firmware/google/vpd.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * vpd.c
0004  *
0005  * Driver for exporting VPD content to sysfs.
0006  *
0007  * Copyright 2017 Google Inc.
0008  */
0009
0010 #include <linux/ctype.h>
0011 #include <linux/init.h>
0012 #include <linux/io.h>
0013 #include <linux/kernel.h>
0014 #include <linux/kobject.h>
0015 #include <linux/list.h>
0016 #include <linux/module.h>
0017 #include <linux/of_address.h>
0018 #include <linux/platform_device.h>
0019 #include <linux/slab.h>
0020 #include <linux/sysfs.h>
0021
0022 #include "coreboot_table.h"
0023 #include "vpd_decode.h"
0024
0025 #define CB_TAG_VPD      0x2c
0026 #define VPD_CBMEM_MAGIC 0x43524f53
0027
0028 static struct kobject *vpd_kobj;
0029
0030 struct vpd_cbmem {
0031     u32 magic;
0032     u32 version;
0033     u32 ro_size;
0034     u32 rw_size;
0035     u8  blob[];
0036 };
0037
0038 struct vpd_section {
0039     bool enabled;
0040     const char *name;
0041     char *raw_name;                /* the string name_raw */
0042     struct kobject *kobj;          /* vpd/name directory */
0043     char *baseaddr;
0044     struct bin_attribute bin_attr; /* vpd/name_raw bin_attribute */
0045     struct list_head attribs;      /* key/value in vpd_attrib_info list */
0046 };
0047
0048 struct vpd_attrib_info {
0049     char *key;
0050     const char *value;
0051     struct bin_attribute bin_attr;
0052     struct list_head list;
0053 };
0054
0055 static struct vpd_section ro_vpd;
0056 static struct vpd_section rw_vpd;
0057
0058 static ssize_t vpd_attrib_read(struct file *filp, struct kobject *kobp,
0059                    struct bin_attribute *bin_attr, char *buf,
0060                    loff_t pos, size_t count)
0061 {
0062     struct vpd_attrib_info *info = bin_attr->private;
0063
0064     return memory_read_from_buffer(buf, count, &pos, info->value,
0065                        info->bin_attr.size);
0066 }
0067
0068 /*
0069  * vpd_section_check_key_name()
0070  *
0071  * The VPD specification supports only [a-zA-Z0-9_]+ characters in key names but
0072  * old firmware versions may have entries like "S/N" which are problematic when
0073  * exporting them as sysfs attributes. These keys present in old firmwares are
0074  * ignored.
0075  *
0076  * Returns VPD_OK for a valid key name, VPD_FAIL otherwise.
0077  *
0078  * @key: The key name to check
0079  * @key_len: key name length
0080  */
0081 static int vpd_section_check_key_name(const u8 *key, s32 key_len)
0082 {
0083     int c;
0084
0085     while (key_len-- > 0) {
0086         c = *key++;
0087
0088         if (!isalnum(c) && c != '_')
0089             return VPD_FAIL;
0090     }
0091
0092     return VPD_OK;
0093 }
0094
0095 static int vpd_section_attrib_add(const u8 *key, u32 key_len,
0096                   const u8 *value, u32 value_len,
0097                   void *arg)
0098 {
0099     int ret;
0100     struct vpd_section *sec = arg;
0101     struct vpd_attrib_info *info;
0102
0103     /*
0104      * Return VPD_OK immediately to decode next entry if the current key
0105      * name contains invalid characters.
0106      */
0107     if (vpd_section_check_key_name(key, key_len) != VPD_OK)
0108         return VPD_OK;
0109
0110     info = kzalloc(sizeof(*info), GFP_KERNEL);
0111     if (!info)
0112         return -ENOMEM;
0113
0114     info->key = kstrndup(key, key_len, GFP_KERNEL);
0115     if (!info->key) {
0116         ret = -ENOMEM;
0117         goto free_info;
0118     }
0119
0120     sysfs_bin_attr_init(&info->bin_attr);
0121     info->bin_attr.attr.name = info->key;
0122     info->bin_attr.attr.mode = 0444;
0123     info->bin_attr.size = value_len;
0124     info->bin_attr.read = vpd_attrib_read;
0125     info->bin_attr.private = info;
0126
0127     info->value = value;
0128
0129     INIT_LIST_HEAD(&info->list);
0130
0131     ret = sysfs_create_bin_file(sec->kobj, &info->bin_attr);
0132     if (ret)
0133         goto free_info_key;
0134
0135     list_add_tail(&info->list, &sec->attribs);
0136     return 0;
0137
0138 free_info_key:
0139     kfree(info->key);
0140 free_info:
0141     kfree(info);
0142
0143     return ret;
0144 }
0145
0146 static void vpd_section_attrib_destroy(struct vpd_section *sec)
0147 {
0148     struct vpd_attrib_info *info;
0149     struct vpd_attrib_info *temp;
0150
0151     list_for_each_entry_safe(info, temp, &sec->attribs, list) {
0152         sysfs_remove_bin_file(sec->kobj, &info->bin_attr);
0153         kfree(info->key);
0154         kfree(info);
0155     }
0156 }
0157
0158 static ssize_t vpd_section_read(struct file *filp, struct kobject *kobp,
0159                 struct bin_attribute *bin_attr, char *buf,
0160                 loff_t pos, size_t count)
0161 {
0162     struct vpd_section *sec = bin_attr->private;
0163
0164     return memory_read_from_buffer(buf, count, &pos, sec->baseaddr,
0165                        sec->bin_attr.size);
0166 }
0167
0168 static int vpd_section_create_attribs(struct vpd_section *sec)
0169 {
0170     s32 consumed;
0171     int ret;
0172
0173     consumed = 0;
0174     do {
0175         ret = vpd_decode_string(sec->bin_attr.size, sec->baseaddr,
0176                     &consumed, vpd_section_attrib_add, sec);
0177     } while (ret == VPD_OK);
0178
0179     return 0;
0180 }
0181
0182 static int vpd_section_init(const char *name, struct vpd_section *sec,
0183                 phys_addr_t physaddr, size_t size)
0184 {
0185     int err;
0186
0187     sec->baseaddr = memremap(physaddr, size, MEMREMAP_WB);
0188     if (!sec->baseaddr)
0189         return -ENOMEM;
0190
0191     sec->name = name;
0192
0193     /* We want to export the raw partition with name ${name}_raw */
0194     sec->raw_name = kasprintf(GFP_KERNEL, "%s_raw", name);
0195     if (!sec->raw_name) {
0196         err = -ENOMEM;
0197         goto err_memunmap;
0198     }
0199
0200     sysfs_bin_attr_init(&sec->bin_attr);
0201     sec->bin_attr.attr.name = sec->raw_name;
0202     sec->bin_attr.attr.mode = 0444;
0203     sec->bin_attr.size = size;
0204     sec->bin_attr.read = vpd_section_read;
0205     sec->bin_attr.private = sec;
0206
0207     err = sysfs_create_bin_file(vpd_kobj, &sec->bin_attr);
0208     if (err)
0209         goto err_free_raw_name;
0210
0211     sec->kobj = kobject_create_and_add(name, vpd_kobj);
0212     if (!sec->kobj) {
0213         err = -EINVAL;
0214         goto err_sysfs_remove;
0215     }
0216
0217     INIT_LIST_HEAD(&sec->attribs);
0218     vpd_section_create_attribs(sec);
0219
0220     sec->enabled = true;
0221
0222     return 0;
0223
0224 err_sysfs_remove:
0225     sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr);
0226 err_free_raw_name:
0227     kfree(sec->raw_name);
0228 err_memunmap:
0229     memunmap(sec->baseaddr);
0230     return err;
0231 }
0232
0233 static int vpd_section_destroy(struct vpd_section *sec)
0234 {
0235     if (sec->enabled) {
0236         vpd_section_attrib_destroy(sec);
0237         kobject_put(sec->kobj);
0238         sysfs_remove_bin_file(vpd_kobj, &sec->bin_attr);
0239         kfree(sec->raw_name);
0240         memunmap(sec->baseaddr);
0241         sec->enabled = false;
0242     }
0243
0244     return 0;
0245 }
0246
0247 static int vpd_sections_init(phys_addr_t physaddr)
0248 {
0249     struct vpd_cbmem *temp;
0250     struct vpd_cbmem header;
0251     int ret = 0;
0252
0253     temp = memremap(physaddr, sizeof(struct vpd_cbmem), MEMREMAP_WB);
0254     if (!temp)
0255         return -ENOMEM;
0256
0257     memcpy(&header, temp, sizeof(struct vpd_cbmem));
0258     memunmap(temp);
0259
0260     if (header.magic != VPD_CBMEM_MAGIC)
0261         return -ENODEV;
0262
0263     if (header.ro_size) {
0264         ret = vpd_section_init("ro", &ro_vpd,
0265                        physaddr + sizeof(struct vpd_cbmem),
0266                        header.ro_size);
0267         if (ret)
0268             return ret;
0269     }
0270
0271     if (header.rw_size) {
0272         ret = vpd_section_init("rw", &rw_vpd,
0273                        physaddr + sizeof(struct vpd_cbmem) +
0274                        header.ro_size, header.rw_size);
0275         if (ret) {
0276             vpd_section_destroy(&ro_vpd);
0277             return ret;
0278         }
0279     }
0280
0281     return 0;
0282 }
0283
0284 static int vpd_probe(struct coreboot_device *dev)
0285 {
0286     int ret;
0287
0288     vpd_kobj = kobject_create_and_add("vpd", firmware_kobj);
0289     if (!vpd_kobj)
0290         return -ENOMEM;
0291
0292     ret = vpd_sections_init(dev->cbmem_ref.cbmem_addr);
0293     if (ret) {
0294         kobject_put(vpd_kobj);
0295         return ret;
0296     }
0297
0298     return 0;
0299 }
0300
0301 static void vpd_remove(struct coreboot_device *dev)
0302 {
0303     vpd_section_destroy(&ro_vpd);
0304     vpd_section_destroy(&rw_vpd);
0305
0306     kobject_put(vpd_kobj);
0307 }
0308
0309 static struct coreboot_driver vpd_driver = {
0310     .probe = vpd_probe,
0311     .remove = vpd_remove,
0312     .drv = {
0313         .name = "vpd",
0314     },
0315     .tag = CB_TAG_VPD,
0316 };
0317 module_coreboot_driver(vpd_driver);
0318
0319 MODULE_AUTHOR("Google, Inc.");
0320 MODULE_LICENSE("GPL");