Commit 002181f5 authored by Rafał Miłecki's avatar Rafał Miłecki Committed by Miquel Raynal
Browse files

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



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

Signed-off-by: default avatarRafał Miłecki <rafal@milecki.pl>
Signed-off-by: default avatarMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220711153041.6036-2-zajec5@gmail.com
parent 27bfb201

drivers/mtd/parsers/Kconfig

+10 −0
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@@ -20,6 +20,16 @@ config MTD_BCM63XX_PARTS 
	  This provides partition parsing for BCM63xx devices with CFE

	  This provides partition parsing for BCM63xx devices with CFE

	  bootloaders.

	  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

config MTD_CMDLINE_PARTS

	tristate "Command line partition table parsing"

	tristate "Command line partition table parsing"

	depends on MTD

	depends on MTD

drivers/mtd/parsers/Makefile

+1 −0
Original line number Original line Diff line number Diff line
@@ -2,6 +2,7 @@ 
obj-$(CONFIG_MTD_AR7_PARTS)		+= ar7part.o

obj-$(CONFIG_MTD_AR7_PARTS)		+= ar7part.o

obj-$(CONFIG_MTD_BCM47XX_PARTS)		+= bcm47xxpart.o

obj-$(CONFIG_MTD_BCM47XX_PARTS)		+= bcm47xxpart.o

obj-$(CONFIG_MTD_BCM63XX_PARTS)		+= bcm63xxpart.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_CMDLINE_PARTS)		+= cmdlinepart.o

obj-$(CONFIG_MTD_OF_PARTS)		+= ofpart.o

obj-$(CONFIG_MTD_OF_PARTS)		+= ofpart.o

ofpart-y				+= ofpart_core.o

ofpart-y				+= ofpart_core.o

drivers/mtd/parsers/brcm_u-boot.c

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// 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");