1/* virtio-pci.c - virtio ring management
2 *
3 * (c) Copyright 2008 Bull S.A.S.
4 *
5 *  Author: Laurent Vivier <Laurent.Vivier@bull.net>
6 *
7 *  some parts from Linux Virtio Ring
8 *
9 *  Copyright Rusty Russell IBM Corporation 2007
10 *
11 * This work is licensed under the terms of the GNU GPL, version 2 or later.
12 * See the COPYING file in the top-level directory.
13 *
14 *
15 */
16
17#include "etherboot.h"
18#include "gpxe/io.h"
19#include "gpxe/virtio-ring.h"
20#include "gpxe/virtio-pci.h"
21
22#define BUG() do { \
23   printf("BUG: failure at %s:%d/%s()!\n", \
24          __FILE__, __LINE__, __FUNCTION__); \
25   while(1); \
26} while (0)
27#define BUG_ON(condition) do { if (condition) BUG(); } while (0)
28
29/*
30 * vring_free
31 *
32 * put at the begin of the free list the current desc[head]
33 */
34
35void vring_detach(struct vring_virtqueue *vq, unsigned int head)
36{
37   struct vring *vr = &vq->vring;
38   unsigned int i;
39
40   /* find end of given descriptor */
41
42   i = head;
43   while (vr->desc[i].flags & VRING_DESC_F_NEXT)
44           i = vr->desc[i].next;
45
46   /* link it with free list and point to it */
47
48   vr->desc[i].next = vq->free_head;
49   wmb();
50   vq->free_head = head;
51}
52
53/*
54 * vring_get_buf
55 *
56 * get a buffer from the used list
57 *
58 */
59
60int vring_get_buf(struct vring_virtqueue *vq, unsigned int *len)
61{
62   struct vring *vr = &vq->vring;
63   struct vring_used_elem *elem;
64   u32 id;
65   int ret;
66
67   BUG_ON(!vring_more_used(vq));
68
69   elem = &vr->used->ring[vq->last_used_idx % vr->num];
70   wmb();
71   id = elem->id;
72   if (len != NULL)
73           *len = elem->len;
74
75   ret = vq->vdata[id];
76
77   vring_detach(vq, id);
78
79   vq->last_used_idx++;
80
81   return ret;
82}
83
84void vring_add_buf(struct vring_virtqueue *vq,
85		   struct vring_list list[],
86		   unsigned int out, unsigned int in,
87		   int index, int num_added)
88{
89   struct vring *vr = &vq->vring;
90   int i, avail, head, prev;
91
92   BUG_ON(out + in == 0);
93
94   prev = 0;
95   head = vq->free_head;
96   for (i = head; out; i = vr->desc[i].next, out--) {
97
98           vr->desc[i].flags = VRING_DESC_F_NEXT;
99           vr->desc[i].addr = (u64)virt_to_phys(list->addr);
100           vr->desc[i].len = list->length;
101           prev = i;
102           list++;
103   }
104   for ( ; in; i = vr->desc[i].next, in--) {
105
106           vr->desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE;
107           vr->desc[i].addr = (u64)virt_to_phys(list->addr);
108           vr->desc[i].len = list->length;
109           prev = i;
110           list++;
111   }
112   vr->desc[prev].flags &= ~VRING_DESC_F_NEXT;
113
114   vq->free_head = i;
115
116   vq->vdata[head] = index;
117
118   avail = (vr->avail->idx + num_added) % vr->num;
119   vr->avail->ring[avail] = head;
120   wmb();
121}
122
123void vring_kick(unsigned int ioaddr, struct vring_virtqueue *vq, int num_added)
124{
125   struct vring *vr = &vq->vring;
126
127   wmb();
128   vr->avail->idx += num_added;
129
130   mb();
131   if (!(vr->used->flags & VRING_USED_F_NO_NOTIFY))
132           vp_notify(ioaddr, vq->queue_index);
133}
134
135