From 34220db79008820c110473fe804cf02af3037889 Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.org>
Date: Thu, 18 May 2017 15:42:34 +0100
Subject: [PATCH 323/454] ov5647: Add support for PWDN GPIO.

Add support for an optional GPIO connected to PWDN on the sensor.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
---
 drivers/media/i2c/ov5647.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

--- a/drivers/media/i2c/ov5647.c
+++ b/drivers/media/i2c/ov5647.c
@@ -21,6 +21,7 @@
 
 #include <linux/clk.h>
 #include <linux/delay.h>
+#include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/io.h>
@@ -35,6 +36,13 @@
 
 #define SENSOR_NAME "ov5647"
 
+/*
+ * From the datasheet, "20ms after PWDN goes low or 20ms after RESETB goes
+ * high if reset is inserted after PWDN goes high, host can access sensor's
+ * SCCB to initialize sensor."
+ */
+#define PWDN_ACTIVE_DELAY_MS	20
+
 #define OV5647_SW_RESET		0x0103
 #define OV5647_REG_CHIPID_H	0x300A
 #define OV5647_REG_CHIPID_L	0x300B
@@ -77,6 +85,7 @@ struct ov5647 {
 	unsigned int			height;
 	int				power_count;
 	struct clk			*xclk;
+	struct gpio_desc		*pwdn;
 };
 
 static inline struct ov5647 *to_state(struct v4l2_subdev *sd)
@@ -334,6 +343,11 @@ static int ov5647_sensor_power(struct v4
 	if (on && !ov5647->power_count)	{
 		dev_dbg(&client->dev, "OV5647 power on\n");
 
+		if (ov5647->pwdn) {
+			gpiod_set_value(ov5647->pwdn, 0);
+			msleep(PWDN_ACTIVE_DELAY_MS);
+		}
+
 		ret = clk_prepare_enable(ov5647->xclk);
 		if (ret < 0) {
 			dev_err(&client->dev, "clk prepare enable failed\n");
@@ -371,6 +385,8 @@ static int ov5647_sensor_power(struct v4
 			dev_dbg(&client->dev, "soft stby failed\n");
 
 		clk_disable_unprepare(ov5647->xclk);
+
+		gpiod_set_value(ov5647->pwdn, 1);
 	}
 
 	/* Update the power count. */
@@ -583,6 +599,10 @@ static int ov5647_probe(struct i2c_clien
 		return -EINVAL;
 	}
 
+	/* Request the power down GPIO asserted */
+	sensor->pwdn = devm_gpiod_get_optional(&client->dev, "pwdn",
+					       GPIOD_OUT_HIGH);
+
 	mutex_init(&sensor->lock);
 
 	sd = &sensor->sd;
@@ -596,7 +616,15 @@ static int ov5647_probe(struct i2c_clien
 	if (ret < 0)
 		goto mutex_remove;
 
+	if (sensor->pwdn) {
+		gpiod_set_value(sensor->pwdn, 0);
+		msleep(PWDN_ACTIVE_DELAY_MS);
+	}
+
 	ret = ov5647_detect(sd);
+
+	gpiod_set_value(sensor->pwdn, 1);
+
 	if (ret < 0)
 		goto error;