can: xilinx_can: Fix missing Rx can packets on CANFD2.0

CANFD2.0 core uses BRAM for storing acceptance filter ID(AFID) and MASK
(AFMASK)registers. So by default AFID and AFMASK registers contain random
data. Due to random data, we are not able to receive all CAN ids.

Initializing AFID and AFMASK registers with Zero before enabling
acceptance filter to receive all packets irrespective of ID and Mask.

Fixes: 0db9071 ("can: xilinx: add can 2.0 support")
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Srinivas Neeli <srinivas.neeli@xilinx.com>
Reviewed-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v5.0
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/xilinx_can.c

@@ -60,6 +60,8 @@ enum xcan_reg {
 	XCAN_TXMSG_BASE_OFFSET	= 0x0100, /* TX Message Space */
 	XCAN_RXMSG_BASE_OFFSET	= 0x1100, /* RX Message Space */
 	XCAN_RXMSG_2_BASE_OFFSET	= 0x2100, /* RX Message Space */
+	XCAN_AFR_2_MASK_OFFSET	= 0x0A00, /* Acceptance Filter MASK */
+	XCAN_AFR_2_ID_OFFSET	= 0x0A04, /* Acceptance Filter ID */
 };
 
 #define XCAN_FRAME_ID_OFFSET(frame_base)	((frame_base) + 0x00)
@@ -1809,6 +1811,11 @@ static int xcan_probe(struct platform_device *pdev)
 
 	pm_runtime_put(&pdev->dev);
 
+	if (priv->devtype.flags & XCAN_FLAG_CANFD_2) {
+		priv->write_reg(priv, XCAN_AFR_2_ID_OFFSET, 0x00000000);
+		priv->write_reg(priv, XCAN_AFR_2_MASK_OFFSET, 0x00000000);
+	}
+
 	netdev_dbg(ndev, "reg_base=0x%p irq=%d clock=%d, tx buffers: actual %d, using %d\n",
 		   priv->reg_base, ndev->irq, priv->can.clock.freq,
 		   hw_tx_max, priv->tx_max);