mtd: clean-up the default_mtd_writev function

1. Teach 'mtd_write()' function to return '-EROFS' if the write method
   is undefined, and remove the corresponding check from
   'default_mtd_writev()'.
2. Do not test 'retlen' for NULL - it cannot be NULL.
3. Few minor coding stile clean-ups.
4. Add a kerneldoc comment

Additionally, minor fixes to the kerneldoc comments of the neighbor function.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 671c89289fc3..f0dd5a305b89 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -291,6 +291,8 @@ static inline int mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
                             size_t *retlen, const u_char *buf)
 {
         *retlen = 0;
+        if (!mtd->write)
+                return -EROFS;
         return mtd->write(mtd, to, len, retlen, buf);
 }