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