net: systemport: Dynamically allocate number of TX rings

In preparation for adding SYSTEMPORT Lite, which has twice as less transmit
queues than SYSTEMPORT make sure we do allocate TX rings based on the
systemport,txq property to get an appropriate memory footprint.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c b/drivers/net/ethernet/broadcom/bcmsysport.c
index 744ed6d..31bb2c3 100644
--- a/drivers/net/ethernet/broadcom/bcmsysport.c
+++ b/drivers/net/ethernet/broadcom/bcmsysport.c
@@ -1752,6 +1752,10 @@
 	if (of_property_read_u32(dn, "systemport,num-rxq", &rxq))
 		rxq = 1;
 
+	/* Sanity check the number of transmit queues */
+	if (!txq || txq > TDMA_NUM_RINGS)
+		return -EINVAL;
+
 	dev = alloc_etherdev_mqs(sizeof(*priv), txq, rxq);
 	if (!dev)
 		return -ENOMEM;
@@ -1759,6 +1763,13 @@
 	/* Initialize private members */
 	priv = netdev_priv(dev);
 
+	/* Allocate number of TX rings */
+	priv->tx_rings = devm_kcalloc(&pdev->dev, txq,
+				      sizeof(struct bcm_sysport_tx_ring),
+				      GFP_KERNEL);
+	if (!priv->tx_rings)
+		return -ENOMEM;
+
 	priv->irq0 = platform_get_irq(pdev, 0);
 	priv->irq1 = platform_get_irq(pdev, 1);
 	priv->wol_irq = platform_get_irq(pdev, 2);
diff --git a/drivers/net/ethernet/broadcom/bcmsysport.h b/drivers/net/ethernet/broadcom/bcmsysport.h
index 1c82e3d..f051356 100644
--- a/drivers/net/ethernet/broadcom/bcmsysport.h
+++ b/drivers/net/ethernet/broadcom/bcmsysport.h
@@ -659,7 +659,7 @@
 	int			wol_irq;
 
 	/* Transmit rings */
-	struct bcm_sysport_tx_ring tx_rings[TDMA_NUM_RINGS];
+	struct bcm_sysport_tx_ring *tx_rings;
 
 	/* Receive queue */
 	void __iomem		*rx_bds;