virtio: rng: Add a random number generator(rng) driver
Add a driver for the virtio-rng device on the qemu platform. The
device uses pci as a transport medium. The driver can be enabled with
the following configs
CONFIG_VIRTIO
CONFIG_DM_RNG
CONFIG_VIRTIO_PCI
CONFIG_VIRTIO_RNG
Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
diff --git a/drivers/virtio/virtio_rng.c b/drivers/virtio/virtio_rng.c
new file mode 100644
index 0000000..4edffa6
--- /dev/null
+++ b/drivers/virtio/virtio_rng.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2019, Linaro Limited
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <rng.h>
+#include <virtio_types.h>
+#include <virtio.h>
+#include <virtio_ring.h>
+
+#define BUFFER_SIZE 16UL
+
+struct virtio_rng_priv {
+ struct virtqueue *rng_vq;
+};
+
+static int virtio_rng_read(struct udevice *dev, void *data, size_t len)
+{
+ int ret;
+ unsigned int rsize;
+ unsigned char buf[BUFFER_SIZE] __aligned(4);
+ unsigned char *ptr = data;
+ struct virtio_sg sg;
+ struct virtio_sg *sgs[1];
+ struct virtio_rng_priv *priv = dev_get_priv(dev);
+
+ while (len) {
+ sg.addr = buf;
+ sg.length = min(len, sizeof(buf));
+ sgs[0] = &sg;
+
+ ret = virtqueue_add(priv->rng_vq, sgs, 0, 1);
+ if (ret)
+ return ret;
+
+ virtqueue_kick(priv->rng_vq);
+
+ while (!virtqueue_get_buf(priv->rng_vq, &rsize))
+ ;
+
+ memcpy(ptr, buf, rsize);
+ len -= rsize;
+ ptr += rsize;
+ }
+
+ return 0;
+}
+
+static int virtio_rng_bind(struct udevice *dev)
+{
+ struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(dev->parent);
+
+ /* Indicate what driver features we support */
+ virtio_driver_features_init(uc_priv, NULL, 0, NULL, 0);
+
+ return 0;
+}
+
+static int virtio_rng_probe(struct udevice *dev)
+{
+ struct virtio_rng_priv *priv = dev_get_priv(dev);
+ int ret;
+
+ ret = virtio_find_vqs(dev, 1, &priv->rng_vq);
+ if (ret < 0) {
+ debug("%s: virtio_find_vqs failed\n", __func__);
+ return ret;
+ }
+
+ return 0;
+}
+
+static const struct dm_rng_ops virtio_rng_ops = {
+ .read = virtio_rng_read,
+};
+
+U_BOOT_DRIVER(virtio_rng) = {
+ .name = VIRTIO_RNG_DRV_NAME,
+ .id = UCLASS_RNG,
+ .bind = virtio_rng_bind,
+ .probe = virtio_rng_probe,
+ .remove = virtio_reset,
+ .ops = &virtio_rng_ops,
+ .priv_auto_alloc_size = sizeof(struct virtio_rng_priv),
+ .flags = DM_FLAG_ACTIVE_DMA,
+};