1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright �� 2022 Rafa�� Mi��ecki <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, 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
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_LICENSE("GPL");
85