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
 139         ret = sysfs_create_bin_file(sec->kobj, &info->bin_attr);
 140         if (ret)
 141                 goto free_info_key;
 142
 143         list_add_tail(&info->list, &sec->attribs);
 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                 sysfs_remove_bin_file(sec->kobj, &info->bin_attr);
 161                 kfree(info->key);
 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 err;
 194
 195         sec->baseaddr = memremap(physaddr, size, MEMREMAP_WB);
 196         if (!sec->baseaddr)
 197                 return -ENOMEM;
 198
 199         sec->name = name;
 200
 201         /* We want to export the raw partion with name ${name}_raw */
 202         sec->raw_name = kasprintf(GFP_KERNEL, "%s_raw", name);
 203         if (!sec->raw_name) {
 204                 err = -ENOMEM;
 205                 goto err_memunmap;
 206         }
 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         err = sysfs_create_bin_file(vpd_kobj, &sec->bin_attr);
 216         if (err)
 217                 goto err_free_raw_name;
 218
 219         sec->kobj = kobject_create_and_add(name, vpd_kobj);
 220         if (!sec->kobj) {
 221                 err = -EINVAL;
 222                 goto err_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 err_sysfs_remove:
 233         sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr);
 234 err_free_raw_name:
 235         kfree(sec->raw_name);
 236 err_memunmap:
 237         memunmap(sec->baseaddr);
 238         return err;
 239 }
 240
 241 static int vpd_section_destroy(struct vpd_section *sec)
 242 {
 243         if (sec->enabled) {
 244                 vpd_section_attrib_destroy(sec);
 245                 kobject_put(sec->kobj);
 246                 sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr);
 247                 kfree(sec->raw_name);
 248                 memunmap(sec->baseaddr);
 249         }
 250
 251         return 0;
 252 }
 253
 254 static int vpd_sections_init(phys_addr_t physaddr)
 255 {
 256         struct vpd_cbmem __iomem *temp;
 257         struct vpd_cbmem header;
 258         int ret = 0;
 259
 260         temp = memremap(physaddr, sizeof(struct vpd_cbmem), MEMREMAP_WB);
 261         if (!temp)
 262                 return -ENOMEM;
 263
 264         memcpy_fromio(&header, temp, sizeof(struct vpd_cbmem));
 265         memunmap(temp);
 266
 267         if (header.magic != VPD_CBMEM_MAGIC)
 268                 return -ENODEV;
 269
 270         if (header.ro_size) {
 271                 ret = vpd_section_init("ro", &ro_vpd,
 272                                        physaddr + sizeof(struct vpd_cbmem),
 273                                        header.ro_size);
 274                 if (ret)
 275                         return ret;
 276         }
 277
 278         if (header.rw_size) {
 279                 ret = vpd_section_init("rw", &rw_vpd,
 280                                        physaddr + sizeof(struct vpd_cbmem) +
 281                                        header.ro_size, header.rw_size);
 282                 if (ret)
 283                         return ret;
 284         }
 285
 286         return 0;
 287 }
 288
 289 static int vpd_probe(struct platform_device *pdev)
 290 {
 291         int ret;
 292         struct lb_cbmem_ref entry;
 293
 294         ret = coreboot_table_find(CB_TAG_VPD, &entry, sizeof(entry));
 295         if (ret)
 296                 return ret;
 297
 298         vpd_kobj = kobject_create_and_add("vpd", firmware_kobj);
 299         if (!vpd_kobj)
 300                 return -ENOMEM;
 301
 302         ret = vpd_sections_init(entry.cbmem_addr);
 303         if (ret) {
 304                 kobject_put(vpd_kobj);
 305                 return ret;
 306         }
 307
 308         return 0;
 309 }
 310
 311 static int vpd_remove(struct platform_device *pdev)
 312 {
 313         vpd_section_destroy(&ro_vpd);
 314         vpd_section_destroy(&rw_vpd);
 315
 316         kobject_put(vpd_kobj);
 317
 318         return 0;
 319 }
 320
 321 static struct platform_driver vpd_driver = {
 322         .probe = vpd_probe,
 323         .remove = vpd_remove,
 324         .driver = {
 325                 .name = "vpd",
 326         },
 327 };
 328
 329 static struct platform_device *vpd_pdev;
 330
 331 static int __init vpd_platform_init(void)
 332 {
 333         int ret;
 334
 335         ret = platform_driver_register(&vpd_driver);
 336         if (ret)
 337                 return ret;
 338
 339         vpd_pdev = platform_device_register_simple("vpd", -1, NULL, 0);
 340         if (IS_ERR(vpd_pdev)) {
 341                 platform_driver_unregister(&vpd_driver);
 342                 return PTR_ERR(vpd_pdev);
 343         }
 344
 345         return 0;
 346 }
 347
 348 static void __exit vpd_platform_exit(void)
 349 {
 350         platform_device_unregister(vpd_pdev);
 351         platform_driver_unregister(&vpd_driver);
 352 }
 353
 354 module_init(vpd_platform_init);
 355 module_exit(vpd_platform_exit);
 356
 357 MODULE_AUTHOR("Google, Inc.");
 358 MODULE_LICENSE("GPL");