[SCSI] libsas: fix scr_read/write users and update the libata documentation

This fixes up the usage in libsas (which are easy to miss, since they're
only in the scsi-misc tree) ... and also corrects the documentation on
the point of what these two function pointers actually return.

Signed-off-by: James Bottomley <[e-mail]>

Documentation/DocBook/libata.tmpl

···
 
 	<sect2><title>SATA phy read/write</title>
 	<programlisting>
-u32 (*scr_read) (struct ata_port *ap, unsigned int sc_reg);
-void (*scr_write) (struct ata_port *ap, unsigned int sc_reg,
+int (*scr_read) (struct ata_port *ap, unsigned int sc_reg,
+		 u32 *val);
+int (*scr_write) (struct ata_port *ap, unsigned int sc_reg,
                    u32 val);
 	</programlisting>
 

drivers/scsi/libsas/sas_ata.c

···
 		qc->tf.nsect = 0;
 	}
 
-	ata_tf_to_fis(&qc->tf, (u8*)&task->ata_task.fis, 0);
+	ata_tf_to_fis(&qc->tf, 1, 0, (u8*)&task->ata_task.fis);
 	task->uldd_task = qc;
 	if (is_atapi_taskfile(&qc->tf)) {
 		memcpy(task->ata_task.atapi_packet, qc->cdb, qc->dev->cdb_len);
···
 	memcpy(tf, &dev->sata_dev.tf, sizeof (*tf));
 }
 
-static void sas_ata_scr_write(struct ata_port *ap, unsigned int sc_reg_in,
+static int sas_ata_scr_write(struct ata_port *ap, unsigned int sc_reg_in,
 			      u32 val)
 {
 	struct domain_device *dev = ap->private_data;
···
 		case SCR_ACTIVE:
 			dev->sata_dev.ap->sactive = val;
 			break;
+		default:
+			return -EINVAL;
 	}
+	return 0;
 }
 
-static u32 sas_ata_scr_read(struct ata_port *ap, unsigned int sc_reg_in)
+static int sas_ata_scr_read(struct ata_port *ap, unsigned int sc_reg_in,
+			    u32 *val)
 {
 	struct domain_device *dev = ap->private_data;
 
 	SAS_DPRINTK("STUB %s\n", __FUNCTION__);
 	switch (sc_reg_in) {
 		case SCR_STATUS:
-			return dev->sata_dev.sstatus;
+			*val = dev->sata_dev.sstatus;
+			return 0;
 		case SCR_CONTROL:
-			return dev->sata_dev.scontrol;
+			*val = dev->sata_dev.scontrol;
+			return 0;
 		case SCR_ERROR:
-			return dev->sata_dev.serror;
+			*val = dev->sata_dev.serror;
+			return 0;
 		case SCR_ACTIVE:
-			return dev->sata_dev.ap->sactive;
+			*val = dev->sata_dev.ap->sactive;
+			return 0;
 		default:
-			return 0xffffffffU;
+			return -EINVAL;
 	}
 }