[PATCH] MIPS: BCM63XX: fix nvram checksum calculation

[Jonas Gorski <jonas.gorski@gmail.com>]

The current checksum calculation code does nothing except checking that
the first byte of nvram is 0 without actually checking the checksum.

Implement the correct checksum calculation by calculating the crc32 with
the checksum field set to 0.

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
---

This patch depends on the previous nvram patch ("move nvram functions
into their own file").

 arch/mips/bcm63xx/nvram.c |   23 +++++++++++++----------
 1 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/arch/mips/bcm63xx/nvram.c b/arch/mips/bcm63xx/nvram.c
index b57a10d..6206116 100644
--- a/arch/mips/bcm63xx/nvram.c
+++ b/arch/mips/bcm63xx/nvram.c
@@ -11,6 +11,7 @@
 #define pr_fmt(fmt) "bcm63xx_nvram: " fmt
 
 #include <linux/init.h>
+#include <linux/crc32.h>
 #include <linux/export.h>
 #include <linux/kernel.h>
 #include <linux/if_ether.h>
@@ -40,23 +41,25 @@ static int mac_addr_used;
 int __init bcm63xx_nvram_init(void *addr)
 {
        unsigned int check_len;
-       u8 *p;
-       u32 val;
+       u32 crc, expected_crc;
 
        /* extract nvram data */
        memcpy(&nvram, addr, sizeof(nvram));
 
        /* check checksum before using data */
-       if (nvram.version <= 4)
-               check_len = offsetof(struct bcm963xx_nvram, checksum_old);
-       else
+       if (nvram.version <= 4) {
+               check_len = offsetof(struct bcm963xx_nvram, reserved3);
+               expected_crc = nvram.checksum_old;
+               nvram.checksum_old = 0;
+       } else {
                check_len = sizeof(nvram);
-       val = 0;
-       p = (u8 *)&nvram;
+               expected_crc = nvram.checksum_high;
+               nvram.checksum_high = 0;
+       }
+
+       crc = crc32_le(~0, (u8 *)&nvram, check_len);
 
-       while (check_len--)
-               val += *p;
-       if (val)
+       if (crc != expected_crc)
                return -EINVAL;
 
        return 0;
-- 
1.7.2.5