Merge branch 'fix-the-arc-emac-driver'

Andy Yan says:

====================
Fix the arc emac driver

The arc emac driver was broken for a long time,
The first broken happens when a dma releated fix introduced in Linux 5.10.
The second broken happens when a emac device tree node restyle introduced
in Linux 6.1.

These two patches are try to make the arc emac work again.

Changes in v2:
- Add cover letter.
- Add fix tag.
- Add more detail explaination.
====================

Link: https://patch.msgid.link/20241104130147.440125-1-andyshrk@163.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/arc/emac_main.c

@@ -111,6 +111,7 @@ static void arc_emac_tx_clean(struct net_device *ndev)
 {
 	struct arc_emac_priv *priv = netdev_priv(ndev);
 	struct net_device_stats *stats = &ndev->stats;
+	struct device *dev = ndev->dev.parent;
 	unsigned int i;
 
 	for (i = 0; i < TX_BD_NUM; i++) {
@@ -140,7 +141,7 @@ static void arc_emac_tx_clean(struct net_device *ndev)
 			stats->tx_bytes += skb->len;
 		}
 
-		dma_unmap_single(&ndev->dev, dma_unmap_addr(tx_buff, addr),
+		dma_unmap_single(dev, dma_unmap_addr(tx_buff, addr),
 				 dma_unmap_len(tx_buff, len), DMA_TO_DEVICE);
 
 		/* return the sk_buff to system */
@@ -174,6 +175,7 @@ static void arc_emac_tx_clean(struct net_device *ndev)
 static int arc_emac_rx(struct net_device *ndev, int budget)
 {
 	struct arc_emac_priv *priv = netdev_priv(ndev);
+	struct device *dev = ndev->dev.parent;
 	unsigned int work_done;
 
 	for (work_done = 0; work_done < budget; work_done++) {
@@ -223,9 +225,9 @@ static int arc_emac_rx(struct net_device *ndev, int budget)
 			continue;
 		}
 
-		addr = dma_map_single(&ndev->dev, (void *)skb->data,
+		addr = dma_map_single(dev, (void *)skb->data,
 				      EMAC_BUFFER_SIZE, DMA_FROM_DEVICE);
-		if (dma_mapping_error(&ndev->dev, addr)) {
+		if (dma_mapping_error(dev, addr)) {
 			if (net_ratelimit())
 				netdev_err(ndev, "cannot map dma buffer\n");
 			dev_kfree_skb(skb);
@@ -237,7 +239,7 @@ static int arc_emac_rx(struct net_device *ndev, int budget)
 		}
 
 		/* unmap previosly mapped skb */
-		dma_unmap_single(&ndev->dev, dma_unmap_addr(rx_buff, addr),
+		dma_unmap_single(dev, dma_unmap_addr(rx_buff, addr),
 				 dma_unmap_len(rx_buff, len), DMA_FROM_DEVICE);
 
 		pktlen = info & LEN_MASK;
@@ -423,6 +425,7 @@ static int arc_emac_open(struct net_device *ndev)
 {
 	struct arc_emac_priv *priv = netdev_priv(ndev);
 	struct phy_device *phy_dev = ndev->phydev;
+	struct device *dev = ndev->dev.parent;
 	int i;
 
 	phy_dev->autoneg = AUTONEG_ENABLE;
@@ -445,9 +448,9 @@ static int arc_emac_open(struct net_device *ndev)
 		if (unlikely(!rx_buff->skb))
 			return -ENOMEM;
 
-		addr = dma_map_single(&ndev->dev, (void *)rx_buff->skb->data,
+		addr = dma_map_single(dev, (void *)rx_buff->skb->data,
 				      EMAC_BUFFER_SIZE, DMA_FROM_DEVICE);
-		if (dma_mapping_error(&ndev->dev, addr)) {
+		if (dma_mapping_error(dev, addr)) {
 			netdev_err(ndev, "cannot dma map\n");
 			dev_kfree_skb(rx_buff->skb);
 			return -ENOMEM;
@@ -548,6 +551,7 @@ static void arc_emac_set_rx_mode(struct net_device *ndev)
 static void arc_free_tx_queue(struct net_device *ndev)
 {
 	struct arc_emac_priv *priv = netdev_priv(ndev);
+	struct device *dev = ndev->dev.parent;
 	unsigned int i;
 
 	for (i = 0; i < TX_BD_NUM; i++) {
@@ -555,7 +559,7 @@ static void arc_free_tx_queue(struct net_device *ndev)
 		struct buffer_state *tx_buff = &priv->tx_buff[i];
 
 		if (tx_buff->skb) {
-			dma_unmap_single(&ndev->dev,
+			dma_unmap_single(dev,
 					 dma_unmap_addr(tx_buff, addr),
 					 dma_unmap_len(tx_buff, len),
 					 DMA_TO_DEVICE);
@@ -579,6 +583,7 @@ static void arc_free_tx_queue(struct net_device *ndev)
 static void arc_free_rx_queue(struct net_device *ndev)
 {
 	struct arc_emac_priv *priv = netdev_priv(ndev);
+	struct device *dev = ndev->dev.parent;
 	unsigned int i;
 
 	for (i = 0; i < RX_BD_NUM; i++) {
@@ -586,7 +591,7 @@ static void arc_free_rx_queue(struct net_device *ndev)
 		struct buffer_state *rx_buff = &priv->rx_buff[i];
 
 		if (rx_buff->skb) {
-			dma_unmap_single(&ndev->dev,
+			dma_unmap_single(dev,
 					 dma_unmap_addr(rx_buff, addr),
 					 dma_unmap_len(rx_buff, len),
 					 DMA_FROM_DEVICE);
@@ -679,6 +684,7 @@ static netdev_tx_t arc_emac_tx(struct sk_buff *skb, struct net_device *ndev)
 	unsigned int len, *txbd_curr = &priv->txbd_curr;
 	struct net_device_stats *stats = &ndev->stats;
 	__le32 *info = &priv->txbd[*txbd_curr].info;
+	struct device *dev = ndev->dev.parent;
 	dma_addr_t addr;
 
 	if (skb_padto(skb, ETH_ZLEN))
@@ -692,10 +698,9 @@ static netdev_tx_t arc_emac_tx(struct sk_buff *skb, struct net_device *ndev)
 		return NETDEV_TX_BUSY;
 	}
 
-	addr = dma_map_single(&ndev->dev, (void *)skb->data, len,
-			      DMA_TO_DEVICE);
+	addr = dma_map_single(dev, (void *)skb->data, len, DMA_TO_DEVICE);
 
-	if (unlikely(dma_mapping_error(&ndev->dev, addr))) {
+	if (unlikely(dma_mapping_error(dev, addr))) {
 		stats->tx_dropped++;
 		stats->tx_errors++;
 		dev_kfree_skb_any(skb);

drivers/net/ethernet/arc/emac_mdio.c

@@ -133,6 +133,7 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
 	struct arc_emac_mdio_bus_data *data = &priv->bus_data;
 	struct device_node *np = priv->dev->of_node;
 	const char *name = "Synopsys MII Bus";
+	struct device_node *mdio_node;
 	struct mii_bus *bus;
 	int error;
 
@@ -164,7 +165,13 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
 
 	snprintf(bus->id, MII_BUS_ID_SIZE, "%s", bus->name);
 
-	error = of_mdiobus_register(bus, priv->dev->of_node);
+	/* Backwards compatibility for EMAC nodes without MDIO subnode. */
+	mdio_node = of_get_child_by_name(np, "mdio");
+	if (!mdio_node)
+		mdio_node = of_node_get(np);
+
+	error = of_mdiobus_register(bus, mdio_node);
+	of_node_put(mdio_node);
 	if (error) {
 		mdiobus_free(bus);
 		return dev_err_probe(priv->dev, error,