libcamera: Add new libcamera source

Provide the integration of a libcamera source within uvc-gadget.
This adds C++ support to the project and adds libcamera as an
optional external dependency.

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>

2 files changed, 481 insertions, 0 deletions

diff --git a/lib/libcamera-source.cpp b/lib/libcamera-source.cpp
new file mode 100644
index 0000000..c53c915
--- /dev/null
+++ b/lib/libcamera-source.cpp
@@ -0,0 +1,476 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * libcamera source
+ *
+ * Copyright (C) 2022 Ideas on Board Oy
+ *
+ * Contact: Daniel Scally <dan.scally@ideasonboard.com>
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <iostream>
+#include <memory.h>
+#include <queue>
+#include <stdlib.h>
+#include <string>
+#include <string.h>
+#include <unistd.h>
+
+#include <libcamera/libcamera.h>
+#include <linux/videodev2.h>
+
+extern "C" {
+#include "events.h"
+#include "libcamera-source.h"
+#include "tools.h"
+#include "video-buffers.h"
+}
+
+using namespace libcamera;
+
+#define to_libcamera_source(s) container_of(s, struct libcamera_source, src)
+
+struct libcamera_source {
+	struct video_source src;
+
+	std::unique_ptr<CameraManager> cm;
+	std::unique_ptr<CameraConfiguration> config;
+	std::shared_ptr<Camera> camera;
+	ControlList controls;
+
+	FrameBufferAllocator *allocator;
+	std::vector<std::unique_ptr<Request>> requests;
+	std::queue<Request *> completed_requests;
+	int pfds[2];
+
+	struct video_buffer_set buffers;
+
+	void requestComplete(Request *request);
+};
+
+void libcamera_source::requestComplete(Request *request)
+{
+	if (request->status() == Request::RequestCancelled)
+		return;
+
+	completed_requests.push(request);
+
+	/*
+	 * We want to hand off to the event loop to do any further processing,
+	 * which we can achieve by simply writing to the end of the pipe since
+	 * the loop is polling the other end. Once the event loop picks up this
+	 * write it will run libcamera_source_video_process().
+	 */
+	write(pfds[1], "x", 1);
+};
+
+static void libcamera_source_video_process(void *d)
+{
+	struct libcamera_source *src = (struct libcamera_source *)d;
+	struct video_buffer buffer;
+	Request *request;
+
+	if (src->completed_requests.empty())
+		return;
+
+	request = src->completed_requests.front();
+	src->completed_requests.pop();
+
+	/* We have only a single buffer per request, so just pick the first */
+	FrameBuffer *framebuf = request->buffers().begin()->second;
+
+	buffer.index = request->cookie();
+
+	/* TODO: Correct this for formats libcamera treats as multiplanar */
+	buffer.size = framebuf->planes()[0].length;
+	buffer.mem = NULL;
+	buffer.bytesused = framebuf->metadata().planes()[0].bytesused;
+	buffer.timestamp.tv_usec = framebuf->metadata().timestamp;
+	buffer.error = false;
+
+	src->src.handler(src->src.handler_data, &src->src, &buffer);
+}
+
+static void libcamera_source_destroy(struct video_source *s)
+{
+	struct libcamera_source *src = to_libcamera_source(s);
+
+	src->camera->requestCompleted.disconnect(src);
+
+	/* Closing the event notification file descriptors */
+	close(src->pfds[0]);
+	close(src->pfds[1]);
+
+	src->camera->release();
+	src->camera.reset();
+	src->cm->stop();
+	delete src;
+}
+
+static int libcamera_source_set_format(struct video_source *s,
+				       struct v4l2_pix_format *fmt)
+{
+	struct libcamera_source *src = to_libcamera_source(s);
+	StreamConfiguration &streamConfig = src->config->at(0);
+
+	streamConfig.size.width = fmt->width;
+	streamConfig.size.height = fmt->height;
+	streamConfig.pixelFormat = PixelFormat(fmt->pixelformat);
+
+	src->config->validate();
+
+	if (fmt->pixelformat != streamConfig.pixelFormat.fourcc())
+		std::cerr << "Warning: set_format: Requested format unavailable" << std::endl;
+
+	std::cout << "setting format to " << streamConfig.toString() << std::endl;
+
+	/*
+	 * No .configure() call at this stage, because we need to pick up the
+	 * number of buffers to use later on so we'd need to call it then too.
+	 */
+
+	fmt->width = streamConfig.size.width;
+	fmt->height = streamConfig.size.height;
+	fmt->pixelformat = streamConfig.pixelFormat.fourcc();
+	fmt->field = V4L2_FIELD_ANY;
+
+	/* TODO: Can we use libcamera helpers to get image size / stride? */
+	fmt->sizeimage = fmt->width * fmt->height * 2;
+
+	return 0;
+}
+
+static int libcamera_source_set_frame_rate(struct video_source *s, unsigned int fps)
+{
+	struct libcamera_source *src = to_libcamera_source(s);
+	int64_t frame_time = 1000000 / fps;
+
+	src->controls.set(controls::FrameDurationLimits,
+			  Span<const int64_t, 2>({ frame_time, frame_time }));
+
+	return 0;
+}
+
+static int libcamera_source_alloc_buffers(struct video_source *s, unsigned int nbufs)
+{
+	struct libcamera_source *src = to_libcamera_source(s);
+	StreamConfiguration &streamConfig = src->config->at(0);
+	int ret;
+
+	streamConfig.bufferCount = nbufs;
+	ret = src->camera->configure(src->config.get());
+	if (ret) {
+		std::cerr << "failed to configure the camera" << std::endl;
+		return ret;
+	}
+
+	Stream *stream = src->config->at(0).stream();
+	FrameBufferAllocator *allocator;
+
+	allocator = new FrameBufferAllocator(src->camera);
+
+	ret = allocator->allocate(stream);
+	if (ret < 0) {
+		std::cerr << "failed to allocate buffers" << std::endl;
+		return ret;
+	}
+
+	src->allocator = allocator;
+
+	const std::vector<std::unique_ptr<FrameBuffer>> &buffers = allocator->buffers(stream);
+	src->buffers.nbufs = buffers.size();
+
+	src->buffers.buffers = (video_buffer *)calloc(src->buffers.nbufs, sizeof(*src->buffers.buffers));
+	if (!src->buffers.buffers) {
+		std::cerr << "failed to allocate buffers" << std::endl;
+		return -ENOMEM;
+	}
+
+	for (unsigned int i = 0; i < buffers.size(); ++i) {
+		src->buffers.buffers[i].index = i;
+		src->buffers.buffers[i].dmabuf = -1;
+	}
+
+	return ret;
+}
+
+static int libcamera_source_export_buffers(struct video_source *s,
+					   struct video_buffer_set **bufs)
+{
+	struct libcamera_source *src = to_libcamera_source(s);
+	Stream *stream = src->config->at(0).stream();
+	const std::vector<std::unique_ptr<FrameBuffer>> &buffers = src->allocator->buffers(stream);
+	struct video_buffer_set *vid_buf_set;
+	unsigned int i;
+
+	for (i = 0; i < buffers.size(); i++) {
+		const std::unique_ptr<FrameBuffer> &buffer = buffers[i];
+
+		src->buffers.buffers[i].size = buffer->planes()[0].length;
+		src->buffers.buffers[i].dmabuf = buffer->planes()[0].fd.get();
+	}
+
+	vid_buf_set = video_buffer_set_new(buffers.size());
+	if (!vid_buf_set)
+		return -ENOMEM;
+
+	for (i = 0; i < src->buffers.nbufs; ++i) {
+		struct video_buffer *buffer = &src->buffers.buffers[i];
+
+		vid_buf_set->buffers[i].size = buffer->size;
+		vid_buf_set->buffers[i].dmabuf = buffer->dmabuf;
+	}
+
+	*bufs = vid_buf_set;
+
+	return 0;
+}
+
+static int libcamera_source_free_buffers(struct video_source *s)
+{
+	struct libcamera_source *src = to_libcamera_source(s);
+	Stream *stream = src->config->at(0).stream();
+
+	src->allocator->free(stream);
+	delete src->allocator;
+	free(src->buffers.buffers);
+
+	return 0;
+}
+
+static int libcamera_source_stream_on(struct video_source *s)
+{
+	struct libcamera_source *src = to_libcamera_source(s);
+	Stream *stream = src->config->at(0).stream();
+	int ret;
+
+	const std::vector<std::unique_ptr<FrameBuffer>> &buffers = src->allocator->buffers(stream);
+
+	for (unsigned int i = 0; i < buffers.size(); ++i) {
+		std::unique_ptr<Request> request = src->camera->createRequest(i);
+		if (!request) {
+			std::cerr << "failed to create request" << std::endl;
+			return -ENOMEM;
+		}
+
+		const std::unique_ptr<FrameBuffer> &buffer = buffers[i];
+		ret = request->addBuffer(stream, buffer.get());
+		if (ret < 0) {
+			std::cerr << "failed to set buffer for request" << std::endl;
+			return ret;
+		}
+
+		src->requests.push_back(std::move(request));
+	}
+
+	ret = src->camera->start(&src->controls);
+	if (ret) {
+		std::cerr << "failed to start camera" << std::endl;
+		return ret;
+	}
+
+	for (std::unique_ptr<Request> &request : src->requests) {
+		ret = src->camera->queueRequest(request.get());
+		if (ret) {
+			std::cerr << "failed to queue request" << std::endl;
+			src->camera->stop();
+			return ret;
+		}
+	}
+
+	/*
+	 * Given our event handling code is designed for V4L2 file descriptors
+	 * and lacks a way to trigger an event manually, we're using a pipe so
+	 * that we can watch the read end and write to the other end when
+	 * requestComplete() is ran.
+	 */
+	events_watch_fd(src->src.events, src->pfds[0], EVENT_READ,
+			libcamera_source_video_process, src);
+
+	return 0;
+}
+
+static int libcamera_source_stream_off(struct video_source *s)
+{
+	struct libcamera_source *src = to_libcamera_source(s);
+
+	src->camera->stop();
+	events_unwatch_fd(src->src.events, src->pfds[0], EVENT_READ);
+	src->requests.clear();
+
+	while (!src->completed_requests.empty())
+		src->completed_requests.pop();
+
+	return 0;
+}
+
+static int libcamera_source_queue_buffer(struct video_source *s,
+					 struct video_buffer *buf)
+{
+	struct libcamera_source *src = to_libcamera_source(s);
+
+	for (std::unique_ptr<Request> &r : src->requests) {
+		if (r->cookie() == buf->index) {
+			r->reuse(Request::ReuseBuffers);
+			src->camera->queueRequest(r.get());
+
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static const struct video_source_ops libcamera_source_ops = {
+	.destroy = libcamera_source_destroy,
+	.set_format = libcamera_source_set_format,
+	.set_frame_rate = libcamera_source_set_frame_rate,
+	.alloc_buffers = libcamera_source_alloc_buffers,
+	.export_buffers = libcamera_source_export_buffers,
+	.free_buffers = libcamera_source_free_buffers,
+	.stream_on = libcamera_source_stream_on,
+	.stream_off = libcamera_source_stream_off,
+	.queue_buffer = libcamera_source_queue_buffer,
+	.fill_buffer = NULL,
+};
+
+std::string cameraName(Camera *camera)
+{
+	const ControlList &props = camera->properties();
+	std::string name;
+
+	const auto &location = props.get(properties::Location);
+	if (location) {
+		switch (*location) {
+		case properties::CameraLocationFront:
+			name = "Internal Front Camera";
+			break;
+		case properties::CameraLocationBack:
+			name = "Internal back camera";
+			break;
+		case properties::CameraLocationExternal:
+			name = "External camera";
+			const auto &model = props.get(properties::Model);
+			if (model)
+				name = *model;
+			break;
+		}
+	}
+	name += " (" + camera->id() + ")";
+
+	return name;
+}
+
+struct video_source *libcamera_source_create(const char *devname)
+{
+	struct libcamera_source *src;
+	int ret;
+
+	if (!devname) {
+		std::cerr << "No camera identifier was passed" << std::endl;
+		return NULL;
+	}
+
+	src = new libcamera_source;
+
+	/*
+	 * Event handling in libuvcgadget currently depends on select(), but
+	 * unlike a V4L2 devnode there's no file descriptor for completed
+	 * libcamera Requests. We'll spoof the events using a pipe for now,
+	 * but...
+	 *
+	 * TODO: Replace event handling with libevent
+	 */
+
+	ret = pipe2(src->pfds, O_NONBLOCK);
+	if (ret) {
+		std::cerr << "failed to create pipe" << std::endl;
+		goto err_free_src;
+	}
+
+	src->src.ops = &libcamera_source_ops;
+	src->cm = std::make_unique<CameraManager>();
+	src->cm->start();
+
+	if (src->cm->cameras().empty()) {
+		std::cout << "No cameras were identified on the system" << std::endl;
+		goto err_close_pipe;
+	}
+
+	/* TODO: make a separate way to list libcamera cameras */
+	for (auto const &camera : src->cm->cameras())
+		printf("- %s\n", cameraName(camera.get()).c_str());
+
+	/*
+	 * Camera selection is by ID or index. Camera ID's start with a slash.
+	 * If the first character is a digit, assume we're indexing, otherwise
+	 * treat it as an ID.
+	 */
+	if (std::isdigit(devname[0])) {
+		unsigned long index = std::atoi(devname);
+
+		if (index >= src->cm->cameras().size()) {
+			std::cerr << "No camera at index " << index << std::endl;
+			goto err_close_pipe;
+		}
+
+		src->camera = src->cm->cameras()[index];
+	} else {
+		src->camera = src->cm->get(std::string(devname));
+		if (!src->camera) {
+			std::cerr << "found no camera matching " << devname << std::endl;
+			goto err_close_pipe;
+		}
+	}
+
+	ret = src->camera->acquire();
+	if (ret) {
+		fprintf(stderr, "failed to acquire camera\n");
+		goto err_close_pipe;
+	}
+
+	std::cout << "Using camera " << cameraName(src->camera.get()) << std::endl;
+
+	src->config =
+		src->camera->generateConfiguration( { StreamRole::VideoRecording });
+	if (!src->config) {
+		std::cerr << "failed to generate camera config" << std::endl;
+		goto err_release_camera;
+	}
+
+	src->camera->requestCompleted.connect(src, &libcamera_source::requestComplete);
+
+	{
+		/*
+		 * We enable AutoFocus by default if it's supported by the camera.
+		 * Keep the infoMap scoped to calm the compiler worrying about
+		 * jumping over the reference with the gotos.
+		 */
+		const ControlInfoMap &infoMap = src->camera->controls();
+		if (infoMap.find(&controls::AfMode) != infoMap.end()) {
+			std::cout << "Enabling continuous auto-focus" << std::endl;
+			src->controls.set(controls::AfMode, controls::AfModeContinuous);
+		}
+	}
+
+	return &src->src;
+
+err_release_camera:
+	src->camera->release();
+err_close_pipe:
+	close(src->pfds[0]);
+	close(src->pfds[1]);
+	src->cm->stop();
+err_free_src:
+	delete src;
+
+	return NULL;
+}
+
+void libcamera_source_init(struct video_source *s, struct events *events)
+{
+	struct libcamera_source *src = to_libcamera_source(s);
+
+	src->src.events = events;
+}
diff --git a/lib/meson.build b/lib/meson.build
index 680be1c..0931eef 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -15,8 +15,13 @@ libuvcgadget_sources = files([
   'video-source.c',
 ])
 
+if libcamera.found()
+  libuvcgadget_sources += files(['libcamera-source.cpp'])
+endif
+
 libuvcgadget = shared_library('uvcgadget',
                               libuvcgadget_sources,
+                              dependencies : libcamera,
                               version : uvc_gadget_version,
                               install : true,
                               include_directories : includes)