Initial import

1 files changed, 212 insertions, 0 deletions

diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
new file mode 100644
index 000000000..3fa2f8a00
--- /dev/null
+++ b/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");