[PATCH v7 1/7] libcamera: add DmaBufAllocation::exportFrameBuffers()

[Harvey Yang]

Add a helper function exportFrameBuffers in DmaBufAllocator to make it
easier to use.

It'll be used in Virtual Pipeline Handler specifically.

Signed-off-by: Harvey Yang <chenghaoyang at chromium.org>
---
 .../libcamera/internal/dma_buf_allocator.h    | 10 +++
 src/libcamera/dma_buf_allocator.cpp           | 68 ++++++++++++++++++-
 2 files changed, 76 insertions(+), 2 deletions(-)

diff --git a/include/libcamera/internal/dma_buf_allocator.h b/include/libcamera/internal/dma_buf_allocator.h
index 36ec1696..dd2cc237 100644
--- a/include/libcamera/internal/dma_buf_allocator.h
+++ b/include/libcamera/internal/dma_buf_allocator.h
@@ -8,12 +8,16 @@
 #pragma once
 
 #include <stddef.h>
+#include <vector>
 
 #include <libcamera/base/flags.h>
 #include <libcamera/base/unique_fd.h>
 
 namespace libcamera {
 
+class FrameBuffer;
+struct StreamConfiguration;
+
 class DmaBufAllocator
 {
 public:
@@ -30,7 +34,13 @@ public:
 	bool isValid() const { return providerHandle_.isValid(); }
 	UniqueFD alloc(const char *name, std::size_t size);
 
+	int exportFrameBuffers(
+		const StreamConfiguration &config,
+		std::vector<std::unique_ptr<FrameBuffer>> *buffers);
+
 private:
+	std::unique_ptr<FrameBuffer> createBuffer(const StreamConfiguration &config);
+
 	UniqueFD allocFromHeap(const char *name, std::size_t size);
 	UniqueFD allocFromUDmaBuf(const char *name, std::size_t size);
 	UniqueFD providerHandle_;
diff --git a/src/libcamera/dma_buf_allocator.cpp b/src/libcamera/dma_buf_allocator.cpp
index c06eca7d..6b406880 100644
--- a/src/libcamera/dma_buf_allocator.cpp
+++ b/src/libcamera/dma_buf_allocator.cpp
@@ -23,6 +23,11 @@
 
 #include <libcamera/base/log.h>
 
+#include <libcamera/framebuffer.h>
+#include <libcamera/stream.h>
+
+#include "libcamera/internal/formats.h"
+
 /**
  * \file dma_buf_allocator.cpp
  * \brief dma-buf allocator
@@ -130,8 +135,8 @@ DmaBufAllocator::~DmaBufAllocator() = default;
 /* uClibc doesn't provide the file sealing API. */
 #ifndef __DOXYGEN__
 #if not HAVE_FILE_SEALS
-#define F_ADD_SEALS		1033
-#define F_SEAL_SHRINK		0x0002
+#define F_ADD_SEALS 1033
+#define F_SEAL_SHRINK 0x0002
 #endif
 #endif
 
@@ -243,4 +248,63 @@ UniqueFD DmaBufAllocator::alloc(const char *name, std::size_t size)
 		return allocFromHeap(name, size);
 }
 
+/**
+ * \brief Allocate and export buffers for \a stream from the DmaBufAllocator
+ * \param[in] config The config of the stream to allocate buffers for
+ * \param[out] buffers Array of buffers successfully allocated
+ *
+ * Allocates buffers for a stream from the DmaBufAllocator. It's a helper
+ * function that'll be used in PipelineHandler::exportFrameBuffers().
+ *
+ * \return The number of allocated buffers on success or a negative error code
+ * otherwise
+ */
+int DmaBufAllocator::exportFrameBuffers(
+	const StreamConfiguration &config,
+	std::vector<std::unique_ptr<FrameBuffer>> *buffers)
+{
+	unsigned int count = config.bufferCount;
+
+	for (unsigned i = 0; i < count; ++i) {
+		std::unique_ptr<FrameBuffer> buffer = createBuffer(config);
+		if (!buffer) {
+			LOG(DmaBufAllocator, Error) << "Unable to create buffer";
+
+			buffers->clear();
+			return -EINVAL;
+		}
+
+		buffers->push_back(std::move(buffer));
+	}
+
+	return count;
+}
+
+std::unique_ptr<FrameBuffer> DmaBufAllocator::createBuffer(
+	const StreamConfiguration &config)
+{
+	std::vector<FrameBuffer::Plane> planes;
+
+	auto info = PixelFormatInfo::info(config.pixelFormat);
+	for (size_t i = 0; i < info.planes.size(); ++i) {
+		unsigned int planeSize = info.planeSize(config.size, i);
+		if (planeSize == 0)
+			continue;
+
+		UniqueFD fd = alloc("FrameBuffer", planeSize);
+		if (!fd.isValid())
+			return nullptr;
+
+		SharedFD sharedFd(std::move(fd));
+
+		FrameBuffer::Plane plane;
+		plane.fd = sharedFd;
+		plane.offset = 0;
+		plane.length = planeSize;
+		planes.push_back(std::move(plane));
+	}
+
+	return std::make_unique<FrameBuffer>(planes);
+}
+
 } /* namespace libcamera */
-- 
2.46.0.rc1.232.g9752f9e123-goog