[UNIKRAFT PATCH RFCv3 01/32] plat/virtio: Introduce several helpers for virtio ring

[Jia He <justin.he@xxxxxxx>]

This patch provides several virtqueue helpers for virtio mmio
initialization.

Signed-off-by: Jia He <justin.he@xxxxxxx>
---
 plat/drivers/include/virtio/virtqueue.h | 33 +++++++++++++++++++++++++
 plat/drivers/virtio/virtio_ring.c       | 32 ++++++++++++++++++++++++
 2 files changed, 65 insertions(+)

diff --git a/plat/drivers/include/virtio/virtqueue.h 
b/plat/drivers/include/virtio/virtqueue.h
index 1479828..a717541 100644
--- a/plat/drivers/include/virtio/virtqueue.h
+++ b/plat/drivers/include/virtio/virtqueue.h
@@ -82,6 +82,39 @@ struct virtqueue {
  */
 __phys_addr virtqueue_physaddr(struct virtqueue *vq);
 
+/**
+ * Fetch the avail address of the descriptor ring.
+ * @param vq
+ *     Reference to the virtqueue.
+ *
+ * @return
+ *     Return the guest avail address of the vring.
+ */
+__phys_addr virtqueue_get_avail_addr(struct virtqueue *vq);
+
+/**
+ * Fetch the used address of the descriptor ring.
+ * @param vq
+ *     Reference to the virtqueue.
+ *
+ * @return
+ *     Return the guest used address of the vring.
+ */
+__phys_addr virtqueue_get_used_addr(struct virtqueue *vq);
+
+/**
+ * Get the number of vring for virtqueue
+ *
+ * @param vq
+ *     Reference to the virtual queue
+ *
+ * @return
+ *     the number of vring for virtqueue
+ *
+ */
+unsigned int virtqueue_vring_get_num(struct virtqueue *vq);
+
+
 /**
  * Ring interrupt handler. This function is invoked from the interrupt handler
  * in the virtio device for interrupt specific to the ring.
diff --git a/plat/drivers/virtio/virtio_ring.c 
b/plat/drivers/virtio/virtio_ring.c
index ab9287a..0f39895 100644
--- a/plat/drivers/virtio/virtio_ring.c
+++ b/plat/drivers/virtio/virtio_ring.c
@@ -262,6 +262,38 @@ __phys_addr virtqueue_physaddr(struct virtqueue *vq)
        return ukplat_virt_to_phys(vrq->vring_mem);
 }
 
+__phys_addr virtqueue_get_avail_addr(struct virtqueue *vq)
+{
+       struct virtqueue_vring *vrq = NULL;
+
+       UK_ASSERT(vq);
+
+       vrq = to_virtqueue_vring(vq);
+       return virtqueue_physaddr(vq) +
+               ((char *)vrq->vring.avail - (char *)vrq->vring.desc);
+}
+
+__phys_addr virtqueue_get_used_addr(struct virtqueue *vq)
+{
+       struct virtqueue_vring *vrq = NULL;
+
+       UK_ASSERT(vq);
+
+       vrq = to_virtqueue_vring(vq);
+       return virtqueue_physaddr(vq) +
+               ((char *)vrq->vring.used - (char *)vrq->vring.desc);
+}
+
+unsigned int virtqueue_vring_get_num(struct virtqueue *vq)
+{
+       struct virtqueue_vring *vrq = NULL;
+
+       UK_ASSERT(vq);
+
+       vrq = to_virtqueue_vring(vq);
+       return vrq->vring.num;
+}
+
 int virtqueue_buffer_dequeue(struct virtqueue *vq, void **cookie, __u32 *len)
 {
        struct virtqueue_vring *vrq = NULL;
-- 
2.17.1