kernel: move mediatek BMT support patch to generic patches

Preparation for supporting BMT on MT7621. Move source files to the files/
subdirectory in order to simplify maintenance

Signed-off-by: Felix Fietkau <nbd@nbd.name>

4 files changed, 830 insertions, 0 deletions

diff --git a/target/linux/generic/config-5.10 b/target/linux/generic/config-5.10
index 714a0b9ec7..c9e44e11c2 100644
--- a/target/linux/generic/config-5.10
+++ b/target/linux/generic/config-5.10
@@ -3669,6 +3669,7 @@ CONFIG_MTD_SPLIT_SUPPORT=y
 # CONFIG_MTD_UBI_GLUEBI is not set
 # CONFIG_MTD_UIMAGE_SPLIT is not set
 # CONFIG_MTD_VIRT_CONCAT is not set
+# CONFIG_MTD_NAND_MTK_BMT is not set
 # CONFIG_MTK_MMC is not set
 # CONFIG_MTK_MMSYS is not set
 CONFIG_MULTIUSER=y
diff --git a/target/linux/generic/files/drivers/mtd/nand/mtk_bmt.c b/target/linux/generic/files/drivers/mtd/nand/mtk_bmt.c
new file mode 100644
index 0000000000..f249f571c4
--- /dev/null
+++ b/target/linux/generic/files/drivers/mtd/nand/mtk_bmt.c
@@ -0,0 +1,788 @@
+/*
+ * Copyright (c) 2017 MediaTek Inc.
+ * Author: Xiangsheng Hou <xiangsheng.hou@mediatek.com>
+ * Copyright (c) 2020 Felix Fietkau <nbd@nbd.name>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/slab.h>
+#include <linux/gfp.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+#include <linux/mtd/mtk_bmt.h>
+#include <linux/module.h>
+#include <linux/debugfs.h>
+
+#define MAIN_SIGNATURE_OFFSET   0
+#define OOB_SIGNATURE_OFFSET    1
+#define BBPOOL_RATIO		2
+
+#define BBT_LOG(fmt, ...) pr_debug("[BBT][%s|%d] "fmt"\n", __func__, __LINE__, ##__VA_ARGS__)
+
+/* Maximum 8k blocks */
+#define BB_TABLE_MAX	bmtd.table_size
+#define BMT_TABLE_MAX	(BB_TABLE_MAX * BBPOOL_RATIO / 100)
+#define BMT_TBL_DEF_VAL	0x0
+
+/*
+ * Burner Bad Block Table
+ * --------- Only support SLC Nand Chips!!!!!!!!!!! ----------
+ */
+
+struct bbbt {
+	char signature[3];
+	/* This version is used to distinguish the legacy and new algorithm */
+#define BBMT_VERSION		2
+	unsigned char version;
+	/* Below 2 tables will be written in SLC */
+	u16 bb_tbl[];
+};
+
+struct bbmt {
+	u16 block;
+#define NO_MAPPED		0
+#define NORMAL_MAPPED	1
+#define BMT_MAPPED		2
+	u16 mapped;
+};
+
+static struct bmt_desc {
+	struct mtd_info *mtd;
+
+	int (*_read_oob) (struct mtd_info *mtd, loff_t from,
+			  struct mtd_oob_ops *ops);
+	int (*_write_oob) (struct mtd_info *mtd, loff_t to,
+			   struct mtd_oob_ops *ops);
+	int (*_erase) (struct mtd_info *mtd, struct erase_info *instr);
+	int (*_block_isbad) (struct mtd_info *mtd, loff_t ofs);
+	int (*_block_markbad) (struct mtd_info *mtd, loff_t ofs);
+
+	struct bbbt *bbt;
+
+	struct dentry *debugfs_dir;
+
+	u32 table_size;
+	u32 pg_size;
+	u32 blk_size;
+	u16 pg_shift;
+	u16 blk_shift;
+	/* bbt logical address */
+	u16 pool_lba;
+	/* bbt physical address */
+	u16 pool_pba;
+	/* Maximum count of bad blocks that the vendor guaranteed */
+	u16 bb_max;
+	/* Total blocks of the Nand Chip */
+	u16 total_blks;
+	/* The block(n) BMT is located at (bmt_tbl[n]) */
+	u16 bmt_blk_idx;
+	/* How many pages needs to store 'struct bbbt' */
+	u32 bmt_pgs;
+
+	/* to compensate for driver level remapping */
+	u8 oob_offset;
+} bmtd = {0};
+
+static unsigned char *nand_bbt_buf;
+static unsigned char *nand_data_buf;
+
+/* -------- Unit conversions -------- */
+static inline u32 blk_pg(u16 block)
+{
+	return (u32)(block << (bmtd.blk_shift - bmtd.pg_shift));
+}
+
+/* -------- Nand operations wrapper -------- */
+static inline int
+bbt_nand_read(u32 page, unsigned char *dat, int dat_len,
+	      unsigned char *fdm, int fdm_len)
+{
+	struct mtd_oob_ops ops = {
+		.mode = MTD_OPS_PLACE_OOB,
+		.ooboffs = bmtd.oob_offset,
+		.oobbuf = fdm,
+		.ooblen = fdm_len,
+		.datbuf = dat,
+		.len = dat_len,
+	};
+
+	return bmtd._read_oob(bmtd.mtd, page << bmtd.pg_shift, &ops);
+}
+
+static inline int bbt_nand_erase(u16 block)
+{
+	struct mtd_info *mtd = bmtd.mtd;
+	struct erase_info instr = {
+		.addr = (loff_t)block << bmtd.blk_shift,
+		.len = bmtd.blk_size,
+	};
+
+	return bmtd._erase(mtd, &instr);
+}
+
+/* -------- Bad Blocks Management -------- */
+static inline struct bbmt *bmt_tbl(struct bbbt *bbbt)
+{
+	return (struct bbmt *)&bbbt->bb_tbl[bmtd.table_size];
+}
+
+static int
+read_bmt(u16 block, unsigned char *dat, unsigned char *fdm, int fdm_len)
+{
+	u32 len = bmtd.bmt_pgs << bmtd.pg_shift;
+
+	return bbt_nand_read(blk_pg(block), dat, len, fdm, fdm_len);
+}
+
+static int write_bmt(u16 block, unsigned char *dat)
+{
+	struct mtd_oob_ops ops = {
+		.mode = MTD_OPS_PLACE_OOB,
+		.ooboffs = OOB_SIGNATURE_OFFSET + bmtd.oob_offset,
+		.oobbuf = "bmt",
+		.ooblen = 3,
+		.datbuf = dat,
+		.len = bmtd.bmt_pgs << bmtd.pg_shift,
+	};
+	loff_t addr = (loff_t)block << bmtd.blk_shift;
+
+	return bmtd._write_oob(bmtd.mtd, addr, &ops);
+}
+
+static u16 find_valid_block(u16 block)
+{
+	u8 fdm[4];
+	int ret;
+	int loop = 0;
+
+retry:
+	if (block >= bmtd.total_blks)
+		return 0;
+
+	ret = bbt_nand_read(blk_pg(block), nand_data_buf, bmtd.pg_size,
+			    fdm, sizeof(fdm));
+	/* Read the 1st byte of FDM to judge whether it's a bad
+	 * or not
+	 */
+	if (ret || fdm[0] != 0xff) {
+		pr_info("nand: found bad block 0x%x\n", block);
+		if (loop >= bmtd.bb_max) {
+			pr_info("nand: FATAL ERR: too many bad blocks!!\n");
+			return 0;
+		}
+
+		loop++;
+		block++;
+		goto retry;
+	}
+
+	return block;
+}
+
+/* Find out all bad blocks, and fill in the mapping table */
+static int scan_bad_blocks(struct bbbt *bbt)
+{
+	int i;
+	u16 block = 0;
+
+	/* First time download, the block0 MUST NOT be a bad block,
+	 * this is guaranteed by vendor
+	 */
+	bbt->bb_tbl[0] = 0;
+
+	/*
+	 * Construct the mapping table of Normal data area(non-PMT/BMTPOOL)
+	 * G - Good block; B - Bad block
+	 *			---------------------------
+	 * physical |G|G|B|G|B|B|G|G|G|G|B|G|B|
+	 *			---------------------------
+	 * What bb_tbl[i] looks like:
+	 *   physical block(i):
+	 *			 0 1 2 3 4 5 6 7 8 9 a b c
+	 *   mapped block(bb_tbl[i]):
+	 *			 0 1 3 6 7 8 9 b ......
+	 * ATTENTION:
+	 *		If new bad block ocurred(n), search bmt_tbl to find
+	 *		a available block(x), and fill in the bb_tbl[n] = x;
+	 */
+	for (i = 1; i < bmtd.pool_lba; i++) {
+		bbt->bb_tbl[i] = find_valid_block(bbt->bb_tbl[i - 1] + 1);
+		BBT_LOG("bb_tbl[0x%x] = 0x%x", i, bbt->bb_tbl[i]);
+		if (bbt->bb_tbl[i] == 0)
+			return -1;
+	}
+
+	/* Physical Block start Address of BMT pool */
+	bmtd.pool_pba = bbt->bb_tbl[i - 1] + 1;
+	if (bmtd.pool_pba >= bmtd.total_blks - 2) {
+		pr_info("nand: FATAL ERR: Too many bad blocks!!\n");
+		return -1;
+	}
+
+	BBT_LOG("pool_pba=0x%x", bmtd.pool_pba);
+	i = 0;
+	block = bmtd.pool_pba;
+	/*
+	 * The bmt table is used for runtime bad block mapping
+	 * G - Good block; B - Bad block
+	 *			---------------------------
+	 * physical |G|G|B|G|B|B|G|G|G|G|B|G|B|
+	 *			---------------------------
+	 *   block:	 0 1 2 3 4 5 6 7 8 9 a b c
+	 * What bmt_tbl[i] looks like in initial state:
+	 *   i:
+	 *			 0 1 2 3 4 5 6 7
+	 *   bmt_tbl[i].block:
+	 *			 0 1 3 6 7 8 9 b
+	 *   bmt_tbl[i].mapped:
+	 *			 N N N N N N N B
+	 *		N - Not mapped(Available)
+	 *		M - Mapped
+	 *		B - BMT
+	 * ATTENTION:
+	 *		BMT always in the last valid block in pool
+	 */
+	while ((block = find_valid_block(block)) != 0) {
+		bmt_tbl(bbt)[i].block = block;
+		bmt_tbl(bbt)[i].mapped = NO_MAPPED;
+		BBT_LOG("bmt_tbl[%d].block = 0x%x", i, block);
+		block++;
+		i++;
+	}
+
+	/* i - How many available blocks in pool, which is the length of bmt_tbl[]
+	 * bmtd.bmt_blk_idx - bmt_tbl[bmtd.bmt_blk_idx].block => the BMT block
+	 */
+	bmtd.bmt_blk_idx = i - 1;
+	bmt_tbl(bbt)[bmtd.bmt_blk_idx].mapped = BMT_MAPPED;
+
+	if (i < 1) {
+		pr_info("nand: FATAL ERR: no space to store BMT!!\n");
+		return -1;
+	}
+
+	pr_info("[BBT] %d available blocks in BMT pool\n", i);
+
+	return 0;
+}
+
+static bool is_valid_bmt(unsigned char *buf, unsigned char *fdm)
+{
+	struct bbbt *bbt = (struct bbbt *)buf;
+	u8 *sig = (u8*)bbt->signature + MAIN_SIGNATURE_OFFSET;
+
+
+	if (memcmp(bbt->signature + MAIN_SIGNATURE_OFFSET, "BMT", 3) == 0 &&
+		memcmp(fdm + OOB_SIGNATURE_OFFSET, "bmt", 3) == 0) {
+		if (bbt->version == BBMT_VERSION)
+			return true;
+	}
+	BBT_LOG("[BBT] BMT Version not match,upgrage preloader and uboot please! sig=%02x%02x%02x, fdm=%02x%02x%02x",
+		sig[0], sig[1], sig[2],
+		fdm[1], fdm[2], fdm[3]);
+	return false;
+}
+
+static u16 get_bmt_index(struct bbmt *bmt)
+{
+	int i = 0;
+
+	while (bmt[i].block != BMT_TBL_DEF_VAL) {
+		if (bmt[i].mapped == BMT_MAPPED)
+			return i;
+		i++;
+	}
+	return 0;
+}
+
+static struct bbbt *scan_bmt(u16 block)
+{
+	u8 fdm[4];
+
+	if (block < bmtd.pool_lba)
+		return NULL;
+
+	if (read_bmt(block, nand_bbt_buf, fdm, sizeof(fdm)))
+		return scan_bmt(block - 1);
+
+	if (is_valid_bmt(nand_bbt_buf, fdm)) {
+		bmtd.bmt_blk_idx = get_bmt_index(bmt_tbl((struct bbbt *)nand_bbt_buf));
+		if (bmtd.bmt_blk_idx == 0) {
+			pr_info("[BBT] FATAL ERR: bmt block index is wrong!\n");
+			return NULL;
+		}
+		pr_info("[BBT] BMT.v2 is found at 0x%x\n", block);
+		return (struct bbbt *)nand_bbt_buf;
+	} else
+		return scan_bmt(block - 1);
+}
+
+/* Write the Burner Bad Block Table to Nand Flash
+ * n - write BMT to bmt_tbl[n]
+ */
+static u16 upload_bmt(struct bbbt *bbt, int n)
+{
+	u16 block;
+
+retry:
+	if (n < 0 || bmt_tbl(bbt)[n].mapped == NORMAL_MAPPED) {
+		pr_info("nand: FATAL ERR: no space to store BMT!\n");
+		return (u16)-1;
+	}
+
+	block = bmt_tbl(bbt)[n].block;
+	BBT_LOG("n = 0x%x, block = 0x%x", n, block);
+	if (bbt_nand_erase(block)) {
+		bmt_tbl(bbt)[n].block = 0;
+		/* erase failed, try the previous block: bmt_tbl[n - 1].block */
+		n--;
+		goto retry;
+	}
+
+	/* The signature offset is fixed set to 0,
+	 * oob signature offset is fixed set to 1
+	 */
+	memcpy(bbt->signature + MAIN_SIGNATURE_OFFSET, "BMT", 3);
+	bbt->version = BBMT_VERSION;
+
+	if (write_bmt(block, (unsigned char *)bbt)) {
+		bmt_tbl(bbt)[n].block = 0;
+
+		/* write failed, try the previous block in bmt_tbl[n - 1] */
+		n--;
+		goto retry;
+	}
+
+	/* Return the current index(n) of BMT pool (bmt_tbl[n]) */
+	return n;
+}
+
+static u16 find_valid_block_in_pool(struct bbbt *bbt)
+{
+	int i;
+
+	if (bmtd.bmt_blk_idx == 0)
+		goto error;
+
+	for (i = 0; i < bmtd.bmt_blk_idx; i++) {
+		if (bmt_tbl(bbt)[i].block != 0 && bmt_tbl(bbt)[i].mapped == NO_MAPPED) {
+			bmt_tbl(bbt)[i].mapped = NORMAL_MAPPED;
+			return bmt_tbl(bbt)[i].block;
+		}
+	}
+
+error:
+	pr_info("nand: FATAL ERR: BMT pool is run out!\n");
+	return 0;
+}
+
+/* We met a bad block, mark it as bad and map it to a valid block in pool,
+ * if it's a write failure, we need to write the data to mapped block
+ */
+static bool update_bmt(u16 block)
+{
+	u16 mapped_blk;
+	struct bbbt *bbt;
+
+	bbt = bmtd.bbt;
+	mapped_blk = find_valid_block_in_pool(bbt);
+	if (mapped_blk == 0)
+		return false;
+
+	/* Map new bad block to available block in pool */
+	bbt->bb_tbl[block] = mapped_blk;
+	bmtd.bmt_blk_idx = upload_bmt(bbt, bmtd.bmt_blk_idx);
+
+	return true;
+}
+
+u16 get_mapping_block_index(int block)
+{
+	int mapping_block;
+
+	if (block < bmtd.pool_lba)
+		mapping_block = bmtd.bbt->bb_tbl[block];
+	else
+		mapping_block = block;
+	BBT_LOG("0x%x mapped to 0x%x", block, mapping_block);
+
+	return mapping_block;
+}
+
+static int
+mtk_bmt_read(struct mtd_info *mtd, loff_t from,
+	     struct mtd_oob_ops *ops)
+{
+	struct mtd_oob_ops cur_ops = *ops;
+	int retry_count = 0;
+	loff_t cur_from;
+	int ret;
+
+	ops->retlen = 0;
+	ops->oobretlen = 0;
+
+	while (ops->retlen < ops->len || ops->oobretlen < ops->ooblen) {
+		u32 offset = from & (bmtd.blk_size - 1);
+		u32 block = from >> bmtd.blk_shift;
+		u32 cur_block;
+
+		cur_block = get_mapping_block_index(block);
+		cur_from = ((loff_t)cur_block << bmtd.blk_shift) + offset;
+
+		cur_ops.oobretlen = 0;
+		cur_ops.retlen = 0;
+		cur_ops.len = min_t(u32, mtd->erasesize - offset,
+					 ops->len - ops->retlen);
+		ret = bmtd._read_oob(mtd, cur_from, &cur_ops);
+		if (ret < 0) {
+			update_bmt(block);
+			if (retry_count++ < 10)
+				continue;
+
+			return ret;
+		}
+
+		ops->retlen += cur_ops.retlen;
+		ops->oobretlen += cur_ops.oobretlen;
+
+		cur_ops.ooboffs = 0;
+		cur_ops.datbuf += cur_ops.retlen;
+		cur_ops.oobbuf += cur_ops.oobretlen;
+		cur_ops.ooblen -= cur_ops.oobretlen;
+
+		if (!cur_ops.len)
+			cur_ops.len = mtd->erasesize - offset;
+
+		from += cur_ops.len;
+		retry_count = 0;
+	}
+
+	return 0;
+}
+
+static int
+mtk_bmt_write(struct mtd_info *mtd, loff_t to,
+	      struct mtd_oob_ops *ops)
+{
+	struct mtd_oob_ops cur_ops = *ops;
+	int retry_count = 0;
+	loff_t cur_to;
+	int ret;
+
+	ops->retlen = 0;
+	ops->oobretlen = 0;
+
+	while (ops->retlen < ops->len || ops->oobretlen < ops->ooblen) {
+		u32 offset = to & (bmtd.blk_size - 1);
+		u32 block = to >> bmtd.blk_shift;
+		u32 cur_block;
+
+		cur_block = get_mapping_block_index(block);
+		cur_to = ((loff_t)cur_block << bmtd.blk_shift) + offset;
+
+		cur_ops.oobretlen = 0;
+		cur_ops.retlen = 0;
+		cur_ops.len = min_t(u32, bmtd.blk_size - offset,
+					 ops->len - ops->retlen);
+		ret = bmtd._write_oob(mtd, cur_to, &cur_ops);
+		if (ret < 0) {
+			update_bmt(block);
+			if (retry_count++ < 10)
+				continue;
+
+			return ret;
+		}
+
+		ops->retlen += cur_ops.retlen;
+		ops->oobretlen += cur_ops.oobretlen;
+
+		cur_ops.ooboffs = 0;
+		cur_ops.datbuf += cur_ops.retlen;
+		cur_ops.oobbuf += cur_ops.oobretlen;
+		cur_ops.ooblen -= cur_ops.oobretlen;
+
+		if (!cur_ops.len)
+			cur_ops.len = mtd->erasesize - offset;
+
+		to += cur_ops.len;
+		retry_count = 0;
+	}
+
+	return 0;
+}
+
+static int
+mtk_bmt_mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
+{
+	struct erase_info mapped_instr = {
+		.len = bmtd.blk_size,
+	};
+	int retry_count = 0;
+	u64 start_addr, end_addr;
+	int ret;
+	u16 orig_block, block;
+
+	start_addr = instr->addr & (~mtd->erasesize_mask);
+	end_addr = instr->addr + instr->len;
+
+	while (start_addr < end_addr) {
+		orig_block = start_addr >> bmtd.blk_shift;
+		block = get_mapping_block_index(orig_block);
+		mapped_instr.addr = (loff_t)block << bmtd.blk_shift;
+		ret = bmtd._erase(mtd, &mapped_instr);
+		if (ret) {
+			update_bmt(orig_block);
+			if (retry_count++ < 10)
+				continue;
+			instr->fail_addr = start_addr;
+			break;
+		}
+		start_addr += mtd->erasesize;
+		retry_count = 0;
+	}
+
+	return ret;
+}
+static int
+mtk_bmt_block_isbad(struct mtd_info *mtd, loff_t ofs)
+{
+	int retry_count = 0;
+	u16 orig_block = ofs >> bmtd.blk_shift;
+	u16 block;
+	int ret;
+
+retry:
+	block = get_mapping_block_index(orig_block);
+	ret = bmtd._block_isbad(mtd, (loff_t)block << bmtd.blk_shift);
+	if (ret) {
+		update_bmt(orig_block);
+		if (retry_count++ < 10)
+			goto retry;
+	}
+	return ret;
+}
+
+static int
+mtk_bmt_block_markbad(struct mtd_info *mtd, loff_t ofs)
+{
+	u16 orig_block = ofs >> bmtd.blk_shift;
+	u16 block = get_mapping_block_index(orig_block);
+	update_bmt(orig_block);
+	return bmtd._block_markbad(mtd, (loff_t)block << bmtd.blk_shift);
+}
+
+static void
+mtk_bmt_replace_ops(struct mtd_info *mtd)
+{
+	bmtd._read_oob = mtd->_read_oob;
+	bmtd._write_oob = mtd->_write_oob;
+	bmtd._erase = mtd->_erase;
+	bmtd._block_isbad = mtd->_block_isbad;
+	bmtd._block_markbad = mtd->_block_markbad;
+
+	mtd->_read_oob = mtk_bmt_read;
+	mtd->_write_oob = mtk_bmt_write;
+	mtd->_erase = mtk_bmt_mtd_erase;
+	mtd->_block_isbad = mtk_bmt_block_isbad;
+	mtd->_block_markbad = mtk_bmt_block_markbad;
+}
+
+static int mtk_bmt_debug_mark_good(void *data, u64 val)
+{
+	u32 block = val >> bmtd.blk_shift;
+
+	bmtd.bbt->bb_tbl[block] = block;
+	bmtd.bmt_blk_idx = upload_bmt(bmtd.bbt, bmtd.bmt_blk_idx);
+
+	return 0;
+}
+
+static int mtk_bmt_debug_mark_bad(void *data, u64 val)
+{
+	u32 block = val >> bmtd.blk_shift;
+
+	update_bmt(block);
+
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(fops_mark_good, NULL, mtk_bmt_debug_mark_good, "%llu\n");
+DEFINE_DEBUGFS_ATTRIBUTE(fops_mark_bad, NULL, mtk_bmt_debug_mark_bad, "%llu\n");
+
+static void
+mtk_bmt_add_debugfs(void)
+{
+	struct dentry *dir;
+
+	dir = bmtd.debugfs_dir = debugfs_create_dir("mtk-bmt", NULL);
+	if (!dir)
+		return;
+
+	debugfs_create_file_unsafe("mark_good", S_IWUSR, dir, NULL, &fops_mark_good);
+	debugfs_create_file_unsafe("mark_bad", S_IWUSR, dir, NULL, &fops_mark_bad);
+}
+
+void mtk_bmt_detach(struct mtd_info *mtd)
+{
+	if (bmtd.mtd != mtd)
+		return;
+
+	if (bmtd.debugfs_dir)
+		debugfs_remove_recursive(bmtd.debugfs_dir);
+	bmtd.debugfs_dir = NULL;
+
+	kfree(nand_bbt_buf);
+	kfree(nand_data_buf);
+
+	mtd->_read_oob = bmtd._read_oob;
+	mtd->_write_oob = bmtd._write_oob;
+	mtd->_erase = bmtd._erase;
+	mtd->_block_isbad = bmtd._block_isbad;
+	mtd->_block_markbad = bmtd._block_markbad;
+	mtd->size = bmtd.total_blks << bmtd.blk_shift;
+
+	memset(&bmtd, 0, sizeof(bmtd));
+}
+
+/* total_blocks - The total count of blocks that the Nand Chip has */
+int mtk_bmt_attach(struct mtd_info *mtd)
+{
+	struct device_node *np;
+	struct bbbt *bbt;
+	u32 bufsz;
+	u32 block;
+	u16 total_blocks, pmt_block;
+	int ret = 0;
+	u32 bmt_pool_size, bmt_table_size;
+
+	if (bmtd.mtd)
+		return -ENOSPC;
+
+	np = mtd_get_of_node(mtd);
+	if (!np)
+		return 0;
+
+	if (!of_property_read_bool(np, "mediatek,bmt-v2"))
+		return 0;
+
+	if (of_property_read_u32(np, "mediatek,bmt-pool-size",
+				 &bmt_pool_size) != 0)
+		bmt_pool_size = 80;
+
+	if (of_property_read_u8(np, "mediatek,bmt-oob-offset",
+				 &bmtd.oob_offset) != 0)
+		bmtd.oob_offset = 0;
+
+	if (of_property_read_u32(np, "mediatek,bmt-table-size",
+				 &bmt_table_size) != 0)
+		bmt_table_size = 0x2000U;
+
+	bmtd.mtd = mtd;
+	mtk_bmt_replace_ops(mtd);
+
+	bmtd.table_size = bmt_table_size;
+	bmtd.blk_size = mtd->erasesize;
+	bmtd.blk_shift = ffs(bmtd.blk_size) - 1;
+	bmtd.pg_size = mtd->writesize;
+	bmtd.pg_shift = ffs(bmtd.pg_size) - 1;
+	total_blocks = mtd->size >> bmtd.blk_shift;
+	pmt_block = total_blocks - bmt_pool_size - 2;
+
+	mtd->size = pmt_block << bmtd.blk_shift;
+
+	/*
+	 *  ---------------------------------------
+	 * | PMT(2blks) | BMT POOL(totalblks * 2%) |
+	 *  ---------------------------------------
+	 * ^            ^
+	 * |            |
+	 * pmt_block	pmt_block + 2blocks(pool_lba)
+	 *
+	 * ATTETION!!!!!!
+	 *     The blocks ahead of the boundary block are stored in bb_tbl
+	 *     and blocks behind are stored in bmt_tbl
+	 */
+
+	bmtd.pool_lba = (u16)(pmt_block + 2);
+	bmtd.total_blks = total_blocks;
+	bmtd.bb_max = bmtd.total_blks * BBPOOL_RATIO / 100;
+
+	/* 3 buffers we need */
+	bufsz = round_up(sizeof(struct bbbt) +
+			 bmt_table_size * sizeof(struct bbmt), bmtd.pg_size);
+	bmtd.bmt_pgs = bufsz >> bmtd.pg_shift;
+
+	nand_bbt_buf = kzalloc(bufsz, GFP_KERNEL);
+	nand_data_buf = kzalloc(bmtd.pg_size, GFP_KERNEL);
+
+	if (!nand_bbt_buf || !nand_data_buf) {
+		pr_info("nand: FATAL ERR: allocate buffer failed!\n");
+		ret = -1;
+		goto error;
+	}
+
+	memset(nand_bbt_buf, 0xff, bufsz);
+	memset(nand_data_buf, 0xff, bmtd.pg_size);
+
+	BBT_LOG("bbtbuf=0x%p(0x%x) dat=0x%p(0x%x)",
+			nand_bbt_buf, bufsz, nand_data_buf, bmtd.pg_size);
+	BBT_LOG("pool_lba=0x%x total_blks=0x%x bb_max=0x%x",
+			bmtd.pool_lba, bmtd.total_blks, bmtd.bb_max);
+
+	/* Scanning start from the first page of the last block
+	 * of whole flash
+	 */
+	bbt = scan_bmt(bmtd.total_blks - 1);
+	if (!bbt) {
+		/* BMT not found */
+		if (bmtd.total_blks > BB_TABLE_MAX + BMT_TABLE_MAX) {
+			pr_info("nand: FATAL: Too many blocks, can not support!\n");
+			ret = -1;
+			goto error;
+		}
+
+		bbt = (struct bbbt *)nand_bbt_buf;
+		memset(bmt_tbl(bbt), BMT_TBL_DEF_VAL, bmtd.table_size * sizeof(struct bbmt));
+
+		if (scan_bad_blocks(bbt)) {
+			ret = -1;
+			goto error;
+		}
+
+		/* BMT always in the last valid block in pool */
+		bmtd.bmt_blk_idx = upload_bmt(bbt, bmtd.bmt_blk_idx);
+		block = bmt_tbl(bbt)[bmtd.bmt_blk_idx].block;
+		pr_notice("[BBT] BMT.v2 is written into PBA:0x%x\n", block);
+
+		if (bmtd.bmt_blk_idx == 0)
+			pr_info("nand: Warning: no available block in BMT pool!\n");
+		else if (bmtd.bmt_blk_idx == (u16)-1) {
+			ret = -1;
+			goto error;
+		}
+	}
+	mtk_bmt_add_debugfs();
+
+	bmtd.bbt = bbt;
+	return 0;
+
+error:
+	mtk_bmt_detach(mtd);
+	return ret;
+}
+
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Xiangsheng Hou <xiangsheng.hou@mediatek.com>, Felix Fietkau <nbd@nbd.name>");
+MODULE_DESCRIPTION("Bad Block mapping management v2 for MediaTek NAND Flash Driver");
+
diff --git a/target/linux/generic/files/include/linux/mtd/mtk_bmt.h b/target/linux/generic/files/include/linux/mtd/mtk_bmt.h
new file mode 100644
index 0000000000..cbb6d04d89
--- /dev/null
+++ b/target/linux/generic/files/include/linux/mtd/mtk_bmt.h
@@ -0,0 +1,18 @@
+#ifndef __MTK_BMT_H
+#define __MTK_BMT_H
+
+#ifdef CONFIG_MTD_NAND_MTK_BMT
+int mtk_bmt_attach(struct mtd_info *mtd);
+void mtk_bmt_detach(struct mtd_info *mtd);
+#else
+static inline int mtk_bmt_attach(struct mtd_info *mtd)
+{
+	return 0;
+}
+
+static inline void mtk_bmt_detach(struct mtd_info *mtd)
+{
+}
+#endif
+
+#endif
diff --git a/target/linux/generic/hack-5.10/430-mtk-bmt-support.patch b/target/linux/generic/hack-5.10/430-mtk-bmt-support.patch
new file mode 100644
index 0000000000..749dcb8356
--- /dev/null
+++ b/target/linux/generic/hack-5.10/430-mtk-bmt-support.patch
@@ -0,0 +1,23 @@
+--- a/drivers/mtd/nand/Kconfig
++++ b/drivers/mtd/nand/Kconfig
+@@ -15,6 +15,10 @@ config MTD_NAND_ECC
+        bool
+        depends on MTD_NAND_CORE
+ 
++config MTD_NAND_MTK_BMT
++	bool "Support MediaTek NAND Bad-block Management Table"
++	default n
++
+ endmenu
+ 
+ endmenu
+--- a/drivers/mtd/nand/Makefile
++++ b/drivers/mtd/nand/Makefile
+@@ -2,6 +2,7 @@
+ 
+ nandcore-objs := core.o bbt.o
+ obj-$(CONFIG_MTD_NAND_CORE) += nandcore.o
++obj-$(CONFIG_MTD_NAND_MTK_BMT)	+= mtk_bmt.o
+ 
+ obj-y	+= onenand/
+ obj-y	+= raw/