[RFC PATCH v1 0/1] add the netlink interface for CAN-FD Transmitter Delay Compensation (TDC)

@@ -5,6 +5,7 @@ can-dev-y			+= bittiming.o
 can-dev-y			+= dev.o
 can-dev-y			+= length.o
 can-dev-y			+= netlink.o
+can-dev-y			+= netlink-tdc.o
 can-dev-y			+= rx-offload.o
 can-dev-y                       += skb.o
 

@@ -0,0 +1,122 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021 Vincent Mailhol <mailhol.vincent@wanadoo.fr>
+ */
+
+#include <linux/can/dev.h>
+
+#include "netlink-tdc.h"
+
+static const struct nla_policy can_tdc_policy[IFLA_CAN_TDC_MAX + 1] = {
+	[IFLA_CAN_TDC_TDCV_MAX] = { .type = NLA_U32 },
+	[IFLA_CAN_TDC_TDCO_MAX] = { .type = NLA_U32 },
+	[IFLA_CAN_TDC_TDCF_MAX] = { .type = NLA_U32 },
+	[IFLA_CAN_TDC_TDCV] = { .type = NLA_U32 },
+	[IFLA_CAN_TDC_TDCO] = { .type = NLA_U32 },
+	[IFLA_CAN_TDC_TDCF] = { .type = NLA_U32 },
+};
+
+size_t can_tdc_get_size(const struct net_device *dev)
+{
+	struct can_priv *priv = netdev_priv(dev);
+	size_t size = nla_total_size(0) /* IFLA_CAN_TDC */;
+
+	if (priv->tdc_const) {
+		size += nla_total_size(sizeof(u32));	/* IFLA_CAN_TDCV_MAX */
+		size += nla_total_size(sizeof(u32));	/* IFLA_CAN_TDCO_MAX */
+		size += nla_total_size(sizeof(u32));	/* IFLA_CAN_TDCF_MAX */
+	}
+	if (priv->tdc.tdco) {
+		size += nla_total_size(sizeof(u32));	/* IFLA_CAN_TDCV */
+		size += nla_total_size(sizeof(u32));	/* IFLA_CAN_TDCO */
+		size += nla_total_size(sizeof(u32));	/* IFLA_CAN_TDCF */
+	}
+
+	return size;
+}
+
+int can_tdc_changelink(struct net_device *dev, const struct nlattr *nla,
+		       struct netlink_ext_ack *extack)
+{
+	struct nlattr *tb[IFLA_CAN_TDC_MAX + 1];
+	struct can_priv *priv = netdev_priv(dev);
+	struct can_tdc *tdc = &priv->tdc;
+	const struct can_tdc_const *tdc_const = priv->tdc_const;
+	int err;
+
+	if (!tdc_const)
+		return -EOPNOTSUPP;
+
+	if (dev->flags & IFF_UP)
+		return -EBUSY;
+
+	err = nla_parse_nested(tb, IFLA_CAN_TDC_MAX, nla,
+			       can_tdc_policy, extack);
+	if (err)
+		return err;
+
+	if (tb[IFLA_CAN_TDC_TDCV]) {
+		u32 tdcv = nla_get_u32(tb[IFLA_CAN_TDC_TDCV]);
+
+		if (tdcv && !tdc_const->tdcv_max)
+			return -EOPNOTSUPP;
+
+		if (tdcv > tdc_const->tdcv_max)
+			return -EINVAL;
+
+		tdc->tdcv = tdcv;
+	}
+
+	if (tb[IFLA_CAN_TDC_TDCO]) {
+		u32 tdco = nla_get_u32(tb[IFLA_CAN_TDC_TDCO]);
+
+		if (tdco && !tdc_const->tdco_max)
+			return -EOPNOTSUPP;
+
+		if (tdco > tdc_const->tdco_max)
+			return -EINVAL;
+
+		tdc->tdco = tdco;
+	}
+
+	if (tb[IFLA_CAN_TDC_TDCF]) {
+		u32 tdcf = nla_get_u32(tb[IFLA_CAN_TDC_TDCF]);
+
+		if (tdcf && !tdc_const->tdcf_max)
+			return -EOPNOTSUPP;
+
+		if (tdcf > tdc_const->tdcf_max)
+			return -EINVAL;
+
+		tdc->tdcf = tdcf;
+	}
+
+	return 0;
+}
+
+int can_tdc_fill_info(struct sk_buff *skb, const struct net_device *dev)
+{
+	struct nlattr *nest;
+	struct can_priv *priv = netdev_priv(dev);
+	struct can_tdc *tdc = &priv->tdc;
+	const struct can_tdc_const *tdc_const = priv->tdc_const;
+
+	if (!tdc_const)
+		return 0;
+
+	nest = nla_nest_start(skb, IFLA_CAN_TDC);
+	if (!nest)
+		return -EMSGSIZE;
+
+	if (nla_put_u32(skb, IFLA_CAN_TDC_TDCV_MAX, tdc_const->tdcv_max) ||
+	    nla_put_u32(skb, IFLA_CAN_TDC_TDCO_MAX, tdc_const->tdco_max) ||
+	    nla_put_u32(skb, IFLA_CAN_TDC_TDCF_MAX, tdc_const->tdcf_max) ||
+	    nla_put_u32(skb, IFLA_CAN_TDC_TDCV, tdc->tdcv) ||
+	    nla_put_u32(skb, IFLA_CAN_TDC_TDCO, tdc->tdco) ||
+	    nla_put_u32(skb, IFLA_CAN_TDC_TDCF, tdc->tdcf))
+		return -EMSGSIZE;
+
+	nla_nest_end(skb, nest);
+
+	return 0;
+}

@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2021 Vincent Mailhol <mailhol.vincent@wanadoo.fr>
+ */
+
+#ifndef _CAN_NETLINK_TDC_H
+#define _CAN_NETLINK_TDC_H
+
+#include <net/netlink.h>
+
+size_t can_tdc_get_size(const struct net_device *dev);
+
+int can_tdc_changelink(struct net_device *dev, const struct nlattr *nla,
+		       struct netlink_ext_ack *extack);
+
+int can_tdc_fill_info(struct sk_buff *skb, const struct net_device *dev);
+
+#endif /* !_CAN_NETLINK_TDC_H */

@@ -6,6 +6,7 @@
 
 #include <linux/can/dev.h>
 #include <net/rtnetlink.h>
+#include "netlink-tdc.h"
 
 static const struct nla_policy can_policy[IFLA_CAN_MAX + 1] = {
 	[IFLA_CAN_STATE] = { .type = NLA_U32 },

@@ -19,6 +20,7 @@ static const struct nla_policy can_policy[IFLA_CAN_MAX + 1] = {
 	[IFLA_CAN_DATA_BITTIMING] = { .len = sizeof(struct can_bittiming) },
 	[IFLA_CAN_DATA_BITTIMING_CONST]	= { .len = sizeof(struct can_bittiming_const) },
 	[IFLA_CAN_TERMINATION] = { .type = NLA_U16 },
+	[IFLA_CAN_TDC] = { .type = NLA_NESTED },
 };
 
 static int can_validate(struct nlattr *tb[], struct nlattr *data[],

@@ -46,7 +48,7 @@ static int can_validate(struct nlattr *tb[], struct nlattr *data[],
 			return -EOPNOTSUPP;
 	}
 
-	if (data[IFLA_CAN_DATA_BITTIMING]) {
+	if (data[IFLA_CAN_DATA_BITTIMING] || data[IFLA_CAN_TDC]) {
 		if (!is_can_fd || !data[IFLA_CAN_BITTIMING])
 			return -EOPNOTSUPP;
 	}

@@ -220,6 +222,12 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 		priv->termination = termval;
 	}
 
+	if (data[IFLA_CAN_TDC]) {
+		err = can_tdc_changelink(dev, data[IFLA_CAN_TDC], extack);
+		if (err)
+			return err;
+	}
+
 	return 0;
 }
 

@@ -254,6 +262,7 @@ static size_t can_get_size(const struct net_device *dev)
 		size += nla_total_size(sizeof(*priv->data_bitrate_const) *
 				       priv->data_bitrate_const_cnt);
 	size += sizeof(priv->bitrate_max);			/* IFLA_CAN_BITRATE_MAX */
+	size += can_tdc_get_size(dev);
 
 	return size;
 }

@@ -315,7 +324,9 @@ static int can_fill_info(struct sk_buff *skb, const struct net_device *dev)
 
 	    (nla_put(skb, IFLA_CAN_BITRATE_MAX,
 		     sizeof(priv->bitrate_max),
-		     &priv->bitrate_max))
+		     &priv->bitrate_max)) ||
+
+	    (can_tdc_fill_info(skb, dev))
 	    )
 
 		return -EMSGSIZE;

@@ -134,12 +134,34 @@ enum {
 	IFLA_CAN_BITRATE_CONST,
 	IFLA_CAN_DATA_BITRATE_CONST,
 	IFLA_CAN_BITRATE_MAX,
-	__IFLA_CAN_MAX
-};
+	IFLA_CAN_TDC,
 
-#define IFLA_CAN_MAX	(__IFLA_CAN_MAX - 1)
+	/* add new constants above here */
+	__IFLA_CAN_MAX,
+	IFLA_CAN_MAX = __IFLA_CAN_MAX - 1
+};
 
 /* u16 termination range: 1..65535 Ohms */
 #define CAN_TERMINATION_DISABLED 0
 
+/*
+ * CAN FD Transmitter Delay Compensation (TDC)
+ *
+ * Please refer to struct can_tdc_const and can_tdc in
+ * include/linux/can/bittiming.h for further details.
+ */
+enum {
+	IFLA_CAN_TDC_UNSPEC,
+	IFLA_CAN_TDC_TDCV_MAX,	/* u32 */
+	IFLA_CAN_TDC_TDCO_MAX,	/* u32 */
+	IFLA_CAN_TDC_TDCF_MAX,	/* u32 */
+	IFLA_CAN_TDC_TDCV,	/* u32 */
+	IFLA_CAN_TDC_TDCO,	/* u32 */
+	IFLA_CAN_TDC_TDCF,	/* u32 */
+
+	/* add new constants above here */
+	__IFLA_CAN_TDC,
+	IFLA_CAN_TDC_MAX = __IFLA_CAN_TDC - 1
+};
+
 #endif /* !_UAPI_CAN_NETLINK_H */