net: qcom/emac: add shutdown function

The shutdown function halts all DMA and interrupts, so that all
operations are discontinued when the system shuts down, e.g. via
kexec or a forced reboot.

Tested-by: Tyler Baicar <tbaicar@codeaurora.org>
Signed-off-by: Timur Tabi <timur@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/qualcomm/emac/emac.c

@@ -762,6 +762,19 @@ static int emac_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static void emac_shutdown(struct platform_device *pdev)
+{
+	struct net_device *netdev = dev_get_drvdata(&pdev->dev);
+	struct emac_adapter *adpt = netdev_priv(netdev);
+	struct emac_sgmii *sgmii = &adpt->phy;
+
+	/* Closing the SGMII turns off its interrupts */
+	sgmii->close(adpt);
+
+	/* Resetting the MAC turns off all DMA and its interrupts */
+	emac_mac_reset(adpt);
+}
+
 static struct platform_driver emac_platform_driver = {
 	.probe	= emac_probe,
 	.remove	= emac_remove,
@@ -770,6 +783,7 @@ static struct platform_driver emac_platform_driver = {
 		.of_match_table = emac_dt_match,
 		.acpi_match_table = ACPI_PTR(emac_acpi_match),
 	},
+	.shutdown = emac_shutdown,
 };
 
 module_platform_driver(emac_platform_driver);