libata: replace tf_read with qc_fill_rtf for non-SFF drivers

Now that all SFF stuff is separated out of core layer, core layer
doesn't call ops->tf_read directly.  It gets called only via
ops->qc_fill_rtf() for non-SFF drivers.  This patch directly
implements private ops->qc_fill_rtf() for non-SFF controllers and kill
ops->tf_read().

This is much cleaner for non-SFF controllers as some of them have to
cache SFF register values in private data structure and report the
cached values via ops->tf_read().  Also, ops->tf_read() gets nasty for
controllers which don't have clear notion of TF registers when
operation is not in progress.

As this change makes default ops->qc_fill_rtf unnecessary, move
ata_sff_qc_fill_rtf() form ata_base_port_ops to ata_sff_port_ops where
it belongs.

Signed-off-by: Tejun Heo <htejun@gmail.com>
diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index 2ec2558..e81f2fd 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -225,6 +225,14 @@
 	return 0;
 }
 
+static bool sas_ata_qc_fill_rtf(struct ata_queued_cmd *qc)
+{
+	struct domain_device *dev = qc->ap->private_data;
+
+	memcpy(&qc->result_tf, &dev->sata_dev.tf, sizeof(qc->result_tf));
+	return true;
+}
+
 static u8 sas_ata_check_status(struct ata_port *ap)
 {
 	struct domain_device *dev = ap->private_data;
@@ -292,12 +300,6 @@
 	}
 }
 
-static void sas_ata_tf_read(struct ata_port *ap, struct ata_taskfile *tf)
-{
-	struct domain_device *dev = ap->private_data;
-	memcpy(tf, &dev->sata_dev.tf, sizeof (*tf));
-}
-
 static int sas_ata_scr_write(struct ata_port *ap, unsigned int sc_reg_in,
 			      u32 val)
 {
@@ -353,10 +355,9 @@
 	.sff_dev_select		= ata_noop_dev_select,
 	.phy_reset		= sas_ata_phy_reset,
 	.post_internal_cmd	= sas_ata_post_internal,
-	.sff_tf_read		= sas_ata_tf_read,
 	.qc_prep		= ata_noop_qc_prep,
 	.qc_issue		= sas_ata_qc_issue,
-	.qc_fill_rtf		= ata_sff_qc_fill_rtf,
+	.qc_fill_rtf		= sas_ata_qc_fill_rtf,
 	.port_start		= ata_sas_port_start,
 	.port_stop		= ata_sas_port_stop,
 	.scr_read		= sas_ata_scr_read,