ipa: rpi: Add vd55g1 support for rpi

The cam_helper gain formula and frameIntegrationDiff can be found in the
vd55g1 user manual.

Signed-off-by: Benjamin Mugnier <benjamin.mugnier@foss.st.com>
Acked-by: Naushir Patuck <naush@raspberrypi.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/ipa/rpi/cam_helper/cam_helper_vd55g1.cpp

@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) STMicroelectronics SA 2025
+ *
+ * Camera information for vd55g1 sensor
+ */
+
+#include <assert.h>
+
+#include "cam_helper.h"
+
+using namespace RPiController;
+
+class CamHelperVd55g1 : public CamHelper
+{
+public:
+	CamHelperVd55g1();
+	uint32_t gainCode(double gain) const override;
+	double gain(uint32_t gainCode) const override;
+
+private:
+	/*
+	 * Smallest difference between the frame length and integration time,
+	 * in units of lines.
+	 */
+	static constexpr int frameIntegrationDiff = 64;
+};
+
+CamHelperVd55g1::CamHelperVd55g1()
+	: CamHelper({}, frameIntegrationDiff)
+{
+}
+
+uint32_t CamHelperVd55g1::gainCode(double gain) const
+{
+	return static_cast<uint32_t>(32.0 - 32.0 / gain);
+}
+
+double CamHelperVd55g1::gain(uint32_t gainCode) const
+{
+	return 32.0 / (32.0 - static_cast<double>(gainCode));
+}
+
+static CamHelper *create()
+{
+	return new CamHelperVd55g1();
+}
+
+static RegisterCamHelper reg("vd55g1", &create);

src/ipa/rpi/cam_helper/meson.build

@@ -14,6 +14,7 @@ rpi_ipa_cam_helper_sources = files([
     'cam_helper_ov64a40.cpp',
     'cam_helper_ov7251.cpp',
     'cam_helper_ov9281.cpp',
+    'cam_helper_vd55g1.cpp',
     'cam_helper_vd56g3.cpp',
     'md_parser_smia.cpp',
 ])