err.no Git - linux-2.6/blob - drivers/s390/block/dcssblk.c

   1 /*
   2  * dcssblk.c -- the S/390 block driver for dcss memory
   3  *
   4  * Authors: Carsten Otte, Stefan Weinhuber, Gerald Schaefer
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/moduleparam.h>
   9 #include <linux/ctype.h>
  10 #include <linux/errno.h>
  11 #include <linux/init.h>
  12 #include <linux/slab.h>
  13 #include <linux/blkdev.h>
  14 #include <asm/extmem.h>
  15 #include <asm/io.h>
  16 #include <linux/completion.h>
  17 #include <linux/interrupt.h>
  18 #include <asm/s390_rdev.h>
  19
  20 //#define DCSSBLK_DEBUG         /* Debug messages on/off */
  21 #define DCSSBLK_NAME "dcssblk"
  22 #define DCSSBLK_MINORS_PER_DISK 1
  23 #define DCSSBLK_PARM_LEN 400
  24
  25 #ifdef DCSSBLK_DEBUG
  26 #define PRINT_DEBUG(x...) printk(KERN_DEBUG DCSSBLK_NAME " debug: " x)
  27 #else
  28 #define PRINT_DEBUG(x...) do {} while (0)
  29 #endif
  30 #define PRINT_INFO(x...)  printk(KERN_INFO DCSSBLK_NAME " info: " x)
  31 #define PRINT_WARN(x...)  printk(KERN_WARNING DCSSBLK_NAME " warning: " x)
  32 #define PRINT_ERR(x...)   printk(KERN_ERR DCSSBLK_NAME " error: " x)
  33
  34
  35 static int dcssblk_open(struct inode *inode, struct file *filp);
  36 static int dcssblk_release(struct inode *inode, struct file *filp);
  37 static int dcssblk_make_request(struct request_queue *q, struct bio *bio);
  38 static int dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
  39                                  void **kaddr, unsigned long *pfn);
  40
  41 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
  42
  43 static int dcssblk_major;
  44 static struct block_device_operations dcssblk_devops = {
  45         .owner          = THIS_MODULE,
  46         .open           = dcssblk_open,
  47         .release        = dcssblk_release,
  48         .direct_access  = dcssblk_direct_access,
  49 };
  50
  51 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  52                                   size_t count);
  53 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  54                                   size_t count);
  55 static ssize_t dcssblk_save_store(struct device * dev, struct device_attribute *attr, const char * buf,
  56                                   size_t count);
  57 static ssize_t dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf);
  58 static ssize_t dcssblk_shared_store(struct device * dev, struct device_attribute *attr, const char * buf,
  59                                   size_t count);
  60 static ssize_t dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf);
  61
  62 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  63 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  64 static DEVICE_ATTR(save, S_IWUSR | S_IRUGO, dcssblk_save_show,
  65                    dcssblk_save_store);
  66 static DEVICE_ATTR(shared, S_IWUSR | S_IRUGO, dcssblk_shared_show,
  67                    dcssblk_shared_store);
  68
  69 static struct device *dcssblk_root_dev;
  70
  71 struct dcssblk_dev_info {
  72         struct list_head lh;
  73         struct device dev;
  74         char segment_name[BUS_ID_SIZE];
  75         atomic_t use_count;
  76         struct gendisk *gd;
  77         unsigned long start;
  78         unsigned long end;
  79         int segment_type;
  80         unsigned char save_pending;
  81         unsigned char is_shared;
  82         struct request_queue *dcssblk_queue;
  83 };
  84
  85 static LIST_HEAD(dcssblk_devices);
  86 static struct rw_semaphore dcssblk_devices_sem;
  87
  88 /*
  89  * release function for segment device.
  90  */
  91 static void
  92 dcssblk_release_segment(struct device *dev)
  93 {
  94         PRINT_DEBUG("segment release fn called for %s\n", dev->bus_id);
  95         kfree(container_of(dev, struct dcssblk_dev_info, dev));
  96         module_put(THIS_MODULE);
  97 }
  98
  99 /*
 100  * get a minor number. needs to be called with
 101  * down_write(&dcssblk_devices_sem) and the
 102  * device needs to be enqueued before the semaphore is
 103  * freed.
 104  */
 105 static int
 106 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 107 {
 108         int minor, found;
 109         struct dcssblk_dev_info *entry;
 110
 111         if (dev_info == NULL)
 112                 return -EINVAL;
 113         for (minor = 0; minor < (1<<MINORBITS); minor++) {
 114                 found = 0;
 115                 // test if minor available
 116                 list_for_each_entry(entry, &dcssblk_devices, lh)
 117                         if (minor == entry->gd->first_minor)
 118                                 found++;
 119                 if (!found) break; // got unused minor
 120         }
 121         if (found)
 122                 return -EBUSY;
 123         dev_info->gd->first_minor = minor;
 124         return 0;
 125 }
 126
 127 /*
 128  * get the struct dcssblk_dev_info from dcssblk_devices
 129  * for the given name.
 130  * down_read(&dcssblk_devices_sem) must be held.
 131  */
 132 static struct dcssblk_dev_info *
 133 dcssblk_get_device_by_name(char *name)
 134 {
 135         struct dcssblk_dev_info *entry;
 136
 137         list_for_each_entry(entry, &dcssblk_devices, lh) {
 138                 if (!strcmp(name, entry->segment_name)) {
 139                         return entry;
 140                 }
 141         }
 142         return NULL;
 143 }
 144
 145 static void dcssblk_unregister_callback(struct device *dev)
 146 {
 147         device_unregister(dev);
 148         put_device(dev);
 149 }
 150
 151 /*
 152  * device attribute for switching shared/nonshared (exclusive)
 153  * operation (show + store)
 154  */
 155 static ssize_t
 156 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 157 {
 158         struct dcssblk_dev_info *dev_info;
 159
 160         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 161         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 162 }
 163
 164 static ssize_t
 165 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 166 {
 167         struct dcssblk_dev_info *dev_info;
 168         int rc;
 169
 170         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 171                 return -EINVAL;
 172         down_write(&dcssblk_devices_sem);
 173         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 174         if (atomic_read(&dev_info->use_count)) {
 175                 PRINT_ERR("share: segment %s is busy!\n",
 176                           dev_info->segment_name);
 177                 rc = -EBUSY;
 178                 goto out;
 179         }
 180         if (inbuf[0] == '1') {
 181                 // reload segment in shared mode
 182                 rc = segment_modify_shared(dev_info->segment_name,
 183                                            SEGMENT_SHARED);
 184                 if (rc < 0) {
 185                         BUG_ON(rc == -EINVAL);
 186                         if (rc != -EAGAIN)
 187                                 goto removeseg;
 188                 } else {
 189                         dev_info->is_shared = 1;
 190                         switch (dev_info->segment_type) {
 191                                 case SEG_TYPE_SR:
 192                                 case SEG_TYPE_ER:
 193                                 case SEG_TYPE_SC:
 194                                         set_disk_ro(dev_info->gd,1);
 195                         }
 196                 }
 197         } else if (inbuf[0] == '0') {
 198                 // reload segment in exclusive mode
 199                 if (dev_info->segment_type == SEG_TYPE_SC) {
 200                         PRINT_ERR("Segment type SC (%s) cannot be loaded in "
 201                                   "non-shared mode\n", dev_info->segment_name);
 202                         rc = -EINVAL;
 203                         goto out;
 204                 }
 205                 rc = segment_modify_shared(dev_info->segment_name,
 206                                            SEGMENT_EXCLUSIVE);
 207                 if (rc < 0) {
 208                         BUG_ON(rc == -EINVAL);
 209                         if (rc != -EAGAIN)
 210                                 goto removeseg;
 211                 } else {
 212                         dev_info->is_shared = 0;
 213                         set_disk_ro(dev_info->gd, 0);
 214                 }
 215         } else {
 216                 rc = -EINVAL;
 217                 goto out;
 218         }
 219         rc = count;
 220         goto out;
 221
 222 removeseg:
 223         PRINT_ERR("Could not reload segment %s, removing it now!\n",
 224                         dev_info->segment_name);
 225         list_del(&dev_info->lh);
 226
 227         del_gendisk(dev_info->gd);
 228         blk_cleanup_queue(dev_info->dcssblk_queue);
 229         dev_info->gd->queue = NULL;
 230         put_disk(dev_info->gd);
 231         rc = device_schedule_callback(dev, dcssblk_unregister_callback);
 232 out:
 233         up_write(&dcssblk_devices_sem);
 234         return rc;
 235 }
 236
 237 /*
 238  * device attribute for save operation on current copy
 239  * of the segment. If the segment is busy, saving will
 240  * become pending until it gets released, which can be
 241  * undone by storing a non-true value to this entry.
 242  * (show + store)
 243  */
 244 static ssize_t
 245 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 246 {
 247         struct dcssblk_dev_info *dev_info;
 248
 249         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 250         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 251 }
 252
 253 static ssize_t
 254 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 255 {
 256         struct dcssblk_dev_info *dev_info;
 257
 258         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 259                 return -EINVAL;
 260         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 261
 262         down_write(&dcssblk_devices_sem);
 263         if (inbuf[0] == '1') {
 264                 if (atomic_read(&dev_info->use_count) == 0) {
 265                         // device is idle => we save immediately
 266                         PRINT_INFO("Saving segment %s\n",
 267                                    dev_info->segment_name);
 268                         segment_save(dev_info->segment_name);
 269                 }  else {
 270                         // device is busy => we save it when it becomes
 271                         // idle in dcssblk_release
 272                         PRINT_INFO("Segment %s is currently busy, it will "
 273                                    "be saved when it becomes idle...\n",
 274                                    dev_info->segment_name);
 275                         dev_info->save_pending = 1;
 276                 }
 277         } else if (inbuf[0] == '0') {
 278                 if (dev_info->save_pending) {
 279                         // device is busy & the user wants to undo his save
 280                         // request
 281                         dev_info->save_pending = 0;
 282                         PRINT_INFO("Pending save for segment %s deactivated\n",
 283                                         dev_info->segment_name);
 284                 }
 285         } else {
 286                 up_write(&dcssblk_devices_sem);
 287                 return -EINVAL;
 288         }
 289         up_write(&dcssblk_devices_sem);
 290         return count;
 291 }
 292
 293 /*
 294  * device attribute for adding devices
 295  */
 296 static ssize_t
 297 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 298 {
 299         int rc, i;
 300         struct dcssblk_dev_info *dev_info;
 301         char *local_buf;
 302         unsigned long seg_byte_size;
 303
 304         dev_info = NULL;
 305         if (dev != dcssblk_root_dev) {
 306                 rc = -EINVAL;
 307                 goto out_nobuf;
 308         }
 309         local_buf = kmalloc(count + 1, GFP_KERNEL);
 310         if (local_buf == NULL) {
 311                 rc = -ENOMEM;
 312                 goto out_nobuf;
 313         }
 314         /*
 315          * parse input
 316          */
 317         for (i = 0; ((buf[i] != '\0') && (buf[i] != '\n') && i < count); i++) {
 318                 local_buf[i] = toupper(buf[i]);
 319         }
 320         local_buf[i] = '\0';
 321         if ((i == 0) || (i > 8)) {
 322                 rc = -ENAMETOOLONG;
 323                 goto out;
 324         }
 325         /*
 326          * already loaded?
 327          */
 328         down_read(&dcssblk_devices_sem);
 329         dev_info = dcssblk_get_device_by_name(local_buf);
 330         up_read(&dcssblk_devices_sem);
 331         if (dev_info != NULL) {
 332                 PRINT_WARN("Segment %s already loaded!\n", local_buf);
 333                 rc = -EEXIST;
 334                 goto out;
 335         }
 336         /*
 337          * get a struct dcssblk_dev_info
 338          */
 339         dev_info = kzalloc(sizeof(struct dcssblk_dev_info), GFP_KERNEL);
 340         if (dev_info == NULL) {
 341                 rc = -ENOMEM;
 342                 goto out;
 343         }
 344
 345         strcpy(dev_info->segment_name, local_buf);
 346         strlcpy(dev_info->dev.bus_id, local_buf, BUS_ID_SIZE);
 347         dev_info->dev.release = dcssblk_release_segment;
 348         INIT_LIST_HEAD(&dev_info->lh);
 349
 350         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 351         if (dev_info->gd == NULL) {
 352                 rc = -ENOMEM;
 353                 goto free_dev_info;
 354         }
 355         dev_info->gd->major = dcssblk_major;
 356         dev_info->gd->fops = &dcssblk_devops;
 357         dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 358         dev_info->gd->queue = dev_info->dcssblk_queue;
 359         dev_info->gd->private_data = dev_info;
 360         dev_info->gd->driverfs_dev = &dev_info->dev;
 361         blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 362         blk_queue_hardsect_size(dev_info->dcssblk_queue, 4096);
 363         /*
 364          * load the segment
 365          */
 366         rc = segment_load(local_buf, SEGMENT_SHARED,
 367                                 &dev_info->start, &dev_info->end);
 368         if (rc < 0) {
 369                 segment_warning(rc, dev_info->segment_name);
 370                 goto dealloc_gendisk;
 371         }
 372         seg_byte_size = (dev_info->end - dev_info->start + 1);
 373         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 374         PRINT_INFO("Loaded segment %s, size = %lu Byte, "
 375                    "capacity = %lu (512 Byte) sectors\n", local_buf,
 376                    seg_byte_size, seg_byte_size >> 9);
 377
 378         dev_info->segment_type = rc;
 379         dev_info->save_pending = 0;
 380         dev_info->is_shared = 1;
 381         dev_info->dev.parent = dcssblk_root_dev;
 382
 383         /*
 384          * get minor, add to list
 385          */
 386         down_write(&dcssblk_devices_sem);
 387         if (dcssblk_get_device_by_name(local_buf)) {
 388                 up_write(&dcssblk_devices_sem);
 389                 rc = -EEXIST;
 390                 goto unload_seg;
 391         }
 392         rc = dcssblk_assign_free_minor(dev_info);
 393         if (rc) {
 394                 up_write(&dcssblk_devices_sem);
 395                 PRINT_ERR("No free minor number available! "
 396                           "Unloading segment...\n");
 397                 goto unload_seg;
 398         }
 399         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 400                 dev_info->gd->first_minor);
 401         list_add_tail(&dev_info->lh, &dcssblk_devices);
 402
 403         if (!try_module_get(THIS_MODULE)) {
 404                 rc = -ENODEV;
 405                 goto list_del;
 406         }
 407         /*
 408          * register the device
 409          */
 410         rc = device_register(&dev_info->dev);
 411         if (rc) {
 412                 PRINT_ERR("Segment %s could not be registered RC=%d\n",
 413                                 local_buf, rc);
 414                 module_put(THIS_MODULE);
 415                 goto list_del;
 416         }
 417         get_device(&dev_info->dev);
 418         rc = device_create_file(&dev_info->dev, &dev_attr_shared);
 419         if (rc)
 420                 goto unregister_dev;
 421         rc = device_create_file(&dev_info->dev, &dev_attr_save);
 422         if (rc)
 423                 goto unregister_dev;
 424
 425         add_disk(dev_info->gd);
 426
 427         switch (dev_info->segment_type) {
 428                 case SEG_TYPE_SR:
 429                 case SEG_TYPE_ER:
 430                 case SEG_TYPE_SC:
 431                         set_disk_ro(dev_info->gd,1);
 432                         break;
 433                 default:
 434                         set_disk_ro(dev_info->gd,0);
 435                         break;
 436         }
 437         PRINT_DEBUG("Segment %s loaded successfully\n", local_buf);
 438         up_write(&dcssblk_devices_sem);
 439         rc = count;
 440         goto out;
 441
 442 unregister_dev:
 443         list_del(&dev_info->lh);
 444         blk_cleanup_queue(dev_info->dcssblk_queue);
 445         dev_info->gd->queue = NULL;
 446         put_disk(dev_info->gd);
 447         device_unregister(&dev_info->dev);
 448         segment_unload(dev_info->segment_name);
 449         put_device(&dev_info->dev);
 450         up_write(&dcssblk_devices_sem);
 451         goto out;
 452 list_del:
 453         list_del(&dev_info->lh);
 454         up_write(&dcssblk_devices_sem);
 455 unload_seg:
 456         segment_unload(local_buf);
 457 dealloc_gendisk:
 458         blk_cleanup_queue(dev_info->dcssblk_queue);
 459         dev_info->gd->queue = NULL;
 460         put_disk(dev_info->gd);
 461 free_dev_info:
 462         kfree(dev_info);
 463 out:
 464         kfree(local_buf);
 465 out_nobuf:
 466         return rc;
 467 }
 468
 469 /*
 470  * device attribute for removing devices
 471  */
 472 static ssize_t
 473 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 474 {
 475         struct dcssblk_dev_info *dev_info;
 476         int rc, i;
 477         char *local_buf;
 478
 479         if (dev != dcssblk_root_dev) {
 480                 return -EINVAL;
 481         }
 482         local_buf = kmalloc(count + 1, GFP_KERNEL);
 483         if (local_buf == NULL) {
 484                 return -ENOMEM;
 485         }
 486         /*
 487          * parse input
 488          */
 489         for (i = 0; ((*(buf+i)!='\0') && (*(buf+i)!='\n') && i < count); i++) {
 490                 local_buf[i] = toupper(buf[i]);
 491         }
 492         local_buf[i] = '\0';
 493         if ((i == 0) || (i > 8)) {
 494                 rc = -ENAMETOOLONG;
 495                 goto out_buf;
 496         }
 497
 498         down_write(&dcssblk_devices_sem);
 499         dev_info = dcssblk_get_device_by_name(local_buf);
 500         if (dev_info == NULL) {
 501                 up_write(&dcssblk_devices_sem);
 502                 PRINT_WARN("Segment %s is not loaded!\n", local_buf);
 503                 rc = -ENODEV;
 504                 goto out_buf;
 505         }
 506         if (atomic_read(&dev_info->use_count) != 0) {
 507                 up_write(&dcssblk_devices_sem);
 508                 PRINT_WARN("Segment %s is in use!\n", local_buf);
 509                 rc = -EBUSY;
 510                 goto out_buf;
 511         }
 512         list_del(&dev_info->lh);
 513
 514         del_gendisk(dev_info->gd);
 515         blk_cleanup_queue(dev_info->dcssblk_queue);
 516         dev_info->gd->queue = NULL;
 517         put_disk(dev_info->gd);
 518         device_unregister(&dev_info->dev);
 519         segment_unload(dev_info->segment_name);
 520         PRINT_DEBUG("Segment %s unloaded successfully\n",
 521                         dev_info->segment_name);
 522         put_device(&dev_info->dev);
 523         up_write(&dcssblk_devices_sem);
 524
 525         rc = count;
 526 out_buf:
 527         kfree(local_buf);
 528         return rc;
 529 }
 530
 531 static int
 532 dcssblk_open(struct inode *inode, struct file *filp)
 533 {
 534         struct dcssblk_dev_info *dev_info;
 535         int rc;
 536
 537         dev_info = inode->i_bdev->bd_disk->private_data;
 538         if (NULL == dev_info) {
 539                 rc = -ENODEV;
 540                 goto out;
 541         }
 542         atomic_inc(&dev_info->use_count);
 543         inode->i_bdev->bd_block_size = 4096;
 544         rc = 0;
 545 out:
 546         return rc;
 547 }
 548
 549 static int
 550 dcssblk_release(struct inode *inode, struct file *filp)
 551 {
 552         struct dcssblk_dev_info *dev_info;
 553         int rc;
 554
 555         dev_info = inode->i_bdev->bd_disk->private_data;
 556         if (NULL == dev_info) {
 557                 rc = -ENODEV;
 558                 goto out;
 559         }
 560         down_write(&dcssblk_devices_sem);
 561         if (atomic_dec_and_test(&dev_info->use_count)
 562             && (dev_info->save_pending)) {
 563                 PRINT_INFO("Segment %s became idle and is being saved now\n",
 564                             dev_info->segment_name);
 565                 segment_save(dev_info->segment_name);
 566                 dev_info->save_pending = 0;
 567         }
 568         up_write(&dcssblk_devices_sem);
 569         rc = 0;
 570 out:
 571         return rc;
 572 }
 573
 574 static int
 575 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 576 {
 577         struct dcssblk_dev_info *dev_info;
 578         struct bio_vec *bvec;
 579         unsigned long index;
 580         unsigned long page_addr;
 581         unsigned long source_addr;
 582         unsigned long bytes_done;
 583         int i;
 584
 585         bytes_done = 0;
 586         dev_info = bio->bi_bdev->bd_disk->private_data;
 587         if (dev_info == NULL)
 588                 goto fail;
 589         if ((bio->bi_sector & 7) != 0 || (bio->bi_size & 4095) != 0)
 590                 /* Request is not page-aligned. */
 591                 goto fail;
 592         if (((bio->bi_size >> 9) + bio->bi_sector)
 593                         > get_capacity(bio->bi_bdev->bd_disk)) {
 594                 /* Request beyond end of DCSS segment. */
 595                 goto fail;
 596         }
 597         /* verify data transfer direction */
 598         if (dev_info->is_shared) {
 599                 switch (dev_info->segment_type) {
 600                 case SEG_TYPE_SR:
 601                 case SEG_TYPE_ER:
 602                 case SEG_TYPE_SC:
 603                         /* cannot write to these segments */
 604                         if (bio_data_dir(bio) == WRITE) {
 605                                 PRINT_WARN("rejecting write to ro segment %s\n", dev_info->dev.bus_id);
 606                                 goto fail;
 607                         }
 608                 }
 609         }
 610
 611         index = (bio->bi_sector >> 3);
 612         bio_for_each_segment(bvec, bio, i) {
 613                 page_addr = (unsigned long)
 614                         page_address(bvec->bv_page) + bvec->bv_offset;
 615                 source_addr = dev_info->start + (index<<12) + bytes_done;
 616                 if (unlikely((page_addr & 4095) != 0) || (bvec->bv_len & 4095) != 0)
 617                         // More paranoia.
 618                         goto fail;
 619                 if (bio_data_dir(bio) == READ) {
 620                         memcpy((void*)page_addr, (void*)source_addr,
 621                                 bvec->bv_len);
 622                 } else {
 623                         memcpy((void*)source_addr, (void*)page_addr,
 624                                 bvec->bv_len);
 625                 }
 626                 bytes_done += bvec->bv_len;
 627         }
 628         bio_endio(bio, 0);
 629         return 0;
 630 fail:
 631         bio_io_error(bio);
 632         return 0;
 633 }
 634
 635 static int
 636 dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
 637                         void **kaddr, unsigned long *pfn)
 638 {
 639         struct dcssblk_dev_info *dev_info;
 640         unsigned long pgoff;
 641
 642         dev_info = bdev->bd_disk->private_data;
 643         if (!dev_info)
 644                 return -ENODEV;
 645         if (secnum % (PAGE_SIZE/512))
 646                 return -EINVAL;
 647         pgoff = secnum / (PAGE_SIZE / 512);
 648         if ((pgoff+1)*PAGE_SIZE-1 > dev_info->end - dev_info->start)
 649                 return -ERANGE;
 650         *kaddr = (void *) (dev_info->start+pgoff*PAGE_SIZE);
 651         *pfn = virt_to_phys(*kaddr) >> PAGE_SHIFT;
 652
 653         return 0;
 654 }
 655
 656 static void
 657 dcssblk_check_params(void)
 658 {
 659         int rc, i, j, k;
 660         char buf[9];
 661         struct dcssblk_dev_info *dev_info;
 662
 663         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 664              i++) {
 665                 for (j = i; (dcssblk_segments[j] != ',')  &&
 666                             (dcssblk_segments[j] != '\0') &&
 667                             (dcssblk_segments[j] != '(')  &&
 668                             (j - i) < 8; j++)
 669                 {
 670                         buf[j-i] = dcssblk_segments[j];
 671                 }
 672                 buf[j-i] = '\0';
 673                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 674                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 675                         for (k = 0; buf[k] != '\0'; k++)
 676                                 buf[k] = toupper(buf[k]);
 677                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 678                                 down_read(&dcssblk_devices_sem);
 679                                 dev_info = dcssblk_get_device_by_name(buf);
 680                                 up_read(&dcssblk_devices_sem);
 681                                 if (dev_info)
 682                                         dcssblk_shared_store(&dev_info->dev,
 683                                                              NULL, "0\n", 2);
 684                         }
 685                 }
 686                 while ((dcssblk_segments[j] != ',') &&
 687                        (dcssblk_segments[j] != '\0'))
 688                 {
 689                         j++;
 690                 }
 691                 if (dcssblk_segments[j] == '\0')
 692                         break;
 693                 i = j;
 694         }
 695 }
 696
 697 /*
 698  * The init/exit functions.
 699  */
 700 static void __exit
 701 dcssblk_exit(void)
 702 {
 703         s390_root_dev_unregister(dcssblk_root_dev);
 704         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
 705 }
 706
 707 static int __init
 708 dcssblk_init(void)
 709 {
 710         int rc;
 711
 712         dcssblk_root_dev = s390_root_dev_register("dcssblk");
 713         if (IS_ERR(dcssblk_root_dev))
 714                 return PTR_ERR(dcssblk_root_dev);
 715         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
 716         if (rc) {
 717                 s390_root_dev_unregister(dcssblk_root_dev);
 718                 return rc;
 719         }
 720         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
 721         if (rc) {
 722                 s390_root_dev_unregister(dcssblk_root_dev);
 723                 return rc;
 724         }
 725         rc = register_blkdev(0, DCSSBLK_NAME);
 726         if (rc < 0) {
 727                 s390_root_dev_unregister(dcssblk_root_dev);
 728                 return rc;
 729         }
 730         dcssblk_major = rc;
 731         init_rwsem(&dcssblk_devices_sem);
 732
 733         dcssblk_check_params();
 734
 735         return 0;
 736 }
 737
 738 module_init(dcssblk_init);
 739 module_exit(dcssblk_exit);
 740
 741 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
 742 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
 743                  "comma-separated list, each name max. 8 chars.\n"
 744                  "Adding \"(local)\" to segment name equals echoing 0 to "
 745                  "/sys/devices/dcssblk/<segment name>/shared after loading "
 746                  "the segment - \n"
 747                  "e.g. segments=\"mydcss1,mydcss2,mydcss3(local)\"");
 748
 749 MODULE_LICENSE("GPL");