net: marvell: prestera: Add ethtool interface support

The ethtool API provides support for the configuration of the following
features: speed and duplex, auto-negotiation, MDI-x, forward error
correction, port media type. The API also provides information about the
port status, hardware and software statistic. The following limitation
exists:

    - port media type should be configured before speed setting
    - ethtool -m option is not supported
    - ethtool -p option is not supported
    - ethtool -r option is supported for RJ45 port only
    - the following combination of parameters is not supported:

          ethtool -s sw1pX port XX autoneg on

    - forward error correction feature is supported only on SFP ports, 10G
      speed

    - auto-negotiation and MDI-x features are not supported on
      Copper-to-Fiber SFP module

Co-developed-by: Andrii Savka <andrii.savka@plvision.eu>
Signed-off-by: Andrii Savka <andrii.savka@plvision.eu>
Co-developed-by: Serhiy Boiko <serhiy.boiko@plvision.eu>
Signed-off-by: Serhiy Boiko <serhiy.boiko@plvision.eu>
Signed-off-by: Vadym Kochan <vadym.kochan@plvision.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: vkochan-plv

drivers/net/ethernet/marvell/prestera/Makefile

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_PRESTERA)	+= prestera.o
 prestera-objs		:= prestera_main.o prestera_hw.o prestera_dsa.o \
-			   prestera_rxtx.o prestera_devlink.o
+			   prestera_rxtx.o prestera_devlink.o prestera_ethtool.o
 
 obj-$(CONFIG_PRESTERA_PCI)	+= prestera_pci.o

drivers/net/ethernet/marvell/prestera/prestera.h

@@ -169,4 +169,7 @@ void prestera_device_unregister(struct prestera_device *dev);
 struct prestera_port *prestera_port_find_by_hwid(struct prestera_switch *sw,
 						 u32 dev_id, u32 hw_id);
 
+int prestera_port_autoneg_set(struct prestera_port *port, bool enable,
+			      u64 adver_link_modes, u8 adver_fec);
+
 #endif /* _PRESTERA_H_ */