libcamera: camera_sensor: Generate a sensor ID

The ID is generated from information in the firmware description of the
sensor if available or from module and model information if the sensor
is virtual (for example VIMC).

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/libcamera/camera_sensor.cpp

@@ -13,10 +13,12 @@
 #include <limits.h>
 #include <math.h>
 #include <regex>
+#include <string.h>
 
 #include <libcamera/property_ids.h>
 
 #include "libcamera/internal/formats.h"
+#include "libcamera/internal/sysfs.h"
 #include "libcamera/internal/utils.h"
 
 /**
@@ -204,6 +206,11 @@ int CameraSensor::init()
 	if (ret < 0)
 		return ret;
 
+	/* Generate a unique ID for the sensor. */
+	ret = generateId();
+	if (ret)
+		return ret;
+
 	/* Retrieve and store the camera sensor properties. */
 	const ControlInfoMap &controls = subdev_->controls();
 	int32_t propertyValue;
@@ -541,4 +548,28 @@ std::string CameraSensor::logPrefix() const
 	return "'" + entity_->name() + "'";
 }
 
+int CameraSensor::generateId()
+{
+	const std::string devPath = subdev_->devicePath();
+
+	/* Try to get ID from firmware description. */
+	id_ = sysfs::firmwareNodePath(devPath);
+	if (!id_.empty())
+		return 0;
+
+	/*
+	 * Virtual sensors not described in firmware
+	 *
+	 * Verify it's a platform device and construct ID from the deive path
+	 * and model of sensor.
+	 */
+	if (devPath.find("/sys/devices/platform/", 0) == 0) {
+		id_ = devPath.substr(strlen("/sys/devices/")) + " " + model();
+		return 0;
+	}
+
+	LOG(CameraSensor, Error) << "Can't generate sensor ID";
+	return -EINVAL;
+}
+
 } /* namespace libcamera */