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
19struct brcm_u_boot_header {
20 __le32 magic;
21 __le32 length;
22} __packed;
23
24static const char *names[BRCM_U_BOOT_MAX_PARTS] = {
25 "u-boot-env",
26 "u-boot-env-backup",
27};
28
29static 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, from: offset, len: sizeof(header), retlen: &bytes_read, buf: (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
71static const struct of_device_id brcm_u_boot_of_match_table[] = {
72 { .compatible = "brcm,u-boot" },
73 {},
74};
75MODULE_DEVICE_TABLE(of, brcm_u_boot_of_match_table);
76
77static 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};
82module_mtd_part_parser(brcm_u_boot_mtd_parser);
83
84MODULE_DESCRIPTION("Broadcom's U-Boot partition parser");
85MODULE_LICENSE("GPL");
86

source code of linux/drivers/mtd/parsers/brcm_u-boot.c