mtd: bcm47xxpart: find NVRAM partitions in middle blocks

Old devices used to have NVRAM at the very end of flash and they could
be unaligned (starting at some offset in a block).
In new devices NVRAM can be located quite randomly, however it seems to
always start at the beginning of a block. For example Netgear R6250 has
NVRAM located right after the bootloader, before the kernel partition.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/mtd/bcm47xxpart.c b/drivers/mtd/bcm47xxpart.c
index adfa74c1bc45..8057f52a45b7 100644
--- a/drivers/mtd/bcm47xxpart.c
+++ b/drivers/mtd/bcm47xxpart.c
@@ -199,6 +199,17 @@ static int bcm47xxpart_parse(struct mtd_info *master,
                         continue;
                 }
 
+                /*
+                 * New (ARM?) devices may have NVRAM in some middle block. Last
+                 * block will be checked later, so skip it.
+                 */
+                if (offset != master->size - blocksize &&
+                    buf[0x000 / 4] == NVRAM_HEADER) {
+                        bcm47xxpart_add_part(&parts[curr_part++], "nvram",
+                                             offset, 0);
+                        continue;
+                }
+
                 /* Read middle of the block */
                 if (mtd_read(master, offset + 0x8000, 0x4,
                              &bytes_read, (uint8_t *)buf) < 0) {