ravb: Initialize GbEthernet DMAC

Initialize GbEthernet DMAC found on RZ/G2L SoC.
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/ravb.h

@@ -81,6 +81,7 @@ enum ravb_reg {
 	RQC3	= 0x00A0,
 	RQC4	= 0x00A4,
 	RPC	= 0x00B0,
+	RTC	= 0x00B4,	/* R-Car Gen3 and RZ/G2L only */
 	UFCW	= 0x00BC,
 	UFCS	= 0x00C0,
 	UFCV0	= 0x00C4,
@@ -193,7 +194,7 @@ enum ravb_reg {
 	GECMR	= 0x05b0,
 	MAHR	= 0x05c0,
 	MALR	= 0x05c8,
-	TROCR	= 0x0700,	/* R-Car Gen3 only */
+	TROCR	= 0x0700,	/* R-Car Gen3 and RZ/G2L only */
 	CEFCR	= 0x0740,
 	FRECR	= 0x0748,
 	TSFRCR	= 0x0750,

drivers/net/ethernet/renesas/ravb_main.c

@@ -489,7 +489,35 @@ static void ravb_emac_init(struct net_device *ndev)
 
 static int ravb_dmac_init_gbeth(struct net_device *ndev)
 {
-	/* Place holder */
+	int error;
+
+	error = ravb_ring_init(ndev, RAVB_BE);
+	if (error)
+		return error;
+
+	/* Descriptor format */
+	ravb_ring_format(ndev, RAVB_BE);
+
+	/* Set AVB RX */
+	ravb_write(ndev, 0x60000000, RCR);
+
+	/* Set Max Frame Length (RTC) */
+	ravb_write(ndev, 0x7ffc0000 | GBETH_RX_BUFF_MAX, RTC);
+
+	/* Set FIFO size */
+	ravb_write(ndev, 0x00222200, TGC);
+
+	ravb_write(ndev, 0, TCCR);
+
+	/* Frame receive */
+	ravb_write(ndev, RIC0_FRE0, RIC0);
+	/* Disable FIFO full warning */
+	ravb_write(ndev, 0x0, RIC1);
+	/* Receive FIFO full error, descriptor empty */
+	ravb_write(ndev, RIC2_QFE0 | RIC2_RFFE, RIC2);
+
+	ravb_write(ndev, TIC_FTE0, TIC);
+
 	return 0;
 }