[PATCH v8 1/2] mtd: nand_bbt: Move BBT block selection logic out of write_bbt()

Kyle Roeschley
2016-08-15T23:21:34Z

From: Boris Brezillon <boris.brezillon@free-electrons.com>

This clarifies the write_bbt() by removing the write label and
clarifying the error/exit path.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: Kyle Roeschley <kyle.roeschley@ni.com>
---
v8: Move the chip indexing change back into patch 2

v7: Move all code cleanup into first patch
Correct documentation of mark_bbt_block_bad
Make pr_warn messages consistent
Add Tested-bys

v6: Split functionality of write_bbt out into new functions

v5: De-duplicate bad block handling

v4: Don't ignore write protection while marking bad BBT blocks
Correctly call block_markbad
Minor cleanups

v3: Don't overload mtd->priv
Keep nand_erase_nand from erroring on protected BBT blocks

v2: Mark OOB area in each block as well as BBT
Avoid marking read-only, bad address, or known bad blocks as bad

drivers/mtd/nand/nand_bbt.c | 110 +++++++++++++++++++++++++++++---------------
1 file changed, 74 insertions(+), 36 deletions(-)

diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
index 2fbb523..9fbd664 100644
--- a/drivers/mtd/nand/nand_bbt.c
+++ b/drivers/mtd/nand/nand_bbt.c
@@ -605,6 +605,69 @@ static void search_read_bbts(struct mtd_info *mtd, uint8_t *buf,
}

/**
+ * get_bbt_block - Get the first valid eraseblock suitable to store a BBT
+ * @this: the NAND device
+ * @td: the BBT description
+ * @md: the mirror BBT descriptor
+ * @chip: the CHIP selector
+ *
+ * This functions returns a positive block number pointing a valid eraseblock
+ * suitable to store a BBT (i.e. in the range reserved for BBT), or -ENOSPC if
+ * all blocks are already used of marked bad. If td->pages[chip] was already
+ * pointing to a valid block we re-use it, otherwise we search for the next
+ * valid one.
+ */
+static int get_bbt_block(struct nand_chip *this, struct nand_bbt_descr *td,
+ struct nand_bbt_descr *md, int chip)
+{
+ int startblock, dir, page, numblocks, i;
+
+ /*
+ * There was already a version of the table, reuse the page. This
+ * applies for absolute placement too, as we have the page number in
+ * td->pages.
+ */
+ if (td->pages[chip] != -1)
+ return td->pages[chip] >>
+ (this->bbt_erase_shift - this->page_shift);
+
+ numblocks = (int)(this->chipsize >> this->bbt_erase_shift);
+ if (!(td->options & NAND_BBT_PERCHIP))
+ numblocks *= this->numchips;
+
+ /*
+ * Automatic placement of the bad block table. Search direction
+ * top -> down?
+ */
+ if (td->options & NAND_BBT_LASTBLOCK) {
+ startblock = numblocks * (chip + 1) - 1;
+ dir = -1;
+ } else {
+ startblock = chip * numblocks;
+ dir = 1;
+ }
+
+ for (i = 0; i < td->maxblocks; i++) {
+ int block = startblock + dir * i;
+
+ /* Check, if the block is bad */
+ switch (bbt_get_entry(this, block)) {
+ case BBT_BLOCK_WORN:
+ case BBT_BLOCK_FACTORY_BAD:
+ continue;
+ }
+
+ page = block << (this->bbt_erase_shift - this->page_shift);
+
+ /* Check, if the block is used by the mirror table */
+ if (!md || md->pages[chip] != page)
+ return block;
+ }
+
+ return -ENOSPC;
+}
+
+/**
* write_bbt - [GENERIC] (Re)write the bad block table
* @mtd: MTD device structure
* @buf: temporary buffer
@@ -621,7 +684,7 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
struct nand_chip *this = mtd_to_nand(mtd);
struct erase_info einfo;
int i, res, chip = 0;
- int bits, startblock, dir, page, offs, numblocks, sft, sftmsk;
+ int bits, page, offs, numblocks, sft, sftmsk;
int nrchips, pageoffs, ooboffs;
uint8_t msk[4];
uint8_t rcode = td->reserved_block_code;
@@ -653,45 +716,20 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,

/* Loop through the chips */
for (; chip < nrchips; chip++) {
- /*
- * There was already a version of the table, reuse the page
- * This applies for absolute placement too, as we have the
- * page nr. in td->pages.
- */
- if (td->pages[chip] != -1) {
- page = td->pages[chip];
- goto write;
+ int block;
+
+ block = get_bbt_block(this, td, md, chip);
+ if (block < 0) {
+ pr_err("No space left to write bad block table\n");
+ res = block;
+ goto outerr;
}

/*
- * Automatic placement of the bad block table. Search direction
- * top -> down?
+ * get_bbt_block() returns a block number, shift the value to
+ * get a page number.
*/
- if (td->options & NAND_BBT_LASTBLOCK) {
- startblock = numblocks * (chip + 1) - 1;
- dir = -1;
- } else {
- startblock = chip * numblocks;
- dir = 1;
- }
-
- for (i = 0; i < td->maxblocks; i++) {
- int block = startblock + dir * i;
- /* Check, if the block is bad */
- switch (bbt_get_entry(this, block)) {
- case BBT_BLOCK_WORN:
- case BBT_BLOCK_FACTORY_BAD:
- continue;
- }
- page = block <<
- (this->bbt_erase_shift - this->page_shift);
- /* Check, if the block is used by the mirror table */
- if (!md || md->pages[chip] != page)
- goto write;
- }
- pr_err("No space left to write bad block table\n");
- return -ENOSPC;
- write:
+ page = block << (this->bbt_erase_shift - this->page_shift);

/* Set up shift count and masks for the flash table */
bits = td->options & NAND_BBT_NRBITS_MSK;
--
2.8.1