linux/drivers/char/hvcs.c
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   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 similarily 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 koject 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);
 312
 313static void hvcs_unthrottle(struct tty_struct *tty);
 314static void hvcs_throttle(struct tty_struct *tty);
 315static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance);
 316
 317static int hvcs_write(struct tty_struct *tty,
 318                const unsigned char *buf, int count);
 319static int hvcs_write_room(struct tty_struct *tty);
 320static int hvcs_chars_in_buffer(struct tty_struct *tty);
 321
 322static int hvcs_has_pi(struct hvcs_struct *hvcsd);
 323static void hvcs_set_pi(struct hvcs_partner_info *pi,
 324                struct hvcs_struct *hvcsd);
 325static int hvcs_get_pi(struct hvcs_struct *hvcsd);
 326static int hvcs_rescan_devices_list(void);
 327
 328static int hvcs_partner_connect(struct hvcs_struct *hvcsd);
 329static void hvcs_partner_free(struct hvcs_struct *hvcsd);
 330
 331static int hvcs_enable_device(struct hvcs_struct *hvcsd,
 332                uint32_t unit_address, unsigned int irq, struct vio_dev *dev);
 333
 334static int hvcs_open(struct tty_struct *tty, struct file *filp);
 335static void hvcs_close(struct tty_struct *tty, struct file *filp);
 336static void hvcs_hangup(struct tty_struct * tty);
 337
 338static int __devinit hvcs_probe(struct vio_dev *dev,
 339                const struct vio_device_id *id);
 340static int __devexit hvcs_remove(struct vio_dev *dev);
 341static int __init hvcs_module_init(void);
 342static void __exit hvcs_module_exit(void);
 343
 344#define HVCS_SCHED_READ 0x00000001
 345#define HVCS_QUICK_READ 0x00000002
 346#define HVCS_TRY_WRITE  0x00000004
 347#define HVCS_READ_MASK  (HVCS_SCHED_READ | HVCS_QUICK_READ)
 348
 349static inline struct hvcs_struct *from_vio_dev(struct vio_dev *viod)
 350{
 351        return dev_get_drvdata(&viod->dev);
 352}
 353/* The sysfs interface for the driver and devices */
 354
 355static ssize_t hvcs_partner_vtys_show(struct device *dev, struct device_attribute *attr, char *buf)
 356{
 357        struct vio_dev *viod = to_vio_dev(dev);
 358        struct hvcs_struct *hvcsd = from_vio_dev(viod);
 359        unsigned long flags;
 360        int retval;
 361
 362        spin_lock_irqsave(&hvcsd->lock, flags);
 363        retval = sprintf(buf, "%X\n", hvcsd->p_unit_address);
 364        spin_unlock_irqrestore(&hvcsd->lock, flags);
 365        return retval;
 366}
 367static DEVICE_ATTR(partner_vtys, S_IRUGO, hvcs_partner_vtys_show, NULL);
 368
 369static ssize_t hvcs_partner_clcs_show(struct device *dev, struct device_attribute *attr, char *buf)
 370{
 371        struct vio_dev *viod = to_vio_dev(dev);
 372        struct hvcs_struct *hvcsd = from_vio_dev(viod);
 373        unsigned long flags;
 374        int retval;
 375
 376        spin_lock_irqsave(&hvcsd->lock, flags);
 377        retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
 378        spin_unlock_irqrestore(&hvcsd->lock, flags);
 379        return retval;
 380}
 381static DEVICE_ATTR(partner_clcs, S_IRUGO, hvcs_partner_clcs_show, NULL);
 382
 383static ssize_t hvcs_current_vty_store(struct device *dev, struct device_attribute *attr, const char * buf,
 384                size_t count)
 385{
 386        /*
 387         * Don't need this feature at the present time because firmware doesn't
 388         * yet support multiple partners.
 389         */
 390        printk(KERN_INFO "HVCS: Denied current_vty change: -EPERM.\n");
 391        return -EPERM;
 392}
 393
 394static ssize_t hvcs_current_vty_show(struct device *dev, struct device_attribute *attr, char *buf)
 395{
 396        struct vio_dev *viod = to_vio_dev(dev);
 397        struct hvcs_struct *hvcsd = from_vio_dev(viod);
 398        unsigned long flags;
 399        int retval;
 400
 401        spin_lock_irqsave(&hvcsd->lock, flags);
 402        retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
 403        spin_unlock_irqrestore(&hvcsd->lock, flags);
 404        return retval;
 405}
 406
 407static DEVICE_ATTR(current_vty,
 408        S_IRUGO | S_IWUSR, hvcs_current_vty_show, hvcs_current_vty_store);
 409
 410static ssize_t hvcs_vterm_state_store(struct device *dev, struct device_attribute *attr, const char *buf,
 411                size_t count)
 412{
 413        struct vio_dev *viod = to_vio_dev(dev);
 414        struct hvcs_struct *hvcsd = from_vio_dev(viod);
 415        unsigned long flags;
 416
 417        /* writing a '0' to this sysfs entry will result in the disconnect. */
 418        if (simple_strtol(buf, NULL, 0) != 0)
 419                return -EINVAL;
 420
 421        spin_lock_irqsave(&hvcsd->lock, flags);
 422
 423        if (hvcsd->open_count > 0) {
 424                spin_unlock_irqrestore(&hvcsd->lock, flags);
 425                printk(KERN_INFO "HVCS: vterm state unchanged.  "
 426                                "The hvcs device node is still in use.\n");
 427                return -EPERM;
 428        }
 429
 430        if (hvcsd->connected == 0) {
 431                spin_unlock_irqrestore(&hvcsd->lock, flags);
 432                printk(KERN_INFO "HVCS: vterm state unchanged. The"
 433                                " vty-server is not connected to a vty.\n");
 434                return -EPERM;
 435        }
 436
 437        hvcs_partner_free(hvcsd);
 438        printk(KERN_INFO "HVCS: Closed vty-server@%X and"
 439                        " partner vty@%X:%d connection.\n",
 440                        hvcsd->vdev->unit_address,
 441                        hvcsd->p_unit_address,
 442                        (uint32_t)hvcsd->p_partition_ID);
 443
 444        spin_unlock_irqrestore(&hvcsd->lock, flags);
 445        return count;
 446}
 447
 448static ssize_t hvcs_vterm_state_show(struct device *dev, struct device_attribute *attr, char *buf)
 449{
 450        struct vio_dev *viod = to_vio_dev(dev);
 451        struct hvcs_struct *hvcsd = from_vio_dev(viod);
 452        unsigned long flags;
 453        int retval;
 454
 455        spin_lock_irqsave(&hvcsd->lock, flags);
 456        retval = sprintf(buf, "%d\n", hvcsd->connected);
 457        spin_unlock_irqrestore(&hvcsd->lock, flags);
 458        return retval;
 459}
 460static DEVICE_ATTR(vterm_state, S_IRUGO | S_IWUSR,
 461                hvcs_vterm_state_show, hvcs_vterm_state_store);
 462
 463static ssize_t hvcs_index_show(struct device *dev, struct device_attribute *attr, char *buf)
 464{
 465        struct vio_dev *viod = to_vio_dev(dev);
 466        struct hvcs_struct *hvcsd = from_vio_dev(viod);
 467        unsigned long flags;
 468        int retval;
 469
 470        spin_lock_irqsave(&hvcsd->lock, flags);
 471        retval = sprintf(buf, "%d\n", hvcsd->index);
 472        spin_unlock_irqrestore(&hvcsd->lock, flags);
 473        return retval;
 474}
 475
 476static DEVICE_ATTR(index, S_IRUGO, hvcs_index_show, NULL);
 477
 478static struct attribute *hvcs_attrs[] = {
 479        &dev_attr_partner_vtys.attr,
 480        &dev_attr_partner_clcs.attr,
 481        &dev_attr_current_vty.attr,
 482        &dev_attr_vterm_state.attr,
 483        &dev_attr_index.attr,
 484        NULL,
 485};
 486
 487static struct attribute_group hvcs_attr_group = {
 488        .attrs = hvcs_attrs,
 489};
 490
 491static ssize_t hvcs_rescan_show(struct device_driver *ddp, char *buf)
 492{
 493        /* A 1 means it is updating, a 0 means it is done updating */
 494        return snprintf(buf, PAGE_SIZE, "%d\n", hvcs_rescan_status);
 495}
 496
 497static ssize_t hvcs_rescan_store(struct device_driver *ddp, const char * buf,
 498                size_t count)
 499{
 500        if ((simple_strtol(buf, NULL, 0) != 1)
 501                && (hvcs_rescan_status != 0))
 502                return -EINVAL;
 503
 504        hvcs_rescan_status = 1;
 505        printk(KERN_INFO "HVCS: rescanning partner info for all"
 506                " vty-servers.\n");
 507        hvcs_rescan_devices_list();
 508        hvcs_rescan_status = 0;
 509        return count;
 510}
 511
 512static DRIVER_ATTR(rescan,
 513        S_IRUGO | S_IWUSR, hvcs_rescan_show, hvcs_rescan_store);
 514
 515static void hvcs_kick(void)
 516{
 517        hvcs_kicked = 1;
 518        wmb();
 519        wake_up_process(hvcs_task);
 520}
 521
 522static void hvcs_unthrottle(struct tty_struct *tty)
 523{
 524        struct hvcs_struct *hvcsd = tty->driver_data;
 525        unsigned long flags;
 526
 527        spin_lock_irqsave(&hvcsd->lock, flags);
 528        hvcsd->todo_mask |= HVCS_SCHED_READ;
 529        spin_unlock_irqrestore(&hvcsd->lock, flags);
 530        hvcs_kick();
 531}
 532
 533static void hvcs_throttle(struct tty_struct *tty)
 534{
 535        struct hvcs_struct *hvcsd = tty->driver_data;
 536        unsigned long flags;
 537
 538        spin_lock_irqsave(&hvcsd->lock, flags);
 539        vio_disable_interrupts(hvcsd->vdev);
 540        spin_unlock_irqrestore(&hvcsd->lock, flags);
 541}
 542
 543/*
 544 * If the device is being removed we don't have to worry about this interrupt
 545 * handler taking any further interrupts because they are disabled which means
 546 * the hvcs_struct will always be valid in this handler.
 547 */
 548static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance)
 549{
 550        struct hvcs_struct *hvcsd = dev_instance;
 551
 552        spin_lock(&hvcsd->lock);
 553        vio_disable_interrupts(hvcsd->vdev);
 554        hvcsd->todo_mask |= HVCS_SCHED_READ;
 555        spin_unlock(&hvcsd->lock);
 556        hvcs_kick();
 557
 558        return IRQ_HANDLED;
 559}
 560
 561/* This function must be called with the hvcsd->lock held */
 562static void hvcs_try_write(struct hvcs_struct *hvcsd)
 563{
 564        uint32_t unit_address = hvcsd->vdev->unit_address;
 565        struct tty_struct *tty = hvcsd->tty;
 566        int sent;
 567
 568        if (hvcsd->todo_mask & HVCS_TRY_WRITE) {
 569                /* won't send partial writes */
 570                sent = hvc_put_chars(unit_address,
 571                                &hvcsd->buffer[0],
 572                                hvcsd->chars_in_buffer );
 573                if (sent > 0) {
 574                        hvcsd->chars_in_buffer = 0;
 575                        /* wmb(); */
 576                        hvcsd->todo_mask &= ~(HVCS_TRY_WRITE);
 577                        /* wmb(); */
 578
 579                        /*
 580                         * We are still obligated to deliver the data to the
 581                         * hypervisor even if the tty has been closed because
 582                         * we commited to delivering it.  But don't try to wake
 583                         * a non-existent tty.
 584                         */
 585                        if (tty) {
 586                                tty_wakeup(tty);
 587                        }
 588                }
 589        }
 590}
 591
 592static int hvcs_io(struct hvcs_struct *hvcsd)
 593{
 594        uint32_t unit_address;
 595        struct tty_struct *tty;
 596        char buf[HVCS_BUFF_LEN] __ALIGNED__;
 597        unsigned long flags;
 598        int got = 0;
 599
 600        spin_lock_irqsave(&hvcsd->lock, flags);
 601
 602        unit_address = hvcsd->vdev->unit_address;
 603        tty = hvcsd->tty;
 604
 605        hvcs_try_write(hvcsd);
 606
 607        if (!tty || test_bit(TTY_THROTTLED, &tty->flags)) {
 608                hvcsd->todo_mask &= ~(HVCS_READ_MASK);
 609                goto bail;
 610        } else if (!(hvcsd->todo_mask & (HVCS_READ_MASK)))
 611                goto bail;
 612
 613        /* remove the read masks */
 614        hvcsd->todo_mask &= ~(HVCS_READ_MASK);
 615
 616        if (tty_buffer_request_room(tty, HVCS_BUFF_LEN) >= HVCS_BUFF_LEN) {
 617                got = hvc_get_chars(unit_address,
 618                                &buf[0],
 619                                HVCS_BUFF_LEN);
 620                tty_insert_flip_string(tty, buf, got);
 621        }
 622
 623        /* Give the TTY time to process the data we just sent. */
 624        if (got)
 625                hvcsd->todo_mask |= HVCS_QUICK_READ;
 626
 627        spin_unlock_irqrestore(&hvcsd->lock, flags);
 628        /* This is synch because tty->low_latency == 1 */
 629        if(got)
 630                tty_flip_buffer_push(tty);
 631
 632        if (!got) {
 633                /* Do this _after_ the flip_buffer_push */
 634                spin_lock_irqsave(&hvcsd->lock, flags);
 635                vio_enable_interrupts(hvcsd->vdev);
 636                spin_unlock_irqrestore(&hvcsd->lock, flags);
 637        }
 638
 639        return hvcsd->todo_mask;
 640
 641 bail:
 642        spin_unlock_irqrestore(&hvcsd->lock, flags);
 643        return hvcsd->todo_mask;
 644}
 645
 646static int khvcsd(void *unused)
 647{
 648        struct hvcs_struct *hvcsd;
 649        int hvcs_todo_mask;
 650
 651        __set_current_state(TASK_RUNNING);
 652
 653        do {
 654                hvcs_todo_mask = 0;
 655                hvcs_kicked = 0;
 656                wmb();
 657
 658                spin_lock(&hvcs_structs_lock);
 659                list_for_each_entry(hvcsd, &hvcs_structs, next) {
 660                        hvcs_todo_mask |= hvcs_io(hvcsd);
 661                }
 662                spin_unlock(&hvcs_structs_lock);
 663
 664                /*
 665                 * If any of the hvcs adapters want to try a write or quick read
 666                 * don't schedule(), yield a smidgen then execute the hvcs_io
 667                 * thread again for those that want the write.
 668                 */
 669                 if (hvcs_todo_mask & (HVCS_TRY_WRITE | HVCS_QUICK_READ)) {
 670                        yield();
 671                        continue;
 672                }
 673
 674                set_current_state(TASK_INTERRUPTIBLE);
 675                if (!hvcs_kicked)
 676                        schedule();
 677                __set_current_state(TASK_RUNNING);
 678        } while (!kthread_should_stop());
 679
 680        return 0;
 681}
 682
 683static struct vio_device_id hvcs_driver_table[] __devinitdata= {
 684        {"serial-server", "hvterm2"},
 685        { "", "" }
 686};
 687MODULE_DEVICE_TABLE(vio, hvcs_driver_table);
 688
 689static void hvcs_return_index(int index)
 690{
 691        /* Paranoia check */
 692        if (!hvcs_index_list)
 693                return;
 694        if (index < 0 || index >= hvcs_index_count)
 695                return;
 696        if (hvcs_index_list[index] == -1)
 697                return;
 698        else
 699                hvcs_index_list[index] = -1;
 700}
 701
 702/* callback when the kref ref count reaches zero */
 703static void destroy_hvcs_struct(struct kref *kref)
 704{
 705        struct hvcs_struct *hvcsd = from_kref(kref);
 706        struct vio_dev *vdev;
 707        unsigned long flags;
 708
 709        spin_lock(&hvcs_structs_lock);
 710        spin_lock_irqsave(&hvcsd->lock, flags);
 711
 712        /* the list_del poisons the pointers */
 713        list_del(&(hvcsd->next));
 714
 715        if (hvcsd->connected == 1) {
 716                hvcs_partner_free(hvcsd);
 717                printk(KERN_INFO "HVCS: Closed vty-server@%X and"
 718                                " partner vty@%X:%d connection.\n",
 719                                hvcsd->vdev->unit_address,
 720                                hvcsd->p_unit_address,
 721                                (uint32_t)hvcsd->p_partition_ID);
 722        }
 723        printk(KERN_INFO "HVCS: Destroyed hvcs_struct for vty-server@%X.\n",
 724                        hvcsd->vdev->unit_address);
 725
 726        vdev = hvcsd->vdev;
 727        hvcsd->vdev = NULL;
 728
 729        hvcsd->p_unit_address = 0;
 730        hvcsd->p_partition_ID = 0;
 731        hvcs_return_index(hvcsd->index);
 732        memset(&hvcsd->p_location_code[0], 0x00, HVCS_CLC_LENGTH + 1);
 733
 734        spin_unlock_irqrestore(&hvcsd->lock, flags);
 735        spin_unlock(&hvcs_structs_lock);
 736
 737        sysfs_remove_group(&vdev->dev.kobj, &hvcs_attr_group);
 738
 739        kfree(hvcsd);
 740}
 741
 742static int hvcs_get_index(void)
 743{
 744        int i;
 745        /* Paranoia check */
 746        if (!hvcs_index_list) {
 747                printk(KERN_ERR "HVCS: hvcs_index_list NOT valid!.\n");
 748                return -EFAULT;
 749        }
 750        /* Find the numerically lowest first free index. */
 751        for(i = 0; i < hvcs_index_count; i++) {
 752                if (hvcs_index_list[i] == -1) {
 753                        hvcs_index_list[i] = 0;
 754                        return i;
 755                }
 756        }
 757        return -1;
 758}
 759
 760static int __devinit hvcs_probe(
 761        struct vio_dev *dev,
 762        const struct vio_device_id *id)
 763{
 764        struct hvcs_struct *hvcsd;
 765        int index;
 766        int retval;
 767
 768        if (!dev || !id) {
 769                printk(KERN_ERR "HVCS: probed with invalid parameter.\n");
 770                return -EPERM;
 771        }
 772
 773        /* early to avoid cleanup on failure */
 774        index = hvcs_get_index();
 775        if (index < 0) {
 776                return -EFAULT;
 777        }
 778
 779        hvcsd = kzalloc(sizeof(*hvcsd), GFP_KERNEL);
 780        if (!hvcsd)
 781                return -ENODEV;
 782
 783
 784        spin_lock_init(&hvcsd->lock);
 785        /* Automatically incs the refcount the first time */
 786        kref_init(&hvcsd->kref);
 787
 788        hvcsd->vdev = dev;
 789        dev_set_drvdata(&dev->dev, hvcsd);
 790
 791        hvcsd->index = index;
 792
 793        /* hvcsd->index = ++hvcs_struct_count; */
 794        hvcsd->chars_in_buffer = 0;
 795        hvcsd->todo_mask = 0;
 796        hvcsd->connected = 0;
 797
 798        /*
 799         * This will populate the hvcs_struct's partner info fields for the
 800         * first time.
 801         */
 802        if (hvcs_get_pi(hvcsd)) {
 803                printk(KERN_ERR "HVCS: Failed to fetch partner"
 804                        " info for vty-server@%X on device probe.\n",
 805                        hvcsd->vdev->unit_address);
 806        }
 807
 808        /*
 809         * If a user app opens a tty that corresponds to this vty-server before
 810         * the hvcs_struct has been added to the devices list then the user app
 811         * will get -ENODEV.
 812         */
 813        spin_lock(&hvcs_structs_lock);
 814        list_add_tail(&(hvcsd->next), &hvcs_structs);
 815        spin_unlock(&hvcs_structs_lock);
 816
 817        retval = sysfs_create_group(&dev->dev.kobj, &hvcs_attr_group);
 818        if (retval) {
 819                printk(KERN_ERR "HVCS: Can't create sysfs attrs for vty-server@%X\n",
 820                       hvcsd->vdev->unit_address);
 821                return retval;
 822        }
 823
 824        printk(KERN_INFO "HVCS: vty-server@%X added to the vio bus.\n", dev->unit_address);
 825
 826        /*
 827         * DON'T enable interrupts here because there is no user to receive the
 828         * data.
 829         */
 830        return 0;
 831}
 832
 833static int __devexit hvcs_remove(struct vio_dev *dev)
 834{
 835        struct hvcs_struct *hvcsd = dev_get_drvdata(&dev->dev);
 836        unsigned long flags;
 837        struct tty_struct *tty;
 838
 839        if (!hvcsd)
 840                return -ENODEV;
 841
 842        /* By this time the vty-server won't be getting any more interrupts */
 843
 844        spin_lock_irqsave(&hvcsd->lock, flags);
 845
 846        tty = hvcsd->tty;
 847
 848        spin_unlock_irqrestore(&hvcsd->lock, flags);
 849
 850        /*
 851         * Let the last holder of this object cause it to be removed, which
 852         * would probably be tty_hangup below.
 853         */
 854        kref_put(&hvcsd->kref, destroy_hvcs_struct);
 855
 856        /*
 857         * The hangup is a scheduled function which will auto chain call
 858         * hvcs_hangup.  The tty should always be valid at this time unless a
 859         * simultaneous tty close already cleaned up the hvcs_struct.
 860         */
 861        if (tty)
 862                tty_hangup(tty);
 863
 864        printk(KERN_INFO "HVCS: vty-server@%X removed from the"
 865                        " vio bus.\n", dev->unit_address);
 866        return 0;
 867};
 868
 869static struct vio_driver hvcs_vio_driver = {
 870        .id_table       = hvcs_driver_table,
 871        .probe          = hvcs_probe,
 872        .remove         = __devexit_p(hvcs_remove),
 873        .driver         = {
 874                .name   = hvcs_driver_name,
 875                .owner  = THIS_MODULE,
 876        }
 877};
 878
 879/* Only called from hvcs_get_pi please */
 880static void hvcs_set_pi(struct hvcs_partner_info *pi, struct hvcs_struct *hvcsd)
 881{
 882        int clclength;
 883
 884        hvcsd->p_unit_address = pi->unit_address;
 885        hvcsd->p_partition_ID  = pi->partition_ID;
 886        clclength = strlen(&pi->location_code[0]);
 887        if (clclength > HVCS_CLC_LENGTH)
 888                clclength = HVCS_CLC_LENGTH;
 889
 890        /* copy the null-term char too */
 891        strncpy(&hvcsd->p_location_code[0],
 892                        &pi->location_code[0], clclength + 1);
 893}
 894
 895/*
 896 * Traverse the list and add the partner info that is found to the hvcs_struct
 897 * struct entry. NOTE: At this time I know that partner info will return a
 898 * single entry but in the future there may be multiple partner info entries per
 899 * vty-server and you'll want to zero out that list and reset it.  If for some
 900 * reason you have an old version of this driver but there IS more than one
 901 * partner info then hvcsd->p_* will hold the last partner info data from the
 902 * firmware query.  A good way to update this code would be to replace the three
 903 * partner info fields in hvcs_struct with a list of hvcs_partner_info
 904 * instances.
 905 *
 906 * This function must be called with the hvcsd->lock held.
 907 */
 908static int hvcs_get_pi(struct hvcs_struct *hvcsd)
 909{
 910        struct hvcs_partner_info *pi;
 911        uint32_t unit_address = hvcsd->vdev->unit_address;
 912        struct list_head head;
 913        int retval;
 914
 915        spin_lock(&hvcs_pi_lock);
 916        if (!hvcs_pi_buff) {
 917                spin_unlock(&hvcs_pi_lock);
 918                return -EFAULT;
 919        }
 920        retval = hvcs_get_partner_info(unit_address, &head, hvcs_pi_buff);
 921        spin_unlock(&hvcs_pi_lock);
 922        if (retval) {
 923                printk(KERN_ERR "HVCS: Failed to fetch partner"
 924                        " info for vty-server@%x.\n", unit_address);
 925                return retval;
 926        }
 927
 928        /* nixes the values if the partner vty went away */
 929        hvcsd->p_unit_address = 0;
 930        hvcsd->p_partition_ID = 0;
 931
 932        list_for_each_entry(pi, &head, node)
 933                hvcs_set_pi(pi, hvcsd);
 934
 935        hvcs_free_partner_info(&head);
 936        return 0;
 937}
 938
 939/*
 940 * This function is executed by the driver "rescan" sysfs entry.  It shouldn't
 941 * be executed elsewhere, in order to prevent deadlock issues.
 942 */
 943static int hvcs_rescan_devices_list(void)
 944{
 945        struct hvcs_struct *hvcsd;
 946        unsigned long flags;
 947
 948        spin_lock(&hvcs_structs_lock);
 949
 950        list_for_each_entry(hvcsd, &hvcs_structs, next) {
 951                spin_lock_irqsave(&hvcsd->lock, flags);
 952                hvcs_get_pi(hvcsd);
 953                spin_unlock_irqrestore(&hvcsd->lock, flags);
 954        }
 955
 956        spin_unlock(&hvcs_structs_lock);
 957
 958        return 0;
 959}
 960
 961/*
 962 * Farm this off into its own function because it could be more complex once
 963 * multiple partners support is added. This function should be called with
 964 * the hvcsd->lock held.
 965 */
 966static int hvcs_has_pi(struct hvcs_struct *hvcsd)
 967{
 968        if ((!hvcsd->p_unit_address) || (!hvcsd->p_partition_ID))
 969                return 0;
 970        return 1;
 971}
 972
 973/*
 974 * NOTE: It is possible that the super admin removed a partner vty and then
 975 * added a different vty as the new partner.
 976 *
 977 * This function must be called with the hvcsd->lock held.
 978 */
 979static int hvcs_partner_connect(struct hvcs_struct *hvcsd)
 980{
 981        int retval;
 982        unsigned int unit_address = hvcsd->vdev->unit_address;
 983
 984        /*
 985         * If there wasn't any pi when the device was added it doesn't meant
 986         * there isn't any now.  This driver isn't notified when a new partner
 987         * vty is added to a vty-server so we discover changes on our own.
 988         * Please see comments in hvcs_register_connection() for justification
 989         * of this bizarre code.
 990         */
 991        retval = hvcs_register_connection(unit_address,
 992                        hvcsd->p_partition_ID,
 993                        hvcsd->p_unit_address);
 994        if (!retval) {
 995                hvcsd->connected = 1;
 996                return 0;
 997        } else if (retval != -EINVAL)
 998                return retval;
 999
1000        /*
1001         * As per the spec re-get the pi and try again if -EINVAL after the
1002         * first connection attempt.
1003         */
1004        if (hvcs_get_pi(hvcsd))
1005                return -ENOMEM;
1006
1007        if (!hvcs_has_pi(hvcsd))
1008                return -ENODEV;
1009
1010        retval = hvcs_register_connection(unit_address,
1011                        hvcsd->p_partition_ID,
1012                        hvcsd->p_unit_address);
1013        if (retval != -EINVAL) {
1014                hvcsd->connected = 1;
1015                return retval;
1016        }
1017
1018        /*
1019         * EBUSY is the most likely scenario though the vty could have been
1020         * removed or there really could be an hcall error due to the parameter
1021         * data but thanks to ambiguous firmware return codes we can't really
1022         * tell.
1023         */
1024        printk(KERN_INFO "HVCS: vty-server or partner"
1025                        " vty is busy.  Try again later.\n");
1026        return -EBUSY;
1027}
1028
1029/* This function must be called with the hvcsd->lock held */
1030static void hvcs_partner_free(struct hvcs_struct *hvcsd)
1031{
1032        int retval;
1033        do {
1034                retval = hvcs_free_connection(hvcsd->vdev->unit_address);
1035        } while (retval == -EBUSY);
1036        hvcsd->connected = 0;
1037}
1038
1039/* This helper function must be called WITHOUT the hvcsd->lock held */
1040static int hvcs_enable_device(struct hvcs_struct *hvcsd, uint32_t unit_address,
1041                unsigned int irq, struct vio_dev *vdev)
1042{
1043        unsigned long flags;
1044        int rc;
1045
1046        /*
1047         * It is possible that the vty-server was removed between the time that
1048         * the conn was registered and now.
1049         */
1050        if (!(rc = request_irq(irq, &hvcs_handle_interrupt,
1051                                IRQF_DISABLED, "ibmhvcs", hvcsd))) {
1052                /*
1053                 * It is possible the vty-server was removed after the irq was
1054                 * requested but before we have time to enable interrupts.
1055                 */
1056                if (vio_enable_interrupts(vdev) == H_SUCCESS)
1057                        return 0;
1058                else {
1059                        printk(KERN_ERR "HVCS: int enable failed for"
1060                                        " vty-server@%X.\n", unit_address);
1061                        free_irq(irq, hvcsd);
1062                }
1063        } else
1064                printk(KERN_ERR "HVCS: irq req failed for"
1065                                " vty-server@%X.\n", unit_address);
1066
1067        spin_lock_irqsave(&hvcsd->lock, flags);
1068        hvcs_partner_free(hvcsd);
1069        spin_unlock_irqrestore(&hvcsd->lock, flags);
1070
1071        return rc;
1072
1073}
1074
1075/*
1076 * This always increments the kref ref count if the call is successful.
1077 * Please remember to dec when you are done with the instance.
1078 *
1079 * NOTICE: Do NOT hold either the hvcs_struct.lock or hvcs_structs_lock when
1080 * calling this function or you will get deadlock.
1081 */
1082static struct hvcs_struct *hvcs_get_by_index(int index)
1083{
1084        struct hvcs_struct *hvcsd = NULL;
1085        unsigned long flags;
1086
1087        spin_lock(&hvcs_structs_lock);
1088        /* We can immediately discard OOB requests */
1089        if (index >= 0 && index < HVCS_MAX_SERVER_ADAPTERS) {
1090                list_for_each_entry(hvcsd, &hvcs_structs, next) {
1091                        spin_lock_irqsave(&hvcsd->lock, flags);
1092                        if (hvcsd->index == index) {
1093                                kref_get(&hvcsd->kref);
1094                                spin_unlock_irqrestore(&hvcsd->lock, flags);
1095                                spin_unlock(&hvcs_structs_lock);
1096                                return hvcsd;
1097                        }
1098                        spin_unlock_irqrestore(&hvcsd->lock, flags);
1099                }
1100                hvcsd = NULL;
1101        }
1102
1103        spin_unlock(&hvcs_structs_lock);
1104        return hvcsd;
1105}
1106
1107/*
1108 * This is invoked via the tty_open interface when a user app connects to the
1109 * /dev node.
1110 */
1111static int hvcs_open(struct tty_struct *tty, struct file *filp)
1112{
1113        struct hvcs_struct *hvcsd;
1114        int rc, retval = 0;
1115        unsigned long flags;
1116        unsigned int irq;
1117        struct vio_dev *vdev;
1118        unsigned long unit_address;
1119
1120        if (tty->driver_data)
1121                goto fast_open;
1122
1123        /*
1124         * Is there a vty-server that shares the same index?
1125         * This function increments the kref index.
1126         */
1127        if (!(hvcsd = hvcs_get_by_index(tty->index))) {
1128                printk(KERN_WARNING "HVCS: open failed, no device associated"
1129                                " with tty->index %d.\n", tty->index);
1130                return -ENODEV;
1131        }
1132
1133        spin_lock_irqsave(&hvcsd->lock, flags);
1134
1135        if (hvcsd->connected == 0)
1136                if ((retval = hvcs_partner_connect(hvcsd)))
1137                        goto error_release;
1138
1139        hvcsd->open_count = 1;
1140        hvcsd->tty = tty;
1141        tty->driver_data = hvcsd;
1142
1143        memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1144
1145        /*
1146         * Save these in the spinlock for the enable operations that need them
1147         * outside of the spinlock.
1148         */
1149        irq = hvcsd->vdev->irq;
1150        vdev = hvcsd->vdev;
1151        unit_address = hvcsd->vdev->unit_address;
1152
1153        hvcsd->todo_mask |= HVCS_SCHED_READ;
1154        spin_unlock_irqrestore(&hvcsd->lock, flags);
1155
1156        /*
1157         * This must be done outside of the spinlock because it requests irqs
1158         * and will grab the spinlock and free the connection if it fails.
1159         */
1160        if (((rc = hvcs_enable_device(hvcsd, unit_address, irq, vdev)))) {
1161                kref_put(&hvcsd->kref, destroy_hvcs_struct);
1162                printk(KERN_WARNING "HVCS: enable device failed.\n");
1163                return rc;
1164        }
1165
1166        goto open_success;
1167
1168fast_open:
1169        hvcsd = tty->driver_data;
1170
1171        spin_lock_irqsave(&hvcsd->lock, flags);
1172        kref_get(&hvcsd->kref);
1173        hvcsd->open_count++;
1174        hvcsd->todo_mask |= HVCS_SCHED_READ;
1175        spin_unlock_irqrestore(&hvcsd->lock, flags);
1176
1177open_success:
1178        hvcs_kick();
1179
1180        printk(KERN_INFO "HVCS: vty-server@%X connection opened.\n",
1181                hvcsd->vdev->unit_address );
1182
1183        return 0;
1184
1185error_release:
1186        spin_unlock_irqrestore(&hvcsd->lock, flags);
1187        kref_put(&hvcsd->kref, destroy_hvcs_struct);
1188
1189        printk(KERN_WARNING "HVCS: partner connect failed.\n");
1190        return retval;
1191}
1192
1193static void hvcs_close(struct tty_struct *tty, struct file *filp)
1194{
1195        struct hvcs_struct *hvcsd;
1196        unsigned long flags;
1197        int irq = NO_IRQ;
1198
1199        /*
1200         * Is someone trying to close the file associated with this device after
1201         * we have hung up?  If so tty->driver_data wouldn't be valid.
1202         */
1203        if (tty_hung_up_p(filp))
1204                return;
1205
1206        /*
1207         * No driver_data means that this close was probably issued after a
1208         * failed hvcs_open by the tty layer's release_dev() api and we can just
1209         * exit cleanly.
1210         */
1211        if (!tty->driver_data)
1212                return;
1213
1214        hvcsd = tty->driver_data;
1215
1216        spin_lock_irqsave(&hvcsd->lock, flags);
1217        if (--hvcsd->open_count == 0) {
1218
1219                vio_disable_interrupts(hvcsd->vdev);
1220
1221                /*
1222                 * NULL this early so that the kernel_thread doesn't try to
1223                 * execute any operations on the TTY even though it is obligated
1224                 * to deliver any pending I/O to the hypervisor.
1225                 */
1226                hvcsd->tty = NULL;
1227
1228                irq = hvcsd->vdev->irq;
1229                spin_unlock_irqrestore(&hvcsd->lock, flags);
1230
1231                tty_wait_until_sent(tty, HVCS_CLOSE_WAIT);
1232
1233                /*
1234                 * This line is important because it tells hvcs_open that this
1235                 * device needs to be re-configured the next time hvcs_open is
1236                 * called.
1237                 */
1238                tty->driver_data = NULL;
1239
1240                free_irq(irq, hvcsd);
1241                kref_put(&hvcsd->kref, destroy_hvcs_struct);
1242                return;
1243        } else if (hvcsd->open_count < 0) {
1244                printk(KERN_ERR "HVCS: vty-server@%X open_count: %d"
1245                                " is missmanaged.\n",
1246                hvcsd->vdev->unit_address, hvcsd->open_count);
1247        }
1248
1249        spin_unlock_irqrestore(&hvcsd->lock, flags);
1250        kref_put(&hvcsd->kref, destroy_hvcs_struct);
1251}
1252
1253static void hvcs_hangup(struct tty_struct * tty)
1254{
1255        struct hvcs_struct *hvcsd = tty->driver_data;
1256        unsigned long flags;
1257        int temp_open_count;
1258        int irq = NO_IRQ;
1259
1260        spin_lock_irqsave(&hvcsd->lock, flags);
1261        /* Preserve this so that we know how many kref refs to put */
1262        temp_open_count = hvcsd->open_count;
1263
1264        /*
1265         * Don't kref put inside the spinlock because the destruction
1266         * callback may use the spinlock and it may get called before the
1267         * spinlock has been released.
1268         */
1269        vio_disable_interrupts(hvcsd->vdev);
1270
1271        hvcsd->todo_mask = 0;
1272
1273        /* I don't think the tty needs the hvcs_struct pointer after a hangup */
1274        hvcsd->tty->driver_data = NULL;
1275        hvcsd->tty = NULL;
1276
1277        hvcsd->open_count = 0;
1278
1279        /* This will drop any buffered data on the floor which is OK in a hangup
1280         * scenario. */
1281        memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1282        hvcsd->chars_in_buffer = 0;
1283
1284        irq = hvcsd->vdev->irq;
1285
1286        spin_unlock_irqrestore(&hvcsd->lock, flags);
1287
1288        free_irq(irq, hvcsd);
1289
1290        /*
1291         * We need to kref_put() for every open_count we have since the
1292         * tty_hangup() function doesn't invoke a close per open connection on a
1293         * non-console device.
1294         */
1295        while(temp_open_count) {
1296                --temp_open_count;
1297                /*
1298                 * The final put will trigger destruction of the hvcs_struct.
1299                 * NOTE:  If this hangup was signaled from user space then the
1300                 * final put will never happen.
1301                 */
1302                kref_put(&hvcsd->kref, destroy_hvcs_struct);
1303        }
1304}
1305
1306/*
1307 * NOTE: This is almost always from_user since user level apps interact with the
1308 * /dev nodes. I'm trusting that if hvcs_write gets called and interrupted by
1309 * hvcs_remove (which removes the target device and executes tty_hangup()) that
1310 * tty_hangup will allow hvcs_write time to complete execution before it
1311 * terminates our device.
1312 */
1313static int hvcs_write(struct tty_struct *tty,
1314                const unsigned char *buf, int count)
1315{
1316        struct hvcs_struct *hvcsd = tty->driver_data;
1317        unsigned int unit_address;
1318        const unsigned char *charbuf;
1319        unsigned long flags;
1320        int total_sent = 0;
1321        int tosend = 0;
1322        int result = 0;
1323
1324        /*
1325         * If they don't check the return code off of their open they may
1326         * attempt this even if there is no connected device.
1327         */
1328        if (!hvcsd)
1329                return -ENODEV;
1330
1331        /* Reasonable size to prevent user level flooding */
1332        if (count > HVCS_MAX_FROM_USER) {
1333                printk(KERN_WARNING "HVCS write: count being truncated to"
1334                                " HVCS_MAX_FROM_USER.\n");
1335                count = HVCS_MAX_FROM_USER;
1336        }
1337
1338        charbuf = buf;
1339
1340        spin_lock_irqsave(&hvcsd->lock, flags);
1341
1342        /*
1343         * Somehow an open succedded but the device was removed or the
1344         * connection terminated between the vty-server and partner vty during
1345         * the middle of a write operation?  This is a crummy place to do this
1346         * but we want to keep it all in the spinlock.
1347         */
1348        if (hvcsd->open_count <= 0) {
1349                spin_unlock_irqrestore(&hvcsd->lock, flags);
1350                return -ENODEV;
1351        }
1352
1353        unit_address = hvcsd->vdev->unit_address;
1354
1355        while (count > 0) {
1356                tosend = min(count, (HVCS_BUFF_LEN - hvcsd->chars_in_buffer));
1357                /*
1358                 * No more space, this probably means that the last call to
1359                 * hvcs_write() didn't succeed and the buffer was filled up.
1360                 */
1361                if (!tosend)
1362                        break;
1363
1364                memcpy(&hvcsd->buffer[hvcsd->chars_in_buffer],
1365                                &charbuf[total_sent],
1366                                tosend);
1367
1368                hvcsd->chars_in_buffer += tosend;
1369
1370                result = 0;
1371
1372                /*
1373                 * If this is true then we don't want to try writing to the
1374                 * hypervisor because that is the kernel_threads job now.  We'll
1375                 * just add to the buffer.
1376                 */
1377                if (!(hvcsd->todo_mask & HVCS_TRY_WRITE))
1378                        /* won't send partial writes */
1379                        result = hvc_put_chars(unit_address,
1380                                        &hvcsd->buffer[0],
1381                                        hvcsd->chars_in_buffer);
1382
1383                /*
1384                 * Since we know we have enough room in hvcsd->buffer for
1385                 * tosend we record that it was sent regardless of whether the
1386                 * hypervisor actually took it because we have it buffered.
1387                 */
1388                total_sent+=tosend;
1389                count-=tosend;
1390                if (result == 0) {
1391                        hvcsd->todo_mask |= HVCS_TRY_WRITE;
1392                        hvcs_kick();
1393                        break;
1394                }
1395
1396                hvcsd->chars_in_buffer = 0;
1397                /*
1398                 * Test after the chars_in_buffer reset otherwise this could
1399                 * deadlock our writes if hvc_put_chars fails.
1400                 */
1401                if (result < 0)
1402                        break;
1403        }
1404
1405        spin_unlock_irqrestore(&hvcsd->lock, flags);
1406
1407        if (result == -1)
1408                return -EIO;
1409        else
1410                return total_sent;
1411}
1412
1413/*
1414 * This is really asking how much can we guarentee that we can send or that we
1415 * absolutely WILL BUFFER if we can't send it.  This driver MUST honor the
1416 * return value, hence the reason for hvcs_struct buffering.
1417 */
1418static int hvcs_write_room(struct tty_struct *tty)
1419{
1420        struct hvcs_struct *hvcsd = tty->driver_data;
1421
1422        if (!hvcsd || hvcsd->open_count <= 0)
1423                return 0;
1424
1425        return HVCS_BUFF_LEN - hvcsd->chars_in_buffer;
1426}
1427
1428static int hvcs_chars_in_buffer(struct tty_struct *tty)
1429{
1430        struct hvcs_struct *hvcsd = tty->driver_data;
1431
1432        return hvcsd->chars_in_buffer;
1433}
1434
1435static const struct tty_operations hvcs_ops = {
1436        .open = hvcs_open,
1437        .close = hvcs_close,
1438        .hangup = hvcs_hangup,
1439        .write = hvcs_write,
1440        .write_room = hvcs_write_room,
1441        .chars_in_buffer = hvcs_chars_in_buffer,
1442        .unthrottle = hvcs_unthrottle,
1443        .throttle = hvcs_throttle,
1444};
1445
1446static int hvcs_alloc_index_list(int n)
1447{
1448        int i;
1449
1450        hvcs_index_list = kmalloc(n * sizeof(hvcs_index_count),GFP_KERNEL);
1451        if (!hvcs_index_list)
1452                return -ENOMEM;
1453        hvcs_index_count = n;
1454        for (i = 0; i < hvcs_index_count; i++)
1455                hvcs_index_list[i] = -1;
1456        return 0;
1457}
1458
1459static void hvcs_free_index_list(void)
1460{
1461        /* Paranoia check to be thorough. */
1462        kfree(hvcs_index_list);
1463        hvcs_index_list = NULL;
1464        hvcs_index_count = 0;
1465}
1466
1467static int __init hvcs_module_init(void)
1468{
1469        int rc;
1470        int num_ttys_to_alloc;
1471
1472        printk(KERN_INFO "Initializing %s\n", hvcs_driver_string);
1473
1474        /* Has the user specified an overload with an insmod param? */
1475        if (hvcs_parm_num_devs <= 0 ||
1476                (hvcs_parm_num_devs > HVCS_MAX_SERVER_ADAPTERS)) {
1477                num_ttys_to_alloc = HVCS_DEFAULT_SERVER_ADAPTERS;
1478        } else
1479                num_ttys_to_alloc = hvcs_parm_num_devs;
1480
1481        hvcs_tty_driver = alloc_tty_driver(num_ttys_to_alloc);
1482        if (!hvcs_tty_driver)
1483                return -ENOMEM;
1484
1485        if (hvcs_alloc_index_list(num_ttys_to_alloc)) {
1486                rc = -ENOMEM;
1487                goto index_fail;
1488        }
1489
1490        hvcs_tty_driver->owner = THIS_MODULE;
1491
1492        hvcs_tty_driver->driver_name = hvcs_driver_name;
1493        hvcs_tty_driver->name = hvcs_device_node;
1494
1495        /*
1496         * We'll let the system assign us a major number, indicated by leaving
1497         * it blank.
1498         */
1499
1500        hvcs_tty_driver->minor_start = HVCS_MINOR_START;
1501        hvcs_tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
1502
1503        /*
1504         * We role our own so that we DONT ECHO.  We can't echo because the
1505         * device we are connecting to already echoes by default and this would
1506         * throw us into a horrible recursive echo-echo-echo loop.
1507         */
1508        hvcs_tty_driver->init_termios = hvcs_tty_termios;
1509        hvcs_tty_driver->flags = TTY_DRIVER_REAL_RAW;
1510
1511        tty_set_operations(hvcs_tty_driver, &hvcs_ops);
1512
1513        /*
1514         * The following call will result in sysfs entries that denote the
1515         * dynamically assigned major and minor numbers for our devices.
1516         */
1517        if (tty_register_driver(hvcs_tty_driver)) {
1518                printk(KERN_ERR "HVCS: registration as a tty driver failed.\n");
1519                rc = -EIO;
1520                goto register_fail;
1521        }
1522
1523        hvcs_pi_buff = kmalloc(PAGE_SIZE, GFP_KERNEL);
1524        if (!hvcs_pi_buff) {
1525                rc = -ENOMEM;
1526                goto buff_alloc_fail;
1527        }
1528
1529        hvcs_task = kthread_run(khvcsd, NULL, "khvcsd");
1530        if (IS_ERR(hvcs_task)) {
1531                printk(KERN_ERR "HVCS: khvcsd creation failed.  Driver not loaded.\n");
1532                rc = -EIO;
1533                goto kthread_fail;
1534        }
1535
1536        rc = vio_register_driver(&hvcs_vio_driver);
1537        if (rc) {
1538                printk(KERN_ERR "HVCS: can't register vio driver\n");
1539                goto vio_fail;
1540        }
1541
1542        /*
1543         * This needs to be done AFTER the vio_register_driver() call or else
1544         * the kobjects won't be initialized properly.
1545         */
1546        rc = driver_create_file(&(hvcs_vio_driver.driver), &driver_attr_rescan);
1547        if (rc) {
1548                printk(KERN_ERR "HVCS: sysfs attr create failed\n");
1549                goto attr_fail;
1550        }
1551
1552        printk(KERN_INFO "HVCS: driver module inserted.\n");
1553
1554        return 0;
1555
1556attr_fail:
1557        vio_unregister_driver(&hvcs_vio_driver);
1558vio_fail:
1559        kthread_stop(hvcs_task);
1560kthread_fail:
1561        kfree(hvcs_pi_buff);
1562buff_alloc_fail:
1563        tty_unregister_driver(hvcs_tty_driver);
1564register_fail:
1565        hvcs_free_index_list();
1566index_fail:
1567        put_tty_driver(hvcs_tty_driver);
1568        hvcs_tty_driver = NULL;
1569        return rc;
1570}
1571
1572static void __exit hvcs_module_exit(void)
1573{
1574        /*
1575         * This driver receives hvcs_remove callbacks for each device upon
1576         * module removal.
1577         */
1578
1579        /*
1580         * This synchronous operation  will wake the khvcsd kthread if it is
1581         * asleep and will return when khvcsd has terminated.
1582         */
1583        kthread_stop(hvcs_task);
1584
1585        spin_lock(&hvcs_pi_lock);
1586        kfree(hvcs_pi_buff);
1587        hvcs_pi_buff = NULL;
1588        spin_unlock(&hvcs_pi_lock);
1589
1590        driver_remove_file(&hvcs_vio_driver.driver, &driver_attr_rescan);
1591
1592        vio_unregister_driver(&hvcs_vio_driver);
1593
1594        tty_unregister_driver(hvcs_tty_driver);
1595
1596        hvcs_free_index_list();
1597
1598        put_tty_driver(hvcs_tty_driver);
1599
1600        printk(KERN_INFO "HVCS: driver module removed.\n");
1601}
1602
1603module_init(hvcs_module_init);
1604module_exit(hvcs_module_exit);
1605
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