libata-pmp-prep: implement sata_async_notification()

AN serves multiple purposes.  For ATAPI, it's used for media change
notification.  For PMP, for downstream PHY status change notification.
Implement sata_async_notification() which demultiplexes AN.

To avoid unnecessary port events, ATAPI AN is not enabled if PMP is
attached but SNTF is not available.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Kriten Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 73 insertions, 0 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 3c31e10caf21..60186f8ac3a1 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -905,6 +905,79 @@ int ata_port_freeze(struct ata_port *ap)
 }
 
 /**
+ *      sata_async_notification - SATA async notification handler
+ *      @ap: ATA port where async notification is received
+ *
+ *      Handler to be called when async notification via SDB FIS is
+ *      received.  This function schedules EH if necessary.
+ *
+ *      LOCKING:
+ *      spin_lock_irqsave(host lock)
+ *
+ *      RETURNS:
+ *      1 if EH is scheduled, 0 otherwise.
+ */
+int sata_async_notification(struct ata_port *ap)
+{
+        u32 sntf;
+        int rc;
+
+        if (!(ap->flags & ATA_FLAG_AN))
+                return 0;
+
+        rc = sata_scr_read(&ap->link, SCR_NOTIFICATION, &sntf);
+        if (rc == 0)
+                sata_scr_write(&ap->link, SCR_NOTIFICATION, sntf);
+
+        if (!ap->nr_pmp_links || rc) {
+                /* PMP is not attached or SNTF is not available */
+                if (!ap->nr_pmp_links) {
+                        /* PMP is not attached.  Check whether ATAPI
+                         * AN is configured.  If so, notify media
+                         * change.
+                         */
+                        struct ata_device *dev = ap->link.device;
+
+                        if ((dev->class == ATA_DEV_ATAPI) &&
+                            (dev->flags & ATA_DFLAG_AN))
+                                ata_scsi_media_change_notify(dev);
+                        return 0;
+                } else {
+                        /* PMP is attached but SNTF is not available.
+                         * ATAPI async media change notification is
+                         * not used.  The PMP must be reporting PHY
+                         * status change, schedule EH.
+                         */
+                        ata_port_schedule_eh(ap);
+                        return 1;
+                }
+        } else {
+                /* PMP is attached and SNTF is available */
+                struct ata_link *link;
+
+                /* check and notify ATAPI AN */
+                ata_port_for_each_link(link, ap) {
+                        if (!(sntf & (1 << link->pmp)))
+                                continue;
+
+                        if ((link->device->class == ATA_DEV_ATAPI) &&
+                            (link->device->flags & ATA_DFLAG_AN))
+                                ata_scsi_media_change_notify(link->device);
+                }
+
+                /* If PMP is reporting that PHY status of some
+                 * downstream ports has changed, schedule EH.
+                 */
+                if (sntf & (1 << SATA_PMP_CTRL_PORT)) {
+                        ata_port_schedule_eh(ap);
+                        return 1;
+                }
+
+                return 0;
+        }
+}
+
+/**
  *      ata_eh_freeze_port - EH helper to freeze port
  *      @ap: ATA port to freeze
  *