[PATCH 1/2] dt-bindings: mtd: partitions: add binding for U-Boot bootloader

[PATCH 1/2] dt-bindings: mtd: partitions: add binding for U-Boot bootloader

[Rafał Miłecki]

From: Rafał Miłecki <rafal@milecki.pl>

Right now there is no (known) real reason for a custom binding for
standard U-Boot partitions. Broadcom's U-Boot however requires extra
handling - looking for environment variables subblocks. This commit adds
Broadcom specific binding.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
 .../bindings/mtd/partitions/u-boot.yaml       | 49 +++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mtd/partitions/u-boot.yaml

diff --git a/Documentation/devicetree/bindings/mtd/partitions/u-boot.yaml b/Documentation/devicetree/bindings/mtd/partitions/u-boot.yaml
new file mode 100644
index 000000000000..8a88e7d16524
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/partitions/u-boot.yaml
@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mtd/partitions/u-boot.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: U-Boot bootloader partition
+
+description: |
+  U-Boot is a bootlodaer commonly used in embedded devices. It's almost always
+  located on some kind of flash device.
+
+  Device configuration is stored as a set of environment variables that are
+  located in a (usually standalone) block of data.
+
+maintainers:
+  - Rafał Miłecki <rafal@milecki.pl>
+
+allOf:
+  - $ref: partition.yaml#
+
+properties:
+  compatible:
+    oneOf:
+      - const: brcm,u-boot
+        description: |
+          Broadcom stores environment variables inside a U-Boot partition. They
+          can be identified by a custom header with magic value.
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    partitions {
+        compatible = "fixed-partitions";
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        partition@0 {
+            compatible = "brcm,u-boot";
+            reg = <0x0 0x100000>;
+            label = "u-boot";
+        };
+
+        partition@100000 {
+            reg = <0x100000 0x1ff00000>;
+            label = "firmware";
+        };
+    };
-- 
2.34.1


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[PATCH 2/2] mtd: parsers: add Broadcom's U-Boot parser

[Rafał Miłecki]

From: Rafał Miłecki <rafal@milecki.pl>

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

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
 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@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");
-- 
2.34.1


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Re: [PATCH 1/2] dt-bindings: mtd: partitions: add binding for U-Boot bootloader

[Rob Herring]

On Mon, 11 Jul 2022 17:30:40 +0200, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@milecki.pl>
> 
> Right now there is no (known) real reason for a custom binding for
> standard U-Boot partitions. Broadcom's U-Boot however requires extra
> handling - looking for environment variables subblocks. This commit adds
> Broadcom specific binding.
> 
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> ---
>  .../bindings/mtd/partitions/u-boot.yaml       | 49 +++++++++++++++++++
>  1 file changed, 49 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mtd/partitions/u-boot.yaml
> 

Reviewed-by: Rob Herring <robh@kernel.org>

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Re: [PATCH 2/2] mtd: parsers: add Broadcom's U-Boot parser

[Miquel Raynal]

On Mon, 2022-07-11 at 15:30:41 UTC, =?utf-8?b?UmFmYcWCIE1pxYJlY2tp?= wrote:
> From: Rafał Miłecki <rafal@milecki.pl>
> 
> Broadcom stores environment variables blocks inside U-Boot partition
> itself. This driver finds & registers them.
> 
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.

Miquel

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Re: [PATCH 1/2] dt-bindings: mtd: partitions: add binding for U-Boot bootloader

[Miquel Raynal]

On Mon, 2022-07-11 at 15:30:40 UTC, =?utf-8?b?UmFmYcWCIE1pxYJlY2tp?= wrote:
> From: Rafał Miłecki <rafal@milecki.pl>
> 
> Right now there is no (known) real reason for a custom binding for
> standard U-Boot partitions. Broadcom's U-Boot however requires extra
> handling - looking for environment variables subblocks. This commit adds
> Broadcom specific binding.
> 
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> Reviewed-by: Rob Herring <robh@kernel.org>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.

Miquel

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