kernel: mtdsplit: add support for brnImages

[openwrt.git] / target / linux / generic / files / drivers / mtd / mtdsplit / mtdsplit_brnimage.c

diff --git a/target/linux/generic/files/drivers/mtd/mtdsplit/mtdsplit_brnimage.c b/target/linux/generic/files/drivers/mtd/mtdsplit/mtdsplit_brnimage.c
new file mode 100644 (file)
index 0000000..7ddd69b
--- /dev/null
+++ b/target/linux/generic/files/drivers/mtd/mtdsplit/mtdsplit_brnimage.c
@@ -0,0 +1,104 @@
+/*
+ *  Copyright (C) 2012 John Crispin <blogic@openwrt.org>
+ *  Copyright (C) 2015 Martin Blumenstingl <martin.blumenstingl@googlemail.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.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+#include <linux/byteorder/generic.h>
+
+#include "mtdsplit.h"
+
+#define BRNIMAGE_NR_PARTS      2
+
+#define BRNIMAGE_ALIGN_BYTES   0x400
+#define BRNIMAGE_FOOTER_SIZE   12
+
+#define BRNIMAGE_MIN_OVERHEAD  (BRNIMAGE_FOOTER_SIZE)
+#define BRNIMAGE_MAX_OVERHEAD  (BRNIMAGE_ALIGN_BYTES + BRNIMAGE_FOOTER_SIZE)
+
+static int mtdsplit_parse_brnimage(struct mtd_info *master,
+                               struct mtd_partition **pparts,
+                               struct mtd_part_parser_data *data)
+{
+       struct mtd_partition *parts;
+       uint32_t buf;
+       unsigned long rootfs_offset, rootfs_size, kernel_size;
+       size_t len;
+       int ret;
+
+       for (rootfs_offset = 0; rootfs_offset < master->size;
+            rootfs_offset += BRNIMAGE_ALIGN_BYTES) {
+               ret = mtd_check_rootfs_magic(master, rootfs_offset);
+               if (!ret)
+                       break;
+       }
+
+       if (ret)
+               return ret;
+
+       if (rootfs_offset >= master->size)
+               return -EINVAL;
+
+       ret = mtd_read(master, rootfs_offset - BRNIMAGE_FOOTER_SIZE, 4, &len,
+                       (void *)&buf);
+       if (ret)
+               return ret;
+
+       if (len != 4)
+               return -EIO;
+
+       kernel_size = le32_to_cpu(buf);
+
+       if (kernel_size > (rootfs_offset - BRNIMAGE_MIN_OVERHEAD))
+               return -EINVAL;
+
+       if (kernel_size < (rootfs_offset - BRNIMAGE_MAX_OVERHEAD))
+               return -EINVAL;
+
+       /*
+        * The footer must be untouched as it contains the checksum of the
+        * original brnImage (kernel + squashfs)!
+        */
+       rootfs_size = master->size - rootfs_offset - BRNIMAGE_FOOTER_SIZE;
+
+       parts = kzalloc(BRNIMAGE_NR_PARTS * sizeof(*parts), GFP_KERNEL);
+       if (!parts)
+               return -ENOMEM;
+
+       parts[0].name = KERNEL_PART_NAME;
+       parts[0].offset = 0;
+       parts[0].size = kernel_size;
+
+       parts[1].name = ROOTFS_PART_NAME;
+       parts[1].offset = rootfs_offset;
+       parts[1].size = rootfs_size;
+
+       *pparts = parts;
+       return BRNIMAGE_NR_PARTS;
+}
+
+static struct mtd_part_parser mtdsplit_brnimage_parser = {
+       .owner = THIS_MODULE,
+       .name = "brnimage-fw",
+       .parse_fn = mtdsplit_parse_brnimage,
+       .type = MTD_PARSER_TYPE_FIRMWARE,
+};
+
+static int __init mtdsplit_brnimage_init(void)
+{
+       register_mtd_parser(&mtdsplit_brnimage_parser);
+
+       return 0;
+}
+
+subsys_initcall(mtdsplit_brnimage_init);