rapidio: add switch locking during discovery

Add switch access locking during RapidIO discovery.  Access lock is
required when reading switch routing table contents due to indexed
mechanism of RT addressing.

Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Tested-by: 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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 144 insertions, 20 deletions

diff --git a/drivers/rapidio/rio-scan.c b/drivers/rapidio/rio-scan.c
index 7f1a675d835d..cbf0d5f4fba8 100644
--- a/drivers/rapidio/rio-scan.c
+++ b/drivers/rapidio/rio-scan.c
@@ -457,12 +457,87 @@ rio_sport_is_active(struct rio_mport *port, u16 destid, u8 hopcount, int sport)
 }
 
 /**
+ * rio_lock_device - Acquires host device lock for specified device
+ * @port: Master port to send transaction
+ * @destid: Destination ID for device/switch
+ * @hopcount: Hopcount to reach switch
+ * @wait_ms: Max wait time in msec (0 = no timeout)
+ *
+ * Attepts to acquire host device lock for specified device
+ * Returns 0 if device lock acquired or EINVAL if timeout expires.
+ */
+static int
+rio_lock_device(struct rio_mport *port, u16 destid, u8 hopcount, int wait_ms)
+{
+        u32 result;
+        int tcnt = 0;
+
+        /* Attempt to acquire device lock */
+        rio_mport_write_config_32(port, destid, hopcount,
+                                  RIO_HOST_DID_LOCK_CSR, port->host_deviceid);
+        rio_mport_read_config_32(port, destid, hopcount,
+                                 RIO_HOST_DID_LOCK_CSR, &result);
+
+        while (result != port->host_deviceid) {
+                if (wait_ms != 0 && tcnt == wait_ms) {
+                        pr_debug("RIO: timeout when locking device %x:%x\n",
+                                destid, hopcount);
+                        return -EINVAL;
+                }
+
+                /* Delay a bit */
+                mdelay(1);
+                tcnt++;
+                /* Try to acquire device lock again */
+                rio_mport_write_config_32(port, destid,
+                        hopcount,
+                        RIO_HOST_DID_LOCK_CSR,
+                        port->host_deviceid);
+                rio_mport_read_config_32(port, destid,
+                        hopcount,
+                        RIO_HOST_DID_LOCK_CSR, &result);
+        }
+
+        return 0;
+}
+
+/**
+ * rio_unlock_device - Releases host device lock for specified device
+ * @port: Master port to send transaction
+ * @destid: Destination ID for device/switch
+ * @hopcount: Hopcount to reach switch
+ *
+ * Returns 0 if device lock released or EINVAL if fails.
+ */
+static int
+rio_unlock_device(struct rio_mport *port, u16 destid, u8 hopcount)
+{
+        u32 result;
+
+        /* Release device lock */
+        rio_mport_write_config_32(port, destid,
+                                  hopcount,
+                                  RIO_HOST_DID_LOCK_CSR,
+                                  port->host_deviceid);
+        rio_mport_read_config_32(port, destid, hopcount,
+                RIO_HOST_DID_LOCK_CSR, &result);
+        if ((result & 0xffff) != 0xffff) {
+                pr_debug("RIO: badness when releasing device lock %x:%x\n",
+                         destid, hopcount);
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
+/**
  * rio_route_add_entry- Add a route entry to a switch routing table
  * @mport: Master port to send transaction
  * @rswitch: Switch device
  * @table: Routing table ID
  * @route_destid: Destination ID to be routed
  * @route_port: Port number to be routed
+ * @lock: lock switch device flag
  *
  * Calls the switch specific add_entry() method to add a route entry
  * on a switch. The route table can be specified using the @table
@@ -471,12 +546,26 @@ rio_sport_is_active(struct rio_mport *port, u16 destid, u8 hopcount, int sport)
  * %RIO_GLOBAL_TABLE in @table. Returns %0 on success or %-EINVAL
  * on failure.
  */
-static int rio_route_add_entry(struct rio_mport *mport, struct rio_switch *rswitch,
-                               u16 table, u16 route_destid, u8 route_port)
+static int
+rio_route_add_entry(struct rio_mport *mport, struct rio_switch *rswitch,
+                    u16 table, u16 route_destid, u8 route_port, int lock)
 {
-        return rswitch->add_entry(mport, rswitch->destid,
+        int rc;
+
+        if (lock) {
+                rc = rio_lock_device(mport, rswitch->destid,
+                                     rswitch->hopcount, 1000);
+                if (rc)
+                        return rc;
+        }
+
+        rc = rswitch->add_entry(mport, rswitch->destid,
                                         rswitch->hopcount, table,
                                         route_destid, route_port);
+        if (lock)
+                rio_unlock_device(mport, rswitch->destid, rswitch->hopcount);
+
+        return rc;
 }
 
 /**
@@ -486,6 +575,7 @@ static int rio_route_add_entry(struct rio_mport *mport, struct rio_switch *rswit
  * @table: Routing table ID
  * @route_destid: Destination ID to be routed
  * @route_port: Pointer to read port number into
+ * @lock: lock switch device flag
  *
  * Calls the switch specific get_entry() method to read a route entry
  * in a switch. The route table can be specified using the @table
@@ -496,11 +586,24 @@ static int rio_route_add_entry(struct rio_mport *mport, struct rio_switch *rswit
  */
 static int
 rio_route_get_entry(struct rio_mport *mport, struct rio_switch *rswitch, u16 table,
-                    u16 route_destid, u8 * route_port)
+                    u16 route_destid, u8 *route_port, int lock)
 {
-        return rswitch->get_entry(mport, rswitch->destid,
+        int rc;
+
+        if (lock) {
+                rc = rio_lock_device(mport, rswitch->destid,
+                                     rswitch->hopcount, 1000);
+                if (rc)
+                        return rc;
+        }
+
+        rc = rswitch->get_entry(mport, rswitch->destid,
                                         rswitch->hopcount, table,
                                         route_destid, route_port);
+        if (lock)
+                rio_unlock_device(mport, rswitch->destid, rswitch->hopcount);
+
+        return rc;
 }
 
 /**
@@ -640,14 +743,14 @@ static int __devinit rio_enum_peer(struct rio_net *net, struct rio_mport *port,
                 sw_inport = rio_get_swpinfo_inport(port,
                                 RIO_ANY_DESTID(port->sys_size), hopcount);
                 rio_route_add_entry(port, rdev->rswitch, RIO_GLOBAL_TABLE,
-                                    port->host_deviceid, sw_inport);
+                                    port->host_deviceid, sw_inport, 0);
                 rdev->rswitch->route_table[port->host_deviceid] = sw_inport;
 
                 for (destid = 0; destid < next_destid; destid++) {
                         if (destid == port->host_deviceid)
                                 continue;
                         rio_route_add_entry(port, rdev->rswitch, RIO_GLOBAL_TABLE,
-                                            destid, sw_inport);
+                                            destid, sw_inport, 0);
                         rdev->rswitch->route_table[destid] = sw_inport;
                 }
 
@@ -673,7 +776,7 @@ static int __devinit rio_enum_peer(struct rio_net *net, struct rio_mport *port,
                                 rio_route_add_entry(port, rdev->rswitch,
                                                 RIO_GLOBAL_TABLE,
                                                 RIO_ANY_DESTID(port->sys_size),
-                                                port_num);
+                                                port_num, 0);
 
                                 if (rio_enum_peer(net, port, hopcount + 1) < 0)
                                         return -1;
@@ -687,7 +790,8 @@ static int __devinit rio_enum_peer(struct rio_net *net, struct rio_mport *port,
                                                 rio_route_add_entry(port, rdev->rswitch,
                                                                     RIO_GLOBAL_TABLE,
                                                                     destid,
-                                                                    port_num);
+                                                                    port_num,
+                                                                    0);
                                                 rdev->rswitch->
                                                     route_table[destid] =
                                                     port_num;
@@ -778,17 +882,21 @@ rio_disc_peer(struct rio_net *net, struct rio_mport *port, u16 destid,
                                 pr_debug(
                                     "RIO: scanning device on port %d\n",
                                     port_num);
+
+                                rio_lock_device(port, destid, hopcount, 1000);
+
                                 for (ndestid = 0;
                                      ndestid < RIO_ANY_DESTID(port->sys_size);
                                      ndestid++) {
                                         rio_route_get_entry(port, rdev->rswitch,
                                                             RIO_GLOBAL_TABLE,
                                                             ndestid,
-                                                            &route_port);
+                                                            &route_port, 0);
                                         if (route_port == port_num)
                                                 break;
                                 }
 
+                                rio_unlock_device(port, destid, hopcount);
                                 if (rio_disc_peer
                                     (net, port, ndestid, hopcount + 1) < 0)
                                         return -1;
@@ -889,7 +997,9 @@ static void rio_update_route_tables(struct rio_mport *port)
                                                 rswitch->destid, rswitch->hopcount);
 
                                 if (rswitch->add_entry) {
-                                        rio_route_add_entry(port, rswitch, RIO_GLOBAL_TABLE, destid, sport);
+                                        rio_route_add_entry(port, rswitch,
+                                                RIO_GLOBAL_TABLE, destid,
+                                                sport, 0);
                                         rswitch->route_table[destid] = sport;
                                 }
                         }
@@ -963,15 +1073,22 @@ static void rio_build_route_tables(void)
         u8 sport;
 
         list_for_each_entry(rdev, &rio_devices, global_list)
-            if (rio_is_switch(rdev))
-                for (i = 0;
-                     i < RIO_MAX_ROUTE_ENTRIES(rdev->net->hport->sys_size);
-                     i++) {
-                        if (rio_route_get_entry
-                            (rdev->net->hport, rdev->rswitch, RIO_GLOBAL_TABLE,
-                             i, &sport) < 0)
-                                continue;
-                        rdev->rswitch->route_table[i] = sport;
+                if (rio_is_switch(rdev)) {
+                        rio_lock_device(rdev->net->hport, rdev->rswitch->destid,
+                                        rdev->rswitch->hopcount, 1000);
+                        for (i = 0;
+                             i < RIO_MAX_ROUTE_ENTRIES(rdev->net->hport->sys_size);
+                             i++) {
+                                if (rio_route_get_entry
+                                    (rdev->net->hport, rdev->rswitch,
+                                     RIO_GLOBAL_TABLE, i, &sport, 0) < 0)
+                                        continue;
+                                rdev->rswitch->route_table[i] = sport;
+                        }
+
+                        rio_unlock_device(rdev->net->hport,
+                                          rdev->rswitch->destid,
+                                          rdev->rswitch->hopcount);
                 }
 }
 
@@ -1030,6 +1147,13 @@ int __devinit rio_disc_mport(struct rio_mport *mport)
                 del_timer_sync(&rio_enum_timer);
 
                 pr_debug("done\n");
+
+                /* Read DestID assigned by enumerator */
+                rio_local_read_config_32(mport, RIO_DID_CSR,
+                                         &mport->host_deviceid);
+                mport->host_deviceid = RIO_GET_DID(mport->sys_size,
+                                                   mport->host_deviceid);
+
                 if (rio_disc_peer(net, mport, RIO_ANY_DESTID(mport->sys_size),
                                         0) < 0) {
                         printk(KERN_INFO