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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 | |
a17597d3 | 28 | static DEFINE_IDA(rng_index_ida); |
08e53fbd AK |
29 | |
30 | struct virtrng_info { | |
08e53fbd AK |
31 | struct hwrng hwrng; |
32 | struct virtqueue *vq; | |
08e53fbd | 33 | struct completion have_data; |
a17597d3 | 34 | char name[25]; |
6062829f | 35 | unsigned int data_avail; |
a17597d3 | 36 | int index; |
6062829f | 37 | bool busy; |
5c062734 | 38 | bool hwrng_register_done; |
08e53fbd | 39 | }; |
f7f510ec | 40 | |
e052dbf5 | 41 | |
f7f510ec RR |
42 | static void random_recv_done(struct virtqueue *vq) |
43 | { | |
08e53fbd AK |
44 | struct virtrng_info *vi = vq->vdev->priv; |
45 | ||
e5b89542 | 46 | /* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */ |
08e53fbd | 47 | if (!virtqueue_get_buf(vi->vq, &vi->data_avail)) |
e5b89542 | 48 | return; |
f7f510ec | 49 | |
08e53fbd | 50 | complete(&vi->have_data); |
f7f510ec RR |
51 | } |
52 | ||
bb347d98 | 53 | /* The host will fill any buffer we give it with sweet, sweet randomness. */ |
08e53fbd | 54 | static void register_buffer(struct virtrng_info *vi, u8 *buf, size_t size) |
f7f510ec RR |
55 | { |
56 | struct scatterlist sg; | |
57 | ||
bb347d98 IM |
58 | sg_init_one(&sg, buf, size); |
59 | ||
f7f510ec | 60 | /* There should always be room for one buffer. */ |
08e53fbd | 61 | virtqueue_add_inbuf(vi->vq, &sg, 1, buf, GFP_KERNEL); |
bb347d98 | 62 | |
08e53fbd | 63 | virtqueue_kick(vi->vq); |
f7f510ec RR |
64 | } |
65 | ||
bb347d98 | 66 | static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) |
f7f510ec | 67 | { |
cc8744e1 | 68 | int ret; |
08e53fbd | 69 | struct virtrng_info *vi = (struct virtrng_info *)rng->priv; |
f7f510ec | 70 | |
08e53fbd AK |
71 | if (!vi->busy) { |
72 | vi->busy = true; | |
73 | init_completion(&vi->have_data); | |
74 | register_buffer(vi, buf, size); | |
bb347d98 IM |
75 | } |
76 | ||
f7f510ec RR |
77 | if (!wait) |
78 | return 0; | |
79 | ||
08e53fbd | 80 | ret = wait_for_completion_killable(&vi->have_data); |
cc8744e1 AS |
81 | if (ret < 0) |
82 | return ret; | |
594de1dd | 83 | |
08e53fbd | 84 | vi->busy = false; |
594de1dd | 85 | |
08e53fbd | 86 | return vi->data_avail; |
f7f510ec RR |
87 | } |
88 | ||
bb347d98 | 89 | static void virtio_cleanup(struct hwrng *rng) |
f7f510ec | 90 | { |
08e53fbd | 91 | struct virtrng_info *vi = (struct virtrng_info *)rng->priv; |
bb347d98 | 92 | |
08e53fbd AK |
93 | if (vi->busy) |
94 | wait_for_completion(&vi->have_data); | |
95 | } | |
f7f510ec | 96 | |
178d855e | 97 | static int probe_common(struct virtio_device *vdev) |
f7f510ec | 98 | { |
a17597d3 | 99 | int err, index; |
08e53fbd AK |
100 | struct virtrng_info *vi = NULL; |
101 | ||
e5d23a8c | 102 | vi = kzalloc(sizeof(struct virtrng_info), GFP_KERNEL); |
a17597d3 SL |
103 | if (!vi) |
104 | return -ENOMEM; | |
105 | ||
106 | vi->index = index = ida_simple_get(&rng_index_ida, 0, 0, GFP_KERNEL); | |
107 | if (index < 0) { | |
108 | kfree(vi); | |
109 | return index; | |
110 | } | |
111 | sprintf(vi->name, "virtio_rng.%d", index); | |
08e53fbd AK |
112 | init_completion(&vi->have_data); |
113 | ||
a17597d3 SL |
114 | vi->hwrng = (struct hwrng) { |
115 | .read = virtio_read, | |
116 | .cleanup = virtio_cleanup, | |
117 | .priv = (unsigned long)vi, | |
118 | .name = vi->name, | |
34679ec7 | 119 | .quality = 1000, |
a17597d3 | 120 | }; |
08e53fbd | 121 | vdev->priv = vi; |
f7f510ec RR |
122 | |
123 | /* We expect a single virtqueue. */ | |
08e53fbd AK |
124 | vi->vq = virtio_find_single_vq(vdev, random_recv_done, "input"); |
125 | if (IS_ERR(vi->vq)) { | |
126 | err = PTR_ERR(vi->vq); | |
08e53fbd AK |
127 | vi->vq = NULL; |
128 | kfree(vi); | |
a17597d3 | 129 | ida_simple_remove(&rng_index_ida, index); |
e84e7a56 AS |
130 | return err; |
131 | } | |
f7f510ec | 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; |
5c062734 | 139 | |
3856e548 AK |
140 | vi->data_avail = 0; |
141 | complete(&vi->have_data); | |
f7f510ec | 142 | vdev->config->reset(vdev); |
08e53fbd | 143 | vi->busy = false; |
5c062734 AS |
144 | if (vi->hwrng_register_done) |
145 | hwrng_unregister(&vi->hwrng); | |
d2a7ddda | 146 | vdev->config->del_vqs(vdev); |
a17597d3 | 147 | ida_simple_remove(&rng_index_ida, vi->index); |
08e53fbd | 148 | kfree(vi); |
f7f510ec RR |
149 | } |
150 | ||
178d855e AS |
151 | static int virtrng_probe(struct virtio_device *vdev) |
152 | { | |
153 | return probe_common(vdev); | |
154 | } | |
155 | ||
39af33fc | 156 | static void virtrng_remove(struct virtio_device *vdev) |
178d855e AS |
157 | { |
158 | remove_common(vdev); | |
159 | } | |
160 | ||
5c062734 AS |
161 | static void virtrng_scan(struct virtio_device *vdev) |
162 | { | |
163 | struct virtrng_info *vi = vdev->priv; | |
164 | int err; | |
165 | ||
166 | err = hwrng_register(&vi->hwrng); | |
167 | if (!err) | |
168 | vi->hwrng_register_done = true; | |
169 | } | |
170 | ||
89107000 | 171 | #ifdef CONFIG_PM_SLEEP |
0bc1a2ef AS |
172 | static int virtrng_freeze(struct virtio_device *vdev) |
173 | { | |
174 | remove_common(vdev); | |
175 | return 0; | |
176 | } | |
177 | ||
178 | static int virtrng_restore(struct virtio_device *vdev) | |
179 | { | |
180 | return probe_common(vdev); | |
181 | } | |
182 | #endif | |
183 | ||
f7f510ec RR |
184 | static struct virtio_device_id id_table[] = { |
185 | { VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID }, | |
186 | { 0 }, | |
187 | }; | |
188 | ||
d817cd52 | 189 | static struct virtio_driver virtio_rng_driver = { |
f7f510ec RR |
190 | .driver.name = KBUILD_MODNAME, |
191 | .driver.owner = THIS_MODULE, | |
192 | .id_table = id_table, | |
193 | .probe = virtrng_probe, | |
bcd2982a | 194 | .remove = virtrng_remove, |
5c062734 | 195 | .scan = virtrng_scan, |
89107000 | 196 | #ifdef CONFIG_PM_SLEEP |
0bc1a2ef AS |
197 | .freeze = virtrng_freeze, |
198 | .restore = virtrng_restore, | |
199 | #endif | |
f7f510ec RR |
200 | }; |
201 | ||
b2a17029 | 202 | module_virtio_driver(virtio_rng_driver); |
f7f510ec RR |
203 | MODULE_DEVICE_TABLE(virtio, id_table); |
204 | MODULE_DESCRIPTION("Virtio random number driver"); | |
205 | MODULE_LICENSE("GPL"); |