ethtool: Add support for low latency RS FEC

Add support for low latency Reed Solomon FEC as LLRS.

The LL-FEC is defined by the 25G/50G ethernet consortium,
in the document titled "Low Latency Reed Solomon Forward Error Correction"
Signed-off-by: NAya Levin <ayal@mellanox.com>
Reviewed-by: NEran Ben Elisha <eranbe@mellanox.com>
CC: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>

drivers/net/phy/phy-core.c

@@ -8,7 +8,7 @@
 
 const char *phy_speed_to_str(int speed)
 {
-	BUILD_BUG_ON_MSG(__ETHTOOL_LINK_MODE_MASK_NBITS != 74,
+	BUILD_BUG_ON_MSG(__ETHTOOL_LINK_MODE_MASK_NBITS != 75,
 		"Enum ethtool_link_mode_bit_indices and phylib are out of sync. "
 		"If a speed or mode has been added please update phy_speed_to_str "
 		"and the PHY settings array.\n");

include/uapi/linux/ethtool.h

@@ -1330,6 +1330,7 @@ enum ethtool_fec_config_bits {
 	ETHTOOL_FEC_OFF_BIT,
 	ETHTOOL_FEC_RS_BIT,
 	ETHTOOL_FEC_BASER_BIT,
+	ETHTOOL_FEC_LLRS_BIT,
 };
 
 #define ETHTOOL_FEC_NONE		(1 << ETHTOOL_FEC_NONE_BIT)
@@ -1337,6 +1338,7 @@ enum ethtool_fec_config_bits {
 #define ETHTOOL_FEC_OFF			(1 << ETHTOOL_FEC_OFF_BIT)
 #define ETHTOOL_FEC_RS			(1 << ETHTOOL_FEC_RS_BIT)
 #define ETHTOOL_FEC_BASER		(1 << ETHTOOL_FEC_BASER_BIT)
+#define ETHTOOL_FEC_LLRS		(1 << ETHTOOL_FEC_LLRS_BIT)
 
 /* CMDs currently supported */
 #define ETHTOOL_GSET		0x00000001 /* DEPRECATED, Get settings.
@@ -1521,7 +1523,7 @@ enum ethtool_link_mode_bit_indices {
 	ETHTOOL_LINK_MODE_400000baseLR8_ER8_FR8_Full_BIT = 71,
 	ETHTOOL_LINK_MODE_400000baseDR8_Full_BIT	 = 72,
 	ETHTOOL_LINK_MODE_400000baseCR8_Full_BIT	 = 73,
-
+	ETHTOOL_LINK_MODE_FEC_LLRS_BIT			 = 74,
 	/* must be last entry */
 	__ETHTOOL_LINK_MODE_MASK_NBITS
 };

net/ethtool/common.c

@@ -168,6 +168,7 @@ const char link_mode_names[][ETH_GSTRING_LEN] = {
 	__DEFINE_LINK_MODE_NAME(400000, LR8_ER8_FR8, Full),
 	__DEFINE_LINK_MODE_NAME(400000, DR8, Full),
 	__DEFINE_LINK_MODE_NAME(400000, CR8, Full),
+	__DEFINE_SPECIAL_MODE_NAME(FEC_LLRS, "LLRS"),
 };
 static_assert(ARRAY_SIZE(link_mode_names) == __ETHTOOL_LINK_MODE_MASK_NBITS);
 

net/ethtool/linkmodes.c

@@ -237,6 +237,7 @@ static const struct link_mode_info link_mode_params[] = {
 	__DEFINE_LINK_MODE_PARAMS(400000, LR8_ER8_FR8, Full),
 	__DEFINE_LINK_MODE_PARAMS(400000, DR8, Full),
 	__DEFINE_LINK_MODE_PARAMS(400000, CR8, Full),
+	__DEFINE_SPECIAL_MODE_PARAMS(FEC_LLRS),
 };
 
 static const struct nla_policy