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 #define KMSG_COMPONENT "dcssblk"
   8 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
   9
  10 #include <linux/module.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/ctype.h>
  13 #include <linux/errno.h>
  14 #include <linux/init.h>
  15 #include <linux/slab.h>
  16 #include <linux/blkdev.h>
  17 #include <linux/completion.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/platform_device.h>
  20 #include <asm/extmem.h>
  21 #include <asm/io.h>
  22
  23 #define DCSSBLK_NAME "dcssblk"
  24 #define DCSSBLK_MINORS_PER_DISK 1
  25 #define DCSSBLK_PARM_LEN 400
  26 #define DCSS_BUS_ID_SIZE 20
  27
  28 static int dcssblk_open(struct block_device *bdev, fmode_t mode);
  29 static void dcssblk_release(struct gendisk *disk, fmode_t mode);
  30 static void dcssblk_make_request(struct request_queue *q, struct bio *bio);
  31 static int dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
  32                                  void **kaddr, unsigned long *pfn);
  33
  34 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
  35
  36 static int dcssblk_major;
  37 static const struct block_device_operations dcssblk_devops = {
  38         .owner          = THIS_MODULE,
  39         .open           = dcssblk_open,
  40         .release        = dcssblk_release,
  41         .direct_access  = dcssblk_direct_access,
  42 };
  43
  44 struct dcssblk_dev_info {
  45         struct list_head lh;
  46         struct device dev;
  47         char segment_name[DCSS_BUS_ID_SIZE];
  48         atomic_t use_count;
  49         struct gendisk *gd;
  50         unsigned long start;
  51         unsigned long end;
  52         int segment_type;
  53         unsigned char save_pending;
  54         unsigned char is_shared;
  55         struct request_queue *dcssblk_queue;
  56         int num_of_segments;
  57         struct list_head seg_list;
  58 };
  59
  60 struct segment_info {
  61         struct list_head lh;
  62         char segment_name[DCSS_BUS_ID_SIZE];
  63         unsigned long start;
  64         unsigned long end;
  65         int segment_type;
  66 };
  67
  68 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  69                                   size_t count);
  70 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  71                                   size_t count);
  72
  73 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  74 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  75
  76 static struct device *dcssblk_root_dev;
  77
  78 static LIST_HEAD(dcssblk_devices);
  79 static struct rw_semaphore dcssblk_devices_sem;
  80
  81 /*
  82  * release function for segment device.
  83  */
  84 static void
  85 dcssblk_release_segment(struct device *dev)
  86 {
  87         struct dcssblk_dev_info *dev_info;
  88         struct segment_info *entry, *temp;
  89
  90         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
  91         list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
  92                 list_del(&entry->lh);
  93                 kfree(entry);
  94         }
  95         kfree(dev_info);
  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 /*
 146  * get the struct segment_info from seg_list
 147  * for the given name.
 148  * down_read(&dcssblk_devices_sem) must be held.
 149  */
 150 static struct segment_info *
 151 dcssblk_get_segment_by_name(char *name)
 152 {
 153         struct dcssblk_dev_info *dev_info;
 154         struct segment_info *entry;
 155
 156         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 157                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 158                         if (!strcmp(name, entry->segment_name))
 159                                 return entry;
 160                 }
 161         }
 162         return NULL;
 163 }
 164
 165 /*
 166  * get the highest address of the multi-segment block.
 167  */
 168 static unsigned long
 169 dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
 170 {
 171         unsigned long highest_addr;
 172         struct segment_info *entry;
 173
 174         highest_addr = 0;
 175         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 176                 if (highest_addr < entry->end)
 177                         highest_addr = entry->end;
 178         }
 179         return highest_addr;
 180 }
 181
 182 /*
 183  * get the lowest address of the multi-segment block.
 184  */
 185 static unsigned long
 186 dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
 187 {
 188         int set_first;
 189         unsigned long lowest_addr;
 190         struct segment_info *entry;
 191
 192         set_first = 0;
 193         lowest_addr = 0;
 194         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 195                 if (set_first == 0) {
 196                         lowest_addr = entry->start;
 197                         set_first = 1;
 198                 } else {
 199                         if (lowest_addr > entry->start)
 200                                 lowest_addr = entry->start;
 201                 }
 202         }
 203         return lowest_addr;
 204 }
 205
 206 /*
 207  * Check continuity of segments.
 208  */
 209 static int
 210 dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
 211 {
 212         int i, j, rc;
 213         struct segment_info *sort_list, *entry, temp;
 214
 215         if (dev_info->num_of_segments <= 1)
 216                 return 0;
 217
 218         sort_list = kzalloc(
 219                         sizeof(struct segment_info) * dev_info->num_of_segments,
 220                         GFP_KERNEL);
 221         if (sort_list == NULL)
 222                 return -ENOMEM;
 223         i = 0;
 224         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 225                 memcpy(&sort_list[i], entry, sizeof(struct segment_info));
 226                 i++;
 227         }
 228
 229         /* sort segments */
 230         for (i = 0; i < dev_info->num_of_segments; i++)
 231                 for (j = 0; j < dev_info->num_of_segments; j++)
 232                         if (sort_list[j].start > sort_list[i].start) {
 233                                 memcpy(&temp, &sort_list[i],
 234                                         sizeof(struct segment_info));
 235                                 memcpy(&sort_list[i], &sort_list[j],
 236                                         sizeof(struct segment_info));
 237                                 memcpy(&sort_list[j], &temp,
 238                                         sizeof(struct segment_info));
 239                         }
 240
 241         /* check continuity */
 242         for (i = 0; i < dev_info->num_of_segments - 1; i++) {
 243                 if ((sort_list[i].end + 1) != sort_list[i+1].start) {
 244                         pr_err("Adjacent DCSSs %s and %s are not "
 245                                "contiguous\n", sort_list[i].segment_name,
 246                                sort_list[i+1].segment_name);
 247                         rc = -EINVAL;
 248                         goto out;
 249                 }
 250                 /* EN and EW are allowed in a block device */
 251                 if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
 252                         if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
 253                                 (sort_list[i].segment_type == SEG_TYPE_ER) ||
 254                                 !(sort_list[i+1].segment_type &
 255                                 SEGMENT_EXCLUSIVE) ||
 256                                 (sort_list[i+1].segment_type == SEG_TYPE_ER)) {
 257                                 pr_err("DCSS %s and DCSS %s have "
 258                                        "incompatible types\n",
 259                                        sort_list[i].segment_name,
 260                                        sort_list[i+1].segment_name);
 261                                 rc = -EINVAL;
 262                                 goto out;
 263                         }
 264                 }
 265         }
 266         rc = 0;
 267 out:
 268         kfree(sort_list);
 269         return rc;
 270 }
 271
 272 /*
 273  * Load a segment
 274  */
 275 static int
 276 dcssblk_load_segment(char *name, struct segment_info **seg_info)
 277 {
 278         int rc;
 279
 280         /* already loaded? */
 281         down_read(&dcssblk_devices_sem);
 282         *seg_info = dcssblk_get_segment_by_name(name);
 283         up_read(&dcssblk_devices_sem);
 284         if (*seg_info != NULL)
 285                 return -EEXIST;
 286
 287         /* get a struct segment_info */
 288         *seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
 289         if (*seg_info == NULL)
 290                 return -ENOMEM;
 291
 292         strcpy((*seg_info)->segment_name, name);
 293
 294         /* load the segment */
 295         rc = segment_load(name, SEGMENT_SHARED,
 296                         &(*seg_info)->start, &(*seg_info)->end);
 297         if (rc < 0) {
 298                 segment_warning(rc, (*seg_info)->segment_name);
 299                 kfree(*seg_info);
 300         } else {
 301                 INIT_LIST_HEAD(&(*seg_info)->lh);
 302                 (*seg_info)->segment_type = rc;
 303         }
 304         return rc;
 305 }
 306
 307 static void dcssblk_unregister_callback(struct device *dev)
 308 {
 309         device_unregister(dev);
 310         put_device(dev);
 311 }
 312
 313 /*
 314  * device attribute for switching shared/nonshared (exclusive)
 315  * operation (show + store)
 316  */
 317 static ssize_t
 318 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 319 {
 320         struct dcssblk_dev_info *dev_info;
 321
 322         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 323         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 324 }
 325
 326 static ssize_t
 327 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 328 {
 329         struct dcssblk_dev_info *dev_info;
 330         struct segment_info *entry, *temp;
 331         int rc;
 332
 333         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 334                 return -EINVAL;
 335         down_write(&dcssblk_devices_sem);
 336         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 337         if (atomic_read(&dev_info->use_count)) {
 338                 rc = -EBUSY;
 339                 goto out;
 340         }
 341         if (inbuf[0] == '1') {
 342                 /* reload segments in shared mode */
 343                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 344                         rc = segment_modify_shared(entry->segment_name,
 345                                                 SEGMENT_SHARED);
 346                         if (rc < 0) {
 347                                 BUG_ON(rc == -EINVAL);
 348                                 if (rc != -EAGAIN)
 349                                         goto removeseg;
 350                         }
 351                 }
 352                 dev_info->is_shared = 1;
 353                 switch (dev_info->segment_type) {
 354                 case SEG_TYPE_SR:
 355                 case SEG_TYPE_ER:
 356                 case SEG_TYPE_SC:
 357                         set_disk_ro(dev_info->gd, 1);
 358                 }
 359         } else if (inbuf[0] == '0') {
 360                 /* reload segments in exclusive mode */
 361                 if (dev_info->segment_type == SEG_TYPE_SC) {
 362                         pr_err("DCSS %s is of type SC and cannot be "
 363                                "loaded as exclusive-writable\n",
 364                                dev_info->segment_name);
 365                         rc = -EINVAL;
 366                         goto out;
 367                 }
 368                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 369                         rc = segment_modify_shared(entry->segment_name,
 370                                                    SEGMENT_EXCLUSIVE);
 371                         if (rc < 0) {
 372                                 BUG_ON(rc == -EINVAL);
 373                                 if (rc != -EAGAIN)
 374                                         goto removeseg;
 375                         }
 376                 }
 377                 dev_info->is_shared = 0;
 378                 set_disk_ro(dev_info->gd, 0);
 379         } else {
 380                 rc = -EINVAL;
 381                 goto out;
 382         }
 383         rc = count;
 384         goto out;
 385
 386 removeseg:
 387         pr_err("DCSS device %s is removed after a failed access mode "
 388                "change\n", dev_info->segment_name);
 389         temp = entry;
 390         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 391                 if (entry != temp)
 392                         segment_unload(entry->segment_name);
 393         }
 394         list_del(&dev_info->lh);
 395
 396         del_gendisk(dev_info->gd);
 397         blk_cleanup_queue(dev_info->dcssblk_queue);
 398         dev_info->gd->queue = NULL;
 399         put_disk(dev_info->gd);
 400         rc = device_schedule_callback(dev, dcssblk_unregister_callback);
 401 out:
 402         up_write(&dcssblk_devices_sem);
 403         return rc;
 404 }
 405 static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
 406                    dcssblk_shared_store);
 407
 408 /*
 409  * device attribute for save operation on current copy
 410  * of the segment. If the segment is busy, saving will
 411  * become pending until it gets released, which can be
 412  * undone by storing a non-true value to this entry.
 413  * (show + store)
 414  */
 415 static ssize_t
 416 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 417 {
 418         struct dcssblk_dev_info *dev_info;
 419
 420         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 421         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 422 }
 423
 424 static ssize_t
 425 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 426 {
 427         struct dcssblk_dev_info *dev_info;
 428         struct segment_info *entry;
 429
 430         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 431                 return -EINVAL;
 432         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 433
 434         down_write(&dcssblk_devices_sem);
 435         if (inbuf[0] == '1') {
 436                 if (atomic_read(&dev_info->use_count) == 0) {
 437                         // device is idle => we save immediately
 438                         pr_info("All DCSSs that map to device %s are "
 439                                 "saved\n", dev_info->segment_name);
 440                         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 441                                 segment_save(entry->segment_name);
 442                         }
 443                 }  else {
 444                         // device is busy => we save it when it becomes
 445                         // idle in dcssblk_release
 446                         pr_info("Device %s is in use, its DCSSs will be "
 447                                 "saved when it becomes idle\n",
 448                                 dev_info->segment_name);
 449                         dev_info->save_pending = 1;
 450                 }
 451         } else if (inbuf[0] == '0') {
 452                 if (dev_info->save_pending) {
 453                         // device is busy & the user wants to undo his save
 454                         // request
 455                         dev_info->save_pending = 0;
 456                         pr_info("A pending save request for device %s "
 457                                 "has been canceled\n",
 458                                 dev_info->segment_name);
 459                 }
 460         } else {
 461                 up_write(&dcssblk_devices_sem);
 462                 return -EINVAL;
 463         }
 464         up_write(&dcssblk_devices_sem);
 465         return count;
 466 }
 467 static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
 468                    dcssblk_save_store);
 469
 470 /*
 471  * device attribute for showing all segments in a device
 472  */
 473 static ssize_t
 474 dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
 475                 char *buf)
 476 {
 477         int i;
 478
 479         struct dcssblk_dev_info *dev_info;
 480         struct segment_info *entry;
 481
 482         down_read(&dcssblk_devices_sem);
 483         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 484         i = 0;
 485         buf[0] = '\0';
 486         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 487                 strcpy(&buf[i], entry->segment_name);
 488                 i += strlen(entry->segment_name);
 489                 buf[i] = '\n';
 490                 i++;
 491         }
 492         up_read(&dcssblk_devices_sem);
 493         return i;
 494 }
 495 static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
 496
 497 static struct attribute *dcssblk_dev_attrs[] = {
 498         &dev_attr_shared.attr,
 499         &dev_attr_save.attr,
 500         &dev_attr_seglist.attr,
 501         NULL,
 502 };
 503 static struct attribute_group dcssblk_dev_attr_group = {
 504         .attrs = dcssblk_dev_attrs,
 505 };
 506 static const struct attribute_group *dcssblk_dev_attr_groups[] = {
 507         &dcssblk_dev_attr_group,
 508         NULL,
 509 };
 510
 511 /*
 512  * device attribute for adding devices
 513  */
 514 static ssize_t
 515 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 516 {
 517         int rc, i, j, num_of_segments;
 518         struct dcssblk_dev_info *dev_info;
 519         struct segment_info *seg_info, *temp;
 520         char *local_buf;
 521         unsigned long seg_byte_size;
 522
 523         dev_info = NULL;
 524         seg_info = NULL;
 525         if (dev != dcssblk_root_dev) {
 526                 rc = -EINVAL;
 527                 goto out_nobuf;
 528         }
 529         if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 530                 rc = -ENAMETOOLONG;
 531                 goto out_nobuf;
 532         }
 533
 534         local_buf = kmalloc(count + 1, GFP_KERNEL);
 535         if (local_buf == NULL) {
 536                 rc = -ENOMEM;
 537                 goto out_nobuf;
 538         }
 539
 540         /*
 541          * parse input
 542          */
 543         num_of_segments = 0;
 544         for (i = 0; ((buf[i] != '\0') && (buf[i] != '\n') && i < count); i++) {
 545                 for (j = i; (buf[j] != ':') &&
 546                         (buf[j] != '\0') &&
 547                         (buf[j] != '\n') &&
 548                         j < count; j++) {
 549                         local_buf[j-i] = toupper(buf[j]);
 550                 }
 551                 local_buf[j-i] = '\0';
 552                 if (((j - i) == 0) || ((j - i) > 8)) {
 553                         rc = -ENAMETOOLONG;
 554                         goto seg_list_del;
 555                 }
 556
 557                 rc = dcssblk_load_segment(local_buf, &seg_info);
 558                 if (rc < 0)
 559                         goto seg_list_del;
 560                 /*
 561                  * get a struct dcssblk_dev_info
 562                  */
 563                 if (num_of_segments == 0) {
 564                         dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 565                                         GFP_KERNEL);
 566                         if (dev_info == NULL) {
 567                                 rc = -ENOMEM;
 568                                 goto out;
 569                         }
 570                         strcpy(dev_info->segment_name, local_buf);
 571                         dev_info->segment_type = seg_info->segment_type;
 572                         INIT_LIST_HEAD(&dev_info->seg_list);
 573                 }
 574                 list_add_tail(&seg_info->lh, &dev_info->seg_list);
 575                 num_of_segments++;
 576                 i = j;
 577
 578                 if ((buf[j] == '\0') || (buf[j] == '\n'))
 579                         break;
 580         }
 581
 582         /* no trailing colon at the end of the input */
 583         if ((i > 0) && (buf[i-1] == ':')) {
 584                 rc = -ENAMETOOLONG;
 585                 goto seg_list_del;
 586         }
 587         strlcpy(local_buf, buf, i + 1);
 588         dev_info->num_of_segments = num_of_segments;
 589         rc = dcssblk_is_continuous(dev_info);
 590         if (rc < 0)
 591                 goto seg_list_del;
 592
 593         dev_info->start = dcssblk_find_lowest_addr(dev_info);
 594         dev_info->end = dcssblk_find_highest_addr(dev_info);
 595
 596         dev_set_name(&dev_info->dev, dev_info->segment_name);
 597         dev_info->dev.release = dcssblk_release_segment;
 598         dev_info->dev.groups = dcssblk_dev_attr_groups;
 599         INIT_LIST_HEAD(&dev_info->lh);
 600         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 601         if (dev_info->gd == NULL) {
 602                 rc = -ENOMEM;
 603                 goto seg_list_del;
 604         }
 605         dev_info->gd->major = dcssblk_major;
 606         dev_info->gd->fops = &dcssblk_devops;
 607         dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 608         dev_info->gd->queue = dev_info->dcssblk_queue;
 609         dev_info->gd->private_data = dev_info;
 610         dev_info->gd->driverfs_dev = &dev_info->dev;
 611         blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 612         blk_queue_logical_block_size(dev_info->dcssblk_queue, 4096);
 613
 614         seg_byte_size = (dev_info->end - dev_info->start + 1);
 615         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 616         pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 617                 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 618
 619         dev_info->save_pending = 0;
 620         dev_info->is_shared = 1;
 621         dev_info->dev.parent = dcssblk_root_dev;
 622
 623         /*
 624          *get minor, add to list
 625          */
 626         down_write(&dcssblk_devices_sem);
 627         if (dcssblk_get_segment_by_name(local_buf)) {
 628                 rc = -EEXIST;
 629                 goto release_gd;
 630         }
 631         rc = dcssblk_assign_free_minor(dev_info);
 632         if (rc)
 633                 goto release_gd;
 634         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 635                 dev_info->gd->first_minor);
 636         list_add_tail(&dev_info->lh, &dcssblk_devices);
 637
 638         if (!try_module_get(THIS_MODULE)) {
 639                 rc = -ENODEV;
 640                 goto dev_list_del;
 641         }
 642         /*
 643          * register the device
 644          */
 645         rc = device_register(&dev_info->dev);
 646         if (rc)
 647                 goto put_dev;
 648
 649         get_device(&dev_info->dev);
 650         add_disk(dev_info->gd);
 651
 652         switch (dev_info->segment_type) {
 653                 case SEG_TYPE_SR:
 654                 case SEG_TYPE_ER:
 655                 case SEG_TYPE_SC:
 656                         set_disk_ro(dev_info->gd,1);
 657                         break;
 658                 default:
 659                         set_disk_ro(dev_info->gd,0);
 660                         break;
 661         }
 662         up_write(&dcssblk_devices_sem);
 663         rc = count;
 664         goto out;
 665
 666 put_dev:
 667         list_del(&dev_info->lh);
 668         blk_cleanup_queue(dev_info->dcssblk_queue);
 669         dev_info->gd->queue = NULL;
 670         put_disk(dev_info->gd);
 671         list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 672                 segment_unload(seg_info->segment_name);
 673         }
 674         put_device(&dev_info->dev);
 675         up_write(&dcssblk_devices_sem);
 676         goto out;
 677 dev_list_del:
 678         list_del(&dev_info->lh);
 679 release_gd:
 680         blk_cleanup_queue(dev_info->dcssblk_queue);
 681         dev_info->gd->queue = NULL;
 682         put_disk(dev_info->gd);
 683         up_write(&dcssblk_devices_sem);
 684 seg_list_del:
 685         if (dev_info == NULL)
 686                 goto out;
 687         list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 688                 list_del(&seg_info->lh);
 689                 segment_unload(seg_info->segment_name);
 690                 kfree(seg_info);
 691         }
 692         kfree(dev_info);
 693 out:
 694         kfree(local_buf);
 695 out_nobuf:
 696         return rc;
 697 }
 698
 699 /*
 700  * device attribute for removing devices
 701  */
 702 static ssize_t
 703 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 704 {
 705         struct dcssblk_dev_info *dev_info;
 706         struct segment_info *entry;
 707         int rc, i;
 708         char *local_buf;
 709
 710         if (dev != dcssblk_root_dev) {
 711                 return -EINVAL;
 712         }
 713         local_buf = kmalloc(count + 1, GFP_KERNEL);
 714         if (local_buf == NULL) {
 715                 return -ENOMEM;
 716         }
 717         /*
 718          * parse input
 719          */
 720         for (i = 0; ((*(buf+i)!='\0') && (*(buf+i)!='\n') && i < count); i++) {
 721                 local_buf[i] = toupper(buf[i]);
 722         }
 723         local_buf[i] = '\0';
 724         if ((i == 0) || (i > 8)) {
 725                 rc = -ENAMETOOLONG;
 726                 goto out_buf;
 727         }
 728
 729         down_write(&dcssblk_devices_sem);
 730         dev_info = dcssblk_get_device_by_name(local_buf);
 731         if (dev_info == NULL) {
 732                 up_write(&dcssblk_devices_sem);
 733                 pr_warning("Device %s cannot be removed because it is not a "
 734                            "known device\n", local_buf);
 735                 rc = -ENODEV;
 736                 goto out_buf;
 737         }
 738         if (atomic_read(&dev_info->use_count) != 0) {
 739                 up_write(&dcssblk_devices_sem);
 740                 pr_warning("Device %s cannot be removed while it is in "
 741                            "use\n", local_buf);
 742                 rc = -EBUSY;
 743                 goto out_buf;
 744         }
 745
 746         list_del(&dev_info->lh);
 747         del_gendisk(dev_info->gd);
 748         blk_cleanup_queue(dev_info->dcssblk_queue);
 749         dev_info->gd->queue = NULL;
 750         put_disk(dev_info->gd);
 751         device_unregister(&dev_info->dev);
 752
 753         /* unload all related segments */
 754         list_for_each_entry(entry, &dev_info->seg_list, lh)
 755                 segment_unload(entry->segment_name);
 756
 757         put_device(&dev_info->dev);
 758         up_write(&dcssblk_devices_sem);
 759
 760         rc = count;
 761 out_buf:
 762         kfree(local_buf);
 763         return rc;
 764 }
 765
 766 static int
 767 dcssblk_open(struct block_device *bdev, fmode_t mode)
 768 {
 769         struct dcssblk_dev_info *dev_info;
 770         int rc;
 771
 772         dev_info = bdev->bd_disk->private_data;
 773         if (NULL == dev_info) {
 774                 rc = -ENODEV;
 775                 goto out;
 776         }
 777         atomic_inc(&dev_info->use_count);
 778         bdev->bd_block_size = 4096;
 779         rc = 0;
 780 out:
 781         return rc;
 782 }
 783
 784 static void
 785 dcssblk_release(struct gendisk *disk, fmode_t mode)
 786 {
 787         struct dcssblk_dev_info *dev_info = disk->private_data;
 788         struct segment_info *entry;
 789
 790         if (!dev_info) {
 791                 WARN_ON(1);
 792                 return;
 793         }
 794         down_write(&dcssblk_devices_sem);
 795         if (atomic_dec_and_test(&dev_info->use_count)
 796             && (dev_info->save_pending)) {
 797                 pr_info("Device %s has become idle and is being saved "
 798                         "now\n", dev_info->segment_name);
 799                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 800                         segment_save(entry->segment_name);
 801                 }
 802                 dev_info->save_pending = 0;
 803         }
 804         up_write(&dcssblk_devices_sem);
 805 }
 806
 807 static void
 808 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 809 {
 810         struct dcssblk_dev_info *dev_info;
 811         struct bio_vec bvec;
 812         struct bvec_iter iter;
 813         unsigned long index;
 814         unsigned long page_addr;
 815         unsigned long source_addr;
 816         unsigned long bytes_done;
 817
 818         bytes_done = 0;
 819         dev_info = bio->bi_bdev->bd_disk->private_data;
 820         if (dev_info == NULL)
 821                 goto fail;
 822         if ((bio->bi_iter.bi_sector & 7) != 0 ||
 823             (bio->bi_iter.bi_size & 4095) != 0)
 824                 /* Request is not page-aligned. */
 825                 goto fail;
 826         if (bio_end_sector(bio) > get_capacity(bio->bi_bdev->bd_disk)) {
 827                 /* Request beyond end of DCSS segment. */
 828                 goto fail;
 829         }
 830         /* verify data transfer direction */
 831         if (dev_info->is_shared) {
 832                 switch (dev_info->segment_type) {
 833                 case SEG_TYPE_SR:
 834                 case SEG_TYPE_ER:
 835                 case SEG_TYPE_SC:
 836                         /* cannot write to these segments */
 837                         if (bio_data_dir(bio) == WRITE) {
 838                                 pr_warning("Writing to %s failed because it "
 839                                            "is a read-only device\n",
 840                                            dev_name(&dev_info->dev));
 841                                 goto fail;
 842                         }
 843                 }
 844         }
 845
 846         index = (bio->bi_iter.bi_sector >> 3);
 847         bio_for_each_segment(bvec, bio, iter) {
 848                 page_addr = (unsigned long)
 849                         page_address(bvec.bv_page) + bvec.bv_offset;
 850                 source_addr = dev_info->start + (index<<12) + bytes_done;
 851                 if (unlikely((page_addr & 4095) != 0) || (bvec.bv_len & 4095) != 0)
 852                         // More paranoia.
 853                         goto fail;
 854                 if (bio_data_dir(bio) == READ) {
 855                         memcpy((void*)page_addr, (void*)source_addr,
 856                                 bvec.bv_len);
 857                 } else {
 858                         memcpy((void*)source_addr, (void*)page_addr,
 859                                 bvec.bv_len);
 860                 }
 861                 bytes_done += bvec.bv_len;
 862         }
 863         bio_endio(bio, 0);
 864         return;
 865 fail:
 866         bio_io_error(bio);
 867 }
 868
 869 static int
 870 dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
 871                         void **kaddr, unsigned long *pfn)
 872 {
 873         struct dcssblk_dev_info *dev_info;
 874         unsigned long pgoff;
 875
 876         dev_info = bdev->bd_disk->private_data;
 877         if (!dev_info)
 878                 return -ENODEV;
 879         if (secnum % (PAGE_SIZE/512))
 880                 return -EINVAL;
 881         pgoff = secnum / (PAGE_SIZE / 512);
 882         if ((pgoff+1)*PAGE_SIZE-1 > dev_info->end - dev_info->start)
 883                 return -ERANGE;
 884         *kaddr = (void *) (dev_info->start+pgoff*PAGE_SIZE);
 885         *pfn = virt_to_phys(*kaddr) >> PAGE_SHIFT;
 886
 887         return 0;
 888 }
 889
 890 static void
 891 dcssblk_check_params(void)
 892 {
 893         int rc, i, j, k;
 894         char buf[DCSSBLK_PARM_LEN + 1];
 895         struct dcssblk_dev_info *dev_info;
 896
 897         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 898              i++) {
 899                 for (j = i; (dcssblk_segments[j] != ',')  &&
 900                             (dcssblk_segments[j] != '\0') &&
 901                             (dcssblk_segments[j] != '(')  &&
 902                             (j < DCSSBLK_PARM_LEN); j++)
 903                 {
 904                         buf[j-i] = dcssblk_segments[j];
 905                 }
 906                 buf[j-i] = '\0';
 907                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 908                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 909                         for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 910                                 buf[k] = toupper(buf[k]);
 911                         buf[k] = '\0';
 912                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 913                                 down_read(&dcssblk_devices_sem);
 914                                 dev_info = dcssblk_get_device_by_name(buf);
 915                                 up_read(&dcssblk_devices_sem);
 916                                 if (dev_info)
 917                                         dcssblk_shared_store(&dev_info->dev,
 918                                                              NULL, "0\n", 2);
 919                         }
 920                 }
 921                 while ((dcssblk_segments[j] != ',') &&
 922                        (dcssblk_segments[j] != '\0'))
 923                 {
 924                         j++;
 925                 }
 926                 if (dcssblk_segments[j] == '\0')
 927                         break;
 928                 i = j;
 929         }
 930 }
 931
 932 /*
 933  * Suspend / Resume
 934  */
 935 static int dcssblk_freeze(struct device *dev)
 936 {
 937         struct dcssblk_dev_info *dev_info;
 938         int rc = 0;
 939
 940         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 941                 switch (dev_info->segment_type) {
 942                         case SEG_TYPE_SR:
 943                         case SEG_TYPE_ER:
 944                         case SEG_TYPE_SC:
 945                                 if (!dev_info->is_shared)
 946                                         rc = -EINVAL;
 947                                 break;
 948                         default:
 949                                 rc = -EINVAL;
 950                                 break;
 951                 }
 952                 if (rc)
 953                         break;
 954         }
 955         if (rc)
 956                 pr_err("Suspending the system failed because DCSS device %s "
 957                        "is writable\n",
 958                        dev_info->segment_name);
 959         return rc;
 960 }
 961
 962 static int dcssblk_restore(struct device *dev)
 963 {
 964         struct dcssblk_dev_info *dev_info;
 965         struct segment_info *entry;
 966         unsigned long start, end;
 967         int rc = 0;
 968
 969         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 970                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 971                         segment_unload(entry->segment_name);
 972                         rc = segment_load(entry->segment_name, SEGMENT_SHARED,
 973                                           &start, &end);
 974                         if (rc < 0) {
 975 // TODO in_use check ?
 976                                 segment_warning(rc, entry->segment_name);
 977                                 goto out_panic;
 978                         }
 979                         if (start != entry->start || end != entry->end) {
 980                                 pr_err("The address range of DCSS %s changed "
 981                                        "while the system was suspended\n",
 982                                        entry->segment_name);
 983                                 goto out_panic;
 984                         }
 985                 }
 986         }
 987         return 0;
 988 out_panic:
 989         panic("fatal dcssblk resume error\n");
 990 }
 991
 992 static int dcssblk_thaw(struct device *dev)
 993 {
 994         return 0;
 995 }
 996
 997 static const struct dev_pm_ops dcssblk_pm_ops = {
 998         .freeze         = dcssblk_freeze,
 999         .thaw           = dcssblk_thaw,
1000         .restore        = dcssblk_restore,
1001 };
1002
1003 static struct platform_driver dcssblk_pdrv = {
1004         .driver = {
1005                 .name   = "dcssblk",
1006                 .owner  = THIS_MODULE,
1007                 .pm     = &dcssblk_pm_ops,
1008         },
1009 };
1010
1011 static struct platform_device *dcssblk_pdev;
1012
1013
1014 /*
1015  * The init/exit functions.
1016  */
1017 static void __exit
1018 dcssblk_exit(void)
1019 {
1020         platform_device_unregister(dcssblk_pdev);
1021         platform_driver_unregister(&dcssblk_pdrv);
1022         root_device_unregister(dcssblk_root_dev);
1023         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
1024 }
1025
1026 static int __init
1027 dcssblk_init(void)
1028 {
1029         int rc;
1030
1031         rc = platform_driver_register(&dcssblk_pdrv);
1032         if (rc)
1033                 return rc;
1034
1035         dcssblk_pdev = platform_device_register_simple("dcssblk", -1, NULL,
1036                                                         0);
1037         if (IS_ERR(dcssblk_pdev)) {
1038                 rc = PTR_ERR(dcssblk_pdev);
1039                 goto out_pdrv;
1040         }
1041
1042         dcssblk_root_dev = root_device_register("dcssblk");
1043         if (IS_ERR(dcssblk_root_dev)) {
1044                 rc = PTR_ERR(dcssblk_root_dev);
1045                 goto out_pdev;
1046         }
1047         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1048         if (rc)
1049                 goto out_root;
1050         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1051         if (rc)
1052                 goto out_root;
1053         rc = register_blkdev(0, DCSSBLK_NAME);
1054         if (rc < 0)
1055                 goto out_root;
1056         dcssblk_major = rc;
1057         init_rwsem(&dcssblk_devices_sem);
1058
1059         dcssblk_check_params();
1060         return 0;
1061
1062 out_root:
1063         root_device_unregister(dcssblk_root_dev);
1064 out_pdev:
1065         platform_device_unregister(dcssblk_pdev);
1066 out_pdrv:
1067         platform_driver_unregister(&dcssblk_pdrv);
1068         return rc;
1069 }
1070
1071 module_init(dcssblk_init);
1072 module_exit(dcssblk_exit);
1073
1074 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1075 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1076                  "comma-separated list, names in each set separated "
1077                  "by commas are separated by colons, each set contains "
1078                  "names of contiguous segments and each name max. 8 chars.\n"
1079                  "Adding \"(local)\" to the end of each set equals echoing 0 "
1080                  "to /sys/devices/dcssblk/<device name>/shared after loading "
1081                  "the contiguous segments - \n"
1082                  "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1083
1084 MODULE_LICENSE("GPL");