sh_eth: WARN_ON() access to unimplemented TSU register

Commit 3365711df024 ("sh_eth: WARN on access to a register not implemented
in a particular chip") added  WARN_ON() to sh_eth_{read|write}() but not
to sh_eth_tsu_{read|write}(). Now that we've routed almost all TSU register
accesses  (except TSU_ADR{H|L}<n> -- which are special) thru the latter
pair of accessors, it makes sense to check for the unimplemented TSU
registers as well...

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/sh_eth.c

@@ -442,12 +442,22 @@ static void sh_eth_modify(struct net_device *ndev, int enum_index, u32 clear,
 static void sh_eth_tsu_write(struct sh_eth_private *mdp, u32 data,
 			     int enum_index)
 {
-	iowrite32(data, mdp->tsu_addr + mdp->reg_offset[enum_index]);
+	u16 offset = mdp->reg_offset[enum_index];
+
+	if (WARN_ON(offset == SH_ETH_OFFSET_INVALID))
+		return;
+
+	iowrite32(data, mdp->tsu_addr + offset);
 }
 
 static u32 sh_eth_tsu_read(struct sh_eth_private *mdp, int enum_index)
 {
-	return ioread32(mdp->tsu_addr + mdp->reg_offset[enum_index]);
+	u16 offset = mdp->reg_offset[enum_index];
+
+	if (WARN_ON(offset == SH_ETH_OFFSET_INVALID))
+		return ~0U;
+
+	return ioread32(mdp->tsu_addr + offset);
 }
 
 static void sh_eth_select_mii(struct net_device *ndev)