UBI: introduce flash dump helper

Useful for debugging problems, compiled in only if UBI debugging
is enabled. This patch also makes the UBI writing function dump
the flash if it fails to write.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/debug.c b/drivers/mtd/ubi/debug.c
index 54b0186915fb..4876977e52cb 100644
--- a/drivers/mtd/ubi/debug.c
+++ b/drivers/mtd/ubi/debug.c
@@ -196,4 +196,36 @@ void ubi_dbg_dump_mkvol_req(const struct ubi_mkvol_req *req)
 	printk(KERN_DEBUG "\t1st 16 characters of name: %s\n", nm);
 }
 
+/**
+ * ubi_dbg_dump_flash - dump a region of flash.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to dump
+ * @offset: the starting offset within the physical eraseblock to dump
+ * @len: the length of the region to dump
+ */
+void ubi_dbg_dump_flash(struct ubi_device *ubi, int pnum, int offset, int len)
+{
+	int err;
+	size_t read;
+	void *buf;
+	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
+
+	buf = vmalloc(len);
+	if (!buf)
+		return;
+	err = ubi->mtd->read(ubi->mtd, addr, len, &read, buf);
+	if (err && err != -EUCLEAN) {
+		ubi_err("error %d while reading %d bytes from PEB %d:%d, "
+			"read %zd bytes", err, len, pnum, offset, read);
+		goto out;
+	}
+
+	dbg_msg("dumping %d bytes of data from PEB %d, offset %d",
+		len, pnum, offset);
+	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1, buf, len, 1);
+out:
+	vfree(buf);
+	return;
+}
+
 #endif /* CONFIG_MTD_UBI_DEBUG */