2 * Randomness driver for virtio
3 * Copyright (C) 2007, 2008 Rusty Russell IBM Corporation
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.
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.
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
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>
28 static DEFINE_IDA(rng_index_ida);
33 struct completion have_data;
35 unsigned int data_avail;
38 bool hwrng_register_done;
43 static void random_recv_done(struct virtqueue *vq)
45 struct virtrng_info *vi = vq->vdev->priv;
47 /* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */
48 if (!virtqueue_get_buf(vi->vq, &vi->data_avail))
51 complete(&vi->have_data);
54 /* The host will fill any buffer we give it with sweet, sweet randomness. */
55 static void register_buffer(struct virtrng_info *vi, u8 *buf, size_t size)
57 struct scatterlist sg;
59 sg_init_one(&sg, buf, size);
61 /* There should always be room for one buffer. */
62 virtqueue_add_inbuf(vi->vq, &sg, 1, buf, GFP_KERNEL);
64 virtqueue_kick(vi->vq);
67 static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait)
70 struct virtrng_info *vi = (struct virtrng_info *)rng->priv;
72 if (vi->hwrng_removed)
77 init_completion(&vi->have_data);
78 register_buffer(vi, buf, size);
84 ret = wait_for_completion_killable(&vi->have_data);
90 return vi->data_avail;
93 static void virtio_cleanup(struct hwrng *rng)
95 struct virtrng_info *vi = (struct virtrng_info *)rng->priv;
98 wait_for_completion(&vi->have_data);
101 static int probe_common(struct virtio_device *vdev)
104 struct virtrng_info *vi = NULL;
106 vi = kzalloc(sizeof(struct virtrng_info), GFP_KERNEL);
110 vi->index = index = ida_simple_get(&rng_index_ida, 0, 0, GFP_KERNEL);
115 sprintf(vi->name, "virtio_rng.%d", index);
116 init_completion(&vi->have_data);
118 vi->hwrng = (struct hwrng) {
120 .cleanup = virtio_cleanup,
121 .priv = (unsigned long)vi,
127 /* We expect a single virtqueue. */
128 vi->vq = virtio_find_single_vq(vdev, random_recv_done, "input");
129 if (IS_ERR(vi->vq)) {
130 err = PTR_ERR(vi->vq);
133 ida_simple_remove(&rng_index_ida, index);
140 static void remove_common(struct virtio_device *vdev)
142 struct virtrng_info *vi = vdev->priv;
144 vi->hwrng_removed = true;
146 complete(&vi->have_data);
147 vdev->config->reset(vdev);
149 if (vi->hwrng_register_done)
150 hwrng_unregister(&vi->hwrng);
151 vdev->config->del_vqs(vdev);
152 ida_simple_remove(&rng_index_ida, vi->index);
156 static int virtrng_probe(struct virtio_device *vdev)
158 return probe_common(vdev);
161 static void virtrng_remove(struct virtio_device *vdev)
166 static void virtrng_scan(struct virtio_device *vdev)
168 struct virtrng_info *vi = vdev->priv;
171 err = hwrng_register(&vi->hwrng);
173 vi->hwrng_register_done = true;
176 #ifdef CONFIG_PM_SLEEP
177 static int virtrng_freeze(struct virtio_device *vdev)
183 static int virtrng_restore(struct virtio_device *vdev)
185 return probe_common(vdev);
189 static struct virtio_device_id id_table[] = {
190 { VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID },
194 static struct virtio_driver virtio_rng_driver = {
195 .driver.name = KBUILD_MODNAME,
196 .driver.owner = THIS_MODULE,
197 .id_table = id_table,
198 .probe = virtrng_probe,
199 .remove = virtrng_remove,
200 .scan = virtrng_scan,
201 #ifdef CONFIG_PM_SLEEP
202 .freeze = virtrng_freeze,
203 .restore = virtrng_restore,
207 module_virtio_driver(virtio_rng_driver);
208 MODULE_DEVICE_TABLE(virtio, id_table);
209 MODULE_DESCRIPTION("Virtio random number driver");
210 MODULE_LICENSE("GPL");