tty: move hvc drivers to drivers/tty/hvc/

As requested by Arnd Bergmann, the hvc drivers are now
moved to the drivers/tty/hvc/ directory.  The virtio_console.c driver
was also moved, as it required the hvc_console.h file to be able to be
built, and it really is a hvc driver.

Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 0 insertions, 1604 deletions

diff --git a/drivers/char/hvcs.c b/drivers/char/hvcs.c
deleted file mode 100644
index bedc6c1b6fa5..000000000000
--- a/drivers/char/hvcs.c
+++ /dev/null
@@ -1,1604 +0,0 @@
-/*
- * IBM eServer Hypervisor Virtual Console Server Device Driver
- * Copyright (C) 2003, 2004 IBM Corp.
- *  Ryan S. Arnold (rsa@us.ibm.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
- *
- * Author(s) :  Ryan S. Arnold <rsa@us.ibm.com>
- *
- * This is the device driver for the IBM Hypervisor Virtual Console Server,
- * "hvcs".  The IBM hvcs provides a tty driver interface to allow Linux
- * user space applications access to the system consoles of logically
- * partitioned operating systems, e.g. Linux, running on the same partitioned
- * Power5 ppc64 system.  Physical hardware consoles per partition are not
- * practical on this hardware so system consoles are accessed by this driver
- * using inter-partition firmware interfaces to virtual terminal devices.
- *
- * A vty is known to the HMC as a "virtual serial server adapter".  It is a
- * virtual terminal device that is created by firmware upon partition creation
- * to act as a partitioned OS's console device.
- *
- * Firmware dynamically (via hotplug) exposes vty-servers to a running ppc64
- * Linux system upon their creation by the HMC or their exposure during boot.
- * The non-user interactive backend of this driver is implemented as a vio
- * device driver so that it can receive notification of vty-server lifetimes
- * after it registers with the vio bus to handle vty-server probe and remove
- * callbacks.
- *
- * Many vty-servers can be configured to connect to one vty, but a vty can
- * only be actively connected to by a single vty-server, in any manner, at one
- * time.  If the HMC is currently hosting the console for a target Linux
- * partition; attempts to open the tty device to the partition's console using
- * the hvcs on any partition will return -EBUSY with every open attempt until
- * the HMC frees the connection between its vty-server and the desired
- * partition's vty device.  Conversely, a vty-server may only be connected to
- * a single vty at one time even though it may have several configured vty
- * partner possibilities.
- *
- * Firmware does not provide notification of vty partner changes to this
- * driver.  This means that an HMC Super Admin may add or remove partner vtys
- * from a vty-server's partner list but the changes will not be signaled to
- * the vty-server.  Firmware only notifies the driver when a vty-server is
- * added or removed from the system.  To compensate for this deficiency, this
- * driver implements a sysfs update attribute which provides a method for
- * rescanning partner information upon a user's request.
- *
- * Each vty-server, prior to being exposed to this driver is reference counted
- * using the 2.6 Linux kernel kref construct.
- *
- * For direction on installation and usage of this driver please reference
- * Documentation/powerpc/hvcs.txt.
- */
-
-#include <linux/device.h>
-#include <linux/init.h>
-#include <linux/interrupt.h>
-#include <linux/kernel.h>
-#include <linux/kref.h>
-#include <linux/kthread.h>
-#include <linux/list.h>
-#include <linux/major.h>
-#include <linux/module.h>
-#include <linux/moduleparam.h>
-#include <linux/sched.h>
-#include <linux/slab.h>
-#include <linux/spinlock.h>
-#include <linux/stat.h>
-#include <linux/tty.h>
-#include <linux/tty_flip.h>
-#include <asm/hvconsole.h>
-#include <asm/hvcserver.h>
-#include <asm/uaccess.h>
-#include <asm/vio.h>
-
-/*
- * 1.3.0 -> 1.3.1 In hvcs_open memset(..,0x00,..) instead of memset(..,0x3F,00).
- * Removed braces around single statements following conditionals.  Removed '=
- * 0' after static int declarations since these default to zero.  Removed
- * list_for_each_safe() and replaced with list_for_each_entry() in
- * hvcs_get_by_index().  The 'safe' version is un-needed now that the driver is
- * using spinlocks.  Changed spin_lock_irqsave() to spin_lock() when locking
- * hvcs_structs_lock and hvcs_pi_lock since these are not touched in an int
- * handler.  Initialized hvcs_structs_lock and hvcs_pi_lock to
- * SPIN_LOCK_UNLOCKED at declaration time rather than in hvcs_module_init().
- * Added spin_lock around list_del() in destroy_hvcs_struct() to protect the
- * list traversals from a deletion.  Removed '= NULL' from pointer declaration
- * statements since they are initialized NULL by default.  Removed wmb()
- * instances from hvcs_try_write().  They probably aren't needed with locking in
- * place.  Added check and cleanup for hvcs_pi_buff = kmalloc() in
- * hvcs_module_init().  Exposed hvcs_struct.index via a sysfs attribute so that
- * the coupling between /dev/hvcs* and a vty-server can be automatically
- * determined.  Moved kobject_put() in hvcs_open outside of the
- * spin_unlock_irqrestore().
- *
- * 1.3.1 -> 1.3.2 Changed method for determining hvcs_struct->index and had it
- * align with how the tty layer always assigns the lowest index available.  This
- * change resulted in a list of ints that denotes which indexes are available.
- * Device additions and removals use the new hvcs_get_index() and
- * hvcs_return_index() helper functions.  The list is created with
- * hvsc_alloc_index_list() and it is destroyed with hvcs_free_index_list().
- * Without these fixes hotplug vty-server adapter support goes crazy with this
- * driver if the user removes a vty-server adapter.  Moved free_irq() outside of
- * the hvcs_final_close() function in order to get it out of the spinlock.
- * Rearranged hvcs_close().  Cleaned up some printks and did some housekeeping
- * on the changelog.  Removed local CLC_LENGTH and used HVCS_CLC_LENGTH from
- * arch/powerepc/include/asm/hvcserver.h
- *
- * 1.3.2 -> 1.3.3 Replaced yield() in hvcs_close() with tty_wait_until_sent() to
- * prevent possible lockup with realtime scheduling as similarily pointed out by
- * akpm in hvc_console.  Changed resulted in the removal of hvcs_final_close()
- * to reorder cleanup operations and prevent discarding of pending data during
- * an hvcs_close().  Removed spinlock protection of hvcs_struct data members in
- * hvcs_write_room() and hvcs_chars_in_buffer() because they aren't needed.
- */
-
-#define HVCS_DRIVER_VERSION "1.3.3"
-
-MODULE_AUTHOR("Ryan S. Arnold <rsa@us.ibm.com>");
-MODULE_DESCRIPTION("IBM hvcs (Hypervisor Virtual Console Server) Driver");
-MODULE_LICENSE("GPL");
-MODULE_VERSION(HVCS_DRIVER_VERSION);
-
-/*
- * Wait this long per iteration while trying to push buffered data to the
- * hypervisor before allowing the tty to complete a close operation.
- */
-#define HVCS_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
-
-/*
- * Since the Linux TTY code does not currently (2-04-2004) support dynamic
- * addition of tty derived devices and we shouldn't allocate thousands of
- * tty_device pointers when the number of vty-server & vty partner connections
- * will most often be much lower than this, we'll arbitrarily allocate
- * HVCS_DEFAULT_SERVER_ADAPTERS tty_structs and cdev's by default when we
- * register the tty_driver. This can be overridden using an insmod parameter.
- */
-#define HVCS_DEFAULT_SERVER_ADAPTERS	64
-
-/*
- * The user can't insmod with more than HVCS_MAX_SERVER_ADAPTERS hvcs device
- * nodes as a sanity check.  Theoretically there can be over 1 Billion
- * vty-server & vty partner connections.
- */
-#define HVCS_MAX_SERVER_ADAPTERS	1024
-
-/*
- * We let Linux assign us a major number and we start the minors at zero.  There
- * is no intuitive mapping between minor number and the target vty-server
- * adapter except that each new vty-server adapter is always assigned to the
- * smallest minor number available.
- */
-#define HVCS_MINOR_START	0
-
-/*
- * The hcall interface involves putting 8 chars into each of two registers.
- * We load up those 2 registers (in arch/powerpc/platforms/pseries/hvconsole.c)
- * by casting char[16] to long[2].  It would work without __ALIGNED__, but a 
- * little (tiny) bit slower because an unaligned load is slower than aligned 
- * load.
- */
-#define __ALIGNED__	__attribute__((__aligned__(8)))
-
-/*
- * How much data can firmware send with each hvc_put_chars()?  Maybe this
- * should be moved into an architecture specific area.
- */
-#define HVCS_BUFF_LEN	16
-
-/*
- * This is the maximum amount of data we'll let the user send us (hvcs_write) at
- * once in a chunk as a sanity check.
- */
-#define HVCS_MAX_FROM_USER	4096
-
-/*
- * Be careful when adding flags to this line discipline.  Don't add anything
- * that will cause echoing or we'll go into recursive loop echoing chars back
- * and forth with the console drivers.
- */
-static struct ktermios hvcs_tty_termios = {
-	.c_iflag = IGNBRK | IGNPAR,
-	.c_oflag = OPOST,
-	.c_cflag = B38400 | CS8 | CREAD | HUPCL,
-	.c_cc = INIT_C_CC,
-	.c_ispeed = 38400,
-	.c_ospeed = 38400
-};
-
-/*
- * This value is used to take the place of a command line parameter when the
- * module is inserted.  It starts as -1 and stays as such if the user doesn't
- * specify a module insmod parameter.  If they DO specify one then it is set to
- * the value of the integer passed in.
- */
-static int hvcs_parm_num_devs = -1;
-module_param(hvcs_parm_num_devs, int, 0);
-
-static const char hvcs_driver_name[] = "hvcs";
-static const char hvcs_device_node[] = "hvcs";
-static const char hvcs_driver_string[]
-	= "IBM hvcs (Hypervisor Virtual Console Server) Driver";
-
-/* Status of partner info rescan triggered via sysfs. */
-static int hvcs_rescan_status;
-
-static struct tty_driver *hvcs_tty_driver;
-
-/*
- * In order to be somewhat sane this driver always associates the hvcs_struct
- * index element with the numerically equal tty->index.  This means that a
- * hotplugged vty-server adapter will always map to the lowest index valued
- * device node.  If vty-servers were hotplug removed from the system and then
- * new ones added the new vty-server may have the largest slot number of all
- * the vty-server adapters in the partition but it may have the lowest dev node
- * index of all the adapters due to the hole left by the hotplug removed
- * adapter.  There are a set of functions provided to get the lowest index for
- * a new device as well as return the index to the list.  This list is allocated
- * with a number of elements equal to the number of device nodes requested when
- * the module was inserted.
- */
-static int *hvcs_index_list;
-
-/*
- * How large is the list?  This is kept for traversal since the list is
- * dynamically created.
- */
-static int hvcs_index_count;
-
-/*
- * Used by the khvcsd to pick up I/O operations when the kernel_thread is
- * already awake but potentially shifted to TASK_INTERRUPTIBLE state.
- */
-static int hvcs_kicked;
-
-/*
- * Use by the kthread construct for task operations like waking the sleeping
- * thread and stopping the kthread.
- */
-static struct task_struct *hvcs_task;
-
-/*
- * We allocate this for the use of all of the hvcs_structs when they fetch
- * partner info.
- */
-static unsigned long *hvcs_pi_buff;
-
-/* Only allow one hvcs_struct to use the hvcs_pi_buff at a time. */
-static DEFINE_SPINLOCK(hvcs_pi_lock);
-
-/* One vty-server per hvcs_struct */
-struct hvcs_struct {
-	spinlock_t lock;
-
-	/*
-	 * This index identifies this hvcs device as the complement to a
-	 * specific tty index.
-	 */
-	unsigned int index;
-
-	struct tty_struct *tty;
-	int open_count;
-
-	/*
-	 * Used to tell the driver kernel_thread what operations need to take
-	 * place upon this hvcs_struct instance.
-	 */
-	int todo_mask;
-
-	/*
-	 * This buffer is required so that when hvcs_write_room() reports that
-	 * it can send HVCS_BUFF_LEN characters that it will buffer the full
-	 * HVCS_BUFF_LEN characters if need be.  This is essential for opost
-	 * writes since they do not do high level buffering and expect to be
-	 * able to send what the driver commits to sending buffering
-	 * [e.g. tab to space conversions in n_tty.c opost()].
-	 */
-	char buffer[HVCS_BUFF_LEN];
-	int chars_in_buffer;
-
-	/*
-	 * Any variable below the kref is valid before a tty is connected and
-	 * stays valid after the tty is disconnected.  These shouldn't be
-	 * whacked until the koject refcount reaches zero though some entries
-	 * may be changed via sysfs initiatives.
-	 */
-	struct kref kref; /* ref count & hvcs_struct lifetime */
-	int connected; /* is the vty-server currently connected to a vty? */
-	uint32_t p_unit_address; /* partner unit address */
-	uint32_t p_partition_ID; /* partner partition ID */
-	char p_location_code[HVCS_CLC_LENGTH + 1]; /* CLC + Null Term */
-	struct list_head next; /* list management */
-	struct vio_dev *vdev;
-};
-
-/* Required to back map a kref to its containing object */
-#define from_kref(k) container_of(k, struct hvcs_struct, kref)
-
-static LIST_HEAD(hvcs_structs);
-static DEFINE_SPINLOCK(hvcs_structs_lock);
-
-static void hvcs_unthrottle(struct tty_struct *tty);
-static void hvcs_throttle(struct tty_struct *tty);
-static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance);
-
-static int hvcs_write(struct tty_struct *tty,
-		const unsigned char *buf, int count);
-static int hvcs_write_room(struct tty_struct *tty);
-static int hvcs_chars_in_buffer(struct tty_struct *tty);
-
-static int hvcs_has_pi(struct hvcs_struct *hvcsd);
-static void hvcs_set_pi(struct hvcs_partner_info *pi,
-		struct hvcs_struct *hvcsd);
-static int hvcs_get_pi(struct hvcs_struct *hvcsd);
-static int hvcs_rescan_devices_list(void);
-
-static int hvcs_partner_connect(struct hvcs_struct *hvcsd);
-static void hvcs_partner_free(struct hvcs_struct *hvcsd);
-
-static int hvcs_enable_device(struct hvcs_struct *hvcsd,
-		uint32_t unit_address, unsigned int irq, struct vio_dev *dev);
-
-static int hvcs_open(struct tty_struct *tty, struct file *filp);
-static void hvcs_close(struct tty_struct *tty, struct file *filp);
-static void hvcs_hangup(struct tty_struct * tty);
-
-static int __devinit hvcs_probe(struct vio_dev *dev,
-		const struct vio_device_id *id);
-static int __devexit hvcs_remove(struct vio_dev *dev);
-static int __init hvcs_module_init(void);
-static void __exit hvcs_module_exit(void);
-
-#define HVCS_SCHED_READ	0x00000001
-#define HVCS_QUICK_READ	0x00000002
-#define HVCS_TRY_WRITE	0x00000004
-#define HVCS_READ_MASK	(HVCS_SCHED_READ | HVCS_QUICK_READ)
-
-static inline struct hvcs_struct *from_vio_dev(struct vio_dev *viod)
-{
-	return dev_get_drvdata(&viod->dev);
-}
-/* The sysfs interface for the driver and devices */
-
-static ssize_t hvcs_partner_vtys_show(struct device *dev, struct device_attribute *attr, char *buf)
-{
-	struct vio_dev *viod = to_vio_dev(dev);
-	struct hvcs_struct *hvcsd = from_vio_dev(viod);
-	unsigned long flags;
-	int retval;
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-	retval = sprintf(buf, "%X\n", hvcsd->p_unit_address);
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-	return retval;
-}
-static DEVICE_ATTR(partner_vtys, S_IRUGO, hvcs_partner_vtys_show, NULL);
-
-static ssize_t hvcs_partner_clcs_show(struct device *dev, struct device_attribute *attr, char *buf)
-{
-	struct vio_dev *viod = to_vio_dev(dev);
-	struct hvcs_struct *hvcsd = from_vio_dev(viod);
-	unsigned long flags;
-	int retval;
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-	retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-	return retval;
-}
-static DEVICE_ATTR(partner_clcs, S_IRUGO, hvcs_partner_clcs_show, NULL);
-
-static ssize_t hvcs_current_vty_store(struct device *dev, struct device_attribute *attr, const char * buf,
-		size_t count)
-{
-	/*
-	 * Don't need this feature at the present time because firmware doesn't
-	 * yet support multiple partners.
-	 */
-	printk(KERN_INFO "HVCS: Denied current_vty change: -EPERM.\n");
-	return -EPERM;
-}
-
-static ssize_t hvcs_current_vty_show(struct device *dev, struct device_attribute *attr, char *buf)
-{
-	struct vio_dev *viod = to_vio_dev(dev);
-	struct hvcs_struct *hvcsd = from_vio_dev(viod);
-	unsigned long flags;
-	int retval;
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-	retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-	return retval;
-}
-
-static DEVICE_ATTR(current_vty,
-	S_IRUGO | S_IWUSR, hvcs_current_vty_show, hvcs_current_vty_store);
-
-static ssize_t hvcs_vterm_state_store(struct device *dev, struct device_attribute *attr, const char *buf,
-		size_t count)
-{
-	struct vio_dev *viod = to_vio_dev(dev);
-	struct hvcs_struct *hvcsd = from_vio_dev(viod);
-	unsigned long flags;
-
-	/* writing a '0' to this sysfs entry will result in the disconnect. */
-	if (simple_strtol(buf, NULL, 0) != 0)
-		return -EINVAL;
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-
-	if (hvcsd->open_count > 0) {
-		spin_unlock_irqrestore(&hvcsd->lock, flags);
-		printk(KERN_INFO "HVCS: vterm state unchanged.  "
-				"The hvcs device node is still in use.\n");
-		return -EPERM;
-	}
-
-	if (hvcsd->connected == 0) {
-		spin_unlock_irqrestore(&hvcsd->lock, flags);
-		printk(KERN_INFO "HVCS: vterm state unchanged. The"
-				" vty-server is not connected to a vty.\n");
-		return -EPERM;
-	}
-
-	hvcs_partner_free(hvcsd);
-	printk(KERN_INFO "HVCS: Closed vty-server@%X and"
-			" partner vty@%X:%d connection.\n",
-			hvcsd->vdev->unit_address,
-			hvcsd->p_unit_address,
-			(uint32_t)hvcsd->p_partition_ID);
-
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-	return count;
-}
-
-static ssize_t hvcs_vterm_state_show(struct device *dev, struct device_attribute *attr, char *buf)
-{
-	struct vio_dev *viod = to_vio_dev(dev);
-	struct hvcs_struct *hvcsd = from_vio_dev(viod);
-	unsigned long flags;
-	int retval;
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-	retval = sprintf(buf, "%d\n", hvcsd->connected);
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-	return retval;
-}
-static DEVICE_ATTR(vterm_state, S_IRUGO | S_IWUSR,
-		hvcs_vterm_state_show, hvcs_vterm_state_store);
-
-static ssize_t hvcs_index_show(struct device *dev, struct device_attribute *attr, char *buf)
-{
-	struct vio_dev *viod = to_vio_dev(dev);
-	struct hvcs_struct *hvcsd = from_vio_dev(viod);
-	unsigned long flags;
-	int retval;
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-	retval = sprintf(buf, "%d\n", hvcsd->index);
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-	return retval;
-}
-
-static DEVICE_ATTR(index, S_IRUGO, hvcs_index_show, NULL);
-
-static struct attribute *hvcs_attrs[] = {
-	&dev_attr_partner_vtys.attr,
-	&dev_attr_partner_clcs.attr,
-	&dev_attr_current_vty.attr,
-	&dev_attr_vterm_state.attr,
-	&dev_attr_index.attr,
-	NULL,
-};
-
-static struct attribute_group hvcs_attr_group = {
-	.attrs = hvcs_attrs,
-};
-
-static ssize_t hvcs_rescan_show(struct device_driver *ddp, char *buf)
-{
-	/* A 1 means it is updating, a 0 means it is done updating */
-	return snprintf(buf, PAGE_SIZE, "%d\n", hvcs_rescan_status);
-}
-
-static ssize_t hvcs_rescan_store(struct device_driver *ddp, const char * buf,
-		size_t count)
-{
-	if ((simple_strtol(buf, NULL, 0) != 1)
-		&& (hvcs_rescan_status != 0))
-		return -EINVAL;
-
-	hvcs_rescan_status = 1;
-	printk(KERN_INFO "HVCS: rescanning partner info for all"
-		" vty-servers.\n");
-	hvcs_rescan_devices_list();
-	hvcs_rescan_status = 0;
-	return count;
-}
-
-static DRIVER_ATTR(rescan,
-	S_IRUGO | S_IWUSR, hvcs_rescan_show, hvcs_rescan_store);
-
-static void hvcs_kick(void)
-{
-	hvcs_kicked = 1;
-	wmb();
-	wake_up_process(hvcs_task);
-}
-
-static void hvcs_unthrottle(struct tty_struct *tty)
-{
-	struct hvcs_struct *hvcsd = tty->driver_data;
-	unsigned long flags;
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-	hvcsd->todo_mask |= HVCS_SCHED_READ;
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-	hvcs_kick();
-}
-
-static void hvcs_throttle(struct tty_struct *tty)
-{
-	struct hvcs_struct *hvcsd = tty->driver_data;
-	unsigned long flags;
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-	vio_disable_interrupts(hvcsd->vdev);
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-}
-
-/*
- * If the device is being removed we don't have to worry about this interrupt
- * handler taking any further interrupts because they are disabled which means
- * the hvcs_struct will always be valid in this handler.
- */
-static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance)
-{
-	struct hvcs_struct *hvcsd = dev_instance;
-
-	spin_lock(&hvcsd->lock);
-	vio_disable_interrupts(hvcsd->vdev);
-	hvcsd->todo_mask |= HVCS_SCHED_READ;
-	spin_unlock(&hvcsd->lock);
-	hvcs_kick();
-
-	return IRQ_HANDLED;
-}
-
-/* This function must be called with the hvcsd->lock held */
-static void hvcs_try_write(struct hvcs_struct *hvcsd)
-{
-	uint32_t unit_address = hvcsd->vdev->unit_address;
-	struct tty_struct *tty = hvcsd->tty;
-	int sent;
-
-	if (hvcsd->todo_mask & HVCS_TRY_WRITE) {
-		/* won't send partial writes */
-		sent = hvc_put_chars(unit_address,
-				&hvcsd->buffer[0],
-				hvcsd->chars_in_buffer );
-		if (sent > 0) {
-			hvcsd->chars_in_buffer = 0;
-			/* wmb(); */
-			hvcsd->todo_mask &= ~(HVCS_TRY_WRITE);
-			/* wmb(); */
-
-			/*
-			 * We are still obligated to deliver the data to the
-			 * hypervisor even if the tty has been closed because
-			 * we commited to delivering it.  But don't try to wake
-			 * a non-existent tty.
-			 */
-			if (tty) {
-				tty_wakeup(tty);
-			}
-		}
-	}
-}
-
-static int hvcs_io(struct hvcs_struct *hvcsd)
-{
-	uint32_t unit_address;
-	struct tty_struct *tty;
-	char buf[HVCS_BUFF_LEN] __ALIGNED__;
-	unsigned long flags;
-	int got = 0;
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-
-	unit_address = hvcsd->vdev->unit_address;
-	tty = hvcsd->tty;
-
-	hvcs_try_write(hvcsd);
-
-	if (!tty || test_bit(TTY_THROTTLED, &tty->flags)) {
-		hvcsd->todo_mask &= ~(HVCS_READ_MASK);
-		goto bail;
-	} else if (!(hvcsd->todo_mask & (HVCS_READ_MASK)))
-		goto bail;
-
-	/* remove the read masks */
-	hvcsd->todo_mask &= ~(HVCS_READ_MASK);
-
-	if (tty_buffer_request_room(tty, HVCS_BUFF_LEN) >= HVCS_BUFF_LEN) {
-		got = hvc_get_chars(unit_address,
-				&buf[0],
-				HVCS_BUFF_LEN);
-		tty_insert_flip_string(tty, buf, got);
-	}
-
-	/* Give the TTY time to process the data we just sent. */
-	if (got)
-		hvcsd->todo_mask |= HVCS_QUICK_READ;
-
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-	/* This is synch because tty->low_latency == 1 */
-	if(got)
-		tty_flip_buffer_push(tty);
-
-	if (!got) {
-		/* Do this _after_ the flip_buffer_push */
-		spin_lock_irqsave(&hvcsd->lock, flags);
-		vio_enable_interrupts(hvcsd->vdev);
-		spin_unlock_irqrestore(&hvcsd->lock, flags);
-	}
-
-	return hvcsd->todo_mask;
-
- bail:
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-	return hvcsd->todo_mask;
-}
-
-static int khvcsd(void *unused)
-{
-	struct hvcs_struct *hvcsd;
-	int hvcs_todo_mask;
-
-	__set_current_state(TASK_RUNNING);
-
-	do {
-		hvcs_todo_mask = 0;
-		hvcs_kicked = 0;
-		wmb();
-
-		spin_lock(&hvcs_structs_lock);
-		list_for_each_entry(hvcsd, &hvcs_structs, next) {
-			hvcs_todo_mask |= hvcs_io(hvcsd);
-		}
-		spin_unlock(&hvcs_structs_lock);
-
-		/*
-		 * If any of the hvcs adapters want to try a write or quick read
-		 * don't schedule(), yield a smidgen then execute the hvcs_io
-		 * thread again for those that want the write.
-		 */
-		 if (hvcs_todo_mask & (HVCS_TRY_WRITE | HVCS_QUICK_READ)) {
-			yield();
-			continue;
-		}
-
-		set_current_state(TASK_INTERRUPTIBLE);
-		if (!hvcs_kicked)
-			schedule();
-		__set_current_state(TASK_RUNNING);
-	} while (!kthread_should_stop());
-
-	return 0;
-}
-
-static struct vio_device_id hvcs_driver_table[] __devinitdata= {
-	{"serial-server", "hvterm2"},
-	{ "", "" }
-};
-MODULE_DEVICE_TABLE(vio, hvcs_driver_table);
-
-static void hvcs_return_index(int index)
-{
-	/* Paranoia check */
-	if (!hvcs_index_list)
-		return;
-	if (index < 0 || index >= hvcs_index_count)
-		return;
-	if (hvcs_index_list[index] == -1)
-		return;
-	else
-		hvcs_index_list[index] = -1;
-}
-
-/* callback when the kref ref count reaches zero */
-static void destroy_hvcs_struct(struct kref *kref)
-{
-	struct hvcs_struct *hvcsd = from_kref(kref);
-	struct vio_dev *vdev;
-	unsigned long flags;
-
-	spin_lock(&hvcs_structs_lock);
-	spin_lock_irqsave(&hvcsd->lock, flags);
-
-	/* the list_del poisons the pointers */
-	list_del(&(hvcsd->next));
-
-	if (hvcsd->connected == 1) {
-		hvcs_partner_free(hvcsd);
-		printk(KERN_INFO "HVCS: Closed vty-server@%X and"
-				" partner vty@%X:%d connection.\n",
-				hvcsd->vdev->unit_address,
-				hvcsd->p_unit_address,
-				(uint32_t)hvcsd->p_partition_ID);
-	}
-	printk(KERN_INFO "HVCS: Destroyed hvcs_struct for vty-server@%X.\n",
-			hvcsd->vdev->unit_address);
-
-	vdev = hvcsd->vdev;
-	hvcsd->vdev = NULL;
-
-	hvcsd->p_unit_address = 0;
-	hvcsd->p_partition_ID = 0;
-	hvcs_return_index(hvcsd->index);
-	memset(&hvcsd->p_location_code[0], 0x00, HVCS_CLC_LENGTH + 1);
-
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-	spin_unlock(&hvcs_structs_lock);
-
-	sysfs_remove_group(&vdev->dev.kobj, &hvcs_attr_group);
-
-	kfree(hvcsd);
-}
-
-static int hvcs_get_index(void)
-{
-	int i;
-	/* Paranoia check */
-	if (!hvcs_index_list) {
-		printk(KERN_ERR "HVCS: hvcs_index_list NOT valid!.\n");
-		return -EFAULT;
-	}
-	/* Find the numerically lowest first free index. */
-	for(i = 0; i < hvcs_index_count; i++) {
-		if (hvcs_index_list[i] == -1) {
-			hvcs_index_list[i] = 0;
-			return i;
-		}
-	}
-	return -1;
-}
-
-static int __devinit hvcs_probe(
-	struct vio_dev *dev,
-	const struct vio_device_id *id)
-{
-	struct hvcs_struct *hvcsd;
-	int index;
-	int retval;
-
-	if (!dev || !id) {
-		printk(KERN_ERR "HVCS: probed with invalid parameter.\n");
-		return -EPERM;
-	}
-
-	/* early to avoid cleanup on failure */
-	index = hvcs_get_index();
-	if (index < 0) {
-		return -EFAULT;
-	}
-
-	hvcsd = kzalloc(sizeof(*hvcsd), GFP_KERNEL);
-	if (!hvcsd)
-		return -ENODEV;
-
-
-	spin_lock_init(&hvcsd->lock);
-	/* Automatically incs the refcount the first time */
-	kref_init(&hvcsd->kref);
-
-	hvcsd->vdev = dev;
-	dev_set_drvdata(&dev->dev, hvcsd);
-
-	hvcsd->index = index;
-
-	/* hvcsd->index = ++hvcs_struct_count; */
-	hvcsd->chars_in_buffer = 0;
-	hvcsd->todo_mask = 0;
-	hvcsd->connected = 0;
-
-	/*
-	 * This will populate the hvcs_struct's partner info fields for the
-	 * first time.
-	 */
-	if (hvcs_get_pi(hvcsd)) {
-		printk(KERN_ERR "HVCS: Failed to fetch partner"
-			" info for vty-server@%X on device probe.\n",
-			hvcsd->vdev->unit_address);
-	}
-
-	/*
-	 * If a user app opens a tty that corresponds to this vty-server before
-	 * the hvcs_struct has been added to the devices list then the user app
-	 * will get -ENODEV.
-	 */
-	spin_lock(&hvcs_structs_lock);
-	list_add_tail(&(hvcsd->next), &hvcs_structs);
-	spin_unlock(&hvcs_structs_lock);
-
-	retval = sysfs_create_group(&dev->dev.kobj, &hvcs_attr_group);
-	if (retval) {
-		printk(KERN_ERR "HVCS: Can't create sysfs attrs for vty-server@%X\n",
-		       hvcsd->vdev->unit_address);
-		return retval;
-	}
-
-	printk(KERN_INFO "HVCS: vty-server@%X added to the vio bus.\n", dev->unit_address);
-
-	/*
-	 * DON'T enable interrupts here because there is no user to receive the
-	 * data.
-	 */
-	return 0;
-}
-
-static int __devexit hvcs_remove(struct vio_dev *dev)
-{
-	struct hvcs_struct *hvcsd = dev_get_drvdata(&dev->dev);
-	unsigned long flags;
-	struct tty_struct *tty;
-
-	if (!hvcsd)
-		return -ENODEV;
-
-	/* By this time the vty-server won't be getting any more interrupts */
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-
-	tty = hvcsd->tty;
-
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-
-	/*
-	 * Let the last holder of this object cause it to be removed, which
-	 * would probably be tty_hangup below.
-	 */
-	kref_put(&hvcsd->kref, destroy_hvcs_struct);
-
-	/*
-	 * The hangup is a scheduled function which will auto chain call
-	 * hvcs_hangup.  The tty should always be valid at this time unless a
-	 * simultaneous tty close already cleaned up the hvcs_struct.
-	 */
-	if (tty)
-		tty_hangup(tty);
-
-	printk(KERN_INFO "HVCS: vty-server@%X removed from the"
-			" vio bus.\n", dev->unit_address);
-	return 0;
-};
-
-static struct vio_driver hvcs_vio_driver = {
-	.id_table	= hvcs_driver_table,
-	.probe		= hvcs_probe,
-	.remove		= __devexit_p(hvcs_remove),
-	.driver		= {
-		.name	= hvcs_driver_name,
-		.owner	= THIS_MODULE,
-	}
-};
-
-/* Only called from hvcs_get_pi please */
-static void hvcs_set_pi(struct hvcs_partner_info *pi, struct hvcs_struct *hvcsd)
-{
-	int clclength;
-
-	hvcsd->p_unit_address = pi->unit_address;
-	hvcsd->p_partition_ID  = pi->partition_ID;
-	clclength = strlen(&pi->location_code[0]);
-	if (clclength > HVCS_CLC_LENGTH)
-		clclength = HVCS_CLC_LENGTH;
-
-	/* copy the null-term char too */
-	strncpy(&hvcsd->p_location_code[0],
-			&pi->location_code[0], clclength + 1);
-}
-
-/*
- * Traverse the list and add the partner info that is found to the hvcs_struct
- * struct entry. NOTE: At this time I know that partner info will return a
- * single entry but in the future there may be multiple partner info entries per
- * vty-server and you'll want to zero out that list and reset it.  If for some
- * reason you have an old version of this driver but there IS more than one
- * partner info then hvcsd->p_* will hold the last partner info data from the
- * firmware query.  A good way to update this code would be to replace the three
- * partner info fields in hvcs_struct with a list of hvcs_partner_info
- * instances.
- *
- * This function must be called with the hvcsd->lock held.
- */
-static int hvcs_get_pi(struct hvcs_struct *hvcsd)
-{
-	struct hvcs_partner_info *pi;
-	uint32_t unit_address = hvcsd->vdev->unit_address;
-	struct list_head head;
-	int retval;
-
-	spin_lock(&hvcs_pi_lock);
-	if (!hvcs_pi_buff) {
-		spin_unlock(&hvcs_pi_lock);
-		return -EFAULT;
-	}
-	retval = hvcs_get_partner_info(unit_address, &head, hvcs_pi_buff);
-	spin_unlock(&hvcs_pi_lock);
-	if (retval) {
-		printk(KERN_ERR "HVCS: Failed to fetch partner"
-			" info for vty-server@%x.\n", unit_address);
-		return retval;
-	}
-
-	/* nixes the values if the partner vty went away */
-	hvcsd->p_unit_address = 0;
-	hvcsd->p_partition_ID = 0;
-
-	list_for_each_entry(pi, &head, node)
-		hvcs_set_pi(pi, hvcsd);
-
-	hvcs_free_partner_info(&head);
-	return 0;
-}
-
-/*
- * This function is executed by the driver "rescan" sysfs entry.  It shouldn't
- * be executed elsewhere, in order to prevent deadlock issues.
- */
-static int hvcs_rescan_devices_list(void)
-{
-	struct hvcs_struct *hvcsd;
-	unsigned long flags;
-
-	spin_lock(&hvcs_structs_lock);
-
-	list_for_each_entry(hvcsd, &hvcs_structs, next) {
-		spin_lock_irqsave(&hvcsd->lock, flags);
-		hvcs_get_pi(hvcsd);
-		spin_unlock_irqrestore(&hvcsd->lock, flags);
-	}
-
-	spin_unlock(&hvcs_structs_lock);
-
-	return 0;
-}
-
-/*
- * Farm this off into its own function because it could be more complex once
- * multiple partners support is added. This function should be called with
- * the hvcsd->lock held.
- */
-static int hvcs_has_pi(struct hvcs_struct *hvcsd)
-{
-	if ((!hvcsd->p_unit_address) || (!hvcsd->p_partition_ID))
-		return 0;
-	return 1;
-}
-
-/*
- * NOTE: It is possible that the super admin removed a partner vty and then
- * added a different vty as the new partner.
- *
- * This function must be called with the hvcsd->lock held.
- */
-static int hvcs_partner_connect(struct hvcs_struct *hvcsd)
-{
-	int retval;
-	unsigned int unit_address = hvcsd->vdev->unit_address;
-
-	/*
-	 * If there wasn't any pi when the device was added it doesn't meant
-	 * there isn't any now.  This driver isn't notified when a new partner
-	 * vty is added to a vty-server so we discover changes on our own.
-	 * Please see comments in hvcs_register_connection() for justification
-	 * of this bizarre code.
-	 */
-	retval = hvcs_register_connection(unit_address,
-			hvcsd->p_partition_ID,
-			hvcsd->p_unit_address);
-	if (!retval) {
-		hvcsd->connected = 1;
-		return 0;
-	} else if (retval != -EINVAL)
-		return retval;
-
-	/*
-	 * As per the spec re-get the pi and try again if -EINVAL after the
-	 * first connection attempt.
-	 */
-	if (hvcs_get_pi(hvcsd))
-		return -ENOMEM;
-
-	if (!hvcs_has_pi(hvcsd))
-		return -ENODEV;
-
-	retval = hvcs_register_connection(unit_address,
-			hvcsd->p_partition_ID,
-			hvcsd->p_unit_address);
-	if (retval != -EINVAL) {
-		hvcsd->connected = 1;
-		return retval;
-	}
-
-	/*
-	 * EBUSY is the most likely scenario though the vty could have been
-	 * removed or there really could be an hcall error due to the parameter
-	 * data but thanks to ambiguous firmware return codes we can't really
-	 * tell.
-	 */
-	printk(KERN_INFO "HVCS: vty-server or partner"
-			" vty is busy.  Try again later.\n");
-	return -EBUSY;
-}
-
-/* This function must be called with the hvcsd->lock held */
-static void hvcs_partner_free(struct hvcs_struct *hvcsd)
-{
-	int retval;
-	do {
-		retval = hvcs_free_connection(hvcsd->vdev->unit_address);
-	} while (retval == -EBUSY);
-	hvcsd->connected = 0;
-}
-
-/* This helper function must be called WITHOUT the hvcsd->lock held */
-static int hvcs_enable_device(struct hvcs_struct *hvcsd, uint32_t unit_address,
-		unsigned int irq, struct vio_dev *vdev)
-{
-	unsigned long flags;
-	int rc;
-
-	/*
-	 * It is possible that the vty-server was removed between the time that
-	 * the conn was registered and now.
-	 */
-	if (!(rc = request_irq(irq, &hvcs_handle_interrupt,
-				IRQF_DISABLED, "ibmhvcs", hvcsd))) {
-		/*
-		 * It is possible the vty-server was removed after the irq was
-		 * requested but before we have time to enable interrupts.
-		 */
-		if (vio_enable_interrupts(vdev) == H_SUCCESS)
-			return 0;
-		else {
-			printk(KERN_ERR "HVCS: int enable failed for"
-					" vty-server@%X.\n", unit_address);
-			free_irq(irq, hvcsd);
-		}
-	} else
-		printk(KERN_ERR "HVCS: irq req failed for"
-				" vty-server@%X.\n", unit_address);
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-	hvcs_partner_free(hvcsd);
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-
-	return rc;
-
-}
-
-/*
- * This always increments the kref ref count if the call is successful.
- * Please remember to dec when you are done with the instance.
- *
- * NOTICE: Do NOT hold either the hvcs_struct.lock or hvcs_structs_lock when
- * calling this function or you will get deadlock.
- */
-static struct hvcs_struct *hvcs_get_by_index(int index)
-{
-	struct hvcs_struct *hvcsd = NULL;
-	unsigned long flags;
-
-	spin_lock(&hvcs_structs_lock);
-	/* We can immediately discard OOB requests */
-	if (index >= 0 && index < HVCS_MAX_SERVER_ADAPTERS) {
-		list_for_each_entry(hvcsd, &hvcs_structs, next) {
-			spin_lock_irqsave(&hvcsd->lock, flags);
-			if (hvcsd->index == index) {
-				kref_get(&hvcsd->kref);
-				spin_unlock_irqrestore(&hvcsd->lock, flags);
-				spin_unlock(&hvcs_structs_lock);
-				return hvcsd;
-			}
-			spin_unlock_irqrestore(&hvcsd->lock, flags);
-		}
-		hvcsd = NULL;
-	}
-
-	spin_unlock(&hvcs_structs_lock);
-	return hvcsd;
-}
-
-/*
- * This is invoked via the tty_open interface when a user app connects to the
- * /dev node.
- */
-static int hvcs_open(struct tty_struct *tty, struct file *filp)
-{
-	struct hvcs_struct *hvcsd;
-	int rc, retval = 0;
-	unsigned long flags;
-	unsigned int irq;
-	struct vio_dev *vdev;
-	unsigned long unit_address;
-
-	if (tty->driver_data)
-		goto fast_open;
-
-	/*
-	 * Is there a vty-server that shares the same index?
-	 * This function increments the kref index.
-	 */
-	if (!(hvcsd = hvcs_get_by_index(tty->index))) {
-		printk(KERN_WARNING "HVCS: open failed, no device associated"
-				" with tty->index %d.\n", tty->index);
-		return -ENODEV;
-	}
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-
-	if (hvcsd->connected == 0)
-		if ((retval = hvcs_partner_connect(hvcsd)))
-			goto error_release;
-
-	hvcsd->open_count = 1;
-	hvcsd->tty = tty;
-	tty->driver_data = hvcsd;
-
-	memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
-
-	/*
-	 * Save these in the spinlock for the enable operations that need them
-	 * outside of the spinlock.
-	 */
-	irq = hvcsd->vdev->irq;
-	vdev = hvcsd->vdev;
-	unit_address = hvcsd->vdev->unit_address;
-
-	hvcsd->todo_mask |= HVCS_SCHED_READ;
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-
-	/*
-	 * This must be done outside of the spinlock because it requests irqs
-	 * and will grab the spinlock and free the connection if it fails.
-	 */
-	if (((rc = hvcs_enable_device(hvcsd, unit_address, irq, vdev)))) {
-		kref_put(&hvcsd->kref, destroy_hvcs_struct);
-		printk(KERN_WARNING "HVCS: enable device failed.\n");
-		return rc;
-	}
-
-	goto open_success;
-
-fast_open:
-	hvcsd = tty->driver_data;
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-	kref_get(&hvcsd->kref);
-	hvcsd->open_count++;
-	hvcsd->todo_mask |= HVCS_SCHED_READ;
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-
-open_success:
-	hvcs_kick();
-
-	printk(KERN_INFO "HVCS: vty-server@%X connection opened.\n",
-		hvcsd->vdev->unit_address );
-
-	return 0;
-
-error_release:
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-	kref_put(&hvcsd->kref, destroy_hvcs_struct);
-
-	printk(KERN_WARNING "HVCS: partner connect failed.\n");
-	return retval;
-}
-
-static void hvcs_close(struct tty_struct *tty, struct file *filp)
-{
-	struct hvcs_struct *hvcsd;
-	unsigned long flags;
-	int irq = NO_IRQ;
-
-	/*
-	 * Is someone trying to close the file associated with this device after
-	 * we have hung up?  If so tty->driver_data wouldn't be valid.
-	 */
-	if (tty_hung_up_p(filp))
-		return;
-
-	/*
-	 * No driver_data means that this close was probably issued after a
-	 * failed hvcs_open by the tty layer's release_dev() api and we can just
-	 * exit cleanly.
-	 */
-	if (!tty->driver_data)
-		return;
-
-	hvcsd = tty->driver_data;
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-	if (--hvcsd->open_count == 0) {
-
-		vio_disable_interrupts(hvcsd->vdev);
-
-		/*
-		 * NULL this early so that the kernel_thread doesn't try to
-		 * execute any operations on the TTY even though it is obligated
-		 * to deliver any pending I/O to the hypervisor.
-		 */
-		hvcsd->tty = NULL;
-
-		irq = hvcsd->vdev->irq;
-		spin_unlock_irqrestore(&hvcsd->lock, flags);
-
-		tty_wait_until_sent(tty, HVCS_CLOSE_WAIT);
-
-		/*
-		 * This line is important because it tells hvcs_open that this
-		 * device needs to be re-configured the next time hvcs_open is
-		 * called.
-		 */
-		tty->driver_data = NULL;
-
-		free_irq(irq, hvcsd);
-		kref_put(&hvcsd->kref, destroy_hvcs_struct);
-		return;
-	} else if (hvcsd->open_count < 0) {
-		printk(KERN_ERR "HVCS: vty-server@%X open_count: %d"
-				" is missmanaged.\n",
-		hvcsd->vdev->unit_address, hvcsd->open_count);
-	}
-
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-	kref_put(&hvcsd->kref, destroy_hvcs_struct);
-}
-
-static void hvcs_hangup(struct tty_struct * tty)
-{
-	struct hvcs_struct *hvcsd = tty->driver_data;
-	unsigned long flags;
-	int temp_open_count;
-	int irq = NO_IRQ;
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-	/* Preserve this so that we know how many kref refs to put */
-	temp_open_count = hvcsd->open_count;
-
-	/*
-	 * Don't kref put inside the spinlock because the destruction
-	 * callback may use the spinlock and it may get called before the
-	 * spinlock has been released.
-	 */
-	vio_disable_interrupts(hvcsd->vdev);
-
-	hvcsd->todo_mask = 0;
-
-	/* I don't think the tty needs the hvcs_struct pointer after a hangup */
-	hvcsd->tty->driver_data = NULL;
-	hvcsd->tty = NULL;
-
-	hvcsd->open_count = 0;
-
-	/* This will drop any buffered data on the floor which is OK in a hangup
-	 * scenario. */
-	memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
-	hvcsd->chars_in_buffer = 0;
-
-	irq = hvcsd->vdev->irq;
-
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-
-	free_irq(irq, hvcsd);
-
-	/*
-	 * We need to kref_put() for every open_count we have since the
-	 * tty_hangup() function doesn't invoke a close per open connection on a
-	 * non-console device.
-	 */
-	while(temp_open_count) {
-		--temp_open_count;
-		/*
-		 * The final put will trigger destruction of the hvcs_struct.
-		 * NOTE:  If this hangup was signaled from user space then the
-		 * final put will never happen.
-		 */
-		kref_put(&hvcsd->kref, destroy_hvcs_struct);
-	}
-}
-
-/*
- * NOTE: This is almost always from_user since user level apps interact with the
- * /dev nodes. I'm trusting that if hvcs_write gets called and interrupted by
- * hvcs_remove (which removes the target device and executes tty_hangup()) that
- * tty_hangup will allow hvcs_write time to complete execution before it
- * terminates our device.
- */
-static int hvcs_write(struct tty_struct *tty,
-		const unsigned char *buf, int count)
-{
-	struct hvcs_struct *hvcsd = tty->driver_data;
-	unsigned int unit_address;
-	const unsigned char *charbuf;
-	unsigned long flags;
-	int total_sent = 0;
-	int tosend = 0;
-	int result = 0;
-
-	/*
-	 * If they don't check the return code off of their open they may
-	 * attempt this even if there is no connected device.
-	 */
-	if (!hvcsd)
-		return -ENODEV;
-
-	/* Reasonable size to prevent user level flooding */
-	if (count > HVCS_MAX_FROM_USER) {
-		printk(KERN_WARNING "HVCS write: count being truncated to"
-				" HVCS_MAX_FROM_USER.\n");
-		count = HVCS_MAX_FROM_USER;
-	}
-
-	charbuf = buf;
-
-	spin_lock_irqsave(&hvcsd->lock, flags);
-
-	/*
-	 * Somehow an open succedded but the device was removed or the
-	 * connection terminated between the vty-server and partner vty during
-	 * the middle of a write operation?  This is a crummy place to do this
-	 * but we want to keep it all in the spinlock.
-	 */
-	if (hvcsd->open_count <= 0) {
-		spin_unlock_irqrestore(&hvcsd->lock, flags);
-		return -ENODEV;
-	}
-
-	unit_address = hvcsd->vdev->unit_address;
-
-	while (count > 0) {
-		tosend = min(count, (HVCS_BUFF_LEN - hvcsd->chars_in_buffer));
-		/*
-		 * No more space, this probably means that the last call to
-		 * hvcs_write() didn't succeed and the buffer was filled up.
-		 */
-		if (!tosend)
-			break;
-
-		memcpy(&hvcsd->buffer[hvcsd->chars_in_buffer],
-				&charbuf[total_sent],
-				tosend);
-
-		hvcsd->chars_in_buffer += tosend;
-
-		result = 0;
-
-		/*
-		 * If this is true then we don't want to try writing to the
-		 * hypervisor because that is the kernel_threads job now.  We'll
-		 * just add to the buffer.
-		 */
-		if (!(hvcsd->todo_mask & HVCS_TRY_WRITE))
-			/* won't send partial writes */
-			result = hvc_put_chars(unit_address,
-					&hvcsd->buffer[0],
-					hvcsd->chars_in_buffer);
-
-		/*
-		 * Since we know we have enough room in hvcsd->buffer for
-		 * tosend we record that it was sent regardless of whether the
-		 * hypervisor actually took it because we have it buffered.
-		 */
-		total_sent+=tosend;
-		count-=tosend;
-		if (result == 0) {
-			hvcsd->todo_mask |= HVCS_TRY_WRITE;
-			hvcs_kick();
-			break;
-		}
-
-		hvcsd->chars_in_buffer = 0;
-		/*
-		 * Test after the chars_in_buffer reset otherwise this could
-		 * deadlock our writes if hvc_put_chars fails.
-		 */
-		if (result < 0)
-			break;
-	}
-
-	spin_unlock_irqrestore(&hvcsd->lock, flags);
-
-	if (result == -1)
-		return -EIO;
-	else
-		return total_sent;
-}
-
-/*
- * This is really asking how much can we guarentee that we can send or that we
- * absolutely WILL BUFFER if we can't send it.  This driver MUST honor the
- * return value, hence the reason for hvcs_struct buffering.
- */
-static int hvcs_write_room(struct tty_struct *tty)
-{
-	struct hvcs_struct *hvcsd = tty->driver_data;
-
-	if (!hvcsd || hvcsd->open_count <= 0)
-		return 0;
-
-	return HVCS_BUFF_LEN - hvcsd->chars_in_buffer;
-}
-
-static int hvcs_chars_in_buffer(struct tty_struct *tty)
-{
-	struct hvcs_struct *hvcsd = tty->driver_data;
-
-	return hvcsd->chars_in_buffer;
-}
-
-static const struct tty_operations hvcs_ops = {
-	.open = hvcs_open,
-	.close = hvcs_close,
-	.hangup = hvcs_hangup,
-	.write = hvcs_write,
-	.write_room = hvcs_write_room,
-	.chars_in_buffer = hvcs_chars_in_buffer,
-	.unthrottle = hvcs_unthrottle,
-	.throttle = hvcs_throttle,
-};
-
-static int hvcs_alloc_index_list(int n)
-{
-	int i;
-
-	hvcs_index_list = kmalloc(n * sizeof(hvcs_index_count),GFP_KERNEL);
-	if (!hvcs_index_list)
-		return -ENOMEM;
-	hvcs_index_count = n;
-	for (i = 0; i < hvcs_index_count; i++)
-		hvcs_index_list[i] = -1;
-	return 0;
-}
-
-static void hvcs_free_index_list(void)
-{
-	/* Paranoia check to be thorough. */
-	kfree(hvcs_index_list);
-	hvcs_index_list = NULL;
-	hvcs_index_count = 0;
-}
-
-static int __init hvcs_module_init(void)
-{
-	int rc;
-	int num_ttys_to_alloc;
-
-	printk(KERN_INFO "Initializing %s\n", hvcs_driver_string);
-
-	/* Has the user specified an overload with an insmod param? */
-	if (hvcs_parm_num_devs <= 0 ||
-		(hvcs_parm_num_devs > HVCS_MAX_SERVER_ADAPTERS)) {
-		num_ttys_to_alloc = HVCS_DEFAULT_SERVER_ADAPTERS;
-	} else
-		num_ttys_to_alloc = hvcs_parm_num_devs;
-
-	hvcs_tty_driver = alloc_tty_driver(num_ttys_to_alloc);
-	if (!hvcs_tty_driver)
-		return -ENOMEM;
-
-	if (hvcs_alloc_index_list(num_ttys_to_alloc)) {
-		rc = -ENOMEM;
-		goto index_fail;
-	}
-
-	hvcs_tty_driver->owner = THIS_MODULE;
-
-	hvcs_tty_driver->driver_name = hvcs_driver_name;
-	hvcs_tty_driver->name = hvcs_device_node;
-
-	/*
-	 * We'll let the system assign us a major number, indicated by leaving
-	 * it blank.
-	 */
-
-	hvcs_tty_driver->minor_start = HVCS_MINOR_START;
-	hvcs_tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
-
-	/*
-	 * We role our own so that we DONT ECHO.  We can't echo because the
-	 * device we are connecting to already echoes by default and this would
-	 * throw us into a horrible recursive echo-echo-echo loop.
-	 */
-	hvcs_tty_driver->init_termios = hvcs_tty_termios;
-	hvcs_tty_driver->flags = TTY_DRIVER_REAL_RAW;
-
-	tty_set_operations(hvcs_tty_driver, &hvcs_ops);
-
-	/*
-	 * The following call will result in sysfs entries that denote the
-	 * dynamically assigned major and minor numbers for our devices.
-	 */
-	if (tty_register_driver(hvcs_tty_driver)) {
-		printk(KERN_ERR "HVCS: registration as a tty driver failed.\n");
-		rc = -EIO;
-		goto register_fail;
-	}
-
-	hvcs_pi_buff = kmalloc(PAGE_SIZE, GFP_KERNEL);
-	if (!hvcs_pi_buff) {
-		rc = -ENOMEM;
-		goto buff_alloc_fail;
-	}
-
-	hvcs_task = kthread_run(khvcsd, NULL, "khvcsd");
-	if (IS_ERR(hvcs_task)) {
-		printk(KERN_ERR "HVCS: khvcsd creation failed.  Driver not loaded.\n");
-		rc = -EIO;
-		goto kthread_fail;
-	}
-
-	rc = vio_register_driver(&hvcs_vio_driver);
-	if (rc) {
-		printk(KERN_ERR "HVCS: can't register vio driver\n");
-		goto vio_fail;
-	}
-
-	/*
-	 * This needs to be done AFTER the vio_register_driver() call or else
-	 * the kobjects won't be initialized properly.
-	 */
-	rc = driver_create_file(&(hvcs_vio_driver.driver), &driver_attr_rescan);
-	if (rc) {
-		printk(KERN_ERR "HVCS: sysfs attr create failed\n");
-		goto attr_fail;
-	}
-
-	printk(KERN_INFO "HVCS: driver module inserted.\n");
-
-	return 0;
-
-attr_fail:
-	vio_unregister_driver(&hvcs_vio_driver);
-vio_fail:
-	kthread_stop(hvcs_task);
-kthread_fail:
-	kfree(hvcs_pi_buff);
-buff_alloc_fail:
-	tty_unregister_driver(hvcs_tty_driver);
-register_fail:
-	hvcs_free_index_list();
-index_fail:
-	put_tty_driver(hvcs_tty_driver);
-	hvcs_tty_driver = NULL;
-	return rc;
-}
-
-static void __exit hvcs_module_exit(void)
-{
-	/*
-	 * This driver receives hvcs_remove callbacks for each device upon
-	 * module removal.
-	 */
-
-	/*
-	 * This synchronous operation  will wake the khvcsd kthread if it is
-	 * asleep and will return when khvcsd has terminated.
-	 */
-	kthread_stop(hvcs_task);
-
-	spin_lock(&hvcs_pi_lock);
-	kfree(hvcs_pi_buff);
-	hvcs_pi_buff = NULL;
-	spin_unlock(&hvcs_pi_lock);
-
-	driver_remove_file(&hvcs_vio_driver.driver, &driver_attr_rescan);
-
-	vio_unregister_driver(&hvcs_vio_driver);
-
-	tty_unregister_driver(hvcs_tty_driver);
-
-	hvcs_free_index_list();
-
-	put_tty_driver(hvcs_tty_driver);
-
-	printk(KERN_INFO "HVCS: driver module removed.\n");
-}
-
-module_init(hvcs_module_init);
-module_exit(hvcs_module_exit);