u-boot/include/virtio_ring.h

1 /* SPDX-License-Identifier: BSD-3-Clause */
16 /* This marks a buffer as write-only (otherwise read-only) */
22  * The Host uses this in used->flags to advise the Guest: don't kick me when
23  * you add a buffer. It's unreliable, so it's simply an optimization. Guest
29  * The Guest uses this in avail->flags to advise the Host: don't interrupt me
38  * The Guest publishes the used index for which it expects an interrupt
39  * at the end of the avail ring. Host should ignore the avail->flags field.
42  * at the end of the used ring. Guest should ignore the used->flags field.
48 	/* Address (guest-physical) */
85  * virtqueue - a queue to register buffers for sending or receiving.
89  * @index: the zero-based ordinal number for this queue
96  * @avail_flags_shadow: last written value to avail->flags
97  * @avail_idx_shadow: last written value to avail->idx in guest byte order
115  * When using pre-virtio 1.0 layout, these fall out naturally.
125 #define vring_used_event(vr)	((vr)->avail->ring[(vr)->num])
126 #define vring_avail_event(vr)	(*(__virtio16 *)&(vr)->used->ring[(vr)->num])
131 	vr->num = num;  in vring_init()
132 	vr->desc = p;  in vring_init()
133 	vr->avail = p + num * sizeof(struct vring_desc);  in vring_init()
134 	vr->used = (void *)(((uintptr_t)&vr->avail->ring[num] +  in vring_init()
135 		   sizeof(__virtio16) + align - 1) & ~(align - 1));  in vring_init()
141 		sizeof(__virtio16) * (3 + num)  + align - 1) & ~(align - 1)) +  in vring_size()
147  * Assuming a given event_idx value from the other side, if we have just
153 	 * Note: Xen has similar logic for notification hold-off  in vring_need_event()
159 	return (__u16)(new_idx - event_idx - 1) < (__u16)(new_idx - old);  in vring_need_event()
165  * virtqueue_add - expose buffers to other end
169  * @out_sgs:	the number of scatterlists readable by other side
182  * virtqueue_kick - update after add_buf
187  * the other side.
195  * virtqueue_get_buf - get the next used buffer
214  * vring_create_virtqueue - create a virtqueue for a virtio device
234  * vring_del_virtqueue - destroy a virtqueue
247  * virtqueue_get_vring_size - get the size of the virtqueue's vring
255  * virtqueue_get_desc_addr - get the vring descriptor table address
263  * virtqueue_get_avail_addr - get the vring available ring address
271  * virtqueue_get_used_addr - get the vring used ring address
279  * virtqueue_poll - query pending used buffers
289  * virtqueue_dump - dump the virtqueue for debugging
299  * Barriers in virtio are tricky. Since we are not in a hyperviosr/guest