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mtd: parsers: add Broadcom's U-Boot parser

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Broadcom stores environment variables blocks inside U-Boot partition
itself. This driver finds & registers them.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220711153041.6036-2-zajec5@gmail.com
This commit is contained in:
Rafał Miłecki 2022-07-11 17:30:41 +02:00 committed by Miquel Raynal
parent 27bfb201b2
commit 002181f5b1
3 changed files with 95 additions and 0 deletions
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10
drivers/mtd/parsers/Kconfig
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@ -20,6 +20,16 @@ config MTD_BCM63XX_PARTS
This provides partition parsing for BCM63xx devices with CFE
bootloaders.
config MTD_BRCM_U_BOOT
tristate "Broadcom's U-Boot partition parser"
depends on ARCH_BCM4908 || COMPILE_TEST
help
Broadcom uses a custom way of storing U-Boot environment variables.
They are placed inside U-Boot partition itself at unspecified offset.
It's possible to locate them by looking for a custom header with a
magic value. This driver does that and creates subpartitions for
each found environment variables block.
config MTD_CMDLINE_PARTS
tristate "Command line partition table parsing"
depends on MTD

1
drivers/mtd/parsers/Makefile
View File

@ -2,6 +2,7 @@
obj-$(CONFIG_MTD_AR7_PARTS) += ar7part.o
obj-$(CONFIG_MTD_BCM47XX_PARTS) += bcm47xxpart.o
obj-$(CONFIG_MTD_BCM63XX_PARTS) += bcm63xxpart.o
obj-$(CONFIG_MTD_BRCM_U_BOOT) += brcm_u-boot.o
obj-$(CONFIG_MTD_CMDLINE_PARTS) += cmdlinepart.o
obj-$(CONFIG_MTD_OF_PARTS) += ofpart.o
ofpart-y += ofpart_core.o

84
drivers/mtd/parsers/brcm_u-boot.c Normal file
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@ -0,0 +1,84 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright © 2022 Rafał Miłecki <rafal@milecki.pl>
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#define BRCM_U_BOOT_MAX_OFFSET 0x200000
#define BRCM_U_BOOT_STEP 0x1000
#define BRCM_U_BOOT_MAX_PARTS 2
#define BRCM_U_BOOT_MAGIC 0x75456e76 /* uEnv */
struct brcm_u_boot_header {
__le32 magic;
__le32 length;
} __packed;
static const char *names[BRCM_U_BOOT_MAX_PARTS] = {
"u-boot-env",
"u-boot-env-backup",
};
static int brcm_u_boot_parse(struct mtd_info *mtd,
const struct mtd_partition **pparts,
struct mtd_part_parser_data *data)
{
struct brcm_u_boot_header header;
struct mtd_partition *parts;
size_t bytes_read;
size_t offset;
int err;
int i = 0;
parts = kcalloc(BRCM_U_BOOT_MAX_PARTS, sizeof(*parts), GFP_KERNEL);
if (!parts)
return -ENOMEM;
for (offset = 0;
offset < min_t(size_t, mtd->size, BRCM_U_BOOT_MAX_OFFSET);
offset += BRCM_U_BOOT_STEP) {
err = mtd_read(mtd, offset, sizeof(header), &bytes_read, (uint8_t *)&header);
if (err && !mtd_is_bitflip(err)) {
pr_err("Failed to read from %s at 0x%zx: %d\n", mtd->name, offset, err);
continue;
}
if (le32_to_cpu(header.magic) != BRCM_U_BOOT_MAGIC)
continue;
parts[i].name = names[i];
parts[i].offset = offset;
parts[i].size = sizeof(header) + le32_to_cpu(header.length);
i++;
pr_info("offset:0x%zx magic:0x%08x BINGO\n", offset, header.magic);
if (i == BRCM_U_BOOT_MAX_PARTS)
break;
}
*pparts = parts;
return i;
};
static const struct of_device_id brcm_u_boot_of_match_table[] = {
{ .compatible = "brcm,u-boot" },
{},
};
MODULE_DEVICE_TABLE(of, brcm_u_boot_of_match_table);
static struct mtd_part_parser brcm_u_boot_mtd_parser = {
.parse_fn = brcm_u_boot_parse,
.name = "brcm_u-boot",
.of_match_table = brcm_u_boot_of_match_table,
};
module_mtd_part_parser(brcm_u_boot_mtd_parser);
MODULE_LICENSE("GPL");