#ifndef _LINUX_VIRTIO_RING_H
#define _LINUX_VIRTIO_RING_H

#include <asm/barrier.h>
#include <linux/irqreturn.h>
#include <uapi/linux/virtio_ring.h>

/*
* Barriers in virtio are tricky. Non-SMP virtio guests can't assume
* they're not on an SMP host system, so they need to assume real
* barriers. Non-SMP virtio hosts could skip the barriers, but does
* anyone care?
*
* For virtio_pci on SMP, we don't need to order with respect to MMIO
* accesses through relaxed memory I/O windows, so smp_mb() et al are
* sufficient.
*
* For using virtio to talk to real devices (eg. other heterogeneous
* CPUs) we do need real barriers. In theory, we could be using both
* kinds of virtio, so it's a runtime decision, and the branch is
* actually quite cheap.
*/

#ifdef CONFIG_SMP
static inline void virtio_mb(bool weak_barriers)
{
if (weak_barriers)
smp_mb();
else
mb();
}

static inline void virtio_rmb(bool weak_barriers)
{
if (weak_barriers)
smp_rmb();
else
rmb();
}

static inline void virtio_wmb(bool weak_barriers)
{
if (weak_barriers)
smp_wmb();
else
wmb();
}
#else
static inline void virtio_mb(bool weak_barriers)
{
mb();
}

static inline void virtio_rmb(bool weak_barriers)
{
rmb();
}

static inline void virtio_wmb(bool weak_barriers)
{
wmb();
}
#endif

struct virtio_device;
struct virtqueue;

struct virtqueue *vring_new_virtqueue(unsigned int index,
unsigned int num,
unsigned int vring_align,
struct virtio_device *vdev,
bool weak_barriers,
void *pages,
bool (*notify)(struct virtqueue *vq),
void (*callback)(struct virtqueue *vq),
const char *name);
void vring_del_virtqueue(struct virtqueue *vq);
/* Filter out transport-specific feature bits. */
void vring_transport_features(struct virtio_device *vdev);

irqreturn_t vring_interrupt(int irq, void *_vq);
#endif /* _LINUX_VIRTIO_RING_H */