drivers/firmware/google/vpd.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * vpd.c
   4  *
   5  * Driver for exporting VPD content to sysfs.
   6  *
   7  * Copyright 2017 Google Inc.
   8  */
   9
  10 #include <linux/ctype.h>
  11 #include <linux/init.h>
  12 #include <linux/io.h>
  13 #include <linux/kernel.h>
  14 #include <linux/kobject.h>
  15 #include <linux/list.h>
  16 #include <linux/module.h>
  17 #include <linux/of_address.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/slab.h>
  20 #include <linux/sysfs.h>
  21
  22 #include "coreboot_table.h"
  23 #include "vpd_decode.h"
  24
  25 #define CB_TAG_VPD      0x2c
  26 #define VPD_CBMEM_MAGIC 0x43524f53
  27
  28 static struct kobject *vpd_kobj;
  29
  30 struct vpd_cbmem {
  31         u32 magic;
  32         u32 version;
  33         u32 ro_size;
  34         u32 rw_size;
  35         u8  blob[];
  36 };
  37
  38 struct vpd_section {
  39         bool enabled;
  40         const char *name;
  41         char *raw_name;                /* the string name_raw */
  42         struct kobject *kobj;          /* vpd/name directory */
  43         char *baseaddr;
  44         struct bin_attribute bin_attr; /* vpd/name_raw bin_attribute */
  45         struct list_head attribs;      /* key/value in vpd_attrib_info list */
  46 };
  47
  48 struct vpd_attrib_info {
  49         char *key;
  50         const char *value;
  51         struct bin_attribute bin_attr;
  52         struct list_head list;
  53 };
  54
  55 static struct vpd_section ro_vpd;
  56 static struct vpd_section rw_vpd;
  57
  58 static ssize_t vpd_attrib_read(struct file *filp, struct kobject *kobp,
  59                                struct bin_attribute *bin_attr, char *buf,
  60                                loff_t pos, size_t count)
  61 {
  62         struct vpd_attrib_info *info = bin_attr->private;
  63
  64         return memory_read_from_buffer(buf, count, &pos, info->value,
  65                                        info->bin_attr.size);
  66 }
  67
  68 /*
  69  * vpd_section_check_key_name()
  70  *
  71  * The VPD specification supports only [a-zA-Z0-9_]+ characters in key names but
  72  * old firmware versions may have entries like "S/N" which are problematic when
  73  * exporting them as sysfs attributes. These keys present in old firmwares are
  74  * ignored.
  75  *
  76  * Returns VPD_OK for a valid key name, VPD_FAIL otherwise.
  77  *
  78  * @key: The key name to check
  79  * @key_len: key name length
  80  */
  81 static int vpd_section_check_key_name(const u8 *key, s32 key_len)
  82 {
  83         int c;
  84
  85         while (key_len-- > 0) {
  86                 c = *key++;
  87
  88                 if (!isalnum(c) && c != '_')
  89                         return VPD_FAIL;
  90         }
  91
  92         return VPD_OK;
  93 }
  94
  95 static int vpd_section_attrib_add(const u8 *key, u32 key_len,
  96                                   const u8 *value, u32 value_len,
  97                                   void *arg)
  98 {
  99         int ret;
 100         struct vpd_section *sec = arg;
 101         struct vpd_attrib_info *info;
 102
 103         /*
 104          * Return VPD_OK immediately to decode next entry if the current key
 105          * name contains invalid characters.
 106          */
 107         if (vpd_section_check_key_name(key, key_len) != VPD_OK)
 108                 return VPD_OK;
 109
 110         info = kzalloc(sizeof(*info), GFP_KERNEL);
 111         if (!info)
 112                 return -ENOMEM;
 113
 114         info->key = kstrndup(key, key_len, GFP_KERNEL);
 115         if (!info->key) {
 116                 ret = -ENOMEM;
 117                 goto free_info;
 118         }
 119
 120         sysfs_bin_attr_init(&info->bin_attr);
 121         info->bin_attr.attr.name = info->key;
 122         info->bin_attr.attr.mode = 0444;
 123         info->bin_attr.size = value_len;
 124         info->bin_attr.read = vpd_attrib_read;
 125         info->bin_attr.private = info;
 126
 127         info->value = value;
 128
 129         INIT_LIST_HEAD(&info->list);
 130
 131         ret = sysfs_create_bin_file(sec->kobj, &info->bin_attr);
 132         if (ret)
 133                 goto free_info_key;
 134
 135         list_add_tail(&info->list, &sec->attribs);
 136         return 0;
 137
 138 free_info_key:
 139         kfree(info->key);
 140 free_info:
 141         kfree(info);
 142
 143         return ret;
 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                 sysfs_remove_bin_file(sec->kobj, &info->bin_attr);
 153                 kfree(info->key);
 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 err;
 186
 187         sec->baseaddr = memremap(physaddr, size, MEMREMAP_WB);
 188         if (!sec->baseaddr)
 189                 return -ENOMEM;
 190
 191         sec->name = name;
 192
 193         /* We want to export the raw partition with name ${name}_raw */
 194         sec->raw_name = kasprintf(GFP_KERNEL, "%s_raw", name);
 195         if (!sec->raw_name) {
 196                 err = -ENOMEM;
 197                 goto err_memunmap;
 198         }
 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         err = sysfs_create_bin_file(vpd_kobj, &sec->bin_attr);
 208         if (err)
 209                 goto err_free_raw_name;
 210
 211         sec->kobj = kobject_create_and_add(name, vpd_kobj);
 212         if (!sec->kobj) {
 213                 err = -EINVAL;
 214                 goto err_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 err_sysfs_remove:
 225         sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr);
 226 err_free_raw_name:
 227         kfree(sec->raw_name);
 228 err_memunmap:
 229         memunmap(sec->baseaddr);
 230         return err;
 231 }
 232
 233 static int vpd_section_destroy(struct vpd_section *sec)
 234 {
 235         if (sec->enabled) {
 236                 vpd_section_attrib_destroy(sec);
 237                 kobject_put(sec->kobj);
 238                 sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr);
 239                 kfree(sec->raw_name);
 240                 memunmap(sec->baseaddr);
 241                 sec->enabled = false;
 242         }
 243
 244         return 0;
 245 }
 246
 247 static int vpd_sections_init(phys_addr_t physaddr)
 248 {
 249         struct vpd_cbmem *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(&header, temp, sizeof(struct vpd_cbmem));
 258         memunmap(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                         vpd_section_destroy(&ro_vpd);
 277                         return ret;
 278                 }
 279         }
 280
 281         return 0;
 282 }
 283
 284 static int vpd_probe(struct coreboot_device *dev)
 285 {
 286         int ret;
 287
 288         vpd_kobj = kobject_create_and_add("vpd", firmware_kobj);
 289         if (!vpd_kobj)
 290                 return -ENOMEM;
 291
 292         ret = vpd_sections_init(dev->cbmem_ref.cbmem_addr);
 293         if (ret) {
 294                 kobject_put(vpd_kobj);
 295                 return ret;
 296         }
 297
 298         return 0;
 299 }
 300
 301 static int vpd_remove(struct coreboot_device *dev)
 302 {
 303         vpd_section_destroy(&ro_vpd);
 304         vpd_section_destroy(&rw_vpd);
 305
 306         kobject_put(vpd_kobj);
 307
 308         return 0;
 309 }
 310
 311 static struct coreboot_driver vpd_driver = {
 312         .probe = vpd_probe,
 313         .remove = vpd_remove,
 314         .drv = {
 315                 .name = "vpd",
 316         },
 317         .tag = CB_TAG_VPD,
 318 };
 319 module_coreboot_driver(vpd_driver);
 320
 321 MODULE_AUTHOR("Google, Inc.");
 322 MODULE_LICENSE("GPL");