With this driver enabled, -device virtio-rng-device can now be passed to Qemu for barebox to detect a VirtIO RNG device. If barebox is passed as argument to the Qemu -kernel option, no device tree changes are necessary.
Signed-off-by: Ahmad Fatoum <[email protected]> --- drivers/hw_random/Kconfig | 7 ++ drivers/hw_random/Makefile | 1 + drivers/hw_random/virtio-rng.c | 120 +++++++++++++++++++++++++++++++++ 3 files changed, 128 insertions(+) create mode 100644 drivers/hw_random/virtio-rng.c diff --git a/drivers/hw_random/Kconfig b/drivers/hw_random/Kconfig index 1923c755dbba..a84c03efef90 100644 --- a/drivers/hw_random/Kconfig +++ b/drivers/hw_random/Kconfig @@ -29,4 +29,11 @@ config HWRNG_DEV_RANDOM This driver allows use of the host provided /dev/urandom as barebox HWRNGs. +config HW_RANDOM_VIRTIO + tristate "VirtIO Random Number Generator support" + depends on VIRTIO + help + This driver provides guest-side support for the virtual Random Number + Generator hardware. + endif diff --git a/drivers/hw_random/Makefile b/drivers/hw_random/Makefile index 2e318be738c5..4bab3967fc4d 100644 --- a/drivers/hw_random/Makefile +++ b/drivers/hw_random/Makefile @@ -2,3 +2,4 @@ obj-$(CONFIG_HWRNG) += core.o obj-$(CONFIG_HWRNG_MXC_RNGC) += mxc-rngc.o obj-$(CONFIG_HWRNG_STM32) += stm32-rng.o obj-$(CONFIG_HWRNG_DEV_RANDOM) += dev-random.o +obj-$(CONFIG_HW_RANDOM_VIRTIO) += virtio-rng.o diff --git a/drivers/hw_random/virtio-rng.c b/drivers/hw_random/virtio-rng.c new file mode 100644 index 000000000000..fbf1a5715a33 --- /dev/null +++ b/drivers/hw_random/virtio-rng.c @@ -0,0 +1,120 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Randomness driver for virtio + * Copyright (C) 2007, 2008 Rusty Russell IBM Corporation + */ + +#include <common.h> +#include <linux/err.h> +#include <linux/hw_random.h> +#include <linux/spinlock.h> +#include <linux/virtio.h> +#include <linux/virtio_rng.h> +#include <linux/virtio_ring.h> +#include <module.h> +#include <linux/slab.h> + +#define BUFFER_SIZE 16UL + +struct virtrng_info { + struct hwrng hwrng; + char name[25]; + struct virtqueue *rng_vq; + bool hwrng_register_done; +}; + +static inline struct virtrng_info *to_virtrng_info(struct hwrng *hwrng) +{ + return container_of(hwrng, struct virtrng_info, hwrng); +} + +static int virtio_rng_read(struct hwrng *hwrng, void *data, size_t len, bool wait) +{ + 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 virtrng_info *vi = to_virtrng_info(hwrng); + size_t remaining = len; + + while (remaining) { + sg.addr = buf; + sg.length = min(remaining, sizeof(buf)); + sgs[0] = &sg; + + ret = virtqueue_add(vi->rng_vq, sgs, 0, 1); + if (ret) + return ret; + + virtqueue_kick(vi->rng_vq); + + while (!virtqueue_get_buf(vi->rng_vq, &rsize)) + ; + + memcpy(ptr, buf, rsize); + remaining -= rsize; + ptr += rsize; + } + + return len; +} + +static int probe_common(struct virtio_device *vdev) +{ + struct virtrng_info *vi; + + vi = xzalloc(sizeof(*vi)); + + vi->hwrng.name = vdev->dev.name; + vi->hwrng.read = virtio_rng_read; + + vdev->priv = vi; + + /* We expect a single virtqueue. */ + return virtio_find_vqs(vdev, 1, &vi->rng_vq); +} + +static void remove_common(struct virtio_device *vdev) +{ + vdev->config->reset(vdev); + vdev->config->del_vqs(vdev); +} + +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(&vdev->dev, &vi->hwrng); + if (!err) + vi->hwrng_register_done = true; +} + +static const struct virtio_device_id id_table[] = { + { VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID }, + { 0 }, +}; + +static struct virtio_driver virtio_rng_driver = { + .driver.name = "virtio-rng", + .id_table = id_table, + .probe = virtrng_probe, + .remove = virtrng_remove, + .scan = virtrng_scan, +}; + +module_virtio_driver(virtio_rng_driver); +MODULE_DESCRIPTION("Virtio random number driver"); +MODULE_LICENSE("GPL"); -- 2.30.0 _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox
