| /* |
| * 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 <linux/of.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 const struct of_device_id mtdsplit_minor_of_match_table[] = { |
| { .compatible = "mikrotik,minor" }, |
| {}, |
| }; |
| MODULE_DEVICE_TABLE(of, mtdsplit_minor_of_match_table); |
| |
| static struct mtd_part_parser mtdsplit_minor_parser = { |
| .owner = THIS_MODULE, |
| .name = "minor-fw", |
| .of_match_table = mtdsplit_minor_of_match_table, |
| .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); |