mlxsw: core: Parse TLVs' offsets of incoming EMADs

Until now the code assumes a fixed structure which makes it difficult to
support EMADs with and without new TLVs.

Make it more generic by parsing the TLVs when the EMADs are received and
store the offset to the different TLVs in the control block. Using these
offsets to extract information from the EMADs without relying on a specific
structure.
Signed-off-by: Shalom Toledo <shalomt@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/core.c

@@ -361,20 +361,45 @@ static void mlxsw_emad_construct(struct sk_buff *skb,
 	mlxsw_emad_construct_eth_hdr(skb);
 }
 
+struct mlxsw_emad_tlv_offsets {
+	u16 op_tlv;
+	u16 reg_tlv;
+};
+
+static void mlxsw_emad_tlv_parse(struct sk_buff *skb)
+{
+	struct mlxsw_emad_tlv_offsets *offsets =
+		(struct mlxsw_emad_tlv_offsets *) skb->cb;
+
+	offsets->op_tlv = MLXSW_EMAD_ETH_HDR_LEN;
+	offsets->reg_tlv = MLXSW_EMAD_ETH_HDR_LEN +
+			   MLXSW_EMAD_OP_TLV_LEN * sizeof(u32);
+}
+
 static char *mlxsw_emad_op_tlv(const struct sk_buff *skb)
 {
-	return ((char *) (skb->data + MLXSW_EMAD_ETH_HDR_LEN));
+	struct mlxsw_emad_tlv_offsets *offsets =
+		(struct mlxsw_emad_tlv_offsets *) skb->cb;
+
+	return ((char *) (skb->data + offsets->op_tlv));
 }
 
 static char *mlxsw_emad_reg_tlv(const struct sk_buff *skb)
 {
-	return ((char *) (skb->data + MLXSW_EMAD_ETH_HDR_LEN +
-				      MLXSW_EMAD_OP_TLV_LEN * sizeof(u32)));
+	struct mlxsw_emad_tlv_offsets *offsets =
+		(struct mlxsw_emad_tlv_offsets *) skb->cb;
+
+	return ((char *) (skb->data + offsets->reg_tlv));
 }
 
-static char *mlxsw_emad_reg_payload(const char *op_tlv)
+static char *mlxsw_emad_reg_payload(const char *reg_tlv)
 {
-	return ((char *) (op_tlv + (MLXSW_EMAD_OP_TLV_LEN + 1) * sizeof(u32)));
+	return ((char *) (reg_tlv + sizeof(u32)));
+}
+
+static char *mlxsw_emad_reg_payload_cmd(const char *mbox)
+{
+	return ((char *) (mbox + (MLXSW_EMAD_OP_TLV_LEN + 1) * sizeof(u32)));
 }
 
 static u64 mlxsw_emad_get_tid(const struct sk_buff *skb)
@@ -535,11 +560,11 @@ static void mlxsw_emad_process_response(struct mlxsw_core *mlxsw_core,
 		mlxsw_emad_transmit_retry(mlxsw_core, trans);
 	} else {
 		if (err == 0) {
-			char *op_tlv = mlxsw_emad_op_tlv(skb);
+			char *reg_tlv = mlxsw_emad_reg_tlv(skb);
 
 			if (trans->cb)
 				trans->cb(mlxsw_core,
-					  mlxsw_emad_reg_payload(op_tlv),
+					  mlxsw_emad_reg_payload(reg_tlv),
 					  trans->reg->len, trans->cb_priv);
 		}
 		mlxsw_emad_trans_finish(trans, err);
@@ -556,6 +581,8 @@ static void mlxsw_emad_rx_listener_func(struct sk_buff *skb, u8 local_port,
 	trace_devlink_hwmsg(priv_to_devlink(mlxsw_core), true, 0,
 			    skb->data, skb->len);
 
+	mlxsw_emad_tlv_parse(skb);
+
 	if (!mlxsw_emad_is_resp(skb))
 		goto free_skb;
 
@@ -1395,12 +1422,16 @@ static void mlxsw_core_event_listener_func(struct sk_buff *skb, u8 local_port,
 	struct mlxsw_event_listener_item *event_listener_item = priv;
 	struct mlxsw_reg_info reg;
 	char *payload;
-	char *op_tlv = mlxsw_emad_op_tlv(skb);
-	char *reg_tlv = mlxsw_emad_reg_tlv(skb);
+	char *reg_tlv;
+	char *op_tlv;
+
+	mlxsw_emad_tlv_parse(skb);
+	op_tlv = mlxsw_emad_op_tlv(skb);
+	reg_tlv = mlxsw_emad_reg_tlv(skb);
 
 	reg.id = mlxsw_emad_op_tlv_register_id_get(op_tlv);
 	reg.len = (mlxsw_emad_reg_tlv_len_get(reg_tlv) - 1) * sizeof(u32);
-	payload = mlxsw_emad_reg_payload(op_tlv);
+	payload = mlxsw_emad_reg_payload(reg_tlv);
 	event_listener_item->el.func(&reg, payload, event_listener_item->priv);
 	dev_kfree_skb(skb);
 }
@@ -1713,7 +1744,7 @@ static int mlxsw_core_reg_access_cmd(struct mlxsw_core *mlxsw_core,
 	}
 
 	if (!err)
-		memcpy(payload, mlxsw_emad_reg_payload(out_mbox),
+		memcpy(payload, mlxsw_emad_reg_payload_cmd(out_mbox),
 		       reg->len);
 
 	mlxsw_cmd_mbox_free(out_mbox);