Reviewed-by: Suman Anna <redacted>
Signed-off-by: Franklin S Cooper Jr <redacted>
[nsekhar@ti.com: fix build error with !CONFIG_OF]
Signed-off-by: Sekhar Nori <redacted>
Signed-off-by: Faiz Abbas <redacted>
---
 drivers/net/can/dev.c            | 45 +++++++++++++++++++++++++++++++++++++++-
 include/linux/can/dev.h          |  8 +++++++
 include/uapi/linux/can/netlink.h |  1 +
 3 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index 365a8cc..c5bc33f 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c

@@ -27,6 +27,7 @@
 #include <linux/can/skb.h>
 #include <linux/can/netlink.h>
 #include <linux/can/led.h>
+#include <linux/of.h>
 #include <net/rtnetlink.h>
 
 #define MOD_DESC "CAN device driver interface"

@@ -814,6 +815,29 @@ int open_candev(struct net_device *dev)
 }
 EXPORT_SYMBOL_GPL(open_candev);
 
+#ifdef CONFIG_OF
+/* Common function that can be used to understand the limitation of
+ * a transceiver when it provides no means to determine these limitations
+ * at runtime.
+ */
+void of_can_transceiver(struct net_device *dev)
+{
+	struct device_node *dn;
+	struct can_priv *priv = netdev_priv(dev);
+	struct device_node *np = dev->dev.parent->of_node;
+	int ret;
+
+	dn = of_get_child_by_name(np, "can-transceiver");
+	if (!dn)
+		return;
+
+	ret = of_property_read_u32(dn, "max-bitrate", &priv->bitrate_max);
+	if ((ret && ret != -EINVAL) || (!ret && !priv->bitrate_max))
+		netdev_warn(dev, "Invalid value for transceiver max bitrate. Ignoring bitrate limit.\n");
+}
+EXPORT_SYMBOL_GPL(of_can_transceiver);
+#endif
+
 /*
  * Common close function for cleanup before the device gets closed.
  *

@@ -913,6 +937,13 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 					priv->bitrate_const_cnt);
 		if (err)
 			return err;
+
+		if (priv->bitrate_max && bt.bitrate > priv->bitrate_max) {
+			netdev_err(dev, "arbitration bitrate surpasses transceiver capabilities of %d bps\n",
+				   priv->bitrate_max);
+			return -EINVAL;
+		}
+
 		memcpy(&priv->bittiming, &bt, sizeof(bt));
 
 		if (priv->do_set_bittiming) {

@@ -997,6 +1028,13 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 					priv->data_bitrate_const_cnt);
 		if (err)
 			return err;
+
+		if (priv->bitrate_max && dbt.bitrate > priv->bitrate_max) {
+			netdev_err(dev, "canfd data bitrate surpasses transceiver capabilities of %d bps\n",
+				   priv->bitrate_max);
+			return -EINVAL;
+		}
+
 		memcpy(&priv->data_bittiming, &dbt, sizeof(dbt));
 
 		if (priv->do_set_data_bittiming) {

@@ -1064,6 +1102,7 @@ static size_t can_get_size(const struct net_device *dev)
 	if (priv->data_bitrate_const)				/* IFLA_CAN_DATA_BITRATE_CONST */
 		size += nla_total_size(sizeof(*priv->data_bitrate_const) *
 				       priv->data_bitrate_const_cnt);
+	size += sizeof(priv->bitrate_max);

 
 	return size;
 }

@@ -1121,7 +1160,11 @@ static int can_fill_info(struct sk_buff *skb, const struct net_device *dev)
 	     nla_put(skb, IFLA_CAN_DATA_BITRATE_CONST,
 		     sizeof(*priv->data_bitrate_const) *
 		     priv->data_bitrate_const_cnt,
-		     priv->data_bitrate_const))
+		     priv->data_bitrate_const)) ||
+
+	    (nla_put(skb, IFLA_CAN_BITRATE_MAX,
+		     sizeof(priv->bitrate_max),
+		     &priv->bitrate_max))
 	    )
 
 		return -EMSGSIZE;

diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index 61f1cf2..a199423 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h

@@ -46,8 +46,10 @@ struct can_priv {
 	unsigned int bitrate_const_cnt;
 	const u32 *data_bitrate_const;
 	unsigned int data_bitrate_const_cnt;
+	u32 bitrate_max;
 	struct can_clock clock;
 
+

 	enum can_state state;
 
 	/* CAN controller features - see include/uapi/linux/can/netlink.h */

@@ -166,6 +168,12 @@ void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
 unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx);
 void can_free_echo_skb(struct net_device *dev, unsigned int idx);
 
+#ifdef CONFIG_OF
+void of_can_transceiver(struct net_device *dev);
+#else
+static inline void of_can_transceiver(struct net_device *dev) { }
+#endif
+
 struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
 struct sk_buff *alloc_canfd_skb(struct net_device *dev,
 				struct canfd_frame **cfd);

diff --git a/include/uapi/linux/can/netlink.h b/include/uapi/linux/can/netlink.h
index 96710e7..9f56fad4 100644
--- a/include/uapi/linux/can/netlink.h
+++ b/include/uapi/linux/can/netlink.h

@@ -132,6 +132,7 @@ enum {
 	IFLA_CAN_TERMINATION_CONST,
 	IFLA_CAN_BITRATE_CONST,
 	IFLA_CAN_DATA_BITRATE_CONST,
+	IFLA_CAN_BITRATE_MAX,
 	__IFLA_CAN_MAX
 };