOMEM;
114
115 info->key = kstrndup(key, key_len, GFP_KERNEL);
116 if (!info->key) {
117 ret = -ENOMEM;
118 goto free_info;
119 }
120
121 sysfs_bin_attr_init(&info->bin_attr);
122 info->bin_attr.attr.name = info->key;
123 info->bin_attr.attr.mode = 0444;
124 info->bin_attr.size = value_len;
125 info->bin_attr.read = vpd_attrib_read;
126 info->bin_attr.private = info;
127
128 info->value = value;
129
130 INIT_LIST_HEAD(&info->list);
131
132 ret = sysfs_create_bin_file(sec->kobj, &info->bin_attr);
133 if (ret)
134 goto free_info_key;
135
136 list_add_tail(&info->list, &sec->attribs);
137 return 0;
138
139free_info_key:
140 kfree(info->key);
141free_info:
142 kfree(info);
143
144 return ret;
145}
146
147static void vpd_section_attrib_destroy(struct vpd_section *sec)
148{
149 struct vpd_attrib_info *info;
150 struct vpd_attrib_info *temp;
151
152 list_for_each_entry_safe(info, temp, &sec->attribs, list) {
153 sysfs_remove_bin_file(sec->kobj, &info->bin_attr);
154 kfree(info->key);
155 kfree(info);
156 }
157}
158
159static ssize_t vpd_section_read(struct file *filp, struct kobject *kobp,
160 const struct bin_attribute *bin_attr, char *buf,
161 loff_t pos, size_t count)
162{
163 struct vpd_section *sec = bin_attr->private;
164
165 return memory_read_from_buffer(buf, count, &pos, sec->baseaddr,
166 sec->bin_attr.size);
167}
168
169static int vpd_section_create_attribs(struct vpd_section *sec)
170{
171 s32 consumed;
172 int ret;
173
174 consumed = 0;
175 do {
176 ret = vpd_decode_string(sec->bin_attr.size, sec->baseaddr,
177 &consumed, vpd_section_attrib_add, sec);
178 } while (ret == VPD_OK);
179
180 return 0;
181}
182
183static int vpd_section_init(const char *name, struct vpd_section *sec,
184 phys_addr_t physaddr, size_t size)
185{
186 int err;
187
188 sec->baseaddr = memremap(physaddr, size, MEMREMAP_WB);
189 if (!sec->baseaddr)
190 return -ENOMEM;
191
192 sec->name = name;
193
194 /* We want to export the raw partition with name ${name}_raw */
195 sec->raw_name = kasprintf(GFP_KERNEL, "%s_raw", name);
196 if (!sec->raw_name) {
197 err = -ENOMEM;
198 goto err_memunmap;
199 }
200
201 sysfs_bin_attr_init(&sec->bin_attr);
202 sec->bin_attr.attr.name = sec->raw_name;
203 sec->bin_attr.attr.mode = 0444;
204 sec->bin_attr.size = size;
205 sec->bin_attr.read = vpd_section_read;
206 sec->bin_attr.private = sec;
207
208 err = sysfs_create_bin_file(vpd_kobj, &sec->bin_attr);
209 if (err)
210 goto err_free_raw_name;
211
212 sec->kobj = kobject_create_and_add(name, vpd_kobj);
213 if (!sec->kobj) {
214 err = -EINVAL;
215 goto err_sysfs_remove;
216 }
217
218 INIT_LIST_HEAD(&sec->attribs);
219 vpd_section_create_attribs(sec);
220
221 sec->enabled = true;
222
223 return 0;
224
225err_sysfs_remove:
226 sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr);
227err_free_raw_name:
228 kfree(sec->raw_name);
229err_memunmap:
230 memunmap(sec->baseaddr);
231 return err;
232}
233
234static int vpd_section_destroy(struct vpd_section *sec)
235{
236 if (sec->enabled) {
237 vpd_section_attrib_destroy(sec);
238 kobject_put(sec->kobj);
239 sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr);
240 kfree(sec->raw_name);
241 memunmap(sec->baseaddr);
242 sec->enabled = false;
243 }
244
245 return 0;
246}
247
248static int vpd_sections_init(phys_addr_t physaddr)
249{
250 struct vpd_cbmem *temp;
251 struct vpd_cbmem header;
252 int ret = 0;
253
254 temp = memremap(physaddr, sizeof(struct vpd_cbmem), MEMREMAP_WB);
255 if (!temp)
256 return -ENOMEM;
257
258 memcpy(&header, temp, sizeof(struct vpd_cbmem));
259 memunmap(temp);
260
261 if (header.magic != VPD_CBMEM_MAGIC)
262 return -ENODEV;
263
264 if (header.ro_size) {
265 ret = vpd_section_init("ro", &ro_vpd,
266 physaddr + sizeof(struct vpd_cbmem),
267 header.ro_size);
268 if (ret)
269 return ret;
270 }
271
272 if (header.rw_size) {
273 ret = vpd_section_init("rw", &rw_vpd,
274 physaddr + sizeof(struct vpd_cbmem) +
275 header.ro_size, header.rw_size);
276 if (ret) {
277 vpd_section_destroy(&ro_vpd);
278 return ret;
279 }
280 }
281
282 return 0;
283}
284
285static int vpd_probe(struct coreboot_device *dev)
286{
287 int ret;
288
289 vpd_kobj = kobject_create_and_add("vpd", firmware_kobj);
290 if (!vpd_kobj)
291 return -ENOMEM;
292
293 ret = vpd_sections_init(dev->cbmem_ref.cbmem_addr);
294 if (ret) {
295 kobject_put(vpd_kobj);
296 return ret;
297 }
298
299 return 0;
300}
301
302static void vpd_remove(struct coreboot_device *dev)
303{
304 vpd_section_destroy(&ro_vpd);
305 vpd_section_destroy(&rw_vpd);
306
307 kobject_put(vpd_kobj);
308}
309
310static const struct coreboot_device_id vpd_ids[] = {
311 { .tag = CB_TAG_VPD },
312 { /* sentinel */ }
313};
314MODULE_DEVICE_TABLE(coreboot, vpd_ids);
315
316static struct coreboot_driver vpd_driver = {
317 .probe = vpd_probe,
318 .remove = vpd_remove,
319 .drv = {
320 .name = "vpd",
321 },
322 .id_table = vpd_ids,
323};
324module_coreboot_driver(vpd_driver);
325
326MODULE_AUTHOR("Google, Inc.");
327MODULE_DESCRIPTION("Driver for exporting Vital Product Data content to sysfs");
328MODULE_LICENSE("GPL");