ipa: Switch to the plain C API

Switch IPA communication to the plain C API. As the IPAInterface class
is easier to use for pipeline handlers than a plain C API, retain it and
add an IPAContextWrapper that translate between the C++ and the C APIs.

On the IPA module side usage of IPAInterface may be desired for IPAs
implemented in C++ that want to link to libcamera. For those IPAs, a new
IPAInterfaceWrapper helper class is introduced to wrap the IPAInterface
implemented internally by the IPA module into an ipa_context,
ipa_context_ops and ipa_callback_ops.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

8 files changed, 351 insertions, 18 deletions

diff --git a/src/libcamera/include/ipa_context_wrapper.h b/src/libcamera/include/ipa_context_wrapper.h
new file mode 100644
index 00000000..06088821
--- /dev/null
+++ b/src/libcamera/include/ipa_context_wrapper.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * ipa_context_wrapper.h - Image Processing Algorithm context wrapper
+ */
+#ifndef __LIBCAMERA_IPA_CONTEXT_WRAPPER_H__
+#define __LIBCAMERA_IPA_CONTEXT_WRAPPER_H__
+
+#include <ipa/ipa_interface.h>
+
+#include "control_serializer.h"
+
+namespace libcamera {
+
+class IPAContextWrapper final : public IPAInterface
+{
+public:
+	IPAContextWrapper(struct ipa_context *context);
+	~IPAContextWrapper();
+
+	int init() override;
+	void configure(const std::map<unsigned int, IPAStream> &streamConfig,
+		       const std::map<unsigned int, const ControlInfoMap &> &entityControls) override;
+
+	void mapBuffers(const std::vector<IPABuffer> &buffers) override;
+	void unmapBuffers(const std::vector<unsigned int> &ids) override;
+
+	virtual void processEvent(const IPAOperationData &data) override;
+
+private:
+	static void queue_frame_action(void *ctx, unsigned int frame,
+				       struct ipa_operation_data &data);
+	static const struct ipa_callback_ops callbacks_;
+
+	struct ipa_context *ctx_;
+
+	ControlSerializer serializer_;
+};
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_IPA_CONTEXT_WRAPPER_H__ */
diff --git a/src/libcamera/include/ipa_module.h b/src/libcamera/include/ipa_module.h
index 97737587..2028b76a 100644
--- a/src/libcamera/include/ipa_module.h
+++ b/src/libcamera/include/ipa_module.h
@@ -7,7 +7,6 @@
 #ifndef __LIBCAMERA_IPA_MODULE_H__
 #define __LIBCAMERA_IPA_MODULE_H__
 
-#include <memory>
 #include <string>
 
 #include <ipa/ipa_interface.h>
@@ -30,7 +29,7 @@ public:
 
 	bool load();
 
-	std::unique_ptr<IPAInterface> createInstance();
+	struct ipa_context *createContext();
 
 	bool match(PipelineHandler *pipe,
 		   uint32_t minVersion, uint32_t maxVersion) const;
@@ -45,7 +44,7 @@ private:
 	bool loaded_;
 
 	void *dlHandle_;
-	typedef IPAInterface *(*IPAIntfFactory)(void);
+	typedef struct ipa_context *(*IPAIntfFactory)(void);
 	IPAIntfFactory ipaCreate_;
 
 	int loadIPAModuleInfo();
diff --git a/src/libcamera/include/meson.build b/src/libcamera/include/meson.build
index 697294f4..17e2bed9 100644
--- a/src/libcamera/include/meson.build
+++ b/src/libcamera/include/meson.build
@@ -9,6 +9,7 @@ libcamera_headers = files([
     'device_enumerator_udev.h',
     'event_dispatcher_poll.h',
     'formats.h',
+    'ipa_context_wrapper.h',
     'ipa_manager.h',
     'ipa_module.h',
     'ipa_proxy.h',
diff --git a/src/libcamera/ipa_context_wrapper.cpp b/src/libcamera/ipa_context_wrapper.cpp
new file mode 100644
index 00000000..5b1f5972
--- /dev/null
+++ b/src/libcamera/ipa_context_wrapper.cpp
@@ -0,0 +1,221 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * ipa_context_wrapper.cpp - Image Processing Algorithm context wrapper
+ */
+
+#include "ipa_context_wrapper.h"
+
+#include <vector>
+
+#include <libcamera/controls.h>
+
+#include "byte_stream_buffer.h"
+
+/**
+ * \file ipa_context_wrapper.h
+ * \brief Image Processing Algorithm context wrapper
+ */
+
+namespace libcamera {
+
+/**
+ * \class IPAContextWrapper
+ * \brief Wrap an ipa_context and expose it as an IPAInterface
+ *
+ * The IPAContextWrapper class wraps an ipa_context, provided by an IPA module, and
+ * exposes an IPAInterface. This mechanism is used for IPAs that are not
+ * isolated in a separate process to allow direct calls from pipeline handler
+ * using the IPAInterface API instead of the lower-level ipa_context API.
+ *
+ * The IPAInterface methods are converted to the ipa_context API by translating
+ * all C++ arguments into plain C structures or byte arrays that contain no
+ * pointer, as required by the ipa_context API.
+ */
+
+/**
+ * \brief Construct an IPAContextWrapper instance that wraps the \a context
+ * \param[in] context The IPA module context
+ *
+ * Ownership of the \a context is passed to the IPAContextWrapper. The context remains
+ * valid for the whole lifetime of the wrapper and is destroyed automatically
+ * with it.
+ */
+IPAContextWrapper::IPAContextWrapper(struct ipa_context *context)
+	: ctx_(context)
+{
+	if (!ctx_)
+		return;
+
+	ctx_->ops->register_callbacks(ctx_, &IPAContextWrapper::callbacks_,
+				      this);
+}
+
+IPAContextWrapper::~IPAContextWrapper()
+{
+	if (!ctx_)
+		return;
+
+	ctx_->ops->destroy(ctx_);
+}
+
+int IPAContextWrapper::init()
+{
+	if (!ctx_)
+		return 0;
+
+	ctx_->ops->init(ctx_);
+
+	return 0;
+}
+
+void IPAContextWrapper::configure(const std::map<unsigned int, IPAStream> &streamConfig,
+				  const std::map<unsigned int, const ControlInfoMap &> &entityControls)
+{
+	if (!ctx_)
+		return;
+
+	serializer_.reset();
+
+	/* Translate the IPA stream configurations map. */
+	struct ipa_stream c_streams[streamConfig.size()];
+
+	unsigned int i = 0;
+	for (const auto &stream : streamConfig) {
+		struct ipa_stream *c_stream = &c_streams[i];
+		unsigned int id = stream.first;
+		const IPAStream &ipaStream = stream.second;
+
+		c_stream->id = id;
+		c_stream->pixel_format = ipaStream.pixelFormat;
+		c_stream->width = ipaStream.size.width;
+		c_stream->height = ipaStream.size.height;
+
+		++i;
+	}
+
+	/* Translate the IPA entity controls map. */
+	struct ipa_control_info_map c_info_maps[entityControls.size()];
+	std::vector<std::vector<uint8_t>> data(entityControls.size());
+
+	i = 0;
+	for (const auto &info : entityControls) {
+		struct ipa_control_info_map &c_info_map = c_info_maps[i];
+		unsigned int id = info.first;
+		const ControlInfoMap &infoMap = info.second;
+
+		size_t infoMapSize = serializer_.binarySize(infoMap);
+		data[i].resize(infoMapSize);
+		ByteStreamBuffer byteStream(data[i].data(), data[i].size());
+		serializer_.serialize(infoMap, byteStream);
+
+		c_info_map.id = id;
+		c_info_map.data = byteStream.base();
+		c_info_map.size = byteStream.size();
+
+		++i;
+	}
+
+	ctx_->ops->configure(ctx_, c_streams, streamConfig.size(),
+			     c_info_maps, entityControls.size());
+}
+
+void IPAContextWrapper::mapBuffers(const std::vector<IPABuffer> &buffers)
+{
+	if (!ctx_)
+		return;
+
+	struct ipa_buffer c_buffers[buffers.size()];
+
+	for (unsigned int i = 0; i < buffers.size(); ++i) {
+		struct ipa_buffer &c_buffer = c_buffers[i];
+		const IPABuffer &buffer = buffers[i];
+		const std::vector<Plane> &planes = buffer.memory.planes();
+
+		c_buffer.id = buffer.id;
+		c_buffer.num_planes = planes.size();
+
+		for (unsigned int j = 0; j < planes.size(); ++j) {
+			const Plane &plane = planes[j];
+			c_buffer.planes[j].dmabuf = plane.dmabuf();
+			c_buffer.planes[j].length = plane.length();
+		}
+	}
+
+	ctx_->ops->map_buffers(ctx_, c_buffers, buffers.size());
+}
+
+void IPAContextWrapper::unmapBuffers(const std::vector<unsigned int> &ids)
+{
+	if (!ctx_)
+		return;
+
+	ctx_->ops->unmap_buffers(ctx_, ids.data(), ids.size());
+}
+
+void IPAContextWrapper::processEvent(const IPAOperationData &data)
+{
+	if (!ctx_)
+		return;
+
+	struct ipa_operation_data c_data;
+	c_data.operation = data.operation;
+	c_data.data = data.data.data();
+	c_data.num_data = data.data.size();
+
+	struct ipa_control_list control_lists[data.controls.size()];
+	c_data.lists = control_lists;
+	c_data.num_lists = data.controls.size();
+
+	std::size_t listsSize = 0;
+	for (const auto &list : data.controls)
+		listsSize += serializer_.binarySize(list);
+
+	std::vector<uint8_t> binaryData(listsSize);
+	ByteStreamBuffer byteStreamBuffer(binaryData.data(), listsSize);
+
+	unsigned int i = 0;
+	for (const auto &list : data.controls) {
+		struct ipa_control_list &c_list = control_lists[i];
+		c_list.size = serializer_.binarySize(list);
+		ByteStreamBuffer b = byteStreamBuffer.carveOut(c_list.size);
+
+		serializer_.serialize(list, b);
+
+		c_list.data = b.base();
+	}
+
+	ctx_->ops->process_event(ctx_, &c_data);
+}
+
+void IPAContextWrapper::queue_frame_action(void *ctx, unsigned int frame,
+					   struct ipa_operation_data &data)
+{
+	IPAContextWrapper *_this = static_cast<IPAContextWrapper *>(ctx);
+	IPAOperationData opData;
+
+	opData.operation = data.operation;
+	for (unsigned int i = 0; i < data.num_data; ++i)
+		opData.data.push_back(data.data[i]);
+
+	for (unsigned int i = 0; i < data.num_lists; ++i) {
+		const struct ipa_control_list &c_list = data.lists[i];
+		ByteStreamBuffer b(c_list.data, c_list.size);
+		opData.controls.push_back(_this->serializer_.deserialize<ControlList>(b));
+	}
+
+	_this->queueFrameAction.emit(frame, opData);
+}
+
+#ifndef __DOXYGEN__
+/*
+ * This construct confuses Doygen and makes it believe that all members of the
+ * operations is a member of IPAInterfaceWrapper. It must thus be hidden.
+ */
+const struct ipa_callback_ops IPAContextWrapper::callbacks_ = {
+	.queue_frame_action = &IPAContextWrapper::queue_frame_action,
+};
+#endif
+
+} /* namespace libcamera */
diff --git a/src/libcamera/ipa_manager.cpp b/src/libcamera/ipa_manager.cpp
index f3180c07..90eef12d 100644
--- a/src/libcamera/ipa_manager.cpp
+++ b/src/libcamera/ipa_manager.cpp
@@ -12,6 +12,7 @@
 #include <string.h>
 #include <sys/types.h>
 
+#include "ipa_context_wrapper.h"
 #include "ipa_module.h"
 #include "ipa_proxy.h"
 #include "log.h"
@@ -30,6 +31,66 @@ LOG_DEFINE_CATEGORY(IPAManager)
 /**
  * \class IPAManager
  * \brief Manager for IPA modules
+ *
+ * The IPA module manager discovers IPA modules from disk, queries and loads
+ * them, and creates IPA contexts. It supports isolation of the modules in a
+ * separate process with IPC communication and offers a unified IPAInterface
+ * view of the IPA contexts to pipeline handlers regardless of whether the
+ * modules are isolated or loaded in the same process.
+ *
+ * Module isolation is based on the module licence. Open-source modules are
+ * loaded without isolation, while closed-source module are forcefully isolated.
+ * The isolation mechanism ensures that no code from a closed-source module is
+ * ever run in the libcamera process.
+ *
+ * To create an IPA context, pipeline handlers call the IPAManager::ipaCreate()
+ * method. For a directly loaded module, the manager calls the module's
+ * ipaCreate() function directly and wraps the returned context in an
+ * IPAContextWrapper that exposes an IPAInterface.
+ *
+ * ~~~~
+ * +---------------+
+ * |   Pipeline    |
+ * |    Handler    |
+ * +---------------+
+ *         |
+ *         v
+ * +---------------+                   +---------------+
+ * |      IPA      |                   |  Open Source  |
+ * |   Interface   |                   |  IPA Module   |
+ * | - - - - - - - |                   | - - - - - - - |
+ * |  IPA Context  |  ipa_context_ops  |  ipa_context  |
+ * |    Wrapper    | ----------------> |               |
+ * +---------------+                   +---------------+
+ * ~~~~
+ *
+ * For an isolated module, the manager instantiates an IPAProxy which spawns a
+ * new process for an IPA proxy worker. The worker loads the IPA module and
+ * creates the IPA context. The IPAProxy alse exposes an IPAInterface.
+ *
+ * ~~~~
+ * +---------------+                   +---------------+
+ * |   Pipeline    |                   | Closed Source |
+ * |    Handler    |                   |  IPA Module   |
+ * +---------------+                   | - - - - - - - |
+ *         |                           |  ipa_context  |
+ *         v                           |               |
+ * +---------------+                   +---------------+
+ * |      IPA      |           ipa_context_ops ^
+ * |   Interface   |                           |
+ * | - - - - - - - |                   +---------------+
+ * |   IPA Proxy   |     operations    |   IPA Proxy   |
+ * |               | ----------------> |    Worker     |
+ * +---------------+      over IPC     +---------------+
+ * ~~~~
+ *
+ * The IPAInterface implemented by the IPAContextWrapper or IPAProxy is
+ * returned to the pipeline handler, and all interactions with the IPA context
+ * go the same interface regardless of process isolation.
+ *
+ * In all cases the data passed to the IPAInterface methods is serialized to
+ * Plain Old Data, either for the purpose of passing it to the IPA context
+ * plain C API, or to transmit the data to the isolated process through IPC.
  */
 
 IPAManager::IPAManager()
@@ -199,7 +260,11 @@ std::unique_ptr<IPAInterface> IPAManager::createIPA(PipelineHandler *pipe,
 	if (!m->load())
 		return nullptr;
 
-	return m->createInstance();
+	struct ipa_context *ctx = m->createContext();
+	if (!ctx)
+		return nullptr;
+
+	return utils::make_unique<IPAContextWrapper>(ctx);
 }
 
 } /* namespace libcamera */
diff --git a/src/libcamera/ipa_module.cpp b/src/libcamera/ipa_module.cpp
index 99d308ef..2c355ea8 100644
--- a/src/libcamera/ipa_module.cpp
+++ b/src/libcamera/ipa_module.cpp
@@ -385,13 +385,13 @@ const std::string &IPAModule::path() const
 /**
  * \brief Load the IPA implementation factory from the shared object
  *
- * The IPA module shared object implements an IPAInterface class to be used
+ * The IPA module shared object implements an ipa_context object to be used
  * by pipeline handlers. This method loads the factory function from the
- * shared object. Later, createInstance() can be called to instantiate the
- * IPAInterface.
+ * shared object. Later, createContext() can be called to instantiate the
+ * ipa_context.
  *
  * This method only needs to be called successfully once, after which
- * createInstance() can be called as many times as IPAInterface instances are
+ * createContext() can be called as many times as ipa_context instances are
  * needed.
  *
  * Calling this function on an invalid module (as returned by isValid()) is
@@ -433,24 +433,25 @@ bool IPAModule::load()
 }
 
 /**
- * \brief Instantiate an IPAInterface
+ * \brief Instantiate an IPA context
  *
- * After loading the IPA module with load(), this method creates an
- * instance of the IPA module interface.
+ * After loading the IPA module with load(), this method creates an instance of
+ * the IPA module context. Ownership of the context is passed to the caller, and
+ * the context shall be destroyed by calling the \ref ipa_context_ops::destroy
+ * "ipa_context::ops::destroy()" function.
  *
  * Calling this function on a module that has not yet been loaded, or an
  * invalid module (as returned by load() and isValid(), respectively) is
  * an error.
  *
- * \return The IPA implementation as a new IPAInterface instance on success,
- * or nullptr on error
+ * \return The IPA context on success, or nullptr on error
  */
-std::unique_ptr<IPAInterface> IPAModule::createInstance()
+struct ipa_context *IPAModule::createContext()
 {
 	if (!valid_ || !loaded_)
 		return nullptr;
 
-	return std::unique_ptr<IPAInterface>(ipaCreate_());
+	return ipaCreate_();
 }
 
 /**
diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
index 59cf5825..c4f965bd 100644
--- a/src/libcamera/meson.build
+++ b/src/libcamera/meson.build
@@ -16,6 +16,7 @@ libcamera_sources = files([
     'event_notifier.cpp',
     'formats.cpp',
     'geometry.cpp',
+    'ipa_context_wrapper.cpp',
     'ipa_controls.cpp',
     'ipa_interface.cpp',
     'ipa_manager.cpp',
diff --git a/src/libcamera/proxy/worker/ipa_proxy_linux_worker.cpp b/src/libcamera/proxy/worker/ipa_proxy_linux_worker.cpp
index a10761e5..07380c16 100644
--- a/src/libcamera/proxy/worker/ipa_proxy_linux_worker.cpp
+++ b/src/libcamera/proxy/worker/ipa_proxy_linux_worker.cpp
@@ -72,9 +72,9 @@ int main(int argc, char **argv)
 	}
 	socket.readyRead.connect(&readyRead);
 
-	std::unique_ptr<IPAInterface> ipa = ipam->createInstance();
-	if (!ipa) {
-		LOG(IPAProxyLinuxWorker, Error) << "Failed to create IPA interface";
+	struct ipa_context *ipac = ipam->createContext();
+	if (!ipac) {
+		LOG(IPAProxyLinuxWorker, Error) << "Failed to create IPA context";
 		return EXIT_FAILURE;
 	}
 
@@ -85,5 +85,7 @@ int main(int argc, char **argv)
 	while (1)
 		dispatcher->processEvents();
 
+	ipac->ops->destroy(ipac);
+
 	return 0;
 }