net/mlx5e: Verify coalescing parameters in range

Add check of coalescing parameters received through ethtool are within
range of values supported by the HW.
Driver gets the coalescing rx/tx-usecs and rx/tx-frames as set by the
users through ethtool. The ethtool support up to 32 bit value for each.
However, mlx5 modify cq limits the coalescing time parameter to 12 bit
and coalescing frames parameters to 16 bits.
Return out of range error if user tries to set these parameters to
higher values.

Fixes: f62b8bb8 ('net/mlx5: Extend mlx5_core to support ConnectX-4 Ethernet functionality')
Signed-off-by: Moshe Shemesh <moshe@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c

@@ -477,6 +477,9 @@ static int mlx5e_get_coalesce(struct net_device *netdev,
 	return mlx5e_ethtool_get_coalesce(priv, coal);
 }
 
+#define MLX5E_MAX_COAL_TIME		MLX5_MAX_CQ_PERIOD
+#define MLX5E_MAX_COAL_FRAMES		MLX5_MAX_CQ_COUNT
+
 static void
 mlx5e_set_priv_channels_coalesce(struct mlx5e_priv *priv, struct ethtool_coalesce *coal)
 {
@@ -511,6 +514,20 @@ int mlx5e_ethtool_set_coalesce(struct mlx5e_priv *priv,
 	if (!MLX5_CAP_GEN(mdev, cq_moderation))
 		return -EOPNOTSUPP;
 
+	if (coal->tx_coalesce_usecs > MLX5E_MAX_COAL_TIME ||
+	    coal->rx_coalesce_usecs > MLX5E_MAX_COAL_TIME) {
+		netdev_info(priv->netdev, "%s: maximum coalesce time supported is %lu usecs\n",
+			    __func__, MLX5E_MAX_COAL_TIME);
+		return -ERANGE;
+	}
+
+	if (coal->tx_max_coalesced_frames > MLX5E_MAX_COAL_FRAMES ||
+	    coal->rx_max_coalesced_frames > MLX5E_MAX_COAL_FRAMES) {
+		netdev_info(priv->netdev, "%s: maximum coalesced frames supported is %lu\n",
+			    __func__, MLX5E_MAX_COAL_FRAMES);
+		return -ERANGE;
+	}
+
 	mutex_lock(&priv->state_lock);
 	new_channels.params = priv->channels.params;