From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from relay8-d.mail.gandi.net ([217.70.183.201]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1lE5IQ-0005L0-MF for barebox@lists.infradead.org; Mon, 22 Feb 2021 07:06:23 +0000 From: Ahmad Fatoum Date: Mon, 22 Feb 2021 08:06:01 +0100 Message-Id: <20210222070605.589180-6-ahmad@a3f.at> In-Reply-To: <20210222070605.589180-1-ahmad@a3f.at> References: <20210222070605.589180-1-ahmad@a3f.at> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: [PATCH 5/8] serial: add basic VirtIO console driver To: barebox@lists.infradead.org Cc: rcz@pengutronix.de With this driver enabled, -device virtio-serial-device can now be passed to Qemu for barebox to detect a VirtIO console device. If barebox is passed as argument to the Qemu -kernel option, no device tree changes are necessary. Example: $ qemu-system-arm -m 256M -M virt -nographic \ -kernel build/images/barebox-dt-2nd.img \ -device virtio-serial-device \ -chardev socket,path=/tmp/foo,server,nowait,id=foo \ -device virtconsole,chardev=foo,name=console.foo Signed-off-by: Ahmad Fatoum --- drivers/serial/Kconfig | 8 ++ drivers/serial/Makefile | 1 + drivers/serial/virtio_console.c | 166 ++++++++++++++++++++++++++++ include/uapi/linux/virtio_console.h | 78 +++++++++++++ 4 files changed, 253 insertions(+) create mode 100644 drivers/serial/virtio_console.c create mode 100644 include/uapi/linux/virtio_console.h diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig index 5c6f0e88e398..09434c1ba86c 100644 --- a/drivers/serial/Kconfig +++ b/drivers/serial/Kconfig @@ -156,4 +156,12 @@ config DRIVER_SERIAL_LPUART default y bool "LPUART serial driver" +config VIRTIO_CONSOLE + tristate "Virtio console" + select VIRTIO + help + Virtio console for use with hypervisors. + + Also serves as a general-purpose serial device for data + transfer between the guest and host. endmenu diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile index 8a2abbbe45cf..7ff41cd5c744 100644 --- a/drivers/serial/Makefile +++ b/drivers/serial/Makefile @@ -22,3 +22,4 @@ obj-$(CONFIG_DRIVER_SERIAL_CADENCE) += serial_cadence.o obj-$(CONFIG_DRIVER_SERIAL_EFI_STDIO) += efi-stdio.o obj-$(CONFIG_DRIVER_SERIAL_DIGIC) += serial_digic.o obj-$(CONFIG_DRIVER_SERIAL_LPUART) += serial_lpuart.o +obj-$(CONFIG_VIRTIO_CONSOLE) += virtio_console.o diff --git a/drivers/serial/virtio_console.c b/drivers/serial/virtio_console.c new file mode 100644 index 000000000000..a1331035d9ef --- /dev/null +++ b/drivers/serial/virtio_console.c @@ -0,0 +1,166 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation + * Copyright (C) 2009, 2010, 2011 Red Hat, Inc. + * Copyright (C) 2009, 2010, 2011 Amit Shah + * Copyright (C) 2021 Ahmad Fatoum + * + * This ridiculously simple implementation does a DMA transfer for + * every single character. On the plus side, we neither need to + * buffer RX or to wade through TX to turn LFs to CRLFs. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +struct virtio_console { + struct console_device cdev; + struct virtqueue *in_vq, *out_vq; + char inbuf[1]; +}; + +static bool have_one; + +/* + * The put_chars() callback is pretty straightforward. + * + * We turn the characters into a scatter-gather list, add it to the + * output queue and then kick the Host. Then we sit here waiting for + * it to finish: inefficient in theory, but in practice + * implementations will do it immediately (lguest's Launcher does). + */ +static void put_chars(struct virtio_console *virtcons, const char *buf, int count) +{ + struct virtqueue *out_vq = virtcons->out_vq; + unsigned int len; + struct virtio_sg *sgs[1] = { + &(struct virtio_sg) { .addr = (void *)buf, .length = count } + }; + + /* + * add_buf wants a token to identify this buffer: we hand it + * any non-NULL pointer, since there's only ever one buffer. + */ + if (virtqueue_add(out_vq, sgs, 1, 0) >= 0) { + /* Tell Host to go! */ + virtqueue_kick(out_vq); + /* Chill out until it's done with the buffer. */ + while (!virtqueue_get_buf(out_vq, &len)) + cpu_relax(); + } +} + +static void virtcons_putc(struct console_device *cdev, char c) +{ + struct virtio_console *virtcons = container_of(cdev, struct virtio_console, cdev); + + return put_chars(virtcons, &c, 1); +} + +/* + * Create a scatter-gather list representing our input buffer and put + * it in the queue. + */ +static void add_inbuf(struct virtio_console *virtcons) +{ + struct virtio_sg *sgs[1] = { &(struct virtio_sg) { + .addr = virtcons->inbuf, .length = sizeof(virtcons->inbuf) } + }; + + /* We should always be able to add one buffer to an empty queue. */ + if (virtqueue_add(virtcons->in_vq, sgs, 0, 1) < 0) + BUG(); + virtqueue_kick(virtcons->in_vq); +} + +static int virtcons_tstc(struct console_device *cdev) +{ + struct virtio_console *virtcons = container_of(cdev, struct virtio_console, cdev); + + return virtqueue_poll(virtcons->in_vq, virtcons->in_vq->last_used_idx); +} + +static int virtcons_getc(struct console_device *cdev) +{ + struct virtio_console *virtcons = container_of(cdev, struct virtio_console, cdev); + char *in; + int ch; + + in = virtqueue_get_buf(virtcons->in_vq, NULL); + if (!in) + BUG(); + + ch = *in; + + add_inbuf(virtcons); + + return ch; +} + +static int virtcons_probe(struct virtio_device *vdev) +{ + struct virtqueue *vqs[2]; + struct virtio_console *virtcons; + int err; + + if (have_one) { + /* Neither multiport consoles (one virtio_device for multiple consoles) + * nor multiple consoles (one virtio_device per each console + * is supported. I would've expected: + * -chardev socket,path=/tmp/bar,server,nowait,id=bar \ + * -device virtconsole,chardev=bar,name=console.bar \ + * -device virtio-serial-device \ + * -chardev socket,path=/tmp/baz,server,nowait,id=baz \ + * -device virtconsole,chardev=baz,name=console.baz \ + * to just work, but it doesn't + */ + dev_warn(&vdev->dev, + "Multiple virtio-console devices not supported yet\n"); + return -EEXIST; + } + + /* Find the queues. */ + err = virtio_find_vqs(vdev, 2, vqs); + if (err) + return err; + + virtcons = xzalloc(sizeof(*virtcons)); + + virtcons->in_vq = vqs[0]; + virtcons->out_vq = vqs[1]; + + /* Register the input buffer the first time. */ + add_inbuf(virtcons); + + virtcons->cdev.dev = &vdev->dev; + virtcons->cdev.tstc = virtcons_tstc; + virtcons->cdev.getc = virtcons_getc; + virtcons->cdev.putc = virtcons_putc; + + have_one = true; + + return console_register(&virtcons->cdev); +} + +static struct virtio_device_id id_table[] = { + { VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID }, + { 0 }, +}; + +static struct virtio_driver virtio_console = { + .driver.name = "virtio_console", + .id_table = id_table, + .probe = virtcons_probe, +}; +device_virtio_driver(virtio_console); + +MODULE_DESCRIPTION("Virtio console driver"); +MODULE_LICENSE("GPL"); diff --git a/include/uapi/linux/virtio_console.h b/include/uapi/linux/virtio_console.h new file mode 100644 index 000000000000..7e6ec2ff0560 --- /dev/null +++ b/include/uapi/linux/virtio_console.h @@ -0,0 +1,78 @@ +/* + * This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so + * anyone can use the definitions to implement compatible drivers/servers: + * + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of IBM nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * Copyright (C) Red Hat, Inc., 2009, 2010, 2011 + * Copyright (C) Amit Shah , 2009, 2010, 2011 + */ +#ifndef _UAPI_LINUX_VIRTIO_CONSOLE_H +#define _UAPI_LINUX_VIRTIO_CONSOLE_H +#include +#include +#include +#include + +/* Feature bits */ +#define VIRTIO_CONSOLE_F_SIZE 0 /* Does host provide console size? */ +#define VIRTIO_CONSOLE_F_MULTIPORT 1 /* Does host provide multiple ports? */ +#define VIRTIO_CONSOLE_F_EMERG_WRITE 2 /* Does host support emergency write? */ + +#define VIRTIO_CONSOLE_BAD_ID (~(__u32)0) + +struct virtio_console_config { + /* colums of the screens */ + __virtio16 cols; + /* rows of the screens */ + __virtio16 rows; + /* max. number of ports this device can hold */ + __virtio32 max_nr_ports; + /* emergency write register */ + __virtio32 emerg_wr; +} __attribute__((packed)); + +/* + * A message that's passed between the Host and the Guest for a + * particular port. + */ +struct virtio_console_control { + __virtio32 id; /* Port number */ + __virtio16 event; /* The kind of control event (see below) */ + __virtio16 value; /* Extra information for the key */ +}; + +/* Some events for control messages */ +#define VIRTIO_CONSOLE_DEVICE_READY 0 +#define VIRTIO_CONSOLE_PORT_ADD 1 +#define VIRTIO_CONSOLE_PORT_REMOVE 2 +#define VIRTIO_CONSOLE_PORT_READY 3 +#define VIRTIO_CONSOLE_CONSOLE_PORT 4 +#define VIRTIO_CONSOLE_RESIZE 5 +#define VIRTIO_CONSOLE_PORT_OPEN 6 +#define VIRTIO_CONSOLE_PORT_NAME 7 + + +#endif /* _UAPI_LINUX_VIRTIO_CONSOLE_H */ -- 2.30.0 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox