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   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 #define KMSG_COMPONENT "xpram"
  29 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  30
  31 #include <linux/module.h>
  32 #include <linux/moduleparam.h>
  33 #include <linux/ctype.h>  /* isdigit, isxdigit */
  34 #include <linux/errno.h>
  35 #include <linux/init.h>
  36 #include <linux/slab.h>
  37 #include <linux/blkdev.h>
  38 #include <linux/blkpg.h>
  39 #include <linux/hdreg.h>  /* HDIO_GETGEO */
  40 #include <linux/sysdev.h>
  41 #include <linux/bio.h>
  42 #include <linux/suspend.h>
  43 #include <linux/platform_device.h>
  44 #include <asm/uaccess.h>
  45
  46 #define XPRAM_NAME      "xpram"
  47 #define XPRAM_DEVS      1       /* one partition */
  48 #define XPRAM_MAX_DEVS  32      /* maximal number of devices (partitions) */
  49
  50 typedef struct {
  51         unsigned int    size;           /* size of xpram segment in pages */
  52         unsigned int    offset;         /* start page of xpram segment */
  53 } xpram_device_t;
  54
  55 static xpram_device_t xpram_devices[XPRAM_MAX_DEVS];
  56 static unsigned int xpram_sizes[XPRAM_MAX_DEVS];
  57 static struct gendisk *xpram_disks[XPRAM_MAX_DEVS];
  58 static struct request_queue *xpram_queues[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                 return -ENXIO;
 105         if (cc == 1)
 106                 return -EIO;
 107         return 0;
 108 }
 109
 110 /*
 111  * Copy a 4kB page of main memory to an expanded memory page
 112  * Arguments
 113  *           page_addr:    address of source page
 114  *           xpage_index:  index of expandeded memory page
 115  * Return value
 116  *           0:            if operation succeeds
 117  *           -EIO:         if pgout failed
 118  *           -ENXIO:       if xpram has vanished
 119  */
 120 static long xpram_page_out (unsigned long page_addr, unsigned int xpage_index)
 121 {
 122         int cc = 2;     /* return unused cc 2 if pgin traps */
 123
 124         asm volatile(
 125                 "       .insn   rre,0xb22f0000,%1,%2\n"  /* pgout %1,%2 */
 126                 "0:     ipm     %0\n"
 127                 "       srl     %0,28\n"
 128                 "1:\n"
 129                 EX_TABLE(0b,1b)
 130                 : "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
 131         if (cc == 3)
 132                 return -ENXIO;
 133         if (cc == 2)
 134                 return -ENXIO;
 135         if (cc == 1)
 136                 return -EIO;
 137         return 0;
 138 }
 139
 140 /*
 141  * Check if xpram is available.
 142  */
 143 static int xpram_present(void)
 144 {
 145         unsigned long mem_page;
 146         int rc;
 147
 148         mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
 149         if (!mem_page)
 150                 return -ENOMEM;
 151         rc = xpram_page_in(mem_page, 0);
 152         free_page(mem_page);
 153         return rc ? -ENXIO : 0;
 154 }
 155
 156 /*
 157  * Return index of the last available xpram page.
 158  */
 159 static unsigned long xpram_highest_page_index(void)
 160 {
 161         unsigned int page_index, add_bit;
 162         unsigned long mem_page;
 163
 164         mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
 165         if (!mem_page)
 166                 return 0;
 167
 168         page_index = 0;
 169         add_bit = 1ULL << (sizeof(unsigned int)*8 - 1);
 170         while (add_bit > 0) {
 171                 if (xpram_page_in(mem_page, page_index | add_bit) == 0)
 172                         page_index |= add_bit;
 173                 add_bit >>= 1;
 174         }
 175
 176         free_page (mem_page);
 177
 178         return page_index;
 179 }
 180
 181 /*
 182  * Block device make request function.
 183  */
 184 static int xpram_make_request(struct request_queue *q, struct bio *bio)
 185 {
 186         xpram_device_t *xdev = bio->bi_bdev->bd_disk->private_data;
 187         struct bio_vec *bvec;
 188         unsigned int index;
 189         unsigned long page_addr;
 190         unsigned long bytes;
 191         int i;
 192
 193         if ((bio->bi_sector & 7) != 0 || (bio->bi_size & 4095) != 0)
 194                 /* Request is not page-aligned. */
 195                 goto fail;
 196         if ((bio->bi_size >> 12) > xdev->size)
 197                 /* Request size is no page-aligned. */
 198                 goto fail;
 199         if ((bio->bi_sector >> 3) > 0xffffffffU - xdev->offset)
 200                 goto fail;
 201         index = (bio->bi_sector >> 3) + xdev->offset;
 202         bio_for_each_segment(bvec, bio, i) {
 203                 page_addr = (unsigned long)
 204                         kmap(bvec->bv_page) + bvec->bv_offset;
 205                 bytes = bvec->bv_len;
 206                 if ((page_addr & 4095) != 0 || (bytes & 4095) != 0)
 207                         /* More paranoia. */
 208                         goto fail;
 209                 while (bytes > 0) {
 210                         if (bio_data_dir(bio) == READ) {
 211                                 if (xpram_page_in(page_addr, index) != 0)
 212                                         goto fail;
 213                         } else {
 214                                 if (xpram_page_out(page_addr, index) != 0)
 215                                         goto fail;
 216                         }
 217                         page_addr += 4096;
 218                         bytes -= 4096;
 219                         index++;
 220                 }
 221         }
 222         set_bit(BIO_UPTODATE, &bio->bi_flags);
 223         bio_endio(bio, 0);
 224         return 0;
 225 fail:
 226         bio_io_error(bio);
 227         return 0;
 228 }
 229
 230 static int xpram_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 231 {
 232         unsigned long size;
 233
 234         /*
 235          * get geometry: we have to fake one...  trim the size to a
 236          * multiple of 64 (32k): tell we have 16 sectors, 4 heads,
 237          * whatever cylinders. Tell also that data starts at sector. 4.
 238          */
 239         size = (xpram_pages * 8) & ~0x3f;
 240         geo->cylinders = size >> 6;
 241         geo->heads = 4;
 242         geo->sectors = 16;
 243         geo->start = 4;
 244         return 0;
 245 }
 246
 247 static const struct block_device_operations xpram_devops =
 248 {
 249         .owner  = THIS_MODULE,
 250         .getgeo = xpram_getgeo,
 251 };
 252
 253 /*
 254  * Setup xpram_sizes array.
 255  */
 256 static int __init xpram_setup_sizes(unsigned long pages)
 257 {
 258         unsigned long mem_needed;
 259         unsigned long mem_auto;
 260         unsigned long long size;
 261         int mem_auto_no;
 262         int i;
 263
 264         /* Check number of devices. */
 265         if (devs <= 0 || devs > XPRAM_MAX_DEVS) {
 266                 pr_err("%d is not a valid number of XPRAM devices\n",devs);
 267                 return -EINVAL;
 268         }
 269         xpram_devs = devs;
 270
 271         /*
 272          * Copy sizes array to xpram_sizes and align partition
 273          * sizes to page boundary.
 274          */
 275         mem_needed = 0;
 276         mem_auto_no = 0;
 277         for (i = 0; i < xpram_devs; i++) {
 278                 if (sizes[i]) {
 279                         size = simple_strtoull(sizes[i], &sizes[i], 0);
 280                         switch (sizes[i][0]) {
 281                         case 'g':
 282                         case 'G':
 283                                 size <<= 20;
 284                                 break;
 285                         case 'm':
 286                         case 'M':
 287                                 size <<= 10;
 288                         }
 289                         xpram_sizes[i] = (size + 3) & -4UL;
 290                 }
 291                 if (xpram_sizes[i])
 292                         mem_needed += xpram_sizes[i];
 293                 else
 294                         mem_auto_no++;
 295         }
 296
 297         pr_info("  number of devices (partitions): %d \n", xpram_devs);
 298         for (i = 0; i < xpram_devs; i++) {
 299                 if (xpram_sizes[i])
 300                         pr_info("  size of partition %d: %u kB\n",
 301                                 i, xpram_sizes[i]);
 302                 else
 303                         pr_info("  size of partition %d to be set "
 304                                 "automatically\n",i);
 305         }
 306         pr_info("  memory needed (for sized partitions): %lu kB\n",
 307                 mem_needed);
 308         pr_info("  partitions to be sized automatically: %d\n",
 309                 mem_auto_no);
 310
 311         if (mem_needed > pages * 4) {
 312                 pr_err("Not enough expanded memory available\n");
 313                 return -EINVAL;
 314         }
 315
 316         /*
 317          * partitioning:
 318          * xpram_sizes[i] != 0; partition i has size xpram_sizes[i] kB
 319          * else:             ; all partitions with zero xpram_sizes[i]
 320          *                     partition equally the remaining space
 321          */
 322         if (mem_auto_no) {
 323                 mem_auto = ((pages - mem_needed / 4) / mem_auto_no) * 4;
 324                 pr_info("  automatically determined "
 325                         "partition size: %lu kB\n", mem_auto);
 326                 for (i = 0; i < xpram_devs; i++)
 327                         if (xpram_sizes[i] == 0)
 328                                 xpram_sizes[i] = mem_auto;
 329         }
 330         return 0;
 331 }
 332
 333 static int __init xpram_setup_blkdev(void)
 334 {
 335         unsigned long offset;
 336         int i, rc = -ENOMEM;
 337
 338         for (i = 0; i < xpram_devs; i++) {
 339                 xpram_disks[i] = alloc_disk(1);
 340                 if (!xpram_disks[i])
 341                         goto out;
 342                 xpram_queues[i] = blk_alloc_queue(GFP_KERNEL);
 343                 if (!xpram_queues[i]) {
 344                         put_disk(xpram_disks[i]);
 345                         goto out;
 346                 }
 347                 blk_queue_make_request(xpram_queues[i], xpram_make_request);
 348                 blk_queue_logical_block_size(xpram_queues[i], 4096);
 349         }
 350
 351         /*
 352          * Register xpram major.
 353          */
 354         rc = register_blkdev(XPRAM_MAJOR, XPRAM_NAME);
 355         if (rc < 0)
 356                 goto out;
 357
 358         /*
 359          * Setup device structures.
 360          */
 361         offset = 0;
 362         for (i = 0; i < xpram_devs; i++) {
 363                 struct gendisk *disk = xpram_disks[i];
 364
 365                 xpram_devices[i].size = xpram_sizes[i] / 4;
 366                 xpram_devices[i].offset = offset;
 367                 offset += xpram_devices[i].size;
 368                 disk->major = XPRAM_MAJOR;
 369                 disk->first_minor = i;
 370                 disk->fops = &xpram_devops;
 371                 disk->private_data = &xpram_devices[i];
 372                 disk->queue = xpram_queues[i];
 373                 sprintf(disk->disk_name, "slram%d", i);
 374                 set_capacity(disk, xpram_sizes[i] << 1);
 375                 add_disk(disk);
 376         }
 377
 378         return 0;
 379 out:
 380         while (i--) {
 381                 blk_cleanup_queue(xpram_queues[i]);
 382                 put_disk(xpram_disks[i]);
 383         }
 384         return rc;
 385 }
 386
 387 /*
 388  * Resume failed: Print error message and call panic.
 389  */
 390 static void xpram_resume_error(const char *message)
 391 {
 392         pr_err("Resuming the system failed: %s\n", message);
 393         panic("xpram resume error\n");
 394 }
 395
 396 /*
 397  * Check if xpram setup changed between suspend and resume.
 398  */
 399 static int xpram_restore(struct device *dev)
 400 {
 401         if (!xpram_pages)
 402                 return 0;
 403         if (xpram_present() != 0)
 404                 xpram_resume_error("xpram disappeared");
 405         if (xpram_pages != xpram_highest_page_index() + 1)
 406                 xpram_resume_error("Size of xpram changed");
 407         return 0;
 408 }
 409
 410 static struct dev_pm_ops xpram_pm_ops = {
 411         .restore        = xpram_restore,
 412 };
 413
 414 static struct platform_driver xpram_pdrv = {
 415         .driver = {
 416                 .name   = XPRAM_NAME,
 417                 .owner  = THIS_MODULE,
 418                 .pm     = &xpram_pm_ops,
 419         },
 420 };
 421
 422 static struct platform_device *xpram_pdev;
 423
 424 /*
 425  * Finally, the init/exit functions.
 426  */
 427 static void __exit xpram_exit(void)
 428 {
 429         int i;
 430         for (i = 0; i < xpram_devs; i++) {
 431                 del_gendisk(xpram_disks[i]);
 432                 blk_cleanup_queue(xpram_queues[i]);
 433                 put_disk(xpram_disks[i]);
 434         }
 435         unregister_blkdev(XPRAM_MAJOR, XPRAM_NAME);
 436         platform_device_unregister(xpram_pdev);
 437         platform_driver_unregister(&xpram_pdrv);
 438 }
 439
 440 static int __init xpram_init(void)
 441 {
 442         int rc;
 443
 444         /* Find out size of expanded memory. */
 445         if (xpram_present() != 0) {
 446                 pr_err("No expanded memory available\n");
 447                 return -ENODEV;
 448         }
 449         xpram_pages = xpram_highest_page_index() + 1;
 450         pr_info("  %u pages expanded memory found (%lu KB).\n",
 451                 xpram_pages, (unsigned long) xpram_pages*4);
 452         rc = xpram_setup_sizes(xpram_pages);
 453         if (rc)
 454                 return rc;
 455         rc = platform_driver_register(&xpram_pdrv);
 456         if (rc)
 457                 return rc;
 458         xpram_pdev = platform_device_register_simple(XPRAM_NAME, -1, NULL, 0);
 459         if (IS_ERR(xpram_pdev)) {
 460                 rc = PTR_ERR(xpram_pdev);
 461                 goto fail_platform_driver_unregister;
 462         }
 463         rc = xpram_setup_blkdev();
 464         if (rc)
 465                 goto fail_platform_device_unregister;
 466         return 0;
 467
 468 fail_platform_device_unregister:
 469         platform_device_unregister(xpram_pdev);
 470 fail_platform_driver_unregister:
 471         platform_driver_unregister(&xpram_pdrv);
 472         return rc;
 473 }
 474
 475 module_init(xpram_init);
 476 module_exit(xpram_exit);