mtd: bcm47xxpart: move TRX parsing code to separated function

This change simplifies main parsing loop logic a bit. In future it may
be useful for moving TRX support to separated module / parser (if we
implement support for them at some point).
Finally parsing TRX at the end puts us in a better position as we have
better flash layout knowledge. It may be useful e.g. if it appears there
is more than 1 TRX partition.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/bcm47xxpart.c

@@ -83,6 +83,67 @@ static const char *bcm47xxpart_trx_data_part_name(struct mtd_info *master,
 	return "rootfs";
 }
 
+static int bcm47xxpart_parse_trx(struct mtd_info *master,
+				 struct mtd_partition *trx,
+				 struct mtd_partition *parts,
+				 size_t parts_len)
+{
+	struct trx_header header;
+	size_t bytes_read;
+	int curr_part = 0;
+	int i, err;
+
+	if (parts_len < 3) {
+		pr_warn("No enough space to add TRX partitions!\n");
+		return -ENOMEM;
+	}
+
+	err = mtd_read(master, trx->offset, sizeof(header), &bytes_read,
+		       (uint8_t *)&header);
+	if (err && !mtd_is_bitflip(err)) {
+		pr_err("mtd_read error while reading TRX header: %d\n", err);
+		return err;
+	}
+
+	i = 0;
+
+	/* We have LZMA loader if offset[2] points to sth */
+	if (header.offset[2]) {
+		bcm47xxpart_add_part(&parts[curr_part++], "loader",
+				     trx->offset + header.offset[i], 0);
+		i++;
+	}
+
+	if (header.offset[i]) {
+		bcm47xxpart_add_part(&parts[curr_part++], "linux",
+				     trx->offset + header.offset[i], 0);
+		i++;
+	}
+
+	if (header.offset[i]) {
+		size_t offset = trx->offset + header.offset[i];
+		const char *name = bcm47xxpart_trx_data_part_name(master,
+								  offset);
+
+		bcm47xxpart_add_part(&parts[curr_part++], name, offset, 0);
+		i++;
+	}
+
+	/*
+	 * Assume that every partition ends at the beginning of the one it is
+	 * followed by.
+	 */
+	for (i = 0; i < curr_part; i++) {
+		u64 next_part_offset = (i < curr_part - 1) ?
+					parts[i + 1].offset :
+					trx->offset + trx->size;
+
+		parts[i].size = next_part_offset - parts[i].offset;
+	}
+
+	return curr_part;
+}
+
 static int bcm47xxpart_parse(struct mtd_info *master,
 			     const struct mtd_partition **pparts,
 			     struct mtd_part_parser_data *data)
@@ -93,9 +154,7 @@ static int bcm47xxpart_parse(struct mtd_info *master,
 	size_t bytes_read;
 	uint32_t offset;
 	uint32_t blocksize = master->erasesize;
-	struct trx_header *trx;
 	int trx_part = -1;
-	int last_trx_part = -1;
 	int possible_nvram_sizes[] = { 0x8000, 0xF000, 0x10000, };
 	int err;
 
@@ -182,54 +241,14 @@ static int bcm47xxpart_parse(struct mtd_info *master,
 
 		/* TRX */
 		if (buf[0x000 / 4] == TRX_MAGIC) {
-			if (BCM47XXPART_MAX_PARTS - curr_part < 4) {
-				pr_warn("Not enough partitions left to register trx, scanning stopped!\n");
-				break;
-			}
-
-			trx = (struct trx_header *)buf;
+			struct trx_header *trx;
 
 			trx_part = curr_part;
 			bcm47xxpart_add_part(&parts[curr_part++], "firmware",
 					     offset, 0);
 
-			i = 0;
-			/* We have LZMA loader if offset[2] points to sth */
-			if (trx->offset[2]) {
-				bcm47xxpart_add_part(&parts[curr_part++],
-						     "loader",
-						     offset + trx->offset[i],
-						     0);
-				i++;
-			}
-
-			if (trx->offset[i]) {
-				bcm47xxpart_add_part(&parts[curr_part++],
-						     "linux",
-						     offset + trx->offset[i],
-						     0);
-				i++;
-			}
-
-			/*
-			 * Pure rootfs size is known and can be calculated as:
-			 * trx->length - trx->offset[i]. We don't fill it as
-			 * we want to have jffs2 (overlay) in the same mtd.
-			 */
-			if (trx->offset[i]) {
-				const char *name;
-
-				name = bcm47xxpart_trx_data_part_name(master, offset + trx->offset[i]);
-				bcm47xxpart_add_part(&parts[curr_part++],
-						     name,
-						     offset + trx->offset[i],
-						     0);
-				i++;
-			}
-
-			last_trx_part = curr_part - 1;
-
 			/* Jump to the end of TRX */
+			trx = (struct trx_header *)buf;
 			offset = roundup(offset + trx->length, blocksize);
 			/* Next loop iteration will increase the offset */
 			offset -= blocksize;
@@ -307,9 +326,17 @@ static int bcm47xxpart_parse(struct mtd_info *master,
 				       parts[i + 1].offset : master->size;
 
 		parts[i].size = next_part_offset - parts[i].offset;
-		if (i == last_trx_part && trx_part >= 0)
-			parts[trx_part].size = next_part_offset -
-					       parts[trx_part].offset;
+	}
+
+	/* If there was TRX parse it now */
+	if (trx_part >= 0) {
+		int num_parts;
+
+		num_parts = bcm47xxpart_parse_trx(master, &parts[trx_part],
+						  parts + curr_part,
+						  BCM47XXPART_MAX_PARTS - curr_part);
+		if (num_parts > 0)
+			curr_part += num_parts;
 	}
 
 	*pparts = parts;