can: rockchip_canfd: add stats support for errata workarounds

The driver contains workarounds for some of the rk3568v2 errata. Add
ethtool-based statistics ("ethtool -S") to track how often an erratum
workaround was needed.

Tested-by: Alibek Omarov <[e-mail]>
Acked-by: Heiko Stuebner <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Marc Kleine-Budde <[e-mail]>

drivers/net/can/rockchip/Makefile

···
 
 rockchip_canfd-objs :=
 rockchip_canfd-objs += rockchip_canfd-core.o
+rockchip_canfd-objs += rockchip_canfd-ethtool.o
 rockchip_canfd-objs += rockchip_canfd-rx.o
 rockchip_canfd-objs += rockchip_canfd-timestamp.o
 rockchip_canfd-objs += rockchip_canfd-tx.o

drivers/net/can/rockchip/rockchip_canfd-core.c

···
 	if (err)
 		goto out_pm_runtime_disable;
 
+	rkcanfd_ethtool_init(priv);
+
 	err = register_candev(ndev);
 	if (err)
 		goto out_pm_runtime_put_sync;

drivers/net/can/rockchip/rockchip_canfd-ethtool.c

···
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (c) 2023, 2024 Pengutronix,
+//               Marc Kleine-Budde <[e-mail]>
+//
+
+#include <linux/ethtool.h>
+
+#include "rockchip_canfd.h"
+
+enum rkcanfd_stats_type {
+	RKCANFD_STATS_TYPE_RX_FIFO_EMPTY_ERRORS,
+	RKCANFD_STATS_TYPE_TX_EXTENDED_AS_STANDARD_ERRORS,
+};
+
+static const char rkcanfd_stats_strings[][ETH_GSTRING_LEN] = {
+	[RKCANFD_STATS_TYPE_RX_FIFO_EMPTY_ERRORS] = "rx_fifo_empty_errors",
+	[RKCANFD_STATS_TYPE_TX_EXTENDED_AS_STANDARD_ERRORS] = "tx_extended_as_standard_errors",
+};
+
+static void
+rkcanfd_ethtool_get_strings(struct net_device *ndev, u32 stringset, u8 *buf)
+{
+	switch (stringset) {
+	case ETH_SS_STATS:
+		memcpy(buf, rkcanfd_stats_strings,
+		       sizeof(rkcanfd_stats_strings));
+	}
+}
+
+static int rkcanfd_ethtool_get_sset_count(struct net_device *netdev, int sset)
+{
+	switch (sset) {
+	case ETH_SS_STATS:
+		return ARRAY_SIZE(rkcanfd_stats_strings);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static void
+rkcanfd_ethtool_get_ethtool_stats(struct net_device *ndev,
+				  struct ethtool_stats *stats, u64 *data)
+{
+	struct rkcanfd_priv *priv = netdev_priv(ndev);
+	struct rkcanfd_stats *rkcanfd_stats;
+	unsigned int start;
+
+	rkcanfd_stats = &priv->stats;
+
+	do {
+		start = u64_stats_fetch_begin(&rkcanfd_stats->syncp);
+
+		data[RKCANFD_STATS_TYPE_RX_FIFO_EMPTY_ERRORS] =
+			u64_stats_read(&rkcanfd_stats->rx_fifo_empty_errors);
+		data[RKCANFD_STATS_TYPE_TX_EXTENDED_AS_STANDARD_ERRORS] =
+			u64_stats_read(&rkcanfd_stats->tx_extended_as_standard_errors);
+	} while (u64_stats_fetch_retry(&rkcanfd_stats->syncp, start));
+}
+
+static const struct ethtool_ops rkcanfd_ethtool_ops = {
+	.get_ts_info = ethtool_op_get_ts_info,
+	.get_strings = rkcanfd_ethtool_get_strings,
+	.get_sset_count = rkcanfd_ethtool_get_sset_count,
+	.get_ethtool_stats = rkcanfd_ethtool_get_ethtool_stats,
+};
+
+void rkcanfd_ethtool_init(struct rkcanfd_priv *priv)
+{
+	priv->ndev->ethtool_ops = &rkcanfd_ethtool_ops;
+
+	u64_stats_init(&priv->stats.syncp);
+}

drivers/net/can/rockchip/rockchip_canfd-rx.c

···
 				bool *tx_done)
 {
 	struct net_device_stats *stats = &priv->ndev->stats;
+	struct rkcanfd_stats *rkcanfd_stats = &priv->stats;
 	const struct canfd_frame *cfd_nominal;
 	const struct sk_buff *skb;
 	unsigned int tx_tail;
···
 		return 0;
 
 	/* Affected by Erratum 6 */
+	u64_stats_update_begin(&rkcanfd_stats->syncp);
+	u64_stats_inc(&rkcanfd_stats->tx_extended_as_standard_errors);
+	u64_stats_update_end(&rkcanfd_stats->syncp);
 
 	/* Manual handling of CAN Bus Error counters. See
 	 * rkcanfd_get_corrected_berr_counter() for detailed
···
 			 cfd->data, sizeof(cfd->data));
 
 	/* Erratum 5: Counters for TXEFIFO and RXFIFO may be wrong */
-	if (rkcanfd_fifo_header_empty(header))
+	if (rkcanfd_fifo_header_empty(header)) {
+		struct rkcanfd_stats *rkcanfd_stats = &priv->stats;
+
+		u64_stats_update_begin(&rkcanfd_stats->syncp);
+		u64_stats_inc(&rkcanfd_stats->rx_fifo_empty_errors);
+		u64_stats_update_end(&rkcanfd_stats->syncp);
+
 		return 0;
+	}
 
 	len = rkcanfd_fifo_header_to_cfd_header(priv, header, cfd);
 

drivers/net/can/rockchip/rockchip_canfd.h

···
 	u32 ts;
 };
 
+struct rkcanfd_stats {
+	struct u64_stats_sync syncp;
+
+	/* Erratum 5 */
+	u64_stats_t rx_fifo_empty_errors;
+
+	/* Erratum 6 */
+	u64_stats_t tx_extended_as_standard_errors;
+};
+
 struct rkcanfd_priv {
 	struct can_priv can;
 	struct can_rx_offload offload;
···
 	struct rkcanfd_devtype_data devtype_data;
 
 	struct can_berr_counter bec;
+
+	struct rkcanfd_stats stats;
 
 	struct reset_control *reset;
 	struct clk_bulk_data *clks;
···
 {
 	return RKCANFD_TXFIFO_DEPTH - rkcanfd_get_tx_pending(priv);
 }
+
+void rkcanfd_ethtool_init(struct rkcanfd_priv *priv);
 
 int rkcanfd_handle_rx_int(struct rkcanfd_priv *priv);