gpio/em: Add Device Tree support

Update the Emma Mobile GPIO driver to add DT support.

The patch simply adds a two-cell xlate function and
updates the probe code to allow configuration via DT
using the "ngpios" property plus OF id in the same
style as gpio-mvebu.c. The code is also adjusted to
use postcore_initcall() to force early setup.
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/gpio/gpio-em.c

@@ -231,10 +231,12 @@ static int em_gio_irq_domain_map(struct irq_domain *h, unsigned int virq,
 
 static struct irq_domain_ops em_gio_irq_domain_ops = {
 	.map	= em_gio_irq_domain_map,
+	.xlate	= irq_domain_xlate_twocell,
 };
 
 static int em_gio_probe(struct platform_device *pdev)
 {
+	struct gpio_em_config pdata_dt;
 	struct gpio_em_config *pdata = pdev->dev.platform_data;
 	struct em_gio_priv *p;
 	struct resource *io[2], *irq[2];
@@ -259,8 +261,8 @@ static int em_gio_probe(struct platform_device *pdev)
 	irq[0] = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 	irq[1] = platform_get_resource(pdev, IORESOURCE_IRQ, 1);
 
-	if (!io[0] || !io[1] || !irq[0] || !irq[1] || !pdata) {
-		dev_err(&pdev->dev, "missing IRQ, IOMEM or configuration\n");
+	if (!io[0] || !io[1] || !irq[0] || !irq[1]) {
+		dev_err(&pdev->dev, "missing IRQ or IOMEM\n");
 		ret = -EINVAL;
 		goto err1;
 	}
@@ -279,6 +281,25 @@ static int em_gio_probe(struct platform_device *pdev)
 		goto err2;
 	}
 
+	if (!pdata) {
+		memset(&pdata_dt, 0, sizeof(pdata_dt));
+		pdata = &pdata_dt;
+
+		if (of_property_read_u32(pdev->dev.of_node, "ngpios",
+					 &pdata->number_of_pins)) {
+			dev_err(&pdev->dev, "Missing ngpios OF property\n");
+			ret = -EINVAL;
+			goto err3;
+		}
+
+		ret = of_alias_get_id(pdev->dev.of_node, "gpio");
+		if (ret < 0) {
+			dev_err(&pdev->dev, "Couldn't get OF id\n");
+			goto err3;
+		}
+		pdata->gpio_base = ret * 32; /* 32 GPIOs per instance */
+	}
+
 	gpio_chip = &p->gpio_chip;
 	gpio_chip->direction_input = em_gio_direction_input;
 	gpio_chip->get = em_gio_get;
@@ -366,15 +387,33 @@ static int em_gio_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct of_device_id em_gio_dt_ids[] = {
+	{ .compatible = "renesas,em-gio", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, em_gio_dt_ids);
+
 static struct platform_driver em_gio_device_driver = {
 	.probe		= em_gio_probe,
 	.remove		= em_gio_remove,
 	.driver		= {
 		.name	= "em_gio",
+		.of_match_table = em_gio_dt_ids,
+		.owner		= THIS_MODULE,
 	}
 };
 
-module_platform_driver(em_gio_device_driver);
+static int __init em_gio_init(void)
+{
+	return platform_driver_register(&em_gio_device_driver);
+}
+postcore_initcall(em_gio_init);
+
+static void __exit em_gio_exit(void)
+{
+	platform_driver_unregister(&em_gio_device_driver);
+}
+module_exit(em_gio_exit);
 
 MODULE_AUTHOR("Magnus Damm");
 MODULE_DESCRIPTION("Renesas Emma Mobile GIO Driver");