/*
* Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/err.h>
#include <linux/init.h>
#include <linux/virtio.h>
#include <linux/virtio_console.h>
#include "hvc_console.h"
static struct virtqueue *in_vq, *out_vq;
static struct virtio_device *vdev;
/* This is our input buffer, and how much data is left in it. */
static unsigned int in_len;
static char *in, *inbuf;
/* The hvc device */
static struct hvc_struct *hvc;
/* This is the very early arch-specified put chars function. */
static int (*early_put_chars)(u32, const char *, int);
/*
* 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 int put_chars(u32 vtermno, const char *buf, int count)
{
struct scatterlist sg[1];
unsigned int len;
if (unlikely(early_put_chars))
return early_put_chars(vtermno, buf, count);
/* This is a convenient routine to initialize a single-elem sg list */
sg_init_one(sg, buf, 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 (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) >= 0) {
/* Tell Host to go! */
out_vq->vq_ops->kick(out_vq);
/* Chill out until it's done with the buffer. */
while (!out_vq->vq_ops->get_buf(out_vq, &len))
cpu_relax();
}
/* We're expected to return the amount of data we wrote: all of it. */
return count;
}
/*
* Create a scatter-gather list representing our input buffer and put
* it in the queue.
*/
static void add_inbuf(void)
{
struct scatterlist sg[1];
sg_init_one(sg, inbuf, PAGE_SIZE);
/* We should always be able to add one buffer to an empty queue. */
if (in_vq->vq_ops->add_buf(in_vq, sg, 0, 1, inbuf) < 0)
BUG();
in_vq->vq_ops->kick(in_vq);
}
/*
* get_chars() is the callback from the hvc_console infrastructure
* when an interrupt is received.
*
* Most of the code deals with the fact that the hvc_console()
* infrastructure only asks us for 16 bytes at a time. We keep
* in_offset and in_used fields for partially-filled buffers.
*/
static int get_chars(u32 vtermno, char *buf, int count)
{
/* If we don't have an input queue yet, we can't get input. */
BUG_ON(!in_vq);
/* No buffer? Try to get one. */
if (!in_len) {
in = in_vq->vq_ops->get_buf(in_vq, &in_len);
if (!in)
return 0;
}
/* You want more than we have to give? Well, try wanting less! */
if (in_len < count)
count = in_len;
/* Copy across to their buffer and increment offset. */
memcpy(buf, in, count);
in += count;
in_len -= count;
/* Finished? Re-register buffer so Host will use it again. */
if (in_len == 0)
add_inbuf();
return count;
}
/*
* virtio console configuration. This supports:
* - console resize
*/
static void virtcons_apply_config(struct virtio_device *dev)
{
struct winsize ws;
if (virtio_has_feature(dev, VIRTIO_CONSOLE_F_SIZE)) {
dev->config->get(dev,
offsetof(struct virtio_console_config, cols),
&ws.ws_col, sizeof(u16));
dev->config->get(dev,
offsetof(struct virtio_console_config, rows),
&ws.ws_row, sizeof(u16));
hvc_resize(hvc, ws);
}
}
/*
* we support only one console, the hvc struct is a global var We set
* the configuration at this point, since we now have a tty
*/
static int notifier_add_vio(struct hvc_struct *hp, int data)
{
hp->irq_requested = 1;
virtcons_apply_config(vdev);
return 0;
}
static void notifier_del_vio(struct hvc_struct *hp, int data)
{
hp->irq_requested = 0;
}
static void hvc_handle_input(struct virtqueue *vq)
{
if (hvc_poll(hvc))
hvc_kick();
}
/* The operations for the console. */
static const struct hv_ops hv_ops = {
.get_chars = get_chars,
.put_chars = put_chars,
.notifier_add = notifier_add_vio,
.notifier_del = notifier_del_vio,
.notifier_hangup = notifier_del_vio,
};
/*
* Console drivers are initialized very early so boot messages can go
* out, so we do things slightly differently from the generic virtio
* initialization of the net and block drivers.
*
* At this stage, the console is output-only. It's too early to set
* up a virtqueue, so we let the drivers do some boutique early-output
* thing.
*/
int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
{
early_put_chars = put_chars;
return hvc_instantiate(0, 0, &hv_ops);
}
/*
* Once we're further in boot, we get probed like any other virtio
* device. At this stage we set up the output virtqueue.
*
* To set up and manage our virtual console, we call hvc_alloc().
* Since we never remove the console device we never need this pointer
* again.
*
* Finally we put our input buffer in the input queue, ready to
* receive.
*/
static int __devinit virtcons_probe(struct virtio_device *dev)
{
vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
const char *names[] = { "input", "output" };
struct virtqueue *vqs[2];
int err;
vdev = dev;
/* This is the scratch page we use to receive console input */
inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!inbuf) {
err = -ENOMEM;
goto fail;
}
/* Find the queues. */
err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
if (err)
goto free;
in_vq = vqs[0];
out_vq = vqs[1];
/*
* The first argument of hvc_alloc() is the virtual console
* number, so we use zero. The second argument is the
* parameter for the notification mechanism (like irq
* number). We currently leave this as zero, virtqueues have
* implicit notifications.
*
* The third argument is a "struct hv_ops" containing the
* put_chars(), get_chars(), notifier_add() and notifier_del()
* pointers. The final argument is the output buffer size: we
* can do any size, so we put PAGE_SIZE here.
*/
hvc = hvc_alloc(0, 0, &hv_ops, PAGE_SIZE);
if (IS_ERR(hvc)) {
err = PTR_ERR(hvc);
goto free_vqs;
}
/* Register the input buffer the first time. */
add_inbuf();
/* Start using the new console output. */
early_put_chars = NULL;
return 0;
free_vqs:
vdev->config->del_vqs(vdev);
free:
kfree(inbuf);
fail:
return err;
}
static struct virtio_device_id id_table[] = {
{ VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID },
{ 0 },
};
static unsigned int features[] = {
VIRTIO_CONSOLE_F_SIZE,
};
static struct virtio_driver virtio_console = {
.feature_table = features,
.feature_table_size = ARRAY_SIZE(features),
.driver.name = KBUILD_MODNAME,
.driver.owner = THIS_MODULE,
.id_table = id_table,
.probe = virtcons_probe,
.config_changed = virtcons_apply_config,
};
static int __init init(void)
{
return register_virtio_driver(&virtio_console);
}
module_init(init);
MODULE_DEVICE_TABLE(virtio, id_table);
MODULE_DESCRIPTION("Virtio console driver");
MODULE_LICENSE("GPL");
