[PATCH V2 2/4] mtd: nand: mxs_nand_spl: Fix bad block skipping

[Michael Trimarchi]

The specific implementation was having bug. Those bugs are since
the beginning of the implementation. Some manufactures can receive
this bug in their SPL code. This bug start to be more visible on
architecture that has complicated boot process like imx8mn. Older
version of uboot has the same problem only if the bad block
appear in correspoding of befine of u-boot image. In order to
adjust the function we scan from the first block. The logic
is not changed to have a simple way to fix without get regression.

The problematic part of old code was in this part:

while (is_badblock(mtd, offs, 1)) {
           page = page + nand_page_per_block;
          /* Check i we've reached the end of flash. */
          if (page >= mtd->size >> chip->page_shift) {
                      free(page_buf);
                      return -ENOMEM;
         }
}

Even we fix it adding increment of the offset of one erase block size
we don't fix the problem, because the first erase block where the
image start is not checked. The code was tested on an imx8mn where
the boot rom api was not able to skip it. Apart of that other
architecure are using this code and all boards that has nand as boot
device can be affected

Cc: Han Xu <han.xu at nxp.com>
Cc: Fabio Estevam <festevam at gmail.com>
Signed-off-by: Michael Trimarchi <michael at amarulasolutions.com>
---
V1->V2:
	- Adjust the commit message
	- Add Cc Han Xu and Fabio
	- fix size >= 0 to > 0
---
 drivers/mtd/nand/raw/mxs_nand_spl.c | 90 ++++++++++++++++-------------
 1 file changed, 49 insertions(+), 41 deletions(-)

diff --git a/drivers/mtd/nand/raw/mxs_nand_spl.c b/drivers/mtd/nand/raw/mxs_nand_spl.c
index 59a67ee414..2bfb181007 100644
--- a/drivers/mtd/nand/raw/mxs_nand_spl.c
+++ b/drivers/mtd/nand/raw/mxs_nand_spl.c
@@ -218,14 +218,14 @@ void nand_init(void)
 	mxs_nand_setup_ecc(mtd);
 }
 
-int nand_spl_load_image(uint32_t offs, unsigned int size, void *buf)
+int nand_spl_load_image(uint32_t offs, unsigned int size, void *dst)
 {
-	struct nand_chip *chip;
-	unsigned int page;
+	unsigned int sz;
+	unsigned int block, lastblock;
+	unsigned int page, page_offset;
 	unsigned int nand_page_per_block;
-	unsigned int sz = 0;
+	struct nand_chip *chip;
 	u8 *page_buf = NULL;
-	u32 page_off;
 
 	chip = mtd_to_nand(mtd);
 	if (!chip->numchips)
@@ -235,47 +235,42 @@ int nand_spl_load_image(uint32_t offs, unsigned int size, void *buf)
 	if (!page_buf)
 		return -ENOMEM;
 
-	page = offs >> chip->page_shift;
-	page_off = offs & (mtd->writesize - 1);
+	/* offs has to be aligned to a page address! */
+	block = offs / mtd->erasesize;
+	lastblock = (offs + size - 1) / mtd->erasesize;
+	page = (offs % mtd->erasesize) / mtd->writesize;
+	page_offset = offs % mtd->writesize;
 	nand_page_per_block = mtd->erasesize / mtd->writesize;
 
-	debug("%s offset:0x%08x len:%d page:%x\n", __func__, offs, size, page);
-
-	while (size) {
-		if (mxs_read_page_ecc(mtd, page_buf, page) < 0)
-			return -1;
-
-		if (size > (mtd->writesize - page_off))
-			sz = (mtd->writesize - page_off);
-		else
-			sz = size;
-
-		memcpy(buf, page_buf + page_off, sz);
-
-		offs += mtd->writesize;
-		page++;
-		buf += (mtd->writesize - page_off);
-		page_off = 0;
-		size -= sz;
-
-		/*
-		 * Check if we have crossed a block boundary, and if so
-		 * check for bad block.
-		 */
-		if (!(page % nand_page_per_block)) {
-			/*
-			 * Yes, new block. See if this block is good. If not,
-			 * loop until we find a good block.
-			 */
-			while (is_badblock(mtd, offs, 1)) {
-				page = page + nand_page_per_block;
-				/* Check i we've reached the end of flash. */
-				if (page >= mtd->size >> chip->page_shift) {
+	while (block <= lastblock && size > 0) {
+		if (!is_badblock(mtd, mtd->erasesize * block, 1)) {
+			/* Skip bad blocks */
+			while (page < nand_page_per_block) {
+				int curr_page = nand_page_per_block * block + page;
+
+				if (mxs_read_page_ecc(mtd, page_buf, curr_page) < 0) {
 					free(page_buf);
-					return -ENOMEM;
+					return -EIO;
 				}
+
+				if (size > (mtd->writesize - page_offset))
+					sz = (mtd->writesize - page_offset);
+				else
+					sz = size;
+
+				memcpy(dst, page_buf + page_offset, sz);
+				dst += sz;
+				size -= sz;
+				page_offset = 0;
+				page++;
 			}
+
+			page = 0;
+		} else {
+			lastblock++;
 		}
+
+		block++;
 	}
 
 	free(page_buf);
@@ -294,6 +289,19 @@ void nand_deselect(void)
 
 u32 nand_spl_adjust_offset(u32 sector, u32 offs)
 {
-	/* Handle the offset adjust in nand_spl_load_image,*/
+	unsigned int block, lastblock;
+
+	block = sector / mtd->erasesize;
+	lastblock = (sector + offs) / mtd->erasesize;
+
+	while (block <= lastblock) {
+		if (is_badblock(mtd, block * mtd->erasesize, 1)) {
+			offs += mtd->erasesize;
+			lastblock++;
+		}
+
+		block++;
+	}
+
 	return offs;
 }
-- 
2.25.1