[PATCH 1/3] soc_camera: Add the ability to bind regulators to soc_camedra devices

[Alberto Panizzo <maramaopercheseimorto@gmail.com>]

In certain machines, camera devices are supplied directly
by a number of regulators. This patch add the ability to drive
these regulators directly by the soc_camera driver.

What the machine code have to do to use this functionality is to:
1- Define a number of useful regulator supply descriptions such as:

static struct regulator_consumer_supply camera_reg1_consumers[] = {
	...
	REGULATOR_SUPPLY("camera_reg1", "soc-camera-pdrv.0"),
	...
};

(Pay attention at the .N suffix of "soc-camera-pdrv" in case of
a system with multiple cameras)

2- Define the list of regulators to bind to a specific instance of
   soc-camera-pdrv with their voltages:

static struct soc_camera_regulator_desc soc_camera_regs[] = {
	SOCAM_REG_DESC("camera_reg1", 1300000, 1300000),
	SOCAM_REG_DESC("camera_reg2",   2800000, 2800000),
	...
};

3- Add the list to the corresponding soc_camera_link description:

static struct soc_camera_link iclink_my_camera = {
...
	.soc_regulator_descs		= soc_camera_regs,
	.num_soc_regulator_descs	= ARRAY_SIZE(soc_camera_regs),
};

4- And register it as usual with the platform device description:

static struct platform_device machine_my_camera = {
	.name	= "soc-camera-pdrv",
	.id	= 0,
	.dev	= {
		.platform_data = &iclink_my_camera,
	},
};

Signed-off-by: Alberto Panizzo <maramaopercheseimorto@gmail.com>
---
 drivers/media/video/soc_camera.c |  135 +++++++++++++++++++++++++++++++------
 include/media/soc_camera.h       |   16 +++++
 2 files changed, 129 insertions(+), 22 deletions(-)

diff --git a/drivers/media/video/soc_camera.c b/drivers/media/video/soc_camera.c
index 43848a7..8fc5831 100644
--- a/drivers/media/video/soc_camera.c
+++ b/drivers/media/video/soc_camera.c
@@ -43,6 +43,96 @@ static LIST_HEAD(hosts);
 static LIST_HEAD(devices);
 static DEFINE_MUTEX(list_lock);		/* Protects the list of hosts */
 
+static int soc_camera_setup_regulators(struct soc_camera_device *icd,
+					struct soc_camera_link *icl)
+{
+	int i, ret;
+
+	icd->soc_regulators = kzalloc(icl->num_soc_regulator_descs *
+		sizeof(struct regulator *), GFP_KERNEL);
+	if (!icd->soc_regulators) {
+		dev_err(icd->pdev, "Not enough memory.\n");
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	for (i = 0; i < icl->num_soc_regulator_descs; i++) {
+		dev_dbg(icd->pdev, "Looking for reg:'%s' bound to dev:'%s'",
+			icl->soc_regulator_descs[i].supply,
+			dev_name(icd->pdev));
+		icd->soc_regulators[i] = regulator_get(icd->pdev,
+					    icl->soc_regulator_descs[i].supply);
+		if (IS_ERR(icd->soc_regulators[i])) {
+			icd->soc_regulators[i] = NULL;
+			dev_err(icd->pdev, "Unable to get regulator: \"%s\".\n",
+					icl->soc_regulator_descs[i].supply);
+			ret = -ENODEV;
+			goto free_regs;
+		}
+	}
+
+	icd->num_soc_regulators = icl->num_soc_regulator_descs;
+
+	return 0;
+
+free_regs:
+	for (i--; i >= 0; i--)
+		regulator_put(icd->soc_regulators[i]);
+err:
+	return ret;
+}
+
+static int soc_camera_power_set(struct soc_camera_device *icd,
+				struct soc_camera_link *icl,
+				int power_on)
+{
+	int ret, i;
+
+	for (i = 0; i < icd->num_soc_regulators; i++) {
+		if (power_on) {
+			ret = regulator_set_voltage(icd->soc_regulators[i],
+				icl->soc_regulator_descs[i].value_on_min,
+				icl->soc_regulator_descs[i].value_on_max);
+			if (ret) {
+				dev_err(icd->pdev, "Cannot set '%s' to %d:%d",
+				  icl->soc_regulator_descs[i].supply,
+				  icl->soc_regulator_descs[i].value_on_min,
+				  icl->soc_regulator_descs[i].value_on_max);
+				goto err;
+			}
+
+			ret = regulator_enable(icd->soc_regulators[i]);
+			if (ret < 0) {
+				dev_err(icd->pdev, "Cannot enable reg '%s'",
+					icl->soc_regulator_descs[i].supply);
+				goto err;
+			}
+		} else {
+			ret = regulator_disable(icd->soc_regulators[i]);
+			if (ret) {
+				dev_err(icd->pdev, "Cannot disable reg '%s'",
+					icl->soc_regulator_descs[i].supply);
+				goto err;
+			}
+		}
+	}
+
+	if (icl->power) {
+		ret = icl->power(icd->pdev, power_on);
+		if (ret < 0) {
+			dev_err(icd->pdev,
+				"Platform failed to power-%s the camera.\n",
+				power_on ? "ON" : "OFF");
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	return ret;
+}
+
 const struct soc_camera_format_xlate *soc_camera_xlate_by_fourcc(
 	struct soc_camera_device *icd, unsigned int fourcc)
 {
@@ -375,11 +465,9 @@ static int soc_camera_open(struct file *file)
 			},
 		};
 
-		if (icl->power) {
-			ret = icl->power(icd->pdev, 1);
-			if (ret < 0)
-				goto epower;
-		}
+		ret = soc_camera_power_set(icd, icl, 1);
+		if (ret < 0)
+			goto epower;
 
 		/* The camera could have been already on, try to reset */
 		if (icl->reset)
@@ -425,8 +513,7 @@ esfmt:
 eresume:
 	ici->ops->remove(icd);
 eiciadd:
-	if (icl->power)
-		icl->power(icd->pdev, 0);
+	soc_camera_power_set(icd, icl, 0);
 epower:
 	icd->use_count--;
 	mutex_unlock(&icd->video_lock);
@@ -450,8 +537,7 @@ static int soc_camera_close(struct file *file)
 
 		ici->ops->remove(icd);
 
-		if (icl->power)
-			icl->power(icd->pdev, 0);
+		soc_camera_power_set(icd, icl, 0);
 	}
 
 	if (icd->streamer == file)
@@ -937,18 +1023,18 @@ static int soc_camera_probe(struct device *dev)
 	struct device *control = NULL;
 	struct v4l2_subdev *sd;
 	struct v4l2_mbus_framefmt mf;
-	int ret;
+	int ret = 0, i;
 
 	dev_info(dev, "Probing %s\n", dev_name(dev));
 
-	if (icl->power) {
-		ret = icl->power(icd->pdev, 1);
-		if (ret < 0) {
-			dev_err(dev,
-				"Platform failed to power-on the camera.\n");
-			goto epower;
-		}
-	}
+	if (icl->num_soc_regulator_descs)
+		ret = soc_camera_setup_regulators(icd, icl);
+	if (ret)
+		goto err;
+
+	ret = soc_camera_power_set(icd, icl, 1);
+	if (ret < 0)
+		goto epower;
 
 	/* The camera could have been already on, try to reset */
 	if (icl->reset)
@@ -1021,8 +1107,7 @@ static int soc_camera_probe(struct device *dev)
 
 	ici->ops->remove(icd);
 
-	if (icl->power)
-		icl->power(icd->pdev, 0);
+	soc_camera_power_set(icd, icl, 0);
 
 	mutex_unlock(&icd->video_lock);
 
@@ -1044,9 +1129,11 @@ eadddev:
 evdc:
 	ici->ops->remove(icd);
 eadd:
-	if (icl->power)
-		icl->power(icd->pdev, 0);
+	soc_camera_power_set(icd, icl, 0);
 epower:
+	for (i = icd->num_soc_regulators; i >= 0; i--)
+		regulator_put(icd->soc_regulators[i]);
+err:
 	return ret;
 }
 
@@ -1059,6 +1146,7 @@ static int soc_camera_remove(struct device *dev)
 	struct soc_camera_device *icd = to_soc_camera_dev(dev);
 	struct soc_camera_link *icl = to_soc_camera_link(icd);
 	struct video_device *vdev = icd->vdev;
+	int i;
 
 	BUG_ON(!dev->parent);
 
@@ -1081,6 +1169,9 @@ static int soc_camera_remove(struct device *dev)
 	}
 	soc_camera_free_user_formats(icd);
 
+	for (i = icd->num_soc_regulators; i >= 0; i--)
+		regulator_put(icd->soc_regulators[i]);
+
 	return 0;
 }
 
diff --git a/include/media/soc_camera.h b/include/media/soc_camera.h
index 86e3631..ae589a4 100644
--- a/include/media/soc_camera.h
+++ b/include/media/soc_camera.h
@@ -15,6 +15,7 @@
 #include <linux/device.h>
 #include <linux/mutex.h>
 #include <linux/pm.h>
+#include <linux/regulator/consumer.h>
 #include <linux/videodev2.h>
 #include <media/videobuf-core.h>
 #include <media/v4l2-device.h>
@@ -45,6 +46,8 @@ struct soc_camera_device {
 	struct mutex video_lock;	/* Protects device data */
 	struct file *streamer;		/* stream owner */
 	struct videobuf_queue vb_vidq;
+	struct regulator **soc_regulators;
+	int num_soc_regulators;
 };
 
 struct soc_camera_host {
@@ -96,6 +99,15 @@ struct soc_camera_host_ops {
 #define SOCAM_SENSOR_INVERT_VSYNC	(1 << 3)
 #define SOCAM_SENSOR_INVERT_DATA	(1 << 4)
 
+struct soc_camera_regulator_desc {
+	const char *supply;
+	int value_on_min;
+	int value_on_max;
+};
+
+#define SOCAM_REG_DESC(s, min, max) \
+	{ .supply = s , .value_on_min = min , .value_on_max = max }
+
 struct i2c_board_info;
 
 struct soc_camera_link {
@@ -108,6 +120,10 @@ struct soc_camera_link {
 	const char *module_name;
 	void *priv;
 
+	/* Optional regulators that have to be managed on power on/off events */
+	struct soc_camera_regulator_desc *soc_regulator_descs;
+	int num_soc_regulator_descs;
+
 	/*
 	 * For non-I2C devices platform platform has to provide methods to
 	 * add a device to the system and to remove
-- 
1.6.3.3