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Diffstat (limited to 'include/linux/dma-buf.h')
| -rw-r--r-- | include/linux/dma-buf.h | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h new file mode 100644 index 00000000000..f8ac076afa5 --- /dev/null +++ b/include/linux/dma-buf.h @@ -0,0 +1,176 @@ +/* + * Header file for dma buffer sharing framework. + * + * Copyright(C) 2011 Linaro Limited. All rights reserved. + * Author: Sumit Semwal <sumit.semwal@ti.com> + * + * Many thanks to linaro-mm-sig list, and specially + * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and + * Daniel Vetter <daniel@ffwll.ch> for their support in creation and + * refining of this idea. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program. If not, see <http://www.gnu.org/licenses/>. + */ +#ifndef __DMA_BUF_H__ +#define __DMA_BUF_H__ + +#include <linux/file.h> +#include <linux/err.h> +#include <linux/device.h> +#include <linux/scatterlist.h> +#include <linux/list.h> +#include <linux/dma-mapping.h> + +struct dma_buf; +struct dma_buf_attachment; + +/** + * struct dma_buf_ops - operations possible on struct dma_buf + * @attach: [optional] allows different devices to 'attach' themselves to the + * given buffer. It might return -EBUSY to signal that backing storage + * is already allocated and incompatible with the requirements + * of requesting device. + * @detach: [optional] detach a given device from this buffer. + * @map_dma_buf: returns list of scatter pages allocated, increases usecount + * of the buffer. Requires atleast one attach to be called + * before. Returned sg list should already be mapped into + * _device_ address space. This call may sleep. May also return + * -EINTR. Should return -EINVAL if attach hasn't been called yet. + * @unmap_dma_buf: decreases usecount of buffer, might deallocate scatter + * pages. + * @release: release this buffer; to be called after the last dma_buf_put. + */ +struct dma_buf_ops { + int (*attach)(struct dma_buf *, struct device *, + struct dma_buf_attachment *); + + void (*detach)(struct dma_buf *, struct dma_buf_attachment *); + + /* For {map,unmap}_dma_buf below, any specific buffer attributes + * required should get added to device_dma_parameters accessible + * via dev->dma_params. + */ + struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *, + enum dma_data_direction); + void (*unmap_dma_buf)(struct dma_buf_attachment *, + struct sg_table *); + /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY + * if the call would block. + */ + + /* after final dma_buf_put() */ + void (*release)(struct dma_buf *); + +}; + +/** + * struct dma_buf - shared buffer object + * @size: size of the buffer + * @file: file pointer used for sharing buffers across, and for refcounting. + * @attachments: list of dma_buf_attachment that denotes all devices attached. + * @ops: dma_buf_ops associated with this buffer object. + * @priv: exporter specific private data for this buffer object. + */ +struct dma_buf { + size_t size; + struct file *file; + struct list_head attachments; + const struct dma_buf_ops *ops; + /* mutex to serialize list manipulation and other ops */ + struct mutex lock; + void *priv; +}; + +/** + * struct dma_buf_attachment - holds device-buffer attachment data + * @dmabuf: buffer for this attachment. + * @dev: device attached to the buffer. + * @node: list of dma_buf_attachment. + * @priv: exporter specific attachment data. + * + * This structure holds the attachment information between the dma_buf buffer + * and its user device(s). The list contains one attachment struct per device + * attached to the buffer. + */ +struct dma_buf_attachment { + struct dma_buf *dmabuf; + struct device *dev; + struct list_head node; + void *priv; +}; + +#ifdef CONFIG_DMA_SHARED_BUFFER +struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, + struct device *dev); +void dma_buf_detach(struct dma_buf *dmabuf, + struct dma_buf_attachment *dmabuf_attach); +struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops, + size_t size, int flags); +int dma_buf_fd(struct dma_buf *dmabuf); +struct dma_buf *dma_buf_get(int fd); +void dma_buf_put(struct dma_buf *dmabuf); + +struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *, + enum dma_data_direction); +void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *); +#else + +static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, + struct device *dev) +{ + return ERR_PTR(-ENODEV); +} + +static inline void dma_buf_detach(struct dma_buf *dmabuf, + struct dma_buf_attachment *dmabuf_attach) +{ + return; +} + +static inline struct dma_buf *dma_buf_export(void *priv, + struct dma_buf_ops *ops, + size_t size, int flags) +{ + return ERR_PTR(-ENODEV); +} + +static inline int dma_buf_fd(struct dma_buf *dmabuf) +{ + return -ENODEV; +} + +static inline struct dma_buf *dma_buf_get(int fd) +{ + return ERR_PTR(-ENODEV); +} + +static inline void dma_buf_put(struct dma_buf *dmabuf) +{ + return; +} + +static inline struct sg_table *dma_buf_map_attachment( + struct dma_buf_attachment *attach, enum dma_data_direction write) +{ + return ERR_PTR(-ENODEV); +} + +static inline void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, + struct sg_table *sg) +{ + return; +} + +#endif /* CONFIG_DMA_SHARED_BUFFER */ + +#endif /* __DMA_BUF_H__ */ |