onewire: w1-gpio: add DT bindings

This patch add DT bindings to the w1-gpio driver, along with some
documentation on how to use them.
Signed-off-by: Daniel Mack <zonque@gmail.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Acked-by: Ville Syrjälä <syrjala@sci.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/w1/w1-gpio.txt

+w1-gpio devicetree bindings
+
+Required properties:
+
+ - compatible: "w1-gpio"
+ - gpios: one or two GPIO specs:
+		- the first one is used as data I/O pin
+		- the second one is optional. If specified, it is used as
+		  enable pin for an external pin pullup.
+
+Optional properties:
+
+ - linux,open-drain: if specified, the data pin is considered in
+		     open-drain mode.
+
+Examples:
+
+	onewire@0 {
+		compatible = "w1-gpio";
+		gpios = <&gpio 126 0>, <&gpio 105 0>;
+	};
+

drivers/w1/masters/w1-gpio.c

@@ -14,6 +14,8 @@
 #include <linux/slab.h>
 #include <linux/w1-gpio.h>
 #include <linux/gpio.h>
+#include <linux/of_platform.h>
+#include <linux/of_gpio.h>
 
 #include "../w1.h"
 #include "../w1_int.h"
@@ -42,12 +44,55 @@ static u8 w1_gpio_read_bit(void *data)
 	return gpio_get_value(pdata->pin) ? 1 : 0;
 }
 
+#ifdef CONFIG_OF
+static struct of_device_id w1_gpio_dt_ids[] = {
+	{ .compatible = "w1-gpio" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, w1_gpio_dt_ids);
+
+static int w1_gpio_probe_dt(struct platform_device *pdev)
+{
+	struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
+	struct device_node *np = pdev->dev.of_node;
+	const struct of_device_id *of_id =
+			of_match_device(w1_gpio_dt_ids, &pdev->dev);
+
+	if (!of_id)
+		return 0;
+
+	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return -ENOMEM;
+
+	if (of_get_property(np, "linux,open-drain", NULL))
+		pdata->is_open_drain = 1;
+
+	pdata->pin = of_get_gpio(np, 0);
+	pdata->ext_pullup_enable_pin = of_get_gpio(np, 1);
+	pdev->dev.platform_data = pdata;
+
+	return 0;
+}
+#else
+static int w1_gpio_probe_dt(struct platform_device *pdev)
+{
+	return 0;
+}
+#endif
+
 static int __init w1_gpio_probe(struct platform_device *pdev)
 {
 	struct w1_bus_master *master;
-	struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
+	struct w1_gpio_platform_data *pdata;
 	int err;
 
+	err = w1_gpio_probe_dt(pdev);
+	if (err < 0)
+		return err;
+
+	pdata = pdev->dev.platform_data;
+
 	if (!pdata)
 		return -ENXIO;
 
@@ -135,6 +180,7 @@ static struct platform_driver w1_gpio_driver = {
 	.driver = {
 		.name	= "w1-gpio",
 		.owner	= THIS_MODULE,
+		.of_match_table = of_match_ptr(w1_gpio_dt_ids),
 	},
 	.remove	= __exit_p(w1_gpio_remove),
 	.suspend = w1_gpio_suspend,