On 12/24/19 10:39 PM, Heinrich Schuchardt wrote:
On 12/17/19 12:52 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 sughosh.ganu@linaro.org
drivers/virtio/Kconfig | 6 ++++ drivers/virtio/Makefile | 1 + drivers/virtio/virtio-uclass.c | 1 + drivers/virtio/virtio_rng.c | 72 ++++++++++++++++++++++++++++++++++++++++++ include/virtio.h | 4 ++- 5 files changed, 83 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..19a0cc1 --- /dev/null +++ b/drivers/virtio/virtio_rng.c @@ -0,0 +1,72 @@ +// 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) +{ + struct virtio_sg sg = { data, len }; + struct virtio_sg *sgs[] = { &sg }; + struct virtio_rng_priv *priv = dev_get_priv(dev); + unsigned int rsize; + int ret;
+ ret = virtqueue_add(priv->rng_vq, sgs, 0, 1); + if (ret)
Please, add a debug statement for each error path, e.g.
debug("%s: virtqueue_add() failed\n", __func__)
+ return ret;
+ virtqueue_kick(priv->rng_vq);
+ while (!virtqueue_get_buf(priv->rng_vq, &rsize)) + ;
+ return rsize;
The return value is inconsistent with sandbox_rng_read() and stm32_rng_read(). Both return 0 on success.
With "return 0;" the driver works fine.
I retested with -device virtio-rng-pci,disable-legacy=on,max-bytes=16,period=1000
In this case virtqueue_get_buf() only returns a maximum of 16 bytes. All other bytes of data remain unchanged. If the next call occurs within 1000 milli-seconds virtqueue_get_buf() blocks until the period is over.
So either you have to change the definition of the return parameter in patch 1/8 (and change the other drivers accordingly) or you have to add a loop to this driver that loops until len random bytes have been retrieved.
I would prefer to add a loop in the driver instead of adding a loop in every consumer.
Best regards
Heinrich
+}
+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)
Add a debug statement here, please, e.g.
debug("%s: virtio_find_vqs() failed\n", __func__)
Best regards
Heinrich
+ 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 */