This patch allows the CAN controller driver to define the number of echo
skb's used for the local loopback (echo), as suggested by Kurt Van
Dijck, with the function:

  struct net_device *alloc_candev(int sizeof_priv,
                                  unsigned int echo_skb_max);

The CAN drivers have been adapted accordingly. For the ems_usb driver,
as suggested by Sebastian Haas, the number of echo skb's has been
increased to 10, which improves the transmission performance a lot.
Signed-off-by: NWolfgang Grandegger <wg@grandegger.com>
Signed-off-by: NKurt Van Dijck <kurt.van.dijck@eia.be>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds the function can_free_echo_skb to the CAN
device interface to allow upcoming drivers to release echo
skb's in case of error.
Signed-off-by: NWolfgang Grandegger <wg@grandegger.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The CAN network device driver interface provides a generic interface to
setup, configure and monitor CAN network devices. It exports a set of
common data structures and functions, which all real CAN network device
drivers should use. Please have a look to the SJA1000 or MSCAN driver
to understand how to use them. The name of the module is can-dev.ko.

Furthermore, it adds a Netlink interface allowing to configure the CAN
device using the program "ip" from the iproute2 utility suite.

For further information please check "Documentation/networking/can.txt"
Signed-off-by: NWolfgang Grandegger <wg@grandegger.com>
Signed-off-by: NOliver Hartkopp <oliver.hartkopp@volkswagen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>