1/*
   2 * IBM eServer Hypervisor Virtual Console Server Device Driver
   3 * Copyright (C) 2003, 2004 IBM Corp.
   4 *  Ryan S. Arnold (rsa@us.ibm.com)
   5 *
   6 *  This program is free software; you can redistribute it and/or modify
   7 *  it under the terms of the GNU General Public License as published by
   8 *  the Free Software Foundation; either version 2 of the License, or
   9 *  (at your option) any later version.
  10 *
  11 *  This program is distributed in the hope that it will be useful,
  12 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 *  GNU General Public License for more details.
  15 *
  16 *  You should have received a copy of the GNU General Public License
  17 *  along with this program; if not, write to the Free Software
  18 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  19 *
  20 * Author(s) :  Ryan S. Arnold <rsa@us.ibm.com>
  21 *
  22 * This is the device driver for the IBM Hypervisor Virtual Console Server,
  23 * "hvcs".  The IBM hvcs provides a tty driver interface to allow Linux
  24 * user space applications access to the system consoles of logically
  25 * partitioned operating systems, e.g. Linux, running on the same partitioned
  26 * Power5 ppc64 system.  Physical hardware consoles per partition are not
  27 * practical on this hardware so system consoles are accessed by this driver
  28 * using inter-partition firmware interfaces to virtual terminal devices.
  29 *
  30 * A vty is known to the HMC as a "virtual serial server adapter".  It is a
  31 * virtual terminal device that is created by firmware upon partition creation
  32 * to act as a partitioned OS's console device.
  33 *
  34 * Firmware dynamically (via hotplug) exposes vty-servers to a running ppc64
  35 * Linux system upon their creation by the HMC or their exposure during boot.
  36 * The non-user interactive backend of this driver is implemented as a vio
  37 * device driver so that it can receive notification of vty-server lifetimes
  38 * after it registers with the vio bus to handle vty-server probe and remove
  39 * callbacks.
  40 *
  41 * Many vty-servers can be configured to connect to one vty, but a vty can
  42 * only be actively connected to by a single vty-server, in any manner, at one
  43 * time.  If the HMC is currently hosting the console for a target Linux
  44 * partition; attempts to open the tty device to the partition's console using
  45 * the hvcs on any partition will return -EBUSY with every open attempt until
  46 * the HMC frees the connection between its vty-server and the desired
  47 * partition's vty device.  Conversely, a vty-server may only be connected to
  48 * a single vty at one time even though it may have several configured vty
  49 * partner possibilities.
  50 *
  51 * Firmware does not provide notification of vty partner changes to this
  52 * driver.  This means that an HMC Super Admin may add or remove partner vtys
  53 * from a vty-server's partner list but the changes will not be signaled to
  54 * the vty-server.  Firmware only notifies the driver when a vty-server is
  55 * added or removed from the system.  To compensate for this deficiency, this
  56 * driver implements a sysfs update attribute which provides a method for
  57 * rescanning partner information upon a user's request.
  58 *
  59 * Each vty-server, prior to being exposed to this driver is reference counted
  60 * using the 2.6 Linux kernel kref construct.
  61 *
  62 * For direction on installation and usage of this driver please reference
  63 * Documentation/powerpc/hvcs.txt.
  64 */
  65
  66#include <linux/device.h>
  67#include <linux/init.h>
  68#include <linux/interrupt.h>
  69#include <linux/kernel.h>
  70#include <linux/kref.h>
  71#include <linux/kthread.h>
  72#include <linux/list.h>
  73#include <linux/major.h>
  74#include <linux/module.h>
  75#include <linux/moduleparam.h>
  76#include <linux/sched.h>
  77#include <linux/slab.h>
  78#include <linux/spinlock.h>
  79#include <linux/stat.h>
  80#include <linux/tty.h>
  81#include <linux/tty_flip.h>
  82#include <asm/hvconsole.h>
  83#include <asm/hvcserver.h>
  84#include <asm/uaccess.h>
  85#include <asm/vio.h>
  86
  87/*
  88 * 1.3.0 -> 1.3.1 In hvcs_open memset(..,0x00,..) instead of memset(..,0x3F,00).
  89 * Removed braces around single statements following conditionals.  Removed '=
  90 * 0' after static int declarations since these default to zero.  Removed
  91 * list_for_each_safe() and replaced with list_for_each_entry() in
  92 * hvcs_get_by_index().  The 'safe' version is un-needed now that the driver is
  93 * using spinlocks.  Changed spin_lock_irqsave() to spin_lock() when locking
  94 * hvcs_structs_lock and hvcs_pi_lock since these are not touched in an int
  95 * handler.  Initialized hvcs_structs_lock and hvcs_pi_lock to
  96 * SPIN_LOCK_UNLOCKED at declaration time rather than in hvcs_module_init().
  97 * Added spin_lock around list_del() in destroy_hvcs_struct() to protect the
  98 * list traversals from a deletion.  Removed '= NULL' from pointer declaration
  99 * statements since they are initialized NULL by default.  Removed wmb()
 100 * instances from hvcs_try_write().  They probably aren't needed with locking in
 101 * place.  Added check and cleanup for hvcs_pi_buff = kmalloc() in
 102 * hvcs_module_init().  Exposed hvcs_struct.index via a sysfs attribute so that
 103 * the coupling between /dev/hvcs* and a vty-server can be automatically
 104 * determined.  Moved kobject_put() in hvcs_open outside of the
 105 * spin_unlock_irqrestore().
 106 *
 107 * 1.3.1 -> 1.3.2 Changed method for determining hvcs_struct->index and had it
 108 * align with how the tty layer always assigns the lowest index available.  This
 109 * change resulted in a list of ints that denotes which indexes are available.
 110 * Device additions and removals use the new hvcs_get_index() and
 111 * hvcs_return_index() helper functions.  The list is created with
 112 * hvsc_alloc_index_list() and it is destroyed with hvcs_free_index_list().
 113 * Without these fixes hotplug vty-server adapter support goes crazy with this
 114 * driver if the user removes a vty-server adapter.  Moved free_irq() outside of
 115 * the hvcs_final_close() function in order to get it out of the spinlock.
 116 * Rearranged hvcs_close().  Cleaned up some printks and did some housekeeping
 117 * on the changelog.  Removed local CLC_LENGTH and used HVCS_CLC_LENGTH from
 118 * arch/powerepc/include/asm/hvcserver.h
 119 *
 120 * 1.3.2 -> 1.3.3 Replaced yield() in hvcs_close() with tty_wait_until_sent() to
 121 * prevent possible lockup with realtime scheduling as similarly pointed out by
 122 * akpm in hvc_console.  Changed resulted in the removal of hvcs_final_close()
 123 * to reorder cleanup operations and prevent discarding of pending data during
 124 * an hvcs_close().  Removed spinlock protection of hvcs_struct data members in
 125 * hvcs_write_room() and hvcs_chars_in_buffer() because they aren't needed.
 126 */
 127
 128#define HVCS_DRIVER_VERSION "1.3.3"
 129
 130MODULE_AUTHOR("Ryan S. Arnold <rsa@us.ibm.com>");
 131MODULE_DESCRIPTION("IBM hvcs (Hypervisor Virtual Console Server) Driver");
 132MODULE_LICENSE("GPL");
 133MODULE_VERSION(HVCS_DRIVER_VERSION);
 134
 135/*
 136 * Wait this long per iteration while trying to push buffered data to the
 137 * hypervisor before allowing the tty to complete a close operation.
 138 */
 139#define HVCS_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
 140
 141/*
 142 * Since the Linux TTY code does not currently (2-04-2004) support dynamic
 143 * addition of tty derived devices and we shouldn't allocate thousands of
 144 * tty_device pointers when the number of vty-server & vty partner connections
 145 * will most often be much lower than this, we'll arbitrarily allocate
 146 * HVCS_DEFAULT_SERVER_ADAPTERS tty_structs and cdev's by default when we
 147 * register the tty_driver. This can be overridden using an insmod parameter.
 148 */
 149#define HVCS_DEFAULT_SERVER_ADAPTERS	64
 150
 151/*
 152 * The user can't insmod with more than HVCS_MAX_SERVER_ADAPTERS hvcs device
 153 * nodes as a sanity check.  Theoretically there can be over 1 Billion
 154 * vty-server & vty partner connections.
 155 */
 156#define HVCS_MAX_SERVER_ADAPTERS	1024
 157
 158/*
 159 * We let Linux assign us a major number and we start the minors at zero.  There
 160 * is no intuitive mapping between minor number and the target vty-server
 161 * adapter except that each new vty-server adapter is always assigned to the
 162 * smallest minor number available.
 163 */
 164#define HVCS_MINOR_START	0
 165
 166/*
 167 * The hcall interface involves putting 8 chars into each of two registers.
 168 * We load up those 2 registers (in arch/powerpc/platforms/pseries/hvconsole.c)
 169 * by casting char[16] to long[2].  It would work without __ALIGNED__, but a 
 170 * little (tiny) bit slower because an unaligned load is slower than aligned 
 171 * load.
 172 */
 173#define __ALIGNED__	__attribute__((__aligned__(8)))
 174
 175/*
 176 * How much data can firmware send with each hvc_put_chars()?  Maybe this
 177 * should be moved into an architecture specific area.
 178 */
 179#define HVCS_BUFF_LEN	16
 180
 181/*
 182 * This is the maximum amount of data we'll let the user send us (hvcs_write) at
 183 * once in a chunk as a sanity check.
 184 */
 185#define HVCS_MAX_FROM_USER	4096
 186
 187/*
 188 * Be careful when adding flags to this line discipline.  Don't add anything
 189 * that will cause echoing or we'll go into recursive loop echoing chars back
 190 * and forth with the console drivers.
 191 */
 192static struct ktermios hvcs_tty_termios = {
 193	.c_iflag = IGNBRK | IGNPAR,
 194	.c_oflag = OPOST,
 195	.c_cflag = B38400 | CS8 | CREAD | HUPCL,
 196	.c_cc = INIT_C_CC,
 197	.c_ispeed = 38400,
 198	.c_ospeed = 38400
 199};
 200
 201/*
 202 * This value is used to take the place of a command line parameter when the
 203 * module is inserted.  It starts as -1 and stays as such if the user doesn't
 204 * specify a module insmod parameter.  If they DO specify one then it is set to
 205 * the value of the integer passed in.
 206 */
 207static int hvcs_parm_num_devs = -1;
 208module_param(hvcs_parm_num_devs, int, 0);
 209
 210static const char hvcs_driver_name[] = "hvcs";
 211static const char hvcs_device_node[] = "hvcs";
 212static const char hvcs_driver_string[]
 213	= "IBM hvcs (Hypervisor Virtual Console Server) Driver";
 214
 215/* Status of partner info rescan triggered via sysfs. */
 216static int hvcs_rescan_status;
 217
 218static struct tty_driver *hvcs_tty_driver;
 219
 220/*
 221 * In order to be somewhat sane this driver always associates the hvcs_struct
 222 * index element with the numerically equal tty->index.  This means that a
 223 * hotplugged vty-server adapter will always map to the lowest index valued
 224 * device node.  If vty-servers were hotplug removed from the system and then
 225 * new ones added the new vty-server may have the largest slot number of all
 226 * the vty-server adapters in the partition but it may have the lowest dev node
 227 * index of all the adapters due to the hole left by the hotplug removed
 228 * adapter.  There are a set of functions provided to get the lowest index for
 229 * a new device as well as return the index to the list.  This list is allocated
 230 * with a number of elements equal to the number of device nodes requested when
 231 * the module was inserted.
 232 */
 233static int *hvcs_index_list;
 234
 235/*
 236 * How large is the list?  This is kept for traversal since the list is
 237 * dynamically created.
 238 */
 239static int hvcs_index_count;
 240
 241/*
 242 * Used by the khvcsd to pick up I/O operations when the kernel_thread is
 243 * already awake but potentially shifted to TASK_INTERRUPTIBLE state.
 244 */
 245static int hvcs_kicked;
 246
 247/*
 248 * Use by the kthread construct for task operations like waking the sleeping
 249 * thread and stopping the kthread.
 250 */
 251static struct task_struct *hvcs_task;
 252
 253/*
 254 * We allocate this for the use of all of the hvcs_structs when they fetch
 255 * partner info.
 256 */
 257static unsigned long *hvcs_pi_buff;
 258
 259/* Only allow one hvcs_struct to use the hvcs_pi_buff at a time. */
 260static DEFINE_SPINLOCK(hvcs_pi_lock);
 261
 262/* One vty-server per hvcs_struct */
 263struct hvcs_struct {
 
 264	spinlock_t lock;
 265
 266	/*
 267	 * This index identifies this hvcs device as the complement to a
 268	 * specific tty index.
 269	 */
 270	unsigned int index;
 271
 272	struct tty_struct *tty;
 273	int open_count;
 274
 275	/*
 276	 * Used to tell the driver kernel_thread what operations need to take
 277	 * place upon this hvcs_struct instance.
 278	 */
 279	int todo_mask;
 280
 281	/*
 282	 * This buffer is required so that when hvcs_write_room() reports that
 283	 * it can send HVCS_BUFF_LEN characters that it will buffer the full
 284	 * HVCS_BUFF_LEN characters if need be.  This is essential for opost
 285	 * writes since they do not do high level buffering and expect to be
 286	 * able to send what the driver commits to sending buffering
 287	 * [e.g. tab to space conversions in n_tty.c opost()].
 288	 */
 289	char buffer[HVCS_BUFF_LEN];
 290	int chars_in_buffer;
 291
 292	/*
 293	 * Any variable below the kref is valid before a tty is connected and
 294	 * stays valid after the tty is disconnected.  These shouldn't be
 295	 * whacked until the kobject refcount reaches zero though some entries
 296	 * may be changed via sysfs initiatives.
 297	 */
 298	struct kref kref; /* ref count & hvcs_struct lifetime */
 299	int connected; /* is the vty-server currently connected to a vty? */
 300	uint32_t p_unit_address; /* partner unit address */
 301	uint32_t p_partition_ID; /* partner partition ID */
 302	char p_location_code[HVCS_CLC_LENGTH + 1]; /* CLC + Null Term */
 303	struct list_head next; /* list management */
 304	struct vio_dev *vdev;
 305};
 306
 307/* Required to back map a kref to its containing object */
 308#define from_kref(k) container_of(k, struct hvcs_struct, kref)
 309
 310static LIST_HEAD(hvcs_structs);
 311static DEFINE_SPINLOCK(hvcs_structs_lock);
 312static DEFINE_MUTEX(hvcs_init_mutex);
 313
 314static void hvcs_unthrottle(struct tty_struct *tty);
 315static void hvcs_throttle(struct tty_struct *tty);
 316static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance);
 317
 318static int hvcs_write(struct tty_struct *tty,
 319		const unsigned char *buf, int count);
 320static int hvcs_write_room(struct tty_struct *tty);
 321static int hvcs_chars_in_buffer(struct tty_struct *tty);
 322
 323static int hvcs_has_pi(struct hvcs_struct *hvcsd);
 324static void hvcs_set_pi(struct hvcs_partner_info *pi,
 325		struct hvcs_struct *hvcsd);
 326static int hvcs_get_pi(struct hvcs_struct *hvcsd);
 327static int hvcs_rescan_devices_list(void);
 328
 329static int hvcs_partner_connect(struct hvcs_struct *hvcsd);
 330static void hvcs_partner_free(struct hvcs_struct *hvcsd);
 331
 332static int hvcs_enable_device(struct hvcs_struct *hvcsd,
 333		uint32_t unit_address, unsigned int irq, struct vio_dev *dev);
 334
 335static int hvcs_open(struct tty_struct *tty, struct file *filp);
 336static void hvcs_close(struct tty_struct *tty, struct file *filp);
 337static void hvcs_hangup(struct tty_struct * tty);
 338
 339static int __devinit hvcs_probe(struct vio_dev *dev,
 340		const struct vio_device_id *id);
 341static int __devexit hvcs_remove(struct vio_dev *dev);
 342static int __init hvcs_module_init(void);
 343static void __exit hvcs_module_exit(void);
 344static int __devinit hvcs_initialize(void);
 345
 346#define HVCS_SCHED_READ	0x00000001
 347#define HVCS_QUICK_READ	0x00000002
 348#define HVCS_TRY_WRITE	0x00000004
 349#define HVCS_READ_MASK	(HVCS_SCHED_READ | HVCS_QUICK_READ)
 350
 351static inline struct hvcs_struct *from_vio_dev(struct vio_dev *viod)
 352{
 353	return dev_get_drvdata(&viod->dev);
 354}
 355/* The sysfs interface for the driver and devices */
 356
 357static ssize_t hvcs_partner_vtys_show(struct device *dev, struct device_attribute *attr, char *buf)
 358{
 359	struct vio_dev *viod = to_vio_dev(dev);
 360	struct hvcs_struct *hvcsd = from_vio_dev(viod);
 361	unsigned long flags;
 362	int retval;
 363
 364	spin_lock_irqsave(&hvcsd->lock, flags);
 365	retval = sprintf(buf, "%X\n", hvcsd->p_unit_address);
 366	spin_unlock_irqrestore(&hvcsd->lock, flags);
 367	return retval;
 368}
 369static DEVICE_ATTR(partner_vtys, S_IRUGO, hvcs_partner_vtys_show, NULL);
 370
 371static ssize_t hvcs_partner_clcs_show(struct device *dev, struct device_attribute *attr, char *buf)
 372{
 373	struct vio_dev *viod = to_vio_dev(dev);
 374	struct hvcs_struct *hvcsd = from_vio_dev(viod);
 375	unsigned long flags;
 376	int retval;
 377
 378	spin_lock_irqsave(&hvcsd->lock, flags);
 379	retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
 380	spin_unlock_irqrestore(&hvcsd->lock, flags);
 381	return retval;
 382}
 383static DEVICE_ATTR(partner_clcs, S_IRUGO, hvcs_partner_clcs_show, NULL);
 384
 385static ssize_t hvcs_current_vty_store(struct device *dev, struct device_attribute *attr, const char * buf,
 386		size_t count)
 387{
 388	/*
 389	 * Don't need this feature at the present time because firmware doesn't
 390	 * yet support multiple partners.
 391	 */
 392	printk(KERN_INFO "HVCS: Denied current_vty change: -EPERM.\n");
 393	return -EPERM;
 394}
 395
 396static ssize_t hvcs_current_vty_show(struct device *dev, struct device_attribute *attr, char *buf)
 397{
 398	struct vio_dev *viod = to_vio_dev(dev);
 399	struct hvcs_struct *hvcsd = from_vio_dev(viod);
 400	unsigned long flags;
 401	int retval;
 402
 403	spin_lock_irqsave(&hvcsd->lock, flags);
 404	retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
 405	spin_unlock_irqrestore(&hvcsd->lock, flags);
 406	return retval;
 407}
 408
 409static DEVICE_ATTR(current_vty,
 410	S_IRUGO | S_IWUSR, hvcs_current_vty_show, hvcs_current_vty_store);
 411
 412static ssize_t hvcs_vterm_state_store(struct device *dev, struct device_attribute *attr, const char *buf,
 413		size_t count)
 414{
 415	struct vio_dev *viod = to_vio_dev(dev);
 416	struct hvcs_struct *hvcsd = from_vio_dev(viod);
 417	unsigned long flags;
 418
 419	/* writing a '0' to this sysfs entry will result in the disconnect. */
 420	if (simple_strtol(buf, NULL, 0) != 0)
 421		return -EINVAL;
 422
 423	spin_lock_irqsave(&hvcsd->lock, flags);
 424
 425	if (hvcsd->open_count > 0) {
 426		spin_unlock_irqrestore(&hvcsd->lock, flags);
 427		printk(KERN_INFO "HVCS: vterm state unchanged.  "
 428				"The hvcs device node is still in use.\n");
 429		return -EPERM;
 430	}
 431
 432	if (hvcsd->connected == 0) {
 433		spin_unlock_irqrestore(&hvcsd->lock, flags);
 434		printk(KERN_INFO "HVCS: vterm state unchanged. The"
 435				" vty-server is not connected to a vty.\n");
 436		return -EPERM;
 437	}
 438
 439	hvcs_partner_free(hvcsd);
 440	printk(KERN_INFO "HVCS: Closed vty-server@%X and"
 441			" partner vty@%X:%d connection.\n",
 442			hvcsd->vdev->unit_address,
 443			hvcsd->p_unit_address,
 444			(uint32_t)hvcsd->p_partition_ID);
 445
 446	spin_unlock_irqrestore(&hvcsd->lock, flags);
 447	return count;
 448}
 449
 450static ssize_t hvcs_vterm_state_show(struct device *dev, struct device_attribute *attr, char *buf)
 451{
 452	struct vio_dev *viod = to_vio_dev(dev);
 453	struct hvcs_struct *hvcsd = from_vio_dev(viod);
 454	unsigned long flags;
 455	int retval;
 456
 457	spin_lock_irqsave(&hvcsd->lock, flags);
 458	retval = sprintf(buf, "%d\n", hvcsd->connected);
 459	spin_unlock_irqrestore(&hvcsd->lock, flags);
 460	return retval;
 461}
 462static DEVICE_ATTR(vterm_state, S_IRUGO | S_IWUSR,
 463		hvcs_vterm_state_show, hvcs_vterm_state_store);
 464
 465static ssize_t hvcs_index_show(struct device *dev, struct device_attribute *attr, char *buf)
 466{
 467	struct vio_dev *viod = to_vio_dev(dev);
 468	struct hvcs_struct *hvcsd = from_vio_dev(viod);
 469	unsigned long flags;
 470	int retval;
 471
 472	spin_lock_irqsave(&hvcsd->lock, flags);
 473	retval = sprintf(buf, "%d\n", hvcsd->index);
 474	spin_unlock_irqrestore(&hvcsd->lock, flags);
 475	return retval;
 476}
 477
 478static DEVICE_ATTR(index, S_IRUGO, hvcs_index_show, NULL);
 479
 480static struct attribute *hvcs_attrs[] = {
 481	&dev_attr_partner_vtys.attr,
 482	&dev_attr_partner_clcs.attr,
 483	&dev_attr_current_vty.attr,
 484	&dev_attr_vterm_state.attr,
 485	&dev_attr_index.attr,
 486	NULL,
 487};
 488
 489static struct attribute_group hvcs_attr_group = {
 490	.attrs = hvcs_attrs,
 491};
 492
 493static ssize_t hvcs_rescan_show(struct device_driver *ddp, char *buf)
 494{
 495	/* A 1 means it is updating, a 0 means it is done updating */
 496	return snprintf(buf, PAGE_SIZE, "%d\n", hvcs_rescan_status);
 497}
 498
 499static ssize_t hvcs_rescan_store(struct device_driver *ddp, const char * buf,
 500		size_t count)
 501{
 502	if ((simple_strtol(buf, NULL, 0) != 1)
 503		&& (hvcs_rescan_status != 0))
 504		return -EINVAL;
 505
 506	hvcs_rescan_status = 1;
 507	printk(KERN_INFO "HVCS: rescanning partner info for all"
 508		" vty-servers.\n");
 509	hvcs_rescan_devices_list();
 510	hvcs_rescan_status = 0;
 511	return count;
 512}
 513
 514static DRIVER_ATTR(rescan,
 515	S_IRUGO | S_IWUSR, hvcs_rescan_show, hvcs_rescan_store);
 516
 517static void hvcs_kick(void)
 518{
 519	hvcs_kicked = 1;
 520	wmb();
 521	wake_up_process(hvcs_task);
 522}
 523
 524static void hvcs_unthrottle(struct tty_struct *tty)
 525{
 526	struct hvcs_struct *hvcsd = tty->driver_data;
 527	unsigned long flags;
 528
 529	spin_lock_irqsave(&hvcsd->lock, flags);
 530	hvcsd->todo_mask |= HVCS_SCHED_READ;
 531	spin_unlock_irqrestore(&hvcsd->lock, flags);
 532	hvcs_kick();
 533}
 534
 535static void hvcs_throttle(struct tty_struct *tty)
 536{
 537	struct hvcs_struct *hvcsd = tty->driver_data;
 538	unsigned long flags;
 539
 540	spin_lock_irqsave(&hvcsd->lock, flags);
 541	vio_disable_interrupts(hvcsd->vdev);
 542	spin_unlock_irqrestore(&hvcsd->lock, flags);
 543}
 544
 545/*
 546 * If the device is being removed we don't have to worry about this interrupt
 547 * handler taking any further interrupts because they are disabled which means
 548 * the hvcs_struct will always be valid in this handler.
 549 */
 550static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance)
 551{
 552	struct hvcs_struct *hvcsd = dev_instance;
 553
 554	spin_lock(&hvcsd->lock);
 555	vio_disable_interrupts(hvcsd->vdev);
 556	hvcsd->todo_mask |= HVCS_SCHED_READ;
 557	spin_unlock(&hvcsd->lock);
 558	hvcs_kick();
 559
 560	return IRQ_HANDLED;
 561}
 562
 563/* This function must be called with the hvcsd->lock held */
 564static void hvcs_try_write(struct hvcs_struct *hvcsd)
 565{
 566	uint32_t unit_address = hvcsd->vdev->unit_address;
 567	struct tty_struct *tty = hvcsd->tty;
 568	int sent;
 569
 570	if (hvcsd->todo_mask & HVCS_TRY_WRITE) {
 571		/* won't send partial writes */
 572		sent = hvc_put_chars(unit_address,
 573				&hvcsd->buffer[0],
 574				hvcsd->chars_in_buffer );
 575		if (sent > 0) {
 576			hvcsd->chars_in_buffer = 0;
 577			/* wmb(); */
 578			hvcsd->todo_mask &= ~(HVCS_TRY_WRITE);
 579			/* wmb(); */
 580
 581			/*
 582			 * We are still obligated to deliver the data to the
 583			 * hypervisor even if the tty has been closed because
 584			 * we committed to delivering it.  But don't try to wake
 585			 * a non-existent tty.
 586			 */
 587			if (tty) {
 588				tty_wakeup(tty);
 589			}
 590		}
 591	}
 592}
 593
 594static int hvcs_io(struct hvcs_struct *hvcsd)
 595{
 596	uint32_t unit_address;
 597	struct tty_struct *tty;
 598	char buf[HVCS_BUFF_LEN] __ALIGNED__;
 599	unsigned long flags;
 600	int got = 0;
 601
 602	spin_lock_irqsave(&hvcsd->lock, flags);
 603
 604	unit_address = hvcsd->vdev->unit_address;
 605	tty = hvcsd->tty;
 606
 607	hvcs_try_write(hvcsd);
 608
 609	if (!tty || test_bit(TTY_THROTTLED, &tty->flags)) {
 610		hvcsd->todo_mask &= ~(HVCS_READ_MASK);
 611		goto bail;
 612	} else if (!(hvcsd->todo_mask & (HVCS_READ_MASK)))
 613		goto bail;
 614
 615	/* remove the read masks */
 616	hvcsd->todo_mask &= ~(HVCS_READ_MASK);
 617
 618	if (tty_buffer_request_room(tty, HVCS_BUFF_LEN) >= HVCS_BUFF_LEN) {
 619		got = hvc_get_chars(unit_address,
 620				&buf[0],
 621				HVCS_BUFF_LEN);
 622		tty_insert_flip_string(tty, buf, got);
 623	}
 624
 625	/* Give the TTY time to process the data we just sent. */
 626	if (got)
 627		hvcsd->todo_mask |= HVCS_QUICK_READ;
 628
 629	spin_unlock_irqrestore(&hvcsd->lock, flags);
 630	/* This is synch because tty->low_latency == 1 */
 631	if(got)
 632		tty_flip_buffer_push(tty);
 633
 634	if (!got) {
 635		/* Do this _after_ the flip_buffer_push */
 636		spin_lock_irqsave(&hvcsd->lock, flags);
 637		vio_enable_interrupts(hvcsd->vdev);
 638		spin_unlock_irqrestore(&hvcsd->lock, flags);
 639	}
 640
 641	return hvcsd->todo_mask;
 642
 643 bail:
 644	spin_unlock_irqrestore(&hvcsd->lock, flags);
 645	return hvcsd->todo_mask;
 646}
 647
 648static int khvcsd(void *unused)
 649{
 650	struct hvcs_struct *hvcsd;
 651	int hvcs_todo_mask;
 652
 653	__set_current_state(TASK_RUNNING);
 654
 655	do {
 656		hvcs_todo_mask = 0;
 657		hvcs_kicked = 0;
 658		wmb();
 659
 660		spin_lock(&hvcs_structs_lock);
 661		list_for_each_entry(hvcsd, &hvcs_structs, next) {
 662			hvcs_todo_mask |= hvcs_io(hvcsd);
 663		}
 664		spin_unlock(&hvcs_structs_lock);
 665
 666		/*
 667		 * If any of the hvcs adapters want to try a write or quick read
 668		 * don't schedule(), yield a smidgen then execute the hvcs_io
 669		 * thread again for those that want the write.
 670		 */
 671		 if (hvcs_todo_mask & (HVCS_TRY_WRITE | HVCS_QUICK_READ)) {
 672			yield();
 673			continue;
 674		}
 675
 676		set_current_state(TASK_INTERRUPTIBLE);
 677		if (!hvcs_kicked)
 678			schedule();
 679		__set_current_state(TASK_RUNNING);
 680	} while (!kthread_should_stop());
 681
 682	return 0;
 683}
 684
 685static struct vio_device_id hvcs_driver_table[] __devinitdata= {
 686	{"serial-server", "hvterm2"},
 687	{ "", "" }
 688};
 689MODULE_DEVICE_TABLE(vio, hvcs_driver_table);
 690
 691static void hvcs_return_index(int index)
 692{
 693	/* Paranoia check */
 694	if (!hvcs_index_list)
 695		return;
 696	if (index < 0 || index >= hvcs_index_count)
 697		return;
 698	if (hvcs_index_list[index] == -1)
 699		return;
 700	else
 701		hvcs_index_list[index] = -1;
 702}
 703
 704/* callback when the kref ref count reaches zero */
 705static void destroy_hvcs_struct(struct kref *kref)
 706{
 707	struct hvcs_struct *hvcsd = from_kref(kref);
 708	struct vio_dev *vdev;
 709	unsigned long flags;
 710
 711	spin_lock(&hvcs_structs_lock);
 712	spin_lock_irqsave(&hvcsd->lock, flags);
 713
 714	/* the list_del poisons the pointers */
 715	list_del(&(hvcsd->next));
 716
 717	if (hvcsd->connected == 1) {
 718		hvcs_partner_free(hvcsd);
 719		printk(KERN_INFO "HVCS: Closed vty-server@%X and"
 720				" partner vty@%X:%d connection.\n",
 721				hvcsd->vdev->unit_address,
 722				hvcsd->p_unit_address,
 723				(uint32_t)hvcsd->p_partition_ID);
 724	}
 725	printk(KERN_INFO "HVCS: Destroyed hvcs_struct for vty-server@%X.\n",
 726			hvcsd->vdev->unit_address);
 727
 728	vdev = hvcsd->vdev;
 729	hvcsd->vdev = NULL;
 730
 731	hvcsd->p_unit_address = 0;
 732	hvcsd->p_partition_ID = 0;
 733	hvcs_return_index(hvcsd->index);
 734	memset(&hvcsd->p_location_code[0], 0x00, HVCS_CLC_LENGTH + 1);
 735
 736	spin_unlock_irqrestore(&hvcsd->lock, flags);
 737	spin_unlock(&hvcs_structs_lock);
 738
 739	sysfs_remove_group(&vdev->dev.kobj, &hvcs_attr_group);
 740
 741	kfree(hvcsd);
 742}
 743
 
 
 
 
 744static int hvcs_get_index(void)
 745{
 746	int i;
 747	/* Paranoia check */
 748	if (!hvcs_index_list) {
 749		printk(KERN_ERR "HVCS: hvcs_index_list NOT valid!.\n");
 750		return -EFAULT;
 751	}
 752	/* Find the numerically lowest first free index. */
 753	for(i = 0; i < hvcs_index_count; i++) {
 754		if (hvcs_index_list[i] == -1) {
 755			hvcs_index_list[i] = 0;
 756			return i;
 757		}
 758	}
 759	return -1;
 760}
 761
 762static int __devinit hvcs_probe(
 763	struct vio_dev *dev,
 764	const struct vio_device_id *id)
 765{
 766	struct hvcs_struct *hvcsd;
 767	int index, rc;
 768	int retval;
 769
 770	if (!dev || !id) {
 771		printk(KERN_ERR "HVCS: probed with invalid parameter.\n");
 772		return -EPERM;
 773	}
 774
 775	/* Make sure we are properly initialized */
 776	rc = hvcs_initialize();
 777	if (rc) {
 778		pr_err("HVCS: Failed to initialize core driver.\n");
 779		return rc;
 780	}
 781
 782	/* early to avoid cleanup on failure */
 783	index = hvcs_get_index();
 784	if (index < 0) {
 785		return -EFAULT;
 786	}
 787
 788	hvcsd = kzalloc(sizeof(*hvcsd), GFP_KERNEL);
 789	if (!hvcsd)
 790		return -ENODEV;
 791
 792
 
 793	spin_lock_init(&hvcsd->lock);
 794	/* Automatically incs the refcount the first time */
 795	kref_init(&hvcsd->kref);
 796
 797	hvcsd->vdev = dev;
 798	dev_set_drvdata(&dev->dev, hvcsd);
 799
 800	hvcsd->index = index;
 801
 802	/* hvcsd->index = ++hvcs_struct_count; */
 803	hvcsd->chars_in_buffer = 0;
 804	hvcsd->todo_mask = 0;
 805	hvcsd->connected = 0;
 806
 807	/*
 808	 * This will populate the hvcs_struct's partner info fields for the
 809	 * first time.
 810	 */
 811	if (hvcs_get_pi(hvcsd)) {
 812		printk(KERN_ERR "HVCS: Failed to fetch partner"
 813			" info for vty-server@%X on device probe.\n",
 814			hvcsd->vdev->unit_address);
 815	}
 816
 817	/*
 818	 * If a user app opens a tty that corresponds to this vty-server before
 819	 * the hvcs_struct has been added to the devices list then the user app
 820	 * will get -ENODEV.
 821	 */
 822	spin_lock(&hvcs_structs_lock);
 823	list_add_tail(&(hvcsd->next), &hvcs_structs);
 824	spin_unlock(&hvcs_structs_lock);
 825
 826	retval = sysfs_create_group(&dev->dev.kobj, &hvcs_attr_group);
 827	if (retval) {
 828		printk(KERN_ERR "HVCS: Can't create sysfs attrs for vty-server@%X\n",
 829		       hvcsd->vdev->unit_address);
 830		return retval;
 831	}
 832
 833	printk(KERN_INFO "HVCS: vty-server@%X added to the vio bus.\n", dev->unit_address);
 834
 835	/*
 836	 * DON'T enable interrupts here because there is no user to receive the
 837	 * data.
 838	 */
 839	return 0;
 840}
 841
 842static int __devexit hvcs_remove(struct vio_dev *dev)
 843{
 844	struct hvcs_struct *hvcsd = dev_get_drvdata(&dev->dev);
 845	unsigned long flags;
 846	struct tty_struct *tty;
 847
 848	if (!hvcsd)
 849		return -ENODEV;
 850
 851	/* By this time the vty-server won't be getting any more interrupts */
 852
 853	spin_lock_irqsave(&hvcsd->lock, flags);
 854
 855	tty = hvcsd->tty;
 856
 857	spin_unlock_irqrestore(&hvcsd->lock, flags);
 858
 859	/*
 860	 * Let the last holder of this object cause it to be removed, which
 861	 * would probably be tty_hangup below.
 862	 */
 863	kref_put(&hvcsd->kref, destroy_hvcs_struct);
 864
 865	/*
 866	 * The hangup is a scheduled function which will auto chain call
 867	 * hvcs_hangup.  The tty should always be valid at this time unless a
 868	 * simultaneous tty close already cleaned up the hvcs_struct.
 869	 */
 870	if (tty)
 871		tty_hangup(tty);
 872
 873	printk(KERN_INFO "HVCS: vty-server@%X removed from the"
 874			" vio bus.\n", dev->unit_address);
 875	return 0;
 876};
 877
 878static struct vio_driver hvcs_vio_driver = {
 879	.id_table	= hvcs_driver_table,
 880	.probe		= hvcs_probe,
 881	.remove		= __devexit_p(hvcs_remove),
 882	.driver		= {
 883		.name	= hvcs_driver_name,
 884		.owner	= THIS_MODULE,
 885	}
 886};
 887
 888/* Only called from hvcs_get_pi please */
 889static void hvcs_set_pi(struct hvcs_partner_info *pi, struct hvcs_struct *hvcsd)
 890{
 891	int clclength;
 892
 893	hvcsd->p_unit_address = pi->unit_address;
 894	hvcsd->p_partition_ID  = pi->partition_ID;
 895	clclength = strlen(&pi->location_code[0]);
 896	if (clclength > HVCS_CLC_LENGTH)
 897		clclength = HVCS_CLC_LENGTH;
 898
 899	/* copy the null-term char too */
 900	strncpy(&hvcsd->p_location_code[0],
 901			&pi->location_code[0], clclength + 1);
 902}
 903
 904/*
 905 * Traverse the list and add the partner info that is found to the hvcs_struct
 906 * struct entry. NOTE: At this time I know that partner info will return a
 907 * single entry but in the future there may be multiple partner info entries per
 908 * vty-server and you'll want to zero out that list and reset it.  If for some
 909 * reason you have an old version of this driver but there IS more than one
 910 * partner info then hvcsd->p_* will hold the last partner info data from the
 911 * firmware query.  A good way to update this code would be to replace the three
 912 * partner info fields in hvcs_struct with a list of hvcs_partner_info
 913 * instances.
 914 *
 915 * This function must be called with the hvcsd->lock held.
 916 */
 917static int hvcs_get_pi(struct hvcs_struct *hvcsd)
 918{
 919	struct hvcs_partner_info *pi;
 920	uint32_t unit_address = hvcsd->vdev->unit_address;
 921	struct list_head head;
 922	int retval;
 923
 924	spin_lock(&hvcs_pi_lock);
 925	if (!hvcs_pi_buff) {
 926		spin_unlock(&hvcs_pi_lock);
 927		return -EFAULT;
 928	}
 929	retval = hvcs_get_partner_info(unit_address, &head, hvcs_pi_buff);
 930	spin_unlock(&hvcs_pi_lock);
 931	if (retval) {
 932		printk(KERN_ERR "HVCS: Failed to fetch partner"
 933			" info for vty-server@%x.\n", unit_address);
 934		return retval;
 935	}
 936
 937	/* nixes the values if the partner vty went away */
 938	hvcsd->p_unit_address = 0;
 939	hvcsd->p_partition_ID = 0;
 940
 941	list_for_each_entry(pi, &head, node)
 942		hvcs_set_pi(pi, hvcsd);
 943
 944	hvcs_free_partner_info(&head);
 945	return 0;
 946}
 947
 948/*
 949 * This function is executed by the driver "rescan" sysfs entry.  It shouldn't
 950 * be executed elsewhere, in order to prevent deadlock issues.
 951 */
 952static int hvcs_rescan_devices_list(void)
 953{
 954	struct hvcs_struct *hvcsd;
 955	unsigned long flags;
 956
 957	spin_lock(&hvcs_structs_lock);
 958
 959	list_for_each_entry(hvcsd, &hvcs_structs, next) {
 960		spin_lock_irqsave(&hvcsd->lock, flags);
 961		hvcs_get_pi(hvcsd);
 962		spin_unlock_irqrestore(&hvcsd->lock, flags);
 963	}
 964
 965	spin_unlock(&hvcs_structs_lock);
 966
 967	return 0;
 968}
 969
 970/*
 971 * Farm this off into its own function because it could be more complex once
 972 * multiple partners support is added. This function should be called with
 973 * the hvcsd->lock held.
 974 */
 975static int hvcs_has_pi(struct hvcs_struct *hvcsd)
 976{
 977	if ((!hvcsd->p_unit_address) || (!hvcsd->p_partition_ID))
 978		return 0;
 979	return 1;
 980}
 981
 982/*
 983 * NOTE: It is possible that the super admin removed a partner vty and then
 984 * added a different vty as the new partner.
 985 *
 986 * This function must be called with the hvcsd->lock held.
 987 */
 988static int hvcs_partner_connect(struct hvcs_struct *hvcsd)
 989{
 990	int retval;
 991	unsigned int unit_address = hvcsd->vdev->unit_address;
 992
 993	/*
 994	 * If there wasn't any pi when the device was added it doesn't meant
 995	 * there isn't any now.  This driver isn't notified when a new partner
 996	 * vty is added to a vty-server so we discover changes on our own.
 997	 * Please see comments in hvcs_register_connection() for justification
 998	 * of this bizarre code.
 999	 */
1000	retval = hvcs_register_connection(unit_address,
1001			hvcsd->p_partition_ID,
1002			hvcsd->p_unit_address);
1003	if (!retval) {
1004		hvcsd->connected = 1;
1005		return 0;
1006	} else if (retval != -EINVAL)
1007		return retval;
1008
1009	/*
1010	 * As per the spec re-get the pi and try again if -EINVAL after the
1011	 * first connection attempt.
1012	 */
1013	if (hvcs_get_pi(hvcsd))
1014		return -ENOMEM;
1015
1016	if (!hvcs_has_pi(hvcsd))
1017		return -ENODEV;
1018
1019	retval = hvcs_register_connection(unit_address,
1020			hvcsd->p_partition_ID,
1021			hvcsd->p_unit_address);
1022	if (retval != -EINVAL) {
1023		hvcsd->connected = 1;
1024		return retval;
1025	}
1026
1027	/*
1028	 * EBUSY is the most likely scenario though the vty could have been
1029	 * removed or there really could be an hcall error due to the parameter
1030	 * data but thanks to ambiguous firmware return codes we can't really
1031	 * tell.
1032	 */
1033	printk(KERN_INFO "HVCS: vty-server or partner"
1034			" vty is busy.  Try again later.\n");
1035	return -EBUSY;
1036}
1037
1038/* This function must be called with the hvcsd->lock held */
1039static void hvcs_partner_free(struct hvcs_struct *hvcsd)
1040{
1041	int retval;
1042	do {
1043		retval = hvcs_free_connection(hvcsd->vdev->unit_address);
1044	} while (retval == -EBUSY);
1045	hvcsd->connected = 0;
1046}
1047
1048/* This helper function must be called WITHOUT the hvcsd->lock held */
1049static int hvcs_enable_device(struct hvcs_struct *hvcsd, uint32_t unit_address,
1050		unsigned int irq, struct vio_dev *vdev)
1051{
1052	unsigned long flags;
1053	int rc;
1054
1055	/*
1056	 * It is possible that the vty-server was removed between the time that
1057	 * the conn was registered and now.
1058	 */
1059	if (!(rc = request_irq(irq, &hvcs_handle_interrupt,
1060				IRQF_DISABLED, "ibmhvcs", hvcsd))) {
1061		/*
1062		 * It is possible the vty-server was removed after the irq was
1063		 * requested but before we have time to enable interrupts.
1064		 */
1065		if (vio_enable_interrupts(vdev) == H_SUCCESS)
1066			return 0;
1067		else {
1068			printk(KERN_ERR "HVCS: int enable failed for"
1069					" vty-server@%X.\n", unit_address);
1070			free_irq(irq, hvcsd);
1071		}
1072	} else
1073		printk(KERN_ERR "HVCS: irq req failed for"
1074				" vty-server@%X.\n", unit_address);
1075
1076	spin_lock_irqsave(&hvcsd->lock, flags);
1077	hvcs_partner_free(hvcsd);
1078	spin_unlock_irqrestore(&hvcsd->lock, flags);
1079
1080	return rc;
1081
1082}
1083
1084/*
1085 * This always increments the kref ref count if the call is successful.
1086 * Please remember to dec when you are done with the instance.
1087 *
1088 * NOTICE: Do NOT hold either the hvcs_struct.lock or hvcs_structs_lock when
1089 * calling this function or you will get deadlock.
1090 */
1091static struct hvcs_struct *hvcs_get_by_index(int index)
1092{
1093	struct hvcs_struct *hvcsd = NULL;
1094	unsigned long flags;
1095
1096	spin_lock(&hvcs_structs_lock);
1097	/* We can immediately discard OOB requests */
1098	if (index >= 0 && index < HVCS_MAX_SERVER_ADAPTERS) {
1099		list_for_each_entry(hvcsd, &hvcs_structs, next) {
1100			spin_lock_irqsave(&hvcsd->lock, flags);
1101			if (hvcsd->index == index) {
1102				kref_get(&hvcsd->kref);
1103				spin_unlock_irqrestore(&hvcsd->lock, flags);
1104				spin_unlock(&hvcs_structs_lock);
1105				return hvcsd;
1106			}
1107			spin_unlock_irqrestore(&hvcsd->lock, flags);
 
 
1108		}
1109		hvcsd = NULL;
1110	}
1111
1112	spin_unlock(&hvcs_structs_lock);
1113	return hvcsd;
 
1114}
1115
1116/*
1117 * This is invoked via the tty_open interface when a user app connects to the
1118 * /dev node.
1119 */
1120static int hvcs_open(struct tty_struct *tty, struct file *filp)
1121{
1122	struct hvcs_struct *hvcsd;
1123	int rc, retval = 0;
1124	unsigned long flags;
1125	unsigned int irq;
1126	struct vio_dev *vdev;
1127	unsigned long unit_address;
1128
1129	if (tty->driver_data)
1130		goto fast_open;
1131
1132	/*
1133	 * Is there a vty-server that shares the same index?
1134	 * This function increments the kref index.
1135	 */
1136	if (!(hvcsd = hvcs_get_by_index(tty->index))) {
1137		printk(KERN_WARNING "HVCS: open failed, no device associated"
1138				" with tty->index %d.\n", tty->index);
1139		return -ENODEV;
1140	}
1141
1142	spin_lock_irqsave(&hvcsd->lock, flags);
1143
1144	if (hvcsd->connected == 0)
1145		if ((retval = hvcs_partner_connect(hvcsd)))
1146			goto error_release;
1147
1148	hvcsd->open_count = 1;
1149	hvcsd->tty = tty;
1150	tty->driver_data = hvcsd;
1151
1152	memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1153
1154	/*
1155	 * Save these in the spinlock for the enable operations that need them
1156	 * outside of the spinlock.
1157	 */
1158	irq = hvcsd->vdev->irq;
1159	vdev = hvcsd->vdev;
1160	unit_address = hvcsd->vdev->unit_address;
1161
1162	hvcsd->todo_mask |= HVCS_SCHED_READ;
1163	spin_unlock_irqrestore(&hvcsd->lock, flags);
1164
1165	/*
1166	 * This must be done outside of the spinlock because it requests irqs
1167	 * and will grab the spinlock and free the connection if it fails.
1168	 */
1169	if (((rc = hvcs_enable_device(hvcsd, unit_address, irq, vdev)))) {
1170		kref_put(&hvcsd->kref, destroy_hvcs_struct);
1171		printk(KERN_WARNING "HVCS: enable device failed.\n");
1172		return rc;
1173	}
1174
1175	goto open_success;
1176
1177fast_open:
1178	hvcsd = tty->driver_data;
1179
1180	spin_lock_irqsave(&hvcsd->lock, flags);
1181	kref_get(&hvcsd->kref);
1182	hvcsd->open_count++;
1183	hvcsd->todo_mask |= HVCS_SCHED_READ;
1184	spin_unlock_irqrestore(&hvcsd->lock, flags);
1185
1186open_success:
1187	hvcs_kick();
1188
1189	printk(KERN_INFO "HVCS: vty-server@%X connection opened.\n",
1190		hvcsd->vdev->unit_address );
1191
1192	return 0;
1193
1194error_release:
1195	spin_unlock_irqrestore(&hvcsd->lock, flags);
1196	kref_put(&hvcsd->kref, destroy_hvcs_struct);
1197
1198	printk(KERN_WARNING "HVCS: partner connect failed.\n");
1199	return retval;
1200}
1201
1202static void hvcs_close(struct tty_struct *tty, struct file *filp)
1203{
1204	struct hvcs_struct *hvcsd;
1205	unsigned long flags;
1206	int irq = NO_IRQ;
1207
1208	/*
1209	 * Is someone trying to close the file associated with this device after
1210	 * we have hung up?  If so tty->driver_data wouldn't be valid.
1211	 */
1212	if (tty_hung_up_p(filp))
1213		return;
1214
1215	/*
1216	 * No driver_data means that this close was probably issued after a
1217	 * failed hvcs_open by the tty layer's release_dev() api and we can just
1218	 * exit cleanly.
1219	 */
1220	if (!tty->driver_data)
1221		return;
1222
1223	hvcsd = tty->driver_data;
1224
1225	spin_lock_irqsave(&hvcsd->lock, flags);
1226	if (--hvcsd->open_count == 0) {
1227
1228		vio_disable_interrupts(hvcsd->vdev);
1229
1230		/*
1231		 * NULL this early so that the kernel_thread doesn't try to
1232		 * execute any operations on the TTY even though it is obligated
1233		 * to deliver any pending I/O to the hypervisor.
1234		 */
1235		hvcsd->tty = NULL;
1236
1237		irq = hvcsd->vdev->irq;
1238		spin_unlock_irqrestore(&hvcsd->lock, flags);
1239
1240		tty_wait_until_sent(tty, HVCS_CLOSE_WAIT);
1241
1242		/*
1243		 * This line is important because it tells hvcs_open that this
1244		 * device needs to be re-configured the next time hvcs_open is
1245		 * called.
1246		 */
1247		tty->driver_data = NULL;
1248
1249		free_irq(irq, hvcsd);
1250		kref_put(&hvcsd->kref, destroy_hvcs_struct);
1251		return;
1252	} else if (hvcsd->open_count < 0) {
1253		printk(KERN_ERR "HVCS: vty-server@%X open_count: %d"
1254				" is missmanaged.\n",
1255		hvcsd->vdev->unit_address, hvcsd->open_count);
1256	}
1257
1258	spin_unlock_irqrestore(&hvcsd->lock, flags);
1259	kref_put(&hvcsd->kref, destroy_hvcs_struct);
1260}
1261
1262static void hvcs_hangup(struct tty_struct * tty)
1263{
1264	struct hvcs_struct *hvcsd = tty->driver_data;
1265	unsigned long flags;
1266	int temp_open_count;
1267	int irq = NO_IRQ;
1268
1269	spin_lock_irqsave(&hvcsd->lock, flags);
1270	/* Preserve this so that we know how many kref refs to put */
1271	temp_open_count = hvcsd->open_count;
1272
1273	/*
1274	 * Don't kref put inside the spinlock because the destruction
1275	 * callback may use the spinlock and it may get called before the
1276	 * spinlock has been released.
1277	 */
1278	vio_disable_interrupts(hvcsd->vdev);
1279
1280	hvcsd->todo_mask = 0;
1281
1282	/* I don't think the tty needs the hvcs_struct pointer after a hangup */
1283	hvcsd->tty->driver_data = NULL;
1284	hvcsd->tty = NULL;
1285
1286	hvcsd->open_count = 0;
1287
1288	/* This will drop any buffered data on the floor which is OK in a hangup
1289	 * scenario. */
1290	memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1291	hvcsd->chars_in_buffer = 0;
1292
1293	irq = hvcsd->vdev->irq;
1294
1295	spin_unlock_irqrestore(&hvcsd->lock, flags);
1296
1297	free_irq(irq, hvcsd);
1298
1299	/*
1300	 * We need to kref_put() for every open_count we have since the
1301	 * tty_hangup() function doesn't invoke a close per open connection on a
1302	 * non-console device.
1303	 */
1304	while(temp_open_count) {
1305		--temp_open_count;
1306		/*
1307		 * The final put will trigger destruction of the hvcs_struct.
1308		 * NOTE:  If this hangup was signaled from user space then the
1309		 * final put will never happen.
1310		 */
1311		kref_put(&hvcsd->kref, destroy_hvcs_struct);
1312	}
1313}
1314
1315/*
1316 * NOTE: This is almost always from_user since user level apps interact with the
1317 * /dev nodes. I'm trusting that if hvcs_write gets called and interrupted by
1318 * hvcs_remove (which removes the target device and executes tty_hangup()) that
1319 * tty_hangup will allow hvcs_write time to complete execution before it
1320 * terminates our device.
1321 */
1322static int hvcs_write(struct tty_struct *tty,
1323		const unsigned char *buf, int count)
1324{
1325	struct hvcs_struct *hvcsd = tty->driver_data;
1326	unsigned int unit_address;
1327	const unsigned char *charbuf;
1328	unsigned long flags;
1329	int total_sent = 0;
1330	int tosend = 0;
1331	int result = 0;
1332
1333	/*
1334	 * If they don't check the return code off of their open they may
1335	 * attempt this even if there is no connected device.
1336	 */
1337	if (!hvcsd)
1338		return -ENODEV;
1339
1340	/* Reasonable size to prevent user level flooding */
1341	if (count > HVCS_MAX_FROM_USER) {
1342		printk(KERN_WARNING "HVCS write: count being truncated to"
1343				" HVCS_MAX_FROM_USER.\n");
1344		count = HVCS_MAX_FROM_USER;
1345	}
1346
1347	charbuf = buf;
1348
1349	spin_lock_irqsave(&hvcsd->lock, flags);
1350
1351	/*
1352	 * Somehow an open succeeded but the device was removed or the
1353	 * connection terminated between the vty-server and partner vty during
1354	 * the middle of a write operation?  This is a crummy place to do this
1355	 * but we want to keep it all in the spinlock.
1356	 */
1357	if (hvcsd->open_count <= 0) {
1358		spin_unlock_irqrestore(&hvcsd->lock, flags);
1359		return -ENODEV;
1360	}
1361
1362	unit_address = hvcsd->vdev->unit_address;
1363
1364	while (count > 0) {
1365		tosend = min(count, (HVCS_BUFF_LEN - hvcsd->chars_in_buffer));
1366		/*
1367		 * No more space, this probably means that the last call to
1368		 * hvcs_write() didn't succeed and the buffer was filled up.
1369		 */
1370		if (!tosend)
1371			break;
1372
1373		memcpy(&hvcsd->buffer[hvcsd->chars_in_buffer],
1374				&charbuf[total_sent],
1375				tosend);
1376
1377		hvcsd->chars_in_buffer += tosend;
1378
1379		result = 0;
1380
1381		/*
1382		 * If this is true then we don't want to try writing to the
1383		 * hypervisor because that is the kernel_threads job now.  We'll
1384		 * just add to the buffer.
1385		 */
1386		if (!(hvcsd->todo_mask & HVCS_TRY_WRITE))
1387			/* won't send partial writes */
1388			result = hvc_put_chars(unit_address,
1389					&hvcsd->buffer[0],
1390					hvcsd->chars_in_buffer);
1391
1392		/*
1393		 * Since we know we have enough room in hvcsd->buffer for
1394		 * tosend we record that it was sent regardless of whether the
1395		 * hypervisor actually took it because we have it buffered.
1396		 */
1397		total_sent+=tosend;
1398		count-=tosend;
1399		if (result == 0) {
1400			hvcsd->todo_mask |= HVCS_TRY_WRITE;
1401			hvcs_kick();
1402			break;
1403		}
1404
1405		hvcsd->chars_in_buffer = 0;
1406		/*
1407		 * Test after the chars_in_buffer reset otherwise this could
1408		 * deadlock our writes if hvc_put_chars fails.
1409		 */
1410		if (result < 0)
1411			break;
1412	}
1413
1414	spin_unlock_irqrestore(&hvcsd->lock, flags);
1415
1416	if (result == -1)
1417		return -EIO;
1418	else
1419		return total_sent;
1420}
1421
1422/*
1423 * This is really asking how much can we guarantee that we can send or that we
1424 * absolutely WILL BUFFER if we can't send it.  This driver MUST honor the
1425 * return value, hence the reason for hvcs_struct buffering.
1426 */
1427static int hvcs_write_room(struct tty_struct *tty)
1428{
1429	struct hvcs_struct *hvcsd = tty->driver_data;
1430
1431	if (!hvcsd || hvcsd->open_count <= 0)
1432		return 0;
1433
1434	return HVCS_BUFF_LEN - hvcsd->chars_in_buffer;
1435}
1436
1437static int hvcs_chars_in_buffer(struct tty_struct *tty)
1438{
1439	struct hvcs_struct *hvcsd = tty->driver_data;
1440
1441	return hvcsd->chars_in_buffer;
1442}
1443
1444static const struct tty_operations hvcs_ops = {
1445	.open = hvcs_open,
1446	.close = hvcs_close,
1447	.hangup = hvcs_hangup,
1448	.write = hvcs_write,
1449	.write_room = hvcs_write_room,
1450	.chars_in_buffer = hvcs_chars_in_buffer,
1451	.unthrottle = hvcs_unthrottle,
1452	.throttle = hvcs_throttle,
1453};
1454
1455static int hvcs_alloc_index_list(int n)
1456{
1457	int i;
1458
1459	hvcs_index_list = kmalloc(n * sizeof(hvcs_index_count),GFP_KERNEL);
1460	if (!hvcs_index_list)
1461		return -ENOMEM;
1462	hvcs_index_count = n;
1463	for (i = 0; i < hvcs_index_count; i++)
1464		hvcs_index_list[i] = -1;
1465	return 0;
1466}
1467
1468static void hvcs_free_index_list(void)
1469{
1470	/* Paranoia check to be thorough. */
1471	kfree(hvcs_index_list);
1472	hvcs_index_list = NULL;
1473	hvcs_index_count = 0;
1474}
1475
1476static int __devinit hvcs_initialize(void)
1477{
1478	int rc, num_ttys_to_alloc;
1479
1480	mutex_lock(&hvcs_init_mutex);
1481	if (hvcs_task) {
1482		mutex_unlock(&hvcs_init_mutex);
1483		return 0;
1484	}
1485
1486	/* Has the user specified an overload with an insmod param? */
1487	if (hvcs_parm_num_devs <= 0 ||
1488		(hvcs_parm_num_devs > HVCS_MAX_SERVER_ADAPTERS)) {
1489		num_ttys_to_alloc = HVCS_DEFAULT_SERVER_ADAPTERS;
1490	} else
1491		num_ttys_to_alloc = hvcs_parm_num_devs;
1492
1493	hvcs_tty_driver = alloc_tty_driver(num_ttys_to_alloc);
1494	if (!hvcs_tty_driver)
1495		return -ENOMEM;
1496
1497	if (hvcs_alloc_index_list(num_ttys_to_alloc)) {
1498		rc = -ENOMEM;
1499		goto index_fail;
1500	}
1501
1502	hvcs_tty_driver->owner = THIS_MODULE;
1503
1504	hvcs_tty_driver->driver_name = hvcs_driver_name;
1505	hvcs_tty_driver->name = hvcs_device_node;
1506
1507	/*
1508	 * We'll let the system assign us a major number, indicated by leaving
1509	 * it blank.
1510	 */
1511
1512	hvcs_tty_driver->minor_start = HVCS_MINOR_START;
1513	hvcs_tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
1514
1515	/*
1516	 * We role our own so that we DONT ECHO.  We can't echo because the
1517	 * device we are connecting to already echoes by default and this would
1518	 * throw us into a horrible recursive echo-echo-echo loop.
1519	 */
1520	hvcs_tty_driver->init_termios = hvcs_tty_termios;
1521	hvcs_tty_driver->flags = TTY_DRIVER_REAL_RAW;
1522
1523	tty_set_operations(hvcs_tty_driver, &hvcs_ops);
1524
1525	/*
1526	 * The following call will result in sysfs entries that denote the
1527	 * dynamically assigned major and minor numbers for our devices.
1528	 */
1529	if (tty_register_driver(hvcs_tty_driver)) {
1530		printk(KERN_ERR "HVCS: registration as a tty driver failed.\n");
1531		rc = -EIO;
1532		goto register_fail;
1533	}
1534
1535	hvcs_pi_buff = kmalloc(PAGE_SIZE, GFP_KERNEL);
1536	if (!hvcs_pi_buff) {
1537		rc = -ENOMEM;
1538		goto buff_alloc_fail;
1539	}
1540
1541	hvcs_task = kthread_run(khvcsd, NULL, "khvcsd");
1542	if (IS_ERR(hvcs_task)) {
1543		printk(KERN_ERR "HVCS: khvcsd creation failed.\n");
1544		rc = -EIO;
1545		goto kthread_fail;
1546	}
1547	mutex_unlock(&hvcs_init_mutex);
1548	return 0;
1549
1550kthread_fail:
1551	kfree(hvcs_pi_buff);
1552buff_alloc_fail:
1553	tty_unregister_driver(hvcs_tty_driver);
1554register_fail:
1555	hvcs_free_index_list();
1556index_fail:
1557	put_tty_driver(hvcs_tty_driver);
1558	hvcs_tty_driver = NULL;
1559	mutex_unlock(&hvcs_init_mutex);
1560	return rc;
1561}
1562
1563static int __init hvcs_module_init(void)
1564{
1565	int rc = vio_register_driver(&hvcs_vio_driver);
1566	if (rc) {
1567		printk(KERN_ERR "HVCS: can't register vio driver\n");
1568		return rc;
1569	}
1570
1571	pr_info("HVCS: Driver registered.\n");
1572
1573	/* This needs to be done AFTER the vio_register_driver() call or else
1574	 * the kobjects won't be initialized properly.
1575	 */
1576	rc = driver_create_file(&(hvcs_vio_driver.driver), &driver_attr_rescan);
1577	if (rc)
1578		pr_warning(KERN_ERR "HVCS: Failed to create rescan file (err %d)\n", rc);
1579
1580	return 0;
1581}
1582
1583static void __exit hvcs_module_exit(void)
1584{
1585	/*
1586	 * This driver receives hvcs_remove callbacks for each device upon
1587	 * module removal.
1588	 */
1589	vio_unregister_driver(&hvcs_vio_driver);
1590	if (!hvcs_task)
1591		return;
1592
1593	/*
1594	 * This synchronous operation  will wake the khvcsd kthread if it is
1595	 * asleep and will return when khvcsd has terminated.
1596	 */
1597	kthread_stop(hvcs_task);
1598
1599	spin_lock(&hvcs_pi_lock);
1600	kfree(hvcs_pi_buff);
1601	hvcs_pi_buff = NULL;
1602	spin_unlock(&hvcs_pi_lock);
1603
1604	driver_remove_file(&hvcs_vio_driver.driver, &driver_attr_rescan);
1605
1606	tty_unregister_driver(hvcs_tty_driver);
1607
1608	hvcs_free_index_list();
1609
1610	put_tty_driver(hvcs_tty_driver);
1611
1612	printk(KERN_INFO "HVCS: driver module removed.\n");
1613}
1614
1615module_init(hvcs_module_init);
1616module_exit(hvcs_module_exit);