ipa: raspberrypi: Add autofocus algorithm interface headers

Add a new AfAlgorithm class that defines the interface for the Raspberry Pi
autofocus algorithm.

Add an AfStatus structure that returns the results of the autofocus algorithm
back to the IPA.

Add a structure for PDAF statistics provided by supported sensors for use with
an autofocus algorithm. This structure is currently based on the IMX708's PDAF
"Type 1" statistics.

Signed-off-by: Nick Hollinghurst <nick.hollinghurst@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/raspberrypi/controller/af_algorithm.h

@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Raspberry Pi Ltd
+ *
+ * af_algorithm.hpp - auto focus algorithm interface
+ */
+#pragma once
+
+#include <optional>
+
+#include <libcamera/base/span.h>
+
+#include "algorithm.h"
+
+namespace RPiController {
+
+class AfAlgorithm : public Algorithm
+{
+public:
+	AfAlgorithm(Controller *controller)
+		: Algorithm(controller) {}
+
+	/*
+	 * An autofocus algorithm should provide the following calls.
+	 *
+	 * Where a ControlList combines a change of AfMode with other AF
+	 * controls, setMode() should be called first, to ensure the
+	 * algorithm will be in the correct state to handle controls.
+	 *
+	 * setLensPosition() returns true if the mode was AfModeManual and
+	 * the lens position has changed, otherwise returns false. When it
+	 * returns true, hwpos should be sent immediately to the lens driver.
+	 *
+	 * getMode() is provided mainly for validating controls.
+	 * getLensPosition() is provided for populating DeviceStatus.
+	 */
+
+	enum AfRange { AfRangeNormal = 0,
+		       AfRangeMacro,
+		       AfRangeFull,
+		       AfRangeMax };
+
+	enum AfSpeed { AfSpeedNormal = 0,
+		       AfSpeedFast,
+		       AfSpeedMax };
+
+	enum AfMode { AfModeManual = 0,
+		      AfModeAuto,
+		      AfModeContinuous };
+
+	enum AfPause { AfPauseImmediate = 0,
+		       AfPauseDeferred,
+		       AfPauseResume };
+
+	virtual void setRange([[maybe_unused]] AfRange range)
+	{
+	}
+	virtual void setSpeed([[maybe_unused]] AfSpeed speed)
+	{
+	}
+	virtual void setMetering([[maybe_unused]] bool use_windows)
+	{
+	}
+	virtual void setWindows([[maybe_unused]] libcamera::Span<libcamera::Rectangle const> const &wins)
+	{
+	}
+	virtual void setMode(AfMode mode) = 0;
+	virtual AfMode getMode() const = 0;
+	virtual bool setLensPosition(double dioptres, int32_t *hwpos) = 0;
+	virtual std::optional<double> getLensPosition() const = 0;
+	virtual void triggerScan() = 0;
+	virtual void cancelScan() = 0;
+	virtual void pause(AfPause pause) = 0;
+};
+
+} // namespace RPiController