libcamera: ipa: raspberrypi: Add support for ov9281 sensor

The necessary tuning file and CamHelper is added for the ov9281 sensor.

The ov9281 is a 1280x800 monochrome global shutter sensor. To enable
it, please add

dtoverlay=ov9281

to the /boot/config.txt file and reboot the Pi.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 65 insertions, 0 deletions

diff --git a/src/ipa/raspberrypi/cam_helper_ov9281.cpp b/src/ipa/raspberrypi/cam_helper_ov9281.cpp
new file mode 100644
index 00000000..54091f83
--- /dev/null
+++ b/src/ipa/raspberrypi/cam_helper_ov9281.cpp
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2021, Raspberry Pi (Trading) Limited
+ *
+ * cam_helper_ov9281.cpp - camera information for ov9281 sensor
+ */
+
+#include <assert.h>
+
+#include "cam_helper.hpp"
+
+using namespace RPiController;
+
+class CamHelperOv9281 : public CamHelper
+{
+public:
+	CamHelperOv9281();
+	uint32_t GainCode(double gain) const override;
+	double Gain(uint32_t gain_code) const override;
+	void GetDelays(int &exposure_delay, int &gain_delay,
+		       int &vblank_delay) const override;
+
+private:
+	/*
+	 * Smallest difference between the frame length and integration time,
+	 * in units of lines.
+	 */
+	static constexpr int frameIntegrationDiff = 4;
+};
+
+/*
+ * OV9281 doesn't output metadata, so we have to use the "unicam parser" which
+ * works by counting frames.
+ */
+
+CamHelperOv9281::CamHelperOv9281()
+	: CamHelper(nullptr, frameIntegrationDiff)
+{
+}
+
+uint32_t CamHelperOv9281::GainCode(double gain) const
+{
+	return static_cast<uint32_t>(gain * 16.0);
+}
+
+double CamHelperOv9281::Gain(uint32_t gain_code) const
+{
+	return static_cast<double>(gain_code) / 16.0;
+}
+
+void CamHelperOv9281::GetDelays(int &exposure_delay, int &gain_delay,
+				int &vblank_delay) const
+{
+	/* The driver appears to behave as follows: */
+	exposure_delay = 2;
+	gain_delay = 2;
+	vblank_delay = 2;
+}
+
+static CamHelper *Create()
+{
+	return new CamHelperOv9281();
+}
+
+static RegisterCamHelper reg("ov9281", &Create);