/* * videobuf2-dma-contig.c - DMA contig memory allocator for videobuf2 * * Copyright (C) 2010 Samsung Electronics * * Author: Pawel Osciak <[email protected]> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation. */ #include <linux/dma-buf.h> #include <linux/module.h> #include <linux/refcount.h> #include <linux/scatterlist.h> #include <linux/sched.h> #include <linux/slab.h> #include <linux/dma-mapping.h> #include <linux/highmem.h> #include <media/videobuf2-v4l2.h> #include <media/videobuf2-dma-contig.h> #include <media/videobuf2-memops.h> struct vb2_dc_buf { … }; /*********************************************/ /* scatterlist table functions */ /*********************************************/ static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt) { … } /*********************************************/ /* callbacks for all buffers */ /*********************************************/ static void *vb2_dc_cookie(struct vb2_buffer *vb, void *buf_priv) { … } /* * This function may fail if: * * - dma_buf_vmap() fails * E.g. due to lack of virtual mapping address space, or due to * dmabuf->ops misconfiguration. * * - dma_vmap_noncontiguous() fails * For instance, when requested buffer size is larger than totalram_pages(). * Relevant for buffers that use non-coherent memory. * * - Queue DMA attrs have DMA_ATTR_NO_KERNEL_MAPPING set * Relevant for buffers that use coherent memory. */ static void *vb2_dc_vaddr(struct vb2_buffer *vb, void *buf_priv) { … } static unsigned int vb2_dc_num_users(void *buf_priv) { … } static void vb2_dc_prepare(void *buf_priv) { … } static void vb2_dc_finish(void *buf_priv) { … } /*********************************************/ /* callbacks for MMAP buffers */ /*********************************************/ static void vb2_dc_put(void *buf_priv) { … } static int vb2_dc_alloc_coherent(struct vb2_dc_buf *buf) { … } static int vb2_dc_alloc_non_coherent(struct vb2_dc_buf *buf) { … } static void *vb2_dc_alloc(struct vb2_buffer *vb, struct device *dev, unsigned long size) { … } static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma) { … } /*********************************************/ /* DMABUF ops for exporters */ /*********************************************/ struct vb2_dc_attachment { … }; static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf, struct dma_buf_attachment *dbuf_attach) { … } static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf, struct dma_buf_attachment *db_attach) { … } static struct sg_table *vb2_dc_dmabuf_ops_map( struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir) { … } static void vb2_dc_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach, struct sg_table *sgt, enum dma_data_direction dma_dir) { … } static void vb2_dc_dmabuf_ops_release(struct dma_buf *dbuf) { … } static int vb2_dc_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf, enum dma_data_direction direction) { … } static int vb2_dc_dmabuf_ops_end_cpu_access(struct dma_buf *dbuf, enum dma_data_direction direction) { … } static int vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf, struct iosys_map *map) { … } static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf, struct vm_area_struct *vma) { … } static const struct dma_buf_ops vb2_dc_dmabuf_ops = …; static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf) { … } static struct dma_buf *vb2_dc_get_dmabuf(struct vb2_buffer *vb, void *buf_priv, unsigned long flags) { … } /*********************************************/ /* callbacks for USERPTR buffers */ /*********************************************/ static void vb2_dc_put_userptr(void *buf_priv) { … } static void *vb2_dc_get_userptr(struct vb2_buffer *vb, struct device *dev, unsigned long vaddr, unsigned long size) { … } /*********************************************/ /* callbacks for DMABUF buffers */ /*********************************************/ static int vb2_dc_map_dmabuf(void *mem_priv) { … } static void vb2_dc_unmap_dmabuf(void *mem_priv) { … } static void vb2_dc_detach_dmabuf(void *mem_priv) { … } static void *vb2_dc_attach_dmabuf(struct vb2_buffer *vb, struct device *dev, struct dma_buf *dbuf, unsigned long size) { … } /*********************************************/ /* DMA CONTIG exported functions */ /*********************************************/ const struct vb2_mem_ops vb2_dma_contig_memops = …; EXPORT_SYMBOL_GPL(…); /** * vb2_dma_contig_set_max_seg_size() - configure DMA max segment size * @dev: device for configuring DMA parameters * @size: size of DMA max segment size to set * * To allow mapping the scatter-list into a single chunk in the DMA * address space, the device is required to have the DMA max segment * size parameter set to a value larger than the buffer size. Otherwise, * the DMA-mapping subsystem will split the mapping into max segment * size chunks. This function sets the DMA max segment size * parameter to let DMA-mapping map a buffer as a single chunk in DMA * address space. * This code assumes that the DMA-mapping subsystem will merge all * scatterlist segments if this is really possible (for example when * an IOMMU is available and enabled). * Ideally, this parameter should be set by the generic bus code, but it * is left with the default 64KiB value due to historical litmiations in * other subsystems (like limited USB host drivers) and there no good * place to set it to the proper value. * This function should be called from the drivers, which are known to * operate on platforms with IOMMU and provide access to shared buffers * (either USERPTR or DMABUF). This should be done before initializing * videobuf2 queue. */ int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size) { … } EXPORT_SYMBOL_GPL(…); MODULE_DESCRIPTION(…) …; MODULE_AUTHOR(…) …; MODULE_LICENSE(…) …; MODULE_IMPORT_NS(…);
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