ipa: rpi: Add cam_helper for imx415

As another Starvis sensor, it is near identical to imx290/327.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: David Plowman <david.plowman@raspberrypi.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/ipa/rpi/cam_helper/cam_helper_imx415.cpp

@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2025, Raspberry Pi Ltd
+ *
+ * camera helper for imx415 sensor
+ */
+
+#include <cmath>
+
+#include "cam_helper.h"
+
+using namespace RPiController;
+
+class CamHelperImx415 : public CamHelper
+{
+public:
+	CamHelperImx415();
+	uint32_t gainCode(double gain) const override;
+	double gain(uint32_t gainCode) const override;
+	unsigned int hideFramesStartup() const override;
+	unsigned int hideFramesModeSwitch() const override;
+
+private:
+	/*
+	 * Smallest difference between the frame length and integration time,
+	 * in units of lines.
+	 */
+	static constexpr int frameIntegrationDiff = 8;
+};
+
+CamHelperImx415::CamHelperImx415()
+	: CamHelper({}, frameIntegrationDiff)
+{
+}
+
+uint32_t CamHelperImx415::gainCode(double gain) const
+{
+	int code = 66.6667 * std::log10(gain);
+	return std::max(0, std::min(code, 0xf0));
+}
+
+double CamHelperImx415::gain(uint32_t gainCode) const
+{
+	return std::pow(10, 0.015 * gainCode);
+}
+
+unsigned int CamHelperImx415::hideFramesStartup() const
+{
+	/* On startup, we seem to get 1 bad frame. */
+	return 1;
+}
+
+unsigned int CamHelperImx415::hideFramesModeSwitch() const
+{
+	/* After a mode switch, we seem to get 1 bad frame. */
+	return 1;
+}
+
+static CamHelper *create()
+{
+	return new CamHelperImx415();
+}
+
+static RegisterCamHelper reg("imx415", &create);

src/ipa/rpi/cam_helper/meson.build

@@ -7,6 +7,7 @@ rpi_ipa_cam_helper_sources = files([
     'cam_helper_imx283.cpp',
     'cam_helper_imx290.cpp',
     'cam_helper_imx296.cpp',
+    'cam_helper_imx415.cpp',
     'cam_helper_imx477.cpp',
     'cam_helper_imx519.cpp',
     'cam_helper_imx708.cpp',