[PATCH 2/6] mtd: afs: simplify partition detection

Linus Walleij
2019-01-28T13:55:35Z

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>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
drivers/mtd/parsers/afs.c | 33 ++++++++++++++++++++++-----------
1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/drivers/mtd/parsers/afs.c b/drivers/mtd/parsers/afs.c
index c489938cd665..ccc198818057 100644
--- 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;