net: airoha: Enable support for multiple net_devices

In the current codebase airoha_eth driver supports just a single
net_device connected to the Packet Switch Engine (PSE) lan port (GDM1).
As shown in commit 23020f0 ("net: airoha: Introduce ethernet
support for EN7581 SoC"), PSE can switch packets between four GDM ports.
Enable the capability to create a net_device for each GDM port of the
PSE module. Moreover, since the QDMA blocks can be shared between
net_devices, do not stop TX/RX DMA in airoha_dev_stop() if there are
active net_devices for this QDMA block.
This is a preliminary patch to enable flowtable hw offloading for EN7581
SoC.

Co-developed-by: Christian Marangi <ansuelsmth@gmail.com>
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/airoha/airoha_eth.c

@@ -1562,6 +1562,7 @@ static int airoha_dev_open(struct net_device *dev)
 	airoha_qdma_set(qdma, REG_QDMA_GLOBAL_CFG,
 			GLOBAL_CFG_TX_DMA_EN_MASK |
 			GLOBAL_CFG_RX_DMA_EN_MASK);
+	atomic_inc(&qdma->users);
 
 	return 0;
 }
@@ -1577,16 +1578,20 @@ static int airoha_dev_stop(struct net_device *dev)
 	if (err)
 		return err;
 
-	airoha_qdma_clear(qdma, REG_QDMA_GLOBAL_CFG,
-			  GLOBAL_CFG_TX_DMA_EN_MASK |
-			  GLOBAL_CFG_RX_DMA_EN_MASK);
+	for (i = 0; i < ARRAY_SIZE(qdma->q_tx); i++)
+		netdev_tx_reset_subqueue(dev, i);
 
-	for (i = 0; i < ARRAY_SIZE(qdma->q_tx); i++) {
-		if (!qdma->q_tx[i].ndesc)
-			continue;
+	if (atomic_dec_and_test(&qdma->users)) {
+		airoha_qdma_clear(qdma, REG_QDMA_GLOBAL_CFG,
+				  GLOBAL_CFG_TX_DMA_EN_MASK |
+				  GLOBAL_CFG_RX_DMA_EN_MASK);
 
-		airoha_qdma_cleanup_tx_queue(&qdma->q_tx[i]);
-		netdev_tx_reset_subqueue(dev, i);
+		for (i = 0; i < ARRAY_SIZE(qdma->q_tx); i++) {
+			if (!qdma->q_tx[i].ndesc)
+				continue;
+
+			airoha_qdma_cleanup_tx_queue(&qdma->q_tx[i]);
+		}
 	}
 
 	return 0;
@@ -2332,13 +2337,14 @@ static void airoha_metadata_dst_free(struct airoha_gdm_port *port)
 	}
 }
 
-static int airoha_alloc_gdm_port(struct airoha_eth *eth, struct device_node *np)
+static int airoha_alloc_gdm_port(struct airoha_eth *eth,
+				 struct device_node *np, int index)
 {
 	const __be32 *id_ptr = of_get_property(np, "reg", NULL);
 	struct airoha_gdm_port *port;
 	struct airoha_qdma *qdma;
 	struct net_device *dev;
-	int err, index;
+	int err, p;
 	u32 id;
 
 	if (!id_ptr) {
@@ -2347,14 +2353,14 @@ static int airoha_alloc_gdm_port(struct airoha_eth *eth, struct device_node *np)
 	}
 
 	id = be32_to_cpup(id_ptr);
-	index = id - 1;
+	p = id - 1;
 
 	if (!id || id > ARRAY_SIZE(eth->ports)) {
 		dev_err(eth->dev, "invalid gdm port id: %d\n", id);
 		return -EINVAL;
 	}
 
-	if (eth->ports[index]) {
+	if (eth->ports[p]) {
 		dev_err(eth->dev, "duplicate gdm port id: %d\n", id);
 		return -EINVAL;
 	}
@@ -2402,7 +2408,7 @@ static int airoha_alloc_gdm_port(struct airoha_eth *eth, struct device_node *np)
 	port->qdma = qdma;
 	port->dev = dev;
 	port->id = id;
-	eth->ports[index] = port;
+	eth->ports[p] = port;
 
 	err = airoha_metadata_dst_alloc(port);
 	if (err)
@@ -2474,14 +2480,15 @@ static int airoha_probe(struct platform_device *pdev)
 	for (i = 0; i < ARRAY_SIZE(eth->qdma); i++)
 		airoha_qdma_start_napi(&eth->qdma[i]);
 
+	i = 0;
 	for_each_child_of_node(pdev->dev.of_node, np) {
 		if (!of_device_is_compatible(np, "airoha,eth-mac"))
 			continue;
 
 		if (!of_device_is_available(np))
 			continue;
 
-		err = airoha_alloc_gdm_port(eth, np);
+		err = airoha_alloc_gdm_port(eth, np, i++);
 		if (err) {
 			of_node_put(np);
 			goto error_napi_stop;

drivers/net/ethernet/airoha/airoha_eth.h

@@ -13,7 +13,7 @@
 #include <linux/netdevice.h>
 #include <linux/reset.h>
 
-#define AIROHA_MAX_NUM_GDM_PORTS	1
+#define AIROHA_MAX_NUM_GDM_PORTS	4
 #define AIROHA_MAX_NUM_QDMA		2
 #define AIROHA_MAX_DSA_PORTS		7
 #define AIROHA_MAX_NUM_RSTS		3
@@ -212,6 +212,8 @@ struct airoha_qdma {
 	u32 irqmask[QDMA_INT_REG_MAX];
 	int irq;
 
+	atomic_t users;
+
 	struct airoha_tx_irq_queue q_tx_irq[AIROHA_NUM_TX_IRQ];
 
 	struct airoha_queue q_tx[AIROHA_NUM_TX_RING];