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 if (rsize > sg.length)
45 return -EIO;
46
47 memcpy(ptr, buf, rsize);
48 len -= rsize;
49 ptr += rsize;
50 }
51
52 return 0;
53 }
54
virtio_rng_bind(struct udevice * dev)55 static int virtio_rng_bind(struct udevice *dev)
56 {
57 struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(dev->parent);
58
59 /* Indicate what driver features we support */
60 virtio_driver_features_init(uc_priv, NULL, 0, NULL, 0);
61
62 return 0;
63 }
64
virtio_rng_probe(struct udevice * dev)65 static int virtio_rng_probe(struct udevice *dev)
66 {
67 struct virtio_rng_priv *priv = dev_get_priv(dev);
68 int ret;
69
70 ret = virtio_find_vqs(dev, 1, &priv->rng_vq);
71 if (ret < 0) {
72 debug("%s: virtio_find_vqs failed\n", __func__);
73 return ret;
74 }
75
76 return 0;
77 }
78
79 static const struct dm_rng_ops virtio_rng_ops = {
80 .read = virtio_rng_read,
81 };
82
83 U_BOOT_DRIVER(virtio_rng) = {
84 .name = VIRTIO_RNG_DRV_NAME,
85 .id = UCLASS_RNG,
86 .bind = virtio_rng_bind,
87 .probe = virtio_rng_probe,
88 .remove = virtio_reset,
89 .ops = &virtio_rng_ops,
90 .priv_auto = sizeof(struct virtio_rng_priv),
91 .flags = DM_FLAG_ACTIVE_DMA,
92 };
93