1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (c) 2019, Linaro Limited
4 */
5
6 #include <common.h>
7 #include <dm.h>
8 #include <log.h>
9 #include <rng.h>
10 #include <virtio_types.h>
11 #include <virtio.h>
12 #include <virtio_ring.h>
13
14 #define BUFFER_SIZE 16UL
15
16 struct virtio_rng_priv {
17 struct virtqueue *rng_vq;
18 };
19
virtio_rng_read(struct udevice * dev,void * data,size_t len)20 static int virtio_rng_read(struct udevice *dev, void *data, size_t len)
21 {
22 int ret;
23 unsigned int rsize;
24 unsigned char buf[BUFFER_SIZE] __aligned(4);
25 unsigned char *ptr = data;
26 struct virtio_sg sg;
27 struct virtio_sg *sgs[1];
28 struct virtio_rng_priv *priv = dev_get_priv(dev);
29
30 while (len) {
31 sg.addr = buf;
32 sg.length = min(len, sizeof(buf));
33 sgs[0] = &sg;
34
35 ret = virtqueue_add(priv->rng_vq, sgs, 0, 1);
36 if (ret)
37 return ret;
38
39 virtqueue_kick(priv->rng_vq);
40
41 while (!virtqueue_get_buf(priv->rng_vq, &rsize))
42 ;
43
44 memcpy(ptr, buf, rsize);
45 len -= rsize;
46 ptr += rsize;
47 }
48
49 return 0;
50 }
51
virtio_rng_bind(struct udevice * dev)52 static int virtio_rng_bind(struct udevice *dev)
53 {
54 struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(dev->parent);
55
56 /* Indicate what driver features we support */
57 virtio_driver_features_init(uc_priv, NULL, 0, NULL, 0);
58
59 return 0;
60 }
61
virtio_rng_probe(struct udevice * dev)62 static int virtio_rng_probe(struct udevice *dev)
63 {
64 struct virtio_rng_priv *priv = dev_get_priv(dev);
65 int ret;
66
67 ret = virtio_find_vqs(dev, 1, &priv->rng_vq);
68 if (ret < 0) {
69 debug("%s: virtio_find_vqs failed\n", __func__);
70 return ret;
71 }
72
73 return 0;
74 }
75
76 static const struct dm_rng_ops virtio_rng_ops = {
77 .read = virtio_rng_read,
78 };
79
80 U_BOOT_DRIVER(virtio_rng) = {
81 .name = VIRTIO_RNG_DRV_NAME,
82 .id = UCLASS_RNG,
83 .bind = virtio_rng_bind,
84 .probe = virtio_rng_probe,
85 .remove = virtio_reset,
86 .ops = &virtio_rng_ops,
87 .priv_auto = sizeof(struct virtio_rng_priv),
88 .flags = DM_FLAG_ACTIVE_DMA,
89 };
90