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f7f510ec RR |
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 | */ | |
bb347d98 | 19 | |
f7f510ec RR |
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> | |
c22405c9 | 26 | #include <linux/module.h> |
f7f510ec | 27 | |
08e53fbd AK |
28 | |
29 | struct virtrng_info { | |
30 | struct virtio_device *vdev; | |
31 | struct hwrng hwrng; | |
32 | struct virtqueue *vq; | |
33 | unsigned int data_avail; | |
34 | struct completion have_data; | |
35 | bool busy; | |
36 | }; | |
f7f510ec RR |
37 | |
38 | static void random_recv_done(struct virtqueue *vq) | |
39 | { | |
08e53fbd AK |
40 | struct virtrng_info *vi = vq->vdev->priv; |
41 | ||
e5b89542 | 42 | /* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */ |
08e53fbd | 43 | if (!virtqueue_get_buf(vi->vq, &vi->data_avail)) |
e5b89542 | 44 | return; |
f7f510ec | 45 | |
08e53fbd | 46 | complete(&vi->have_data); |
f7f510ec RR |
47 | } |
48 | ||
bb347d98 | 49 | /* The host will fill any buffer we give it with sweet, sweet randomness. */ |
08e53fbd | 50 | static void register_buffer(struct virtrng_info *vi, u8 *buf, size_t size) |
f7f510ec RR |
51 | { |
52 | struct scatterlist sg; | |
53 | ||
bb347d98 IM |
54 | sg_init_one(&sg, buf, size); |
55 | ||
f7f510ec | 56 | /* There should always be room for one buffer. */ |
08e53fbd | 57 | virtqueue_add_inbuf(vi->vq, &sg, 1, buf, GFP_KERNEL); |
bb347d98 | 58 | |
08e53fbd | 59 | virtqueue_kick(vi->vq); |
f7f510ec RR |
60 | } |
61 | ||
bb347d98 | 62 | static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) |
f7f510ec | 63 | { |
cc8744e1 | 64 | int ret; |
08e53fbd | 65 | struct virtrng_info *vi = (struct virtrng_info *)rng->priv; |
f7f510ec | 66 | |
08e53fbd AK |
67 | if (!vi->busy) { |
68 | vi->busy = true; | |
69 | init_completion(&vi->have_data); | |
70 | register_buffer(vi, buf, size); | |
bb347d98 IM |
71 | } |
72 | ||
f7f510ec RR |
73 | if (!wait) |
74 | return 0; | |
75 | ||
08e53fbd | 76 | ret = wait_for_completion_killable(&vi->have_data); |
cc8744e1 AS |
77 | if (ret < 0) |
78 | return ret; | |
594de1dd | 79 | |
08e53fbd | 80 | vi->busy = false; |
594de1dd | 81 | |
08e53fbd | 82 | return vi->data_avail; |
f7f510ec RR |
83 | } |
84 | ||
bb347d98 | 85 | static void virtio_cleanup(struct hwrng *rng) |
f7f510ec | 86 | { |
08e53fbd | 87 | struct virtrng_info *vi = (struct virtrng_info *)rng->priv; |
bb347d98 | 88 | |
08e53fbd AK |
89 | if (vi->busy) |
90 | wait_for_completion(&vi->have_data); | |
91 | } | |
f7f510ec | 92 | |
178d855e | 93 | static int probe_common(struct virtio_device *vdev) |
f7f510ec | 94 | { |
08e53fbd AK |
95 | int err, i; |
96 | struct virtrng_info *vi = NULL; | |
97 | ||
98 | vi = kmalloc(sizeof(struct virtrng_info), GFP_KERNEL); | |
99 | vi->hwrng.name = kmalloc(40, GFP_KERNEL); | |
100 | init_completion(&vi->have_data); | |
101 | ||
102 | vi->hwrng.read = virtio_read; | |
103 | vi->hwrng.cleanup = virtio_cleanup; | |
104 | vi->hwrng.priv = (unsigned long)vi; | |
105 | vdev->priv = vi; | |
f7f510ec RR |
106 | |
107 | /* We expect a single virtqueue. */ | |
08e53fbd AK |
108 | vi->vq = virtio_find_single_vq(vdev, random_recv_done, "input"); |
109 | if (IS_ERR(vi->vq)) { | |
110 | err = PTR_ERR(vi->vq); | |
111 | kfree(vi->hwrng.name); | |
112 | vi->vq = NULL; | |
113 | kfree(vi); | |
114 | vi = NULL; | |
e84e7a56 AS |
115 | return err; |
116 | } | |
f7f510ec | 117 | |
08e53fbd AK |
118 | i = 0; |
119 | do { | |
120 | sprintf(vi->hwrng.name, "virtio_rng.%d", i++); | |
121 | err = hwrng_register(&vi->hwrng); | |
122 | } while (err == -EEXIST); | |
123 | ||
f7f510ec | 124 | if (err) { |
d2a7ddda | 125 | vdev->config->del_vqs(vdev); |
08e53fbd AK |
126 | kfree(vi->hwrng.name); |
127 | vi->vq = NULL; | |
128 | kfree(vi); | |
129 | vi = NULL; | |
f7f510ec RR |
130 | return err; |
131 | } | |
132 | ||
f7f510ec RR |
133 | return 0; |
134 | } | |
135 | ||
178d855e | 136 | static void remove_common(struct virtio_device *vdev) |
f7f510ec | 137 | { |
08e53fbd | 138 | struct virtrng_info *vi = vdev->priv; |
f7f510ec | 139 | vdev->config->reset(vdev); |
08e53fbd AK |
140 | vi->busy = false; |
141 | hwrng_unregister(&vi->hwrng); | |
d2a7ddda | 142 | vdev->config->del_vqs(vdev); |
08e53fbd AK |
143 | kfree(vi->hwrng.name); |
144 | vi->vq = NULL; | |
145 | kfree(vi); | |
146 | vi = NULL; | |
f7f510ec RR |
147 | } |
148 | ||
178d855e AS |
149 | static int virtrng_probe(struct virtio_device *vdev) |
150 | { | |
151 | return probe_common(vdev); | |
152 | } | |
153 | ||
39af33fc | 154 | static void virtrng_remove(struct virtio_device *vdev) |
178d855e AS |
155 | { |
156 | remove_common(vdev); | |
157 | } | |
158 | ||
89107000 | 159 | #ifdef CONFIG_PM_SLEEP |
0bc1a2ef AS |
160 | static int virtrng_freeze(struct virtio_device *vdev) |
161 | { | |
162 | remove_common(vdev); | |
163 | return 0; | |
164 | } | |
165 | ||
166 | static int virtrng_restore(struct virtio_device *vdev) | |
167 | { | |
168 | return probe_common(vdev); | |
169 | } | |
170 | #endif | |
171 | ||
f7f510ec RR |
172 | static struct virtio_device_id id_table[] = { |
173 | { VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID }, | |
174 | { 0 }, | |
175 | }; | |
176 | ||
d817cd52 | 177 | static struct virtio_driver virtio_rng_driver = { |
f7f510ec RR |
178 | .driver.name = KBUILD_MODNAME, |
179 | .driver.owner = THIS_MODULE, | |
180 | .id_table = id_table, | |
181 | .probe = virtrng_probe, | |
bcd2982a | 182 | .remove = virtrng_remove, |
89107000 | 183 | #ifdef CONFIG_PM_SLEEP |
0bc1a2ef AS |
184 | .freeze = virtrng_freeze, |
185 | .restore = virtrng_restore, | |
186 | #endif | |
f7f510ec RR |
187 | }; |
188 | ||
b2a17029 | 189 | module_virtio_driver(virtio_rng_driver); |
f7f510ec RR |
190 | MODULE_DEVICE_TABLE(virtio, id_table); |
191 | MODULE_DESCRIPTION("Virtio random number driver"); | |
192 | MODULE_LICENSE("GPL"); |