can: mcp251xfd: ethtool: add support

This patch adds basic ethtool support (to query the current and
maximum ring parameters) to the driver.

Link: https://lore.kernel.org/20220313083640.501791-5-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/spi/mcp251xfd/Makefile

@@ -6,6 +6,7 @@ mcp251xfd-objs :=
 mcp251xfd-objs += mcp251xfd-chip-fifo.o
 mcp251xfd-objs += mcp251xfd-core.o
 mcp251xfd-objs += mcp251xfd-crc16.o
+mcp251xfd-objs += mcp251xfd-ethtool.o
 mcp251xfd-objs += mcp251xfd-ram.o
 mcp251xfd-objs += mcp251xfd-regmap.o
 mcp251xfd-objs += mcp251xfd-ring.o

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

@@ -1871,6 +1871,8 @@ static int mcp251xfd_register(struct mcp251xfd_priv *priv)
 	if (err)
 		goto out_chip_sleep;
 
+	mcp251xfd_ethtool_init(priv);
+
 	err = register_candev(ndev);
 	if (err)
 		goto out_chip_sleep;

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

+// SPDX-License-Identifier: GPL-2.0
+//
+// mcp251xfd - Microchip MCP251xFD Family CAN controller driver
+//
+// Copyright (c) 2021, 2022 Pengutronix,
+//               Marc Kleine-Budde <kernel@pengutronix.de>
+//
+
+#include <linux/ethtool.h>
+
+#include "mcp251xfd.h"
+
+static void
+mcp251xfd_ring_get_ringparam(struct net_device *ndev,
+			     struct ethtool_ringparam *ring,
+			     struct kernel_ethtool_ringparam *kernel_ring,
+			     struct netlink_ext_ack *extack)
+{
+	const struct mcp251xfd_priv *priv = netdev_priv(ndev);
+
+	ring->rx_max_pending = MCP251XFD_RX_OBJ_NUM_MAX;
+	ring->tx_max_pending = MCP251XFD_TX_OBJ_NUM_MAX;
+
+	ring->rx_pending = priv->rx_obj_num;
+	ring->tx_pending = priv->tx->obj_num;
+}
+
+static const struct ethtool_ops mcp251xfd_ethtool_ops = {
+	.get_ringparam = mcp251xfd_ring_get_ringparam,
+};
+
+void mcp251xfd_ethtool_init(struct mcp251xfd_priv *priv)
+{
+	priv->ndev->ethtool_ops = &mcp251xfd_ethtool_ops;
+}

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

@@ -304,6 +304,8 @@ int mcp251xfd_ring_alloc(struct mcp251xfd_priv *priv)
 		rx_obj_size = sizeof(struct mcp251xfd_hw_rx_obj_can);
 	}
 
+	priv->rx_obj_num = 0;
+
 	tx_ring = priv->tx;
 	tx_ring->obj_num = tx_obj_num;
 	tx_ring->obj_size = tx_obj_size;
@@ -320,6 +322,8 @@ int mcp251xfd_ring_alloc(struct mcp251xfd_priv *priv)
 		rx_obj_num = min(1 << (fls(rx_obj_num) - 1),
 				 MCP251XFD_RX_OBJ_NUM_MAX);
 
+		priv->rx_obj_num += rx_obj_num;
+
 		rx_ring = kzalloc(sizeof(*rx_ring) + rx_obj_size * rx_obj_num,
 				  GFP_KERNEL);
 		if (!rx_ring) {

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

@@ -610,6 +610,7 @@ struct mcp251xfd_priv {
 	struct mcp251xfd_tx_ring tx[MCP251XFD_FIFO_TX_NUM];
 
 	u8 rx_ring_num;
+	u8 rx_obj_num;
 
 	struct mcp251xfd_ecc ecc;
 	struct mcp251xfd_regs_status regs_status;
@@ -891,6 +892,7 @@ int mcp251xfd_chip_fifo_init(const struct mcp251xfd_priv *priv);
 u16 mcp251xfd_crc16_compute2(const void *cmd, size_t cmd_size,
 			     const void *data, size_t data_size);
 u16 mcp251xfd_crc16_compute(const void *data, size_t data_size);
+void mcp251xfd_ethtool_init(struct mcp251xfd_priv *priv);
 int mcp251xfd_regmap_init(struct mcp251xfd_priv *priv);
 int mcp251xfd_ring_init(struct mcp251xfd_priv *priv);
 void mcp251xfd_ring_free(struct mcp251xfd_priv *priv);