net: mdio: mscc-miim: add ability to be used in a non-mmio configuration

There are a few Ocelot chips that contain the logic for this bus, but are
controlled externally. Specifically the VSC7511, 7512, 7513, and 7514. In
the externally controlled configurations these registers are not
memory-mapped.

Add support for these non-memory-mapped configurations.
Signed-off-by: Colin Foster <colin.foster@in-advantage.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20220905162132.2943088-3-colin.foster@in-advantage.com

drivers/net/mdio/mdio-mscc-miim.c

@@ -12,6 +12,7 @@
 #include <linux/iopoll.h>
 #include <linux/kernel.h>
 #include <linux/mdio/mdio-mscc-miim.h>
+#include <linux/mfd/ocelot.h>
 #include <linux/module.h>
 #include <linux/of_mdio.h>
 #include <linux/phy.h>
@@ -270,44 +271,25 @@ static int mscc_miim_clk_set(struct mii_bus *bus)
 
 static int mscc_miim_probe(struct platform_device *pdev)
 {
-	struct regmap *mii_regmap, *phy_regmap = NULL;
 	struct device_node *np = pdev->dev.of_node;
+	struct regmap *mii_regmap, *phy_regmap;
 	struct device *dev = &pdev->dev;
-	void __iomem *regs, *phy_regs;
 	struct mscc_miim_dev *miim;
-	struct resource *res;
 	struct mii_bus *bus;
 	int ret;
 
-	regs = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
-	if (IS_ERR(regs)) {
-		dev_err(dev, "Unable to map MIIM registers\n");
-		return PTR_ERR(regs);
-	}
-
-	mii_regmap = devm_regmap_init_mmio(dev, regs, &mscc_miim_regmap_config);
-
-	if (IS_ERR(mii_regmap)) {
-		dev_err(dev, "Unable to create MIIM regmap\n");
-		return PTR_ERR(mii_regmap);
-	}
+	mii_regmap = ocelot_regmap_from_resource(pdev, 0,
+						 &mscc_miim_regmap_config);
+	if (IS_ERR(mii_regmap))
+		return dev_err_probe(dev, PTR_ERR(mii_regmap),
+				     "Unable to create MIIM regmap\n");
 
 	/* This resource is optional */
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
-	if (res) {
-		phy_regs = devm_ioremap_resource(dev, res);
-		if (IS_ERR(phy_regs)) {
-			dev_err(dev, "Unable to map internal phy registers\n");
-			return PTR_ERR(phy_regs);
-		}
-
-		phy_regmap = devm_regmap_init_mmio(dev, phy_regs,
-						   &mscc_miim_phy_regmap_config);
-		if (IS_ERR(phy_regmap)) {
-			dev_err(dev, "Unable to create phy register regmap\n");
-			return PTR_ERR(phy_regmap);
-		}
-	}
+	phy_regmap = ocelot_regmap_from_resource_optional(pdev, 1,
+						 &mscc_miim_phy_regmap_config);
+	if (IS_ERR(phy_regmap))
+		return dev_err_probe(dev, PTR_ERR(phy_regmap),
+				     "Unable to create phy register regmap\n");
 
 	ret = mscc_miim_setup(dev, &bus, "mscc_miim", mii_regmap, 0);
 	if (ret < 0) {