[PATCH 1/1] virtio: add driver for virtio_console devices
Ahmad Fatoum
a.fatoum at pengutronix.de
Tue Jun 13 17:22:17 CEST 2023
Hello,
On 06.06.23 15:25, Ying-Chun Liu (PaulLiu) wrote:
> From: "A. Cody Schuffelen" <schuffelen at google.com>
>
> This is an implementation of single-character virtio-console. Part of the
> patch is based on barebox implementations.
Cool to see others found this useful. I had originally written this for the demo
at https://barebox.org/jsbarebox/ :-)
Back then I had trouble getting more than one console to work, whether through
multiport consoles or via having one virtio device per console. The original
barebox source code has a comment about what I tried. Did you manage to resolve
this limitation?
If not, you should add some check into your patch to prevent registering more than
one console with the driver.
Cheers,
Ahmad
>
> Signed-off-by: A. Cody Schuffelen <schuffelen at google.com>
> [ Paul: pick from the Android tree. Rebase to the upstream. Small fixes. ]
> Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu at linaro.org>
> Link: https://android.googlesource.com/platform/external/u-boot/+/bc68da98ebf835a50d869cf01c535ac936bfcb11
> Link: https://git.pengutronix.de/cgit/barebox/tree/drivers/serial/virtio_console.c?id=180a551d542844b70012d7b94a415aacdcf31d45
> Link: https://android.googlesource.com/platform/external/u-boot/+/4581f7c6e96d7332b534ae20de356a4554594d08
> Cc: Bin Meng <bmeng.cn at gmail.com>
> ---
> drivers/virtio/Kconfig | 8 ++
> drivers/virtio/Makefile | 1 +
> drivers/virtio/virtio-uclass.c | 1 +
> drivers/virtio/virtio_console.c | 158 ++++++++++++++++++++++++++++++++
> include/virtio.h | 2 +
> 5 files changed, 170 insertions(+)
> create mode 100644 drivers/virtio/virtio_console.c
>
> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
> index 852f6735b6..94aaf70ab9 100644
> --- a/drivers/virtio/Kconfig
> +++ b/drivers/virtio/Kconfig
> @@ -68,6 +68,14 @@ config VIRTIO_BLK
> This is the virtual block driver for virtio. It can be used with
> QEMU based targets.
>
> +config VIRTIO_CONSOLE
> + bool "virtio console driver"
> + depends on VIRTIO
> + default y
> + help
> + This is the virtual console driver for virtio. It can be used
> + with QEMU based targets.
> +
> config VIRTIO_RNG
> bool "virtio rng driver"
> depends on DM_RNG
> diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
> index 4c63a6c690..c816f66aa6 100644
> --- a/drivers/virtio/Makefile
> +++ b/drivers/virtio/Makefile
> @@ -10,4 +10,5 @@ obj-$(CONFIG_VIRTIO_PCI_LEGACY) += virtio_pci_legacy.o
> obj-$(CONFIG_VIRTIO_SANDBOX) += virtio_sandbox.o
> obj-$(CONFIG_VIRTIO_NET) += virtio_net.o
> obj-$(CONFIG_VIRTIO_BLK) += virtio_blk.o
> +obj-$(CONFIG_VIRTIO_CONSOLE) += virtio_console.o
> obj-$(CONFIG_VIRTIO_RNG) += virtio_rng.o
> diff --git a/drivers/virtio/virtio-uclass.c b/drivers/virtio/virtio-uclass.c
> index 31bb21c534..9c54c67572 100644
> --- a/drivers/virtio/virtio-uclass.c
> +++ b/drivers/virtio/virtio-uclass.c
> @@ -30,6 +30,7 @@
> 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_CONSOLE] = VIRTIO_CONSOLE_DRV_NAME,
> [VIRTIO_ID_RNG] = VIRTIO_RNG_DRV_NAME,
> };
>
> diff --git a/drivers/virtio/virtio_console.c b/drivers/virtio/virtio_console.c
> new file mode 100644
> index 0000000000..1d4b319b08
> --- /dev/null
> +++ b/drivers/virtio/virtio_console.c
> @@ -0,0 +1,158 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen at iki.fi>
> + * Copyright (C) 2018, Bin Meng <bmeng.cn at gmail.com>
> + * Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation
> + * Copyright (C) 2009, 2010, 2011 Red Hat, Inc.
> + * Copyright (C) 2009, 2010, 2011 Amit Shah <amit.shah at redhat.com>
> + * Copyright (C) 2021 Ahmad Fatoum
> + * Copyright (C) 2021, Google LLC, schuffelen at google.com (A. Cody Schuffelen)
> + * Copyright (C) 2023, Linaro
> + */
> +
> +#include <common.h>
> +#include <blk.h>
> +#include <dm.h>
> +#include <part.h>
> +#include <serial.h>
> +#include <virtio_types.h>
> +#include <virtio.h>
> +#include <virtio_ring.h>
> +#include "virtio_blk.h"
> +
> +struct virtio_console_priv {
> + struct virtqueue *receiveq_port0;
> + struct virtqueue *transmitq_port0;
> + unsigned char inbuf[1] __aligned(4);
> +};
> +
> +static int virtio_console_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;
> +}
> +
> +/*
> + * Create a scatter-gather list representing our input buffer and put
> + * it in the queue.
> + */
> +static void add_inbuf(struct virtio_console_priv *priv)
> +{
> + struct virtio_sg sg;
> + struct virtio_sg *sgs[1];
> + int ret;
> +
> + sgs[0] = &sg;
> + sg.addr = priv->inbuf;
> + sg.length = sizeof(priv->inbuf);
> +
> + ret = virtqueue_add(priv->receiveq_port0, sgs, 0, 1);
> + /* We should always be able to add one buffer to an empty queue. */
> + WARN(ret < 0, "%s: virtqueue_add failed\n", __func__);
> +
> + virtqueue_kick(priv->receiveq_port0);
> +}
> +
> +static int virtio_console_probe(struct udevice *dev)
> +{
> + struct virtio_console_priv *priv = dev_get_priv(dev);
> + int ret;
> +
> + struct virtqueue *virtqueues[2];
> +
> + ret = virtio_find_vqs(dev, 2, virtqueues);
> + if (ret < 0) {
> + debug("%s: virtio_find_vqs failed\n", __func__);
> + return ret;
> + }
> +
> + priv->receiveq_port0 = virtqueues[0];
> + priv->transmitq_port0 = virtqueues[1];
> +
> + /* Register the input buffer the first time. */
> + add_inbuf(priv);
> +
> + return 0;
> +}
> +
> +static int virtio_console_serial_setbrg(struct udevice *dev, int baudrate)
> +{
> + return 0;
> +}
> +
> +static int virtio_console_serial_pending(struct udevice *dev, bool input)
> +{
> + struct virtio_console_priv *priv = dev_get_priv(dev);
> +
> + return virtqueue_poll(priv->receiveq_port0,
> + priv->receiveq_port0->last_used_idx);
> +}
> +
> +static int virtio_console_serial_getc(struct udevice *dev)
> +{
> + struct virtio_console_priv *priv = dev_get_priv(dev);
> + unsigned char *in;
> + int ch;
> + unsigned int len = 0;
> +
> + in = virtqueue_get_buf(priv->receiveq_port0, &len);
> + if (!in)
> + return -EAGAIN;
> +
> + WARN(len != 1, "%s: too much data: %d\n", __func__, len);
> +
> + ch = *in;
> +
> + add_inbuf(priv);
> +
> + return ch;
> +}
> +
> +static int virtio_console_serial_putc(struct udevice *dev, const char ch)
> +{
> + struct virtio_console_priv *priv = dev_get_priv(dev);
> + struct virtio_sg sg;
> + struct virtio_sg *sgs[1];
> + unsigned char buf[1] __aligned(4);
> + int ret = 0;
> +
> + sg.addr = buf;
> + sg.length = sizeof(buf);
> + sgs[0] = &sg;
> + buf[0] = ch;
> +
> + ret = virtqueue_add(priv->transmitq_port0, sgs, 1, 0);
> + if (ret) {
> + debug("%s: virtqueue_add failed\n", __func__);
> + return ret;
> + }
> +
> + virtqueue_kick(priv->transmitq_port0);
> +
> + while (!virtqueue_get_buf(priv->transmitq_port0, NULL))
> + ;
> +
> + return 0;
> +}
> +
> +static const struct dm_serial_ops virtio_console_serial_ops = {
> + .putc = virtio_console_serial_putc,
> + .pending = virtio_console_serial_pending,
> + .getc = virtio_console_serial_getc,
> + .setbrg = virtio_console_serial_setbrg,
> +};
> +
> +U_BOOT_DRIVER(virtio_console) = {
> + .name = VIRTIO_CONSOLE_DRV_NAME,
> + .id = UCLASS_SERIAL,
> + .ops = &virtio_console_serial_ops,
> + .bind = virtio_console_bind,
> + .probe = virtio_console_probe,
> + .remove = virtio_reset,
> + .priv_auto = sizeof(struct virtio_console_priv),
> + .flags = DM_FLAG_ACTIVE_DMA,
> +};
> diff --git a/include/virtio.h b/include/virtio.h
> index 062a24630c..e36dd41fd1 100644
> --- a/include/virtio.h
> +++ b/include/virtio.h
> @@ -25,11 +25,13 @@
> #include <linux/bug.h>
> #define VIRTIO_ID_NET 1 /* virtio net */
> #define VIRTIO_ID_BLOCK 2 /* virtio block */
> +#define VIRTIO_ID_CONSOLE 3 /* virtio console */
> #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_CONSOLE_DRV_NAME "virtio-console"
> #define VIRTIO_RNG_DRV_NAME "virtio-rng"
>
> /* Status byte for guest to report progress, and synchronize features */
--
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