[media] ov7670: add devicetree support

Add DT support. Use it to get the reset and pwdn pins (if there are any).
Tested with one sensor requiring reset/pwdn and one sensor that doesn't
have reset/pwdn pins.

Signed-off-by: Hans Verkuil <[e-mail]>
Acked-by: Sakari Ailus <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/i2c/ov7670.c

···
 #include <linux/i2c.h>
 #include <linux/delay.h>
 #include <linux/videodev2.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-ctrls.h>
 #include <media/v4l2-mediabus.h>
···
 	};
 	struct ov7670_format_struct *fmt;  /* Current format */
 	struct clk *clk;
+	struct gpio_desc *resetb_gpio;
+	struct gpio_desc *pwdn_gpio;
 	int min_width;			/* Filter out smaller sizes */
 	int min_height;			/* Filter out smaller sizes */
 	int clock_speed;		/* External clock speed (MHz) */
···
 {
 	return ov7670_write_array(sd, ov7670_default_regs);
 }
-
-
 
 static int ov7670_detect(struct v4l2_subdev *sd)
 {
···
 	},
 };
 
+static int ov7670_init_gpio(struct i2c_client *client, struct ov7670_info *info)
+{
+	info->pwdn_gpio = devm_gpiod_get_optional(&client->dev, "powerdown",
+			GPIOD_OUT_LOW);
+	if (IS_ERR(info->pwdn_gpio)) {
+		dev_info(&client->dev, "can't get %s GPIO\n", "powerdown");
+		return PTR_ERR(info->pwdn_gpio);
+	}
+
+	info->resetb_gpio = devm_gpiod_get_optional(&client->dev, "reset",
+			GPIOD_OUT_LOW);
+	if (IS_ERR(info->resetb_gpio)) {
+		dev_info(&client->dev, "can't get %s GPIO\n", "reset");
+		return PTR_ERR(info->resetb_gpio);
+	}
+
+	usleep_range(3000, 5000);
+
+	return 0;
+}
+
 static int ov7670_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
···
 	if (IS_ERR(info->clk))
 		return -EPROBE_DEFER;
 	clk_prepare_enable(info->clk);
+
+	ret = ov7670_init_gpio(client, info);
+	if (ret)
+		goto clk_disable;
 
 	info->clock_speed = clk_get_rate(info->clk) / 1000000;
 	if (info->clock_speed < 10 || info->clock_speed > 48) {
···
 };
 MODULE_DEVICE_TABLE(i2c, ov7670_id);
 
+#if IS_ENABLED(CONFIG_OF)
+static const struct of_device_id ov7670_of_match[] = {
+	{ .compatible = "ovti,ov7670", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, ov7670_of_match);
+#endif
+
 static struct i2c_driver ov7670_driver = {
 	.driver = {
 		.name	= "ov7670",
+		.of_match_table = of_match_ptr(ov7670_of_match),
 	},
 	.probe		= ov7670_probe,
 	.remove		= ov7670_remove,