can: mcp251xfd: add RX IRQ coalescing ethtool support

This patch adds support ethtool based configuration for the RX IRQ
coalescing added in the previous patch.

Link: https://lore.kernel.org/20220313083640.501791-10-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/spi/mcp251xfd/mcp251xfd-ethtool.c

@@ -46,14 +46,69 @@ mcp251xfd_ring_set_ringparam(struct net_device *ndev,
 		return -EBUSY;
 
 	priv->rx_obj_num = layout.cur_rx;
+	priv->rx_obj_num_coalesce_irq = layout.rx_coalesce;
+	priv->tx->obj_num = layout.cur_tx;
+
+	return 0;
+}
+
+static int mcp251xfd_ring_get_coalesce(struct net_device *ndev,
+				       struct ethtool_coalesce *ec,
+				       struct kernel_ethtool_coalesce *kec,
+				       struct netlink_ext_ack *ext_ack)
+{
+	struct mcp251xfd_priv *priv = netdev_priv(ndev);
+	u32 rx_max_frames;
+
+	/* The ethtool doc says:
+	 * To disable coalescing, set usecs = 0 and max_frames = 1.
+	 */
+	if (priv->rx_obj_num_coalesce_irq == 0)
+		rx_max_frames = 1;
+	else
+		rx_max_frames = priv->rx_obj_num_coalesce_irq;
+
+	ec->rx_max_coalesced_frames_irq = rx_max_frames;
+	ec->rx_coalesce_usecs_irq = priv->rx_coalesce_usecs_irq;
+
+	return 0;
+}
+
+static int mcp251xfd_ring_set_coalesce(struct net_device *ndev,
+				       struct ethtool_coalesce *ec,
+				       struct kernel_ethtool_coalesce *kec,
+				       struct netlink_ext_ack *ext_ack)
+{
+	struct mcp251xfd_priv *priv = netdev_priv(ndev);
+	const bool fd_mode = mcp251xfd_is_fd_mode(priv);
+	const struct ethtool_ringparam ring = {
+		.rx_pending = priv->rx_obj_num,
+		.tx_pending = priv->tx->obj_num,
+	};
+	struct can_ram_layout layout;
+
+	can_ram_get_layout(&layout, &mcp251xfd_ram_config, &ring, ec, fd_mode);
+
+	if ((layout.rx_coalesce != priv->rx_obj_num_coalesce_irq ||
+	     ec->rx_coalesce_usecs_irq != priv->rx_coalesce_usecs_irq) &&
+	    netif_running(ndev))
+		return -EBUSY;
+
+	priv->rx_obj_num = layout.cur_rx;
+	priv->rx_obj_num_coalesce_irq = layout.rx_coalesce;
+	priv->rx_coalesce_usecs_irq = ec->rx_coalesce_usecs_irq;
 	priv->tx->obj_num = layout.cur_tx;
 
 	return 0;
 }
 
 static const struct ethtool_ops mcp251xfd_ethtool_ops = {
+	.supported_coalesce_params = ETHTOOL_COALESCE_RX_USECS_IRQ |
+		ETHTOOL_COALESCE_RX_MAX_FRAMES_IRQ,
 	.get_ringparam = mcp251xfd_ring_get_ringparam,
 	.set_ringparam = mcp251xfd_ring_set_ringparam,
+	.get_coalesce = mcp251xfd_ring_get_coalesce,
+	.set_coalesce = mcp251xfd_ring_set_coalesce,
 };
 
 void mcp251xfd_ethtool_init(struct mcp251xfd_priv *priv)

drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c

@@ -374,6 +374,7 @@ const struct can_ram_config mcp251xfd_ram_config = {
 		.def[CAN_RAM_MODE_CANFD] = CAN_RAM_NUM_MAX,
 		.fifo_num = MCP251XFD_FIFO_RX_NUM,
 		.fifo_depth_min = MCP251XFD_RX_FIFO_DEPTH_MIN,
+		.fifo_depth_coalesce_min = MCP251XFD_RX_FIFO_DEPTH_COALESCE_MIN,
 	},
 	.tx = {
 		.size[CAN_RAM_MODE_CAN] = sizeof(struct mcp251xfd_hw_tef_obj) +

drivers/net/can/spi/mcp251xfd/mcp251xfd.h

@@ -406,6 +406,7 @@ static_assert(MCP251XFD_TIMESTAMP_WORK_DELAY_SEC <
 #define MCP251XFD_RX_OBJ_NUM_MIN 16U
 #define MCP251XFD_RX_OBJ_NUM_MAX (MCP251XFD_FIFO_RX_NUM * MCP251XFD_FIFO_DEPTH)
 #define MCP251XFD_RX_FIFO_DEPTH_MIN 4U
+#define MCP251XFD_RX_FIFO_DEPTH_COALESCE_MIN 8U
 
 #define MCP251XFD_TX_OBJ_NUM_MIN 2U
 #define MCP251XFD_TX_OBJ_NUM_MAX 8U