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	struct tty_port port;
 265	spinlock_t lock;
 266
 267	/*
 268	 * This index identifies this hvcs device as the complement to a
 269	 * specific tty index.
 270	 */
 271	unsigned int index;
 272
 273	/*
 274	 * Used to tell the driver kernel_thread what operations need to take
 275	 * place upon this hvcs_struct instance.
 276	 */
 277	int todo_mask;
 278
 279	/*
 280	 * This buffer is required so that when hvcs_write_room() reports that
 281	 * it can send HVCS_BUFF_LEN characters that it will buffer the full
 282	 * HVCS_BUFF_LEN characters if need be.  This is essential for opost
 283	 * writes since they do not do high level buffering and expect to be
 284	 * able to send what the driver commits to sending buffering
 285	 * [e.g. tab to space conversions in n_tty.c opost()].
 286	 */
 287	char buffer[HVCS_BUFF_LEN];
 288	int chars_in_buffer;
 289
 290	/*
 291	 * Any variable below is valid before a tty is connected and
 292	 * stays valid after the tty is disconnected.  These shouldn't be
 293	 * whacked until the kobject refcount reaches zero though some entries
 294	 * may be changed via sysfs initiatives.
 295	 */
 296	int connected; /* is the vty-server currently connected to a vty? */
 297	uint32_t p_unit_address; /* partner unit address */
 298	uint32_t p_partition_ID; /* partner partition ID */
 299	char p_location_code[HVCS_CLC_LENGTH + 1]; /* CLC + Null Term */
 300	struct list_head next; /* list management */
 301	struct vio_dev *vdev;
 302};
 303
 304static LIST_HEAD(hvcs_structs);
 305static DEFINE_SPINLOCK(hvcs_structs_lock);
 306static DEFINE_MUTEX(hvcs_init_mutex);
 307
 308static void hvcs_unthrottle(struct tty_struct *tty);
 309static void hvcs_throttle(struct tty_struct *tty);
 310static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance);
 311
 312static int hvcs_write(struct tty_struct *tty,
 313		const unsigned char *buf, int count);
 314static int hvcs_write_room(struct tty_struct *tty);
 315static int hvcs_chars_in_buffer(struct tty_struct *tty);
 316
 317static int hvcs_has_pi(struct hvcs_struct *hvcsd);
 318static void hvcs_set_pi(struct hvcs_partner_info *pi,
 319		struct hvcs_struct *hvcsd);
 320static int hvcs_get_pi(struct hvcs_struct *hvcsd);
 321static int hvcs_rescan_devices_list(void);
 322
 323static int hvcs_partner_connect(struct hvcs_struct *hvcsd);
 324static void hvcs_partner_free(struct hvcs_struct *hvcsd);
 325
 326static int hvcs_enable_device(struct hvcs_struct *hvcsd,
 327		uint32_t unit_address, unsigned int irq, struct vio_dev *dev);
 328
 329static int hvcs_open(struct tty_struct *tty, struct file *filp);
 330static void hvcs_close(struct tty_struct *tty, struct file *filp);
 331static void hvcs_hangup(struct tty_struct * tty);
 332
 333static int hvcs_probe(struct vio_dev *dev,
 334		const struct vio_device_id *id);
 335static int hvcs_remove(struct vio_dev *dev);
 336static int __init hvcs_module_init(void);
 337static void __exit hvcs_module_exit(void);
 338static int hvcs_initialize(void);
 339
 340#define HVCS_SCHED_READ	0x00000001
 341#define HVCS_QUICK_READ	0x00000002
 342#define HVCS_TRY_WRITE	0x00000004
 343#define HVCS_READ_MASK	(HVCS_SCHED_READ | HVCS_QUICK_READ)
 344
 345static inline struct hvcs_struct *from_vio_dev(struct vio_dev *viod)
 346{
 347	return dev_get_drvdata(&viod->dev);
 348}
 349/* The sysfs interface for the driver and devices */
 350
 351static ssize_t hvcs_partner_vtys_show(struct device *dev, struct device_attribute *attr, char *buf)
 352{
 353	struct vio_dev *viod = to_vio_dev(dev);
 354	struct hvcs_struct *hvcsd = from_vio_dev(viod);
 355	unsigned long flags;
 356	int retval;
 357
 358	spin_lock_irqsave(&hvcsd->lock, flags);
 359	retval = sprintf(buf, "%X\n", hvcsd->p_unit_address);
 360	spin_unlock_irqrestore(&hvcsd->lock, flags);
 361	return retval;
 362}
 363static DEVICE_ATTR(partner_vtys, S_IRUGO, hvcs_partner_vtys_show, NULL);
 364
 365static ssize_t hvcs_partner_clcs_show(struct device *dev, struct device_attribute *attr, char *buf)
 366{
 367	struct vio_dev *viod = to_vio_dev(dev);
 368	struct hvcs_struct *hvcsd = from_vio_dev(viod);
 369	unsigned long flags;
 370	int retval;
 371
 372	spin_lock_irqsave(&hvcsd->lock, flags);
 373	retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
 374	spin_unlock_irqrestore(&hvcsd->lock, flags);
 375	return retval;
 376}
 377static DEVICE_ATTR(partner_clcs, S_IRUGO, hvcs_partner_clcs_show, NULL);
 378
 379static ssize_t hvcs_current_vty_store(struct device *dev, struct device_attribute *attr, const char * buf,
 380		size_t count)
 381{
 382	/*
 383	 * Don't need this feature at the present time because firmware doesn't
 384	 * yet support multiple partners.
 385	 */
 386	printk(KERN_INFO "HVCS: Denied current_vty change: -EPERM.\n");
 387	return -EPERM;
 388}
 389
 390static ssize_t hvcs_current_vty_show(struct device *dev, struct device_attribute *attr, char *buf)
 391{
 392	struct vio_dev *viod = to_vio_dev(dev);
 393	struct hvcs_struct *hvcsd = from_vio_dev(viod);
 394	unsigned long flags;
 395	int retval;
 396
 397	spin_lock_irqsave(&hvcsd->lock, flags);
 398	retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
 399	spin_unlock_irqrestore(&hvcsd->lock, flags);
 400	return retval;
 401}
 402
 403static DEVICE_ATTR(current_vty,
 404	S_IRUGO | S_IWUSR, hvcs_current_vty_show, hvcs_current_vty_store);
 405
 406static ssize_t hvcs_vterm_state_store(struct device *dev, struct device_attribute *attr, const char *buf,
 407		size_t count)
 408{
 409	struct vio_dev *viod = to_vio_dev(dev);
 410	struct hvcs_struct *hvcsd = from_vio_dev(viod);
 411	unsigned long flags;
 412
 413	/* writing a '0' to this sysfs entry will result in the disconnect. */
 414	if (simple_strtol(buf, NULL, 0) != 0)
 415		return -EINVAL;
 416
 417	spin_lock_irqsave(&hvcsd->lock, flags);
 418
 419	if (hvcsd->port.count > 0) {
 420		spin_unlock_irqrestore(&hvcsd->lock, flags);
 421		printk(KERN_INFO "HVCS: vterm state unchanged.  "
 422				"The hvcs device node is still in use.\n");
 423		return -EPERM;
 424	}
 425
 426	if (hvcsd->connected == 0) {
 427		spin_unlock_irqrestore(&hvcsd->lock, flags);
 428		printk(KERN_INFO "HVCS: vterm state unchanged. The"
 429				" vty-server is not connected to a vty.\n");
 430		return -EPERM;
 431	}
 432
 433	hvcs_partner_free(hvcsd);
 434	printk(KERN_INFO "HVCS: Closed vty-server@%X and"
 435			" partner vty@%X:%d connection.\n",
 436			hvcsd->vdev->unit_address,
 437			hvcsd->p_unit_address,
 438			(uint32_t)hvcsd->p_partition_ID);
 439
 440	spin_unlock_irqrestore(&hvcsd->lock, flags);
 441	return count;
 442}
 443
 444static ssize_t hvcs_vterm_state_show(struct device *dev, struct device_attribute *attr, char *buf)
 445{
 446	struct vio_dev *viod = to_vio_dev(dev);
 447	struct hvcs_struct *hvcsd = from_vio_dev(viod);
 448	unsigned long flags;
 449	int retval;
 450
 451	spin_lock_irqsave(&hvcsd->lock, flags);
 452	retval = sprintf(buf, "%d\n", hvcsd->connected);
 453	spin_unlock_irqrestore(&hvcsd->lock, flags);
 454	return retval;
 455}
 456static DEVICE_ATTR(vterm_state, S_IRUGO | S_IWUSR,
 457		hvcs_vterm_state_show, hvcs_vterm_state_store);
 458
 459static ssize_t hvcs_index_show(struct device *dev, struct device_attribute *attr, char *buf)
 460{
 461	struct vio_dev *viod = to_vio_dev(dev);
 462	struct hvcs_struct *hvcsd = from_vio_dev(viod);
 463	unsigned long flags;
 464	int retval;
 465
 466	spin_lock_irqsave(&hvcsd->lock, flags);
 467	retval = sprintf(buf, "%d\n", hvcsd->index);
 468	spin_unlock_irqrestore(&hvcsd->lock, flags);
 469	return retval;
 470}
 471
 472static DEVICE_ATTR(index, S_IRUGO, hvcs_index_show, NULL);
 473
 474static struct attribute *hvcs_attrs[] = {
 475	&dev_attr_partner_vtys.attr,
 476	&dev_attr_partner_clcs.attr,
 477	&dev_attr_current_vty.attr,
 478	&dev_attr_vterm_state.attr,
 479	&dev_attr_index.attr,
 480	NULL,
 481};
 482
 483static struct attribute_group hvcs_attr_group = {
 484	.attrs = hvcs_attrs,
 485};
 486
 487static ssize_t hvcs_rescan_show(struct device_driver *ddp, char *buf)
 488{
 489	/* A 1 means it is updating, a 0 means it is done updating */
 490	return snprintf(buf, PAGE_SIZE, "%d\n", hvcs_rescan_status);
 491}
 492
 493static ssize_t hvcs_rescan_store(struct device_driver *ddp, const char * buf,
 494		size_t count)
 495{
 496	if ((simple_strtol(buf, NULL, 0) != 1)
 497		&& (hvcs_rescan_status != 0))
 498		return -EINVAL;
 499
 500	hvcs_rescan_status = 1;
 501	printk(KERN_INFO "HVCS: rescanning partner info for all"
 502		" vty-servers.\n");
 503	hvcs_rescan_devices_list();
 504	hvcs_rescan_status = 0;
 505	return count;
 506}
 507
 508static DRIVER_ATTR(rescan,
 509	S_IRUGO | S_IWUSR, hvcs_rescan_show, hvcs_rescan_store);
 510
 511static void hvcs_kick(void)
 512{
 513	hvcs_kicked = 1;
 514	wmb();
 515	wake_up_process(hvcs_task);
 516}
 517
 518static void hvcs_unthrottle(struct tty_struct *tty)
 519{
 520	struct hvcs_struct *hvcsd = tty->driver_data;
 521	unsigned long flags;
 522
 523	spin_lock_irqsave(&hvcsd->lock, flags);
 524	hvcsd->todo_mask |= HVCS_SCHED_READ;
 525	spin_unlock_irqrestore(&hvcsd->lock, flags);
 526	hvcs_kick();
 527}
 528
 529static void hvcs_throttle(struct tty_struct *tty)
 530{
 531	struct hvcs_struct *hvcsd = tty->driver_data;
 532	unsigned long flags;
 533
 534	spin_lock_irqsave(&hvcsd->lock, flags);
 535	vio_disable_interrupts(hvcsd->vdev);
 536	spin_unlock_irqrestore(&hvcsd->lock, flags);
 537}
 538
 539/*
 540 * If the device is being removed we don't have to worry about this interrupt
 541 * handler taking any further interrupts because they are disabled which means
 542 * the hvcs_struct will always be valid in this handler.
 543 */
 544static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance)
 545{
 546	struct hvcs_struct *hvcsd = dev_instance;
 547
 548	spin_lock(&hvcsd->lock);
 549	vio_disable_interrupts(hvcsd->vdev);
 550	hvcsd->todo_mask |= HVCS_SCHED_READ;
 551	spin_unlock(&hvcsd->lock);
 552	hvcs_kick();
 553
 554	return IRQ_HANDLED;
 555}
 556
 557/* This function must be called with the hvcsd->lock held */
 558static void hvcs_try_write(struct hvcs_struct *hvcsd)
 559{
 560	uint32_t unit_address = hvcsd->vdev->unit_address;
 561	struct tty_struct *tty = hvcsd->port.tty;
 562	int sent;
 563
 564	if (hvcsd->todo_mask & HVCS_TRY_WRITE) {
 565		/* won't send partial writes */
 566		sent = hvc_put_chars(unit_address,
 567				&hvcsd->buffer[0],
 568				hvcsd->chars_in_buffer );
 569		if (sent > 0) {
 570			hvcsd->chars_in_buffer = 0;
 571			/* wmb(); */
 572			hvcsd->todo_mask &= ~(HVCS_TRY_WRITE);
 573			/* wmb(); */
 574
 575			/*
 576			 * We are still obligated to deliver the data to the
 577			 * hypervisor even if the tty has been closed because
 578			 * we committed to delivering it.  But don't try to wake
 579			 * a non-existent tty.
 580			 */
 581			if (tty) {
 582				tty_wakeup(tty);
 583			}
 584		}
 585	}
 586}
 587
 588static int hvcs_io(struct hvcs_struct *hvcsd)
 589{
 590	uint32_t unit_address;
 591	struct tty_struct *tty;
 592	char buf[HVCS_BUFF_LEN] __ALIGNED__;
 593	unsigned long flags;
 594	int got = 0;
 595
 596	spin_lock_irqsave(&hvcsd->lock, flags);
 597
 598	unit_address = hvcsd->vdev->unit_address;
 599	tty = hvcsd->port.tty;
 600
 601	hvcs_try_write(hvcsd);
 602
 603	if (!tty || test_bit(TTY_THROTTLED, &tty->flags)) {
 604		hvcsd->todo_mask &= ~(HVCS_READ_MASK);
 605		goto bail;
 606	} else if (!(hvcsd->todo_mask & (HVCS_READ_MASK)))
 607		goto bail;
 608
 609	/* remove the read masks */
 610	hvcsd->todo_mask &= ~(HVCS_READ_MASK);
 611
 612	if (tty_buffer_request_room(&hvcsd->port, HVCS_BUFF_LEN) >= HVCS_BUFF_LEN) {
 613		got = hvc_get_chars(unit_address,
 614				&buf[0],
 615				HVCS_BUFF_LEN);
 616		tty_insert_flip_string(&hvcsd->port, buf, got);
 617	}
 618
 619	/* Give the TTY time to process the data we just sent. */
 620	if (got)
 621		hvcsd->todo_mask |= HVCS_QUICK_READ;
 622
 623	spin_unlock_irqrestore(&hvcsd->lock, flags);
 624	/* This is synch because tty->low_latency == 1 */
 625	if(got)
 626		tty_flip_buffer_push(&hvcsd->port);
 627
 628	if (!got) {
 629		/* Do this _after_ the flip_buffer_push */
 630		spin_lock_irqsave(&hvcsd->lock, flags);
 631		vio_enable_interrupts(hvcsd->vdev);
 632		spin_unlock_irqrestore(&hvcsd->lock, flags);
 633	}
 634
 635	return hvcsd->todo_mask;
 636
 637 bail:
 638	spin_unlock_irqrestore(&hvcsd->lock, flags);
 639	return hvcsd->todo_mask;
 640}
 641
 642static int khvcsd(void *unused)
 643{
 644	struct hvcs_struct *hvcsd;
 645	int hvcs_todo_mask;
 646
 647	__set_current_state(TASK_RUNNING);
 648
 649	do {
 650		hvcs_todo_mask = 0;
 651		hvcs_kicked = 0;
 652		wmb();
 653
 654		spin_lock(&hvcs_structs_lock);
 655		list_for_each_entry(hvcsd, &hvcs_structs, next) {
 656			hvcs_todo_mask |= hvcs_io(hvcsd);
 657		}
 658		spin_unlock(&hvcs_structs_lock);
 659
 660		/*
 661		 * If any of the hvcs adapters want to try a write or quick read
 662		 * don't schedule(), yield a smidgen then execute the hvcs_io
 663		 * thread again for those that want the write.
 664		 */
 665		 if (hvcs_todo_mask & (HVCS_TRY_WRITE | HVCS_QUICK_READ)) {
 666			yield();
 667			continue;
 668		}
 669
 670		set_current_state(TASK_INTERRUPTIBLE);
 671		if (!hvcs_kicked)
 672			schedule();
 673		__set_current_state(TASK_RUNNING);
 674	} while (!kthread_should_stop());
 675
 676	return 0;
 677}
 678
 679static struct vio_device_id hvcs_driver_table[] = {
 680	{"serial-server", "hvterm2"},
 681	{ "", "" }
 682};
 683MODULE_DEVICE_TABLE(vio, hvcs_driver_table);
 684
 685static void hvcs_return_index(int index)
 686{
 687	/* Paranoia check */
 688	if (!hvcs_index_list)
 689		return;
 690	if (index < 0 || index >= hvcs_index_count)
 691		return;
 692	if (hvcs_index_list[index] == -1)
 693		return;
 694	else
 695		hvcs_index_list[index] = -1;
 696}
 697
 698static void hvcs_destruct_port(struct tty_port *p)
 699{
 700	struct hvcs_struct *hvcsd = container_of(p, struct hvcs_struct, port);
 701	struct vio_dev *vdev;
 702	unsigned long flags;
 703
 704	spin_lock(&hvcs_structs_lock);
 705	spin_lock_irqsave(&hvcsd->lock, flags);
 706
 707	/* the list_del poisons the pointers */
 708	list_del(&(hvcsd->next));
 709
 710	if (hvcsd->connected == 1) {
 711		hvcs_partner_free(hvcsd);
 712		printk(KERN_INFO "HVCS: Closed vty-server@%X and"
 713				" partner vty@%X:%d connection.\n",
 714				hvcsd->vdev->unit_address,
 715				hvcsd->p_unit_address,
 716				(uint32_t)hvcsd->p_partition_ID);
 717	}
 718	printk(KERN_INFO "HVCS: Destroyed hvcs_struct for vty-server@%X.\n",
 719			hvcsd->vdev->unit_address);
 720
 721	vdev = hvcsd->vdev;
 722	hvcsd->vdev = NULL;
 723
 724	hvcsd->p_unit_address = 0;
 725	hvcsd->p_partition_ID = 0;
 726	hvcs_return_index(hvcsd->index);
 727	memset(&hvcsd->p_location_code[0], 0x00, HVCS_CLC_LENGTH + 1);
 728
 729	spin_unlock_irqrestore(&hvcsd->lock, flags);
 730	spin_unlock(&hvcs_structs_lock);
 731
 732	sysfs_remove_group(&vdev->dev.kobj, &hvcs_attr_group);
 733
 734	kfree(hvcsd);
 735}
 736
 737static const struct tty_port_operations hvcs_port_ops = {
 738	.destruct = hvcs_destruct_port,
 739};
 740
 741static int hvcs_get_index(void)
 742{
 743	int i;
 744	/* Paranoia check */
 745	if (!hvcs_index_list) {
 746		printk(KERN_ERR "HVCS: hvcs_index_list NOT valid!.\n");
 747		return -EFAULT;
 748	}
 749	/* Find the numerically lowest first free index. */
 750	for(i = 0; i < hvcs_index_count; i++) {
 751		if (hvcs_index_list[i] == -1) {
 752			hvcs_index_list[i] = 0;
 753			return i;
 754		}
 755	}
 756	return -1;
 757}
 758
 759static int hvcs_probe(
 760	struct vio_dev *dev,
 761	const struct vio_device_id *id)
 762{
 763	struct hvcs_struct *hvcsd;
 764	int index, rc;
 765	int retval;
 766
 767	if (!dev || !id) {
 768		printk(KERN_ERR "HVCS: probed with invalid parameter.\n");
 769		return -EPERM;
 770	}
 771
 772	/* Make sure we are properly initialized */
 773	rc = hvcs_initialize();
 774	if (rc) {
 775		pr_err("HVCS: Failed to initialize core driver.\n");
 776		return rc;
 777	}
 778
 779	/* early to avoid cleanup on failure */
 780	index = hvcs_get_index();
 781	if (index < 0) {
 782		return -EFAULT;
 783	}
 784
 785	hvcsd = kzalloc(sizeof(*hvcsd), GFP_KERNEL);
 786	if (!hvcsd)
 787		return -ENODEV;
 788
 789	tty_port_init(&hvcsd->port);
 790	hvcsd->port.ops = &hvcs_port_ops;
 791	spin_lock_init(&hvcsd->lock);
 792
 793	hvcsd->vdev = dev;
 794	dev_set_drvdata(&dev->dev, hvcsd);
 795
 796	hvcsd->index = index;
 797
 798	/* hvcsd->index = ++hvcs_struct_count; */
 799	hvcsd->chars_in_buffer = 0;
 800	hvcsd->todo_mask = 0;
 801	hvcsd->connected = 0;
 802
 803	/*
 804	 * This will populate the hvcs_struct's partner info fields for the
 805	 * first time.
 806	 */
 807	if (hvcs_get_pi(hvcsd)) {
 808		printk(KERN_ERR "HVCS: Failed to fetch partner"
 809			" info for vty-server@%X on device probe.\n",
 810			hvcsd->vdev->unit_address);
 811	}
 812
 813	/*
 814	 * If a user app opens a tty that corresponds to this vty-server before
 815	 * the hvcs_struct has been added to the devices list then the user app
 816	 * will get -ENODEV.
 817	 */
 818	spin_lock(&hvcs_structs_lock);
 819	list_add_tail(&(hvcsd->next), &hvcs_structs);
 820	spin_unlock(&hvcs_structs_lock);
 821
 822	retval = sysfs_create_group(&dev->dev.kobj, &hvcs_attr_group);
 823	if (retval) {
 824		printk(KERN_ERR "HVCS: Can't create sysfs attrs for vty-server@%X\n",
 825		       hvcsd->vdev->unit_address);
 826		return retval;
 827	}
 828
 829	printk(KERN_INFO "HVCS: vty-server@%X added to the vio bus.\n", dev->unit_address);
 830
 831	/*
 832	 * DON'T enable interrupts here because there is no user to receive the
 833	 * data.
 834	 */
 835	return 0;
 836}
 837
 838static int hvcs_remove(struct vio_dev *dev)
 839{
 840	struct hvcs_struct *hvcsd = dev_get_drvdata(&dev->dev);
 841	unsigned long flags;
 842	struct tty_struct *tty;
 843
 844	if (!hvcsd)
 845		return -ENODEV;
 846
 847	/* By this time the vty-server won't be getting any more interrupts */
 848
 849	spin_lock_irqsave(&hvcsd->lock, flags);
 850
 851	tty = hvcsd->port.tty;
 852
 853	spin_unlock_irqrestore(&hvcsd->lock, flags);
 854
 855	/*
 856	 * Let the last holder of this object cause it to be removed, which
 857	 * would probably be tty_hangup below.
 858	 */
 859	tty_port_put(&hvcsd->port);
 860
 861	/*
 862	 * The hangup is a scheduled function which will auto chain call
 863	 * hvcs_hangup.  The tty should always be valid at this time unless a
 864	 * simultaneous tty close already cleaned up the hvcs_struct.
 865	 */
 866	if (tty)
 867		tty_hangup(tty);
 868
 869	printk(KERN_INFO "HVCS: vty-server@%X removed from the"
 870			" vio bus.\n", dev->unit_address);
 871	return 0;
 872};
 873
 874static struct vio_driver hvcs_vio_driver = {
 875	.id_table	= hvcs_driver_table,
 876	.probe		= hvcs_probe,
 877	.remove		= hvcs_remove,
 878	.name		= hvcs_driver_name,
 879};
 880
 881/* Only called from hvcs_get_pi please */
 882static void hvcs_set_pi(struct hvcs_partner_info *pi, struct hvcs_struct *hvcsd)
 883{
 884	hvcsd->p_unit_address = pi->unit_address;
 885	hvcsd->p_partition_ID  = pi->partition_ID;
 886
 887	/* copy the null-term char too */
 888	strlcpy(&hvcsd->p_location_code[0],
 889			&pi->location_code[0], sizeof(hvcsd->p_location_code));
 890}
 891
 892/*
 893 * Traverse the list and add the partner info that is found to the hvcs_struct
 894 * struct entry. NOTE: At this time I know that partner info will return a
 895 * single entry but in the future there may be multiple partner info entries per
 896 * vty-server and you'll want to zero out that list and reset it.  If for some
 897 * reason you have an old version of this driver but there IS more than one
 898 * partner info then hvcsd->p_* will hold the last partner info data from the
 899 * firmware query.  A good way to update this code would be to replace the three
 900 * partner info fields in hvcs_struct with a list of hvcs_partner_info
 901 * instances.
 902 *
 903 * This function must be called with the hvcsd->lock held.
 904 */
 905static int hvcs_get_pi(struct hvcs_struct *hvcsd)
 906{
 907	struct hvcs_partner_info *pi;
 908	uint32_t unit_address = hvcsd->vdev->unit_address;
 909	struct list_head head;
 910	int retval;
 911
 912	spin_lock(&hvcs_pi_lock);
 913	if (!hvcs_pi_buff) {
 914		spin_unlock(&hvcs_pi_lock);
 915		return -EFAULT;
 916	}
 917	retval = hvcs_get_partner_info(unit_address, &head, hvcs_pi_buff);
 918	spin_unlock(&hvcs_pi_lock);
 919	if (retval) {
 920		printk(KERN_ERR "HVCS: Failed to fetch partner"
 921			" info for vty-server@%x.\n", unit_address);
 922		return retval;
 923	}
 924
 925	/* nixes the values if the partner vty went away */
 926	hvcsd->p_unit_address = 0;
 927	hvcsd->p_partition_ID = 0;
 928
 929	list_for_each_entry(pi, &head, node)
 930		hvcs_set_pi(pi, hvcsd);
 931
 932	hvcs_free_partner_info(&head);
 933	return 0;
 934}
 935
 936/*
 937 * This function is executed by the driver "rescan" sysfs entry.  It shouldn't
 938 * be executed elsewhere, in order to prevent deadlock issues.
 939 */
 940static int hvcs_rescan_devices_list(void)
 941{
 942	struct hvcs_struct *hvcsd;
 943	unsigned long flags;
 944
 945	spin_lock(&hvcs_structs_lock);
 946
 947	list_for_each_entry(hvcsd, &hvcs_structs, next) {
 948		spin_lock_irqsave(&hvcsd->lock, flags);
 949		hvcs_get_pi(hvcsd);
 950		spin_unlock_irqrestore(&hvcsd->lock, flags);
 951	}
 952
 953	spin_unlock(&hvcs_structs_lock);
 954
 955	return 0;
 956}
 957
 958/*
 959 * Farm this off into its own function because it could be more complex once
 960 * multiple partners support is added. This function should be called with
 961 * the hvcsd->lock held.
 962 */
 963static int hvcs_has_pi(struct hvcs_struct *hvcsd)
 964{
 965	if ((!hvcsd->p_unit_address) || (!hvcsd->p_partition_ID))
 966		return 0;
 967	return 1;
 968}
 969
 970/*
 971 * NOTE: It is possible that the super admin removed a partner vty and then
 972 * added a different vty as the new partner.
 973 *
 974 * This function must be called with the hvcsd->lock held.
 975 */
 976static int hvcs_partner_connect(struct hvcs_struct *hvcsd)
 977{
 978	int retval;
 979	unsigned int unit_address = hvcsd->vdev->unit_address;
 980
 981	/*
 982	 * If there wasn't any pi when the device was added it doesn't meant
 983	 * there isn't any now.  This driver isn't notified when a new partner
 984	 * vty is added to a vty-server so we discover changes on our own.
 985	 * Please see comments in hvcs_register_connection() for justification
 986	 * of this bizarre code.
 987	 */
 988	retval = hvcs_register_connection(unit_address,
 989			hvcsd->p_partition_ID,
 990			hvcsd->p_unit_address);
 991	if (!retval) {
 992		hvcsd->connected = 1;
 993		return 0;
 994	} else if (retval != -EINVAL)
 995		return retval;
 996
 997	/*
 998	 * As per the spec re-get the pi and try again if -EINVAL after the
 999	 * first connection attempt.
1000	 */
1001	if (hvcs_get_pi(hvcsd))
1002		return -ENOMEM;
1003
1004	if (!hvcs_has_pi(hvcsd))
1005		return -ENODEV;
1006
1007	retval = hvcs_register_connection(unit_address,
1008			hvcsd->p_partition_ID,
1009			hvcsd->p_unit_address);
1010	if (retval != -EINVAL) {
1011		hvcsd->connected = 1;
1012		return retval;
1013	}
1014
1015	/*
1016	 * EBUSY is the most likely scenario though the vty could have been
1017	 * removed or there really could be an hcall error due to the parameter
1018	 * data but thanks to ambiguous firmware return codes we can't really
1019	 * tell.
1020	 */
1021	printk(KERN_INFO "HVCS: vty-server or partner"
1022			" vty is busy.  Try again later.\n");
1023	return -EBUSY;
1024}
1025
1026/* This function must be called with the hvcsd->lock held */
1027static void hvcs_partner_free(struct hvcs_struct *hvcsd)
1028{
1029	int retval;
1030	do {
1031		retval = hvcs_free_connection(hvcsd->vdev->unit_address);
1032	} while (retval == -EBUSY);
1033	hvcsd->connected = 0;
1034}
1035
1036/* This helper function must be called WITHOUT the hvcsd->lock held */
1037static int hvcs_enable_device(struct hvcs_struct *hvcsd, uint32_t unit_address,
1038		unsigned int irq, struct vio_dev *vdev)
1039{
1040	unsigned long flags;
1041	int rc;
1042
1043	/*
1044	 * It is possible that the vty-server was removed between the time that
1045	 * the conn was registered and now.
1046	 */
1047	rc = request_irq(irq, &hvcs_handle_interrupt, 0, "ibmhvcs", hvcsd);
1048	if (!rc) {
1049		/*
1050		 * It is possible the vty-server was removed after the irq was
1051		 * requested but before we have time to enable interrupts.
1052		 */
1053		if (vio_enable_interrupts(vdev) == H_SUCCESS)
1054			return 0;
1055		else {
1056			printk(KERN_ERR "HVCS: int enable failed for"
1057					" vty-server@%X.\n", unit_address);
1058			free_irq(irq, hvcsd);
1059		}
1060	} else
1061		printk(KERN_ERR "HVCS: irq req failed for"
1062				" vty-server@%X.\n", unit_address);
1063
1064	spin_lock_irqsave(&hvcsd->lock, flags);
1065	hvcs_partner_free(hvcsd);
1066	spin_unlock_irqrestore(&hvcsd->lock, flags);
1067
1068	return rc;
1069
1070}
1071
1072/*
1073 * This always increments the kref ref count if the call is successful.
1074 * Please remember to dec when you are done with the instance.
1075 *
1076 * NOTICE: Do NOT hold either the hvcs_struct.lock or hvcs_structs_lock when
1077 * calling this function or you will get deadlock.
1078 */
1079static struct hvcs_struct *hvcs_get_by_index(int index)
1080{
1081	struct hvcs_struct *hvcsd;
1082	unsigned long flags;
1083
1084	spin_lock(&hvcs_structs_lock);
1085	list_for_each_entry(hvcsd, &hvcs_structs, next) {
1086		spin_lock_irqsave(&hvcsd->lock, flags);
1087		if (hvcsd->index == index) {
1088			tty_port_get(&hvcsd->port);
1089			spin_unlock_irqrestore(&hvcsd->lock, flags);
1090			spin_unlock(&hvcs_structs_lock);
1091			return hvcsd;
1092		}
1093		spin_unlock_irqrestore(&hvcsd->lock, flags);
1094	}
1095	spin_unlock(&hvcs_structs_lock);
1096
1097	return NULL;
1098}
1099
1100static int hvcs_install(struct tty_driver *driver, struct tty_struct *tty)
1101{
1102	struct hvcs_struct *hvcsd;
1103	struct vio_dev *vdev;
1104	unsigned long unit_address, flags;
1105	unsigned int irq;
1106	int retval;
1107
1108	/*
1109	 * Is there a vty-server that shares the same index?
1110	 * This function increments the kref index.
1111	 */
1112	hvcsd = hvcs_get_by_index(tty->index);
1113	if (!hvcsd) {
1114		printk(KERN_WARNING "HVCS: open failed, no device associated"
1115				" with tty->index %d.\n", tty->index);
1116		return -ENODEV;
1117	}
1118
1119	spin_lock_irqsave(&hvcsd->lock, flags);
1120
1121	if (hvcsd->connected == 0) {
1122		retval = hvcs_partner_connect(hvcsd);
1123		if (retval) {
1124			spin_unlock_irqrestore(&hvcsd->lock, flags);
1125			printk(KERN_WARNING "HVCS: partner connect failed.\n");
1126			goto err_put;
1127		}
1128	}
1129
1130	hvcsd->port.count = 0;
1131	hvcsd->port.tty = tty;
1132	tty->driver_data = hvcsd;
1133
1134	memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1135
1136	/*
1137	 * Save these in the spinlock for the enable operations that need them
1138	 * outside of the spinlock.
1139	 */
1140	irq = hvcsd->vdev->irq;
1141	vdev = hvcsd->vdev;
1142	unit_address = hvcsd->vdev->unit_address;
1143
1144	hvcsd->todo_mask |= HVCS_SCHED_READ;
1145	spin_unlock_irqrestore(&hvcsd->lock, flags);
1146
1147	/*
1148	 * This must be done outside of the spinlock because it requests irqs
1149	 * and will grab the spinlock and free the connection if it fails.
1150	 */
1151	retval = hvcs_enable_device(hvcsd, unit_address, irq, vdev);
1152	if (retval) {
1153		printk(KERN_WARNING "HVCS: enable device failed.\n");
1154		goto err_put;
1155	}
1156
1157	retval = tty_port_install(&hvcsd->port, driver, tty);
1158	if (retval)
1159		goto err_irq;
1160
1161	return 0;
1162err_irq:
1163	spin_lock_irqsave(&hvcsd->lock, flags);
1164	vio_disable_interrupts(hvcsd->vdev);
1165	spin_unlock_irqrestore(&hvcsd->lock, flags);
1166	free_irq(irq, hvcsd);
1167err_put:
1168	tty_port_put(&hvcsd->port);
1169
1170	return retval;
1171}
1172
1173/*
1174 * This is invoked via the tty_open interface when a user app connects to the
1175 * /dev node.
1176 */
1177static int hvcs_open(struct tty_struct *tty, struct file *filp)
1178{
1179	struct hvcs_struct *hvcsd = tty->driver_data;
1180	unsigned long flags;
1181
1182	spin_lock_irqsave(&hvcsd->lock, flags);
1183	hvcsd->port.count++;
1184	hvcsd->todo_mask |= HVCS_SCHED_READ;
1185	spin_unlock_irqrestore(&hvcsd->lock, flags);
1186
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}
1194
1195static void hvcs_close(struct tty_struct *tty, struct file *filp)
1196{
1197	struct hvcs_struct *hvcsd;
1198	unsigned long flags;
1199	int irq;
1200
1201	/*
1202	 * Is someone trying to close the file associated with this device after
1203	 * we have hung up?  If so tty->driver_data wouldn't be valid.
1204	 */
1205	if (tty_hung_up_p(filp))
1206		return;
1207
1208	/*
1209	 * No driver_data means that this close was probably issued after a
1210	 * failed hvcs_open by the tty layer's release_dev() api and we can just
1211	 * exit cleanly.
1212	 */
1213	if (!tty->driver_data)
1214		return;
1215
1216	hvcsd = tty->driver_data;
1217
1218	spin_lock_irqsave(&hvcsd->lock, flags);
1219	if (--hvcsd->port.count == 0) {
1220
1221		vio_disable_interrupts(hvcsd->vdev);
1222
1223		/*
1224		 * NULL this early so that the kernel_thread doesn't try to
1225		 * execute any operations on the TTY even though it is obligated
1226		 * to deliver any pending I/O to the hypervisor.
1227		 */
1228		hvcsd->port.tty = NULL;
1229
1230		irq = hvcsd->vdev->irq;
1231		spin_unlock_irqrestore(&hvcsd->lock, flags);
1232
1233		tty_wait_until_sent(tty, HVCS_CLOSE_WAIT);
1234
1235		/*
1236		 * This line is important because it tells hvcs_open that this
1237		 * device needs to be re-configured the next time hvcs_open is
1238		 * called.
1239		 */
1240		tty->driver_data = NULL;
1241
1242		free_irq(irq, hvcsd);
1243		return;
1244	} else if (hvcsd->port.count < 0) {
1245		printk(KERN_ERR "HVCS: vty-server@%X open_count: %d"
1246				" is missmanaged.\n",
1247		hvcsd->vdev->unit_address, hvcsd->port.count);
1248	}
1249
1250	spin_unlock_irqrestore(&hvcsd->lock, flags);
1251}
1252
1253static void hvcs_cleanup(struct tty_struct * tty)
1254{
1255	struct hvcs_struct *hvcsd = tty->driver_data;
1256
1257	tty_port_put(&hvcsd->port);
1258}
1259
1260static void hvcs_hangup(struct tty_struct * tty)
1261{
1262	struct hvcs_struct *hvcsd = tty->driver_data;
1263	unsigned long flags;
1264	int temp_open_count;
1265	int irq;
1266
1267	spin_lock_irqsave(&hvcsd->lock, flags);
1268	/* Preserve this so that we know how many kref refs to put */
1269	temp_open_count = hvcsd->port.count;
1270
1271	/*
1272	 * Don't kref put inside the spinlock because the destruction
1273	 * callback may use the spinlock and it may get called before the
1274	 * spinlock has been released.
1275	 */
1276	vio_disable_interrupts(hvcsd->vdev);
1277
1278	hvcsd->todo_mask = 0;
1279
1280	/* I don't think the tty needs the hvcs_struct pointer after a hangup */
1281	tty->driver_data = NULL;
1282	hvcsd->port.tty = NULL;
1283
1284	hvcsd->port.count = 0;
1285
1286	/* This will drop any buffered data on the floor which is OK in a hangup
1287	 * scenario. */
1288	memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1289	hvcsd->chars_in_buffer = 0;
1290
1291	irq = hvcsd->vdev->irq;
1292
1293	spin_unlock_irqrestore(&hvcsd->lock, flags);
1294
1295	free_irq(irq, hvcsd);
1296
1297	/*
1298	 * We need to kref_put() for every open_count we have since the
1299	 * tty_hangup() function doesn't invoke a close per open connection on a
1300	 * non-console device.
1301	 */
1302	while(temp_open_count) {
1303		--temp_open_count;
1304		/*
1305		 * The final put will trigger destruction of the hvcs_struct.
1306		 * NOTE:  If this hangup was signaled from user space then the
1307		 * final put will never happen.
1308		 */
1309		tty_port_put(&hvcsd->port);
1310	}
1311}
1312
1313/*
1314 * NOTE: This is almost always from_user since user level apps interact with the
1315 * /dev nodes. I'm trusting that if hvcs_write gets called and interrupted by
1316 * hvcs_remove (which removes the target device and executes tty_hangup()) that
1317 * tty_hangup will allow hvcs_write time to complete execution before it
1318 * terminates our device.
1319 */
1320static int hvcs_write(struct tty_struct *tty,
1321		const unsigned char *buf, int count)
1322{
1323	struct hvcs_struct *hvcsd = tty->driver_data;
1324	unsigned int unit_address;
1325	const unsigned char *charbuf;
1326	unsigned long flags;
1327	int total_sent = 0;
1328	int tosend = 0;
1329	int result = 0;
1330
1331	/*
1332	 * If they don't check the return code off of their open they may
1333	 * attempt this even if there is no connected device.
1334	 */
1335	if (!hvcsd)
1336		return -ENODEV;
1337
1338	/* Reasonable size to prevent user level flooding */
1339	if (count > HVCS_MAX_FROM_USER) {
1340		printk(KERN_WARNING "HVCS write: count being truncated to"
1341				" HVCS_MAX_FROM_USER.\n");
1342		count = HVCS_MAX_FROM_USER;
1343	}
1344
1345	charbuf = buf;
1346
1347	spin_lock_irqsave(&hvcsd->lock, flags);
1348
1349	/*
1350	 * Somehow an open succeeded but the device was removed or the
1351	 * connection terminated between the vty-server and partner vty during
1352	 * the middle of a write operation?  This is a crummy place to do this
1353	 * but we want to keep it all in the spinlock.
1354	 */
1355	if (hvcsd->port.count <= 0) {
1356		spin_unlock_irqrestore(&hvcsd->lock, flags);
1357		return -ENODEV;
1358	}
1359
1360	unit_address = hvcsd->vdev->unit_address;
1361
1362	while (count > 0) {
1363		tosend = min(count, (HVCS_BUFF_LEN - hvcsd->chars_in_buffer));
1364		/*
1365		 * No more space, this probably means that the last call to
1366		 * hvcs_write() didn't succeed and the buffer was filled up.
1367		 */
1368		if (!tosend)
1369			break;
1370
1371		memcpy(&hvcsd->buffer[hvcsd->chars_in_buffer],
1372				&charbuf[total_sent],
1373				tosend);
1374
1375		hvcsd->chars_in_buffer += tosend;
1376
1377		result = 0;
1378
1379		/*
1380		 * If this is true then we don't want to try writing to the
1381		 * hypervisor because that is the kernel_threads job now.  We'll
1382		 * just add to the buffer.
1383		 */
1384		if (!(hvcsd->todo_mask & HVCS_TRY_WRITE))
1385			/* won't send partial writes */
1386			result = hvc_put_chars(unit_address,
1387					&hvcsd->buffer[0],
1388					hvcsd->chars_in_buffer);
1389
1390		/*
1391		 * Since we know we have enough room in hvcsd->buffer for
1392		 * tosend we record that it was sent regardless of whether the
1393		 * hypervisor actually took it because we have it buffered.
1394		 */
1395		total_sent+=tosend;
1396		count-=tosend;
1397		if (result == 0) {
1398			hvcsd->todo_mask |= HVCS_TRY_WRITE;
1399			hvcs_kick();
1400			break;
1401		}
1402
1403		hvcsd->chars_in_buffer = 0;
1404		/*
1405		 * Test after the chars_in_buffer reset otherwise this could
1406		 * deadlock our writes if hvc_put_chars fails.
1407		 */
1408		if (result < 0)
1409			break;
1410	}
1411
1412	spin_unlock_irqrestore(&hvcsd->lock, flags);
1413
1414	if (result == -1)
1415		return -EIO;
1416	else
1417		return total_sent;
1418}
1419
1420/*
1421 * This is really asking how much can we guarantee that we can send or that we
1422 * absolutely WILL BUFFER if we can't send it.  This driver MUST honor the
1423 * return value, hence the reason for hvcs_struct buffering.
1424 */
1425static int hvcs_write_room(struct tty_struct *tty)
1426{
1427	struct hvcs_struct *hvcsd = tty->driver_data;
1428
1429	if (!hvcsd || hvcsd->port.count <= 0)
1430		return 0;
1431
1432	return HVCS_BUFF_LEN - hvcsd->chars_in_buffer;
1433}
1434
1435static int hvcs_chars_in_buffer(struct tty_struct *tty)
1436{
1437	struct hvcs_struct *hvcsd = tty->driver_data;
1438
1439	return hvcsd->chars_in_buffer;
1440}
1441
1442static const struct tty_operations hvcs_ops = {
1443	.install = hvcs_install,
1444	.open = hvcs_open,
1445	.close = hvcs_close,
1446	.cleanup = hvcs_cleanup,
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 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		mutex_unlock(&hvcs_init_mutex);
1496		return -ENOMEM;
1497	}
1498
1499	if (hvcs_alloc_index_list(num_ttys_to_alloc)) {
1500		rc = -ENOMEM;
1501		goto index_fail;
1502	}
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 = (unsigned long *) __get_free_page(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	free_page((unsigned long)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("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	free_page((unsigned long)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);