[PATCH] libata: ACPI and _GTF support

_GTF is an acpi method that is used to reinitialize the drive.  It returns
a task file containing ata commands that are sent back to the drive to restore
it to boot up defaults.

Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
(cherry picked from 9c69cab24b51a89664f4c0dfaf8a436d32117624 commit)

drivers/ata/libata.h

@@ -47,6 +47,7 @@ extern struct workqueue_struct *ata_aux_wq;
 extern int atapi_enabled;
 extern int atapi_dmadir;
 extern int libata_fua;
+extern int noacpi;
 extern struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev);
 extern int ata_build_rw_tf(struct ata_taskfile *tf, struct ata_device *dev,
 			   u64 block, u32 n_block, unsigned int tf_flags,
@@ -87,6 +88,15 @@ extern void ata_port_init(struct ata_port *ap, struct ata_host *host,
 extern struct ata_probe_ent *ata_probe_ent_alloc(struct device *dev,
 						 const struct ata_port_info *port);
 
+/* libata-acpi.c */
+#ifdef CONFIG_SATA_ACPI
+extern int ata_acpi_exec_tfs(struct ata_port *ap);
+#else
+static inline int ata_acpi_exec_tfs(struct ata_port *ap)
+{
+	return 0;
+}
+#endif
 
 /* libata-scsi.c */
 extern struct scsi_transport_template ata_scsi_transport_template;