From: Rafał Miłecki <rafal@xxxxxxxxxx>
Broadcom stores environment variables blocks inside U-Boot partition
itself. This driver finds & registers them.
Signed-off-by: Rafał Miłecki <rafal@xxxxxxxxxx>
---
drivers/mtd/parsers/Kconfig | 10 ++++
drivers/mtd/parsers/Makefile | 1 +
drivers/mtd/parsers/brcm_u-boot.c | 84 +++++++++++++++++++++++++++++++
3 files changed, 95 insertions(+)
create mode 100644 drivers/mtd/parsers/brcm_u-boot.c
diff --git a/drivers/mtd/parsers/Kconfig b/drivers/mtd/parsers/Kconfig
index b43df73927a0..81f2d0a795a6 100644
--- a/drivers/mtd/parsers/Kconfig
+++ b/drivers/mtd/parsers/Kconfig
@@ -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
diff --git a/drivers/mtd/parsers/Makefile b/drivers/mtd/parsers/Makefile
index 2fcf0ab9e7da..23fa4de4016f 100644
--- a/drivers/mtd/parsers/Makefile
+++ b/drivers/mtd/parsers/Makefile
@@ -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
diff --git a/drivers/mtd/parsers/brcm_u-boot.c b/drivers/mtd/parsers/brcm_u-boot.c
new file mode 100644
index 000000000000..7c338dc7b8f3
--- /dev/null
+++ b/drivers/mtd/parsers/brcm_u-boot.c
@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright © 2022 Rafał Miłecki <rafal@xxxxxxxxxx>
+ */
+
+#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");
--
2.34.1
