Commit | Line | Data |
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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 { | |
31 | struct virtio_device *vdev; | |
32 | struct hwrng hwrng; | |
33 | struct virtqueue *vq; | |
34 | unsigned int data_avail; | |
35 | struct completion have_data; | |
36 | bool busy; | |
a17597d3 SL |
37 | char name[25]; |
38 | int index; | |
08e53fbd | 39 | }; |
f7f510ec | 40 | |
e052dbf5 AS |
41 | static bool probe_done; |
42 | ||
f7f510ec RR |
43 | static void random_recv_done(struct virtqueue *vq) |
44 | { | |
08e53fbd AK |
45 | struct virtrng_info *vi = vq->vdev->priv; |
46 | ||
e5b89542 | 47 | /* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */ |
08e53fbd | 48 | if (!virtqueue_get_buf(vi->vq, &vi->data_avail)) |
e5b89542 | 49 | return; |
f7f510ec | 50 | |
08e53fbd | 51 | complete(&vi->have_data); |
f7f510ec RR |
52 | } |
53 | ||
bb347d98 | 54 | /* The host will fill any buffer we give it with sweet, sweet randomness. */ |
08e53fbd | 55 | static void register_buffer(struct virtrng_info *vi, u8 *buf, size_t size) |
f7f510ec RR |
56 | { |
57 | struct scatterlist sg; | |
58 | ||
bb347d98 IM |
59 | sg_init_one(&sg, buf, size); |
60 | ||
f7f510ec | 61 | /* There should always be room for one buffer. */ |
08e53fbd | 62 | virtqueue_add_inbuf(vi->vq, &sg, 1, buf, GFP_KERNEL); |
bb347d98 | 63 | |
08e53fbd | 64 | virtqueue_kick(vi->vq); |
f7f510ec RR |
65 | } |
66 | ||
bb347d98 | 67 | static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) |
f7f510ec | 68 | { |
cc8744e1 | 69 | int ret; |
08e53fbd | 70 | struct virtrng_info *vi = (struct virtrng_info *)rng->priv; |
f7f510ec | 71 | |
e052dbf5 AS |
72 | /* |
73 | * Don't ask host for data till we're setup. This call can | |
74 | * happen during hwrng_register(), after commit d9e7972619. | |
75 | */ | |
76 | if (unlikely(!probe_done)) | |
77 | return 0; | |
78 | ||
08e53fbd AK |
79 | if (!vi->busy) { |
80 | vi->busy = true; | |
81 | init_completion(&vi->have_data); | |
82 | register_buffer(vi, buf, size); | |
bb347d98 IM |
83 | } |
84 | ||
f7f510ec RR |
85 | if (!wait) |
86 | return 0; | |
87 | ||
08e53fbd | 88 | ret = wait_for_completion_killable(&vi->have_data); |
cc8744e1 AS |
89 | if (ret < 0) |
90 | return ret; | |
594de1dd | 91 | |
08e53fbd | 92 | vi->busy = false; |
594de1dd | 93 | |
08e53fbd | 94 | return vi->data_avail; |
f7f510ec RR |
95 | } |
96 | ||
bb347d98 | 97 | static void virtio_cleanup(struct hwrng *rng) |
f7f510ec | 98 | { |
08e53fbd | 99 | struct virtrng_info *vi = (struct virtrng_info *)rng->priv; |
bb347d98 | 100 | |
08e53fbd AK |
101 | if (vi->busy) |
102 | wait_for_completion(&vi->have_data); | |
103 | } | |
f7f510ec | 104 | |
178d855e | 105 | static int probe_common(struct virtio_device *vdev) |
f7f510ec | 106 | { |
a17597d3 | 107 | int err, index; |
08e53fbd AK |
108 | struct virtrng_info *vi = NULL; |
109 | ||
e5d23a8c | 110 | vi = kzalloc(sizeof(struct virtrng_info), GFP_KERNEL); |
a17597d3 SL |
111 | if (!vi) |
112 | return -ENOMEM; | |
113 | ||
114 | vi->index = index = ida_simple_get(&rng_index_ida, 0, 0, GFP_KERNEL); | |
115 | if (index < 0) { | |
116 | kfree(vi); | |
117 | return index; | |
118 | } | |
119 | sprintf(vi->name, "virtio_rng.%d", index); | |
08e53fbd AK |
120 | init_completion(&vi->have_data); |
121 | ||
a17597d3 SL |
122 | vi->hwrng = (struct hwrng) { |
123 | .read = virtio_read, | |
124 | .cleanup = virtio_cleanup, | |
125 | .priv = (unsigned long)vi, | |
126 | .name = vi->name, | |
127 | }; | |
08e53fbd | 128 | vdev->priv = vi; |
f7f510ec RR |
129 | |
130 | /* We expect a single virtqueue. */ | |
08e53fbd AK |
131 | vi->vq = virtio_find_single_vq(vdev, random_recv_done, "input"); |
132 | if (IS_ERR(vi->vq)) { | |
133 | err = PTR_ERR(vi->vq); | |
08e53fbd AK |
134 | vi->vq = NULL; |
135 | kfree(vi); | |
a17597d3 | 136 | ida_simple_remove(&rng_index_ida, index); |
e84e7a56 AS |
137 | return err; |
138 | } | |
f7f510ec | 139 | |
a17597d3 | 140 | err = hwrng_register(&vi->hwrng); |
f7f510ec | 141 | if (err) { |
d2a7ddda | 142 | vdev->config->del_vqs(vdev); |
08e53fbd AK |
143 | vi->vq = NULL; |
144 | kfree(vi); | |
a17597d3 | 145 | ida_simple_remove(&rng_index_ida, index); |
f7f510ec RR |
146 | return err; |
147 | } | |
148 | ||
e052dbf5 | 149 | probe_done = true; |
f7f510ec RR |
150 | return 0; |
151 | } | |
152 | ||
178d855e | 153 | static void remove_common(struct virtio_device *vdev) |
f7f510ec | 154 | { |
08e53fbd | 155 | struct virtrng_info *vi = vdev->priv; |
f7f510ec | 156 | vdev->config->reset(vdev); |
08e53fbd AK |
157 | vi->busy = false; |
158 | hwrng_unregister(&vi->hwrng); | |
d2a7ddda | 159 | vdev->config->del_vqs(vdev); |
a17597d3 | 160 | ida_simple_remove(&rng_index_ida, vi->index); |
08e53fbd | 161 | kfree(vi); |
f7f510ec RR |
162 | } |
163 | ||
178d855e AS |
164 | static int virtrng_probe(struct virtio_device *vdev) |
165 | { | |
166 | return probe_common(vdev); | |
167 | } | |
168 | ||
39af33fc | 169 | static void virtrng_remove(struct virtio_device *vdev) |
178d855e AS |
170 | { |
171 | remove_common(vdev); | |
172 | } | |
173 | ||
89107000 | 174 | #ifdef CONFIG_PM_SLEEP |
0bc1a2ef AS |
175 | static int virtrng_freeze(struct virtio_device *vdev) |
176 | { | |
177 | remove_common(vdev); | |
178 | return 0; | |
179 | } | |
180 | ||
181 | static int virtrng_restore(struct virtio_device *vdev) | |
182 | { | |
183 | return probe_common(vdev); | |
184 | } | |
185 | #endif | |
186 | ||
f7f510ec RR |
187 | static struct virtio_device_id id_table[] = { |
188 | { VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID }, | |
189 | { 0 }, | |
190 | }; | |
191 | ||
d817cd52 | 192 | static struct virtio_driver virtio_rng_driver = { |
f7f510ec RR |
193 | .driver.name = KBUILD_MODNAME, |
194 | .driver.owner = THIS_MODULE, | |
195 | .id_table = id_table, | |
196 | .probe = virtrng_probe, | |
bcd2982a | 197 | .remove = virtrng_remove, |
89107000 | 198 | #ifdef CONFIG_PM_SLEEP |
0bc1a2ef AS |
199 | .freeze = virtrng_freeze, |
200 | .restore = virtrng_restore, | |
201 | #endif | |
f7f510ec RR |
202 | }; |
203 | ||
b2a17029 | 204 | module_virtio_driver(virtio_rng_driver); |
f7f510ec RR |
205 | MODULE_DEVICE_TABLE(virtio, id_table); |
206 | MODULE_DESCRIPTION("Virtio random number driver"); | |
207 | MODULE_LICENSE("GPL"); |