[SCSI] libsas: suspend / resume support

libsas power management routines to suspend and recover the sas domain
based on a model where the lldd is allowed and expected to be
"forgetful".

sas_suspend_ha - disable event processing allowing the lldd to take down
                 links without concern for causing hotplug events.
                 Regardless of whether the lldd actually posts link down
                 messages libsas notifies the lldd that all
                 domain_devices are gone.

sas_prep_resume_ha - on the way back up before the lldd starts link
                     training clean out any spurious events that were
                     generated on the way down, and re-enable event
                     processing

sas_resume_ha - after the lldd has started and decided that all phys
		have posted link-up events this routine is called to let
		libsas start it's own timeout of any phys that did not
		resume.  After the timeout an lldd can cancel the
                phy teardown by posting a link-up event.

Storage for ex_change_count (u16) and phy_change_count (u8) are changed
to int so they can be set to -1 to indicate 'invalidated'.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jacek Danecki <jacek.danecki@intel.com>
Tested-by: Maciej Patelczyk <maciej.patelczyk@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 51 insertions, 1 deletions

diff --git a/drivers/scsi/libsas/sas_port.c b/drivers/scsi/libsas/sas_port.c
index e884a8c58a0c..1398b714c018 100644
--- a/drivers/scsi/libsas/sas_port.c
+++ b/drivers/scsi/libsas/sas_port.c
@@ -39,6 +39,49 @@ static bool phy_is_wideport_member(struct asd_sas_port *port, struct asd_sas_phy
 	return true;
 }
 
+static void sas_resume_port(struct asd_sas_phy *phy)
+{
+	struct domain_device *dev;
+	struct asd_sas_port *port = phy->port;
+	struct sas_ha_struct *sas_ha = phy->ha;
+	struct sas_internal *si = to_sas_internal(sas_ha->core.shost->transportt);
+
+	if (si->dft->lldd_port_formed)
+		si->dft->lldd_port_formed(phy);
+
+	if (port->suspended)
+		port->suspended = 0;
+	else {
+		/* we only need to handle "link returned" actions once */
+		return;
+	}
+
+	/* if the port came back:
+	 * 1/ presume every device came back
+	 * 2/ force the next revalidation to check all expander phys
+	 */
+	list_for_each_entry(dev, &port->dev_list, dev_list_node) {
+		int i, rc;
+
+		rc = sas_notify_lldd_dev_found(dev);
+		if (rc) {
+			sas_unregister_dev(port, dev);
+			continue;
+		}
+
+		if (dev->dev_type == EDGE_DEV || dev->dev_type == FANOUT_DEV) {
+			dev->ex_dev.ex_change_count = -1;
+			for (i = 0; i < dev->ex_dev.num_phys; i++) {
+				struct ex_phy *phy = &dev->ex_dev.ex_phy[i];
+
+				phy->phy_change_count = -1;
+			}
+		}
+	}
+
+	sas_discover_event(port, DISCE_RESUME);
+}
+
 /**
  * sas_form_port -- add this phy to a port
  * @phy: the phy of interest
@@ -58,7 +101,14 @@ static void sas_form_port(struct asd_sas_phy *phy)
 	if (port) {
 		if (!phy_is_wideport_member(port, phy))
 			sas_deform_port(phy, 0);
-		else {
+		else if (phy->suspended) {
+			phy->suspended = 0;
+			sas_resume_port(phy);
+
+			/* phy came back, try to cancel the timeout */
+			wake_up(&sas_ha->eh_wait_q);
+			return;
+		} else {
 			SAS_DPRINTK("%s: phy%d belongs to port%d already(%d)!\n",
 				    __func__, phy->id, phy->port->id,
 				    phy->port->num_phys);