drivers/mtd/parsers/brcm_u-boot.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright © 2022 Rafał Miłecki <rafal@milecki.pl>
   4  */
   5
   6 #include <linux/module.h>
   7 #include <linux/kernel.h>
   8 #include <linux/slab.h>
   9 #include <linux/mtd/mtd.h>
  10 #include <linux/mtd/partitions.h>
  11
  12 #define BRCM_U_BOOT_MAX_OFFSET          0x200000
  13 #define BRCM_U_BOOT_STEP                0x1000
  14
  15 #define BRCM_U_BOOT_MAX_PARTS           2
  16
  17 #define BRCM_U_BOOT_MAGIC               0x75456e76      /* uEnv */
  18
  19 struct brcm_u_boot_header {
  20         __le32 magic;
  21         __le32 length;
  22 } __packed;
  23
  24 static const char *names[BRCM_U_BOOT_MAX_PARTS] = {
  25         "u-boot-env",
  26         "u-boot-env-backup",
  27 };
  28
  29 static int brcm_u_boot_parse(struct mtd_info *mtd,
  30                              const struct mtd_partition **pparts,
  31                              struct mtd_part_parser_data *data)
  32 {
  33         struct brcm_u_boot_header header;
  34         struct mtd_partition *parts;
  35         size_t bytes_read;
  36         size_t offset;
  37         int err;
  38         int i = 0;
  39
  40         parts = kcalloc(BRCM_U_BOOT_MAX_PARTS, sizeof(*parts), GFP_KERNEL);
  41         if (!parts)
  42                 return -ENOMEM;
  43
  44         for (offset = 0;
  45              offset < min_t(size_t, mtd->size, BRCM_U_BOOT_MAX_OFFSET);
  46              offset += BRCM_U_BOOT_STEP) {
  47                 err = mtd_read(mtd, offset, sizeof(header), &bytes_read, (uint8_t *)&header);
  48                 if (err && !mtd_is_bitflip(err)) {
  49                         pr_err("Failed to read from %s at 0x%zx: %d\n", mtd->name, offset, err);
  50                         continue;
  51                 }
  52
  53                 if (le32_to_cpu(header.magic) != BRCM_U_BOOT_MAGIC)
  54                         continue;
  55
  56                 parts[i].name = names[i];
  57                 parts[i].offset = offset;
  58                 parts[i].size = sizeof(header) + le32_to_cpu(header.length);
  59                 i++;
  60                 pr_info("offset:0x%zx magic:0x%08x BINGO\n", offset, header.magic);
  61
  62                 if (i == BRCM_U_BOOT_MAX_PARTS)
  63                         break;
  64         }
  65
  66         *pparts = parts;
  67
  68         return i;
  69 };
  70
  71 static const struct of_device_id brcm_u_boot_of_match_table[] = {
  72         { .compatible = "brcm,u-boot" },
  73         {},
  74 };
  75 MODULE_DEVICE_TABLE(of, brcm_u_boot_of_match_table);
  76
  77 static struct mtd_part_parser brcm_u_boot_mtd_parser = {
  78         .parse_fn = brcm_u_boot_parse,
  79         .name = "brcm_u-boot",
  80         .of_match_table = brcm_u_boot_of_match_table,
  81 };
  82 module_mtd_part_parser(brcm_u_boot_mtd_parser);
  83
  84 MODULE_DESCRIPTION("Broadcom's U-Boot partition parser");
  85 MODULE_LICENSE("GPL");