sfc: Add support for MCDI v2

MCDI v2 adds a second header dword with wider command and length
fields.  It also defines extra error codes.

Change the fallback error number for unknown MCDI error codes from EIO
to EPROTO.  EIO is treated as indicating the MCDI transport has failed
and we need to reset the function, which is rather drastic.

v2 error codes and lengths don't fit into completion events, so for a
v2-capable transport, always read the response header rather then
using the event fields.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index 7283cc1..e1deec4 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -1029,6 +1029,7 @@
  * @timer_period_max: Maximum period of interrupt timer (in ticks)
  * @offload_features: net_device feature flags for protocol offload
  *	features implemented in hardware
+ * @mcdi_max_ver: Maximum MCDI version supported
  */
 struct efx_nic_type {
 	int (*probe)(struct efx_nic *efx);
@@ -1105,6 +1106,7 @@
 	unsigned int phys_addr_channels;
 	unsigned int timer_period_max;
 	netdev_features_t offload_features;
+	int mcdi_max_ver;
 };
 
 /**************************************************************************