libata-pmp: implement qc_defer for command switching PMP support
Implement sata_pmp_qc_defer_cmd_switch() - standard qc_defer for
command switching PMP support.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/libata-pmp.c b/drivers/ata/libata-pmp.c
index eeffce6..f6c4b11 100644
--- a/drivers/ata/libata-pmp.c
+++ b/drivers/ata/libata-pmp.c
@@ -70,6 +70,36 @@
}
/**
+ * sata_pmp_qc_defer_cmd_switch - qc_defer for command switching PMP
+ * @qc: ATA command in question
+ *
+ * A host which has command switching PMP support cannot issue
+ * commands to multiple links simultaneously.
+ *
+ * LOCKING:
+ * spin_lock_irqsave(host lock)
+ *
+ * RETURNS:
+ * ATA_DEFER_* if deferring is needed, 0 otherwise.
+ */
+int sata_pmp_qc_defer_cmd_switch(struct ata_queued_cmd *qc)
+{
+ struct ata_link *link = qc->dev->link;
+ struct ata_port *ap = link->ap;
+
+ if (ap->excl_link == NULL || ap->excl_link == link) {
+ if (ap->nr_active_links == 0 || ata_link_active(link)) {
+ qc->flags |= ATA_QCFLAG_CLEAR_EXCL;
+ return ata_std_qc_defer(qc);
+ }
+
+ ap->excl_link = link;
+ }
+
+ return ATA_DEFER_PORT;
+}
+
+/**
* sata_pmp_read_init_tf - initialize TF for PMP read
* @tf: taskfile to initialize
* @dev: PMP dev