drivers/s390/block/xpram.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Xpram.c -- the S/390 expanded memory RAM-disk
   4  *
   5  * significant parts of this code are based on
   6  * the sbull device driver presented in
   7  * A. Rubini: Linux Device Drivers
   8  *
   9  * Author of XPRAM specific coding: Reinhard Buendgen
  10  *                                  buendgen@de.ibm.com
  11  * Rewrite for 2.5: Martin Schwidefsky <schwidefsky@de.ibm.com>
  12  *
  13  * External interfaces:
  14  *   Interfaces to linux kernel
  15  *        xpram_setup: read kernel parameters
  16  *   Device specific file operations
  17  *        xpram_iotcl
  18  *        xpram_open
  19  *
  20  * "ad-hoc" partitioning:
  21  *    the expanded memory can be partitioned among several devices
  22  *    (with different minors). The partitioning set up can be
  23  *    set by kernel or module parameters (int devs & int sizes[])
  24  *
  25  * Potential future improvements:
  26  *   generic hard disk support to replace ad-hoc partitioning
  27  */
  28
  29 #define KMSG_COMPONENT "xpram"
  30 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  31
  32 #include <linux/module.h>
  33 #include <linux/moduleparam.h>
  34 #include <linux/ctype.h>  /* isdigit, isxdigit */
  35 #include <linux/errno.h>
  36 #include <linux/init.h>
  37 #include <linux/blkdev.h>
  38 #include <linux/blkpg.h>
  39 #include <linux/hdreg.h>  /* HDIO_GETGEO */
  40 #include <linux/device.h>
  41 #include <linux/bio.h>
  42 #include <linux/suspend.h>
  43 #include <linux/platform_device.h>
  44 #include <linux/gfp.h>
  45 #include <linux/uaccess.h>
  46
  47 #define XPRAM_NAME      "xpram"
  48 #define XPRAM_DEVS      1       /* one partition */
  49 #define XPRAM_MAX_DEVS  32      /* maximal number of devices (partitions) */
  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 struct request_queue *xpram_queues[XPRAM_MAX_DEVS];
  60 static unsigned int xpram_pages;
  61 static int xpram_devs;
  62
  63 /*
  64  * Parameter parsing functions.
  65  */
  66 static int devs = XPRAM_DEVS;
  67 static char *sizes[XPRAM_MAX_DEVS];
  68
  69 module_param(devs, int, 0);
  70 module_param_array(sizes, charp, NULL, 0);
  71
  72 MODULE_PARM_DESC(devs, "number of devices (\"partitions\"), " \
  73                  "the default is " __MODULE_STRING(XPRAM_DEVS) "\n");
  74 MODULE_PARM_DESC(sizes, "list of device (partition) sizes " \
  75                  "the defaults are 0s \n" \
  76                  "All devices with size 0 equally partition the "
  77                  "remaining space on the expanded strorage not "
  78                  "claimed by explicit sizes\n");
  79 MODULE_LICENSE("GPL");
  80
  81 /*
  82  * Copy expanded memory page (4kB) into main memory
  83  * Arguments
  84  *           page_addr:    address of target page
  85  *           xpage_index:  index of expandeded memory page
  86  * Return value
  87  *           0:            if operation succeeds
  88  *           -EIO:         if pgin failed
  89  *           -ENXIO:       if xpram has vanished
  90  */
  91 static int xpram_page_in (unsigned long page_addr, unsigned int xpage_index)
  92 {
  93         int cc = 2;     /* return unused cc 2 if pgin traps */
  94
  95         asm volatile(
  96                 "       .insn   rre,0xb22e0000,%1,%2\n"  /* pgin %1,%2 */
  97                 "0:     ipm     %0\n"
  98                 "       srl     %0,28\n"
  99                 "1:\n"
 100                 EX_TABLE(0b,1b)
 101                 : "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
 102         if (cc == 3)
 103                 return -ENXIO;
 104         if (cc == 2)
 105                 return -ENXIO;
 106         if (cc == 1)
 107                 return -EIO;
 108         return 0;
 109 }
 110
 111 /*
 112  * Copy a 4kB page of main memory to an expanded memory page
 113  * Arguments
 114  *           page_addr:    address of source page
 115  *           xpage_index:  index of expandeded memory page
 116  * Return value
 117  *           0:            if operation succeeds
 118  *           -EIO:         if pgout failed
 119  *           -ENXIO:       if xpram has vanished
 120  */
 121 static long xpram_page_out (unsigned long page_addr, unsigned int xpage_index)
 122 {
 123         int cc = 2;     /* return unused cc 2 if pgin traps */
 124
 125         asm volatile(
 126                 "       .insn   rre,0xb22f0000,%1,%2\n"  /* pgout %1,%2 */
 127                 "0:     ipm     %0\n"
 128                 "       srl     %0,28\n"
 129                 "1:\n"
 130                 EX_TABLE(0b,1b)
 131                 : "+d" (cc) : "a" (__pa(page_addr)), "d" (xpage_index) : "cc");
 132         if (cc == 3)
 133                 return -ENXIO;
 134         if (cc == 2)
 135                 return -ENXIO;
 136         if (cc == 1)
 137                 return -EIO;
 138         return 0;
 139 }
 140
 141 /*
 142  * Check if xpram is available.
 143  */
 144 static int xpram_present(void)
 145 {
 146         unsigned long mem_page;
 147         int rc;
 148
 149         mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
 150         if (!mem_page)
 151                 return -ENOMEM;
 152         rc = xpram_page_in(mem_page, 0);
 153         free_page(mem_page);
 154         return rc ? -ENXIO : 0;
 155 }
 156
 157 /*
 158  * Return index of the last available xpram page.
 159  */
 160 static unsigned long xpram_highest_page_index(void)
 161 {
 162         unsigned int page_index, add_bit;
 163         unsigned long mem_page;
 164
 165         mem_page = (unsigned long) __get_free_page(GFP_KERNEL);
 166         if (!mem_page)
 167                 return 0;
 168
 169         page_index = 0;
 170         add_bit = 1ULL << (sizeof(unsigned int)*8 - 1);
 171         while (add_bit > 0) {
 172                 if (xpram_page_in(mem_page, page_index | add_bit) == 0)
 173                         page_index |= add_bit;
 174                 add_bit >>= 1;
 175         }
 176
 177         free_page (mem_page);
 178
 179         return page_index;
 180 }
 181
 182 /*
 183  * Block device make request function.
 184  */
 185 static blk_qc_t xpram_make_request(struct request_queue *q, struct bio *bio)
 186 {
 187         xpram_device_t *xdev = bio->bi_disk->private_data;
 188         struct bio_vec bvec;
 189         struct bvec_iter iter;
 190         unsigned int index;
 191         unsigned long page_addr;
 192         unsigned long bytes;
 193
 194         blk_queue_split(q, &bio);
 195
 196         if ((bio->bi_iter.bi_sector & 7) != 0 ||
 197             (bio->bi_iter.bi_size & 4095) != 0)
 198                 /* Request is not page-aligned. */
 199                 goto fail;
 200         if ((bio->bi_iter.bi_size >> 12) > xdev->size)
 201                 /* Request size is no page-aligned. */
 202                 goto fail;
 203         if ((bio->bi_iter.bi_sector >> 3) > 0xffffffffU - xdev->offset)
 204                 goto fail;
 205         index = (bio->bi_iter.bi_sector >> 3) + xdev->offset;
 206         bio_for_each_segment(bvec, bio, iter) {
 207                 page_addr = (unsigned long)
 208                         kmap(bvec.bv_page) + bvec.bv_offset;
 209                 bytes = bvec.bv_len;
 210                 if ((page_addr & 4095) != 0 || (bytes & 4095) != 0)
 211                         /* More paranoia. */
 212                         goto fail;
 213                 while (bytes > 0) {
 214                         if (bio_data_dir(bio) == READ) {
 215                                 if (xpram_page_in(page_addr, index) != 0)
 216                                         goto fail;
 217                         } else {
 218                                 if (xpram_page_out(page_addr, index) != 0)
 219                                         goto fail;
 220                         }
 221                         page_addr += 4096;
 222                         bytes -= 4096;
 223                         index++;
 224                 }
 225         }
 226         bio_endio(bio);
 227         return BLK_QC_T_NONE;
 228 fail:
 229         bio_io_error(bio);
 230         return BLK_QC_T_NONE;
 231 }
 232
 233 static int xpram_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 234 {
 235         unsigned long size;
 236
 237         /*
 238          * get geometry: we have to fake one...  trim the size to a
 239          * multiple of 64 (32k): tell we have 16 sectors, 4 heads,
 240          * whatever cylinders. Tell also that data starts at sector. 4.
 241          */
 242         size = (xpram_pages * 8) & ~0x3f;
 243         geo->cylinders = size >> 6;
 244         geo->heads = 4;
 245         geo->sectors = 16;
 246         geo->start = 4;
 247         return 0;
 248 }
 249
 250 static const struct block_device_operations xpram_devops =
 251 {
 252         .owner  = THIS_MODULE,
 253         .getgeo = xpram_getgeo,
 254 };
 255
 256 /*
 257  * Setup xpram_sizes array.
 258  */
 259 static int __init xpram_setup_sizes(unsigned long pages)
 260 {
 261         unsigned long mem_needed;
 262         unsigned long mem_auto;
 263         unsigned long long size;
 264         char *sizes_end;
 265         int mem_auto_no;
 266         int i;
 267
 268         /* Check number of devices. */
 269         if (devs <= 0 || devs > XPRAM_MAX_DEVS) {
 270                 pr_err("%d is not a valid number of XPRAM devices\n",devs);
 271                 return -EINVAL;
 272         }
 273         xpram_devs = devs;
 274
 275         /*
 276          * Copy sizes array to xpram_sizes and align partition
 277          * sizes to page boundary.
 278          */
 279         mem_needed = 0;
 280         mem_auto_no = 0;
 281         for (i = 0; i < xpram_devs; i++) {
 282                 if (sizes[i]) {
 283                         size = simple_strtoull(sizes[i], &sizes_end, 0);
 284                         switch (*sizes_end) {
 285                         case 'g':
 286                         case 'G':
 287                                 size <<= 20;
 288                                 break;
 289                         case 'm':
 290                         case 'M':
 291                                 size <<= 10;
 292                         }
 293                         xpram_sizes[i] = (size + 3) & -4UL;
 294                 }
 295                 if (xpram_sizes[i])
 296                         mem_needed += xpram_sizes[i];
 297                 else
 298                         mem_auto_no++;
 299         }
 300
 301         pr_info("  number of devices (partitions): %d \n", xpram_devs);
 302         for (i = 0; i < xpram_devs; i++) {
 303                 if (xpram_sizes[i])
 304                         pr_info("  size of partition %d: %u kB\n",
 305                                 i, xpram_sizes[i]);
 306                 else
 307                         pr_info("  size of partition %d to be set "
 308                                 "automatically\n",i);
 309         }
 310         pr_info("  memory needed (for sized partitions): %lu kB\n",
 311                 mem_needed);
 312         pr_info("  partitions to be sized automatically: %d\n",
 313                 mem_auto_no);
 314
 315         if (mem_needed > pages * 4) {
 316                 pr_err("Not enough expanded memory available\n");
 317                 return -EINVAL;
 318         }
 319
 320         /*
 321          * partitioning:
 322          * xpram_sizes[i] != 0; partition i has size xpram_sizes[i] kB
 323          * else:             ; all partitions with zero xpram_sizes[i]
 324          *                     partition equally the remaining space
 325          */
 326         if (mem_auto_no) {
 327                 mem_auto = ((pages - mem_needed / 4) / mem_auto_no) * 4;
 328                 pr_info("  automatically determined "
 329                         "partition size: %lu kB\n", mem_auto);
 330                 for (i = 0; i < xpram_devs; i++)
 331                         if (xpram_sizes[i] == 0)
 332                                 xpram_sizes[i] = mem_auto;
 333         }
 334         return 0;
 335 }
 336
 337 static int __init xpram_setup_blkdev(void)
 338 {
 339         unsigned long offset;
 340         int i, rc = -ENOMEM;
 341
 342         for (i = 0; i < xpram_devs; i++) {
 343                 xpram_disks[i] = alloc_disk(1);
 344                 if (!xpram_disks[i])
 345                         goto out;
 346                 xpram_queues[i] = blk_alloc_queue(GFP_KERNEL);
 347                 if (!xpram_queues[i]) {
 348                         put_disk(xpram_disks[i]);
 349                         goto out;
 350                 }
 351                 blk_queue_flag_set(QUEUE_FLAG_NONROT, xpram_queues[i]);
 352                 blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, xpram_queues[i]);
 353                 blk_queue_make_request(xpram_queues[i], xpram_make_request);
 354                 blk_queue_logical_block_size(xpram_queues[i], 4096);
 355         }
 356
 357         /*
 358          * Register xpram major.
 359          */
 360         rc = register_blkdev(XPRAM_MAJOR, XPRAM_NAME);
 361         if (rc < 0)
 362                 goto out;
 363
 364         /*
 365          * Setup device structures.
 366          */
 367         offset = 0;
 368         for (i = 0; i < xpram_devs; i++) {
 369                 struct gendisk *disk = xpram_disks[i];
 370
 371                 xpram_devices[i].size = xpram_sizes[i] / 4;
 372                 xpram_devices[i].offset = offset;
 373                 offset += xpram_devices[i].size;
 374                 disk->major = XPRAM_MAJOR;
 375                 disk->first_minor = i;
 376                 disk->fops = &xpram_devops;
 377                 disk->private_data = &xpram_devices[i];
 378                 disk->queue = xpram_queues[i];
 379                 sprintf(disk->disk_name, "slram%d", i);
 380                 set_capacity(disk, xpram_sizes[i] << 1);
 381                 add_disk(disk);
 382         }
 383
 384         return 0;
 385 out:
 386         while (i--) {
 387                 blk_cleanup_queue(xpram_queues[i]);
 388                 put_disk(xpram_disks[i]);
 389         }
 390         return rc;
 391 }
 392
 393 /*
 394  * Resume failed: Print error message and call panic.
 395  */
 396 static void xpram_resume_error(const char *message)
 397 {
 398         pr_err("Resuming the system failed: %s\n", message);
 399         panic("xpram resume error\n");
 400 }
 401
 402 /*
 403  * Check if xpram setup changed between suspend and resume.
 404  */
 405 static int xpram_restore(struct device *dev)
 406 {
 407         if (!xpram_pages)
 408                 return 0;
 409         if (xpram_present() != 0)
 410                 xpram_resume_error("xpram disappeared");
 411         if (xpram_pages != xpram_highest_page_index() + 1)
 412                 xpram_resume_error("Size of xpram changed");
 413         return 0;
 414 }
 415
 416 static const struct dev_pm_ops xpram_pm_ops = {
 417         .restore        = xpram_restore,
 418 };
 419
 420 static struct platform_driver xpram_pdrv = {
 421         .driver = {
 422                 .name   = XPRAM_NAME,
 423                 .pm     = &xpram_pm_ops,
 424         },
 425 };
 426
 427 static struct platform_device *xpram_pdev;
 428
 429 /*
 430  * Finally, the init/exit functions.
 431  */
 432 static void __exit xpram_exit(void)
 433 {
 434         int i;
 435         for (i = 0; i < xpram_devs; i++) {
 436                 del_gendisk(xpram_disks[i]);
 437                 blk_cleanup_queue(xpram_queues[i]);
 438                 put_disk(xpram_disks[i]);
 439         }
 440         unregister_blkdev(XPRAM_MAJOR, XPRAM_NAME);
 441         platform_device_unregister(xpram_pdev);
 442         platform_driver_unregister(&xpram_pdrv);
 443 }
 444
 445 static int __init xpram_init(void)
 446 {
 447         int rc;
 448
 449         /* Find out size of expanded memory. */
 450         if (xpram_present() != 0) {
 451                 pr_err("No expanded memory available\n");
 452                 return -ENODEV;
 453         }
 454         xpram_pages = xpram_highest_page_index() + 1;
 455         pr_info("  %u pages expanded memory found (%lu KB).\n",
 456                 xpram_pages, (unsigned long) xpram_pages*4);
 457         rc = xpram_setup_sizes(xpram_pages);
 458         if (rc)
 459                 return rc;
 460         rc = platform_driver_register(&xpram_pdrv);
 461         if (rc)
 462                 return rc;
 463         xpram_pdev = platform_device_register_simple(XPRAM_NAME, -1, NULL, 0);
 464         if (IS_ERR(xpram_pdev)) {
 465                 rc = PTR_ERR(xpram_pdev);
 466                 goto fail_platform_driver_unregister;
 467         }
 468         rc = xpram_setup_blkdev();
 469         if (rc)
 470                 goto fail_platform_device_unregister;
 471         return 0;
 472
 473 fail_platform_device_unregister:
 474         platform_device_unregister(xpram_pdev);
 475 fail_platform_driver_unregister:
 476         platform_driver_unregister(&xpram_pdrv);
 477         return rc;
 478 }
 479
 480 module_init(xpram_init);
 481 module_exit(xpram_exit);