rapidio: add handling of orphan port-write message

Add check for access to port-write (PW) message source device before
processing the PW message.  If source RIO device is not available (power
down or RIO link failure) trace back to a last available switch/port on
the PW message route and service failure at that point.

Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Thomas Moll <thomas.moll@sysgo.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Li Yang <leoli@freescale.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Micha Nelissen <micha@neli.hopto.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 110 insertions, 5 deletions

diff --git a/drivers/rapidio/rio.c b/drivers/rapidio/rio.c
index 77bd4165238f..aefc2a0004d4 100644
--- a/drivers/rapidio/rio.c
+++ b/drivers/rapidio/rio.c
@@ -495,6 +495,92 @@ int rio_set_port_lockout(struct rio_dev *rdev, u32 pnum, int lock)
 }
 
 /**
+ * rio_chk_dev_route - Validate route to the specified device.
+ * @rdev:  RIO device failed to respond
+ * @nrdev: Last active device on the route to rdev
+ * @npnum: nrdev's port number on the route to rdev
+ *
+ * Follows a route to the specified RIO device to determine the last available
+ * device (and corresponding RIO port) on the route.
+ */
+static int
+rio_chk_dev_route(struct rio_dev *rdev, struct rio_dev **nrdev, int *npnum)
+{
+        u32 result;
+        int p_port, rc = -EIO;
+        struct rio_dev *prev = NULL;
+
+        /* Find switch with failed RIO link */
+        while (rdev->prev && (rdev->prev->pef & RIO_PEF_SWITCH)) {
+                if (!rio_read_config_32(rdev->prev, RIO_DEV_ID_CAR, &result)) {
+                        prev = rdev->prev;
+                        break;
+                }
+                rdev = rdev->prev;
+        }
+
+        if (prev == NULL)
+                goto err_out;
+
+        /* Find port with failed RIO link */
+        for (p_port = 0;
+             p_port < RIO_GET_TOTAL_PORTS(prev->swpinfo); p_port++)
+                if (prev->rswitch->nextdev[p_port] == rdev)
+                        break;
+
+        if (p_port < RIO_GET_TOTAL_PORTS(prev->swpinfo)) {
+                pr_debug("RIO: link failed on [%s]-P%d\n",
+                         rio_name(prev), p_port);
+                *nrdev = prev;
+                *npnum = p_port;
+                rc = 0;
+        } else
+                pr_debug("RIO: failed to trace route to %s\n", rio_name(prev));
+err_out:
+        return rc;
+}
+
+/**
+ * rio_mport_chk_dev_access - Validate access to the specified device.
+ * @mport: Master port to send transactions
+ * @destid: Device destination ID in network
+ * @hopcount: Number of hops into the network
+ */
+static int
+rio_mport_chk_dev_access(struct rio_mport *mport, u16 destid, u8 hopcount)
+{
+        int i = 0;
+        u32 tmp;
+
+        while (rio_mport_read_config_32(mport, destid, hopcount,
+                                        RIO_DEV_ID_CAR, &tmp)) {
+                i++;
+                if (i == RIO_MAX_CHK_RETRY)
+                        return -EIO;
+                mdelay(1);
+        }
+
+        return 0;
+}
+
+/**
+ * rio_chk_dev_access - Validate access to the specified device.
+ * @rdev: Pointer to RIO device control structure
+ */
+static int rio_chk_dev_access(struct rio_dev *rdev)
+{
+        u8 hopcount = 0xff;
+        u16 destid = rdev->destid;
+
+        if (rdev->rswitch) {
+                destid = rdev->rswitch->destid;
+                hopcount = rdev->rswitch->hopcount;
+        }
+
+        return rio_mport_chk_dev_access(rdev->net->hport, destid, hopcount);
+}
+
+/**
  * rio_get_input_status - Sends a Link-Request/Input-Status control symbol and
  *                        returns link-response (if requested).
  * @rdev: RIO devive to issue Input-status command
@@ -654,8 +740,8 @@ int rio_inb_pwrite_handler(union rio_pw_msg *pw_msg)
 
         rdev = rio_get_comptag(pw_msg->em.comptag, NULL);
         if (rdev == NULL) {
-                /* Someting bad here (probably enumeration error) */
-                pr_err("RIO: %s No matching device for CTag 0x%08x\n",
+                /* Device removed or enumeration error */
+                pr_debug("RIO: %s No matching device for CTag 0x%08x\n",
                         __func__, pw_msg->em.comptag);
                 return -EIO;
         }
@@ -686,6 +772,26 @@ int rio_inb_pwrite_handler(union rio_pw_msg *pw_msg)
                         return 0;
         }
 
+        portnum = pw_msg->em.is_port & 0xFF;
+
+        /* Check if device and route to it are functional:
+         * Sometimes devices may send PW message(s) just before being
+         * powered down (or link being lost).
+         */
+        if (rio_chk_dev_access(rdev)) {
+                pr_debug("RIO: device access failed - get link partner\n");
+                /* Scan route to the device and identify failed link.
+                 * This will replace device and port reported in PW message.
+                 * PW message should not be used after this point.
+                 */
+                if (rio_chk_dev_route(rdev, &rdev, &portnum)) {
+                        pr_err("RIO: Route trace for %s failed\n",
+                                rio_name(rdev));
+                        return -EIO;
+                }
+                pw_msg = NULL;
+        }
+
         /* For End-point devices processing stops here */
         if (!(rdev->pef & RIO_PEF_SWITCH))
                 return 0;
@@ -703,9 +809,6 @@ int rio_inb_pwrite_handler(union rio_pw_msg *pw_msg)
         /*
          * Process the port-write notification from switch
          */
-
-        portnum = pw_msg->em.is_port & 0xFF;
-
         if (rdev->rswitch->em_handle)
                 rdev->rswitch->em_handle(rdev, portnum);
 
diff --git a/drivers/rapidio/rio.h b/drivers/rapidio/rio.h
index f27b7a9c47d2..bc71ba1d239e 100644
--- a/drivers/rapidio/rio.h
+++ b/drivers/rapidio/rio.h
@@ -14,6 +14,8 @@
 #include <linux/list.h>
 #include <linux/rio.h>
 
+#define RIO_MAX_CHK_RETRY       3
+
 /* Functions internal to the RIO core code */
 
 extern u32 rio_mport_get_feature(struct rio_mport *mport, int local, u16 destid,