mtd: bcm63xxpart: Extract read of image tag to separate function

Extract image tag reading and CRC check to a separate function.

Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

1 files changed, 40 insertions, 22 deletions

diff --git a/drivers/mtd/bcm63xxpart.c b/drivers/mtd/bcm63xxpart.c
index 1eea8b6bc66a..eafbf521a547 100644
--- a/drivers/mtd/bcm63xxpart.c
+++ b/drivers/mtd/bcm63xxpart.c
@@ -41,6 +41,10 @@
 #define BCM963XX_CFE_VERSION_OFFSET     0x570
 #define BCM963XX_NVRAM_OFFSET           0x580
 
+/* Ensure strings read from flash structs are null terminated */
+#define STR_NULL_TERMINATE(x) \
+        do { char *_str = (x); _str[sizeof(x) - 1] = 0; } while (0)
+
 static int bcm63xx_detect_cfe(struct mtd_info *master)
 {
         char buf[9];
@@ -89,6 +93,37 @@ static int bcm63xx_read_nvram(struct mtd_info *master,
         return 0;
 }
 
+static int bcm63xx_read_image_tag(struct mtd_info *master, const char *name,
+        loff_t tag_offset, struct bcm_tag *buf)
+{
+        int ret;
+        size_t retlen;
+        u32 computed_crc;
+
+        ret = mtd_read(master, tag_offset, sizeof(*buf), &retlen, (void *)buf);
+        if (ret)
+                return ret;
+
+        if (retlen != sizeof(*buf))
+                return -EIO;
+
+        computed_crc = crc32_le(IMAGETAG_CRC_START, (u8 *)buf,
+                                offsetof(struct bcm_tag, header_crc));
+        if (computed_crc == buf->header_crc) {
+                STR_NULL_TERMINATE(buf->board_id);
+                STR_NULL_TERMINATE(buf->tag_version);
+
+                pr_info("%s: CFE image tag found at 0x%llx with version %s, board type %s\n",
+                        name, tag_offset, buf->tag_version, buf->board_id);
+
+                return 0;
+        }
+
+        pr_warn("%s: CFE image tag at 0x%llx CRC invalid (expected %08x, actual %08x)\n",
+                name, tag_offset, buf->header_crc, computed_crc);
+        return 1;
+}
+
 static int bcm63xx_parse_cfe_partitions(struct mtd_info *master,
                                         const struct mtd_partition **pparts,
                                         struct mtd_part_parser_data *data)
@@ -99,13 +134,11 @@ static int bcm63xx_parse_cfe_partitions(struct mtd_info *master,
         struct bcm_tag *buf = NULL;
         struct mtd_partition *parts;
         int ret;
-        size_t retlen;
         unsigned int rootfsaddr, kerneladdr, spareaddr;
         unsigned int rootfslen, kernellen, sparelen, totallen;
         unsigned int cfelen, nvramlen;
         unsigned int cfe_erasesize;
         int i;
-        u32 computed_crc;
         bool rootfs_first = false;
 
         if (bcm63xx_detect_cfe(master))
@@ -134,28 +167,13 @@ static int bcm63xx_parse_cfe_partitions(struct mtd_info *master,
         }
 
         /* Get the tag */
-        ret = mtd_read(master, cfelen, sizeof(struct bcm_tag), &retlen,
-                       (void *)buf);
-
-        if (retlen != sizeof(struct bcm_tag)) {
-                ret = -EIO;
-                goto out;
-        }
-
-        computed_crc = crc32_le(IMAGETAG_CRC_START, (u8 *)buf,
-                                offsetof(struct bcm_tag, header_crc));
-        if (computed_crc == buf->header_crc) {
-                char *boardid = &(buf->board_id[0]);
-                char *tagversion = &(buf->tag_version[0]);
-
+        ret = bcm63xx_read_image_tag(master, "rootfs", cfelen, buf);
+        if (!ret) {
                 sscanf(buf->flash_image_start, "%u", &rootfsaddr);
                 sscanf(buf->kernel_address, "%u", &kerneladdr);
                 sscanf(buf->kernel_length, "%u", &kernellen);
                 sscanf(buf->total_length, "%u", &totallen);
 
-                pr_info("CFE boot tag found with version %s and board type %s\n",
-                        tagversion, boardid);
-
                 kerneladdr = kerneladdr - BCM963XX_EXTENDED_SIZE;
                 rootfsaddr = rootfsaddr - BCM963XX_EXTENDED_SIZE;
                 spareaddr = roundup(totallen, master->erasesize) + cfelen;
@@ -169,13 +187,13 @@ static int bcm63xx_parse_cfe_partitions(struct mtd_info *master,
                         rootfsaddr = kerneladdr + kernellen;
                         rootfslen = spareaddr - rootfsaddr;
                 }
-        } else {
-                pr_warn("CFE boot tag CRC invalid (expected %08x, actual %08x)\n",
-                        buf->header_crc, computed_crc);
+        } else if (ret > 0) {
                 kernellen = 0;
                 rootfslen = 0;
                 rootfsaddr = 0;
                 spareaddr = cfelen;
+        } else {
+                goto out;
         }
         sparelen = master->size - spareaddr - nvramlen;