1 /* 2 * vpd.c 3 * 4 * Driver for exporting VPD content to sysfs. 5 * 6 * Copyright 2017 Google Inc. 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License v2.0 as published by 10 * the Free Software Foundation. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 */ 17 18 #include <linux/ctype.h> 19 #include <linux/init.h> 20 #include <linux/io.h> 21 #include <linux/kernel.h> 22 #include <linux/kobject.h> 23 #include <linux/list.h> 24 #include <linux/module.h> 25 #include <linux/of_address.h> 26 #include <linux/platform_device.h> 27 #include <linux/slab.h> 28 #include <linux/sysfs.h> 29 30 #include "coreboot_table.h" 31 #include "vpd_decode.h" 32 33 #define CB_TAG_VPD 0x2c 34 #define VPD_CBMEM_MAGIC 0x43524f53 35 36 static struct kobject *vpd_kobj; 37 38 struct vpd_cbmem { 39 u32 magic; 40 u32 version; 41 u32 ro_size; 42 u32 rw_size; 43 u8 blob[0]; 44 }; 45 46 struct vpd_section { 47 bool enabled; 48 const char *name; 49 char *raw_name; /* the string name_raw */ 50 struct kobject *kobj; /* vpd/name directory */ 51 char *baseaddr; 52 struct bin_attribute bin_attr; /* vpd/name_raw bin_attribute */ 53 struct list_head attribs; /* key/value in vpd_attrib_info list */ 54 }; 55 56 struct vpd_attrib_info { 57 char *key; 58 const char *value; 59 struct bin_attribute bin_attr; 60 struct list_head list; 61 }; 62 63 static struct vpd_section ro_vpd; 64 static struct vpd_section rw_vpd; 65 66 static ssize_t vpd_attrib_read(struct file *filp, struct kobject *kobp, 67 struct bin_attribute *bin_attr, char *buf, 68 loff_t pos, size_t count) 69 { 70 struct vpd_attrib_info *info = bin_attr->private; 71 72 return memory_read_from_buffer(buf, count, &pos, info->value, 73 info->bin_attr.size); 74 } 75 76 /* 77 * vpd_section_check_key_name() 78 * 79 * The VPD specification supports only [a-zA-Z0-9_]+ characters in key names but 80 * old firmware versions may have entries like "S/N" which are problematic when 81 * exporting them as sysfs attributes. These keys present in old firmwares are 82 * ignored. 83 * 84 * Returns VPD_OK for a valid key name, VPD_FAIL otherwise. 85 * 86 * @key: The key name to check 87 * @key_len: key name length 88 */ 89 static int vpd_section_check_key_name(const u8 *key, s32 key_len) 90 { 91 int c; 92 93 while (key_len-- > 0) { 94 c = *key++; 95 96 if (!isalnum(c) && c != '_') 97 return VPD_FAIL; 98 } 99 100 return VPD_OK; 101 } 102 103 static int vpd_section_attrib_add(const u8 *key, s32 key_len, 104 const u8 *value, s32 value_len, 105 void *arg) 106 { 107 int ret; 108 struct vpd_section *sec = arg; 109 struct vpd_attrib_info *info; 110 111 /* 112 * Return VPD_OK immediately to decode next entry if the current key 113 * name contains invalid characters. 114 */ 115 if (vpd_section_check_key_name(key, key_len) != VPD_OK) 116 return VPD_OK; 117 118 info = kzalloc(sizeof(*info), GFP_KERNEL); 119 info->key = kzalloc(key_len + 1, GFP_KERNEL); 120 if (!info->key) 121 return -ENOMEM; 122 123 memcpy(info->key, key, key_len); 124 125 sysfs_bin_attr_init(&info->bin_attr); 126 info->bin_attr.attr.name = info->key; 127 info->bin_attr.attr.mode = 0444; 128 info->bin_attr.size = value_len; 129 info->bin_attr.read = vpd_attrib_read; 130 info->bin_attr.private = info; 131 132 info->value = value; 133 134 INIT_LIST_HEAD(&info->list); 135 list_add_tail(&info->list, &sec->attribs); 136 137 ret = sysfs_create_bin_file(sec->kobj, &info->bin_attr); 138 if (ret) { 139 kfree(info->key); 140 return ret; 141 } 142 143 return 0; 144 } 145 146 static void vpd_section_attrib_destroy(struct vpd_section *sec) 147 { 148 struct vpd_attrib_info *info; 149 struct vpd_attrib_info *temp; 150 151 list_for_each_entry_safe(info, temp, &sec->attribs, list) { 152 kfree(info->key); 153 sysfs_remove_bin_file(sec->kobj, &info->bin_attr); 154 kfree(info); 155 } 156 } 157 158 static ssize_t vpd_section_read(struct file *filp, struct kobject *kobp, 159 struct bin_attribute *bin_attr, char *buf, 160 loff_t pos, size_t count) 161 { 162 struct vpd_section *sec = bin_attr->private; 163 164 return memory_read_from_buffer(buf, count, &pos, sec->baseaddr, 165 sec->bin_attr.size); 166 } 167 168 static int vpd_section_create_attribs(struct vpd_section *sec) 169 { 170 s32 consumed; 171 int ret; 172 173 consumed = 0; 174 do { 175 ret = vpd_decode_string(sec->bin_attr.size, sec->baseaddr, 176 &consumed, vpd_section_attrib_add, sec); 177 } while (ret == VPD_OK); 178 179 return 0; 180 } 181 182 static int vpd_section_init(const char *name, struct vpd_section *sec, 183 phys_addr_t physaddr, size_t size) 184 { 185 int ret; 186 int raw_len; 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 partion with name ${name}_raw */ 195 raw_len = strlen(name) + 5; 196 sec->raw_name = kzalloc(raw_len, GFP_KERNEL); 197 strncpy(sec->raw_name, name, raw_len); 198 strncat(sec->raw_name, "_raw", raw_len); 199 200 sysfs_bin_attr_init(&sec->bin_attr); 201 sec->bin_attr.attr.name = sec->raw_name; 202 sec->bin_attr.attr.mode = 0444; 203 sec->bin_attr.size = size; 204 sec->bin_attr.read = vpd_section_read; 205 sec->bin_attr.private = sec; 206 207 ret = sysfs_create_bin_file(vpd_kobj, &sec->bin_attr); 208 if (ret) 209 goto free_sec; 210 211 sec->kobj = kobject_create_and_add(name, vpd_kobj); 212 if (!sec->kobj) { 213 ret = -EINVAL; 214 goto sysfs_remove; 215 } 216 217 INIT_LIST_HEAD(&sec->attribs); 218 vpd_section_create_attribs(sec); 219 220 sec->enabled = true; 221 222 return 0; 223 224 sysfs_remove: 225 sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr); 226 227 free_sec: 228 kfree(sec->raw_name); 229 iounmap(sec->baseaddr); 230 231 return ret; 232 } 233 234 static int vpd_section_destroy(struct vpd_section *sec) 235 { 236 if (sec->enabled) { 237 vpd_section_attrib_destroy(sec); 238 kobject_del(sec->kobj); 239 sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr); 240 kfree(sec->raw_name); 241 iounmap(sec->baseaddr); 242 } 243 244 return 0; 245 } 246 247 static int vpd_sections_init(phys_addr_t physaddr) 248 { 249 struct vpd_cbmem __iomem *temp; 250 struct vpd_cbmem header; 251 int ret = 0; 252 253 temp = memremap(physaddr, sizeof(struct vpd_cbmem), MEMREMAP_WB); 254 if (!temp) 255 return -ENOMEM; 256 257 memcpy_fromio(&header, temp, sizeof(struct vpd_cbmem)); 258 iounmap(temp); 259 260 if (header.magic != VPD_CBMEM_MAGIC) 261 return -ENODEV; 262 263 if (header.ro_size) { 264 ret = vpd_section_init("ro", &ro_vpd, 265 physaddr + sizeof(struct vpd_cbmem), 266 header.ro_size); 267 if (ret) 268 return ret; 269 } 270 271 if (header.rw_size) { 272 ret = vpd_section_init("rw", &rw_vpd, 273 physaddr + sizeof(struct vpd_cbmem) + 274 header.ro_size, header.rw_size); 275 if (ret) 276 return ret; 277 } 278 279 return 0; 280 } 281 282 static int vpd_probe(struct platform_device *pdev) 283 { 284 int ret; 285 struct lb_cbmem_ref entry; 286 287 ret = coreboot_table_find(CB_TAG_VPD, &entry, sizeof(entry)); 288 if (ret) 289 return ret; 290 291 return vpd_sections_init(entry.cbmem_addr); 292 } 293 294 static struct platform_driver vpd_driver = { 295 .probe = vpd_probe, 296 .driver = { 297 .name = "vpd", 298 }, 299 }; 300 301 static int __init vpd_platform_init(void) 302 { 303 struct platform_device *pdev; 304 305 pdev = platform_device_register_simple("vpd", -1, NULL, 0); 306 if (IS_ERR(pdev)) 307 return PTR_ERR(pdev); 308 309 vpd_kobj = kobject_create_and_add("vpd", firmware_kobj); 310 if (!vpd_kobj) 311 return -ENOMEM; 312 313 memset(&ro_vpd, 0, sizeof(ro_vpd)); 314 memset(&rw_vpd, 0, sizeof(rw_vpd)); 315 316 platform_driver_register(&vpd_driver); 317 318 return 0; 319 } 320 321 static void __exit vpd_platform_exit(void) 322 { 323 vpd_section_destroy(&ro_vpd); 324 vpd_section_destroy(&rw_vpd); 325 kobject_del(vpd_kobj); 326 } 327 328 module_init(vpd_platform_init); 329 module_exit(vpd_platform_exit); 330 331 MODULE_AUTHOR("Google, Inc."); 332 MODULE_LICENSE("GPL"); 333