rapidio/rionet: add capability to change MTU

These patches are the result of extensive collaboration within the
RapidIO.org Software Task Group between Texas Instruments, Freescale,
Prodrive Technologies, Nokia Networks, BAE and IDT.  Additional input
was received from other members of RapidIO.org.  The objective was to
create a character mode driver interface which exposes the capabilities
of RapidIO devices directly to applications, in a manner that allows the
numerous and varied RapidIO implementations to interoperate.

The Software Task Group has also developed fabric management, Remote
Memory Access, and sockets applications which make use of these
interfaces in user space.  Intensive testing with these applications
prompted the RapidIO subsystem updates provided within this set of
patches.

This patch (of 29):

Replace default Ethernet-specific routine by the custom one to allow
setting of larger MTU supported by RapidIO messaging (max RIO packet
size is 4096 bytes).

Signed-off-by: Aurelien Jacquiot <a-jacquiot@ti.com>
Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Andre van Herk <andre.van.herk@prodrive-technologies.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/net/rionet.c

@@ -48,6 +48,8 @@ MODULE_LICENSE("GPL");
 #define RIONET_TX_RING_SIZE	CONFIG_RIONET_TX_SIZE
 #define RIONET_RX_RING_SIZE	CONFIG_RIONET_RX_SIZE
 #define RIONET_MAX_NETS		8
+#define RIONET_MSG_SIZE         RIO_MAX_MSG_SIZE
+#define RIONET_MAX_MTU          (RIONET_MSG_SIZE - ETH_HLEN)
 
 struct rionet_private {
 	struct rio_mport *mport;
@@ -443,6 +445,17 @@ static void rionet_set_msglevel(struct net_device *ndev, u32 value)
 	rnet->msg_enable = value;
 }
 
+static int rionet_change_mtu(struct net_device *ndev, int new_mtu)
+{
+	if ((new_mtu < 68) || (new_mtu > RIONET_MAX_MTU)) {
+		printk(KERN_ERR "%s: Invalid MTU size %d\n",
+		       ndev->name, new_mtu);
+		return -EINVAL;
+	}
+	ndev->mtu = new_mtu;
+	return 0;
+}
+
 static const struct ethtool_ops rionet_ethtool_ops = {
 	.get_drvinfo = rionet_get_drvinfo,
 	.get_msglevel = rionet_get_msglevel,
@@ -454,7 +467,7 @@ static const struct net_device_ops rionet_netdev_ops = {
 	.ndo_open		= rionet_open,
 	.ndo_stop		= rionet_close,
 	.ndo_start_xmit		= rionet_start_xmit,
-	.ndo_change_mtu		= eth_change_mtu,
+	.ndo_change_mtu		= rionet_change_mtu,
 	.ndo_validate_addr	= eth_validate_addr,
 	.ndo_set_mac_address	= eth_mac_addr,
 };
@@ -489,7 +502,7 @@ static int rionet_setup_netdev(struct rio_mport *mport, struct net_device *ndev)
 	ndev->dev_addr[5] = device_id & 0xff;
 
 	ndev->netdev_ops = &rionet_netdev_ops;
-	ndev->mtu = RIO_MAX_MSG_SIZE - 14;
+	ndev->mtu = RIONET_MAX_MTU;
 	ndev->features = NETIF_F_LLTX;
 	SET_NETDEV_DEV(ndev, &mport->dev);
 	ndev->ethtool_ops = &rionet_ethtool_ops;