kernel: mtdsplit: add support for BCM63XX CFE firmware

Broadcom CFE bootloader relies on a tag for identifying the current firmware,
such as version, image start address, kernel address and size, rootfs size,
board id, signatures, etc.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

target/linux/generic/config-5.10

@@ -3525,6 +3525,7 @@ CONFIG_MTD_ROOTFS_ROOT_DEV=y
 # CONFIG_MTD_SPI_NOR_USE_4K_SECTORS is not set
 CONFIG_MTD_SPI_NOR_USE_4K_SECTORS_LIMIT=4096
 CONFIG_MTD_SPLIT=y
+# CONFIG_MTD_SPLIT_BCM63XX_FW is not set
 # CONFIG_MTD_SPLIT_BCM_WFI_FW is not set
 # CONFIG_MTD_SPLIT_BRNIMAGE_FW is not set
 # CONFIG_MTD_SPLIT_ELF_FW is not set

target/linux/generic/config-5.4

@@ -3249,6 +3249,7 @@ CONFIG_MTD_ROOTFS_ROOT_DEV=y
 # CONFIG_MTD_SPI_NOR_USE_4K_SECTORS is not set
 CONFIG_MTD_SPI_NOR_USE_4K_SECTORS_LIMIT=4096
 CONFIG_MTD_SPLIT=y
+# CONFIG_MTD_SPLIT_BCM63XX_FW is not set
 # CONFIG_MTD_SPLIT_BCM_WFI_FW is not set
 # CONFIG_MTD_SPLIT_BRNIMAGE_FW is not set
 # CONFIG_MTD_SPLIT_ELF_FW is not set

target/linux/generic/files/drivers/mtd/mtdsplit/Kconfig

@@ -20,6 +20,11 @@ config MTD_SPLIT_SQUASHFS_ROOT
 
 comment "Firmware partition parsers"
 
+config MTD_SPLIT_BCM63XX_FW
+	bool "BCM63xx firmware parser"
+	depends on MTD_SPLIT_SUPPORT
+	select MTD_SPLIT
+
 config MTD_SPLIT_BCM_WFI_FW
 	bool "Broadcom Whole Flash Image parser"
 	depends on MTD_SPLIT_SUPPORT

target/linux/generic/files/drivers/mtd/mtdsplit/Makefile

@@ -1,4 +1,5 @@
 obj-$(CONFIG_MTD_SPLIT)		+= mtdsplit.o
+obj-$(CONFIG_MTD_SPLIT_BCM63XX_FW) += mtdsplit_bcm63xx.o
 obj-$(CONFIG_MTD_SPLIT_BCM_WFI_FW) += mtdsplit_bcm_wfi.o
 obj-$(CONFIG_MTD_SPLIT_CFE_BOOTFS) += mtdsplit_cfe_bootfs.o
 obj-$(CONFIG_MTD_SPLIT_SEAMA_FW) += mtdsplit_seama.o

target/linux/generic/files/drivers/mtd/mtdsplit/mtdsplit_bcm63xx.c

@@ -0,0 +1,186 @@
+/*
+ * Firmware MTD split for BCM63XX, based on bcm63xxpart.c
+ *
+ * Copyright (C) 2006-2008 Florian Fainelli <florian@openwrt.org>
+ * Copyright (C) 2006-2008 Mike Albon <malbon@openwrt.org>
+ * Copyright (C) 2009-2010 Daniel Dickinson <openwrt@cshore.neomailbox.net>
+ * Copyright (C) 2011-2013 Jonas Gorski <jonas.gorski@gmail.com>
+ * Copyright (C) 2015 Simon Arlott <simon@fire.lp0.eu>
+ * Copyright (C) 2017 Álvaro Fernández Rojas <noltari@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/bcm963xx_tag.h>
+#include <linux/crc32.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/byteorder/generic.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+
+#include "mtdsplit.h"
+
+/* Ensure strings read from flash structs are null terminated */
+#define STR_NULL_TERMINATE(x) \
+	do { char *_str = (x); _str[sizeof(x) - 1] = 0; } while (0)
+
+#define BCM63XX_NR_PARTS 2
+
+static int bcm63xx_read_image_tag(struct mtd_info *master, loff_t offset,
+				  struct bcm_tag *hdr)
+{
+	int ret;
+	size_t retlen;
+	u32 computed_crc;
+
+	ret = mtd_read(master, offset, sizeof(*hdr), &retlen, (void *) hdr);
+	if (ret)
+		return ret;
+
+	if (retlen != sizeof(*hdr))
+		return -EIO;
+
+	computed_crc = crc32_le(IMAGETAG_CRC_START, (u8 *)hdr,
+				offsetof(struct bcm_tag, header_crc));
+	if (computed_crc == hdr->header_crc) {
+	    STR_NULL_TERMINATE(hdr->board_id);
+	    STR_NULL_TERMINATE(hdr->tag_version);
+
+		pr_info("CFE image tag found at 0x%llx with version %s, "
+			"board type %s\n", offset, hdr->tag_version,
+			hdr->board_id);
+
+		return 0;
+	} else {
+		pr_err("CFE image tag at 0x%llx CRC invalid "
+		       "(expected %08x, actual %08x)\n",
+		       offset, hdr->header_crc, computed_crc);
+
+		return 1;
+	}
+}
+
+static int bcm63xx_parse_partitions(struct mtd_info *master,
+				    const struct mtd_partition **pparts,
+				    struct bcm_tag *hdr)
+{
+	struct mtd_partition *parts;
+	unsigned int flash_image_start;
+	unsigned int kernel_address;
+	unsigned int kernel_length;
+	size_t kernel_offset = 0, kernel_size = 0;
+	size_t rootfs_offset = 0, rootfs_size = 0;
+	int kernel_part, rootfs_part;
+
+	STR_NULL_TERMINATE(hdr->flash_image_start);
+	if (kstrtouint(hdr->flash_image_start, 10, &flash_image_start) ||
+	    flash_image_start < BCM963XX_EXTENDED_SIZE) {
+		pr_err("invalid rootfs address: %*ph\n",
+		       (int) sizeof(hdr->flash_image_start),
+		       hdr->flash_image_start);
+		return -EINVAL;
+	}
+
+	STR_NULL_TERMINATE(hdr->kernel_address);
+	if (kstrtouint(hdr->kernel_address, 10, &kernel_address) ||
+	    kernel_address < BCM963XX_EXTENDED_SIZE) {
+		pr_err("invalid kernel address: %*ph\n",
+		       (int) sizeof(hdr->kernel_address), hdr->kernel_address);
+		return -EINVAL;
+	}
+
+	STR_NULL_TERMINATE(hdr->kernel_length);
+	if (kstrtouint(hdr->kernel_length, 10, &kernel_length) ||
+	    !kernel_length) {
+		pr_err("invalid kernel length: %*ph\n",
+		       (int) sizeof(hdr->kernel_length), hdr->kernel_length);
+		return -EINVAL;
+	}
+
+	kernel_offset = kernel_address - BCM963XX_EXTENDED_SIZE -
+			mtdpart_get_offset(master);
+	kernel_size = kernel_length;
+
+	if (flash_image_start < kernel_address) {
+		/* rootfs first */
+		rootfs_part = 0;
+		kernel_part = 1;
+		rootfs_offset = flash_image_start - BCM963XX_EXTENDED_SIZE -
+				mtdpart_get_offset(master);
+		rootfs_size = kernel_offset - rootfs_offset;
+	} else {
+		/* kernel first */
+		kernel_part = 0;
+		rootfs_part = 1;
+		rootfs_offset = kernel_offset + kernel_size;
+		rootfs_size = master->size - rootfs_offset;
+	}
+
+	if (mtd_check_rootfs_magic(master, rootfs_offset, NULL))
+		pr_warn("rootfs magic not found\n");
+
+	parts = kzalloc(BCM63XX_NR_PARTS * sizeof(*parts), GFP_KERNEL);
+	if (!parts)
+		return -ENOMEM;
+
+	parts[kernel_part].name = KERNEL_PART_NAME;
+	parts[kernel_part].offset = kernel_offset;
+	parts[kernel_part].size = kernel_size;
+
+	parts[rootfs_part].name = ROOTFS_PART_NAME;
+	parts[rootfs_part].offset = rootfs_offset;
+	parts[rootfs_part].size = rootfs_size;
+
+	*pparts = parts;
+	return BCM63XX_NR_PARTS;
+}
+
+static int mtdsplit_parse_bcm63xx(struct mtd_info *master,
+				  const struct mtd_partition **pparts,
+				  struct mtd_part_parser_data *data)
+{
+	struct bcm_tag hdr;
+	loff_t offset;
+
+	if (mtd_type_is_nand(master))
+		return -EINVAL;
+
+	/* find bcm63xx_cfe image on erase block boundaries */
+	for (offset = 0; offset < master->size; offset += master->erasesize) {
+		if (!bcm63xx_read_image_tag(master, offset, (void *) &hdr))
+			return bcm63xx_parse_partitions(master, pparts,
+							(void *) &hdr);
+	}
+
+	return -EINVAL;
+}
+
+static const struct of_device_id mtdsplit_fit_of_match_table[] = {
+	{ .compatible = "brcm,bcm963xx-imagetag" },
+	{ },
+};
+
+static struct mtd_part_parser mtdsplit_bcm63xx_parser = {
+	.owner = THIS_MODULE,
+	.name = "bcm63xx-fw",
+	.of_match_table = mtdsplit_fit_of_match_table,
+	.parse_fn = mtdsplit_parse_bcm63xx,
+	.type = MTD_PARSER_TYPE_FIRMWARE,
+};
+
+static int __init mtdsplit_bcm63xx_init(void)
+{
+	register_mtd_parser(&mtdsplit_bcm63xx_parser);
+
+	return 0;
+}
+
+module_init(mtdsplit_bcm63xx_init);