net: mvpp2: add PPv23 RX FIFO flow control

New FIFO flow control feature was added in PPv23.
PPv2 FIFO polled by HW and trigger pause frame if FIFO
fill level is below threshold.
FIFO HW flow control enabled with CM3 RXQ&BM flow
control with ethtool.
Current  FIFO thresholds is:
9KB for port with maximum speed 10Gb/s port
4KB for port with maximum speed 5Gb/s port
2KB for port with maximum speed 1Gb/s port
Signed-off-by: Stefan Chulski <stefanc@marvell.com>
Acked-by: Marcin Wojtas <mw@semihalf.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/mvpp2/mvpp2.h

@@ -770,6 +770,18 @@
 #define MVPP2_TX_FIFO_THRESHOLD(kb)	\
 		((kb) * 1024 - MVPP2_TX_FIFO_THRESHOLD_MIN)
 
+/* RX FIFO threshold in 1KB granularity */
+#define MVPP23_PORT0_FIFO_TRSH	(9 * 1024)
+#define MVPP23_PORT1_FIFO_TRSH	(4 * 1024)
+#define MVPP23_PORT2_FIFO_TRSH	(2 * 1024)
+
+/* RX Flow Control Registers */
+#define MVPP2_RX_FC_REG(port)		(0x150 + 4 * (port))
+#define     MVPP2_RX_FC_EN		BIT(24)
+#define     MVPP2_RX_FC_TRSH_OFFS	16
+#define     MVPP2_RX_FC_TRSH_MASK	(0xFF << MVPP2_RX_FC_TRSH_OFFS)
+#define     MVPP2_RX_FC_TRSH_UNIT	256
+
 /* MSS Flow control */
 #define MSS_FC_COM_REG			0
 #define FLOW_CONTROL_ENABLE_BIT		BIT(0)
@@ -1498,6 +1510,8 @@ void mvpp2_dbgfs_init(struct mvpp2 *priv, const char *name);
 
 void mvpp2_dbgfs_cleanup(struct mvpp2 *priv);
 
+void mvpp23_rx_fifo_fc_en(struct mvpp2 *priv, int port, bool en);
+
 #ifdef CONFIG_MVPP2_PTP
 int mvpp22_tai_probe(struct device *dev, struct mvpp2 *priv);
 void mvpp22_tai_tstamp(struct mvpp2_tai *tai, u32 tstamp,
@@ -1530,4 +1544,5 @@ static inline bool mvpp22_rx_hwtstamping(struct mvpp2_port *port)
 {
 	return IS_ENABLED(CONFIG_MVPP2_PTP) && port->rx_hwtstamp;
 }
+
 #endif

drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c

@@ -6537,6 +6537,8 @@ static void mvpp2_mac_link_up(struct phylink_config *config,
 			mvpp2_bm_pool_update_fc(port, port->pool_long, tx_pause);
 			mvpp2_bm_pool_update_fc(port, port->pool_short, tx_pause);
 		}
+		if (port->priv->hw_version == MVPP23)
+			mvpp23_rx_fifo_fc_en(port->priv, port->id, tx_pause);
 	}
 
 	mvpp2_port_enable(port);
@@ -7005,6 +7007,55 @@ static void mvpp22_rx_fifo_init(struct mvpp2 *priv)
 	mvpp2_write(priv, MVPP2_RX_FIFO_INIT_REG, 0x1);
 }
 
+/* Configure Rx FIFO Flow control thresholds */
+static void mvpp23_rx_fifo_fc_set_tresh(struct mvpp2 *priv)
+{
+	int port, val;
+
+	/* Port 0: maximum speed -10Gb/s port
+	 *	   required by spec RX FIFO threshold 9KB
+	 * Port 1: maximum speed -5Gb/s port
+	 *	   required by spec RX FIFO threshold 4KB
+	 * Port 2: maximum speed -1Gb/s port
+	 *	   required by spec RX FIFO threshold 2KB
+	 */
+
+	/* Without loopback port */
+	for (port = 0; port < (MVPP2_MAX_PORTS - 1); port++) {
+		if (port == 0) {
+			val = (MVPP23_PORT0_FIFO_TRSH / MVPP2_RX_FC_TRSH_UNIT)
+				<< MVPP2_RX_FC_TRSH_OFFS;
+			val &= MVPP2_RX_FC_TRSH_MASK;
+			mvpp2_write(priv, MVPP2_RX_FC_REG(port), val);
+		} else if (port == 1) {
+			val = (MVPP23_PORT1_FIFO_TRSH / MVPP2_RX_FC_TRSH_UNIT)
+				<< MVPP2_RX_FC_TRSH_OFFS;
+			val &= MVPP2_RX_FC_TRSH_MASK;
+			mvpp2_write(priv, MVPP2_RX_FC_REG(port), val);
+		} else {
+			val = (MVPP23_PORT2_FIFO_TRSH / MVPP2_RX_FC_TRSH_UNIT)
+				<< MVPP2_RX_FC_TRSH_OFFS;
+			val &= MVPP2_RX_FC_TRSH_MASK;
+			mvpp2_write(priv, MVPP2_RX_FC_REG(port), val);
+		}
+	}
+}
+
+/* Configure Rx FIFO Flow control thresholds */
+void mvpp23_rx_fifo_fc_en(struct mvpp2 *priv, int port, bool en)
+{
+	int val;
+
+	val = mvpp2_read(priv, MVPP2_RX_FC_REG(port));
+
+	if (en)
+		val |= MVPP2_RX_FC_EN;
+	else
+		val &= ~MVPP2_RX_FC_EN;
+
+	mvpp2_write(priv, MVPP2_RX_FC_REG(port), val);
+}
+
 static void mvpp22_tx_fifo_set_hw(struct mvpp2 *priv, int port, int size)
 {
 	int threshold = MVPP2_TX_FIFO_THRESHOLD(size);
@@ -7156,6 +7207,8 @@ static int mvpp2_init(struct platform_device *pdev, struct mvpp2 *priv)
 	} else {
 		mvpp22_rx_fifo_init(priv);
 		mvpp22_tx_fifo_init(priv);
+		if (priv->hw_version == MVPP23)
+			mvpp23_rx_fifo_fc_set_tresh(priv);
 	}
 
 	if (priv->hw_version == MVPP21)