dfu, nand: before write a buffer to nand, erase the nand sectors

before writing the received buffer to nand, erase the nand
sectors. If not doing this, nand write fails. See for
more info here:

http://lists.denx.de/pipermail/u-boot/2013-June/156361.html

Using the nand erase option "spread", maybe overwrite
blocks on, for example another mtd partition, if the
erasing range contains bad blocks.
So a limit option is added to nand_erase_opts()

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Tom Rini <trini@ti.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>

drivers/dfu/dfu_nand.c

@@ -63,12 +63,26 @@ static int nand_block_op(enum dfu_nand_op op, struct dfu_entity *dfu,
 
 	nand = &nand_info[nand_curr_device];
 
-	if (op == DFU_OP_READ)
+	if (op == DFU_OP_READ) {
 		ret = nand_read_skip_bad(nand, start, &count, &actual,
 				lim, buf);
-	else
+	} else {
+		nand_erase_options_t opts;
+
+		memset(&opts, 0, sizeof(opts));
+		opts.offset = start;
+		opts.length = count;
+		opts.spread = 1;
+		opts.quiet = 1;
+		opts.lim = lim;
+		/* first erase */
+		ret = nand_erase_opts(nand, &opts);
+		if (ret)
+			return ret;
+		/* then write */
 		ret = nand_write_skip_bad(nand, start, &count, &actual,
 				lim, buf, 0);
+	}
 
 	if (ret != 0) {
 		printf("%s: nand_%s_skip_bad call failed at %llx!\n",

drivers/mtd/nand/nand_util.c

@@ -120,6 +120,10 @@ int nand_erase_opts(nand_info_t *meminfo, const nand_erase_options_t *opts)
 
 		WATCHDOG_RESET();
 
+		if (opts->lim && (erase.addr >= (opts->offset + opts->lim))) {
+			puts("Size of erase exceeds limit\n");
+			return -EFBIG;
+		}
 		if (!opts->scrub && bbtest) {
 			int ret = mtd_block_isbad(meminfo, erase.addr);
 			if (ret > 0) {

include/nand.h

@@ -125,6 +125,8 @@ struct nand_erase_options {
 
 	/* Don't include skipped bad blocks in size to be erased */
 	int spread;
+	/* maximum size that actual may be in order to not exceed the buf */
+	loff_t lim;
 };
 
 typedef struct nand_erase_options nand_erase_options_t;