gpio/xilinx: Convert the driver to platform device interface

This way we do not need to transverse the device tree manually and we
support hot plugged devices.

Also Implement remove callback so the driver can be unloaded
Acked-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-xilinx.c

@@ -44,12 +44,18 @@
  * gpio_state: GPIO state shadow register
  * gpio_dir: GPIO direction shadow register
  * gpio_lock: Lock used for synchronization
+ * inited: True if the port has been inited
  */
 struct xgpio_instance {
 	struct of_mm_gpio_chip mmchip;
 	u32 gpio_state;
 	u32 gpio_dir;
 	spinlock_t gpio_lock;
+	bool inited;
+};
+
+struct xgpio {
+	struct xgpio_instance port[2];
 };
 
 /**
@@ -171,25 +177,57 @@ static void xgpio_save_regs(struct of_mm_gpio_chip *mm_gc)
 	xgpio_writereg(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir);
 }
 
+/**
+ * xgpio_remove - Remove method for the GPIO device.
+ * @pdev: pointer to the platform device
+ *
+ * This function remove gpiochips and frees all the allocated resources.
+ */
+static int xgpio_remove(struct platform_device *pdev)
+{
+	struct xgpio *xgpio = platform_get_drvdata(pdev);
+	int i;
+
+	for (i = 0; i < 2; i++) {
+		if (!xgpio->port[i].inited)
+			continue;
+		gpiochip_remove(&xgpio->port[i].mmchip.gc);
+
+		if (i == 1)
+			xgpio->port[i].mmchip.regs -= XGPIO_CHANNEL_OFFSET;
+
+		iounmap(xgpio->port[i].mmchip.regs);
+		kfree(xgpio->port[i].mmchip.gc.label);
+	}
+
+	return 0;
+}
+
 /**
  * xgpio_of_probe - Probe method for the GPIO device.
- * @np: pointer to device tree node
+ * @pdev: pointer to the platform device
  *
  * This function probes the GPIO device in the device tree. It initializes the
  * driver data structure. It returns 0, if the driver is bound to the GPIO
  * device, or a negative value if there is an error.
  */
-static int xgpio_of_probe(struct device_node *np)
+static int xgpio_probe(struct platform_device *pdev)
 {
+	struct xgpio *xgpio;
 	struct xgpio_instance *chip;
 	int status = 0;
+	struct device_node *np = pdev->dev.of_node;
 	const u32 *tree_info;
 	u32 ngpio;
 
-	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
-	if (!chip)
+	xgpio = devm_kzalloc(&pdev->dev, sizeof(*xgpio), GFP_KERNEL);
+	if (!xgpio)
 		return -ENOMEM;
 
+	platform_set_drvdata(pdev, xgpio);
+
+	chip = &xgpio->port[0];
+
 	/* Update GPIO state shadow register with default value */
 	of_property_read_u32(np, "xlnx,dout-default", &chip->gpio_state);
 
@@ -209,6 +247,7 @@ static int xgpio_of_probe(struct device_node *np)
 
 	spin_lock_init(&chip->gpio_lock);
 
+	chip->mmchip.gc.dev = &pdev->dev;
 	chip->mmchip.gc.direction_input = xgpio_dir_in;
 	chip->mmchip.gc.direction_output = xgpio_dir_out;
 	chip->mmchip.gc.get = xgpio_get;
@@ -219,20 +258,18 @@ static int xgpio_of_probe(struct device_node *np)
 	/* Call the OF gpio helper to setup and register the GPIO device */
 	status = of_mm_gpiochip_add(np, &chip->mmchip);
 	if (status) {
-		kfree(chip);
 		pr_err("%s: error in probe function with status %d\n",
 		       np->full_name, status);
 		return status;
 	}
+	chip->inited = true;
 
 	pr_info("XGpio: %s: registered, base is %d\n", np->full_name,
 							chip->mmchip.gc.base);
 
 	tree_info = of_get_property(np, "xlnx,is-dual", NULL);
 	if (tree_info && be32_to_cpup(tree_info)) {
-		chip = kzalloc(sizeof(*chip), GFP_KERNEL);
-		if (!chip)
-			return -ENOMEM;
+		chip = &xgpio->port[1];
 
 		/* Update GPIO state shadow register with default value */
 		of_property_read_u32(np, "xlnx,dout-default-2",
@@ -254,6 +291,7 @@ static int xgpio_of_probe(struct device_node *np)
 
 		spin_lock_init(&chip->gpio_lock);
 
+		chip->mmchip.gc.dev = &pdev->dev;
 		chip->mmchip.gc.direction_input = xgpio_dir_in;
 		chip->mmchip.gc.direction_output = xgpio_dir_out;
 		chip->mmchip.gc.get = xgpio_get;
@@ -264,7 +302,7 @@ static int xgpio_of_probe(struct device_node *np)
 		/* Call the OF gpio helper to setup and register the GPIO dev */
 		status = of_mm_gpiochip_add(np, &chip->mmchip);
 		if (status) {
-			kfree(chip);
+			xgpio_remove(pdev);
 			pr_err("%s: error in probe function with status %d\n",
 			np->full_name, status);
 			return status;
@@ -272,6 +310,7 @@ static int xgpio_of_probe(struct device_node *np)
 
 		/* Add dual channel offset */
 		chip->mmchip.regs += XGPIO_CHANNEL_OFFSET;
+		chip->inited = true;
 
 		pr_info("XGpio: %s: dual channel registered, base is %d\n",
 					np->full_name, chip->mmchip.gc.base);
@@ -285,19 +324,29 @@ static const struct of_device_id xgpio_of_match[] = {
 	{ /* end of list */ },
 };
 
-static int __init xgpio_init(void)
-{
-	struct device_node *np;
+MODULE_DEVICE_TABLE(of, xgpio_of_match);
 
-	for_each_matching_node(np, xgpio_of_match)
-		xgpio_of_probe(np);
+static struct platform_driver xgpio_plat_driver = {
+	.probe		= xgpio_probe,
+	.remove		= xgpio_remove,
+	.driver		= {
+			.name = "gpio-xilinx",
+			.of_match_table	= xgpio_of_match,
+	},
+};
 
-	return 0;
+static int __init xgpio_init(void)
+{
+	return platform_driver_register(&xgpio_plat_driver);
 }
 
-/* Make sure we get initialized before anyone else tries to use us */
 subsys_initcall(xgpio_init);
-/* No exit call at the moment as we cannot unregister of GPIO chips */
+
+static void __exit xgpio_exit(void)
+{
+	platform_driver_unregister(&xgpio_plat_driver);
+}
+module_exit(xgpio_exit);
 
 MODULE_AUTHOR("Xilinx, Inc.");
 MODULE_DESCRIPTION("Xilinx GPIO driver");