libcamera: ipa: Raspberry Pi IPA

Initial implementation of the Raspberry Pi (BCM2835) libcamera IPA and
associated libraries.

All code is licensed under the BSD-2-Clause terms.
Copyright (c) 2019-2020 Raspberry Pi Trading Ltd.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/ipa/raspberrypi/cam_helper_imx477.cpp

@@ -0,0 +1,162 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2020, Raspberry Pi (Trading) Limited
+ *
+ * cam_helper_imx477.cpp - camera helper for imx477 sensor
+ */
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "cam_helper.hpp"
+#include "md_parser.hpp"
+
+using namespace RPi;
+
+/* Metadata parser implementation specific to Sony IMX477 sensors. */
+
+class MdParserImx477 : public MdParserSmia
+{
+public:
+	MdParserImx477();
+	Status Parse(void *data) override;
+	Status GetExposureLines(unsigned int &lines) override;
+	Status GetGainCode(unsigned int &gain_code) override;
+private:
+	/* Offset of the register's value in the metadata block. */
+	int reg_offsets_[4];
+	/* Value of the register, once read from the metadata block. */
+	int reg_values_[4];
+};
+
+class CamHelperImx477 : public CamHelper
+{
+public:
+	CamHelperImx477();
+	uint32_t GainCode(double gain) const override;
+	double Gain(uint32_t gain_code) const override;
+	bool SensorEmbeddedDataPresent() const override;
+	CamTransform GetOrientation() const override;
+};
+
+CamHelperImx477::CamHelperImx477()
+	: CamHelper(new MdParserImx477())
+{
+}
+
+uint32_t CamHelperImx477::GainCode(double gain) const
+{
+	return static_cast<uint32_t>(1024 - 1024 / gain);
+}
+
+double CamHelperImx477::Gain(uint32_t gain_code) const
+{
+	return 1024.0 / (1024 - gain_code);
+}
+
+bool CamHelperImx477::SensorEmbeddedDataPresent() const
+{
+	return true;
+}
+
+CamTransform CamHelperImx477::GetOrientation() const
+{
+	/* Camera is "upside down" on this board. */
+	return CamTransform_HFLIP | CamTransform_VFLIP;
+}
+
+static CamHelper *Create()
+{
+	return new CamHelperImx477();
+}
+
+static RegisterCamHelper reg("imx477", &Create);
+
+/*
+ * We care about two gain registers and a pair of exposure registers. Their
+ * I2C addresses from the Sony IMX477 datasheet:
+ */
+#define EXPHI_REG 0x0202
+#define EXPLO_REG 0x0203
+#define GAINHI_REG 0x0204
+#define GAINLO_REG 0x0205
+
+/*
+ * Index of each into the reg_offsets and reg_values arrays. Must be in register
+ * address order.
+ */
+#define EXPHI_INDEX 0
+#define EXPLO_INDEX 1
+#define GAINHI_INDEX 2
+#define GAINLO_INDEX 3
+
+MdParserImx477::MdParserImx477()
+{
+	reg_offsets_[0] = reg_offsets_[1] = reg_offsets_[2] = reg_offsets_[3] = -1;
+}
+
+MdParser::Status MdParserImx477::Parse(void *data)
+{
+	bool try_again = false;
+
+	if (reset_) {
+		/*
+		 * Search again through the metadata for the gain and exposure
+		 * registers.
+		 */
+		assert(bits_per_pixel_);
+		assert(num_lines_ || buffer_size_bytes_);
+		/* Need to be ordered */
+		uint32_t regs[4] = {
+			EXPHI_REG,
+			EXPLO_REG,
+			GAINHI_REG,
+			GAINLO_REG
+		};
+		reg_offsets_[0] = reg_offsets_[1] = reg_offsets_[2] = reg_offsets_[3] = -1;
+		int ret = static_cast<int>(findRegs(static_cast<uint8_t *>(data),
+						    regs, reg_offsets_, 4));
+		/*
+		 * > 0 means "worked partially but parse again next time",
+		 * < 0 means "hard error".
+		 */
+		if (ret > 0)
+			try_again = true;
+		else if (ret < 0)
+			return ERROR;
+	}
+
+	for (int i = 0; i < 4; i++) {
+		if (reg_offsets_[i] == -1)
+			continue;
+
+		reg_values_[i] = static_cast<uint8_t *>(data)[reg_offsets_[i]];
+	}
+
+	/* Re-parse next time if we were unhappy in some way. */
+	reset_ = try_again;
+
+	return OK;
+}
+
+MdParser::Status MdParserImx477::GetExposureLines(unsigned int &lines)
+{
+	if (reg_offsets_[EXPHI_INDEX] == -1 || reg_offsets_[EXPLO_INDEX] == -1)
+		return NOTFOUND;
+
+	lines = reg_values_[EXPHI_INDEX] * 256 + reg_values_[EXPLO_INDEX];
+
+	return OK;
+}
+
+MdParser::Status MdParserImx477::GetGainCode(unsigned int &gain_code)
+{
+	if (reg_offsets_[GAINHI_INDEX] == -1 || reg_offsets_[GAINLO_INDEX] == -1)
+		return NOTFOUND;
+
+	gain_code = reg_values_[GAINHI_INDEX] * 256 + reg_values_[GAINLO_INDEX];
+
+	return OK;
+}