drivers/s390/block/xpram.c

   1 /*
   2  * Xpram.c -- the S/390 expanded memory RAM-disk
   3  *
   4  * significant parts of this code are based on
   5  * the sbull device driver presented in
   6  * A. Rubini: Linux Device Drivers
   7  *
   8  * Author of XPRAM specific coding: Reinhard Buendgen
   9  *                                  buendgen@de.ibm.com
  10  * Rewrite for 2.5: Martin Schwidefsky <schwidefsky@de.ibm.com>
  11  *
  12  * External interfaces:
  13  *   Interfaces to linux kernel
  14  *        xpram_setup: read kernel parameters
  15  *   Device specific file operations
  16  *        xpram_iotcl
  17  *        xpram_open
  18  *
  19  * "ad-hoc" partitioning:
  20  *    the expanded memory can be partitioned among several devices
  21  *    (with different minors). The partitioning set up can be
  22  *    set by kernel or module parameters (int devs & int sizes[])
  23  *
  24  * Potential future improvements:
  25  *   generic hard disk support to replace ad-hoc partitioning
  26  */
  27
  28 #include <linux/module.h>
  29 #include <linux/moduleparam.h>
  30 #include <linux/ctype.h>  /* isdigit, isxdigit */
  31 #include <linux/errno.h>
  32 #include <linux/init.h>
  33 #include <linux/slab.h>
  34 #include <linux/blkdev.h>
  35 #include <linux/blkpg.h>
  36 #include <linux/hdreg.h>  /* HDIO_GETGEO */
  37 #include <linux/sysdev.h>
  38 #include <linux/bio.h>
  39 #include <asm/uaccess.h>
  40
  41 #define XPRAM_NAME      "xpram"
  42 #define XPRAM_DEVS      1       /* one partition */
  43 #define XPRAM_MAX_DEVS  32      /* maximal number of devices (partitions) */
  44
  45 #define PRINT_DEBUG(x...)       printk(KERN_DEBUG XPRAM_NAME " debug:" x)
  46 #define PRINT_INFO(x...)        printk(KERN_INFO XPRAM_NAME " info:" x)
  47 #define PRINT_WARN(x...)        printk(KERN_WARNING XPRAM_NAME " warning:" x)
  48 #define PRINT_ERR(x...)         printk(KERN_ERR XPRAM_NAME " error:" x)
  49
  50
  51 typedef struct {
  52         unsigned int    size;           /* size of xpram segment in pages */
  53         unsigned int    offset;         /* start page of xpram segment */
  54 } xpram_device_t;
  55
  56 static xpram_device_t xpram_devices[XPRAM_MAX_DEVS];
  57 static unsigned int xpram_sizes[XPRAM_MAX_DEVS];
  58 static struct gendisk *xpram_disks[XPRAM_MAX_DEVS];
  59 static unsigned int xpram_pages;
  60 static int xpram_devs;
  61
  62 /*
  63  * Parameter parsing functions.
  64  */
  65 static int __initdata devs = XPRAM_DEVS;
  66 static char __initdata *sizes[XPRAM_MAX_DEVS];
  67
  68 module_param(devs, int, 0);
  69 module_param_array(sizes, charp, NULL, 0);
  70
  71 MODULE_PARM_DESC(devs, "number of devices (\"partitions\"), " \
  72                  "the default is " __MODULE_STRING(XPRAM_DEVS) "\n");
  73 MODULE_PARM_DESC(sizes, "list of device (partition) sizes " \
  74                  "the defaults are 0s \n" \
  75                  "All devices with size 0 equally partition the "
  76                  "remaining space on the expanded strorage not "
  77                  "claimed by explicit sizes\n");
  78 MODULE_LICENSE("GPL");
  79
  80 /*
  81  * Copy expanded memory page (4kB) into main memory
  82  * Arguments
  83  *           page_addr:    address of target page
  84  *           xpage_index:  index of expandeded memory page
  85  * Return value
  86  *           0:            if operation succeeds
  87  *           -EIO:         if pgin failed
  88  *           -ENXIO:       if xpram has vanished
  89  */
  90 static int xpram_page_in (unsigned long page_addr, unsigned int xpage_index)
  91 {
  92         int cc = 2;     /* return unused cc 2 if pgin traps */
  93
  94         asm volatile(
  95                 "       .insn   rre,0xb22e0000,%1,%2\n"  /* pgin %1,%2 */
  96                 "0:     ipm     %0\n"
  97                 "       srl     %0,28\n"
  98                 "1:\n"
  99                 EX_TABLE(0b,1b)
 100                 : "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
 101         if (cc == 3)
 102                 return -ENXIO;
 103         if (cc == 2) {
 104                 PRINT_ERR("expanded storage lost!\n");
 105                 return -ENXIO;
 106         }
 107         if (cc == 1) {
 108                 PRINT_ERR("page in failed for page index %u.\n",
 109                           xpage_index);
 110                 return -EIO;
 111         }
 112         return 0;
 113 }
 114
 115 /*
 116  * Copy a 4kB page of main memory to an expanded memory page
 117  * Arguments
 118  *           page_addr:    address of source page
 119  *           xpage_index:  index of expandeded memory page
 120  * Return value
 121  *           0:            if operation succeeds
 122  *           -EIO:         if pgout failed
 123  *           -ENXIO:       if xpram has vanished
 124  */
 125 static long xpram_page_out (unsigned long page_addr, unsigned int xpage_index)
 126 {
 127         int cc = 2;     /* return unused cc 2 if pgin traps */
 128
 129         asm volatile(
 130                 "       .insn   rre,0xb22f0000,%1,%2\n"  /* pgout %1,%2 */
 131                 "0:     ipm     %0\n"
 132                 "       srl     %0,28\n"
 133                 "1:\n"
 134                 EX_TABLE(0b,1b)
 135                 : "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
 136         if (cc == 3)
 137                 return -ENXIO;
 138         if (cc == 2) {
 139                 PRINT_ERR("expanded storage lost!\n");
 140                 return -ENXIO;
 141         }
 142         if (cc == 1) {
 143                 PRINT_ERR("page out failed for page index %u.\n",
 144                           xpage_index);
 145                 return -EIO;
 146         }
 147         return 0;
 148 }
 149
 150 /*
 151  * Check if xpram is available.
 152  */
 153 static int __init xpram_present(void)
 154 {
 155         unsigned long mem_page;
 156         int rc;
 157
 158         mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
 159         if (!mem_page)
 160                 return -ENOMEM;
 161         rc = xpram_page_in(mem_page, 0);
 162         free_page(mem_page);
 163         return rc ? -ENXIO : 0;
 164 }
 165
 166 /*
 167  * Return index of the last available xpram page.
 168  */
 169 static unsigned long __init xpram_highest_page_index(void)
 170 {
 171         unsigned int page_index, add_bit;
 172         unsigned long mem_page;
 173
 174         mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
 175         if (!mem_page)
 176                 return 0;
 177
 178         page_index = 0;
 179         add_bit = 1ULL << (sizeof(unsigned int)*8 - 1);
 180         while (add_bit > 0) {
 181                 if (xpram_page_in(mem_page, page_index | add_bit) == 0)
 182                         page_index |= add_bit;
 183                 add_bit >>= 1;
 184         }
 185
 186         free_page (mem_page);
 187
 188         return page_index;
 189 }
 190
 191 /*
 192  * Block device make request function.
 193  */
 194 static int xpram_make_request(request_queue_t *q, struct bio *bio)
 195 {
 196         xpram_device_t *xdev = bio->bi_bdev->bd_disk->private_data;
 197         struct bio_vec *bvec;
 198         unsigned int index;
 199         unsigned long page_addr;
 200         unsigned long bytes;
 201         int i;
 202
 203         if ((bio->bi_sector & 7) != 0 || (bio->bi_size & 4095) != 0)
 204                 /* Request is not page-aligned. */
 205                 goto fail;
 206         if ((bio->bi_size >> 12) > xdev->size)
 207                 /* Request size is no page-aligned. */
 208                 goto fail;
 209         if ((bio->bi_sector >> 3) > 0xffffffffU - xdev->offset)
 210                 goto fail;
 211         index = (bio->bi_sector >> 3) + xdev->offset;
 212         bio_for_each_segment(bvec, bio, i) {
 213                 page_addr = (unsigned long)
 214                         kmap(bvec->bv_page) + bvec->bv_offset;
 215                 bytes = bvec->bv_len;
 216                 if ((page_addr & 4095) != 0 || (bytes & 4095) != 0)
 217                         /* More paranoia. */
 218                         goto fail;
 219                 while (bytes > 0) {
 220                         if (bio_data_dir(bio) == READ) {
 221                                 if (xpram_page_in(page_addr, index) != 0)
 222                                         goto fail;
 223                         } else {
 224                                 if (xpram_page_out(page_addr, index) != 0)
 225                                         goto fail;
 226                         }
 227                         page_addr += 4096;
 228                         bytes -= 4096;
 229                         index++;
 230                 }
 231         }
 232         set_bit(BIO_UPTODATE, &bio->bi_flags);
 233         bytes = bio->bi_size;
 234         bio->bi_size = 0;
 235         bio->bi_end_io(bio, bytes, 0);
 236         return 0;
 237 fail:
 238         bio_io_error(bio, bio->bi_size);
 239         return 0;
 240 }
 241
 242 static int xpram_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 243 {
 244         unsigned long size;
 245
 246         /*
 247          * get geometry: we have to fake one...  trim the size to a
 248          * multiple of 64 (32k): tell we have 16 sectors, 4 heads,
 249          * whatever cylinders. Tell also that data starts at sector. 4.
 250          */
 251         size = (xpram_pages * 8) & ~0x3f;
 252         geo->cylinders = size >> 6;
 253         geo->heads = 4;
 254         geo->sectors = 16;
 255         geo->start = 4;
 256         return 0;
 257 }
 258
 259 static struct block_device_operations xpram_devops =
 260 {
 261         .owner  = THIS_MODULE,
 262         .getgeo = xpram_getgeo,
 263 };
 264
 265 /*
 266  * Setup xpram_sizes array.
 267  */
 268 static int __init xpram_setup_sizes(unsigned long pages)
 269 {
 270         unsigned long mem_needed;
 271         unsigned long mem_auto;
 272         unsigned long long size;
 273         int mem_auto_no;
 274         int i;
 275
 276         /* Check number of devices. */
 277         if (devs <= 0 || devs > XPRAM_MAX_DEVS) {
 278                 PRINT_ERR("invalid number %d of devices\n",devs);
 279                 return -EINVAL;
 280         }
 281         xpram_devs = devs;
 282
 283         /*
 284          * Copy sizes array to xpram_sizes and align partition
 285          * sizes to page boundary.
 286          */
 287         mem_needed = 0;
 288         mem_auto_no = 0;
 289         for (i = 0; i < xpram_devs; i++) {
 290                 if (sizes[i]) {
 291                         size = simple_strtoull(sizes[i], &sizes[i], 0);
 292                         switch (sizes[i][0]) {
 293                         case 'g':
 294                         case 'G':
 295                                 size <<= 20;
 296                                 break;
 297                         case 'm':
 298                         case 'M':
 299                                 size <<= 10;
 300                         }
 301                         xpram_sizes[i] = (size + 3) & -4UL;
 302                 }
 303                 if (xpram_sizes[i])
 304                         mem_needed += xpram_sizes[i];
 305                 else
 306                         mem_auto_no++;
 307         }
 308
 309         PRINT_INFO("  number of devices (partitions): %d \n", xpram_devs);
 310         for (i = 0; i < xpram_devs; i++) {
 311                 if (xpram_sizes[i])
 312                         PRINT_INFO("  size of partition %d: %u kB\n",
 313                                    i, xpram_sizes[i]);
 314                 else
 315                         PRINT_INFO("  size of partition %d to be set "
 316                                    "automatically\n",i);
 317         }
 318         PRINT_DEBUG("  memory needed (for sized partitions): %lu kB\n",
 319                     mem_needed);
 320         PRINT_DEBUG("  partitions to be sized automatically: %d\n",
 321                     mem_auto_no);
 322
 323         if (mem_needed > pages * 4) {
 324                 PRINT_ERR("Not enough expanded memory available\n");
 325                 return -EINVAL;
 326         }
 327
 328         /*
 329          * partitioning:
 330          * xpram_sizes[i] != 0; partition i has size xpram_sizes[i] kB
 331          * else:             ; all partitions with zero xpram_sizes[i]
 332          *                     partition equally the remaining space
 333          */
 334         if (mem_auto_no) {
 335                 mem_auto = ((pages - mem_needed / 4) / mem_auto_no) * 4;
 336                 PRINT_INFO("  automatically determined "
 337                            "partition size: %lu kB\n", mem_auto);
 338                 for (i = 0; i < xpram_devs; i++)
 339                         if (xpram_sizes[i] == 0)
 340                                 xpram_sizes[i] = mem_auto;
 341         }
 342         return 0;
 343 }
 344
 345 static struct request_queue *xpram_queue;
 346
 347 static int __init xpram_setup_blkdev(void)
 348 {
 349         unsigned long offset;
 350         int i, rc = -ENOMEM;
 351
 352         for (i = 0; i < xpram_devs; i++) {
 353                 struct gendisk *disk = alloc_disk(1);
 354                 if (!disk)
 355                         goto out;
 356                 xpram_disks[i] = disk;
 357         }
 358
 359         /*
 360          * Register xpram major.
 361          */
 362         rc = register_blkdev(XPRAM_MAJOR, XPRAM_NAME);
 363         if (rc < 0)
 364                 goto out;
 365
 366         /*
 367          * Assign the other needed values: make request function, sizes and
 368          * hardsect size. All the minor devices feature the same value.
 369          */
 370         xpram_queue = blk_alloc_queue(GFP_KERNEL);
 371         if (!xpram_queue) {
 372                 rc = -ENOMEM;
 373                 goto out_unreg;
 374         }
 375         blk_queue_make_request(xpram_queue, xpram_make_request);
 376         blk_queue_hardsect_size(xpram_queue, 4096);
 377
 378         /*
 379          * Setup device structures.
 380          */
 381         offset = 0;
 382         for (i = 0; i < xpram_devs; i++) {
 383                 struct gendisk *disk = xpram_disks[i];
 384
 385                 xpram_devices[i].size = xpram_sizes[i] / 4;
 386                 xpram_devices[i].offset = offset;
 387                 offset += xpram_devices[i].size;
 388                 disk->major = XPRAM_MAJOR;
 389                 disk->first_minor = i;
 390                 disk->fops = &xpram_devops;
 391                 disk->private_data = &xpram_devices[i];
 392                 disk->queue = xpram_queue;
 393                 sprintf(disk->disk_name, "slram%d", i);
 394                 set_capacity(disk, xpram_sizes[i] << 1);
 395                 add_disk(disk);
 396         }
 397
 398         return 0;
 399 out_unreg:
 400         unregister_blkdev(XPRAM_MAJOR, XPRAM_NAME);
 401 out:
 402         while (i--)
 403                 put_disk(xpram_disks[i]);
 404         return rc;
 405 }
 406
 407 /*
 408  * Finally, the init/exit functions.
 409  */
 410 static void __exit xpram_exit(void)
 411 {
 412         int i;
 413         for (i = 0; i < xpram_devs; i++) {
 414                 del_gendisk(xpram_disks[i]);
 415                 put_disk(xpram_disks[i]);
 416         }
 417         unregister_blkdev(XPRAM_MAJOR, XPRAM_NAME);
 418         blk_cleanup_queue(xpram_queue);
 419 }
 420
 421 static int __init xpram_init(void)
 422 {
 423         int rc;
 424
 425         /* Find out size of expanded memory. */
 426         if (xpram_present() != 0) {
 427                 PRINT_WARN("No expanded memory available\n");
 428                 return -ENODEV;
 429         }
 430         xpram_pages = xpram_highest_page_index() + 1;
 431         PRINT_INFO("  %u pages expanded memory found (%lu KB).\n",
 432                    xpram_pages, (unsigned long) xpram_pages*4);
 433         rc = xpram_setup_sizes(xpram_pages);
 434         if (rc)
 435                 return rc;
 436         return xpram_setup_blkdev();
 437 }
 438
 439 module_init(xpram_init);
 440 module_exit(xpram_exit);