IB/ipath: Add ability to set and clear IB local loopback

This is a sticky state.  It is useful for diagnosing problems with
boards versus cable/switch problems.
Signed-off-by: Dave Olson <dave.olson@qlogic.com>
Signed-off-by: Bryan O'Sullivan <bryan.osullivan@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/ipath/ipath_common.h

@@ -78,6 +78,8 @@
 #define IPATH_IB_LINKINIT		3
 #define IPATH_IB_LINKDOWN_SLEEP		4
 #define IPATH_IB_LINKDOWN_DISABLE	5
+#define IPATH_IB_LINK_LOOPBACK	6 /* enable local loopback */
+#define IPATH_IB_LINK_EXTERNAL	7 /* normal, disable local loopback */
 
 /*
  * stats maintained by the driver.  For now, at least, this is global

drivers/infiniband/hw/ipath/ipath_driver.c

@@ -1662,6 +1662,22 @@ int ipath_set_linkstate(struct ipath_devdata *dd, u8 newstate)
 		lstate = IPATH_LINKACTIVE;
 		break;
 
+	case IPATH_IB_LINK_LOOPBACK:
+		dev_info(&dd->pcidev->dev, "Enabling IB local loopback\n");
+		dd->ipath_ibcctrl |= INFINIPATH_IBCC_LOOPBACK;
+		ipath_write_kreg(dd, dd->ipath_kregs->kr_ibcctrl,
+				 dd->ipath_ibcctrl);
+		ret = 0;
+		goto bail; // no state change to wait for
+
+	case IPATH_IB_LINK_EXTERNAL:
+		dev_info(&dd->pcidev->dev, "Disabling IB local loopback (normal)\n");
+		dd->ipath_ibcctrl &= ~INFINIPATH_IBCC_LOOPBACK;
+		ipath_write_kreg(dd, dd->ipath_kregs->kr_ibcctrl,
+				 dd->ipath_ibcctrl);
+		ret = 0;
+		goto bail; // no state change to wait for
+
 	default:
 		ipath_dbg("Invalid linkstate 0x%x requested\n", newstate);
 		ret = -EINVAL;