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git.ipfire.org Git - thirdparty/u-boot.git/blob - include/virtio_ring.h
1 /* SPDX-License-Identifier: BSD-3-Clause */
3 * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
4 * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
6 * From Linux kernel include/uapi/linux/virtio_ring.h
9 #ifndef _LINUX_VIRTIO_RING_H
10 #define _LINUX_VIRTIO_RING_H
12 #include <virtio_types.h>
14 /* This marks a buffer as continuing via the next field */
15 #define VRING_DESC_F_NEXT 1
16 /* This marks a buffer as write-only (otherwise read-only) */
17 #define VRING_DESC_F_WRITE 2
18 /* This means the buffer contains a list of buffer descriptors */
19 #define VRING_DESC_F_INDIRECT 4
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
24 * will still kick if it's out of buffers.
26 #define VRING_USED_F_NO_NOTIFY 1
29 * The Guest uses this in avail->flags to advise the Host: don't interrupt me
30 * when you consume a buffer. It's unreliable, so it's simply an optimization.
32 #define VRING_AVAIL_F_NO_INTERRUPT 1
34 /* We support indirect buffer descriptors */
35 #define VIRTIO_RING_F_INDIRECT_DESC 28
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.
41 * The Host publishes the avail index for which it expects a kick
42 * at the end of the used ring. Guest should ignore the used->flags field.
44 #define VIRTIO_RING_F_EVENT_IDX 29
46 /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */
48 /* Address (guest-physical) */
52 /* The flags as indicated above */
54 /* We chain unused descriptors via this, too */
58 /* Shadow of struct vring_desc in guest byte order. */
59 struct vring_desc_shadow
{
64 /* Metadata about the descriptor. */
74 struct vring_used_elem
{
75 /* Index of start of used descriptor chain */
77 /* Total length of the descriptor chain which was used (written to) */
84 struct vring_used_elem ring
[];
90 struct vring_desc
*desc
;
91 struct vring_avail
*avail
;
92 struct vring_used
*used
;
96 * virtqueue - a queue to register buffers for sending or receiving.
98 * @list: the chain of virtqueues for this device
99 * @vdev: the virtio device this queue was created for
100 * @index: the zero-based ordinal number for this queue
101 * @num_free: number of elements we expect to be able to fit
102 * @vring: actual memory layout for this queue
103 * @vring_desc_shadow: guest-only copy of descriptors
104 * @event: host publishes avail event idx
105 * @free_head: head of free buffer list
106 * @num_added: number we've added since last sync
107 * @last_used_idx: last used index we've seen
108 * @avail_flags_shadow: last written value to avail->flags
109 * @avail_idx_shadow: last written value to avail->idx in guest byte order
112 struct list_head list
;
113 struct udevice
*vdev
;
115 unsigned int num_free
;
117 struct vring_desc_shadow
*vring_desc_shadow
;
119 unsigned int free_head
;
120 unsigned int num_added
;
122 u16 avail_flags_shadow
;
123 u16 avail_idx_shadow
;
127 * Alignment requirements for vring elements.
128 * When using pre-virtio 1.0 layout, these fall out naturally.
130 #define VRING_AVAIL_ALIGN_SIZE 2
131 #define VRING_USED_ALIGN_SIZE 4
132 #define VRING_DESC_ALIGN_SIZE 16
135 * We publish the used event index at the end of the available ring,
136 * and vice versa. They are at the end for backwards compatibility.
138 #define vring_used_event(vr) ((vr)->avail->ring[(vr)->num])
139 #define vring_avail_event(vr) (*(__virtio16 *)&(vr)->used->ring[(vr)->num])
141 static inline unsigned int vring_size(unsigned int num
, unsigned long align
)
143 return ((sizeof(struct vring_desc
) * num
+
144 sizeof(__virtio16
) * (3 + num
) + align
- 1) & ~(align
- 1)) +
145 sizeof(__virtio16
) * 3 + sizeof(struct vring_used_elem
) * num
;
148 static inline void vring_init(struct vring
*vr
, unsigned int num
, void *p
,
152 vr
->size
= vring_size(num
, align
);
154 vr
->avail
= p
+ num
* sizeof(struct vring_desc
);
155 vr
->used
= (void *)(((uintptr_t)&vr
->avail
->ring
[num
] +
156 sizeof(__virtio16
) + align
- 1) & ~(align
- 1));
160 * The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX.
161 * Assuming a given event_idx value from the other side, if we have just
162 * incremented index from old to new_idx, should we trigger an event?
164 static inline int vring_need_event(__u16 event_idx
, __u16 new_idx
, __u16 old
)
167 * Note: Xen has similar logic for notification hold-off
168 * in include/xen/interface/io/ring.h with req_event and req_prod
169 * corresponding to event_idx + 1 and new_idx respectively.
170 * Note also that req_event and req_prod in Xen start at 1,
171 * event indexes in virtio start at 0.
173 return (__u16
)(new_idx
- event_idx
- 1) < (__u16
)(new_idx
- old
);
179 * virtqueue_add - expose buffers to other end
181 * @vq: the struct virtqueue we're talking about
182 * @sgs: array of terminated scatterlists
183 * @out_sgs: the number of scatterlists readable by other side
184 * @in_sgs: the number of scatterlists which are writable
185 * (after readable ones)
187 * Caller must ensure we don't call this with other virtqueue operations
188 * at the same time (except where noted).
190 * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
192 int virtqueue_add(struct virtqueue
*vq
, struct virtio_sg
*sgs
[],
193 unsigned int out_sgs
, unsigned int in_sgs
);
196 * virtqueue_kick - update after add_buf
198 * @vq: the struct virtqueue
200 * After one or more virtqueue_add() calls, invoke this to kick
203 * Caller must ensure we don't call this with other virtqueue
204 * operations at the same time (except where noted).
206 void virtqueue_kick(struct virtqueue
*vq
);
209 * virtqueue_get_buf - get the next used buffer
211 * @vq: the struct virtqueue we're talking about
212 * @len: the length written into the buffer
214 * If the device wrote data into the buffer, @len will be set to the
215 * amount written. This means you don't need to clear the buffer
216 * beforehand to ensure there's no data leakage in the case of short
219 * Caller must ensure we don't call this with other virtqueue
220 * operations at the same time (except where noted).
222 * Returns NULL if there are no used buffers, or the memory buffer
223 * handed to virtqueue_add_*().
225 void *virtqueue_get_buf(struct virtqueue
*vq
, unsigned int *len
);
228 * vring_create_virtqueue - create a virtqueue for a virtio device
230 * @index: the index of the queue
231 * @num: number of elements of the queue
232 * @vring_align:the alignment requirement of the descriptor ring
233 * @udev: the virtio transport udevice
234 * @return: the virtqueue pointer or NULL if failed
236 * This creates a virtqueue and allocates the descriptor ring for a virtio
237 * device. The caller should query virtqueue_get_ring_size() to learn the
238 * actual size of the ring.
240 * This API is supposed to be called by the virtio transport driver in the
241 * virtio find_vqs() uclass method.
243 struct virtqueue
*vring_create_virtqueue(unsigned int index
, unsigned int num
,
244 unsigned int vring_align
,
245 struct udevice
*udev
);
248 * vring_del_virtqueue - destroy a virtqueue
250 * @vq: the struct virtqueue we're talking about
252 * This destroys a virtqueue. If created with vring_create_virtqueue(),
253 * this also frees the descriptor ring.
255 * This API is supposed to be called by the virtio transport driver in the
256 * virtio del_vqs() uclass method.
258 void vring_del_virtqueue(struct virtqueue
*vq
);
261 * virtqueue_get_vring_size - get the size of the virtqueue's vring
263 * @vq: the struct virtqueue containing the vring of interest
264 * @return: the size of the vring in a virtqueue.
266 unsigned int virtqueue_get_vring_size(struct virtqueue
*vq
);
269 * virtqueue_get_desc_addr - get the vring descriptor table address
271 * @vq: the struct virtqueue containing the vring of interest
272 * @return: the descriptor table address of the vring in a virtqueue.
274 ulong
virtqueue_get_desc_addr(struct virtqueue
*vq
);
277 * virtqueue_get_avail_addr - get the vring available ring address
279 * @vq: the struct virtqueue containing the vring of interest
280 * @return: the available ring address of the vring in a virtqueue.
282 ulong
virtqueue_get_avail_addr(struct virtqueue
*vq
);
285 * virtqueue_get_used_addr - get the vring used ring address
287 * @vq: the struct virtqueue containing the vring of interest
288 * @return: the used ring address of the vring in a virtqueue.
290 ulong
virtqueue_get_used_addr(struct virtqueue
*vq
);
293 * virtqueue_poll - query pending used buffers
295 * @vq: the struct virtqueue we're talking about
296 * @last_used_idx: virtqueue last used index
298 * Returns "true" if there are pending used buffers in the queue.
300 bool virtqueue_poll(struct virtqueue
*vq
, u16 last_used_idx
);
303 * virtqueue_dump - dump the virtqueue for debugging
305 * @vq: the struct virtqueue we're talking about
307 * Caller must ensure we don't call this with other virtqueue operations
308 * at the same time (except where noted).
310 void virtqueue_dump(struct virtqueue
*vq
);
313 * Barriers in virtio are tricky. Since we are not in a hyperviosr/guest
314 * scenario, having these as nops is enough to work as expected.
317 static inline void virtio_mb(void)
321 static inline void virtio_rmb(void)
325 static inline void virtio_wmb(void)
329 static inline void virtio_store_mb(__virtio16
*p
, __virtio16 v
)
334 #endif /* _LINUX_VIRTIO_RING_H */