[PATCH net-next v2 3/8] net: xilinx: tsn: add endpoint MAC driver skeleton

[Srinivas Neeli <srinivas.neeli@amd.com>]

The TSN Endpoint MAC owns the IP's host-side MCDMA data path and is the
netdev physically wired to the CPU. The DSA switch needs this netdev to
exist as its conduit.

Add a platform driver (compatible "xlnx,tsn-ep-mac") for the endpoint.
Register the netdev named "ep", set its MAC address, and provide minimal
netdev and ethtool ops. ndo_open starts the queues and ndo_start_xmit
drops frames.

Co-developed-by: Nagadheeraj Rottela <nagadheeraj.rottela@amd.com>
Signed-off-by: Nagadheeraj Rottela <nagadheeraj.rottela@amd.com>
Signed-off-by: Srinivas Neeli <srinivas.neeli@amd.com>

---
Changes in v2:
- Name the netdev ep%d with NET_NAME_ENUM instead of a fixed "ep", so a second
  IP instance does not clash on register_netdev(). The %d enumeration is what
  NET_NAME_ENUM describes, and it matches the eth%d naming in net/dsa/user.c.
- Drop the mapped but unused register window (ep->regs and its ioremap).
  It was intended for QBV support, which is not part of this series, so the
  endpoint driver does not use it. The mapping will be re-added when QBV
  support lands.
- Use dev_kfree_skb_any() on the drop path, not dev_kfree_skb().
- Drop the mod_devicetable.h include, platform_device.h already pulls it in.
---
 drivers/net/ethernet/xilinx/tsn/Makefile          |   2 +-
 drivers/net/ethernet/xilinx/tsn/xilinx_tsn.h      |  15 +++
 drivers/net/ethernet/xilinx/tsn/xilinx_tsn_ep.c   | 143 ++++++++++++++++++++++
 drivers/net/ethernet/xilinx/tsn/xilinx_tsn_main.c |   3 +
 4 files changed, 162 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/xilinx/tsn/Makefile b/drivers/net/ethernet/xilinx/tsn/Makefile
index 6f99226f3dc8..5886828b386f 100644
--- a/drivers/net/ethernet/xilinx/tsn/Makefile
+++ b/drivers/net/ethernet/xilinx/tsn/Makefile
@@ -1,2 +1,2 @@
 obj-$(CONFIG_XILINX_TSN) += xilinx_tsn.o
-xilinx_tsn-y := xilinx_tsn_main.o
+xilinx_tsn-y := xilinx_tsn_main.o xilinx_tsn_ep.o
diff --git a/drivers/net/ethernet/xilinx/tsn/xilinx_tsn.h b/drivers/net/ethernet/xilinx/tsn/xilinx_tsn.h
new file mode 100644
index 000000000000..b0757e22d1fd
--- /dev/null
+++ b/drivers/net/ethernet/xilinx/tsn/xilinx_tsn.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * AMD/Xilinx TSN Endpoint Ethernet MAC driver, shared definitions.
+ *
+ * Copyright (C) 2026 Advanced Micro Devices, Inc.
+ */
+
+#ifndef _XILINX_TSN_H
+#define _XILINX_TSN_H
+
+#include <linux/platform_device.h>
+
+extern struct platform_driver xlnx_tsn_ep_driver;
+
+#endif /* _XILINX_TSN_H */
diff --git a/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_ep.c b/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_ep.c
new file mode 100644
index 000000000000..089f17a126f5
--- /dev/null
+++ b/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_ep.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AMD/Xilinx TSN Endpoint MAC driver.
+ *
+ * Copyright (C) 2026 Advanced Micro Devices, Inc.
+ */
+
+#include <linux/etherdevice.h>
+#include <linux/ethtool.h>
+#include <linux/if_ether.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/of.h>
+#include <linux/of_net.h>
+#include <linux/platform_device.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+#include "xilinx_tsn.h"
+
+#define DRIVER_NAME			"xilinx_tsn_ep"
+
+/**
+ * struct xlnx_tsn_ep - EP MAC private data, embedded in net_device priv area
+ * @ndev: the conduit netdev ("ep0" for the first IP instance)
+ * @dev: backing device
+ */
+struct xlnx_tsn_ep {
+	struct net_device *ndev;
+	struct device *dev;
+};
+
+static netdev_tx_t ep_start_xmit(struct sk_buff *skb, struct net_device *ndev)
+{
+	dev_kfree_skb_any(skb);
+	DEV_STATS_INC(ndev, tx_dropped);
+	return NETDEV_TX_OK;
+}
+
+static int ep_open(struct net_device *ndev)
+{
+	netif_tx_start_all_queues(ndev);
+
+	return 0;
+}
+
+static int ep_stop(struct net_device *ndev)
+{
+	netif_tx_disable(ndev);
+
+	return 0;
+}
+
+static void ep_get_drvinfo(struct net_device *ndev, struct ethtool_drvinfo *ed)
+{
+	strscpy(ed->driver, DRIVER_NAME, sizeof(ed->driver));
+}
+
+static const struct net_device_ops ep_netdev_ops = {
+	.ndo_open		= ep_open,
+	.ndo_stop		= ep_stop,
+	.ndo_start_xmit		= ep_start_xmit,
+	.ndo_validate_addr	= eth_validate_addr,
+	.ndo_set_mac_address	= eth_mac_addr,
+};
+
+static const struct ethtool_ops ep_ethtool_ops = {
+	.get_drvinfo	= ep_get_drvinfo,
+};
+
+static int xlnx_tsn_ep_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct net_device *ndev;
+	struct xlnx_tsn_ep *ep;
+	u8 mac_addr[ETH_ALEN];
+	int ret;
+
+	ndev = alloc_netdev(sizeof(*ep), "ep%d", NET_NAME_ENUM, ether_setup);
+	if (!ndev)
+		return -ENOMEM;
+
+	SET_NETDEV_DEV(ndev, dev);
+	ndev->netdev_ops = &ep_netdev_ops;
+	ndev->ethtool_ops = &ep_ethtool_ops;
+	ndev->features = NETIF_F_SG;
+
+	ep = netdev_priv(ndev);
+	ep->ndev = ndev;
+	ep->dev = dev;
+
+	ret = of_get_mac_address(dev->of_node, mac_addr);
+	if (ret == -EPROBE_DEFER) {
+		goto err_free_ndev;
+	} else if (!ret && is_valid_ether_addr(mac_addr)) {
+		eth_hw_addr_set(ndev, mac_addr);
+	} else {
+		eth_hw_addr_random(ndev);
+		dev_info(dev, "no valid MAC in DT, using random address %pM\n",
+			 ndev->dev_addr);
+	}
+
+	platform_set_drvdata(pdev, ep);
+
+	ret = register_netdev(ndev);
+	if (ret) {
+		dev_err_probe(dev, ret, "failed to register net device\n");
+		goto err_free_ndev;
+	}
+
+	return 0;
+
+err_free_ndev:
+	free_netdev(ndev);
+	return ret;
+}
+
+static void xlnx_tsn_ep_remove(struct platform_device *pdev)
+{
+	struct xlnx_tsn_ep *ep = platform_get_drvdata(pdev);
+
+	if (!ep)
+		return;
+
+	unregister_netdev(ep->ndev);
+	free_netdev(ep->ndev);
+}
+
+static const struct of_device_id xlnx_tsn_ep_of_match[] = {
+	{ .compatible = "xlnx,tsn-ep-mac" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, xlnx_tsn_ep_of_match);
+
+struct platform_driver xlnx_tsn_ep_driver = {
+	.probe	= xlnx_tsn_ep_probe,
+	.remove	= xlnx_tsn_ep_remove,
+	.driver	= {
+		.name		= DRIVER_NAME,
+		.of_match_table	= xlnx_tsn_ep_of_match,
+	},
+};
diff --git a/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_main.c b/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_main.c
index afe7609c67fb..d33a00dd6d15 100644
--- a/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_main.c
+++ b/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_main.c
@@ -15,6 +15,8 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 
+#include "xilinx_tsn.h"
+
 #define TSN_NUM_CLOCKS		6
 
 /**
@@ -85,6 +87,7 @@ static struct platform_driver tsn_driver = {
 
 static struct platform_driver * const tsn_drivers[] = {
 	&tsn_driver,
+	&xlnx_tsn_ep_driver,
 };
 
 static int __init xlnx_tsn_init(void)

-- 
2.43.0