1/* 2 * Header file for dma buffer sharing framework. 3 * 4 * Copyright(C) 2011 Linaro Limited. All rights reserved. 5 * Author: Sumit Semwal <sumit.semwal@ti.com> 6 * 7 * Many thanks to linaro-mm-sig list, and specially 8 * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and 9 * Daniel Vetter <daniel@ffwll.ch> for their support in creation and 10 * refining of this idea. 11 * 12 * This program is free software; you can redistribute it and/or modify it 13 * under the terms of the GNU General Public License version 2 as published by 14 * the Free Software Foundation. 15 * 16 * This program is distributed in the hope that it will be useful, but WITHOUT 17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 18 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 19 * more details. 20 * 21 * You should have received a copy of the GNU General Public License along with 22 * this program. If not, see <http://www.gnu.org/licenses/>. 23 */ 24#ifndef __DMA_BUF_H__ 25#define __DMA_BUF_H__ 26 27#include <linux/file.h> 28#include <linux/err.h> 29#include <linux/scatterlist.h> 30#include <linux/list.h> 31#include <linux/dma-mapping.h> 32#include <linux/fs.h> 33 34struct device; 35struct dma_buf; 36struct dma_buf_attachment; 37 38/** 39 * struct dma_buf_ops - operations possible on struct dma_buf 40 * @attach: [optional] allows different devices to 'attach' themselves to the 41 * given buffer. It might return -EBUSY to signal that backing storage 42 * is already allocated and incompatible with the requirements 43 * of requesting device. 44 * @detach: [optional] detach a given device from this buffer. 45 * @map_dma_buf: returns list of scatter pages allocated, increases usecount 46 * of the buffer. Requires atleast one attach to be called 47 * before. Returned sg list should already be mapped into 48 * _device_ address space. This call may sleep. May also return 49 * -EINTR. Should return -EINVAL if attach hasn't been called yet. 50 * @unmap_dma_buf: decreases usecount of buffer, might deallocate scatter 51 * pages. 52 * @release: release this buffer; to be called after the last dma_buf_put. 53 * @begin_cpu_access: [optional] called before cpu access to invalidate cpu 54 * caches and allocate backing storage (if not yet done) 55 * respectively pin the objet into memory. 56 * @end_cpu_access: [optional] called after cpu access to flush cashes. 57 * @kmap_atomic: maps a page from the buffer into kernel address 58 * space, users may not block until the subsequent unmap call. 59 * This callback must not sleep. 60 * @kunmap_atomic: [optional] unmaps a atomically mapped page from the buffer. 61 * This Callback must not sleep. 62 * @kmap: maps a page from the buffer into kernel address space. 63 * @kunmap: [optional] unmaps a page from the buffer. 64 * @mmap: used to expose the backing storage to userspace. Note that the 65 * mapping needs to be coherent - if the exporter doesn't directly 66 * support this, it needs to fake coherency by shooting down any ptes 67 * when transitioning away from the cpu domain. 68 */ 69struct dma_buf_ops { 70 int (*attach)(struct dma_buf *, struct device *, 71 struct dma_buf_attachment *); 72 73 void (*detach)(struct dma_buf *, struct dma_buf_attachment *); 74 75 /* For {map,unmap}_dma_buf below, any specific buffer attributes 76 * required should get added to device_dma_parameters accessible 77 * via dev->dma_params. 78 */ 79 struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *, 80 enum dma_data_direction); 81 void (*unmap_dma_buf)(struct dma_buf_attachment *, 82 struct sg_table *, 83 enum dma_data_direction); 84 /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY 85 * if the call would block. 86 */ 87 88 /* after final dma_buf_put() */ 89 void (*release)(struct dma_buf *); 90 91 int (*begin_cpu_access)(struct dma_buf *, size_t, size_t, 92 enum dma_data_direction); 93 void (*end_cpu_access)(struct dma_buf *, size_t, size_t, 94 enum dma_data_direction); 95 void *(*kmap_atomic)(struct dma_buf *, unsigned long); 96 void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *); 97 void *(*kmap)(struct dma_buf *, unsigned long); 98 void (*kunmap)(struct dma_buf *, unsigned long, void *); 99 100 int (*mmap)(struct dma_buf *, struct vm_area_struct *vma); 101}; 102 103/** 104 * struct dma_buf - shared buffer object 105 * @size: size of the buffer 106 * @file: file pointer used for sharing buffers across, and for refcounting. 107 * @attachments: list of dma_buf_attachment that denotes all devices attached. 108 * @ops: dma_buf_ops associated with this buffer object. 109 * @priv: exporter specific private data for this buffer object. 110 */ 111struct dma_buf { 112 size_t size; 113 struct file *file; 114 struct list_head attachments; 115 const struct dma_buf_ops *ops; 116 /* mutex to serialize list manipulation and attach/detach */ 117 struct mutex lock; 118 void *priv; 119}; 120 121/** 122 * struct dma_buf_attachment - holds device-buffer attachment data 123 * @dmabuf: buffer for this attachment. 124 * @dev: device attached to the buffer. 125 * @node: list of dma_buf_attachment. 126 * @priv: exporter specific attachment data. 127 * 128 * This structure holds the attachment information between the dma_buf buffer 129 * and its user device(s). The list contains one attachment struct per device 130 * attached to the buffer. 131 */ 132struct dma_buf_attachment { 133 struct dma_buf *dmabuf; 134 struct device *dev; 135 struct list_head node; 136 void *priv; 137}; 138 139/** 140 * get_dma_buf - convenience wrapper for get_file. 141 * @dmabuf: [in] pointer to dma_buf 142 * 143 * Increments the reference count on the dma-buf, needed in case of drivers 144 * that either need to create additional references to the dmabuf on the 145 * kernel side. For example, an exporter that needs to keep a dmabuf ptr 146 * so that subsequent exports don't create a new dmabuf. 147 */ 148static inline void get_dma_buf(struct dma_buf *dmabuf) 149{ 150 get_file(dmabuf->file); 151} 152 153#ifdef CONFIG_DMA_SHARED_BUFFER 154struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, 155 struct device *dev); 156void dma_buf_detach(struct dma_buf *dmabuf, 157 struct dma_buf_attachment *dmabuf_attach); 158struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops, 159 size_t size, int flags); 160int dma_buf_fd(struct dma_buf *dmabuf, int flags); 161struct dma_buf *dma_buf_get(int fd); 162void dma_buf_put(struct dma_buf *dmabuf); 163 164struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *, 165 enum dma_data_direction); 166void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *, 167 enum dma_data_direction); 168int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len, 169 enum dma_data_direction dir); 170void dma_buf_end_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len, 171 enum dma_data_direction dir); 172void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long); 173void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *); 174void *dma_buf_kmap(struct dma_buf *, unsigned long); 175void dma_buf_kunmap(struct dma_buf *, unsigned long, void *); 176 177int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, 178 unsigned long); 179#else 180 181static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, 182 struct device *dev) 183{ 184 return ERR_PTR(-ENODEV); 185} 186 187static inline void dma_buf_detach(struct dma_buf *dmabuf, 188 struct dma_buf_attachment *dmabuf_attach) 189{ 190 return; 191} 192 193static inline struct dma_buf *dma_buf_export(void *priv, 194 const struct dma_buf_ops *ops, 195 size_t size, int flags) 196{ 197 return ERR_PTR(-ENODEV); 198} 199 200static inline int dma_buf_fd(struct dma_buf *dmabuf, int flags) 201{ 202 return -ENODEV; 203} 204 205static inline struct dma_buf *dma_buf_get(int fd) 206{ 207 return ERR_PTR(-ENODEV); 208} 209 210static inline void dma_buf_put(struct dma_buf *dmabuf) 211{ 212 return; 213} 214 215static inline struct sg_table *dma_buf_map_attachment( 216 struct dma_buf_attachment *attach, enum dma_data_direction write) 217{ 218 return ERR_PTR(-ENODEV); 219} 220 221static inline void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, 222 struct sg_table *sg, enum dma_data_direction dir) 223{ 224 return; 225} 226 227static inline int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, 228 size_t start, size_t len, 229 enum dma_data_direction dir) 230{ 231 return -ENODEV; 232} 233 234static inline void dma_buf_end_cpu_access(struct dma_buf *dmabuf, 235 size_t start, size_t len, 236 enum dma_data_direction dir) 237{ 238} 239 240static inline void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, 241 unsigned long pnum) 242{ 243 return NULL; 244} 245 246static inline void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, 247 unsigned long pnum, void *vaddr) 248{ 249} 250 251static inline void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long pnum) 252{ 253 return NULL; 254} 255 256static inline void dma_buf_kunmap(struct dma_buf *dmabuf, 257 unsigned long pnum, void *vaddr) 258{ 259} 260 261static inline int dma_buf_mmap(struct dma_buf *dmabuf, 262 struct vm_area_struct *vma, 263 unsigned long pgoff) 264{ 265 return -ENODEV; 266} 267#endif /* CONFIG_DMA_SHARED_BUFFER */ 268 269#endif /* __DMA_BUF_H__ */ 270