stmmac: intel: add phy-mode and fixed-link ACPI _DSD setting support

Currently, phy_interface for TSN controller instance is set based on its
PCI Device ID. For SGMII PHY interface, phy_interface default to
PHY_INTERFACE_MODE_SGMII. As C37 AN supports both SGMII and 1000BASE-X
mode, we add support for 'phy-mode' ACPI _DSD for port-specific
and customer platform specific customization.

v3: use fwnode_get_phy_mode() as suggested by Andrew Lunn in
https://patchwork.kernel.org/comment/24895330/

v2:
For platform that sets 'fixed-link' using ACPI _DSD, we will unset
xpcs_an_inband within stmmac. Thanks to Russell King for his comment in
https://patchwork.kernel.org/comment/24890222/

v1:
Thanks to Andrew Lunn's guidance in
https://patchwork.kernel.org/comment/24827101/

Tested-by: Emilio Riva <emilio.riva@ericsson.com>
Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwmac-intel.c

@@ -442,6 +442,7 @@ static void common_default_data(struct plat_stmmacenet_data *plat)
 static int intel_mgbe_common_data(struct pci_dev *pdev,
 				  struct plat_stmmacenet_data *plat)
 {
+	struct fwnode_handle *fwnode;
 	char clk_name[20];
 	int ret;
 	int i;
@@ -560,13 +561,42 @@ static int intel_mgbe_common_data(struct pci_dev *pdev,
 	/* Use the last Rx queue */
 	plat->vlan_fail_q = plat->rx_queues_to_use - 1;
 
+	/* For fixed-link setup, we allow phy-mode setting */
+	fwnode = dev_fwnode(&pdev->dev);
+	if (fwnode) {
+		int phy_mode;
+
+		/* "phy-mode" setting is optional. If it is set,
+		 *  we allow either sgmii or 1000base-x for now.
+		 */
+		phy_mode = fwnode_get_phy_mode(fwnode);
+		if (phy_mode >= 0) {
+			if (phy_mode == PHY_INTERFACE_MODE_SGMII ||
+			    phy_mode == PHY_INTERFACE_MODE_1000BASEX)
+				plat->phy_interface = phy_mode;
+			else
+				dev_warn(&pdev->dev, "Invalid phy-mode\n");
+		}
+	}
+
 	/* Intel mgbe SGMII interface uses pcs-xcps */
 	if (plat->phy_interface == PHY_INTERFACE_MODE_SGMII ||
 	    plat->phy_interface == PHY_INTERFACE_MODE_1000BASEX) {
 		plat->mdio_bus_data->has_xpcs = true;
 		plat->mdio_bus_data->xpcs_an_inband = true;
 	}
 
+	/* For fixed-link setup, we clear xpcs_an_inband */
+	if (fwnode) {
+		struct fwnode_handle *fixed_node;
+
+		fixed_node = fwnode_get_named_child_node(fwnode, "fixed-link");
+		if (fixed_node)
+			plat->mdio_bus_data->xpcs_an_inband = false;
+
+		fwnode_handle_put(fixed_node);
+	}
+
 	/* Ensure mdio bus scan skips intel serdes and pcs-xpcs */
 	plat->mdio_bus_data->phy_mask = 1 << INTEL_MGBE_ADHOC_ADDR;
 	plat->mdio_bus_data->phy_mask |= 1 << INTEL_MGBE_XPCS_ADDR;