net: cpsw: Add am33xx MACID readout

This patch adds a function to get the MACIDs from the am33xx SoC
control module registers which hold unique vendor MACIDs. This is only
used if of_get_mac_address() fails to get a valid mac address.

Signed-off-by: Markus Pargmann <[e-mail]>
Reviewed-by: Wolfram Sang <[e-mail]>
Tested-by: Steven Rostedt <[e-mail]>
Acked-by: Tony Lindgren <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

Documentation/devicetree/bindings/net/cpsw.txt

···
 - ti,hwmods		: Must be "cpgmac0"
 - no_bd_ram		: Must be 0 or 1
 - dual_emac		: Specifies Switch to act as Dual EMAC
+- syscon		: Phandle to the system control device node, which is
+			  the control module device of the am33x
 
 Slave Properties:
 Required properties:
···
 		active_slave = <0>;
 		cpts_clock_mult = <0x80000000>;
 		cpts_clock_shift = <29>;
+		syscon = <&cm>;
 		cpsw_emac0: slave@0 {
 			phy_id = <&davinci_mdio>, <0>;
 			phy-mode = "rgmii-txid";
···
 		active_slave = <0>;
 		cpts_clock_mult = <0x80000000>;
 		cpts_clock_shift = <29>;
+		syscon = <&cm>;
 		cpsw_emac0: slave@0 {
 			phy_id = <&davinci_mdio>, <0>;
 			phy-mode = "rgmii-txid";

drivers/net/ethernet/ti/Kconfig

···
 	select TI_DAVINCI_CPDMA
 	select TI_DAVINCI_MDIO
 	select TI_CPSW_PHY_SEL
+	select MFD_SYSCON
+	select REGMAP
 	---help---
 	  This driver supports TI's CPSW Ethernet Switch.
 

drivers/net/ethernet/ti/cpsw.c

···
 #include <linux/of_net.h>
 #include <linux/of_device.h>
 #include <linux/if_vlan.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
 
 #include <linux/pinctrl/consumer.h>
 
···
 	slave->port_vlan = data->dual_emac_res_vlan;
 }
 
+#define AM33XX_CTRL_MAC_LO_REG(id) (0x630 + 0x8 * id)
+#define AM33XX_CTRL_MAC_HI_REG(id) (0x630 + 0x8 * id + 0x4)
+
+static int cpsw_am33xx_cm_get_macid(struct device *dev, int slave,
+		u8 *mac_addr)
+{
+	u32 macid_lo;
+	u32 macid_hi;
+	struct regmap *syscon;
+
+	syscon = syscon_regmap_lookup_by_phandle(dev->of_node, "syscon");
+	if (IS_ERR(syscon)) {
+		if (PTR_ERR(syscon) == -ENODEV)
+			return 0;
+		return PTR_ERR(syscon);
+	}
+
+	regmap_read(syscon, AM33XX_CTRL_MAC_LO_REG(slave), &macid_lo);
+	regmap_read(syscon, AM33XX_CTRL_MAC_HI_REG(slave), &macid_hi);
+
+	mac_addr[5] = (macid_lo >> 8) & 0xff;
+	mac_addr[4] = macid_lo & 0xff;
+	mac_addr[3] = (macid_hi >> 24) & 0xff;
+	mac_addr[2] = (macid_hi >> 16) & 0xff;
+	mac_addr[1] = (macid_hi >> 8) & 0xff;
+	mac_addr[0] = macid_hi & 0xff;
+
+	return 0;
+}
+
 static int cpsw_probe_dt(struct cpsw_platform_data *data,
 			 struct platform_device *pdev)
 {
···
 			 PHY_ID_FMT, mdio->name, phyid);
 
 		mac_addr = of_get_mac_address(slave_node);
-		if (mac_addr)
+		if (mac_addr) {
 			memcpy(slave_data->mac_addr, mac_addr, ETH_ALEN);
+		} else {
+			if (of_machine_is_compatible("ti,am33xx")) {
+				ret = cpsw_am33xx_cm_get_macid(&pdev->dev, i,
+							slave_data->mac_addr);
+				if (ret)
+					return ret;
+			}
+		}
 
 		slave_data->phy_if = of_get_phy_mode(slave_node);
 		if (slave_data->phy_if < 0) {