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         if (!info)
 120                 return -ENOMEM;
 121
 122         info->key = kstrndup(key, key_len, GFP_KERNEL);
 123         if (!info->key) {
 124                 ret = -ENOMEM;
 125                 goto free_info;
 126         }
 127
 128         sysfs_bin_attr_init(&info->bin_attr);
 129         info->bin_attr.attr.name = info->key;
 130         info->bin_attr.attr.mode = 0444;
 131         info->bin_attr.size = value_len;
 132         info->bin_attr.read = vpd_attrib_read;
 133         info->bin_attr.private = info;
 134
 135         info->value = value;
 136
 137         INIT_LIST_HEAD(&info->list);
 138         list_add_tail(&info->list, &sec->attribs);
 139
 140         ret = sysfs_create_bin_file(sec->kobj, &info->bin_attr);
 141         if (ret)
 142                 goto free_info_key;
 143
 144         return 0;
 145
 146 free_info_key:
 147         kfree(info->key);
 148 free_info:
 149         kfree(info);
 150
 151         return ret;
 152 }
 153
 154 static void vpd_section_attrib_destroy(struct vpd_section *sec)
 155 {
 156         struct vpd_attrib_info *info;
 157         struct vpd_attrib_info *temp;
 158
 159         list_for_each_entry_safe(info, temp, &sec->attribs, list) {
 160                 kfree(info->key);
 161                 sysfs_remove_bin_file(sec->kobj, &info->bin_attr);
 162                 kfree(info);
 163         }
 164 }
 165
 166 static ssize_t vpd_section_read(struct file *filp, struct kobject *kobp,
 167                                 struct bin_attribute *bin_attr, char *buf,
 168                                 loff_t pos, size_t count)
 169 {
 170         struct vpd_section *sec = bin_attr->private;
 171
 172         return memory_read_from_buffer(buf, count, &pos, sec->baseaddr,
 173                                        sec->bin_attr.size);
 174 }
 175
 176 static int vpd_section_create_attribs(struct vpd_section *sec)
 177 {
 178         s32 consumed;
 179         int ret;
 180
 181         consumed = 0;
 182         do {
 183                 ret = vpd_decode_string(sec->bin_attr.size, sec->baseaddr,
 184                                         &consumed, vpd_section_attrib_add, sec);
 185         } while (ret == VPD_OK);
 186
 187         return 0;
 188 }
 189
 190 static int vpd_section_init(const char *name, struct vpd_section *sec,
 191                             phys_addr_t physaddr, size_t size)
 192 {
 193         int ret;
 194         int raw_len;
 195
 196         sec->baseaddr = memremap(physaddr, size, MEMREMAP_WB);
 197         if (!sec->baseaddr)
 198                 return -ENOMEM;
 199
 200         sec->name = name;
 201
 202         /* We want to export the raw partion with name ${name}_raw */
 203         raw_len = strlen(name) + 5;
 204         sec->raw_name = kzalloc(raw_len, GFP_KERNEL);
 205         strncpy(sec->raw_name, name, raw_len);
 206         strncat(sec->raw_name, "_raw", raw_len);
 207
 208         sysfs_bin_attr_init(&sec->bin_attr);
 209         sec->bin_attr.attr.name = sec->raw_name;
 210         sec->bin_attr.attr.mode = 0444;
 211         sec->bin_attr.size = size;
 212         sec->bin_attr.read = vpd_section_read;
 213         sec->bin_attr.private = sec;
 214
 215         ret = sysfs_create_bin_file(vpd_kobj, &sec->bin_attr);
 216         if (ret)
 217                 goto free_sec;
 218
 219         sec->kobj = kobject_create_and_add(name, vpd_kobj);
 220         if (!sec->kobj) {
 221                 ret = -EINVAL;
 222                 goto sysfs_remove;
 223         }
 224
 225         INIT_LIST_HEAD(&sec->attribs);
 226         vpd_section_create_attribs(sec);
 227
 228         sec->enabled = true;
 229
 230         return 0;
 231
 232 sysfs_remove:
 233         sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr);
 234
 235 free_sec:
 236         kfree(sec->raw_name);
 237         iounmap(sec->baseaddr);
 238
 239         return ret;
 240 }
 241
 242 static int vpd_section_destroy(struct vpd_section *sec)
 243 {
 244         if (sec->enabled) {
 245                 vpd_section_attrib_destroy(sec);
 246                 kobject_del(sec->kobj);
 247                 sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr);
 248                 kfree(sec->raw_name);
 249                 iounmap(sec->baseaddr);
 250         }
 251
 252         return 0;
 253 }
 254
 255 static int vpd_sections_init(phys_addr_t physaddr)
 256 {
 257         struct vpd_cbmem __iomem *temp;
 258         struct vpd_cbmem header;
 259         int ret = 0;
 260
 261         temp = memremap(physaddr, sizeof(struct vpd_cbmem), MEMREMAP_WB);
 262         if (!temp)
 263                 return -ENOMEM;
 264
 265         memcpy_fromio(&header, temp, sizeof(struct vpd_cbmem));
 266         iounmap(temp);
 267
 268         if (header.magic != VPD_CBMEM_MAGIC)
 269                 return -ENODEV;
 270
 271         if (header.ro_size) {
 272                 ret = vpd_section_init("ro", &ro_vpd,
 273                                        physaddr + sizeof(struct vpd_cbmem),
 274                                        header.ro_size);
 275                 if (ret)
 276                         return ret;
 277         }
 278
 279         if (header.rw_size) {
 280                 ret = vpd_section_init("rw", &rw_vpd,
 281                                        physaddr + sizeof(struct vpd_cbmem) +
 282                                        header.ro_size, header.rw_size);
 283                 if (ret)
 284                         return ret;
 285         }
 286
 287         return 0;
 288 }
 289
 290 static int vpd_probe(struct platform_device *pdev)
 291 {
 292         int ret;
 293         struct lb_cbmem_ref entry;
 294
 295         ret = coreboot_table_find(CB_TAG_VPD, &entry, sizeof(entry));
 296         if (ret)
 297                 return ret;
 298
 299         return vpd_sections_init(entry.cbmem_addr);
 300 }
 301
 302 static struct platform_driver vpd_driver = {
 303         .probe = vpd_probe,
 304         .driver = {
 305                 .name = "vpd",
 306         },
 307 };
 308
 309 static int __init vpd_platform_init(void)
 310 {
 311         struct platform_device *pdev;
 312
 313         pdev = platform_device_register_simple("vpd", -1, NULL, 0);
 314         if (IS_ERR(pdev))
 315                 return PTR_ERR(pdev);
 316
 317         vpd_kobj = kobject_create_and_add("vpd", firmware_kobj);
 318         if (!vpd_kobj)
 319                 return -ENOMEM;
 320
 321         memset(&ro_vpd, 0, sizeof(ro_vpd));
 322         memset(&rw_vpd, 0, sizeof(rw_vpd));
 323
 324         platform_driver_register(&vpd_driver);
 325
 326         return 0;
 327 }
 328
 329 static void __exit vpd_platform_exit(void)
 330 {
 331         vpd_section_destroy(&ro_vpd);
 332         vpd_section_destroy(&rw_vpd);
 333         kobject_del(vpd_kobj);
 334 }
 335
 336 module_init(vpd_platform_init);
 337 module_exit(vpd_platform_exit);
 338
 339 MODULE_AUTHOR("Google, Inc.");
 340 MODULE_LICENSE("GPL");