nfp: add helpers for FEC support

Implement helpers to determine and modify FEC modes via the NSP.
The NSP advertises FEC capabilities on a per port basis and provides
support for:
* Auto mode selection
* Reed Solomon
* BaseR
* None/Off
Signed-off-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.h

@@ -79,6 +79,18 @@ enum nfp_eth_aneg {
 	NFP_ANEG_DISABLED,
 };
 
+enum nfp_eth_fec {
+	NFP_FEC_AUTO_BIT = 0,
+	NFP_FEC_BASER_BIT,
+	NFP_FEC_REED_SOLOMON_BIT,
+	NFP_FEC_DISABLED_BIT,
+};
+
+#define NFP_FEC_AUTO		BIT(NFP_FEC_AUTO_BIT)
+#define NFP_FEC_BASER		BIT(NFP_FEC_BASER_BIT)
+#define NFP_FEC_REED_SOLOMON	BIT(NFP_FEC_REED_SOLOMON_BIT)
+#define NFP_FEC_DISABLED	BIT(NFP_FEC_DISABLED_BIT)
+
 /**
  * struct nfp_eth_table - ETH table information
  * @count:	number of table entries
@@ -93,6 +105,7 @@ enum nfp_eth_aneg {
  * @speed:	interface speed (in Mbps)
  * @interface:	interface (module) plugged in
  * @media:	media type of the @interface
+ * @fec:	forward error correction mode
  * @aneg:	auto negotiation mode
  * @mac_addr:	interface MAC address
  * @label_port:	port id
@@ -105,6 +118,7 @@ enum nfp_eth_aneg {
  * @port_type:	one of %PORT_* defines for ethtool
  * @port_lanes:	total number of lanes on the port (sum of lanes of all subports)
  * @is_split:	is interface part of a split port
+ * @fec_modes_supported:	bitmap of FEC modes supported
  */
 struct nfp_eth_table {
 	unsigned int count;
@@ -120,6 +134,7 @@ struct nfp_eth_table {
 		unsigned int interface;
 		enum nfp_eth_media media;
 
+		enum nfp_eth_fec fec;
 		enum nfp_eth_aneg aneg;
 
 		u8 mac_addr[ETH_ALEN];
@@ -139,6 +154,8 @@ struct nfp_eth_table {
 		unsigned int port_lanes;
 
 		bool is_split;
+
+		unsigned int fec_modes_supported;
 	} ports[0];
 };
 
@@ -149,6 +166,19 @@ __nfp_eth_read_ports(struct nfp_cpp *cpp, struct nfp_nsp *nsp);
 int nfp_eth_set_mod_enable(struct nfp_cpp *cpp, unsigned int idx, bool enable);
 int nfp_eth_set_configured(struct nfp_cpp *cpp, unsigned int idx,
 			   bool configed);
+int
+nfp_eth_set_fec(struct nfp_cpp *cpp, unsigned int idx, enum nfp_eth_fec mode);
+
+static inline bool nfp_eth_can_support_fec(struct nfp_eth_table_port *eth_port)
+{
+	return !!eth_port->fec_modes_supported;
+}
+
+static inline unsigned int
+nfp_eth_supported_fec_modes(struct nfp_eth_table_port *eth_port)
+{
+	return eth_port->fec_modes_supported;
+}
 
 struct nfp_nsp *nfp_eth_config_start(struct nfp_cpp *cpp, unsigned int idx);
 int nfp_eth_config_commit_end(struct nfp_nsp *nsp);

drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c

@@ -55,6 +55,8 @@
 #define NSP_ETH_PORT_INDEX		GENMASK_ULL(15, 8)
 #define NSP_ETH_PORT_LABEL		GENMASK_ULL(53, 48)
 #define NSP_ETH_PORT_PHYLABEL		GENMASK_ULL(59, 54)
+#define NSP_ETH_PORT_FEC_SUPP_BASER	BIT_ULL(60)
+#define NSP_ETH_PORT_FEC_SUPP_RS	BIT_ULL(61)
 
 #define NSP_ETH_PORT_LANES_MASK		cpu_to_le64(NSP_ETH_PORT_LANES)
 
@@ -67,6 +69,7 @@
 #define NSP_ETH_STATE_MEDIA		GENMASK_ULL(21, 20)
 #define NSP_ETH_STATE_OVRD_CHNG		BIT_ULL(22)
 #define NSP_ETH_STATE_ANEG		GENMASK_ULL(25, 23)
+#define NSP_ETH_STATE_FEC		GENMASK_ULL(27, 26)
 
 #define NSP_ETH_CTRL_CONFIGURED		BIT_ULL(0)
 #define NSP_ETH_CTRL_ENABLED		BIT_ULL(1)
@@ -75,6 +78,7 @@
 #define NSP_ETH_CTRL_SET_RATE		BIT_ULL(4)
 #define NSP_ETH_CTRL_SET_LANES		BIT_ULL(5)
 #define NSP_ETH_CTRL_SET_ANEG		BIT_ULL(6)
+#define NSP_ETH_CTRL_SET_FEC		BIT_ULL(7)
 
 enum nfp_eth_raw {
 	NSP_ETH_RAW_PORT = 0,
@@ -152,6 +156,7 @@ nfp_eth_port_translate(struct nfp_nsp *nsp, const union eth_table_entry *src,
 		       unsigned int index, struct nfp_eth_table_port *dst)
 {
 	unsigned int rate;
+	unsigned int fec;
 	u64 port, state;
 
 	port = le64_to_cpu(src->port);
@@ -183,6 +188,18 @@ nfp_eth_port_translate(struct nfp_nsp *nsp, const union eth_table_entry *src,
 
 	dst->override_changed = FIELD_GET(NSP_ETH_STATE_OVRD_CHNG, state);
 	dst->aneg = FIELD_GET(NSP_ETH_STATE_ANEG, state);
+
+	if (nfp_nsp_get_abi_ver_minor(nsp) < 22)
+		return;
+
+	fec = FIELD_GET(NSP_ETH_PORT_FEC_SUPP_BASER, port);
+	dst->fec_modes_supported |= fec << NFP_FEC_BASER_BIT;
+	fec = FIELD_GET(NSP_ETH_PORT_FEC_SUPP_RS, port);
+	dst->fec_modes_supported |= fec << NFP_FEC_REED_SOLOMON_BIT;
+	if (dst->fec_modes_supported)
+		dst->fec_modes_supported |= NFP_FEC_AUTO | NFP_FEC_DISABLED;
+
+	dst->fec = 1 << FIELD_GET(NSP_ETH_STATE_FEC, state);
 }
 
 static void
@@ -527,6 +544,53 @@ int __nfp_eth_set_aneg(struct nfp_nsp *nsp, enum nfp_eth_aneg mode)
 				      NSP_ETH_CTRL_SET_ANEG);
 }
 
+/**
+ * __nfp_eth_set_fec() - set PHY forward error correction control bit
+ * @nsp:	NFP NSP handle returned from nfp_eth_config_start()
+ * @mode:	Desired fec mode
+ *
+ * Set the PHY module forward error correction mode.
+ * Will write to hwinfo overrides in the flash (persistent config).
+ *
+ * Return: 0 or -ERRNO.
+ */
+static int __nfp_eth_set_fec(struct nfp_nsp *nsp, enum nfp_eth_fec mode)
+{
+	return NFP_ETH_SET_BIT_CONFIG(nsp, NSP_ETH_RAW_STATE,
+				      NSP_ETH_STATE_FEC, mode,
+				      NSP_ETH_CTRL_SET_FEC);
+}
+
+/**
+ * nfp_eth_set_fec() - set PHY forward error correction control mode
+ * @cpp:	NFP CPP handle
+ * @idx:	NFP chip-wide port index
+ * @mode:	Desired fec mode
+ *
+ * Return:
+ * 0 - configuration successful;
+ * 1 - no changes were needed;
+ * -ERRNO - configuration failed.
+ */
+int
+nfp_eth_set_fec(struct nfp_cpp *cpp, unsigned int idx, enum nfp_eth_fec mode)
+{
+	struct nfp_nsp *nsp;
+	int err;
+
+	nsp = nfp_eth_config_start(cpp, idx);
+	if (IS_ERR(nsp))
+		return PTR_ERR(nsp);
+
+	err = __nfp_eth_set_fec(nsp, mode);
+	if (err) {
+		nfp_eth_config_cleanup_end(nsp);
+		return err;
+	}
+
+	return nfp_eth_config_commit_end(nsp);
+}
+
 /**
  * __nfp_eth_set_speed() - set interface speed/rate
  * @nsp:	NFP NSP handle returned from nfp_eth_config_start()