/*
* Framework for buffer objects that can be shared across devices/subsystems.
*
* 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/>.
*/
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/dma-buf.h>
#include <linux/anon_inodes.h>
#include <linux/export.h>
static inline int is_dma_buf_file(struct file *);
static int dma_buf_release(struct inode *inode, struct file *file)
{
struct dma_buf *dmabuf;
if (!is_dma_buf_file(file))
return -EINVAL;
dmabuf = file->private_data;
dmabuf->ops->release(dmabuf);
kfree(dmabuf);
return 0;
}
static const struct file_operations dma_buf_fops = {
.release = dma_buf_release,
};
/*
* is_dma_buf_file - Check if struct file* is associated with dma_buf
*/
static inline int is_dma_buf_file(struct file *file)
{
return file->f_op == &dma_buf_fops;
}
/**
* dma_buf_export - Creates a new dma_buf, and associates an anon file
* with this buffer, so it can be exported.
* Also connect the allocator specific data and ops to the buffer.
*
* @priv: [in] Attach private data of allocator to this buffer
* @ops: [in] Attach allocator-defined dma buf ops to the new buffer.
* @size: [in] Size of the buffer
* @flags: [in] mode flags for the file.
*
* Returns, on success, a newly created dma_buf object, which wraps the
* supplied private data and operations for dma_buf_ops. On either missing
* ops, or error in allocating struct dma_buf, will return negative error.
*
*/
struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
size_t size, int flags)
{
struct dma_buf *dmabuf;
struct file *file;
if (WARN_ON(!priv || !ops
|| !ops->map_dma_buf
|| !ops->unmap_dma_buf
|| !ops->release)) {
return ERR_PTR(-EINVAL);
}
dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
if (dmabuf == NULL)
return ERR_PTR(-ENOMEM);
dmabuf->priv = priv;
dmabuf->ops = ops;
dmabuf->size = size;
file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
dmabuf->file = file;
mutex_init(&dmabuf->lock);
INIT_LIST_HEAD(&dmabuf->attachments);
return dmabuf;
}
EXPORT_SYMBOL_GPL(dma_buf_export);
/**
* dma_buf_fd - returns a file descriptor for the given dma_buf
* @dmabuf: [in] pointer to dma_buf for which fd is required.
*
* On success, returns an associated 'fd'. Else, returns error.
*/
int dma_buf_fd(struct dma_buf *dmabuf)
{
int error, fd;
if (!dmabuf || !dmabuf->file)
return -EINVAL;
error = get_unused_fd();
if (error < 0)
return error;
fd = error;
fd_install(fd, dmabuf->file);
return fd;
}
EXPORT_SYMBOL_GPL(dma_buf_fd);
/**
* dma_buf_get - returns the dma_buf structure related to an fd
* @fd: [in] fd associated with the dma_buf to be returned
*
* On success, returns the dma_buf structure associated with an fd; uses
* file's refcounting done by fget to increase refcount. returns ERR_PTR
* otherwise.
*/
struct dma_buf *dma_buf_get(int fd)
{
struct file *file;
file = fget(fd);
if (!file)
return ERR_PTR(-EBADF);
if (!is_dma_buf_file(file)) {
fput(file);
return ERR_PTR(-EINVAL);
}
return file->private_data;
}
EXPORT_SYMBOL_GPL(dma_buf_get);
/**
* dma_buf_put - decreases refcount of the buffer
* @dmabuf: [in] buffer to reduce refcount of
*
* Uses file's refcounting done implicitly by fput()
*/
void dma_buf_put(struct dma_buf *dmabuf)
{
if (WARN_ON(!dmabuf || !dmabuf->file))
return;
fput(dmabuf->file);
}
EXPORT_SYMBOL_GPL(dma_buf_put);
/**
* dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
* calls attach() of dma_buf_ops to allow device-specific attach functionality
* @dmabuf: [in] buffer to attach device to.
* @dev: [in] device to be attached.
*
* Returns struct dma_buf_attachment * for this attachment; may return negative
* error codes.
*
*/
struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
struct device *dev)
{
struct dma_buf_attachment *attach;
int ret;
if (WARN_ON(!dmabuf || !dev || !dmabuf->ops))
return ERR_PTR(-EINVAL);
attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
if (attach == NULL)
goto err_alloc;
mutex_lock(&dmabuf->lock);
attach->dev = dev;
attach->dmabuf = dmabuf;
if (dmabuf->ops->attach) {
ret = dmabuf->ops->attach(dmabuf, dev, attach);
if (ret)
goto err_attach;
}
list_add(&attach->node, &dmabuf->attachments);
mutex_unlock(&dmabuf->lock);
return attach;
err_alloc:
return ERR_PTR(-ENOMEM);
err_attach:
kfree(attach);
mutex_unlock(&dmabuf->lock);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(dma_buf_attach);
/**
* dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
* optionally calls detach() of dma_buf_ops for device-specific detach
* @dmabuf: [in] buffer to detach from.
* @attach: [in] attachment to be detached; is free'd after this call.
*
*/
void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
{
if (WARN_ON(!dmabuf || !attach || !dmabuf->ops))
return;
mutex_lock(&dmabuf->lock);
list_del(&attach->node);
if (dmabuf->ops->detach)
dmabuf->ops->detach(dmabuf, attach);
mutex_unlock(&dmabuf->lock);
kfree(attach);
}
EXPORT_SYMBOL_GPL(dma_buf_detach);
/**
* dma_buf_map_attachment - Returns the scatterlist table of the attachment;
* mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
* dma_buf_ops.
* @attach: [in] attachment whose scatterlist is to be returned
* @direction: [in] direction of DMA transfer
*
* Returns sg_table containing the scatterlist to be returned; may return NULL
* or ERR_PTR.
*
*/
struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
enum dma_data_direction direction)
{
struct sg_table *sg_table = ERR_PTR(-EINVAL);
might_sleep();
if (WARN_ON(!attach || !attach->dmabuf || !attach->dmabuf->ops))
return ERR_PTR(-EINVAL);
mutex_lock(&attach->dmabuf->lock);
if (attach->dmabuf->ops->map_dma_buf)
sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
mutex_unlock(&attach->dmabuf->lock);
return sg_table;
}
EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
/**
* dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
* deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
* dma_buf_ops.
* @attach: [in] attachment to unmap buffer from
* @sg_table: [in] scatterlist info of the buffer to unmap
*
*/
void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
struct sg_table *sg_table)
{
if (WARN_ON(!attach || !attach->dmabuf || !sg_table
|| !attach->dmabuf->ops))
return;
mutex_lock(&attach->dmabuf->lock);
if (attach->dmabuf->ops->unmap_dma_buf)
attach->dmabuf->ops->unmap_dma_buf(attach, sg_table);
mutex_unlock(&attach->dmabuf->lock);
}
EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
