diff options
Diffstat (limited to 'kernel/drivers/char/hw_random/virtio-rng.c')
| -rw-r--r-- | kernel/drivers/char/hw_random/virtio-rng.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/kernel/drivers/char/hw_random/virtio-rng.c b/kernel/drivers/char/hw_random/virtio-rng.c new file mode 100644 index 000000000..3fa2f8a00 --- /dev/null +++ b/kernel/drivers/char/hw_random/virtio-rng.c @@ -0,0 +1,212 @@ +/* + * 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 DEFINE_IDA(rng_index_ida); + +struct virtrng_info { + struct hwrng hwrng; + struct virtqueue *vq; + struct completion have_data; + char name[25]; + unsigned int data_avail; + int index; + bool busy; + bool hwrng_register_done; + bool hwrng_removed; +}; + +static void random_recv_done(struct virtqueue *vq) +{ + struct virtrng_info *vi = vq->vdev->priv; + + /* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */ + if (!virtqueue_get_buf(vi->vq, &vi->data_avail)) + return; + + complete(&vi->have_data); +} + +/* The host will fill any buffer we give it with sweet, sweet randomness. */ +static void register_buffer(struct virtrng_info *vi, u8 *buf, size_t size) +{ + struct scatterlist sg; + + sg_init_one(&sg, buf, size); + + /* There should always be room for one buffer. */ + virtqueue_add_inbuf(vi->vq, &sg, 1, buf, GFP_KERNEL); + + virtqueue_kick(vi->vq); +} + +static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) +{ + int ret; + struct virtrng_info *vi = (struct virtrng_info *)rng->priv; + + if (vi->hwrng_removed) + return -ENODEV; + + if (!vi->busy) { + vi->busy = true; + init_completion(&vi->have_data); + register_buffer(vi, buf, size); + } + + if (!wait) + return 0; + + ret = wait_for_completion_killable(&vi->have_data); + if (ret < 0) + return ret; + + vi->busy = false; + + return vi->data_avail; +} + +static void virtio_cleanup(struct hwrng *rng) +{ + struct virtrng_info *vi = (struct virtrng_info *)rng->priv; + + if (vi->busy) + wait_for_completion(&vi->have_data); +} + +static int probe_common(struct virtio_device *vdev) +{ + int err, index; + struct virtrng_info *vi = NULL; + + vi = kzalloc(sizeof(struct virtrng_info), GFP_KERNEL); + if (!vi) + return -ENOMEM; + + vi->index = index = ida_simple_get(&rng_index_ida, 0, 0, GFP_KERNEL); + if (index < 0) { + err = index; + goto err_ida; + } + sprintf(vi->name, "virtio_rng.%d", index); + init_completion(&vi->have_data); + + vi->hwrng = (struct hwrng) { + .read = virtio_read, + .cleanup = virtio_cleanup, + .priv = (unsigned long)vi, + .name = vi->name, + .quality = 1000, + }; + vdev->priv = vi; + + /* We expect a single virtqueue. */ + vi->vq = virtio_find_single_vq(vdev, random_recv_done, "input"); + if (IS_ERR(vi->vq)) { + err = PTR_ERR(vi->vq); + goto err_find; + } + + return 0; + +err_find: + ida_simple_remove(&rng_index_ida, index); +err_ida: + kfree(vi); + return err; +} + +static void remove_common(struct virtio_device *vdev) +{ + struct virtrng_info *vi = vdev->priv; + + vi->hwrng_removed = true; + vi->data_avail = 0; + complete(&vi->have_data); + vdev->config->reset(vdev); + vi->busy = false; + if (vi->hwrng_register_done) + hwrng_unregister(&vi->hwrng); + vdev->config->del_vqs(vdev); + ida_simple_remove(&rng_index_ida, vi->index); + kfree(vi); +} + +static int virtrng_probe(struct virtio_device *vdev) +{ + return probe_common(vdev); +} + +static void virtrng_remove(struct virtio_device *vdev) +{ + remove_common(vdev); +} + +static void virtrng_scan(struct virtio_device *vdev) +{ + struct virtrng_info *vi = vdev->priv; + int err; + + err = hwrng_register(&vi->hwrng); + if (!err) + vi->hwrng_register_done = true; +} + +#ifdef CONFIG_PM_SLEEP +static int virtrng_freeze(struct virtio_device *vdev) +{ + remove_common(vdev); + return 0; +} + +static int virtrng_restore(struct virtio_device *vdev) +{ + return probe_common(vdev); +} +#endif + +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 = virtrng_remove, + .scan = virtrng_scan, +#ifdef CONFIG_PM_SLEEP + .freeze = virtrng_freeze, + .restore = virtrng_restore, +#endif +}; + +module_virtio_driver(virtio_rng_driver); +MODULE_DEVICE_TABLE(virtio, id_table); +MODULE_DESCRIPTION("Virtio random number driver"); +MODULE_LICENSE("GPL"); |