--- /dev/null
+/*
+ * MTD splitter for MikroTik NOR devices
+ *
+ * Copyright (C) 2017 Thibaut VARENE <varenet@parisc-linux.org>
+ *
+ * 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.
+ *
+ * The rootfs is expected at erase-block boundary due to the use of
+ * mtd_find_rootfs_from(). We use a trimmed down version of the yaffs header
+ * for two main reasons:
+ * - the original header uses weakly defined types (int, enum...) which can
+ * vary in length depending on build host (and the struct is not packed),
+ * and the name field can have a different total length depending on
+ * whether or not the yaffs code was _built_ with unicode support.
+ * - the only field that could be of real use here (file_size_low) contains
+ * invalid data in the header generated by kernel2minor, so we cannot use
+ * it to infer the exact position of the rootfs and do away with
+ * mtd_find_rootfs_from() (and thus have non-EB-aligned rootfs).
+ */
+
+#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/string.h>
+
+#include "mtdsplit.h"
+
+#define YAFFS_OBJECT_TYPE_FILE 0x1
+#define YAFFS_OBJECTID_ROOT 0x1
+#define YAFFS_SUM_UNUSED 0xFFFF
+#define YAFFS_NAME "kernel"
+
+#define MINOR_NR_PARTS 2
+
+/*
+ * This structure is based on yaffs_obj_hdr from yaffs_guts.h
+ * The weak types match upstream. The fields have cpu-endianness
+ */
+struct minor_header {
+ int yaffs_type;
+ int yaffs_obj_id;
+ u16 yaffs_sum_unused;
+ char yaffs_name[sizeof(YAFFS_NAME)];
+};
+
+static int mtdsplit_parse_minor(struct mtd_info *master,
+ const struct mtd_partition **pparts,
+ struct mtd_part_parser_data *data)
+{
+ struct minor_header hdr;
+ size_t hdr_len, retlen;
+ size_t rootfs_offset;
+ struct mtd_partition *parts;
+ int err;
+
+ hdr_len = sizeof(hdr);
+ err = mtd_read(master, 0, hdr_len, &retlen, (void *) &hdr);
+ if (err)
+ return err;
+
+ if (retlen != hdr_len)
+ return -EIO;
+
+ /* match header */
+ if (hdr.yaffs_type != YAFFS_OBJECT_TYPE_FILE)
+ return -EINVAL;
+
+ if (hdr.yaffs_obj_id != YAFFS_OBJECTID_ROOT)
+ return -EINVAL;
+
+ if (hdr.yaffs_sum_unused != YAFFS_SUM_UNUSED)
+ return -EINVAL;
+
+ if (memcmp(hdr.yaffs_name, YAFFS_NAME, sizeof(YAFFS_NAME)))
+ return -EINVAL;
+
+ err = mtd_find_rootfs_from(master, master->erasesize, master->size,
+ &rootfs_offset, NULL);
+ if (err)
+ return err;
+
+ parts = kzalloc(MINOR_NR_PARTS * sizeof(*parts), GFP_KERNEL);
+ if (!parts)
+ return -ENOMEM;
+
+ parts[0].name = KERNEL_PART_NAME;
+ parts[0].offset = 0;
+ parts[0].size = rootfs_offset;
+
+ parts[1].name = ROOTFS_PART_NAME;
+ parts[1].offset = rootfs_offset;
+ parts[1].size = master->size - rootfs_offset;
+
+ *pparts = parts;
+ return MINOR_NR_PARTS;
+}
+
+static struct mtd_part_parser mtdsplit_minor_parser = {
+ .owner = THIS_MODULE,
+ .name = "minor-fw",
+ .parse_fn = mtdsplit_parse_minor,
+ .type = MTD_PARSER_TYPE_FIRMWARE,
+};
+
+static int __init mtdsplit_minor_init(void)
+{
+ register_mtd_parser(&mtdsplit_minor_parser);
+
+ return 0;
+}
+
+subsys_initcall(mtdsplit_minor_init);
projects / openwrt / staging / jow.git / commitdiff