Merge branch 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh...
authorLinus Torvalds <torvalds@linux-foundation.org>
Thu, 10 Feb 2011 20:19:58 +0000 (12:19 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 10 Feb 2011 20:19:58 +0000 (12:19 -0800)
* 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6:
  serial: bfin_5xx: split uart RX lock from uart port lock to avoid deadlock
  68360serial: Plumb in rs_360_get_icount()
  n_gsm: copy mtu over when configuring via ioctl interface
  virtio: console: Move file back to drivers/char/

1  2 
drivers/char/virtio_console.c

index 0000000000000000000000000000000000000000,5feadeefef3f82daa12340c5b29886aef585a04e..490393186338dae5b8a7a7804923b801a381263a
mode 000000,100644..100644
--- /dev/null
@@@ -1,0 -1,1838 +1,1850 @@@
 - * Copyright (C) 2009, 2010 Red Hat, Inc.
+ /*
+  * Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation
 -      io_callbacks[j + 1] = NULL;
++ * Copyright (C) 2009, 2010, 2011 Red Hat, Inc.
++ * Copyright (C) 2009, 2010, 2011 Amit Shah <amit.shah@redhat.com>
+  *
+  * 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/cdev.h>
+ #include <linux/debugfs.h>
+ #include <linux/device.h>
+ #include <linux/err.h>
+ #include <linux/fs.h>
+ #include <linux/init.h>
+ #include <linux/list.h>
+ #include <linux/poll.h>
+ #include <linux/sched.h>
+ #include <linux/slab.h>
+ #include <linux/spinlock.h>
+ #include <linux/virtio.h>
+ #include <linux/virtio_console.h>
+ #include <linux/wait.h>
+ #include <linux/workqueue.h>
+ #include "../tty/hvc/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 {
+       /* Used for registering chardevs */
+       struct class *class;
+       /* Used for exporting per-port information to debugfs */
+       struct dentry *debugfs_dir;
+       /* List of all the devices we're handling */
+       struct list_head portdevs;
+       /* Number of devices this driver is handling */
+       unsigned int index;
+       /*
+        * 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);
+ /* This struct holds information that's relevant only for console ports */
+ struct console {
+       /* We'll place all consoles in a list in the pdrvdata struct */
+       struct list_head list;
+       /* The hvc device associated with this console port */
+       struct hvc_struct *hvc;
+       /* The size of the console */
+       struct winsize ws;
+       /*
+        * This number identifies the number that we used to register
+        * with hvc in hvc_instantiate() and hvc_alloc(); this is the
+        * number passed on by the hvc callbacks to us to
+        * differentiate between the other console ports handled by
+        * this driver
+        */
+       u32 vtermno;
+ };
+ 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;
+ };
+ /*
+  * This is a per-device struct that stores data common to all the
+  * ports for that device (vdev->priv).
+  */
+ struct ports_device {
+       /* Next portdev in the list, head is in the pdrvdata struct */
+       struct list_head list;
+       /*
+        * Workqueue handlers where we process deferred work after
+        * notification
+        */
+       struct work_struct control_work;
+       struct list_head ports;
+       /* To protect the list of ports */
+       spinlock_t ports_lock;
+       /* To protect the vq operations for the control channel */
+       spinlock_t cvq_lock;
+       /* The current config space is stored here */
+       struct virtio_console_config config;
+       /* The virtio device we're associated with */
+       struct virtio_device *vdev;
+       /*
+        * A couple of virtqueues for the control channel: one for
+        * guest->host transfers, one for host->guest transfers
+        */
+       struct virtqueue *c_ivq, *c_ovq;
+       /* Array of per-port IO virtqueues */
+       struct virtqueue **in_vqs, **out_vqs;
+       /* Used for numbering devices for sysfs and debugfs */
+       unsigned int drv_index;
+       /* Major number for this device.  Ports will be created as minors. */
+       int chr_major;
+ };
+ /* This struct holds the per-port data */
+ struct port {
+       /* Next port in the list, head is in the ports_device */
+       struct list_head list;
+       /* Pointer to the parent virtio_console device */
+       struct ports_device *portdev;
+       /* The current buffer from which data has to be fed to readers */
+       struct port_buffer *inbuf;
+       /*
+        * To protect the operations on the in_vq associated with this
+        * port.  Has to be a spinlock because it can be called from
+        * interrupt context (get_char()).
+        */
+       spinlock_t inbuf_lock;
+       /* Protect the operations on the out_vq. */
+       spinlock_t outvq_lock;
+       /* The IO vqs for this port */
+       struct virtqueue *in_vq, *out_vq;
+       /* File in the debugfs directory that exposes this port's information */
+       struct dentry *debugfs_file;
+       /*
+        * The entries in this struct will be valid if this port is
+        * hooked up to an hvc console
+        */
+       struct console cons;
+       /* Each port associates with a separate char device */
+       struct cdev *cdev;
+       struct device *dev;
+       /* Reference-counting to handle port hot-unplugs and file operations */
+       struct kref kref;
+       /* A waitqueue for poll() or blocking read operations */
+       wait_queue_head_t waitqueue;
+       /* The 'name' of the port that we expose via sysfs properties */
+       char *name;
+       /* We can notify apps of host connect / disconnect events via SIGIO */
+       struct fasync_struct *async_queue;
+       /* The 'id' to identify the port with the Host */
+       u32 id;
+       bool outvq_full;
+       /* Is the host device open */
+       bool host_connected;
+       /* We should allow only one process to open a port */
+       bool guest_connected;
+ };
+ /* 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;
+       struct console *cons;
+       unsigned long flags;
+       spin_lock_irqsave(&pdrvdata_lock, flags);
+       list_for_each_entry(cons, &pdrvdata.consoles, list) {
+               if (cons->vtermno == vtermno) {
+                       port = container_of(cons, struct port, cons);
+                       goto out;
+               }
+       }
+       port = NULL;
+ out:
+       spin_unlock_irqrestore(&pdrvdata_lock, flags);
+       return port;
+ }
+ static struct port *find_port_by_devt_in_portdev(struct ports_device *portdev,
+                                                dev_t dev)
+ {
+       struct port *port;
+       unsigned long flags;
+       spin_lock_irqsave(&portdev->ports_lock, flags);
+       list_for_each_entry(port, &portdev->ports, list)
+               if (port->cdev->dev == dev)
+                       goto out;
+       port = NULL;
+ out:
+       spin_unlock_irqrestore(&portdev->ports_lock, flags);
+       return port;
+ }
+ static struct port *find_port_by_devt(dev_t dev)
+ {
+       struct ports_device *portdev;
+       struct port *port;
+       unsigned long flags;
+       spin_lock_irqsave(&pdrvdata_lock, flags);
+       list_for_each_entry(portdev, &pdrvdata.portdevs, list) {
+               port = find_port_by_devt_in_portdev(portdev, dev);
+               if (port)
+                       goto out;
+       }
+       port = NULL;
+ out:
+       spin_unlock_irqrestore(&pdrvdata_lock, flags);
+       return port;
+ }
+ static struct port *find_port_by_id(struct ports_device *portdev, u32 id)
+ {
+       struct port *port;
+       unsigned long flags;
+       spin_lock_irqsave(&portdev->ports_lock, flags);
+       list_for_each_entry(port, &portdev->ports, list)
+               if (port->id == id)
+                       goto out;
+       port = NULL;
+ out:
+       spin_unlock_irqrestore(&portdev->ports_lock, flags);
+       return port;
+ }
+ static struct port *find_port_by_vq(struct ports_device *portdev,
+                                   struct virtqueue *vq)
+ {
+       struct port *port;
+       unsigned long flags;
+       spin_lock_irqsave(&portdev->ports_lock, flags);
+       list_for_each_entry(port, &portdev->ports, list)
+               if (port->in_vq == vq || port->out_vq == vq)
+                       goto out;
+       port = NULL;
+ out:
+       spin_unlock_irqrestore(&portdev->ports_lock, flags);
+       return port;
+ }
+ static bool is_console_port(struct port *port)
+ {
+       if (port->cons.hvc)
+               return true;
+       return false;
+ }
+ static inline bool use_multiport(struct ports_device *portdev)
+ {
+       /*
+        * This condition can be true when put_chars is called from
+        * early_init
+        */
+       if (!portdev->vdev)
+               return 0;
+       return portdev->vdev->features[0] & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
+ }
+ 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 = virtqueue_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 int add_inbuf(struct virtqueue *vq, struct port_buffer *buf)
+ {
+       struct scatterlist sg[1];
+       int ret;
+       sg_init_one(sg, buf->buf, buf->size);
+       ret = virtqueue_add_buf(vq, sg, 0, 1, buf);
+       virtqueue_kick(vq);
+       return ret;
+ }
+ /* Discard any unread data this port has. Callers lockers. */
+ static void discard_port_data(struct port *port)
+ {
+       struct port_buffer *buf;
+       struct virtqueue *vq;
+       unsigned int len;
+       int ret;
+       vq = port->in_vq;
+       if (port->inbuf)
+               buf = port->inbuf;
+       else
+               buf = virtqueue_get_buf(vq, &len);
+       ret = 0;
+       while (buf) {
+               if (add_inbuf(vq, buf) < 0) {
+                       ret++;
+                       free_buf(buf);
+               }
+               buf = virtqueue_get_buf(vq, &len);
+       }
+       port->inbuf = NULL;
+       if (ret)
+               dev_warn(port->dev, "Errors adding %d buffers back to vq\n",
+                        ret);
+ }
+ static bool port_has_data(struct port *port)
+ {
+       unsigned long flags;
+       bool ret;
+       spin_lock_irqsave(&port->inbuf_lock, flags);
+       if (port->inbuf) {
+               ret = true;
+               goto out;
+       }
+       port->inbuf = get_inbuf(port);
+       if (port->inbuf) {
+               ret = true;
+               goto out;
+       }
+       ret = false;
+ out:
+       spin_unlock_irqrestore(&port->inbuf_lock, flags);
+       return ret;
+ }
+ static ssize_t __send_control_msg(struct ports_device *portdev, u32 port_id,
+                                 unsigned int event, unsigned int value)
+ {
+       struct scatterlist sg[1];
+       struct virtio_console_control cpkt;
+       struct virtqueue *vq;
+       unsigned int len;
+       if (!use_multiport(portdev))
+               return 0;
+       cpkt.id = port_id;
+       cpkt.event = event;
+       cpkt.value = value;
+       vq = portdev->c_ovq;
+       sg_init_one(sg, &cpkt, sizeof(cpkt));
+       if (virtqueue_add_buf(vq, sg, 1, 0, &cpkt) >= 0) {
+               virtqueue_kick(vq);
+               while (!virtqueue_get_buf(vq, &len))
+                       cpu_relax();
+       }
+       return 0;
+ }
+ static ssize_t send_control_msg(struct port *port, unsigned int event,
+                               unsigned int value)
+ {
+       /* Did the port get unplugged before userspace closed it? */
+       if (port->portdev)
+               return __send_control_msg(port->portdev, port->id, event, value);
+       return 0;
+ }
+ /* Callers must take the port->outvq_lock */
+ static void reclaim_consumed_buffers(struct port *port)
+ {
+       void *buf;
+       unsigned int len;
+       while ((buf = virtqueue_get_buf(port->out_vq, &len))) {
+               kfree(buf);
+               port->outvq_full = false;
+       }
+ }
+ static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count,
+                       bool nonblock)
+ {
+       struct scatterlist sg[1];
+       struct virtqueue *out_vq;
+       ssize_t ret;
+       unsigned long flags;
+       unsigned int len;
+       out_vq = port->out_vq;
+       spin_lock_irqsave(&port->outvq_lock, flags);
+       reclaim_consumed_buffers(port);
+       sg_init_one(sg, in_buf, in_count);
+       ret = virtqueue_add_buf(out_vq, sg, 1, 0, in_buf);
+       /* Tell Host to go! */
+       virtqueue_kick(out_vq);
+       if (ret < 0) {
+               in_count = 0;
+               goto done;
+       }
+       if (ret == 0)
+               port->outvq_full = true;
+       if (nonblock)
+               goto done;
+       /*
+        * Wait till the host acknowledges it pushed out the data we
+        * sent.  This is done for data from the hvc_console; the tty
+        * operations are performed with spinlocks held so we can't
+        * sleep here.  An alternative would be to copy the data to a
+        * buffer and relax the spinning requirement.  The downside is
+        * we need to kmalloc a GFP_ATOMIC buffer each time the
+        * console driver writes something out.
+        */
+       while (!virtqueue_get_buf(out_vq, &len))
+               cpu_relax();
+ done:
+       spin_unlock_irqrestore(&port->outvq_lock, flags);
+       /*
+        * We're expected to return the amount of data we wrote -- all
+        * of it
+        */
+       return in_count;
+ }
+ /*
+  * Give out the data that's requested from the buffer that we have
+  * queued up.
+  */
+ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count,
+                           bool to_user)
+ {
+       struct port_buffer *buf;
+       unsigned long flags;
+       if (!out_count || !port_has_data(port))
+               return 0;
+       buf = port->inbuf;
+       out_count = min(out_count, buf->len - buf->offset);
+       if (to_user) {
+               ssize_t ret;
+               ret = copy_to_user(out_buf, buf->buf + buf->offset, out_count);
+               if (ret)
+                       return -EFAULT;
+       } else {
+               memcpy(out_buf, buf->buf + buf->offset, out_count);
+       }
+       buf->offset += out_count;
+       if (buf->offset == buf->len) {
+               /*
+                * We're done using all the data in this buffer.
+                * Re-queue so that the Host can send us more data.
+                */
+               spin_lock_irqsave(&port->inbuf_lock, flags);
+               port->inbuf = NULL;
+               if (add_inbuf(port->in_vq, buf) < 0)
+                       dev_warn(port->dev, "failed add_buf\n");
+               spin_unlock_irqrestore(&port->inbuf_lock, flags);
+       }
+       /* Return the number of bytes actually copied */
+       return out_count;
+ }
+ /* The condition that must be true for polling to end */
+ static bool will_read_block(struct port *port)
+ {
+       if (!port->guest_connected) {
+               /* Port got hot-unplugged. Let's exit. */
+               return false;
+       }
+       return !port_has_data(port) && port->host_connected;
+ }
+ static bool will_write_block(struct port *port)
+ {
+       bool ret;
+       if (!port->guest_connected) {
+               /* Port got hot-unplugged. Let's exit. */
+               return false;
+       }
+       if (!port->host_connected)
+               return true;
+       spin_lock_irq(&port->outvq_lock);
+       /*
+        * Check if the Host has consumed any buffers since we last
+        * sent data (this is only applicable for nonblocking ports).
+        */
+       reclaim_consumed_buffers(port);
+       ret = port->outvq_full;
+       spin_unlock_irq(&port->outvq_lock);
+       return ret;
+ }
+ static ssize_t port_fops_read(struct file *filp, char __user *ubuf,
+                             size_t count, loff_t *offp)
+ {
+       struct port *port;
+       ssize_t ret;
+       port = filp->private_data;
+       if (!port_has_data(port)) {
+               /*
+                * If nothing's connected on the host just return 0 in
+                * case of list_empty; this tells the userspace app
+                * that there's no connection
+                */
+               if (!port->host_connected)
+                       return 0;
+               if (filp->f_flags & O_NONBLOCK)
+                       return -EAGAIN;
+               ret = wait_event_interruptible(port->waitqueue,
+                                              !will_read_block(port));
+               if (ret < 0)
+                       return ret;
+       }
+       /* Port got hot-unplugged. */
+       if (!port->guest_connected)
+               return -ENODEV;
+       /*
+        * We could've received a disconnection message while we were
+        * waiting for more data.
+        *
+        * This check is not clubbed in the if() statement above as we
+        * might receive some data as well as the host could get
+        * disconnected after we got woken up from our wait.  So we
+        * really want to give off whatever data we have and only then
+        * check for host_connected.
+        */
+       if (!port_has_data(port) && !port->host_connected)
+               return 0;
+       return fill_readbuf(port, ubuf, count, true);
+ }
+ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
+                              size_t count, loff_t *offp)
+ {
+       struct port *port;
+       char *buf;
+       ssize_t ret;
+       bool nonblock;
+       /* Userspace could be out to fool us */
+       if (!count)
+               return 0;
+       port = filp->private_data;
+       nonblock = filp->f_flags & O_NONBLOCK;
+       if (will_write_block(port)) {
+               if (nonblock)
+                       return -EAGAIN;
+               ret = wait_event_interruptible(port->waitqueue,
+                                              !will_write_block(port));
+               if (ret < 0)
+                       return ret;
+       }
+       /* Port got hot-unplugged. */
+       if (!port->guest_connected)
+               return -ENODEV;
+       count = min((size_t)(32 * 1024), count);
+       buf = kmalloc(count, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+       ret = copy_from_user(buf, ubuf, count);
+       if (ret) {
+               ret = -EFAULT;
+               goto free_buf;
+       }
+       /*
+        * We now ask send_buf() to not spin for generic ports -- we
+        * can re-use the same code path that non-blocking file
+        * descriptors take for blocking file descriptors since the
+        * wait is already done and we're certain the write will go
+        * through to the host.
+        */
+       nonblock = true;
+       ret = send_buf(port, buf, count, nonblock);
+       if (nonblock && ret > 0)
+               goto out;
+ free_buf:
+       kfree(buf);
+ out:
+       return ret;
+ }
+ static unsigned int port_fops_poll(struct file *filp, poll_table *wait)
+ {
+       struct port *port;
+       unsigned int ret;
+       port = filp->private_data;
+       poll_wait(filp, &port->waitqueue, wait);
+       if (!port->guest_connected) {
+               /* Port got unplugged */
+               return POLLHUP;
+       }
+       ret = 0;
+       if (!will_read_block(port))
+               ret |= POLLIN | POLLRDNORM;
+       if (!will_write_block(port))
+               ret |= POLLOUT;
+       if (!port->host_connected)
+               ret |= POLLHUP;
+       return ret;
+ }
+ static void remove_port(struct kref *kref);
+ static int port_fops_release(struct inode *inode, struct file *filp)
+ {
+       struct port *port;
+       port = filp->private_data;
+       /* Notify host of port being closed */
+       send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 0);
+       spin_lock_irq(&port->inbuf_lock);
+       port->guest_connected = false;
+       discard_port_data(port);
+       spin_unlock_irq(&port->inbuf_lock);
+       spin_lock_irq(&port->outvq_lock);
+       reclaim_consumed_buffers(port);
+       spin_unlock_irq(&port->outvq_lock);
+       /*
+        * Locks aren't necessary here as a port can't be opened after
+        * unplug, and if a port isn't unplugged, a kref would already
+        * exist for the port.  Plus, taking ports_lock here would
+        * create a dependency on other locks taken by functions
+        * inside remove_port if we're the last holder of the port,
+        * creating many problems.
+        */
+       kref_put(&port->kref, remove_port);
+       return 0;
+ }
+ static int port_fops_open(struct inode *inode, struct file *filp)
+ {
+       struct cdev *cdev = inode->i_cdev;
+       struct port *port;
+       int ret;
+       port = find_port_by_devt(cdev->dev);
+       filp->private_data = port;
+       /* Prevent against a port getting hot-unplugged at the same time */
+       spin_lock_irq(&port->portdev->ports_lock);
+       kref_get(&port->kref);
+       spin_unlock_irq(&port->portdev->ports_lock);
+       /*
+        * Don't allow opening of console port devices -- that's done
+        * via /dev/hvc
+        */
+       if (is_console_port(port)) {
+               ret = -ENXIO;
+               goto out;
+       }
+       /* Allow only one process to open a particular port at a time */
+       spin_lock_irq(&port->inbuf_lock);
+       if (port->guest_connected) {
+               spin_unlock_irq(&port->inbuf_lock);
+               ret = -EMFILE;
+               goto out;
+       }
+       port->guest_connected = true;
+       spin_unlock_irq(&port->inbuf_lock);
+       spin_lock_irq(&port->outvq_lock);
+       /*
+        * There might be a chance that we missed reclaiming a few
+        * buffers in the window of the port getting previously closed
+        * and opening now.
+        */
+       reclaim_consumed_buffers(port);
+       spin_unlock_irq(&port->outvq_lock);
+       nonseekable_open(inode, filp);
+       /* Notify host of port being opened */
+       send_control_msg(filp->private_data, VIRTIO_CONSOLE_PORT_OPEN, 1);
+       return 0;
+ out:
+       kref_put(&port->kref, remove_port);
+       return ret;
+ }
+ static int port_fops_fasync(int fd, struct file *filp, int mode)
+ {
+       struct port *port;
+       port = filp->private_data;
+       return fasync_helper(fd, filp, mode, &port->async_queue);
+ }
+ /*
+  * The file operations that we support: programs in the guest can open
+  * a console device, read from it, write to it, poll for data and
+  * close it.  The devices are at
+  *   /dev/vport<device number>p<port number>
+  */
+ static const struct file_operations port_fops = {
+       .owner = THIS_MODULE,
+       .open  = port_fops_open,
+       .read  = port_fops_read,
+       .write = port_fops_write,
+       .poll  = port_fops_poll,
+       .release = port_fops_release,
+       .fasync = port_fops_fasync,
+       .llseek = no_llseek,
+ };
+ /*
+  * 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 port *port;
+       if (unlikely(early_put_chars))
+               return early_put_chars(vtermno, buf, count);
+       port = find_port_by_vtermno(vtermno);
+       if (!port)
+               return -EPIPE;
+       return send_buf(port, (void *)buf, count, false);
+ }
+ /*
+  * get_chars() is the callback from the hvc_console infrastructure
+  * when an interrupt is received.
+  *
+  * We call out to fill_readbuf that gets us the required data from the
+  * buffers that are queued up.
+  */
+ static int get_chars(u32 vtermno, char *buf, int count)
+ {
+       struct port *port;
+       /* If we've not set up the port yet, we have no input to give. */
+       if (unlikely(early_put_chars))
+               return 0;
+       port = find_port_by_vtermno(vtermno);
+       if (!port)
+               return -EPIPE;
+       /* If we don't have an input queue yet, we can't get input. */
+       BUG_ON(!port->in_vq);
+       return fill_readbuf(port, buf, count, false);
+ }
+ static void resize_console(struct port *port)
+ {
+       struct virtio_device *vdev;
+       /* The port could have been hot-unplugged */
+       if (!port || !is_console_port(port))
+               return;
+       vdev = port->portdev->vdev;
+       if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_SIZE))
+               hvc_resize(port->cons.hvc, port->cons.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;
+       resize_console(port);
+       return 0;
+ }
+ static void notifier_del_vio(struct hvc_struct *hp, int data)
+ {
+       hp->irq_requested = 0;
+ }
+ /* The operations for console ports. */
+ 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);
+ }
+ int init_port_console(struct port *port)
+ {
+       int ret;
+       /*
+        * The Host's telling us this port is a console port.  Hook it
+        * up with an hvc console.
+        *
+        * To set up and manage our virtual console, we call
+        * hvc_alloc().
+        *
+        * 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->cons.vtermno = pdrvdata.next_vtermno;
+       port->cons.hvc = hvc_alloc(port->cons.vtermno, 0, &hv_ops, PAGE_SIZE);
+       if (IS_ERR(port->cons.hvc)) {
+               ret = PTR_ERR(port->cons.hvc);
+               dev_err(port->dev,
+                       "error %d allocating hvc for port\n", ret);
+               port->cons.hvc = NULL;
+               return ret;
+       }
+       spin_lock_irq(&pdrvdata_lock);
+       pdrvdata.next_vtermno++;
+       list_add_tail(&port->cons.list, &pdrvdata.consoles);
+       spin_unlock_irq(&pdrvdata_lock);
+       port->guest_connected = true;
+       /*
+        * Start using the new console output if this is the first
+        * console to come up.
+        */
+       if (early_put_chars)
+               early_put_chars = NULL;
+       /* Notify host of port being opened */
+       send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 1);
+       return 0;
+ }
+ static ssize_t show_port_name(struct device *dev,
+                             struct device_attribute *attr, char *buffer)
+ {
+       struct port *port;
+       port = dev_get_drvdata(dev);
+       return sprintf(buffer, "%s\n", port->name);
+ }
+ static DEVICE_ATTR(name, S_IRUGO, show_port_name, NULL);
+ static struct attribute *port_sysfs_entries[] = {
+       &dev_attr_name.attr,
+       NULL
+ };
+ static struct attribute_group port_attribute_group = {
+       .name = NULL,           /* put in device directory */
+       .attrs = port_sysfs_entries,
+ };
+ static int debugfs_open(struct inode *inode, struct file *filp)
+ {
+       filp->private_data = inode->i_private;
+       return 0;
+ }
+ static ssize_t debugfs_read(struct file *filp, char __user *ubuf,
+                           size_t count, loff_t *offp)
+ {
+       struct port *port;
+       char *buf;
+       ssize_t ret, out_offset, out_count;
+       out_count = 1024;
+       buf = kmalloc(out_count, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+       port = filp->private_data;
+       out_offset = 0;
+       out_offset += snprintf(buf + out_offset, out_count,
+                              "name: %s\n", port->name ? port->name : "");
+       out_offset += snprintf(buf + out_offset, out_count - out_offset,
+                              "guest_connected: %d\n", port->guest_connected);
+       out_offset += snprintf(buf + out_offset, out_count - out_offset,
+                              "host_connected: %d\n", port->host_connected);
+       out_offset += snprintf(buf + out_offset, out_count - out_offset,
+                              "outvq_full: %d\n", port->outvq_full);
+       out_offset += snprintf(buf + out_offset, out_count - out_offset,
+                              "is_console: %s\n",
+                              is_console_port(port) ? "yes" : "no");
+       out_offset += snprintf(buf + out_offset, out_count - out_offset,
+                              "console_vtermno: %u\n", port->cons.vtermno);
+       ret = simple_read_from_buffer(ubuf, count, offp, buf, out_offset);
+       kfree(buf);
+       return ret;
+ }
+ static const struct file_operations port_debugfs_ops = {
+       .owner = THIS_MODULE,
+       .open  = debugfs_open,
+       .read  = debugfs_read,
+ };
+ static void set_console_size(struct port *port, u16 rows, u16 cols)
+ {
+       if (!port || !is_console_port(port))
+               return;
+       port->cons.ws.ws_row = rows;
+       port->cons.ws.ws_col = cols;
+ }
+ static unsigned int fill_queue(struct virtqueue *vq, spinlock_t *lock)
+ {
+       struct port_buffer *buf;
+       unsigned int nr_added_bufs;
+       int ret;
+       nr_added_bufs = 0;
+       do {
+               buf = alloc_buf(PAGE_SIZE);
+               if (!buf)
+                       break;
+               spin_lock_irq(lock);
+               ret = add_inbuf(vq, buf);
+               if (ret < 0) {
+                       spin_unlock_irq(lock);
+                       free_buf(buf);
+                       break;
+               }
+               nr_added_bufs++;
+               spin_unlock_irq(lock);
+       } while (ret > 0);
+       return nr_added_bufs;
+ }
+ static void send_sigio_to_port(struct port *port)
+ {
+       if (port->async_queue && port->guest_connected)
+               kill_fasync(&port->async_queue, SIGIO, POLL_OUT);
+ }
+ static int add_port(struct ports_device *portdev, u32 id)
+ {
+       char debugfs_name[16];
+       struct port *port;
+       struct port_buffer *buf;
+       dev_t devt;
+       unsigned int nr_added_bufs;
+       int err;
+       port = kmalloc(sizeof(*port), GFP_KERNEL);
+       if (!port) {
+               err = -ENOMEM;
+               goto fail;
+       }
+       kref_init(&port->kref);
+       port->portdev = portdev;
+       port->id = id;
+       port->name = NULL;
+       port->inbuf = NULL;
+       port->cons.hvc = NULL;
+       port->async_queue = NULL;
+       port->cons.ws.ws_row = port->cons.ws.ws_col = 0;
+       port->host_connected = port->guest_connected = false;
+       port->outvq_full = false;
+       port->in_vq = portdev->in_vqs[port->id];
+       port->out_vq = portdev->out_vqs[port->id];
+       port->cdev = cdev_alloc();
+       if (!port->cdev) {
+               dev_err(&port->portdev->vdev->dev, "Error allocating cdev\n");
+               err = -ENOMEM;
+               goto free_port;
+       }
+       port->cdev->ops = &port_fops;
+       devt = MKDEV(portdev->chr_major, id);
+       err = cdev_add(port->cdev, devt, 1);
+       if (err < 0) {
+               dev_err(&port->portdev->vdev->dev,
+                       "Error %d adding cdev for port %u\n", err, id);
+               goto free_cdev;
+       }
+       port->dev = device_create(pdrvdata.class, &port->portdev->vdev->dev,
+                                 devt, port, "vport%up%u",
+                                 port->portdev->drv_index, id);
+       if (IS_ERR(port->dev)) {
+               err = PTR_ERR(port->dev);
+               dev_err(&port->portdev->vdev->dev,
+                       "Error %d creating device for port %u\n",
+                       err, id);
+               goto free_cdev;
+       }
+       spin_lock_init(&port->inbuf_lock);
+       spin_lock_init(&port->outvq_lock);
+       init_waitqueue_head(&port->waitqueue);
+       /* Fill the in_vq with buffers so the host can send us data. */
+       nr_added_bufs = fill_queue(port->in_vq, &port->inbuf_lock);
+       if (!nr_added_bufs) {
+               dev_err(port->dev, "Error allocating inbufs\n");
+               err = -ENOMEM;
+               goto free_device;
+       }
+       /*
+        * If we're not using multiport support, this has to be a console port
+        */
+       if (!use_multiport(port->portdev)) {
+               err = init_port_console(port);
+               if (err)
+                       goto free_inbufs;
+       }
+       spin_lock_irq(&portdev->ports_lock);
+       list_add_tail(&port->list, &port->portdev->ports);
+       spin_unlock_irq(&portdev->ports_lock);
+       /*
+        * Tell the Host we're set so that it can send us various
+        * configuration parameters for this port (eg, port name,
+        * caching, whether this is a console port, etc.)
+        */
+       send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
+       if (pdrvdata.debugfs_dir) {
+               /*
+                * Finally, create the debugfs file that we can use to
+                * inspect a port's state at any time
+                */
+               sprintf(debugfs_name, "vport%up%u",
+                       port->portdev->drv_index, id);
+               port->debugfs_file = debugfs_create_file(debugfs_name, 0444,
+                                                        pdrvdata.debugfs_dir,
+                                                        port,
+                                                        &port_debugfs_ops);
+       }
+       return 0;
+ free_inbufs:
+       while ((buf = virtqueue_detach_unused_buf(port->in_vq)))
+               free_buf(buf);
+ free_device:
+       device_destroy(pdrvdata.class, port->dev->devt);
+ free_cdev:
+       cdev_del(port->cdev);
+ free_port:
+       kfree(port);
+ fail:
+       /* The host might want to notify management sw about port add failure */
+       __send_control_msg(portdev, id, VIRTIO_CONSOLE_PORT_READY, 0);
+       return err;
+ }
+ /* No users remain, remove all port-specific data. */
+ static void remove_port(struct kref *kref)
+ {
+       struct port *port;
+       port = container_of(kref, struct port, kref);
+       sysfs_remove_group(&port->dev->kobj, &port_attribute_group);
+       device_destroy(pdrvdata.class, port->dev->devt);
+       cdev_del(port->cdev);
+       kfree(port->name);
+       debugfs_remove(port->debugfs_file);
+       kfree(port);
+ }
+ /*
+  * Port got unplugged.  Remove port from portdev's list and drop the
+  * kref reference.  If no userspace has this port opened, it will
+  * result in immediate removal the port.
+  */
+ static void unplug_port(struct port *port)
+ {
+       struct port_buffer *buf;
+       spin_lock_irq(&port->portdev->ports_lock);
+       list_del(&port->list);
+       spin_unlock_irq(&port->portdev->ports_lock);
+       if (port->guest_connected) {
+               port->guest_connected = false;
+               port->host_connected = false;
+               wake_up_interruptible(&port->waitqueue);
+               /* Let the app know the port is going down. */
+               send_sigio_to_port(port);
+       }
+       if (is_console_port(port)) {
+               spin_lock_irq(&pdrvdata_lock);
+               list_del(&port->cons.list);
+               spin_unlock_irq(&pdrvdata_lock);
+ #if 0
+               /*
+                * hvc_remove() not called as removing one hvc port
+                * results in other hvc ports getting frozen.
+                *
+                * Once this is resolved in hvc, this functionality
+                * will be enabled.  Till that is done, the -EPIPE
+                * return from get_chars() above will help
+                * hvc_console.c to clean up on ports we remove here.
+                */
+               hvc_remove(port->cons.hvc);
+ #endif
+       }
+       /* Remove unused data this port might have received. */
+       discard_port_data(port);
+       reclaim_consumed_buffers(port);
+       /* Remove buffers we queued up for the Host to send us data in. */
+       while ((buf = virtqueue_detach_unused_buf(port->in_vq)))
+               free_buf(buf);
+       /*
+        * We should just assume the device itself has gone off --
+        * else a close on an open port later will try to send out a
+        * control message.
+        */
+       port->portdev = NULL;
+       /*
+        * Locks around here are not necessary - a port can't be
+        * opened after we removed the port struct from ports_list
+        * above.
+        */
+       kref_put(&port->kref, remove_port);
+ }
+ /* Any private messages that the Host and Guest want to share */
+ static void handle_control_message(struct ports_device *portdev,
+                                  struct port_buffer *buf)
+ {
+       struct virtio_console_control *cpkt;
+       struct port *port;
+       size_t name_size;
+       int err;
+       cpkt = (struct virtio_console_control *)(buf->buf + buf->offset);
+       port = find_port_by_id(portdev, cpkt->id);
+       if (!port && cpkt->event != VIRTIO_CONSOLE_PORT_ADD) {
+               /* No valid header at start of buffer.  Drop it. */
+               dev_dbg(&portdev->vdev->dev,
+                       "Invalid index %u in control packet\n", cpkt->id);
+               return;
+       }
+       switch (cpkt->event) {
+       case VIRTIO_CONSOLE_PORT_ADD:
+               if (port) {
+                       dev_dbg(&portdev->vdev->dev,
+                               "Port %u already added\n", port->id);
+                       send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
+                       break;
+               }
+               if (cpkt->id >= portdev->config.max_nr_ports) {
+                       dev_warn(&portdev->vdev->dev,
+                               "Request for adding port with out-of-bound id %u, max. supported id: %u\n",
+                               cpkt->id, portdev->config.max_nr_ports - 1);
+                       break;
+               }
+               add_port(portdev, cpkt->id);
+               break;
+       case VIRTIO_CONSOLE_PORT_REMOVE:
+               unplug_port(port);
+               break;
+       case VIRTIO_CONSOLE_CONSOLE_PORT:
+               if (!cpkt->value)
+                       break;
+               if (is_console_port(port))
+                       break;
+               init_port_console(port);
+               /*
+                * Could remove the port here in case init fails - but
+                * have to notify the host first.
+                */
+               break;
+       case VIRTIO_CONSOLE_RESIZE: {
+               struct {
+                       __u16 rows;
+                       __u16 cols;
+               } size;
+               if (!is_console_port(port))
+                       break;
+               memcpy(&size, buf->buf + buf->offset + sizeof(*cpkt),
+                      sizeof(size));
+               set_console_size(port, size.rows, size.cols);
+               port->cons.hvc->irq_requested = 1;
+               resize_console(port);
+               break;
+       }
+       case VIRTIO_CONSOLE_PORT_OPEN:
+               port->host_connected = cpkt->value;
+               wake_up_interruptible(&port->waitqueue);
+               /*
+                * If the host port got closed and the host had any
+                * unconsumed buffers, we'll be able to reclaim them
+                * now.
+                */
+               spin_lock_irq(&port->outvq_lock);
+               reclaim_consumed_buffers(port);
+               spin_unlock_irq(&port->outvq_lock);
+               /*
+                * If the guest is connected, it'll be interested in
+                * knowing the host connection state changed.
+                */
+               send_sigio_to_port(port);
+               break;
+       case VIRTIO_CONSOLE_PORT_NAME:
+               /*
+                * Skip the size of the header and the cpkt to get the size
+                * of the name that was sent
+                */
+               name_size = buf->len - buf->offset - sizeof(*cpkt) + 1;
+               port->name = kmalloc(name_size, GFP_KERNEL);
+               if (!port->name) {
+                       dev_err(port->dev,
+                               "Not enough space to store port name\n");
+                       break;
+               }
+               strncpy(port->name, buf->buf + buf->offset + sizeof(*cpkt),
+                       name_size - 1);
+               port->name[name_size - 1] = 0;
+               /*
+                * Since we only have one sysfs attribute, 'name',
+                * create it only if we have a name for the port.
+                */
+               err = sysfs_create_group(&port->dev->kobj,
+                                        &port_attribute_group);
+               if (err) {
+                       dev_err(port->dev,
+                               "Error %d creating sysfs device attributes\n",
+                               err);
+               } else {
+                       /*
+                        * Generate a udev event so that appropriate
+                        * symlinks can be created based on udev
+                        * rules.
+                        */
+                       kobject_uevent(&port->dev->kobj, KOBJ_CHANGE);
+               }
+               break;
+       }
+ }
+ static void control_work_handler(struct work_struct *work)
+ {
+       struct ports_device *portdev;
+       struct virtqueue *vq;
+       struct port_buffer *buf;
+       unsigned int len;
+       portdev = container_of(work, struct ports_device, control_work);
+       vq = portdev->c_ivq;
+       spin_lock(&portdev->cvq_lock);
+       while ((buf = virtqueue_get_buf(vq, &len))) {
+               spin_unlock(&portdev->cvq_lock);
+               buf->len = len;
+               buf->offset = 0;
+               handle_control_message(portdev, buf);
+               spin_lock(&portdev->cvq_lock);
+               if (add_inbuf(portdev->c_ivq, buf) < 0) {
+                       dev_warn(&portdev->vdev->dev,
+                                "Error adding buffer to queue\n");
+                       free_buf(buf);
+               }
+       }
+       spin_unlock(&portdev->cvq_lock);
+ }
++static void out_intr(struct virtqueue *vq)
++{
++      struct port *port;
++
++      port = find_port_by_vq(vq->vdev->priv, vq);
++      if (!port)
++              return;
++
++      wake_up_interruptible(&port->waitqueue);
++}
++
+ static void in_intr(struct virtqueue *vq)
+ {
+       struct port *port;
+       unsigned long flags;
+       port = find_port_by_vq(vq->vdev->priv, vq);
+       if (!port)
+               return;
+       spin_lock_irqsave(&port->inbuf_lock, flags);
+       if (!port->inbuf)
+               port->inbuf = get_inbuf(port);
+       /*
+        * Don't queue up data when port is closed.  This condition
+        * can be reached when a console port is not yet connected (no
+        * tty is spawned) and the host sends out data to console
+        * ports.  For generic serial ports, the host won't
+        * (shouldn't) send data till the guest is connected.
+        */
+       if (!port->guest_connected)
+               discard_port_data(port);
+       spin_unlock_irqrestore(&port->inbuf_lock, flags);
+       wake_up_interruptible(&port->waitqueue);
+       /* Send a SIGIO indicating new data in case the process asked for it */
+       send_sigio_to_port(port);
+       if (is_console_port(port) && hvc_poll(port->cons.hvc))
+               hvc_kick();
+ }
+ static void control_intr(struct virtqueue *vq)
+ {
+       struct ports_device *portdev;
+       portdev = vq->vdev->priv;
+       schedule_work(&portdev->control_work);
+ }
+ static void config_intr(struct virtio_device *vdev)
+ {
+       struct ports_device *portdev;
+       portdev = vdev->priv;
+       if (!use_multiport(portdev)) {
+               struct port *port;
+               u16 rows, cols;
+               vdev->config->get(vdev,
+                                 offsetof(struct virtio_console_config, cols),
+                                 &cols, sizeof(u16));
+               vdev->config->get(vdev,
+                                 offsetof(struct virtio_console_config, rows),
+                                 &rows, sizeof(u16));
+               port = find_port_by_id(portdev, 0);
+               set_console_size(port, rows, cols);
+               /*
+                * We'll use this way of resizing only for legacy
+                * support.  For newer userspace
+                * (VIRTIO_CONSOLE_F_MULTPORT+), use control messages
+                * to indicate console size changes so that it can be
+                * done per-port.
+                */
+               resize_console(port);
+       }
+ }
+ static int init_vqs(struct ports_device *portdev)
+ {
+       vq_callback_t **io_callbacks;
+       char **io_names;
+       struct virtqueue **vqs;
+       u32 i, j, nr_ports, nr_queues;
+       int err;
+       nr_ports = portdev->config.max_nr_ports;
+       nr_queues = use_multiport(portdev) ? (nr_ports + 1) * 2 : 2;
+       vqs = kmalloc(nr_queues * sizeof(struct virtqueue *), GFP_KERNEL);
+       io_callbacks = kmalloc(nr_queues * sizeof(vq_callback_t *), GFP_KERNEL);
+       io_names = kmalloc(nr_queues * sizeof(char *), GFP_KERNEL);
+       portdev->in_vqs = kmalloc(nr_ports * sizeof(struct virtqueue *),
+                                 GFP_KERNEL);
+       portdev->out_vqs = kmalloc(nr_ports * sizeof(struct virtqueue *),
+                                  GFP_KERNEL);
+       if (!vqs || !io_callbacks || !io_names || !portdev->in_vqs ||
+                       !portdev->out_vqs) {
+               err = -ENOMEM;
+               goto free;
+       }
+       /*
+        * For backward compat (newer host but older guest), the host
+        * spawns a console port first and also inits the vqs for port
+        * 0 before others.
+        */
+       j = 0;
+       io_callbacks[j] = in_intr;
 -                      io_callbacks[j + 1] = NULL;
++      io_callbacks[j + 1] = out_intr;
+       io_names[j] = "input";
+       io_names[j + 1] = "output";
+       j += 2;
+       if (use_multiport(portdev)) {
+               io_callbacks[j] = control_intr;
+               io_callbacks[j + 1] = NULL;
+               io_names[j] = "control-i";
+               io_names[j + 1] = "control-o";
+               for (i = 1; i < nr_ports; i++) {
+                       j += 2;
+                       io_callbacks[j] = in_intr;
++                      io_callbacks[j + 1] = out_intr;
+                       io_names[j] = "input";
+                       io_names[j + 1] = "output";
+               }
+       }
+       /* Find the queues. */
+       err = portdev->vdev->config->find_vqs(portdev->vdev, nr_queues, vqs,
+                                             io_callbacks,
+                                             (const char **)io_names);
+       if (err)
+               goto free;
+       j = 0;
+       portdev->in_vqs[0] = vqs[0];
+       portdev->out_vqs[0] = vqs[1];
+       j += 2;
+       if (use_multiport(portdev)) {
+               portdev->c_ivq = vqs[j];
+               portdev->c_ovq = vqs[j + 1];
+               for (i = 1; i < nr_ports; i++) {
+                       j += 2;
+                       portdev->in_vqs[i] = vqs[j];
+                       portdev->out_vqs[i] = vqs[j + 1];
+               }
+       }
+       kfree(io_names);
+       kfree(io_callbacks);
+       kfree(vqs);
+       return 0;
+ free:
+       kfree(portdev->out_vqs);
+       kfree(portdev->in_vqs);
+       kfree(io_names);
+       kfree(io_callbacks);
+       kfree(vqs);
+       return err;
+ }
+ static const struct file_operations portdev_fops = {
+       .owner = THIS_MODULE,
+ };
+ /*
+  * Once we're further in boot, we get probed like any other virtio
+  * device.
+  *
+  * If the host also supports multiple console ports, we check the
+  * config space to see how many ports the host has spawned.  We
+  * initialize each port found.
+  */
+ static int __devinit virtcons_probe(struct virtio_device *vdev)
+ {
+       struct ports_device *portdev;
+       int err;
+       bool multiport;
+       portdev = kmalloc(sizeof(*portdev), GFP_KERNEL);
+       if (!portdev) {
+               err = -ENOMEM;
+               goto fail;
+       }
+       /* Attach this portdev to this virtio_device, and vice-versa. */
+       portdev->vdev = vdev;
+       vdev->priv = portdev;
+       spin_lock_irq(&pdrvdata_lock);
+       portdev->drv_index = pdrvdata.index++;
+       spin_unlock_irq(&pdrvdata_lock);
+       portdev->chr_major = register_chrdev(0, "virtio-portsdev",
+                                            &portdev_fops);
+       if (portdev->chr_major < 0) {
+               dev_err(&vdev->dev,
+                       "Error %d registering chrdev for device %u\n",
+                       portdev->chr_major, portdev->drv_index);
+               err = portdev->chr_major;
+               goto free;
+       }
+       multiport = false;
+       portdev->config.max_nr_ports = 1;
+       if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT)) {
+               multiport = true;
+               vdev->features[0] |= 1 << VIRTIO_CONSOLE_F_MULTIPORT;
+               vdev->config->get(vdev, offsetof(struct virtio_console_config,
+                                                max_nr_ports),
+                                 &portdev->config.max_nr_ports,
+                                 sizeof(portdev->config.max_nr_ports));
+       }
+       /* Let the Host know we support multiple ports.*/
+       vdev->config->finalize_features(vdev);
+       err = init_vqs(portdev);
+       if (err < 0) {
+               dev_err(&vdev->dev, "Error %d initializing vqs\n", err);
+               goto free_chrdev;
+       }
+       spin_lock_init(&portdev->ports_lock);
+       INIT_LIST_HEAD(&portdev->ports);
+       if (multiport) {
+               unsigned int nr_added_bufs;
+               spin_lock_init(&portdev->cvq_lock);
+               INIT_WORK(&portdev->control_work, &control_work_handler);
+               nr_added_bufs = fill_queue(portdev->c_ivq, &portdev->cvq_lock);
+               if (!nr_added_bufs) {
+                       dev_err(&vdev->dev,
+                               "Error allocating buffers for control queue\n");
+                       err = -ENOMEM;
+                       goto free_vqs;
+               }
+       } else {
+               /*
+                * For backward compatibility: Create a console port
+                * if we're running on older host.
+                */
+               add_port(portdev, 0);
+       }
+       spin_lock_irq(&pdrvdata_lock);
+       list_add_tail(&portdev->list, &pdrvdata.portdevs);
+       spin_unlock_irq(&pdrvdata_lock);
+       __send_control_msg(portdev, VIRTIO_CONSOLE_BAD_ID,
+                          VIRTIO_CONSOLE_DEVICE_READY, 1);
+       return 0;
+ free_vqs:
+       /* The host might want to notify mgmt sw about device add failure */
+       __send_control_msg(portdev, VIRTIO_CONSOLE_BAD_ID,
+                          VIRTIO_CONSOLE_DEVICE_READY, 0);
+       vdev->config->del_vqs(vdev);
+       kfree(portdev->in_vqs);
+       kfree(portdev->out_vqs);
+ free_chrdev:
+       unregister_chrdev(portdev->chr_major, "virtio-portsdev");
+ free:
+       kfree(portdev);
+ fail:
+       return err;
+ }
+ static void virtcons_remove(struct virtio_device *vdev)
+ {
+       struct ports_device *portdev;
+       struct port *port, *port2;
+       portdev = vdev->priv;
+       spin_lock_irq(&pdrvdata_lock);
+       list_del(&portdev->list);
+       spin_unlock_irq(&pdrvdata_lock);
+       /* Disable interrupts for vqs */
+       vdev->config->reset(vdev);
+       /* Finish up work that's lined up */
+       cancel_work_sync(&portdev->control_work);
+       list_for_each_entry_safe(port, port2, &portdev->ports, list)
+               unplug_port(port);
+       unregister_chrdev(portdev->chr_major, "virtio-portsdev");
+       /*
+        * When yanking out a device, we immediately lose the
+        * (device-side) queues.  So there's no point in keeping the
+        * guest side around till we drop our final reference.  This
+        * also means that any ports which are in an open state will
+        * have to just stop using the port, as the vqs are going
+        * away.
+        */
+       if (use_multiport(portdev)) {
+               struct port_buffer *buf;
+               unsigned int len;
+               while ((buf = virtqueue_get_buf(portdev->c_ivq, &len)))
+                       free_buf(buf);
+               while ((buf = virtqueue_detach_unused_buf(portdev->c_ivq)))
+                       free_buf(buf);
+       }
+       vdev->config->del_vqs(vdev);
+       kfree(portdev->in_vqs);
+       kfree(portdev->out_vqs);
+       kfree(portdev);
+ }
+ static struct virtio_device_id id_table[] = {
+       { VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID },
+       { 0 },
+ };
+ static unsigned int features[] = {
+       VIRTIO_CONSOLE_F_SIZE,
+       VIRTIO_CONSOLE_F_MULTIPORT,
+ };
+ 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,
+       .remove =       virtcons_remove,
+       .config_changed = config_intr,
+ };
+ static int __init init(void)
+ {
+       int err;
+       pdrvdata.class = class_create(THIS_MODULE, "virtio-ports");
+       if (IS_ERR(pdrvdata.class)) {
+               err = PTR_ERR(pdrvdata.class);
+               pr_err("Error %d creating virtio-ports class\n", err);
+               return err;
+       }
+       pdrvdata.debugfs_dir = debugfs_create_dir("virtio-ports", NULL);
+       if (!pdrvdata.debugfs_dir) {
+               pr_warning("Error %ld creating debugfs dir for virtio-ports\n",
+                          PTR_ERR(pdrvdata.debugfs_dir));
+       }
+       INIT_LIST_HEAD(&pdrvdata.consoles);
+       INIT_LIST_HEAD(&pdrvdata.portdevs);
+       return register_virtio_driver(&virtio_console);
+ }
+ static void __exit fini(void)
+ {
+       unregister_virtio_driver(&virtio_console);
+       class_destroy(pdrvdata.class);
+       if (pdrvdata.debugfs_dir)
+               debugfs_remove_recursive(pdrvdata.debugfs_dir);
+ }
+ module_init(init);
+ module_exit(fini);
+ MODULE_DEVICE_TABLE(virtio, id_table);
+ MODULE_DESCRIPTION("Virtio console driver");
+ MODULE_LICENSE("GPL");