Revert "mtd: bcm47xxpart: improve probing of nvram partition"

This reverts commit be3781b71ac03723b552dc156931620634ef1b22.

Some CFE bootloaders have NVRAM at offset 0x1000. With that patch we
were detecting such a bootloaders as a standard NVRAM partition.
Changing anything in this pseudo-NVRAM resulted in corrupted bootloader
and bricked device!

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

1 files changed, 9 insertions, 13 deletions

diff --git a/drivers/mtd/bcm47xxpart.c b/drivers/mtd/bcm47xxpart.c
index 63feb75cc8e0..4552afbad4d0 100644
--- a/drivers/mtd/bcm47xxpart.c
+++ b/drivers/mtd/bcm47xxpart.c
@@ -19,6 +19,12 @@
 /* 10 parts were found on sflash on Netgear WNDR4500 */
 #define BCM47XXPART_MAX_PARTS           12
 
+/*
+ * Amount of bytes we read when analyzing each block of flash memory.
+ * Set it big enough to allow detecting partition and reading important data.
+ */
+#define BCM47XXPART_BYTES_TO_READ       0x404
+
 /* Magics */
 #define BOARD_DATA_MAGIC                0x5246504D      /* MPFR */
 #define POT_MAGIC1                      0x54544f50      /* POTT */
@@ -57,17 +63,14 @@ static int bcm47xxpart_parse(struct mtd_info *master,
         struct trx_header *trx;
         int trx_part = -1;
         int last_trx_part = -1;
-        int max_bytes_to_read = 0x8004;
 
         if (blocksize <= 0x10000)
                 blocksize = 0x10000;
-        if (blocksize == 0x20000)
-                max_bytes_to_read = 0x18004;
 
         /* Alloc */
         parts = kzalloc(sizeof(struct mtd_partition) * BCM47XXPART_MAX_PARTS,
                         GFP_KERNEL);
-        buf = kzalloc(max_bytes_to_read, GFP_KERNEL);
+        buf = kzalloc(BCM47XXPART_BYTES_TO_READ, GFP_KERNEL);
 
         /* Parse block by block looking for magics */
         for (offset = 0; offset <= master->size - blocksize;
@@ -82,7 +85,7 @@ static int bcm47xxpart_parse(struct mtd_info *master,
                 }
 
                 /* Read beginning of the block */
-                if (mtd_read(master, offset, max_bytes_to_read,
+                if (mtd_read(master, offset, BCM47XXPART_BYTES_TO_READ,
                              &bytes_read, (uint8_t *)buf) < 0) {
                         pr_err("mtd_read error while parsing (offset: 0x%X)!\n",
                                offset);
@@ -97,16 +100,9 @@ static int bcm47xxpart_parse(struct mtd_info *master,
                 }
 
                 /* Standard NVRAM */
-                if (buf[0x000 / 4] == NVRAM_HEADER ||
-                    buf[0x1000 / 4] == NVRAM_HEADER ||
-                    buf[0x8000 / 4] == NVRAM_HEADER ||
-                    (blocksize == 0x20000 && (
-                      buf[0x10000 / 4] == NVRAM_HEADER ||
-                      buf[0x11000 / 4] == NVRAM_HEADER ||
-                      buf[0x18000 / 4] == NVRAM_HEADER))) {
+                if (buf[0x000 / 4] == NVRAM_HEADER) {
                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
                                              offset, 0);
-                        offset = rounddown(offset, blocksize);
                         continue;
                 }