mfd: bcm2835-pm: Use 'reg-names' to get resources

If available in firmware, find resources by their 'reg-names' position
instead of relying on hardcoded offsets. Care is taken to support old
firmware nonetheless.
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220625113619.15944-7-stefan.wahren@i2se.com

drivers/mfd/bcm2835-pm.c

@@ -25,9 +25,40 @@ static const struct mfd_cell bcm2835_power_devs[] = {
 	{ .name = "bcm2835-power" },
 };
 
+static int bcm2835_pm_get_pdata(struct platform_device *pdev,
+				struct bcm2835_pm *pm)
+{
+	if (of_find_property(pm->dev->of_node, "reg-names", NULL)) {
+		struct resource *res;
+
+		pm->base = devm_platform_ioremap_resource_byname(pdev, "pm");
+		if (IS_ERR(pm->base))
+			return PTR_ERR(pm->base);
+
+		res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "asb");
+		if (res) {
+			pm->asb = devm_ioremap_resource(&pdev->dev, res);
+			if (IS_ERR(pm->asb))
+				pm->asb = NULL;
+		}
+
+		return 0;
+	}
+
+	/* If no 'reg-names' property is found we can assume we're using old DTB. */
+	pm->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(pm->base))
+		return PTR_ERR(pm->base);
+
+	pm->asb = devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(pm->asb))
+		pm->asb = NULL;
+
+	return 0;
+}
+
 static int bcm2835_pm_probe(struct platform_device *pdev)
 {
-	struct resource *res;
 	struct device *dev = &pdev->dev;
 	struct bcm2835_pm *pm;
 	int ret;
@@ -39,10 +70,9 @@ static int bcm2835_pm_probe(struct platform_device *pdev)
 
 	pm->dev = dev;
 
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	pm->base = devm_ioremap_resource(dev, res);
-	if (IS_ERR(pm->base))
-		return PTR_ERR(pm->base);
+	ret = bcm2835_pm_get_pdata(pdev, pm);
+	if (ret)
+		return ret;
 
 	ret = devm_mfd_add_devices(dev, -1,
 				   bcm2835_pm_devs, ARRAY_SIZE(bcm2835_pm_devs),
@@ -50,24 +80,15 @@ static int bcm2835_pm_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	/* We'll use the presence of the AXI ASB regs in the
+	/*
+	 * We'll use the presence of the AXI ASB regs in the
 	 * bcm2835-pm binding as the key for whether we can reference
 	 * the full PM register range and support power domains.
 	 */
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
-	if (res) {
-		pm->asb = devm_ioremap_resource(dev, res);
-		if (IS_ERR(pm->asb))
-			return PTR_ERR(pm->asb);
-
-		ret = devm_mfd_add_devices(dev, -1,
-					   bcm2835_power_devs,
-					   ARRAY_SIZE(bcm2835_power_devs),
-					   NULL, 0, NULL);
-		if (ret)
-			return ret;
-	}
-
+	if (pm->asb)
+		return devm_mfd_add_devices(dev, -1, bcm2835_power_devs,
+					    ARRAY_SIZE(bcm2835_power_devs),
+					    NULL, 0, NULL);
 	return 0;
 }