serial: sccnxp: Disable regulator on error

The patch disables the regulator in case of errors, if we have it.
In addition, the patch adds support for deferred regulator probe and
makes error path are a bit clean.
Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/sccnxp.c

@@ -787,10 +787,9 @@ static int sccnxp_probe(struct platform_device *pdev)
 	struct sccnxp_port *s;
 	void __iomem *membase;
 
-	if (!res) {
-		dev_err(&pdev->dev, "Missing memory resource data\n");
-		return -EADDRNOTAVAIL;
-	}
+	membase = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(membase))
+		return PTR_ERR(membase);
 
 	s = devm_kzalloc(&pdev->dev, sizeof(struct sccnxp_port), GFP_KERNEL);
 	if (!s) {
@@ -885,10 +884,20 @@ static int sccnxp_probe(struct platform_device *pdev)
 		break;
 	default:
 		dev_err(&pdev->dev, "Unsupported chip type %i\n", chiptype);
-		ret = -ENOTSUPP;
-		goto err_out;
+		return -ENOTSUPP;
 	}
 
+	s->regulator = devm_regulator_get(&pdev->dev, "vcc");
+	if (!IS_ERR(s->regulator)) {
+		ret = regulator_enable(s->regulator);
+		if (ret) {
+			dev_err(&pdev->dev,
+				"Failed to enable regulator: %i\n", ret);
+			return ret;
+		}
+	} else if (PTR_ERR(s->regulator) == -EPROBE_DEFER)
+		return -EPROBE_DEFER;
+
 	if (!pdata) {
 		dev_warn(&pdev->dev,
 			 "No platform data supplied, using defaults\n");
@@ -919,22 +928,6 @@ static int sccnxp_probe(struct platform_device *pdev)
 		goto err_out;
 	}
 
-	s->regulator = devm_regulator_get(&pdev->dev, "VCC");
-	if (!IS_ERR(s->regulator)) {
-		ret = regulator_enable(s->regulator);
-		if (ret) {
-			dev_err(&pdev->dev,
-				"Failed to enable regulator: %i\n", ret);
-			return ret;
-		}
-	}
-
-	membase = devm_ioremap_resource(&pdev->dev, res);
-	if (IS_ERR(membase)) {
-		ret = PTR_ERR(membase);
-		goto err_out;
-	}
-
 	s->uart.owner		= THIS_MODULE;
 	s->uart.dev_name	= "ttySC";
 	s->uart.major		= SCCNXP_MAJOR;
@@ -997,6 +990,9 @@ static int sccnxp_probe(struct platform_device *pdev)
 	}
 
 err_out:
+	if (!IS_ERR(s->regulator))
+		return regulator_disable(s->regulator);
+
 	return ret;
 }