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- /* SPDX-License-Identifier: BSD-3-Clause */
- /*
- * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
- * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
- *
- * From Linux kernel include/uapi/linux/virtio_ring.h
- */
- #ifndef _LINUX_VIRTIO_RING_H
- #define _LINUX_VIRTIO_RING_H
- #include <virtio_types.h>
- /* This marks a buffer as continuing via the next field */
- #define VRING_DESC_F_NEXT 1
- /* This marks a buffer as write-only (otherwise read-only) */
- #define VRING_DESC_F_WRITE 2
- /* This means the buffer contains a list of buffer descriptors */
- #define VRING_DESC_F_INDIRECT 4
- /*
- * The Host uses this in used->flags to advise the Guest: don't kick me when
- * you add a buffer. It's unreliable, so it's simply an optimization. Guest
- * will still kick if it's out of buffers.
- */
- #define VRING_USED_F_NO_NOTIFY 1
- /*
- * The Guest uses this in avail->flags to advise the Host: don't interrupt me
- * when you consume a buffer. It's unreliable, so it's simply an optimization.
- */
- #define VRING_AVAIL_F_NO_INTERRUPT 1
- /* We support indirect buffer descriptors */
- #define VIRTIO_RING_F_INDIRECT_DESC 28
- /*
- * The Guest publishes the used index for which it expects an interrupt
- * at the end of the avail ring. Host should ignore the avail->flags field.
- *
- * The Host publishes the avail index for which it expects a kick
- * at the end of the used ring. Guest should ignore the used->flags field.
- */
- #define VIRTIO_RING_F_EVENT_IDX 29
- /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */
- struct vring_desc {
- /* Address (guest-physical) */
- __virtio64 addr;
- /* Length */
- __virtio32 len;
- /* The flags as indicated above */
- __virtio16 flags;
- /* We chain unused descriptors via this, too */
- __virtio16 next;
- };
- struct vring_avail {
- __virtio16 flags;
- __virtio16 idx;
- __virtio16 ring[];
- };
- struct vring_used_elem {
- /* Index of start of used descriptor chain */
- __virtio32 id;
- /* Total length of the descriptor chain which was used (written to) */
- __virtio32 len;
- };
- struct vring_used {
- __virtio16 flags;
- __virtio16 idx;
- struct vring_used_elem ring[];
- };
- struct vring {
- unsigned int num;
- struct vring_desc *desc;
- struct vring_avail *avail;
- struct vring_used *used;
- };
- /**
- * virtqueue - a queue to register buffers for sending or receiving.
- *
- * @list: the chain of virtqueues for this device
- * @vdev: the virtio device this queue was created for
- * @index: the zero-based ordinal number for this queue
- * @num_free: number of elements we expect to be able to fit
- * @vring: actual memory layout for this queue
- * @event: host publishes avail event idx
- * @free_head: head of free buffer list
- * @num_added: number we've added since last sync
- * @last_used_idx: last used index we've seen
- * @avail_flags_shadow: last written value to avail->flags
- * @avail_idx_shadow: last written value to avail->idx in guest byte order
- */
- struct virtqueue {
- struct list_head list;
- struct udevice *vdev;
- unsigned int index;
- unsigned int num_free;
- struct vring vring;
- bool event;
- unsigned int free_head;
- unsigned int num_added;
- u16 last_used_idx;
- u16 avail_flags_shadow;
- u16 avail_idx_shadow;
- };
- /*
- * Alignment requirements for vring elements.
- * When using pre-virtio 1.0 layout, these fall out naturally.
- */
- #define VRING_AVAIL_ALIGN_SIZE 2
- #define VRING_USED_ALIGN_SIZE 4
- #define VRING_DESC_ALIGN_SIZE 16
- /*
- * We publish the used event index at the end of the available ring,
- * and vice versa. They are at the end for backwards compatibility.
- */
- #define vring_used_event(vr) ((vr)->avail->ring[(vr)->num])
- #define vring_avail_event(vr) (*(__virtio16 *)&(vr)->used->ring[(vr)->num])
- static inline void vring_init(struct vring *vr, unsigned int num, void *p,
- unsigned long align)
- {
- vr->num = num;
- vr->desc = p;
- vr->avail = p + num * sizeof(struct vring_desc);
- vr->used = (void *)(((uintptr_t)&vr->avail->ring[num] +
- sizeof(__virtio16) + align - 1) & ~(align - 1));
- }
- static inline unsigned int vring_size(unsigned int num, unsigned long align)
- {
- return ((sizeof(struct vring_desc) * num +
- sizeof(__virtio16) * (3 + num) + align - 1) & ~(align - 1)) +
- sizeof(__virtio16) * 3 + sizeof(struct vring_used_elem) * num;
- }
- /*
- * The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX.
- * Assuming a given event_idx value from the other side, if we have just
- * incremented index from old to new_idx, should we trigger an event?
- */
- static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old)
- {
- /*
- * Note: Xen has similar logic for notification hold-off
- * in include/xen/interface/io/ring.h with req_event and req_prod
- * corresponding to event_idx + 1 and new_idx respectively.
- * Note also that req_event and req_prod in Xen start at 1,
- * event indexes in virtio start at 0.
- */
- return (__u16)(new_idx - event_idx - 1) < (__u16)(new_idx - old);
- }
- struct virtio_sg;
- /**
- * virtqueue_add - expose buffers to other end
- *
- * @vq: the struct virtqueue we're talking about
- * @sgs: array of terminated scatterlists
- * @out_sgs: the number of scatterlists readable by other side
- * @in_sgs: the number of scatterlists which are writable
- * (after readable ones)
- *
- * Caller must ensure we don't call this with other virtqueue operations
- * at the same time (except where noted).
- *
- * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
- */
- int virtqueue_add(struct virtqueue *vq, struct virtio_sg *sgs[],
- unsigned int out_sgs, unsigned int in_sgs);
- /**
- * virtqueue_kick - update after add_buf
- *
- * @vq: the struct virtqueue
- *
- * After one or more virtqueue_add() calls, invoke this to kick
- * the other side.
- *
- * Caller must ensure we don't call this with other virtqueue
- * operations at the same time (except where noted).
- */
- void virtqueue_kick(struct virtqueue *vq);
- /**
- * virtqueue_get_buf - get the next used buffer
- *
- * @vq: the struct virtqueue we're talking about
- * @len: the length written into the buffer
- *
- * If the device wrote data into the buffer, @len will be set to the
- * amount written. This means you don't need to clear the buffer
- * beforehand to ensure there's no data leakage in the case of short
- * writes.
- *
- * Caller must ensure we don't call this with other virtqueue
- * operations at the same time (except where noted).
- *
- * Returns NULL if there are no used buffers, or the memory buffer
- * handed to virtqueue_add_*().
- */
- void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
- /**
- * vring_create_virtqueue - create a virtqueue for a virtio device
- *
- * @index: the index of the queue
- * @num: number of elements of the queue
- * @vring_align:the alignment requirement of the descriptor ring
- * @udev: the virtio transport udevice
- * @return: the virtqueue pointer or NULL if failed
- *
- * This creates a virtqueue and allocates the descriptor ring for a virtio
- * device. The caller should query virtqueue_get_ring_size() to learn the
- * actual size of the ring.
- *
- * This API is supposed to be called by the virtio transport driver in the
- * virtio find_vqs() uclass method.
- */
- struct virtqueue *vring_create_virtqueue(unsigned int index, unsigned int num,
- unsigned int vring_align,
- struct udevice *udev);
- /**
- * vring_del_virtqueue - destroy a virtqueue
- *
- * @vq: the struct virtqueue we're talking about
- *
- * This destroys a virtqueue. If created with vring_create_virtqueue(),
- * this also frees the descriptor ring.
- *
- * This API is supposed to be called by the virtio transport driver in the
- * virtio del_vqs() uclass method.
- */
- void vring_del_virtqueue(struct virtqueue *vq);
- /**
- * virtqueue_get_vring_size - get the size of the virtqueue's vring
- *
- * @vq: the struct virtqueue containing the vring of interest
- * @return: the size of the vring in a virtqueue.
- */
- unsigned int virtqueue_get_vring_size(struct virtqueue *vq);
- /**
- * virtqueue_get_desc_addr - get the vring descriptor table address
- *
- * @vq: the struct virtqueue containing the vring of interest
- * @return: the descriptor table address of the vring in a virtqueue.
- */
- ulong virtqueue_get_desc_addr(struct virtqueue *vq);
- /**
- * virtqueue_get_avail_addr - get the vring available ring address
- *
- * @vq: the struct virtqueue containing the vring of interest
- * @return: the available ring address of the vring in a virtqueue.
- */
- ulong virtqueue_get_avail_addr(struct virtqueue *vq);
- /**
- * virtqueue_get_used_addr - get the vring used ring address
- *
- * @vq: the struct virtqueue containing the vring of interest
- * @return: the used ring address of the vring in a virtqueue.
- */
- ulong virtqueue_get_used_addr(struct virtqueue *vq);
- /**
- * virtqueue_poll - query pending used buffers
- *
- * @vq: the struct virtqueue we're talking about
- * @last_used_idx: virtqueue last used index
- *
- * Returns "true" if there are pending used buffers in the queue.
- */
- bool virtqueue_poll(struct virtqueue *vq, u16 last_used_idx);
- /**
- * virtqueue_dump - dump the virtqueue for debugging
- *
- * @vq: the struct virtqueue we're talking about
- *
- * Caller must ensure we don't call this with other virtqueue operations
- * at the same time (except where noted).
- */
- void virtqueue_dump(struct virtqueue *vq);
- /*
- * Barriers in virtio are tricky. Since we are not in a hyperviosr/guest
- * scenario, having these as nops is enough to work as expected.
- */
- static inline void virtio_mb(void)
- {
- }
- static inline void virtio_rmb(void)
- {
- }
- static inline void virtio_wmb(void)
- {
- }
- static inline void virtio_store_mb(__virtio16 *p, __virtio16 v)
- {
- WRITE_ONCE(*p, v);
- }
- #endif /* _LINUX_VIRTIO_RING_H */
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