Loading...
1/*
2 * Randomness driver for virtio
3 * Copyright (C) 2007, 2008 Rusty Russell IBM Corporation
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18 */
19
20#include <linux/err.h>
21#include <linux/hw_random.h>
22#include <linux/scatterlist.h>
23#include <linux/spinlock.h>
24#include <linux/virtio.h>
25#include <linux/virtio_rng.h>
26
27static struct virtqueue *vq;
28static unsigned int data_avail;
29static DECLARE_COMPLETION(have_data);
30static bool busy;
31
32static void random_recv_done(struct virtqueue *vq)
33{
34 /* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */
35 if (!virtqueue_get_buf(vq, &data_avail))
36 return;
37
38 complete(&have_data);
39}
40
41/* The host will fill any buffer we give it with sweet, sweet randomness. */
42static void register_buffer(u8 *buf, size_t size)
43{
44 struct scatterlist sg;
45
46 sg_init_one(&sg, buf, size);
47
48 /* There should always be room for one buffer. */
49 if (virtqueue_add_buf(vq, &sg, 0, 1, buf) < 0)
50 BUG();
51
52 virtqueue_kick(vq);
53}
54
55static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait)
56{
57
58 if (!busy) {
59 busy = true;
60 init_completion(&have_data);
61 register_buffer(buf, size);
62 }
63
64 if (!wait)
65 return 0;
66
67 wait_for_completion(&have_data);
68
69 busy = false;
70
71 return data_avail;
72}
73
74static void virtio_cleanup(struct hwrng *rng)
75{
76 if (busy)
77 wait_for_completion(&have_data);
78}
79
80
81static struct hwrng virtio_hwrng = {
82 .name = "virtio",
83 .cleanup = virtio_cleanup,
84 .read = virtio_read,
85};
86
87static int virtrng_probe(struct virtio_device *vdev)
88{
89 int err;
90
91 /* We expect a single virtqueue. */
92 vq = virtio_find_single_vq(vdev, random_recv_done, "input");
93 if (IS_ERR(vq))
94 return PTR_ERR(vq);
95
96 err = hwrng_register(&virtio_hwrng);
97 if (err) {
98 vdev->config->del_vqs(vdev);
99 return err;
100 }
101
102 return 0;
103}
104
105static void __devexit virtrng_remove(struct virtio_device *vdev)
106{
107 vdev->config->reset(vdev);
108 hwrng_unregister(&virtio_hwrng);
109 vdev->config->del_vqs(vdev);
110}
111
112static struct virtio_device_id id_table[] = {
113 { VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID },
114 { 0 },
115};
116
117static struct virtio_driver virtio_rng_driver = {
118 .driver.name = KBUILD_MODNAME,
119 .driver.owner = THIS_MODULE,
120 .id_table = id_table,
121 .probe = virtrng_probe,
122 .remove = __devexit_p(virtrng_remove),
123};
124
125static int __init init(void)
126{
127 return register_virtio_driver(&virtio_rng_driver);
128}
129
130static void __exit fini(void)
131{
132 unregister_virtio_driver(&virtio_rng_driver);
133}
134module_init(init);
135module_exit(fini);
136
137MODULE_DEVICE_TABLE(virtio, id_table);
138MODULE_DESCRIPTION("Virtio random number driver");
139MODULE_LICENSE("GPL");
1/*
2 * Randomness driver for virtio
3 * Copyright (C) 2007, 2008 Rusty Russell IBM Corporation
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18 */
19
20#include <linux/err.h>
21#include <linux/hw_random.h>
22#include <linux/scatterlist.h>
23#include <linux/spinlock.h>
24#include <linux/virtio.h>
25#include <linux/virtio_rng.h>
26#include <linux/module.h>
27
28static struct virtqueue *vq;
29static unsigned int data_avail;
30static DECLARE_COMPLETION(have_data);
31static bool busy;
32
33static void random_recv_done(struct virtqueue *vq)
34{
35 /* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */
36 if (!virtqueue_get_buf(vq, &data_avail))
37 return;
38
39 complete(&have_data);
40}
41
42/* The host will fill any buffer we give it with sweet, sweet randomness. */
43static void register_buffer(u8 *buf, size_t size)
44{
45 struct scatterlist sg;
46
47 sg_init_one(&sg, buf, size);
48
49 /* There should always be room for one buffer. */
50 virtqueue_add_inbuf(vq, &sg, 1, buf, GFP_KERNEL);
51
52 virtqueue_kick(vq);
53}
54
55static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait)
56{
57 int ret;
58
59 if (!busy) {
60 busy = true;
61 init_completion(&have_data);
62 register_buffer(buf, size);
63 }
64
65 if (!wait)
66 return 0;
67
68 ret = wait_for_completion_killable(&have_data);
69 if (ret < 0)
70 return ret;
71
72 busy = false;
73
74 return data_avail;
75}
76
77static void virtio_cleanup(struct hwrng *rng)
78{
79 if (busy)
80 wait_for_completion(&have_data);
81}
82
83
84static struct hwrng virtio_hwrng = {
85 .name = "virtio",
86 .cleanup = virtio_cleanup,
87 .read = virtio_read,
88};
89
90static int probe_common(struct virtio_device *vdev)
91{
92 int err;
93
94 if (vq) {
95 /* We only support one device for now */
96 return -EBUSY;
97 }
98 /* We expect a single virtqueue. */
99 vq = virtio_find_single_vq(vdev, random_recv_done, "input");
100 if (IS_ERR(vq)) {
101 err = PTR_ERR(vq);
102 vq = NULL;
103 return err;
104 }
105
106 err = hwrng_register(&virtio_hwrng);
107 if (err) {
108 vdev->config->del_vqs(vdev);
109 vq = NULL;
110 return err;
111 }
112
113 return 0;
114}
115
116static void remove_common(struct virtio_device *vdev)
117{
118 vdev->config->reset(vdev);
119 busy = false;
120 hwrng_unregister(&virtio_hwrng);
121 vdev->config->del_vqs(vdev);
122 vq = NULL;
123}
124
125static int virtrng_probe(struct virtio_device *vdev)
126{
127 return probe_common(vdev);
128}
129
130static void virtrng_remove(struct virtio_device *vdev)
131{
132 remove_common(vdev);
133}
134
135#ifdef CONFIG_PM_SLEEP
136static int virtrng_freeze(struct virtio_device *vdev)
137{
138 remove_common(vdev);
139 return 0;
140}
141
142static int virtrng_restore(struct virtio_device *vdev)
143{
144 return probe_common(vdev);
145}
146#endif
147
148static struct virtio_device_id id_table[] = {
149 { VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID },
150 { 0 },
151};
152
153static struct virtio_driver virtio_rng_driver = {
154 .driver.name = KBUILD_MODNAME,
155 .driver.owner = THIS_MODULE,
156 .id_table = id_table,
157 .probe = virtrng_probe,
158 .remove = virtrng_remove,
159#ifdef CONFIG_PM_SLEEP
160 .freeze = virtrng_freeze,
161 .restore = virtrng_restore,
162#endif
163};
164
165module_virtio_driver(virtio_rng_driver);
166MODULE_DEVICE_TABLE(virtio, id_table);
167MODULE_DESCRIPTION("Virtio random number driver");
168MODULE_LICENSE("GPL");