/* * Header file for dma buffer sharing framework. * * Copyright(C) 2011 Linaro Limited. All rights reserved. * Author: Sumit Semwal * * Many thanks to linaro-mm-sig list, and specially * Arnd Bergmann , Rob Clark and * Daniel Vetter 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 . */ #ifndef __DMA_BUF_H__ #define __DMA_BUF_H__ #include #include #include #include #include #include #include #include struct device; 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. * @begin_cpu_access: [optional] called before cpu access to invalidate cpu * caches and allocate backing storage (if not yet done) * respectively pin the object into memory. * @end_cpu_access: [optional] called after cpu access to flush caches. * @kmap_atomic: maps a page from the buffer into kernel address * space, users may not block until the subsequent unmap call. * This callback must not sleep. * @kunmap_atomic: [optional] unmaps a atomically mapped page from the buffer. * This Callback must not sleep. * @kmap: maps a page from the buffer into kernel address space. * @kunmap: [optional] unmaps a page from the buffer. * @mmap: used to expose the backing storage to userspace. Note that the * mapping needs to be coherent - if the exporter doesn't directly * support this, it needs to fake coherency by shooting down any ptes * when transitioning away from the cpu domain. * @vmap: [optional] creates a virtual mapping for the buffer into kernel * address space. Same restrictions as for vmap and friends apply. * @vunmap: [optional] unmaps a vmap from the buffer */ 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 *, enum dma_data_direction); /* 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 *); int (*begin_cpu_access)(struct dma_buf *, enum dma_data_direction); int (*end_cpu_access)(struct dma_buf *, enum dma_data_direction); void *(*kmap_atomic)(struct dma_buf *, unsigned long); void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *); void *(*kmap)(struct dma_buf *, unsigned long); void (*kunmap)(struct dma_buf *, unsigned long, void *); int (*mmap)(struct dma_buf *, struct vm_area_struct *vma); void *(*vmap)(struct dma_buf *); void (*vunmap)(struct dma_buf *, void *vaddr); }; /** * 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. * @exp_name: name of the exporter; useful for debugging. * @owner: pointer to exporter module; used for refcounting when exporter is a * kernel module. * @list_node: node for dma_buf accounting and debugging. * @priv: exporter specific private data for this buffer object. * @resv: reservation object linked to this dma-buf */ struct dma_buf { size_t size; struct file *file; struct list_head attachments; const struct dma_buf_ops *ops; /* mutex to serialize list manipulation, attach/detach and vmap/unmap */ struct mutex lock; unsigned vmapping_counter; void *vmap_ptr; const char *exp_name; struct list_head list_node; 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; }; /** * struct dma_buf_export_info - holds information needed to export a dma_buf * @exp_name: name of the exporter - useful for debugging. * @owner: pointer to exporter module - used for refcounting kernel module * @ops: Attach allocator-defined dma buf ops to the new buffer * @size: Size of the buffer * @flags: mode flags for the file * @resv: reservation-object, NULL to allocate default one * @priv: Attach private data of allocator to this buffer * * This structure holds the information required to export the buffer. Used * with dma_buf_export() only. */ struct dma_buf_export_info { const char *exp_name; struct module *owner; const struct dma_buf_ops *ops; size_t size; int flags; struct reservation_object *resv; void *priv; }; /** * helper macro for exporters; zeros and fills in most common values */ #define DEFINE_DMA_BUF_EXPORT_INFO(a) \ struct dma_buf_export_info a = { .exp_name = KBUILD_MODNAME, \ .owner = THIS_MODULE } /** * get_dma_buf - convenience wrapper for get_file. * @dmabuf: [in] pointer to dma_buf * * Increments the reference count on the dma-buf, needed in case of drivers * that either need to create additional references to the dmabuf on the * kernel side. For example, an exporter that needs to keep a dmabuf ptr * so that subsequent exports don't create a new dmabuf. */ 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(const struct dma_buf_export_info *exp_info); int dma_buf_fd(struct dma_buf *dmabuf, int flags); 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 *, enum dma_data_direction); int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction dir); int dma_buf_end_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction dir); void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long); void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *); void *dma_buf_kmap(struct dma_buf *, unsigned long); void dma_buf_kunmap(struct dma_buf *, unsigned long, void *); int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, unsigned long); void *dma_buf_vmap(struct dma_buf *); void dma_buf_vunmap(struct dma_buf *, void *vaddr); int dma_buf_debugfs_create_file(const char *name, int (*write)(struct seq_file *)); #endif /* __DMA_BUF_H__ */