libcamera: ipa_manager: implement class for managing IPA modules

IPAManager is a class that will search in given directories for IPA
modules, and will load them into a list. It also provides an interface
for pipeline handlers to acquire an IPA.

A meson build file for the IPAs is added, which also specifies a
hard-coded path for where to load the IPAs from in the installation
directory. More paths can be specified with the environment variable
LIBCAMERA_IPA_MODULE_PATH, with the same syntax as the regular PATH
environment variable. Make the test framework set this environment
variable.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/libcamera/include/ipa_manager.h

@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * ipa_manager.h - Image Processing Algorithm module manager
+ */
+#ifndef __LIBCAMERA_IPA_MANAGER_H__
+#define __LIBCAMERA_IPA_MANAGER_H__
+
+#include <vector>
+
+#include <libcamera/ipa/ipa_interface.h>
+#include <libcamera/ipa/ipa_module_info.h>
+
+#include "ipa_module.h"
+#include "pipeline_handler.h"
+
+namespace libcamera {
+
+class IPAManager
+{
+public:
+	static IPAManager *instance();
+
+	std::unique_ptr<IPAInterface> createIPA(PipelineHandler *pipe,
+						uint32_t maxVersion,
+						uint32_t minVersion);
+
+private:
+	std::vector<IPAModule *> modules_;
+
+	IPAManager();
+	~IPAManager();
+
+	int addDir(const char *libDir);
+};
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_IPA_MANAGER_H__ */