drivers/char/virtio_console.c - SHIFTPHONES/kernel/common - Gitiles

 /*
  * 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/list.h>
 #include <linux/spinlock.h>
 #include <linux/virtio.h>
 #include <linux/virtio_console.h>
 #include "hvc_console.h"

 /*
  * This is a global struct for storing common data for all the devices
  * this driver handles.
  *
  * Mainly, it has a linked list for all the consoles in one place so
  * that callbacks from hvc for get_chars(), put_chars() work properly
  * across multiple devices and multiple ports per device.
  */
 struct ports_driver_data {
 	/*
 	 * This is used to keep track of the number of hvc consoles
 	 * spawned by this driver.  This number is given as the first
 	 * argument to hvc_alloc().  To correctly map an initial
 	 * console spawned via hvc_instantiate to the console being
 	 * hooked up via hvc_alloc, we need to pass the same vtermno.
 	 *
 	 * We also just assume the first console being initialised was
 	 * the first one that got used as the initial console.
 	 */
 	unsigned int next_vtermno;

 	/* All the console devices handled by this driver */
 	struct list_head consoles;
 };
 static struct ports_driver_data pdrvdata;

 DEFINE_SPINLOCK(pdrvdata_lock);

 struct port_buffer {
 	char *buf;

 	/* size of the buffer in *buf above */
 	size_t size;

 	/* used length of the buffer */
 	size_t len;
 	/* offset in the buf from which to consume data */
 	size_t offset;
 };

 struct port {
 	struct virtqueue *in_vq, *out_vq;
 	struct virtio_device *vdev;

 	/* The current buffer from which data has to be fed to readers */
 	struct port_buffer *inbuf;

 	/* For console ports, hvc != NULL and these are valid. */
 	/* The hvc device */
 	struct hvc_struct *hvc;

 	/* We'll place all consoles in a list in the pdrvdata struct */
 	struct list_head list;

 	/* Our vterm number. */
 	u32 vtermno;
 };

 /* This is the very early arch-specified put chars function. */
 static int (*early_put_chars)(u32, const char *, int);

 static struct port *find_port_by_vtermno(u32 vtermno)
 {
 	struct port *port;
 	unsigned long flags;

 	spin_lock_irqsave(&pdrvdata_lock, flags);
 	list_for_each_entry(port, &pdrvdata.consoles, list) {
 		if (port->vtermno == vtermno)
 			goto out;
 	}
 	port = NULL;
 out:
 	spin_unlock_irqrestore(&pdrvdata_lock, flags);
 	return port;
 }

 static void free_buf(struct port_buffer *buf)
 {
 	kfree(buf->buf);
 	kfree(buf);
 }

 static struct port_buffer *alloc_buf(size_t buf_size)
 {
 	struct port_buffer *buf;

 	buf = kmalloc(sizeof(*buf), GFP_KERNEL);
 	if (!buf)
 		goto fail;
 	buf->buf = kzalloc(buf_size, GFP_KERNEL);
 	if (!buf->buf)
 		goto free_buf;
 	buf->len = 0;
 	buf->offset = 0;
 	buf->size = buf_size;
 	return buf;

 free_buf:
 	kfree(buf);
 fail:
 	return NULL;
 }

 /* Callers should take appropriate locks */
 static void *get_inbuf(struct port *port)
 {
 	struct port_buffer *buf;
 	struct virtqueue *vq;
 	unsigned int len;

 	vq = port->in_vq;
 	buf = vq->vq_ops->get_buf(vq, &len);
 	if (buf) {
 		buf->len = len;
 		buf->offset = 0;
 	}
 	return buf;
 }

 /*
  * Create a scatter-gather list representing our input buffer and put
  * it in the queue.
  *
  * Callers should take appropriate locks.
  */
 static void add_inbuf(struct virtqueue *vq, struct port_buffer *buf)
 {
 	struct scatterlist sg[1];
 	sg_init_one(sg, buf->buf, buf->size);

 	if (vq->vq_ops->add_buf(vq, sg, 0, 1, buf) < 0)
 		BUG();
 	vq->vq_ops->kick(vq);
 }

 /*
  * 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];
 	struct port *port;
 	unsigned int len;

 	port = find_port_by_vtermno(vtermno);
 	if (!port)
 		return 0;

 	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);

 	/* This shouldn't fail: if it does, we lose chars. */
 	if (port->out_vq->vq_ops->add_buf(port->out_vq, sg, 1, 0, port) >= 0) {
 		/* Tell Host to go! */
 		port->out_vq->vq_ops->kick(port->out_vq);
 		while (!port->out_vq->vq_ops->get_buf(port->out_vq, &len))
 			cpu_relax();
 	}

 	/* We're expected to return the amount of data we wrote: all of it. */
 	return count;
 }

 /*
  * 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)
 {
 	struct port *port;


 	port = find_port_by_vtermno(vtermno);
 	if (!port)
 		return 0;

 	/* If we don't have an input queue yet, we can't get input. */
 	BUG_ON(!port->in_vq);

 	/* No more in buffer?  See if they've (re)used it. */
 	if (port->inbuf->offset == port->inbuf->len) {
 		if (!get_inbuf(port))
 			return 0;
 	}

 	/* You want more than we have to give?  Well, try wanting less! */
 	if (port->inbuf->offset + count > port->inbuf->len)
 		count = port->inbuf->len - port->inbuf->offset;

 	/* Copy across to their buffer and increment offset. */
 	memcpy(buf, port->inbuf->buf + port->inbuf->offset, count);
 	port->inbuf->offset += count;

 	/* Finished?  Re-register buffer so Host will use it again. */
 	if (port->inbuf->offset == port->inbuf->len)
 		add_inbuf(port->in_vq, port->inbuf);

 	return count;
 }

 /*
  * virtio console configuration. This supports:
  * - console resize
  */
 static void virtcons_apply_config(struct virtio_device *dev)
 {
 	struct port *port = dev->priv;
 	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(port->hvc, ws);
 	}
 }

 /* We set the configuration at this point, since we now have a tty */
 static int notifier_add_vio(struct hvc_struct *hp, int data)
 {
 	struct port *port;

 	port = find_port_by_vtermno(hp->vtermno);
 	if (!port)
 		return -EINVAL;

 	hp->irq_requested = 1;
 	virtcons_apply_config(port->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)
 {
 	struct port *port = vq->vdev->priv;

 	if (hvc_poll(port->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);
 }

 static struct port *__devinit add_port(u32 vtermno)
 {
 	struct port *port;

 	port = kmalloc(sizeof(*port), GFP_KERNEL);
 	if (!port)
 		return NULL;

 	port->inbuf = alloc_buf(PAGE_SIZE);
 	if (!port->inbuf) {
 		kfree(port);
 		return NULL;
 	}
 	port->hvc = NULL;
 	port->vtermno = vtermno;
 	return port;
 }

 static void free_port(struct port *port)
 {
 	free_buf(port->inbuf);
 	kfree(port);
 }

 /*
  * 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 *vdev)
 {
 	vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
 	const char *names[] = { "input", "output" };
 	struct virtqueue *vqs[2];
 	struct port *port;
 	int err;

 	port = add_port(pdrvdata.next_vtermno);
 	if (!port) {
 		err = -ENOMEM;
 		goto fail;
 	}

 	/* Attach this port to this virtio_device, and vice-versa. */
 	port->vdev = vdev;
 	vdev->priv = port;

 	/* Find the queues. */
 	err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
 	if (err)
 		goto free;

 	port->in_vq = vqs[0];
 	port->out_vq = vqs[1];

 	/*
 	 * The first argument of hvc_alloc() is the virtual console
 	 * number.  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.
 	 */
 	port->hvc = hvc_alloc(port->vtermno, 0, &hv_ops, PAGE_SIZE);
 	if (IS_ERR(port->hvc)) {
 		err = PTR_ERR(port->hvc);
 		goto free_vqs;
 	}

 	/* Add to vtermno list. */
 	spin_lock_irq(&pdrvdata_lock);
 	pdrvdata.next_vtermno++;
 	list_add(&port->list, &pdrvdata.consoles);
 	spin_unlock_irq(&pdrvdata_lock);

 	/* Register the input buffer the first time. */
 	add_inbuf(port->in_vq, port->inbuf);

 	/* Start using the new console output. */
 	early_put_chars = NULL;
 	return 0;

 free_vqs:
 	vdev->config->del_vqs(vdev);
 free:
 	free_port(port);
 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)
 {
 	INIT_LIST_HEAD(&pdrvdata.consoles);

 	return register_virtio_driver(&virtio_console);
 }
 module_init(init);

 MODULE_DEVICE_TABLE(virtio, id_table);
 MODULE_DESCRIPTION("Virtio console driver");
 MODULE_LICENSE("GPL");
	/*
	* 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/list.h>
	#include <linux/spinlock.h>
	#include <linux/virtio.h>
	#include <linux/virtio_console.h>
	#include "hvc_console.h"

	/*
	* This is a global struct for storing common data for all the devices
	* this driver handles.
	*
	* Mainly, it has a linked list for all the consoles in one place so
	* that callbacks from hvc for get_chars(), put_chars() work properly
	* across multiple devices and multiple ports per device.
	*/
	struct ports_driver_data {
	/*
	* This is used to keep track of the number of hvc consoles
	* spawned by this driver. This number is given as the first
	* argument to hvc_alloc(). To correctly map an initial
	* console spawned via hvc_instantiate to the console being
	* hooked up via hvc_alloc, we need to pass the same vtermno.
	*
	* We also just assume the first console being initialised was
	* the first one that got used as the initial console.
	*/
	unsigned int next_vtermno;

	/* All the console devices handled by this driver */
	struct list_head consoles;
	};
	static struct ports_driver_data pdrvdata;

	DEFINE_SPINLOCK(pdrvdata_lock);

	struct port_buffer {
	char *buf;

	/* size of the buffer in buf above /
	size_t size;

	/* used length of the buffer */
	size_t len;
	/* offset in the buf from which to consume data */
	size_t offset;
	};

	struct port {
	struct virtqueue in_vq, out_vq;
	struct virtio_device *vdev;

	/* The current buffer from which data has to be fed to readers */
	struct port_buffer *inbuf;

	/* For console ports, hvc != NULL and these are valid. */
	/* The hvc device */
	struct hvc_struct *hvc;

	/* We'll place all consoles in a list in the pdrvdata struct */
	struct list_head list;

	/* Our vterm number. */
	u32 vtermno;
	};

	/* This is the very early arch-specified put chars function. */
	static int (early_put_chars)(u32, const char , int);

	static struct port *find_port_by_vtermno(u32 vtermno)
	{
	struct port *port;
	unsigned long flags;

	spin_lock_irqsave(&pdrvdata_lock, flags);
	list_for_each_entry(port, &pdrvdata.consoles, list) {
	if (port->vtermno == vtermno)
	goto out;
	}
	port = NULL;
	out:
	spin_unlock_irqrestore(&pdrvdata_lock, flags);
	return port;
	}

	static void free_buf(struct port_buffer *buf)
	{
	kfree(buf->buf);
	kfree(buf);
	}

	static struct port_buffer *alloc_buf(size_t buf_size)
	{
	struct port_buffer *buf;

	buf = kmalloc(sizeof(*buf), GFP_KERNEL);
	if (!buf)
	goto fail;
	buf->buf = kzalloc(buf_size, GFP_KERNEL);
	if (!buf->buf)
	goto free_buf;
	buf->len = 0;
	buf->offset = 0;
	buf->size = buf_size;
	return buf;

	free_buf:
	kfree(buf);
	fail:
	return NULL;
	}

	/* Callers should take appropriate locks */
	static void get_inbuf(struct port port)
	{
	struct port_buffer *buf;
	struct virtqueue *vq;
	unsigned int len;

	vq = port->in_vq;
	buf = vq->vq_ops->get_buf(vq, &len);
	if (buf) {
	buf->len = len;
	buf->offset = 0;
	}
	return buf;
	}

	/*
	* Create a scatter-gather list representing our input buffer and put
	* it in the queue.
	*
	* Callers should take appropriate locks.
	*/
	static void add_inbuf(struct virtqueue vq, struct port_buffer buf)
	{
	struct scatterlist sg[1];
	sg_init_one(sg, buf->buf, buf->size);

	if (vq->vq_ops->add_buf(vq, sg, 0, 1, buf) < 0)
	BUG();
	vq->vq_ops->kick(vq);
	}

	/*
	* 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];
	struct port *port;
	unsigned int len;

	port = find_port_by_vtermno(vtermno);
	if (!port)
	return 0;

	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);

	/* This shouldn't fail: if it does, we lose chars. */
	if (port->out_vq->vq_ops->add_buf(port->out_vq, sg, 1, 0, port) >= 0) {
	/* Tell Host to go! */
	port->out_vq->vq_ops->kick(port->out_vq);
	while (!port->out_vq->vq_ops->get_buf(port->out_vq, &len))
	cpu_relax();
	}

	/* We're expected to return the amount of data we wrote: all of it. */
	return count;
	}

	/*
	* 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)
	{
	struct port *port;


	port = find_port_by_vtermno(vtermno);
	if (!port)
	return 0;

	/* If we don't have an input queue yet, we can't get input. */
	BUG_ON(!port->in_vq);

	/* No more in buffer? See if they've (re)used it. */
	if (port->inbuf->offset == port->inbuf->len) {
	if (!get_inbuf(port))
	return 0;
	}

	/* You want more than we have to give? Well, try wanting less! */
	if (port->inbuf->offset + count > port->inbuf->len)
	count = port->inbuf->len - port->inbuf->offset;

	/* Copy across to their buffer and increment offset. */
	memcpy(buf, port->inbuf->buf + port->inbuf->offset, count);
	port->inbuf->offset += count;

	/* Finished? Re-register buffer so Host will use it again. */
	if (port->inbuf->offset == port->inbuf->len)
	add_inbuf(port->in_vq, port->inbuf);

	return count;
	}

	/*
	* virtio console configuration. This supports:
	* - console resize
	*/
	static void virtcons_apply_config(struct virtio_device *dev)
	{
	struct port *port = dev->priv;
	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(port->hvc, ws);
	}
	}

	/* We set the configuration at this point, since we now have a tty */
	static int notifier_add_vio(struct hvc_struct *hp, int data)
	{
	struct port *port;

	port = find_port_by_vtermno(hp->vtermno);
	if (!port)
	return -EINVAL;

	hp->irq_requested = 1;
	virtcons_apply_config(port->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)
	{
	struct port *port = vq->vdev->priv;

	if (hvc_poll(port->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);
	}

	static struct port *__devinit add_port(u32 vtermno)
	{
	struct port *port;

	port = kmalloc(sizeof(*port), GFP_KERNEL);
	if (!port)
	return NULL;

	port->inbuf = alloc_buf(PAGE_SIZE);
	if (!port->inbuf) {
	kfree(port);
	return NULL;
	}
	port->hvc = NULL;
	port->vtermno = vtermno;
	return port;
	}

	static void free_port(struct port *port)
	{
	free_buf(port->inbuf);
	kfree(port);
	}

	/*
	* 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 *vdev)
	{
	vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
	const char *names[] = { "input", "output" };
	struct virtqueue *vqs[2];
	struct port *port;
	int err;

	port = add_port(pdrvdata.next_vtermno);
	if (!port) {
	err = -ENOMEM;
	goto fail;
	}

	/* Attach this port to this virtio_device, and vice-versa. */
	port->vdev = vdev;
	vdev->priv = port;

	/* Find the queues. */
	err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
	if (err)
	goto free;

	port->in_vq = vqs[0];
	port->out_vq = vqs[1];

	/*
	* The first argument of hvc_alloc() is the virtual console
	* number. 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.
	*/
	port->hvc = hvc_alloc(port->vtermno, 0, &hv_ops, PAGE_SIZE);
	if (IS_ERR(port->hvc)) {
	err = PTR_ERR(port->hvc);
	goto free_vqs;
	}

	/* Add to vtermno list. */
	spin_lock_irq(&pdrvdata_lock);
	pdrvdata.next_vtermno++;
	list_add(&port->list, &pdrvdata.consoles);
	spin_unlock_irq(&pdrvdata_lock);

	/* Register the input buffer the first time. */
	add_inbuf(port->in_vq, port->inbuf);

	/* Start using the new console output. */
	early_put_chars = NULL;
	return 0;

	free_vqs:
	vdev->config->del_vqs(vdev);
	free:
	free_port(port);
	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)
	{
	INIT_LIST_HEAD(&pdrvdata.consoles);

	return register_virtio_driver(&virtio_console);
	}
	module_init(init);

	MODULE_DEVICE_TABLE(virtio, id_table);
	MODULE_DESCRIPTION("Virtio console driver");
	MODULE_LICENSE("GPL");