/*
* 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/dma-fence.h>
#include <linux/anon_inodes.h>
#include <linux/export.h>
#include <linux/debugfs.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/poll.h>
#include <linux/reservation.h>
#include <linux/mm.h>
#include <uapi/linux/dma-buf.h>
static inline int is_dma_buf_file(struct file *);
struct dma_buf_list {
struct list_head head;
struct mutex lock;
};
static struct dma_buf_list db_list;
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;
BUG_ON(dmabuf->vmapping_counter);
/*
* Any fences that a dma-buf poll can wait on should be signaled
* before releasing dma-buf. This is the responsibility of each
* driver that uses the reservation objects.
*
* If you hit this BUG() it means someone dropped their ref to the
* dma-buf while still having pending operation to the buffer.
*/
BUG_ON(dmabuf->cb_shared.active || dmabuf->cb_excl.active);
dmabuf->ops->release(dmabuf);
mutex_lock(&db_list.lock);
list_del(&dmabuf->list_node);
mutex_unlock(&db_list.lock);
if (dmabuf->resv == (struct reservation_object *)&dmabuf[1])
reservation_object_fini(dmabuf->resv);
module_put(dmabuf->owner);
kfree(dmabuf);
return 0;
}
static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
{
struct dma_buf *dmabuf;
if (!is_dma_buf_file(file))
return -EINVAL;
dmabuf = file->private_data;
/* check for overflowing the buffer's size */
if (vma->vm_pgoff + vma_pages(vma) >
dmabuf->size >> PAGE_SHIFT)
return -EINVAL;
return dmabuf->ops->mmap(dmabuf, vma);
}
static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
{
struct dma_buf *dmabuf;
loff_t base;
if (!is_dma_buf_file(file))
return -EBADF;
dmabuf = file->private_data;
/* only support discovering the end of the buffer,
but also allow SEEK_SET to maintain the idiomatic
SEEK_END(0), SEEK_CUR(0) pattern */
if (whence == SEEK_END)
base = dmabuf->size;
else if (whence == SEEK_SET)
base = 0;
else
return -EINVAL;
if (offset != 0)
return -EINVAL;
return base + offset;
}
static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
{
struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb;
unsigned long flags;
spin_lock_irqsave(&dcb->poll->lock, flags);
wake_up_locked_poll(dcb->poll, dcb->active);
dcb->active = 0;
spin_unlock_irqrestore(&dcb->poll->lock, flags);
}
static unsigned int dma_buf_poll(struct file *file, poll_table *poll)
{
struct dma_buf *dmabuf;
struct reservation_object *resv;
struct reservation_object_list *fobj;
struct dma_fence *fence_excl;
unsigned long events;
unsigned shared_count, seq;
dmabuf = file->private_data;
if (!dmabuf || !dmabuf->resv)
return POLLERR;
resv = dmabuf->resv;
poll_wait(file, &dmabuf->poll, poll);
events = poll_requested_events(poll) & (POLLIN | POLLOUT);
if (!events)
return 0;
retry:
seq = read_seqcount_begin(&resv->seq);
rcu_read_lock();
fobj = rcu_dereference(resv->fence);
if (fobj)
shared_count = fobj->shared_count;
else
shared_count = 0;
fence_excl = rcu_dereference(resv->fence_excl);
if (read_seqcount_retry(&resv->seq,