can: Kconfig: select CAN driver infrastructure by default

The CAN bus support enabled with CONFIG_CAN provides a socket-based
access to CAN interfaces. With the introduction of the latest CAN protocol
CAN XL additional configuration status information needs to be exposed to
the network layer than formerly provided by standard Linux network drivers.

This requires the CAN driver infrastructure to be selected by default.
As the CAN network layer can only operate on CAN interfaces anyway all
distributions and common default configs enable at least one CAN driver.

So selecting CONFIG_CAN_DEV when CONFIG_CAN is selected by the user has
no effect on established configurations but solves potential build issues
when CONFIG_CAN[_XXX]=y is set together with CANFIG_CAN_DEV=m

Fixes: 1a620a7 ("can: raw: instantly reject unsupported CAN frames")
Reported-by: Vincent Mailhol <mailhol@kernel.org>
Closes: https://lore.kernel.org/all/CAMZ6RqL_nGszwoLPXn1Li8op-ox4k3Hs6p=Hw6+w0W=DTtobPw@mail.gmail.com/
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511280531.YnWW2Rxc-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202511280842.djCQ0N0O-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202511282325.uVQFRTkA-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202511291520.guIE1QHj-lkp@intel.com/
Suggested-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://patch.msgid.link/20251129090500.17484-1-socketcan@hartkopp.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Author: hartkopp

include/linux/can/dev.h

@@ -111,7 +111,14 @@ struct net_device *alloc_candev_mqs(int sizeof_priv, unsigned int echo_skb_max,
 void free_candev(struct net_device *dev);
 
 /* a candev safe wrapper around netdev_priv */
+#if IS_ENABLED(CONFIG_CAN_NETLINK)
 struct can_priv *safe_candev_priv(struct net_device *dev);
+#else
+static inline struct can_priv *safe_candev_priv(struct net_device *dev)
+{
+	return NULL;
+}
+#endif
 
 int open_candev(struct net_device *dev);
 void close_candev(struct net_device *dev);

net/can/Kconfig

@@ -5,6 +5,7 @@
 
 menuconfig CAN
 	tristate "CAN bus subsystem support"
+	select CAN_DEV
 	help
 	  Controller Area Network (CAN) is a slow (up to 1Mbit/s) serial
 	  communications protocol. Development of the CAN bus started in