On 12/27/19 3:23 PM, Sughosh Ganu wrote:
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 <[email protected]>
---
* Handle review comments from Heinrich Schuchardt to read all the
bytes requested in the individual drivers.
drivers/virtio/Kconfig | 6 +++
drivers/virtio/Makefile | 1 +
drivers/virtio/virtio-uclass.c | 1 +
drivers/virtio/virtio_rng.c | 87 ++++++++++++++++++++++++++++++++++++++++++
include/virtio.h | 4 +-
5 files changed, 98 insertions(+), 1 deletion(-)
create mode 100644 drivers/virtio/virtio_rng.c
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index a9d5fd0..2e3dd3b 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -59,4 +59,10 @@ config VIRTIO_BLK
This is the virtual block driver for virtio. It can be used with
QEMU based targets.
+config VIRTIO_RNG
+ bool "virtio rng driver"
+ depends on VIRTIO
+ help
+ This is the virtual random number generator driver. It can be used
+ with Qemu based targets.
endmenu
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
index 4579044..dc88809 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_VIRTIO_PCI) += virtio_pci_legacy.o
virtio_pci_modern.o
obj-$(CONFIG_VIRTIO_SANDBOX) += virtio_sandbox.o
obj-$(CONFIG_VIRTIO_NET) += virtio_net.o
obj-$(CONFIG_VIRTIO_BLK) += virtio_blk.o
+obj-$(CONFIG_VIRTIO_RNG) += virtio_rng.o
diff --git a/drivers/virtio/virtio-uclass.c b/drivers/virtio/virtio-uclass.c
index 34397d7..436faa4 100644
--- a/drivers/virtio/virtio-uclass.c
+++ b/drivers/virtio/virtio-uclass.c
@@ -24,6 +24,7 @@
static const char *const virtio_drv_name[VIRTIO_ID_MAX_NUM] = {
[VIRTIO_ID_NET] = VIRTIO_NET_DRV_NAME,
[VIRTIO_ID_BLOCK] = VIRTIO_BLK_DRV_NAME,
+ [VIRTIO_ID_RNG] = VIRTIO_RNG_DRV_NAME,
};
int virtio_get_config(struct udevice *vdev, unsigned int offset,
diff --git a/drivers/virtio/virtio_rng.c b/drivers/virtio/virtio_rng.c
new file mode 100644
index 0000000..f8c10bf
--- /dev/null
+++ b/drivers/virtio/virtio_rng.c
@@ -0,0 +1,87 @@
+// 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>
+
+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 = 0;
+ size_t nbytes = len;
+ unsigned char *buf = data;
+ struct virtio_sg sg;
+ struct virtio_sg *sgs[1];
+ struct virtio_rng_priv *priv = dev_get_priv(dev);
+
+ if (!len)
+ return 0;
+
+ do {
+ sg.addr = buf;
As described in the response to an earlier version of the patch the
address passed as sg.addr has to be 4 byte aligned because
virtqueue_get_buf() internally copies u32.
With
qemu-system-aarch64 -M virt \
-device virtio-rng-pci,disable-legacy=on,max-bytes=15,period=1000
sg.addr will not even be 4 byte aligned if data is 4 byte aligned.
So if QEMU some day will correctly emulate alignment traps this function
may lead to a crash.
So I would prefer to use a local variable as buffer and then copy the
random bytes from the buffer to data. See suggestion below.
Best regards
Heinrich
#define BUFFER_SIZE 16UL
static int virtio_rng_read(struct udevice *dev, void *data, size_t len)
{
int ret;
unsigned int rsize = 0;
unsigned char buf[BUFFER_SIZE];
unsigned char *ptr = data;
struct virtio_sg sg;
struct virtio_sg *sgs = sg;
struct virtio_rng_priv *priv = dev_get_priv(dev);
while (len) {
sg.addr = buf;
sg.length = min(BUFFER_SIZE, len);
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;
}
+ sg.length = nbytes;
+ 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))
+ ;
+ nbytes -= rsize;
+ buf += rsize;
+ } while (nbytes != 0);
+
+ 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,
+};
diff --git a/include/virtio.h b/include/virtio.h
index 654fdf1..561dcc3 100644
--- a/include/virtio.h
+++ b/include/virtio.h
@@ -22,10 +22,12 @@
#define VIRTIO_ID_NET 1 /* virtio net */
#define VIRTIO_ID_BLOCK 2 /* virtio block */
-#define VIRTIO_ID_MAX_NUM 3
+#define VIRTIO_ID_RNG 4 /* virtio rng */
+#define VIRTIO_ID_MAX_NUM 5
#define VIRTIO_NET_DRV_NAME "virtio-net"
#define VIRTIO_BLK_DRV_NAME "virtio-blk"
+#define VIRTIO_RNG_DRV_NAME "virtio-rng"
/* Status byte for guest to report progress, and synchronize features */
