292 lines
7.4 KiB
C
292 lines
7.4 KiB
C
![]() |
/*
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* Framework for buffer objects that can be shared across devices/subsystems.
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*
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* Copyright(C) 2011 Linaro Limited. All rights reserved.
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* Author: Sumit Semwal <sumit.semwal@ti.com>
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*
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* Many thanks to linaro-mm-sig list, and specially
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* Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
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* Daniel Vetter <daniel@ffwll.ch> for their support in creation and
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* refining of this idea.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/fs.h>
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#include <linux/slab.h>
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#include <linux/dma-buf.h>
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#include <linux/anon_inodes.h>
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#include <linux/export.h>
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static inline int is_dma_buf_file(struct file *);
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static int dma_buf_release(struct inode *inode, struct file *file)
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{
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struct dma_buf *dmabuf;
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if (!is_dma_buf_file(file))
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return -EINVAL;
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dmabuf = file->private_data;
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dmabuf->ops->release(dmabuf);
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kfree(dmabuf);
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return 0;
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}
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static const struct file_operations dma_buf_fops = {
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.release = dma_buf_release,
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};
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/*
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* is_dma_buf_file - Check if struct file* is associated with dma_buf
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*/
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static inline int is_dma_buf_file(struct file *file)
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{
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return file->f_op == &dma_buf_fops;
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}
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/**
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* dma_buf_export - Creates a new dma_buf, and associates an anon file
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* with this buffer, so it can be exported.
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* Also connect the allocator specific data and ops to the buffer.
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*
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* @priv: [in] Attach private data of allocator to this buffer
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* @ops: [in] Attach allocator-defined dma buf ops to the new buffer.
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* @size: [in] Size of the buffer
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* @flags: [in] mode flags for the file.
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*
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* Returns, on success, a newly created dma_buf object, which wraps the
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* supplied private data and operations for dma_buf_ops. On either missing
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* ops, or error in allocating struct dma_buf, will return negative error.
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*
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*/
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struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
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size_t size, int flags)
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{
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struct dma_buf *dmabuf;
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struct file *file;
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if (WARN_ON(!priv || !ops
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|| !ops->map_dma_buf
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|| !ops->unmap_dma_buf
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|| !ops->release)) {
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return ERR_PTR(-EINVAL);
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}
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dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
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if (dmabuf == NULL)
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return ERR_PTR(-ENOMEM);
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dmabuf->priv = priv;
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dmabuf->ops = ops;
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dmabuf->size = size;
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file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
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dmabuf->file = file;
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mutex_init(&dmabuf->lock);
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INIT_LIST_HEAD(&dmabuf->attachments);
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return dmabuf;
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}
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EXPORT_SYMBOL_GPL(dma_buf_export);
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/**
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* dma_buf_fd - returns a file descriptor for the given dma_buf
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* @dmabuf: [in] pointer to dma_buf for which fd is required.
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*
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* On success, returns an associated 'fd'. Else, returns error.
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*/
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int dma_buf_fd(struct dma_buf *dmabuf)
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{
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int error, fd;
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if (!dmabuf || !dmabuf->file)
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return -EINVAL;
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error = get_unused_fd();
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if (error < 0)
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return error;
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fd = error;
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fd_install(fd, dmabuf->file);
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return fd;
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}
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EXPORT_SYMBOL_GPL(dma_buf_fd);
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/**
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* dma_buf_get - returns the dma_buf structure related to an fd
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* @fd: [in] fd associated with the dma_buf to be returned
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*
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* On success, returns the dma_buf structure associated with an fd; uses
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* file's refcounting done by fget to increase refcount. returns ERR_PTR
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* otherwise.
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*/
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struct dma_buf *dma_buf_get(int fd)
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{
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struct file *file;
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file = fget(fd);
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if (!file)
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return ERR_PTR(-EBADF);
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if (!is_dma_buf_file(file)) {
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fput(file);
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return ERR_PTR(-EINVAL);
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}
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return file->private_data;
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}
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EXPORT_SYMBOL_GPL(dma_buf_get);
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/**
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* dma_buf_put - decreases refcount of the buffer
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* @dmabuf: [in] buffer to reduce refcount of
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*
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* Uses file's refcounting done implicitly by fput()
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*/
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void dma_buf_put(struct dma_buf *dmabuf)
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{
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if (WARN_ON(!dmabuf || !dmabuf->file))
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return;
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fput(dmabuf->file);
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}
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EXPORT_SYMBOL_GPL(dma_buf_put);
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/**
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* dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
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* calls attach() of dma_buf_ops to allow device-specific attach functionality
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* @dmabuf: [in] buffer to attach device to.
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* @dev: [in] device to be attached.
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*
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* Returns struct dma_buf_attachment * for this attachment; may return negative
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* error codes.
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*
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*/
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struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
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struct device *dev)
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{
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struct dma_buf_attachment *attach;
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int ret;
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if (WARN_ON(!dmabuf || !dev || !dmabuf->ops))
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return ERR_PTR(-EINVAL);
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attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
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if (attach == NULL)
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goto err_alloc;
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mutex_lock(&dmabuf->lock);
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attach->dev = dev;
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attach->dmabuf = dmabuf;
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if (dmabuf->ops->attach) {
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ret = dmabuf->ops->attach(dmabuf, dev, attach);
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if (ret)
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goto err_attach;
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}
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list_add(&attach->node, &dmabuf->attachments);
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mutex_unlock(&dmabuf->lock);
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return attach;
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err_alloc:
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return ERR_PTR(-ENOMEM);
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err_attach:
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kfree(attach);
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mutex_unlock(&dmabuf->lock);
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return ERR_PTR(ret);
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}
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EXPORT_SYMBOL_GPL(dma_buf_attach);
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/**
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* dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
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* optionally calls detach() of dma_buf_ops for device-specific detach
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* @dmabuf: [in] buffer to detach from.
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* @attach: [in] attachment to be detached; is free'd after this call.
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*
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*/
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void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
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{
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if (WARN_ON(!dmabuf || !attach || !dmabuf->ops))
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return;
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mutex_lock(&dmabuf->lock);
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list_del(&attach->node);
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if (dmabuf->ops->detach)
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dmabuf->ops->detach(dmabuf, attach);
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mutex_unlock(&dmabuf->lock);
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kfree(attach);
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}
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EXPORT_SYMBOL_GPL(dma_buf_detach);
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/**
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* dma_buf_map_attachment - Returns the scatterlist table of the attachment;
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* mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
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* dma_buf_ops.
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* @attach: [in] attachment whose scatterlist is to be returned
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* @direction: [in] direction of DMA transfer
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*
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* Returns sg_table containing the scatterlist to be returned; may return NULL
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* or ERR_PTR.
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*
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*/
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struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
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enum dma_data_direction direction)
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{
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struct sg_table *sg_table = ERR_PTR(-EINVAL);
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might_sleep();
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if (WARN_ON(!attach || !attach->dmabuf || !attach->dmabuf->ops))
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return ERR_PTR(-EINVAL);
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mutex_lock(&attach->dmabuf->lock);
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if (attach->dmabuf->ops->map_dma_buf)
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sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
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mutex_unlock(&attach->dmabuf->lock);
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return sg_table;
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}
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EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
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/**
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* dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
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* deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
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* dma_buf_ops.
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* @attach: [in] attachment to unmap buffer from
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* @sg_table: [in] scatterlist info of the buffer to unmap
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*
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*/
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void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
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struct sg_table *sg_table)
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{
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if (WARN_ON(!attach || !attach->dmabuf || !sg_table
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|| !attach->dmabuf->ops))
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return;
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mutex_lock(&attach->dmabuf->lock);
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if (attach->dmabuf->ops->unmap_dma_buf)
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attach->dmabuf->ops->unmap_dma_buf(attach, sg_table);
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mutex_unlock(&attach->dmabuf->lock);
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}
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EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
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