mtd: bcm47xxpart: look for NVRAM at the end of device

NVRAM is always placed at the end of device and it does not have to
start at the beginning of a block, so check few possible offsets.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 25 insertions, 7 deletions

diff --git a/drivers/mtd/bcm47xxpart.c b/drivers/mtd/bcm47xxpart.c
index 4552afbad4d0..9279a9174f84 100644
--- a/drivers/mtd/bcm47xxpart.c
+++ b/drivers/mtd/bcm47xxpart.c
@@ -63,6 +63,7 @@ static int bcm47xxpart_parse(struct mtd_info *master,
         struct trx_header *trx;
         int trx_part = -1;
         int last_trx_part = -1;
+        int possible_nvram_sizes[] = { 0x8000, 0xF000, 0x10000, };
 
         if (blocksize <= 0x10000)
                 blocksize = 0x10000;
@@ -99,13 +100,6 @@ static int bcm47xxpart_parse(struct mtd_info *master,
                         continue;
                 }
 
-                /* Standard NVRAM */
-                if (buf[0x000 / 4] == NVRAM_HEADER) {
-                        bcm47xxpart_add_part(&parts[curr_part++], "nvram",
-                                             offset, 0);
-                        continue;
-                }
-
                 /*
                  * board_data starts with board_id which differs across boards,
                  * but we can use 'MPFR' (hopefully) magic at 0x100
@@ -174,6 +168,30 @@ static int bcm47xxpart_parse(struct mtd_info *master,
                         continue;
                 }
         }
+
+        /* Look for NVRAM at the end of the last block. */
+        for (i = 0; i < ARRAY_SIZE(possible_nvram_sizes); i++) {
+                if (curr_part > BCM47XXPART_MAX_PARTS) {
+                        pr_warn("Reached maximum number of partitions, scanning stopped!\n");
+                        break;
+                }
+
+                offset = master->size - possible_nvram_sizes[i];
+                if (mtd_read(master, offset, 0x4, &bytes_read,
+                             (uint8_t *)buf) < 0) {
+                        pr_err("mtd_read error while reading at offset 0x%X!\n",
+                               offset);
+                        continue;
+                }
+
+                /* Standard NVRAM */
+                if (buf[0] == NVRAM_HEADER) {
+                        bcm47xxpart_add_part(&parts[curr_part++], "nvram",
+                                             master->size - blocksize, 0);
+                        break;
+                }
+        }
+
         kfree(buf);
 
         /*