s390/cio: Use generalized CCW handler in cp_init()

It is now pretty apparent that ccwchain_handle_ccw()
(nee ccwchain_handle_tic()) does everything that cp_init()
wants to do.

Let's remove that duplicated code from cp_init() and let
ccwchain_handle_ccw() handle it itself.
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20190606202831.44135-5-farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

drivers/s390/cio/vfio_ccw_cp.c

@@ -744,9 +744,7 @@ static int ccwchain_fetch_one(struct ccwchain *chain,
  */
 int cp_init(struct channel_program *cp, struct device *mdev, union orb *orb)
 {
-	u64 iova = orb->cmd.cpa;
-	struct ccwchain *chain;
-	int len, ret;
+	int ret;
 
 	/*
 	 * XXX:
@@ -759,28 +757,11 @@ int cp_init(struct channel_program *cp, struct device *mdev, union orb *orb)
 	memcpy(&cp->orb, orb, sizeof(*orb));
 	cp->mdev = mdev;
 
-	/* Get chain length. */
-	len = ccwchain_calc_length(iova, cp);
-	if (len < 0)
-		return len;
-
-	/* Alloc mem for the head chain. */
-	chain = ccwchain_alloc(cp, len);
-	if (!chain)
-		return -ENOMEM;
-	chain->ch_iova = iova;
-
-	/* Copy the head chain from guest. */
-	ret = copy_ccw_from_iova(cp, chain->ch_ccw, iova, len);
-	if (ret) {
-		ccwchain_free(chain);
-		return ret;
-	}
-
-	/* Now loop for its TICs. */
-	ret = ccwchain_loop_tic(chain, cp);
+	/* Build a ccwchain for the first CCW segment */
+	ret = ccwchain_handle_ccw(orb->cmd.cpa, cp);
 	if (ret)
 		cp_free(cp);
+
 	/* It is safe to force: if not set but idals used
 	 * ccwchain_calc_length returns an error.
 	 */