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 blk_qc_t dcssblk_make_request(struct request_queue *q,
  31                                                 struct bio *bio);
  32 static long dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
  33                          void __pmem **kaddr, unsigned long *pfn);
  34
  35 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
  36
  37 static int dcssblk_major;
  38 static const struct block_device_operations dcssblk_devops = {
  39         .owner          = THIS_MODULE,
  40         .open           = dcssblk_open,
  41         .release        = dcssblk_release,
  42         .direct_access  = dcssblk_direct_access,
  43 };
  44
  45 struct dcssblk_dev_info {
  46         struct list_head lh;
  47         struct device dev;
  48         char segment_name[DCSS_BUS_ID_SIZE];
  49         atomic_t use_count;
  50         struct gendisk *gd;
  51         unsigned long start;
  52         unsigned long end;
  53         int segment_type;
  54         unsigned char save_pending;
  55         unsigned char is_shared;
  56         struct request_queue *dcssblk_queue;
  57         int num_of_segments;
  58         struct list_head seg_list;
  59 };
  60
  61 struct segment_info {
  62         struct list_head lh;
  63         char segment_name[DCSS_BUS_ID_SIZE];
  64         unsigned long start;
  65         unsigned long end;
  66         int segment_type;
  67 };
  68
  69 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
  70                                   size_t count);
  71 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
  72                                   size_t count);
  73
  74 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
  75 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
  76
  77 static struct device *dcssblk_root_dev;
  78
  79 static LIST_HEAD(dcssblk_devices);
  80 static struct rw_semaphore dcssblk_devices_sem;
  81
  82 /*
  83  * release function for segment device.
  84  */
  85 static void
  86 dcssblk_release_segment(struct device *dev)
  87 {
  88         struct dcssblk_dev_info *dev_info;
  89         struct segment_info *entry, *temp;
  90
  91         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
  92         list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
  93                 list_del(&entry->lh);
  94                 kfree(entry);
  95         }
  96         kfree(dev_info);
  97         module_put(THIS_MODULE);
  98 }
  99
 100 /*
 101  * get a minor number. needs to be called with
 102  * down_write(&dcssblk_devices_sem) and the
 103  * device needs to be enqueued before the semaphore is
 104  * freed.
 105  */
 106 static int
 107 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
 108 {
 109         int minor, found;
 110         struct dcssblk_dev_info *entry;
 111
 112         if (dev_info == NULL)
 113                 return -EINVAL;
 114         for (minor = 0; minor < (1<<MINORBITS); minor++) {
 115                 found = 0;
 116                 // test if minor available
 117                 list_for_each_entry(entry, &dcssblk_devices, lh)
 118                         if (minor == entry->gd->first_minor)
 119                                 found++;
 120                 if (!found) break; // got unused minor
 121         }
 122         if (found)
 123                 return -EBUSY;
 124         dev_info->gd->first_minor = minor;
 125         return 0;
 126 }
 127
 128 /*
 129  * get the struct dcssblk_dev_info from dcssblk_devices
 130  * for the given name.
 131  * down_read(&dcssblk_devices_sem) must be held.
 132  */
 133 static struct dcssblk_dev_info *
 134 dcssblk_get_device_by_name(char *name)
 135 {
 136         struct dcssblk_dev_info *entry;
 137
 138         list_for_each_entry(entry, &dcssblk_devices, lh) {
 139                 if (!strcmp(name, entry->segment_name)) {
 140                         return entry;
 141                 }
 142         }
 143         return NULL;
 144 }
 145
 146 /*
 147  * get the struct segment_info from seg_list
 148  * for the given name.
 149  * down_read(&dcssblk_devices_sem) must be held.
 150  */
 151 static struct segment_info *
 152 dcssblk_get_segment_by_name(char *name)
 153 {
 154         struct dcssblk_dev_info *dev_info;
 155         struct segment_info *entry;
 156
 157         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 158                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 159                         if (!strcmp(name, entry->segment_name))
 160                                 return entry;
 161                 }
 162         }
 163         return NULL;
 164 }
 165
 166 /*
 167  * get the highest address of the multi-segment block.
 168  */
 169 static unsigned long
 170 dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
 171 {
 172         unsigned long highest_addr;
 173         struct segment_info *entry;
 174
 175         highest_addr = 0;
 176         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 177                 if (highest_addr < entry->end)
 178                         highest_addr = entry->end;
 179         }
 180         return highest_addr;
 181 }
 182
 183 /*
 184  * get the lowest address of the multi-segment block.
 185  */
 186 static unsigned long
 187 dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
 188 {
 189         int set_first;
 190         unsigned long lowest_addr;
 191         struct segment_info *entry;
 192
 193         set_first = 0;
 194         lowest_addr = 0;
 195         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 196                 if (set_first == 0) {
 197                         lowest_addr = entry->start;
 198                         set_first = 1;
 199                 } else {
 200                         if (lowest_addr > entry->start)
 201                                 lowest_addr = entry->start;
 202                 }
 203         }
 204         return lowest_addr;
 205 }
 206
 207 /*
 208  * Check continuity of segments.
 209  */
 210 static int
 211 dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
 212 {
 213         int i, j, rc;
 214         struct segment_info *sort_list, *entry, temp;
 215
 216         if (dev_info->num_of_segments <= 1)
 217                 return 0;
 218
 219         sort_list = kzalloc(
 220                         sizeof(struct segment_info) * dev_info->num_of_segments,
 221                         GFP_KERNEL);
 222         if (sort_list == NULL)
 223                 return -ENOMEM;
 224         i = 0;
 225         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 226                 memcpy(&sort_list[i], entry, sizeof(struct segment_info));
 227                 i++;
 228         }
 229
 230         /* sort segments */
 231         for (i = 0; i < dev_info->num_of_segments; i++)
 232                 for (j = 0; j < dev_info->num_of_segments; j++)
 233                         if (sort_list[j].start > sort_list[i].start) {
 234                                 memcpy(&temp, &sort_list[i],
 235                                         sizeof(struct segment_info));
 236                                 memcpy(&sort_list[i], &sort_list[j],
 237                                         sizeof(struct segment_info));
 238                                 memcpy(&sort_list[j], &temp,
 239                                         sizeof(struct segment_info));
 240                         }
 241
 242         /* check continuity */
 243         for (i = 0; i < dev_info->num_of_segments - 1; i++) {
 244                 if ((sort_list[i].end + 1) != sort_list[i+1].start) {
 245                         pr_err("Adjacent DCSSs %s and %s are not "
 246                                "contiguous\n", sort_list[i].segment_name,
 247                                sort_list[i+1].segment_name);
 248                         rc = -EINVAL;
 249                         goto out;
 250                 }
 251                 /* EN and EW are allowed in a block device */
 252                 if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
 253                         if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
 254                                 (sort_list[i].segment_type == SEG_TYPE_ER) ||
 255                                 !(sort_list[i+1].segment_type &
 256                                 SEGMENT_EXCLUSIVE) ||
 257                                 (sort_list[i+1].segment_type == SEG_TYPE_ER)) {
 258                                 pr_err("DCSS %s and DCSS %s have "
 259                                        "incompatible types\n",
 260                                        sort_list[i].segment_name,
 261                                        sort_list[i+1].segment_name);
 262                                 rc = -EINVAL;
 263                                 goto out;
 264                         }
 265                 }
 266         }
 267         rc = 0;
 268 out:
 269         kfree(sort_list);
 270         return rc;
 271 }
 272
 273 /*
 274  * Load a segment
 275  */
 276 static int
 277 dcssblk_load_segment(char *name, struct segment_info **seg_info)
 278 {
 279         int rc;
 280
 281         /* already loaded? */
 282         down_read(&dcssblk_devices_sem);
 283         *seg_info = dcssblk_get_segment_by_name(name);
 284         up_read(&dcssblk_devices_sem);
 285         if (*seg_info != NULL)
 286                 return -EEXIST;
 287
 288         /* get a struct segment_info */
 289         *seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
 290         if (*seg_info == NULL)
 291                 return -ENOMEM;
 292
 293         strcpy((*seg_info)->segment_name, name);
 294
 295         /* load the segment */
 296         rc = segment_load(name, SEGMENT_SHARED,
 297                         &(*seg_info)->start, &(*seg_info)->end);
 298         if (rc < 0) {
 299                 segment_warning(rc, (*seg_info)->segment_name);
 300                 kfree(*seg_info);
 301         } else {
 302                 INIT_LIST_HEAD(&(*seg_info)->lh);
 303                 (*seg_info)->segment_type = rc;
 304         }
 305         return rc;
 306 }
 307
 308 /*
 309  * device attribute for switching shared/nonshared (exclusive)
 310  * operation (show + store)
 311  */
 312 static ssize_t
 313 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
 314 {
 315         struct dcssblk_dev_info *dev_info;
 316
 317         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 318         return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
 319 }
 320
 321 static ssize_t
 322 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 323 {
 324         struct dcssblk_dev_info *dev_info;
 325         struct segment_info *entry, *temp;
 326         int rc;
 327
 328         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 329                 return -EINVAL;
 330         down_write(&dcssblk_devices_sem);
 331         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 332         if (atomic_read(&dev_info->use_count)) {
 333                 rc = -EBUSY;
 334                 goto out;
 335         }
 336         if (inbuf[0] == '1') {
 337                 /* reload segments in shared mode */
 338                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 339                         rc = segment_modify_shared(entry->segment_name,
 340                                                 SEGMENT_SHARED);
 341                         if (rc < 0) {
 342                                 BUG_ON(rc == -EINVAL);
 343                                 if (rc != -EAGAIN)
 344                                         goto removeseg;
 345                         }
 346                 }
 347                 dev_info->is_shared = 1;
 348                 switch (dev_info->segment_type) {
 349                 case SEG_TYPE_SR:
 350                 case SEG_TYPE_ER:
 351                 case SEG_TYPE_SC:
 352                         set_disk_ro(dev_info->gd, 1);
 353                 }
 354         } else if (inbuf[0] == '0') {
 355                 /* reload segments in exclusive mode */
 356                 if (dev_info->segment_type == SEG_TYPE_SC) {
 357                         pr_err("DCSS %s is of type SC and cannot be "
 358                                "loaded as exclusive-writable\n",
 359                                dev_info->segment_name);
 360                         rc = -EINVAL;
 361                         goto out;
 362                 }
 363                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 364                         rc = segment_modify_shared(entry->segment_name,
 365                                                    SEGMENT_EXCLUSIVE);
 366                         if (rc < 0) {
 367                                 BUG_ON(rc == -EINVAL);
 368                                 if (rc != -EAGAIN)
 369                                         goto removeseg;
 370                         }
 371                 }
 372                 dev_info->is_shared = 0;
 373                 set_disk_ro(dev_info->gd, 0);
 374         } else {
 375                 rc = -EINVAL;
 376                 goto out;
 377         }
 378         rc = count;
 379         goto out;
 380
 381 removeseg:
 382         pr_err("DCSS device %s is removed after a failed access mode "
 383                "change\n", dev_info->segment_name);
 384         temp = entry;
 385         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 386                 if (entry != temp)
 387                         segment_unload(entry->segment_name);
 388         }
 389         list_del(&dev_info->lh);
 390
 391         del_gendisk(dev_info->gd);
 392         blk_cleanup_queue(dev_info->dcssblk_queue);
 393         dev_info->gd->queue = NULL;
 394         put_disk(dev_info->gd);
 395         up_write(&dcssblk_devices_sem);
 396
 397         if (device_remove_file_self(dev, attr)) {
 398                 device_unregister(dev);
 399                 put_device(dev);
 400         }
 401         return rc;
 402 out:
 403         up_write(&dcssblk_devices_sem);
 404         return rc;
 405 }
 406 static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
 407                    dcssblk_shared_store);
 408
 409 /*
 410  * device attribute for save operation on current copy
 411  * of the segment. If the segment is busy, saving will
 412  * become pending until it gets released, which can be
 413  * undone by storing a non-true value to this entry.
 414  * (show + store)
 415  */
 416 static ssize_t
 417 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
 418 {
 419         struct dcssblk_dev_info *dev_info;
 420
 421         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 422         return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
 423 }
 424
 425 static ssize_t
 426 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
 427 {
 428         struct dcssblk_dev_info *dev_info;
 429         struct segment_info *entry;
 430
 431         if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
 432                 return -EINVAL;
 433         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 434
 435         down_write(&dcssblk_devices_sem);
 436         if (inbuf[0] == '1') {
 437                 if (atomic_read(&dev_info->use_count) == 0) {
 438                         // device is idle => we save immediately
 439                         pr_info("All DCSSs that map to device %s are "
 440                                 "saved\n", dev_info->segment_name);
 441                         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 442                                 if (entry->segment_type == SEG_TYPE_EN ||
 443                                     entry->segment_type == SEG_TYPE_SN)
 444                                         pr_warn("DCSS %s is of type SN or EN"
 445                                                 " and cannot be saved\n",
 446                                                 entry->segment_name);
 447                                 else
 448                                         segment_save(entry->segment_name);
 449                         }
 450                 }  else {
 451                         // device is busy => we save it when it becomes
 452                         // idle in dcssblk_release
 453                         pr_info("Device %s is in use, its DCSSs will be "
 454                                 "saved when it becomes idle\n",
 455                                 dev_info->segment_name);
 456                         dev_info->save_pending = 1;
 457                 }
 458         } else if (inbuf[0] == '0') {
 459                 if (dev_info->save_pending) {
 460                         // device is busy & the user wants to undo his save
 461                         // request
 462                         dev_info->save_pending = 0;
 463                         pr_info("A pending save request for device %s "
 464                                 "has been canceled\n",
 465                                 dev_info->segment_name);
 466                 }
 467         } else {
 468                 up_write(&dcssblk_devices_sem);
 469                 return -EINVAL;
 470         }
 471         up_write(&dcssblk_devices_sem);
 472         return count;
 473 }
 474 static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
 475                    dcssblk_save_store);
 476
 477 /*
 478  * device attribute for showing all segments in a device
 479  */
 480 static ssize_t
 481 dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
 482                 char *buf)
 483 {
 484         int i;
 485
 486         struct dcssblk_dev_info *dev_info;
 487         struct segment_info *entry;
 488
 489         down_read(&dcssblk_devices_sem);
 490         dev_info = container_of(dev, struct dcssblk_dev_info, dev);
 491         i = 0;
 492         buf[0] = '\0';
 493         list_for_each_entry(entry, &dev_info->seg_list, lh) {
 494                 strcpy(&buf[i], entry->segment_name);
 495                 i += strlen(entry->segment_name);
 496                 buf[i] = '\n';
 497                 i++;
 498         }
 499         up_read(&dcssblk_devices_sem);
 500         return i;
 501 }
 502 static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
 503
 504 static struct attribute *dcssblk_dev_attrs[] = {
 505         &dev_attr_shared.attr,
 506         &dev_attr_save.attr,
 507         &dev_attr_seglist.attr,
 508         NULL,
 509 };
 510 static struct attribute_group dcssblk_dev_attr_group = {
 511         .attrs = dcssblk_dev_attrs,
 512 };
 513 static const struct attribute_group *dcssblk_dev_attr_groups[] = {
 514         &dcssblk_dev_attr_group,
 515         NULL,
 516 };
 517
 518 /*
 519  * device attribute for adding devices
 520  */
 521 static ssize_t
 522 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 523 {
 524         int rc, i, j, num_of_segments;
 525         struct dcssblk_dev_info *dev_info;
 526         struct segment_info *seg_info, *temp;
 527         char *local_buf;
 528         unsigned long seg_byte_size;
 529
 530         dev_info = NULL;
 531         seg_info = NULL;
 532         if (dev != dcssblk_root_dev) {
 533                 rc = -EINVAL;
 534                 goto out_nobuf;
 535         }
 536         if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
 537                 rc = -ENAMETOOLONG;
 538                 goto out_nobuf;
 539         }
 540
 541         local_buf = kmalloc(count + 1, GFP_KERNEL);
 542         if (local_buf == NULL) {
 543                 rc = -ENOMEM;
 544                 goto out_nobuf;
 545         }
 546
 547         /*
 548          * parse input
 549          */
 550         num_of_segments = 0;
 551         for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
 552                 for (j = i; j < count &&
 553                         (buf[j] != ':') &&
 554                         (buf[j] != '\0') &&
 555                         (buf[j] != '\n'); j++) {
 556                         local_buf[j-i] = toupper(buf[j]);
 557                 }
 558                 local_buf[j-i] = '\0';
 559                 if (((j - i) == 0) || ((j - i) > 8)) {
 560                         rc = -ENAMETOOLONG;
 561                         goto seg_list_del;
 562                 }
 563
 564                 rc = dcssblk_load_segment(local_buf, &seg_info);
 565                 if (rc < 0)
 566                         goto seg_list_del;
 567                 /*
 568                  * get a struct dcssblk_dev_info
 569                  */
 570                 if (num_of_segments == 0) {
 571                         dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
 572                                         GFP_KERNEL);
 573                         if (dev_info == NULL) {
 574                                 rc = -ENOMEM;
 575                                 goto out;
 576                         }
 577                         strcpy(dev_info->segment_name, local_buf);
 578                         dev_info->segment_type = seg_info->segment_type;
 579                         INIT_LIST_HEAD(&dev_info->seg_list);
 580                 }
 581                 list_add_tail(&seg_info->lh, &dev_info->seg_list);
 582                 num_of_segments++;
 583                 i = j;
 584
 585                 if ((buf[j] == '\0') || (buf[j] == '\n'))
 586                         break;
 587         }
 588
 589         /* no trailing colon at the end of the input */
 590         if ((i > 0) && (buf[i-1] == ':')) {
 591                 rc = -ENAMETOOLONG;
 592                 goto seg_list_del;
 593         }
 594         strlcpy(local_buf, buf, i + 1);
 595         dev_info->num_of_segments = num_of_segments;
 596         rc = dcssblk_is_continuous(dev_info);
 597         if (rc < 0)
 598                 goto seg_list_del;
 599
 600         dev_info->start = dcssblk_find_lowest_addr(dev_info);
 601         dev_info->end = dcssblk_find_highest_addr(dev_info);
 602
 603         dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
 604         dev_info->dev.release = dcssblk_release_segment;
 605         dev_info->dev.groups = dcssblk_dev_attr_groups;
 606         INIT_LIST_HEAD(&dev_info->lh);
 607         dev_info->gd = alloc_disk(DCSSBLK_MINORS_PER_DISK);
 608         if (dev_info->gd == NULL) {
 609                 rc = -ENOMEM;
 610                 goto seg_list_del;
 611         }
 612         dev_info->gd->major = dcssblk_major;
 613         dev_info->gd->fops = &dcssblk_devops;
 614         dev_info->dcssblk_queue = blk_alloc_queue(GFP_KERNEL);
 615         dev_info->gd->queue = dev_info->dcssblk_queue;
 616         dev_info->gd->private_data = dev_info;
 617         dev_info->gd->driverfs_dev = &dev_info->dev;
 618         blk_queue_make_request(dev_info->dcssblk_queue, dcssblk_make_request);
 619         blk_queue_logical_block_size(dev_info->dcssblk_queue, 4096);
 620
 621         seg_byte_size = (dev_info->end - dev_info->start + 1);
 622         set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
 623         pr_info("Loaded %s with total size %lu bytes and capacity %lu "
 624                 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
 625
 626         dev_info->save_pending = 0;
 627         dev_info->is_shared = 1;
 628         dev_info->dev.parent = dcssblk_root_dev;
 629
 630         /*
 631          *get minor, add to list
 632          */
 633         down_write(&dcssblk_devices_sem);
 634         if (dcssblk_get_segment_by_name(local_buf)) {
 635                 rc = -EEXIST;
 636                 goto release_gd;
 637         }
 638         rc = dcssblk_assign_free_minor(dev_info);
 639         if (rc)
 640                 goto release_gd;
 641         sprintf(dev_info->gd->disk_name, "dcssblk%d",
 642                 dev_info->gd->first_minor);
 643         list_add_tail(&dev_info->lh, &dcssblk_devices);
 644
 645         if (!try_module_get(THIS_MODULE)) {
 646                 rc = -ENODEV;
 647                 goto dev_list_del;
 648         }
 649         /*
 650          * register the device
 651          */
 652         rc = device_register(&dev_info->dev);
 653         if (rc)
 654                 goto put_dev;
 655
 656         get_device(&dev_info->dev);
 657         add_disk(dev_info->gd);
 658
 659         switch (dev_info->segment_type) {
 660                 case SEG_TYPE_SR:
 661                 case SEG_TYPE_ER:
 662                 case SEG_TYPE_SC:
 663                         set_disk_ro(dev_info->gd,1);
 664                         break;
 665                 default:
 666                         set_disk_ro(dev_info->gd,0);
 667                         break;
 668         }
 669         up_write(&dcssblk_devices_sem);
 670         rc = count;
 671         goto out;
 672
 673 put_dev:
 674         list_del(&dev_info->lh);
 675         blk_cleanup_queue(dev_info->dcssblk_queue);
 676         dev_info->gd->queue = NULL;
 677         put_disk(dev_info->gd);
 678         list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
 679                 segment_unload(seg_info->segment_name);
 680         }
 681         put_device(&dev_info->dev);
 682         up_write(&dcssblk_devices_sem);
 683         goto out;
 684 dev_list_del:
 685         list_del(&dev_info->lh);
 686 release_gd:
 687         blk_cleanup_queue(dev_info->dcssblk_queue);
 688         dev_info->gd->queue = NULL;
 689         put_disk(dev_info->gd);
 690         up_write(&dcssblk_devices_sem);
 691 seg_list_del:
 692         if (dev_info == NULL)
 693                 goto out;
 694         list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
 695                 list_del(&seg_info->lh);
 696                 segment_unload(seg_info->segment_name);
 697                 kfree(seg_info);
 698         }
 699         kfree(dev_info);
 700 out:
 701         kfree(local_buf);
 702 out_nobuf:
 703         return rc;
 704 }
 705
 706 /*
 707  * device attribute for removing devices
 708  */
 709 static ssize_t
 710 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 711 {
 712         struct dcssblk_dev_info *dev_info;
 713         struct segment_info *entry;
 714         int rc, i;
 715         char *local_buf;
 716
 717         if (dev != dcssblk_root_dev) {
 718                 return -EINVAL;
 719         }
 720         local_buf = kmalloc(count + 1, GFP_KERNEL);
 721         if (local_buf == NULL) {
 722                 return -ENOMEM;
 723         }
 724         /*
 725          * parse input
 726          */
 727         for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
 728                 local_buf[i] = toupper(buf[i]);
 729         }
 730         local_buf[i] = '\0';
 731         if ((i == 0) || (i > 8)) {
 732                 rc = -ENAMETOOLONG;
 733                 goto out_buf;
 734         }
 735
 736         down_write(&dcssblk_devices_sem);
 737         dev_info = dcssblk_get_device_by_name(local_buf);
 738         if (dev_info == NULL) {
 739                 up_write(&dcssblk_devices_sem);
 740                 pr_warning("Device %s cannot be removed because it is not a "
 741                            "known device\n", local_buf);
 742                 rc = -ENODEV;
 743                 goto out_buf;
 744         }
 745         if (atomic_read(&dev_info->use_count) != 0) {
 746                 up_write(&dcssblk_devices_sem);
 747                 pr_warning("Device %s cannot be removed while it is in "
 748                            "use\n", local_buf);
 749                 rc = -EBUSY;
 750                 goto out_buf;
 751         }
 752
 753         list_del(&dev_info->lh);
 754         del_gendisk(dev_info->gd);
 755         blk_cleanup_queue(dev_info->dcssblk_queue);
 756         dev_info->gd->queue = NULL;
 757         put_disk(dev_info->gd);
 758         device_unregister(&dev_info->dev);
 759
 760         /* unload all related segments */
 761         list_for_each_entry(entry, &dev_info->seg_list, lh)
 762                 segment_unload(entry->segment_name);
 763
 764         put_device(&dev_info->dev);
 765         up_write(&dcssblk_devices_sem);
 766
 767         rc = count;
 768 out_buf:
 769         kfree(local_buf);
 770         return rc;
 771 }
 772
 773 static int
 774 dcssblk_open(struct block_device *bdev, fmode_t mode)
 775 {
 776         struct dcssblk_dev_info *dev_info;
 777         int rc;
 778
 779         dev_info = bdev->bd_disk->private_data;
 780         if (NULL == dev_info) {
 781                 rc = -ENODEV;
 782                 goto out;
 783         }
 784         atomic_inc(&dev_info->use_count);
 785         bdev->bd_block_size = 4096;
 786         rc = 0;
 787 out:
 788         return rc;
 789 }
 790
 791 static void
 792 dcssblk_release(struct gendisk *disk, fmode_t mode)
 793 {
 794         struct dcssblk_dev_info *dev_info = disk->private_data;
 795         struct segment_info *entry;
 796
 797         if (!dev_info) {
 798                 WARN_ON(1);
 799                 return;
 800         }
 801         down_write(&dcssblk_devices_sem);
 802         if (atomic_dec_and_test(&dev_info->use_count)
 803             && (dev_info->save_pending)) {
 804                 pr_info("Device %s has become idle and is being saved "
 805                         "now\n", dev_info->segment_name);
 806                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 807                         if (entry->segment_type == SEG_TYPE_EN ||
 808                             entry->segment_type == SEG_TYPE_SN)
 809                                 pr_warn("DCSS %s is of type SN or EN and cannot"
 810                                         " be saved\n", entry->segment_name);
 811                         else
 812                                 segment_save(entry->segment_name);
 813                 }
 814                 dev_info->save_pending = 0;
 815         }
 816         up_write(&dcssblk_devices_sem);
 817 }
 818
 819 static blk_qc_t
 820 dcssblk_make_request(struct request_queue *q, struct bio *bio)
 821 {
 822         struct dcssblk_dev_info *dev_info;
 823         struct bio_vec bvec;
 824         struct bvec_iter iter;
 825         unsigned long index;
 826         unsigned long page_addr;
 827         unsigned long source_addr;
 828         unsigned long bytes_done;
 829
 830         blk_queue_split(q, &bio, q->bio_split);
 831
 832         bytes_done = 0;
 833         dev_info = bio->bi_bdev->bd_disk->private_data;
 834         if (dev_info == NULL)
 835                 goto fail;
 836         if ((bio->bi_iter.bi_sector & 7) != 0 ||
 837             (bio->bi_iter.bi_size & 4095) != 0)
 838                 /* Request is not page-aligned. */
 839                 goto fail;
 840         if (bio_end_sector(bio) > get_capacity(bio->bi_bdev->bd_disk)) {
 841                 /* Request beyond end of DCSS segment. */
 842                 goto fail;
 843         }
 844         /* verify data transfer direction */
 845         if (dev_info->is_shared) {
 846                 switch (dev_info->segment_type) {
 847                 case SEG_TYPE_SR:
 848                 case SEG_TYPE_ER:
 849                 case SEG_TYPE_SC:
 850                         /* cannot write to these segments */
 851                         if (bio_data_dir(bio) == WRITE) {
 852                                 pr_warning("Writing to %s failed because it "
 853                                            "is a read-only device\n",
 854                                            dev_name(&dev_info->dev));
 855                                 goto fail;
 856                         }
 857                 }
 858         }
 859
 860         index = (bio->bi_iter.bi_sector >> 3);
 861         bio_for_each_segment(bvec, bio, iter) {
 862                 page_addr = (unsigned long)
 863                         page_address(bvec.bv_page) + bvec.bv_offset;
 864                 source_addr = dev_info->start + (index<<12) + bytes_done;
 865                 if (unlikely((page_addr & 4095) != 0) || (bvec.bv_len & 4095) != 0)
 866                         // More paranoia.
 867                         goto fail;
 868                 if (bio_data_dir(bio) == READ) {
 869                         memcpy((void*)page_addr, (void*)source_addr,
 870                                 bvec.bv_len);
 871                 } else {
 872                         memcpy((void*)source_addr, (void*)page_addr,
 873                                 bvec.bv_len);
 874                 }
 875                 bytes_done += bvec.bv_len;
 876         }
 877         bio_endio(bio);
 878         return BLK_QC_T_NONE;
 879 fail:
 880         bio_io_error(bio);
 881         return BLK_QC_T_NONE;
 882 }
 883
 884 static long
 885 dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
 886                         void __pmem **kaddr, unsigned long *pfn)
 887 {
 888         struct dcssblk_dev_info *dev_info;
 889         unsigned long offset, dev_sz;
 890         void *addr;
 891
 892         dev_info = bdev->bd_disk->private_data;
 893         if (!dev_info)
 894                 return -ENODEV;
 895         dev_sz = dev_info->end - dev_info->start;
 896         offset = secnum * 512;
 897         addr = (void *) (dev_info->start + offset);
 898         *pfn = virt_to_phys(addr) >> PAGE_SHIFT;
 899         *kaddr = (void __pmem *) addr;
 900
 901         return dev_sz - offset;
 902 }
 903
 904 static void
 905 dcssblk_check_params(void)
 906 {
 907         int rc, i, j, k;
 908         char buf[DCSSBLK_PARM_LEN + 1];
 909         struct dcssblk_dev_info *dev_info;
 910
 911         for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
 912              i++) {
 913                 for (j = i; (j < DCSSBLK_PARM_LEN) &&
 914                             (dcssblk_segments[j] != ',')  &&
 915                             (dcssblk_segments[j] != '\0') &&
 916                             (dcssblk_segments[j] != '('); j++)
 917                 {
 918                         buf[j-i] = dcssblk_segments[j];
 919                 }
 920                 buf[j-i] = '\0';
 921                 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
 922                 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
 923                         for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
 924                                 buf[k] = toupper(buf[k]);
 925                         buf[k] = '\0';
 926                         if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
 927                                 down_read(&dcssblk_devices_sem);
 928                                 dev_info = dcssblk_get_device_by_name(buf);
 929                                 up_read(&dcssblk_devices_sem);
 930                                 if (dev_info)
 931                                         dcssblk_shared_store(&dev_info->dev,
 932                                                              NULL, "0\n", 2);
 933                         }
 934                 }
 935                 while ((dcssblk_segments[j] != ',') &&
 936                        (dcssblk_segments[j] != '\0'))
 937                 {
 938                         j++;
 939                 }
 940                 if (dcssblk_segments[j] == '\0')
 941                         break;
 942                 i = j;
 943         }
 944 }
 945
 946 /*
 947  * Suspend / Resume
 948  */
 949 static int dcssblk_freeze(struct device *dev)
 950 {
 951         struct dcssblk_dev_info *dev_info;
 952         int rc = 0;
 953
 954         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 955                 switch (dev_info->segment_type) {
 956                         case SEG_TYPE_SR:
 957                         case SEG_TYPE_ER:
 958                         case SEG_TYPE_SC:
 959                                 if (!dev_info->is_shared)
 960                                         rc = -EINVAL;
 961                                 break;
 962                         default:
 963                                 rc = -EINVAL;
 964                                 break;
 965                 }
 966                 if (rc)
 967                         break;
 968         }
 969         if (rc)
 970                 pr_err("Suspending the system failed because DCSS device %s "
 971                        "is writable\n",
 972                        dev_info->segment_name);
 973         return rc;
 974 }
 975
 976 static int dcssblk_restore(struct device *dev)
 977 {
 978         struct dcssblk_dev_info *dev_info;
 979         struct segment_info *entry;
 980         unsigned long start, end;
 981         int rc = 0;
 982
 983         list_for_each_entry(dev_info, &dcssblk_devices, lh) {
 984                 list_for_each_entry(entry, &dev_info->seg_list, lh) {
 985                         segment_unload(entry->segment_name);
 986                         rc = segment_load(entry->segment_name, SEGMENT_SHARED,
 987                                           &start, &end);
 988                         if (rc < 0) {
 989 // TODO in_use check ?
 990                                 segment_warning(rc, entry->segment_name);
 991                                 goto out_panic;
 992                         }
 993                         if (start != entry->start || end != entry->end) {
 994                                 pr_err("The address range of DCSS %s changed "
 995                                        "while the system was suspended\n",
 996                                        entry->segment_name);
 997                                 goto out_panic;
 998                         }
 999                 }
1000         }
1001         return 0;
1002 out_panic:
1003         panic("fatal dcssblk resume error\n");
1004 }
1005
1006 static int dcssblk_thaw(struct device *dev)
1007 {
1008         return 0;
1009 }
1010
1011 static const struct dev_pm_ops dcssblk_pm_ops = {
1012         .freeze         = dcssblk_freeze,
1013         .thaw           = dcssblk_thaw,
1014         .restore        = dcssblk_restore,
1015 };
1016
1017 static struct platform_driver dcssblk_pdrv = {
1018         .driver = {
1019                 .name   = "dcssblk",
1020                 .pm     = &dcssblk_pm_ops,
1021         },
1022 };
1023
1024 static struct platform_device *dcssblk_pdev;
1025
1026
1027 /*
1028  * The init/exit functions.
1029  */
1030 static void __exit
1031 dcssblk_exit(void)
1032 {
1033         platform_device_unregister(dcssblk_pdev);
1034         platform_driver_unregister(&dcssblk_pdrv);
1035         root_device_unregister(dcssblk_root_dev);
1036         unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
1037 }
1038
1039 static int __init
1040 dcssblk_init(void)
1041 {
1042         int rc;
1043
1044         rc = platform_driver_register(&dcssblk_pdrv);
1045         if (rc)
1046                 return rc;
1047
1048         dcssblk_pdev = platform_device_register_simple("dcssblk", -1, NULL,
1049                                                         0);
1050         if (IS_ERR(dcssblk_pdev)) {
1051                 rc = PTR_ERR(dcssblk_pdev);
1052                 goto out_pdrv;
1053         }
1054
1055         dcssblk_root_dev = root_device_register("dcssblk");
1056         if (IS_ERR(dcssblk_root_dev)) {
1057                 rc = PTR_ERR(dcssblk_root_dev);
1058                 goto out_pdev;
1059         }
1060         rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
1061         if (rc)
1062                 goto out_root;
1063         rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1064         if (rc)
1065                 goto out_root;
1066         rc = register_blkdev(0, DCSSBLK_NAME);
1067         if (rc < 0)
1068                 goto out_root;
1069         dcssblk_major = rc;
1070         init_rwsem(&dcssblk_devices_sem);
1071
1072         dcssblk_check_params();
1073         return 0;
1074
1075 out_root:
1076         root_device_unregister(dcssblk_root_dev);
1077 out_pdev:
1078         platform_device_unregister(dcssblk_pdev);
1079 out_pdrv:
1080         platform_driver_unregister(&dcssblk_pdrv);
1081         return rc;
1082 }
1083
1084 module_init(dcssblk_init);
1085 module_exit(dcssblk_exit);
1086
1087 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1088 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1089                  "comma-separated list, names in each set separated "
1090                  "by commas are separated by colons, each set contains "
1091                  "names of contiguous segments and each name max. 8 chars.\n"
1092                  "Adding \"(local)\" to the end of each set equals echoing 0 "
1093                  "to /sys/devices/dcssblk/<device name>/shared after loading "
1094                  "the contiguous segments - \n"
1095                  "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1096
1097 MODULE_LICENSE("GPL");