1#ifndef _LINUX_VIRTIO_RING_H
2#define _LINUX_VIRTIO_RING_H
3
4#include <asm/barrier.h>
5#include <linux/irqreturn.h>
6#include <uapi/linux/virtio_ring.h>
7
8/*
9 * Barriers in virtio are tricky.  Non-SMP virtio guests can't assume
10 * they're not on an SMP host system, so they need to assume real
11 * barriers.  Non-SMP virtio hosts could skip the barriers, but does
12 * anyone care?
13 *
14 * For virtio_pci on SMP, we don't need to order with respect to MMIO
15 * accesses through relaxed memory I/O windows, so smp_mb() et al are
16 * sufficient.
17 *
18 * For using virtio to talk to real devices (eg. other heterogeneous
19 * CPUs) we do need real barriers.  In theory, we could be using both
20 * kinds of virtio, so it's a runtime decision, and the branch is
21 * actually quite cheap.
22 */
23
24static inline void virtio_mb(bool weak_barriers)
25{
26#ifdef CONFIG_SMP
27	if (weak_barriers)
28		smp_mb();
29	else
30#endif
31		mb();
32}
33
34static inline void virtio_rmb(bool weak_barriers)
35{
36	if (weak_barriers)
37		dma_rmb();
38	else
39		rmb();
40}
41
42static inline void virtio_wmb(bool weak_barriers)
43{
44	if (weak_barriers)
45		dma_wmb();
46	else
47		wmb();
48}
49
50struct virtio_device;
51struct virtqueue;
52
53struct virtqueue *vring_new_virtqueue(unsigned int index,
54				      unsigned int num,
55				      unsigned int vring_align,
56				      struct virtio_device *vdev,
57				      bool weak_barriers,
58				      void *pages,
59				      bool (*notify)(struct virtqueue *vq),
60				      void (*callback)(struct virtqueue *vq),
61				      const char *name);
62void vring_del_virtqueue(struct virtqueue *vq);
63/* Filter out transport-specific feature bits. */
64void vring_transport_features(struct virtio_device *vdev);
65
66irqreturn_t vring_interrupt(int irq, void *_vq);
67#endif /* _LINUX_VIRTIO_RING_H */
68