141 lines
3.2 KiB
C
141 lines
3.2 KiB
C
/*
|
|
* Randomness driver for virtio
|
|
* Copyright (C) 2007, 2008 Rusty Russell IBM Corporation
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
#include <linux/err.h>
|
|
#include <linux/hw_random.h>
|
|
#include <linux/scatterlist.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/virtio.h>
|
|
#include <linux/virtio_rng.h>
|
|
#include <linux/module.h>
|
|
|
|
static struct virtqueue *vq;
|
|
static unsigned int data_avail;
|
|
static DECLARE_COMPLETION(have_data);
|
|
static bool busy;
|
|
|
|
static void random_recv_done(struct virtqueue *vq)
|
|
{
|
|
/* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */
|
|
if (!virtqueue_get_buf(vq, &data_avail))
|
|
return;
|
|
|
|
complete(&have_data);
|
|
}
|
|
|
|
/* The host will fill any buffer we give it with sweet, sweet randomness. */
|
|
static void register_buffer(u8 *buf, size_t size)
|
|
{
|
|
struct scatterlist sg;
|
|
|
|
sg_init_one(&sg, buf, size);
|
|
|
|
/* There should always be room for one buffer. */
|
|
if (virtqueue_add_buf(vq, &sg, 0, 1, buf, GFP_KERNEL) < 0)
|
|
BUG();
|
|
|
|
virtqueue_kick(vq);
|
|
}
|
|
|
|
static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait)
|
|
{
|
|
|
|
if (!busy) {
|
|
busy = true;
|
|
init_completion(&have_data);
|
|
register_buffer(buf, size);
|
|
}
|
|
|
|
if (!wait)
|
|
return 0;
|
|
|
|
wait_for_completion(&have_data);
|
|
|
|
busy = false;
|
|
|
|
return data_avail;
|
|
}
|
|
|
|
static void virtio_cleanup(struct hwrng *rng)
|
|
{
|
|
if (busy)
|
|
wait_for_completion(&have_data);
|
|
}
|
|
|
|
|
|
static struct hwrng virtio_hwrng = {
|
|
.name = "virtio",
|
|
.cleanup = virtio_cleanup,
|
|
.read = virtio_read,
|
|
};
|
|
|
|
static int virtrng_probe(struct virtio_device *vdev)
|
|
{
|
|
int err;
|
|
|
|
/* We expect a single virtqueue. */
|
|
vq = virtio_find_single_vq(vdev, random_recv_done, "input");
|
|
if (IS_ERR(vq))
|
|
return PTR_ERR(vq);
|
|
|
|
err = hwrng_register(&virtio_hwrng);
|
|
if (err) {
|
|
vdev->config->del_vqs(vdev);
|
|
return err;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __devexit virtrng_remove(struct virtio_device *vdev)
|
|
{
|
|
vdev->config->reset(vdev);
|
|
hwrng_unregister(&virtio_hwrng);
|
|
vdev->config->del_vqs(vdev);
|
|
}
|
|
|
|
static struct virtio_device_id id_table[] = {
|
|
{ VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID },
|
|
{ 0 },
|
|
};
|
|
|
|
static struct virtio_driver virtio_rng_driver = {
|
|
.driver.name = KBUILD_MODNAME,
|
|
.driver.owner = THIS_MODULE,
|
|
.id_table = id_table,
|
|
.probe = virtrng_probe,
|
|
.remove = __devexit_p(virtrng_remove),
|
|
};
|
|
|
|
static int __init init(void)
|
|
{
|
|
return register_virtio_driver(&virtio_rng_driver);
|
|
}
|
|
|
|
static void __exit fini(void)
|
|
{
|
|
unregister_virtio_driver(&virtio_rng_driver);
|
|
}
|
|
module_init(init);
|
|
module_exit(fini);
|
|
|
|
MODULE_DEVICE_TABLE(virtio, id_table);
|
|
MODULE_DESCRIPTION("Virtio random number driver");
|
|
MODULE_LICENSE("GPL");
|