[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, 59 insertions, 10 deletions

diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index 3e9dc1a..a0c3003 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -24,6 +24,7 @@
 
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
+#include <linux/async.h>
 #include <scsi/scsi_host.h>
 #include <scsi/scsi_eh.h>
 #include "sas_internal.h"
@@ -180,16 +181,18 @@ int sas_notify_lldd_dev_found(struct domain_device *dev)
 	struct Scsi_Host *shost = sas_ha->core.shost;
 	struct sas_internal *i = to_sas_internal(shost->transportt);
 
-	if (i->dft->lldd_dev_found) {
-		res = i->dft->lldd_dev_found(dev);
-		if (res) {
-			printk("sas: driver on pcidev %s cannot handle "
-			       "device %llx, error:%d\n",
-			       dev_name(sas_ha->dev),
-			       SAS_ADDR(dev->sas_addr), res);
-		}
-		kref_get(&dev->kref);
+	if (!i->dft->lldd_dev_found)
+		return 0;
+
+	res = i->dft->lldd_dev_found(dev);
+	if (res) {
+		printk("sas: driver on pcidev %s cannot handle "
+		       "device %llx, error:%d\n",
+		       dev_name(sas_ha->dev),
+		       SAS_ADDR(dev->sas_addr), res);
 	}
+	set_bit(SAS_DEV_FOUND, &dev->state);
+	kref_get(&dev->kref);
 	return res;
 }
 
@@ -200,7 +203,10 @@ void sas_notify_lldd_dev_gone(struct domain_device *dev)
 	struct Scsi_Host *shost = sas_ha->core.shost;
 	struct sas_internal *i = to_sas_internal(shost->transportt);
 
-	if (i->dft->lldd_dev_gone) {
+	if (!i->dft->lldd_dev_gone)
+		return;
+
+	if (test_and_clear_bit(SAS_DEV_FOUND, &dev->state)) {
 		i->dft->lldd_dev_gone(dev);
 		sas_put_device(dev);
 	}
@@ -234,6 +240,47 @@ static void sas_probe_devices(struct work_struct *work)
 	}
 }
 
+static void sas_suspend_devices(struct work_struct *work)
+{
+	struct asd_sas_phy *phy;
+	struct domain_device *dev;
+	struct sas_discovery_event *ev = to_sas_discovery_event(work);
+	struct asd_sas_port *port = ev->port;
+	struct Scsi_Host *shost = port->ha->core.shost;
+	struct sas_internal *si = to_sas_internal(shost->transportt);
+
+	clear_bit(DISCE_SUSPEND, &port->disc.pending);
+
+	sas_suspend_sata(port);
+
+	/* lldd is free to forget the domain_device across the
+	 * suspension, we force the issue here to keep the reference
+	 * counts aligned
+	 */
+	list_for_each_entry(dev, &port->dev_list, dev_list_node)
+		sas_notify_lldd_dev_gone(dev);
+
+	/* we are suspending, so we know events are disabled and
+	 * phy_list is not being mutated
+	 */
+	list_for_each_entry(phy, &port->phy_list, port_phy_el) {
+		if (si->dft->lldd_port_formed)
+			si->dft->lldd_port_deformed(phy);
+		phy->suspended = 1;
+		port->suspended = 1;
+	}
+}
+
+static void sas_resume_devices(struct work_struct *work)
+{
+	struct sas_discovery_event *ev = to_sas_discovery_event(work);
+	struct asd_sas_port *port = ev->port;
+
+	clear_bit(DISCE_RESUME, &port->disc.pending);
+
+	sas_resume_sata(port);
+}
+
 /**
  * sas_discover_end_dev -- discover an end device (SSP, etc)
  * @end: pointer to domain device of interest
@@ -530,6 +577,8 @@ void sas_init_disc(struct sas_discovery *disc, struct asd_sas_port *port)
 		[DISCE_DISCOVER_DOMAIN] = sas_discover_domain,
 		[DISCE_REVALIDATE_DOMAIN] = sas_revalidate_domain,
 		[DISCE_PROBE] = sas_probe_devices,
+		[DISCE_SUSPEND] = sas_suspend_devices,
+		[DISCE_RESUME] = sas_resume_devices,
 		[DISCE_DESTRUCT] = sas_destruct_devices,
 	};