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 caches. 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 * @vmap: [optional] creates a virtual mapping for the buffer into kernel 69 * address space. Same restrictions as for vmap and friends apply. 70 * @vunmap: [optional] unmaps a vmap from the buffer 71 */ 72struct dma_buf_ops { 73 int (*attach)(struct dma_buf *, struct device *, 74 struct dma_buf_attachment *); 75 76 void (*detach)(struct dma_buf *, struct dma_buf_attachment *); 77 78 /* For {map,unmap}_dma_buf below, any specific buffer attributes 79 * required should get added to device_dma_parameters accessible 80 * via dev->dma_params. 81 */ 82 struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *, 83 enum dma_data_direction); 84 void (*unmap_dma_buf)(struct dma_buf_attachment *, 85 struct sg_table *, 86 enum dma_data_direction); 87 /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY 88 * if the call would block. 89 */ 90 91 /* after final dma_buf_put() */ 92 void (*release)(struct dma_buf *); 93 94 int (*begin_cpu_access)(struct dma_buf *, size_t, size_t, 95 enum dma_data_direction); 96 void (*end_cpu_access)(struct dma_buf *, size_t, size_t, 97 enum dma_data_direction); 98 void *(*kmap_atomic)(struct dma_buf *, unsigned long); 99 void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *); 100 void *(*kmap)(struct dma_buf *, unsigned long); 101 void (*kunmap)(struct dma_buf *, unsigned long, void *); 102 103 int (*mmap)(struct dma_buf *, struct vm_area_struct *vma); 104 105 void *(*vmap)(struct dma_buf *); 106 void (*vunmap)(struct dma_buf *, void *vaddr); 107}; 108 109/** 110 * struct dma_buf - shared buffer object 111 * @size: size of the buffer 112 * @file: file pointer used for sharing buffers across, and for refcounting. 113 * @attachments: list of dma_buf_attachment that denotes all devices attached. 114 * @ops: dma_buf_ops associated with this buffer object. 115 * @exp_name: name of the exporter; useful for debugging. 116 * @list_node: node for dma_buf accounting and debugging. 117 * @priv: exporter specific private data for this buffer object. 118 */ 119struct dma_buf { 120 size_t size; 121 struct file *file; 122 struct list_head attachments; 123 const struct dma_buf_ops *ops; 124 /* mutex to serialize list manipulation, attach/detach and vmap/unmap */ 125 struct mutex lock; 126 unsigned vmapping_counter; 127 void *vmap_ptr; 128 const char *exp_name; 129 struct list_head list_node; 130 void *priv; 131}; 132 133/** 134 * struct dma_buf_attachment - holds device-buffer attachment data 135 * @dmabuf: buffer for this attachment. 136 * @dev: device attached to the buffer. 137 * @node: list of dma_buf_attachment. 138 * @priv: exporter specific attachment data. 139 * 140 * This structure holds the attachment information between the dma_buf buffer 141 * and its user device(s). The list contains one attachment struct per device 142 * attached to the buffer. 143 */ 144struct dma_buf_attachment { 145 struct dma_buf *dmabuf; 146 struct device *dev; 147 struct list_head node; 148 void *priv; 149}; 150 151/** 152 * get_dma_buf - convenience wrapper for get_file. 153 * @dmabuf: [in] pointer to dma_buf 154 * 155 * Increments the reference count on the dma-buf, needed in case of drivers 156 * that either need to create additional references to the dmabuf on the 157 * kernel side. For example, an exporter that needs to keep a dmabuf ptr 158 * so that subsequent exports don't create a new dmabuf. 159 */ 160static inline void get_dma_buf(struct dma_buf *dmabuf) 161{ 162 get_file(dmabuf->file); 163} 164 165struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, 166 struct device *dev); 167void dma_buf_detach(struct dma_buf *dmabuf, 168 struct dma_buf_attachment *dmabuf_attach); 169 170struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops, 171 size_t size, int flags, const char *); 172 173#define dma_buf_export(priv, ops, size, flags) \ 174 dma_buf_export_named(priv, ops, size, flags, __FILE__) 175 176int dma_buf_fd(struct dma_buf *dmabuf, int flags); 177struct dma_buf *dma_buf_get(int fd); 178void dma_buf_put(struct dma_buf *dmabuf); 179 180struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *, 181 enum dma_data_direction); 182void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *, 183 enum dma_data_direction); 184int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len, 185 enum dma_data_direction dir); 186void dma_buf_end_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len, 187 enum dma_data_direction dir); 188void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long); 189void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *); 190void *dma_buf_kmap(struct dma_buf *, unsigned long); 191void dma_buf_kunmap(struct dma_buf *, unsigned long, void *); 192 193int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, 194 unsigned long); 195void *dma_buf_vmap(struct dma_buf *); 196void dma_buf_vunmap(struct dma_buf *, void *vaddr); 197int dma_buf_debugfs_create_file(const char *name, 198 int (*write)(struct seq_file *)); 199#endif /* __DMA_BUF_H__ */ 200