drivers/firmware/google/vpd.c

   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");