mtd: afs: simplify partition detection

Instead of reading out the AFS footers twice, create a separate
function to just check if there is a footer or not. Rids a few
local variables and prepare us to join the actual parser into
one function.

Cc: Ryan Harkin <ryan.harkin@linaro.org>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Richard Weinberger <richard@nod.at>

diff --git a/drivers/mtd/parsers/afs.c b/drivers/mtd/parsers/afs.c
index c489938..ccc1988 100644 (file)
--- a/drivers/mtd/parsers/afs.c
+++ b/drivers/mtd/parsers/afs.c
@@ -68,6 +68,26 @@ static u32 word_sum(void *words, int num)
        return sum;
 }
 
+static bool afs_is_v1(struct mtd_info *mtd, u_int off)
+{
+       /* The magic is 12 bytes from the end of the erase block */
+       u_int ptr = off + mtd->erasesize - 12;
+       u32 magic;
+       size_t sz;
+       int ret;
+
+       ret = mtd_read(mtd, ptr, 4, &sz, (u_char *)&magic);
+       if (ret < 0) {
+               printk(KERN_ERR "AFS: mtd read failed at 0x%x: %d\n",
+                      ptr, ret);
+               return false;
+       }
+       if (ret >= 0 && sz != 4)
+               return false;
+
+       return (magic == AFSV1_FOOTER_MAGIC);
+}
+
 static int
 afs_read_footer_v1(struct mtd_info *mtd, u_int *img_start, u_int *iis_start,
                   u_int off, u_int mask)
@@ -176,18 +196,9 @@ static int parse_afs_partitions(struct mtd_info *mtd,
         */
        mask = mtd->size - 1;
 
-       /*
-        * First, calculate the size of the array we need for the
-        * partition information.  We include in this the size of
-        * the strings.
-        */
+       /* Count the partitions by looping over all erase blocks */
        for (i = off = sz = 0; off < mtd->size; off += mtd->erasesize) {
-               u_int iis_ptr, img_ptr;
-
-               ret = afs_read_footer_v1(mtd, &img_ptr, &iis_ptr, off, mask);
-               if (ret < 0)
-                       return ret;
-               if (ret) {
+               if (afs_is_v1(mtd, off)) {
                        sz += sizeof(struct mtd_partition);
                        i += 1;
                }