[PATCH net-next v2] net: macb: Add shutdown operation support

[Abin Joseph <abin.joseph@amd.com>]

Implement the shutdown hook to ensure clean and complete deactivation of
MACB controller. The shutdown sequence is protected with 'rtnl_lock()'
to serialize access and prevent race conditions while detaching and
closing the network device. This ensure a safe transition when the Kexec
utility calls the shutdown hook, facilitating seamless loading and
booting of a new kernel from the currently running one.

Signed-off-by: Abin Joseph <abin.joseph@amd.com>
---

Changes in v2:
Update the commit description
Update the code to call the close only when admin is up

---
 drivers/net/ethernet/cadence/macb_main.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index e1e8bd2ec155..5bb08f518d54 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -5650,6 +5650,19 @@ static int __maybe_unused macb_runtime_resume(struct device *dev)
 	return 0;
 }
 
+static void macb_shutdown(struct platform_device *pdev)
+{
+	struct net_device *netdev = platform_get_drvdata(pdev);
+
+	rtnl_lock();
+	netif_device_detach(netdev);
+
+	if (netif_running(netdev))
+		dev_close(netdev);
+
+	rtnl_unlock();
+}
+
 static const struct dev_pm_ops macb_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(macb_suspend, macb_resume)
 	SET_RUNTIME_PM_OPS(macb_runtime_suspend, macb_runtime_resume, NULL)
@@ -5663,6 +5676,7 @@ static struct platform_driver macb_driver = {
 		.of_match_table	= of_match_ptr(macb_dt_ids),
 		.pm	= &macb_pm_ops,
 	},
+	.shutdown	= macb_shutdown,
 };
 
 module_platform_driver(macb_driver);
-- 
2.34.1