net: airoha: Introduce airoha_gdm_dev struct

EN7581 and AN7583 SoCs support connecting multiple external SerDes to GDM3
or GDM4 ports via a hw arbiter that manages the traffic in a TDM manner.
As a result multiple net_devices can connect to the same GDM{3,4} port
and there is a theoretical "1:n" relation between GDM port and
net_devices.
Introduce airoha_gdm_dev struct to collect net_device related info (e.g.
net_device and external phy pointer). Please note this is just a
preliminary patch and we are still supporting a single net_device for
each GDM port. Subsequent patches will add support for multiple net_devices
connected to the same GDM port.

Tested-by: Xuegang Lu <xuegang.lu@airoha.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20260527-airoha-eth-multi-serdes-preliminary-v1-1-ec6ed73ef7fc@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/airoha/airoha_eth.h

@@ -535,10 +535,15 @@ struct airoha_qdma {
 	struct airoha_queue q_rx[AIROHA_NUM_RX_RING];
 };
 
+struct airoha_gdm_dev {
+	struct airoha_gdm_port *port;
+	struct net_device *dev;
+	struct airoha_eth *eth;
+};
+
 struct airoha_gdm_port {
 	struct airoha_qdma *qdma;
-	struct airoha_eth *eth;
+	struct airoha_gdm_dev *dev;
-	struct net_device *dev;
 	int id;
 	int nbq;
 
@@ -662,8 +667,8 @@ static inline bool airoha_is_7583(struct airoha_eth *eth)
 }
 
 int airoha_get_fe_port(struct airoha_gdm_port *port);
-bool airoha_is_valid_gdm_port(struct airoha_eth *eth,
+bool airoha_is_valid_gdm_dev(struct airoha_eth *eth,
-			      struct airoha_gdm_port *port);
+			     struct airoha_gdm_dev *dev);
 
 void airoha_ppe_set_cpu_port(struct airoha_gdm_port *port, u8 ppe_id,
 			     u8 fport);

drivers/net/ethernet/airoha/airoha_ppe.c

@@ -298,12 +298,12 @@ static void airoha_ppe_foe_set_bridge_addrs(struct airoha_foe_bridge *br,
 
 static int airoha_ppe_foe_entry_prepare(struct airoha_eth *eth,
 					struct airoha_foe_entry *hwe,
-					struct net_device *dev, int type,
+					struct net_device *netdev, int type,
 					struct airoha_flow_data *data,
 					int l4proto)
 {
 	u32 qdata = FIELD_PREP(AIROHA_FOE_SHAPER_ID, 0x7f), ports_pad, val;
-	int wlan_etype = -EINVAL, dsa_port = airoha_get_dsa_port(&dev);
+	int wlan_etype = -EINVAL, dsa_port = airoha_get_dsa_port(&netdev);
 	struct airoha_foe_mac_info_common *l2;
 	u8 smac_id = 0xf;
 
@@ -319,10 +319,11 @@ static int airoha_ppe_foe_entry_prepare(struct airoha_eth *eth,
 	hwe->ib1 = val;
 
 	val = FIELD_PREP(AIROHA_FOE_IB2_PORT_AG, 0x1f);
-	if (dev) {
+	if (netdev) {
 		struct airoha_wdma_info info = {};
 
-		if (!airoha_ppe_get_wdma_info(dev, data->eth.h_dest, &info)) {
+		if (!airoha_ppe_get_wdma_info(netdev, data->eth.h_dest,
+					      &info)) {
 			val |= FIELD_PREP(AIROHA_FOE_IB2_NBQ, info.idx) |
 			       FIELD_PREP(AIROHA_FOE_IB2_PSE_PORT,
 					  FE_PSE_PORT_CDM4);
@@ -332,12 +333,14 @@ static int airoha_ppe_foe_entry_prepare(struct airoha_eth *eth,
 				     FIELD_PREP(AIROHA_FOE_MAC_WDMA_WCID,
 						info.wcid);
 		} else {
-			struct airoha_gdm_port *port = netdev_priv(dev);
+			struct airoha_gdm_dev *dev = netdev_priv(netdev);
+			struct airoha_gdm_port *port;
 			u8 pse_port, channel;
 
-			if (!airoha_is_valid_gdm_port(eth, port))
+			if (!airoha_is_valid_gdm_dev(eth, dev))
 				return -EINVAL;
 
+			port = dev->port;
 			if (dsa_port >= 0 || eth->ports[1])
 				pse_port = port->id == 4 ? FE_PSE_PORT_GDM4
 							 : port->id;
@@ -1473,7 +1476,7 @@ void airoha_ppe_check_skb(struct airoha_ppe_dev *dev, struct sk_buff *skb,
 void airoha_ppe_init_upd_mem(struct airoha_gdm_port *port)
 {
 	struct airoha_eth *eth = port->qdma->eth;
-	struct net_device *dev = port->dev;
+	struct net_device *dev = port->dev->dev;
 	const u8 *addr = dev->dev_addr;
 	u32 val;