libcamera: software_isp: Define skeletons for IPA refactoring

Software ISP image processing algorithms are currently defined in a
simplified way, different from other libcamera pipelines.  This is not
good for several reasons:

- It makes the software ISP code harder to understand due to its
  different structuring.
- Adding more algorithms may make the code harder to understand
  generally.
- Mass libcamera code changes may not be easily applicable to software
  ISP.
- Algorithm sharing with other pipelines is not easily possible.

This patch introduces basic software ISP IPA skeletons structured
similarly to the other pipelines.  The newly added files are currently
not used or compiled and the general skeleton structures don't contain
anything particular.  It is just a preparation step for a larger
refactoring and the code will be actually used and extended as needed in
followup patches.

Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/ipa/soft.mojom

@@ -8,6 +8,10 @@ module ipa.soft;
 
 import "include/libcamera/ipa/core.mojom";
 
+struct IPAConfigInfo {
+	libcamera.ControlInfoMap sensorControls;
+};
+
 interface IPASoftInterface {
 	init(libcamera.IPASettings settings,
 	     libcamera.SharedFD fdStats,

src/ipa/simple/algorithms/algorithm.h

@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024 Red Hat, Inc.
+ *
+ * Software ISP control algorithm interface
+ */
+
+#pragma once
+
+#include <libipa/algorithm.h>
+
+#include "module.h"
+
+namespace libcamera {
+
+namespace ipa::soft {
+
+using Algorithm = libcamera::ipa::Algorithm<Module>;
+
+} /* namespace ipa::soft */
+
+} /* namespace libcamera */

src/ipa/simple/ipa_context.cpp

@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Google Inc.
+ * Copyright (C) 2024 Red Hat Inc.
+ *
+ * Software ISP IPA Context
+ */
+
+#include "ipa_context.h"
+
+/**
+ * \file ipa_context.h
+ * \brief Context and state information shared between the algorithms
+ */
+
+namespace libcamera::ipa::soft {
+
+/**
+ * \struct IPASessionConfiguration
+ * \brief Session configuration for the IPA module
+ *
+ * The session configuration contains all IPA configuration parameters that
+ * remain constant during the capture session, from IPA module start to stop.
+ * It is typically set during the configure() operation of the IPA module, but
+ * may also be updated in the start() operation.
+ */
+
+/**
+ * \struct IPAActiveState
+ * \brief The active state of the IPA algorithms
+ *
+ * The IPA is fed with the statistics generated from the latest frame processed.
+ * The statistics are then processed by the IPA algorithms to compute parameters
+ * required for the next frame capture and processing. The current state of the
+ * algorithms is reflected through the IPAActiveState to store the values most
+ * recently computed by the IPA algorithms.
+ */
+
+/**
+ * \struct IPAContext
+ * \brief Global IPA context data shared between all algorithms
+ *
+ * \var IPAContext::configuration
+ * \brief The IPA session configuration, immutable during the session
+ *
+ * \var IPAContext::frameContexts
+ * \brief Ring buffer of the IPAFrameContext(s)
+ *
+ * \var IPAContext::activeState
+ * \brief The current state of IPA algorithms
+ */
+
+} /* namespace libcamera::ipa::soft */

src/ipa/simple/ipa_context.h

@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024 Red Hat, Inc.
+ *
+ * Simple pipeline IPA Context
+ */
+
+#pragma once
+
+#include <libipa/fc_queue.h>
+
+namespace libcamera {
+
+namespace ipa::soft {
+
+struct IPASessionConfiguration {
+};
+
+struct IPAActiveState {
+};
+
+struct IPAFrameContext : public FrameContext {
+};
+
+struct IPAContext {
+	IPASessionConfiguration configuration;
+	IPAActiveState activeState;
+	FCQueue<IPAFrameContext> frameContexts;
+};
+
+} /* namespace ipa::soft */
+
+} /* namespace libcamera */

src/ipa/simple/meson.build

@@ -3,6 +3,7 @@
 ipa_name = 'ipa_soft_simple'
 
 soft_simple_sources = files([
+    'ipa_context.cpp',
     'soft_simple.cpp',
     'black_level.cpp',
 ])

src/ipa/simple/module.h

@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024 Red Hat, Inc.
+ *
+ * Software ISP IPA Module
+ */
+
+#pragma once
+
+#include <libcamera/controls.h>
+
+#include <libcamera/ipa/soft_ipa_interface.h>
+
+#include "libcamera/internal/software_isp/debayer_params.h"
+#include "libcamera/internal/software_isp/swisp_stats.h"
+
+#include <libipa/module.h>
+
+#include "ipa_context.h"
+
+namespace libcamera {
+
+namespace ipa::soft {
+
+using Module = ipa::Module<IPAContext, IPAFrameContext, IPAConfigInfo,
+			   DebayerParams, SwIspStats>;
+
+} /* namespace ipa::soft */
+
+} /* namespace libcamera */