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