can: slcan: add ethtool support to reset adapter errors

This patch adds a private flag to the slcan driver to switch the
"err-rst-on-open" setting on and off.

"err-rst-on-open" on  - Reset error states on opening command

"err-rst-on-open" off - Don't reset error states on opening command
                        (default)

The setting can only be changed if the interface is down:

    ip link set dev can0 down
    ethtool --set-priv-flags can0 err-rst-on-open {off|on}
    ip link set dev can0 up

Link: https://lore.kernel.org/all/20220628163137.413025-11-dario.binacchi@amarulasolutions.com
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 65 insertions, 0 deletions

diff --git a/drivers/net/can/slcan/slcan-ethtool.c b/drivers/net/can/slcan/slcan-ethtool.c
new file mode 100644
index 000000000000..bf0afdc4e49d
--- /dev/null
+++ b/drivers/net/can/slcan/slcan-ethtool.c
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0+
+/* Copyright (c) 2022 Amarula Solutions, Dario Binacchi <dario.binacchi@amarulasolutions.com>
+ *
+ */
+
+#include <linux/can/dev.h>
+#include <linux/ethtool.h>
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/platform_device.h>
+
+#include "slcan.h"
+
+static const char slcan_priv_flags_strings[][ETH_GSTRING_LEN] = {
+#define SLCAN_PRIV_FLAGS_ERR_RST_ON_OPEN BIT(0)
+	"err-rst-on-open",
+};
+
+static void slcan_get_strings(struct net_device *ndev, u32 stringset, u8 *data)
+{
+	switch (stringset) {
+	case ETH_SS_PRIV_FLAGS:
+		memcpy(data, slcan_priv_flags_strings,
+		       sizeof(slcan_priv_flags_strings));
+	}
+}
+
+static u32 slcan_get_priv_flags(struct net_device *ndev)
+{
+	u32 flags = 0;
+
+	if (slcan_err_rst_on_open(ndev))
+		flags |= SLCAN_PRIV_FLAGS_ERR_RST_ON_OPEN;
+
+	return flags;
+}
+
+static int slcan_set_priv_flags(struct net_device *ndev, u32 flags)
+{
+	bool err_rst_op_open = !!(flags & SLCAN_PRIV_FLAGS_ERR_RST_ON_OPEN);
+
+	return slcan_enable_err_rst_on_open(ndev, err_rst_op_open);
+}
+
+static int slcan_get_sset_count(struct net_device *netdev, int sset)
+{
+	switch (sset) {
+	case ETH_SS_PRIV_FLAGS:
+		return ARRAY_SIZE(slcan_priv_flags_strings);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static const struct ethtool_ops slcan_ethtool_ops = {
+	.get_strings = slcan_get_strings,
+	.get_priv_flags = slcan_get_priv_flags,
+	.set_priv_flags = slcan_set_priv_flags,
+	.get_sset_count = slcan_get_sset_count,
+};
+
+void slcan_set_ethtool_ops(struct net_device *netdev)
+{
+	netdev->ethtool_ops = &slcan_ethtool_ops;
+}