drivers/char/mem.c

   1 /*
   2  *  linux/drivers/char/mem.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *
   6  *  Added devfs support.
   7  *    Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
   8  *  Shared /dev/zero mmaping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
   9  */
  10
  11 #include <linux/config.h>
  12 #include <linux/mm.h>
  13 #include <linux/miscdevice.h>
  14 #include <linux/slab.h>
  15 #include <linux/vmalloc.h>
  16 #include <linux/mman.h>
  17 #include <linux/random.h>
  18 #include <linux/init.h>
  19 #include <linux/raw.h>
  20 #include <linux/tty.h>
  21 #include <linux/capability.h>
  22 #include <linux/smp_lock.h>
  23 #include <linux/devfs_fs_kernel.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/device.h>
  26
  27 #include <asm/uaccess.h>
  28 #include <asm/io.h>
  29 #include <asm/pgalloc.h>
  30
  31 #ifdef CONFIG_IA64
  32 # include <linux/efi.h>
  33 #endif
  34
  35 #ifdef CONFIG_FB
  36 extern void fbmem_init(void);
  37 #endif
  38 #if defined(CONFIG_S390_TAPE) && defined(CONFIG_S390_TAPE_CHAR)
  39 extern void tapechar_init(void);
  40 #endif
  41
  42 /*
  43  * Architectures vary in how they handle caching for addresses
  44  * outside of main memory.
  45  *
  46  */
  47 static inline int uncached_access(struct file *file, unsigned long addr)
  48 {
  49 #if defined(__i386__)
  50         /*
  51          * On the PPro and successors, the MTRRs are used to set
  52          * memory types for physical addresses outside main memory,
  53          * so blindly setting PCD or PWT on those pages is wrong.
  54          * For Pentiums and earlier, the surround logic should disable
  55          * caching for the high addresses through the KEN pin, but
  56          * we maintain the tradition of paranoia in this code.
  57          */
  58         if (file->f_flags & O_SYNC)
  59                 return 1;
  60         return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
  61                   test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
  62                   test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
  63                   test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
  64           && addr >= __pa(high_memory);
  65 #elif defined(__x86_64__)
  66         /*
  67          * This is broken because it can generate memory type aliases,
  68          * which can cause cache corruptions
  69          * But it is only available for root and we have to be bug-to-bug
  70          * compatible with i386.
  71          */
  72         if (file->f_flags & O_SYNC)
  73                 return 1;
  74         /* same behaviour as i386. PAT always set to cached and MTRRs control the
  75            caching behaviour.
  76            Hopefully a full PAT implementation will fix that soon. */
  77         return 0;
  78 #elif defined(CONFIG_IA64)
  79         /*
  80          * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
  81          */
  82         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
  83 #elif defined(CONFIG_PPC64)
  84         /* On PPC64, we always do non-cacheable access to the IO hole and
  85          * cacheable elsewhere. Cache paradox can checkstop the CPU and
  86          * the high_memory heuristic below is wrong on machines with memory
  87          * above the IO hole... Ah, and of course, XFree86 doesn't pass
  88          * O_SYNC when mapping us to tap IO space. Surprised ?
  89          */
  90         return !page_is_ram(addr);
  91 #else
  92         /*
  93          * Accessing memory above the top the kernel knows about or through a file pointer
  94          * that was marked O_SYNC will be done non-cached.
  95          */
  96         if (file->f_flags & O_SYNC)
  97                 return 1;
  98         return addr >= __pa(high_memory);
  99 #endif
 100 }
 101
 102 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
 103 static inline int valid_phys_addr_range(unsigned long addr, size_t *count)
 104 {
 105         unsigned long end_mem;
 106
 107         end_mem = __pa(high_memory);
 108         if (addr >= end_mem)
 109                 return 0;
 110
 111         if (*count > end_mem - addr)
 112                 *count = end_mem - addr;
 113
 114         return 1;
 115 }
 116 #endif
 117
 118 static ssize_t do_write_mem(void *p, unsigned long realp,
 119                             const char __user * buf, size_t count, loff_t *ppos)
 120 {
 121         ssize_t written;
 122         unsigned long copied;
 123
 124         written = 0;
 125 #if defined(__sparc__) || (defined(__mc68000__) && defined(CONFIG_MMU))
 126         /* we don't have page 0 mapped on sparc and m68k.. */
 127         if (realp < PAGE_SIZE) {
 128                 unsigned long sz = PAGE_SIZE-realp;
 129                 if (sz > count) sz = count;
 130                 /* Hmm. Do something? */
 131                 buf+=sz;
 132                 p+=sz;
 133                 count-=sz;
 134                 written+=sz;
 135         }
 136 #endif
 137         copied = copy_from_user(p, buf, count);
 138         if (copied) {
 139                 ssize_t ret = written + (count - copied);
 140
 141                 if (ret)
 142                         return ret;
 143                 return -EFAULT;
 144         }
 145         written += count;
 146         *ppos += written;
 147         return written;
 148 }
 149
 150
 151 /*
 152  * This funcion reads the *physical* memory. The f_pos points directly to the
 153  * memory location.
 154  */
 155 static ssize_t read_mem(struct file * file, char __user * buf,
 156                         size_t count, loff_t *ppos)
 157 {
 158         unsigned long p = *ppos;
 159         ssize_t read;
 160
 161         if (!valid_phys_addr_range(p, &count))
 162                 return -EFAULT;
 163         read = 0;
 164 #if defined(__sparc__) || (defined(__mc68000__) && defined(CONFIG_MMU))
 165         /* we don't have page 0 mapped on sparc and m68k.. */
 166         if (p < PAGE_SIZE) {
 167                 unsigned long sz = PAGE_SIZE-p;
 168                 if (sz > count)
 169                         sz = count;
 170                 if (sz > 0) {
 171                         if (clear_user(buf, sz))
 172                                 return -EFAULT;
 173                         buf += sz;
 174                         p += sz;
 175                         count -= sz;
 176                         read += sz;
 177                 }
 178         }
 179 #endif
 180         if (copy_to_user(buf, __va(p), count))
 181                 return -EFAULT;
 182         read += count;
 183         *ppos += read;
 184         return read;
 185 }
 186
 187 static ssize_t write_mem(struct file * file, const char __user * buf,
 188                          size_t count, loff_t *ppos)
 189 {
 190         unsigned long p = *ppos;
 191
 192         if (!valid_phys_addr_range(p, &count))
 193                 return -EFAULT;
 194         return do_write_mem(__va(p), p, buf, count, ppos);
 195 }
 196
 197 static int mmap_mem(struct file * file, struct vm_area_struct * vma)
 198 {
 199         unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
 200         int uncached;
 201
 202         uncached = uncached_access(file, offset);
 203 #ifdef pgprot_noncached
 204         if (uncached)
 205                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 206 #endif
 207
 208         /* Don't try to swap out physical pages.. */
 209         vma->vm_flags |= VM_RESERVED;
 210
 211         /*
 212          * Don't dump addresses that are not real memory to a core file.
 213          */
 214         if (uncached)
 215                 vma->vm_flags |= VM_IO;
 216
 217         if (remap_page_range(vma, vma->vm_start, offset, vma->vm_end-vma->vm_start,
 218                              vma->vm_page_prot))
 219                 return -EAGAIN;
 220         return 0;
 221 }
 222
 223 extern long vread(char *buf, char *addr, unsigned long count);
 224 extern long vwrite(char *buf, char *addr, unsigned long count);
 225
 226 /*
 227  * This function reads the *virtual* memory as seen by the kernel.
 228  */
 229 static ssize_t read_kmem(struct file *file, char __user *buf,
 230                          size_t count, loff_t *ppos)
 231 {
 232         unsigned long p = *ppos;
 233         ssize_t read = 0;
 234         ssize_t virtr = 0;
 235         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
 236
 237         if (p < (unsigned long) high_memory) {
 238                 read = count;
 239                 if (count > (unsigned long) high_memory - p)
 240                         read = (unsigned long) high_memory - p;
 241
 242 #if defined(__sparc__) || (defined(__mc68000__) && defined(CONFIG_MMU))
 243                 /* we don't have page 0 mapped on sparc and m68k.. */
 244                 if (p < PAGE_SIZE && read > 0) {
 245                         size_t tmp = PAGE_SIZE - p;
 246                         if (tmp > read) tmp = read;
 247                         if (clear_user(buf, tmp))
 248                                 return -EFAULT;
 249                         buf += tmp;
 250                         p += tmp;
 251                         read -= tmp;
 252                         count -= tmp;
 253                 }
 254 #endif
 255                 if (copy_to_user(buf, (char *)p, read))
 256                         return -EFAULT;
 257                 p += read;
 258                 buf += read;
 259                 count -= read;
 260         }
 261
 262         if (count > 0) {
 263                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 264                 if (!kbuf)
 265                         return -ENOMEM;
 266                 while (count > 0) {
 267                         int len = count;
 268
 269                         if (len > PAGE_SIZE)
 270                                 len = PAGE_SIZE;
 271                         len = vread(kbuf, (char *)p, len);
 272                         if (!len)
 273                                 break;
 274                         if (copy_to_user(buf, kbuf, len)) {
 275                                 free_page((unsigned long)kbuf);
 276                                 return -EFAULT;
 277                         }
 278                         count -= len;
 279                         buf += len;
 280                         virtr += len;
 281                         p += len;
 282                 }
 283                 free_page((unsigned long)kbuf);
 284         }
 285         *ppos = p;
 286         return virtr + read;
 287 }
 288
 289 /*
 290  * This function writes to the *virtual* memory as seen by the kernel.
 291  */
 292 static ssize_t write_kmem(struct file * file, const char __user * buf,
 293                           size_t count, loff_t *ppos)
 294 {
 295         unsigned long p = *ppos;
 296         ssize_t wrote = 0;
 297         ssize_t virtr = 0;
 298         ssize_t written;
 299         char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
 300
 301         if (p < (unsigned long) high_memory) {
 302
 303                 wrote = count;
 304                 if (count > (unsigned long) high_memory - p)
 305                         wrote = (unsigned long) high_memory - p;
 306
 307                 written = do_write_mem((void*)p, p, buf, wrote, ppos);
 308                 if (written != wrote)
 309                         return written;
 310                 wrote = written;
 311                 p += wrote;
 312                 buf += wrote;
 313                 count -= wrote;
 314         }
 315
 316         if (count > 0) {
 317                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 318                 if (!kbuf)
 319                         return wrote ? wrote : -ENOMEM;
 320                 while (count > 0) {
 321                         int len = count;
 322
 323                         if (len > PAGE_SIZE)
 324                                 len = PAGE_SIZE;
 325                         if (len) {
 326                                 written = copy_from_user(kbuf, buf, len);
 327                                 if (written) {
 328                                         ssize_t ret;
 329
 330                                         free_page((unsigned long)kbuf);
 331                                         ret = wrote + virtr + (len - written);
 332                                         return ret ? ret : -EFAULT;
 333                                 }
 334                         }
 335                         len = vwrite(kbuf, (char *)p, len);
 336                         count -= len;
 337                         buf += len;
 338                         virtr += len;
 339                         p += len;
 340                 }
 341                 free_page((unsigned long)kbuf);
 342         }
 343
 344         *ppos = p;
 345         return virtr + wrote;
 346 }
 347
 348 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 349 static ssize_t read_port(struct file * file, char __user * buf,
 350                          size_t count, loff_t *ppos)
 351 {
 352         unsigned long i = *ppos;
 353         char __user *tmp = buf;
 354
 355         if (verify_area(VERIFY_WRITE,buf,count))
 356                 return -EFAULT;
 357         while (count-- > 0 && i < 65536) {
 358                 if (__put_user(inb(i),tmp) < 0)
 359                         return -EFAULT;
 360                 i++;
 361                 tmp++;
 362         }
 363         *ppos = i;
 364         return tmp-buf;
 365 }
 366
 367 static ssize_t write_port(struct file * file, const char __user * buf,
 368                           size_t count, loff_t *ppos)
 369 {
 370         unsigned long i = *ppos;
 371         const char __user * tmp = buf;
 372
 373         if (verify_area(VERIFY_READ,buf,count))
 374                 return -EFAULT;
 375         while (count-- > 0 && i < 65536) {
 376                 char c;
 377                 if (__get_user(c, tmp))
 378                         return -EFAULT;
 379                 outb(c,i);
 380                 i++;
 381                 tmp++;
 382         }
 383         *ppos = i;
 384         return tmp-buf;
 385 }
 386 #endif
 387
 388 static ssize_t read_null(struct file * file, char __user * buf,
 389                          size_t count, loff_t *ppos)
 390 {
 391         return 0;
 392 }
 393
 394 static ssize_t write_null(struct file * file, const char __user * buf,
 395                           size_t count, loff_t *ppos)
 396 {
 397         return count;
 398 }
 399
 400 #ifdef CONFIG_MMU
 401 /*
 402  * For fun, we are using the MMU for this.
 403  */
 404 static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
 405 {
 406         struct mm_struct *mm;
 407         struct vm_area_struct * vma;
 408         unsigned long addr=(unsigned long)buf;
 409
 410         mm = current->mm;
 411         /* Oops, this was forgotten before. -ben */
 412         down_read(&mm->mmap_sem);
 413
 414         /* For private mappings, just map in zero pages. */
 415         for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
 416                 unsigned long count;
 417
 418                 if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
 419                         goto out_up;
 420                 if (vma->vm_flags & VM_SHARED)
 421                         break;
 422                 count = vma->vm_end - addr;
 423                 if (count > size)
 424                         count = size;
 425
 426                 zap_page_range(vma, addr, count, NULL);
 427                 zeromap_page_range(vma, addr, count, PAGE_COPY);
 428
 429                 size -= count;
 430                 buf += count;
 431                 addr += count;
 432                 if (size == 0)
 433                         goto out_up;
 434         }
 435
 436         up_read(&mm->mmap_sem);
 437
 438         /* The shared case is hard. Let's do the conventional zeroing. */
 439         do {
 440                 unsigned long unwritten = clear_user(buf, PAGE_SIZE);
 441                 if (unwritten)
 442                         return size + unwritten - PAGE_SIZE;
 443                 cond_resched();
 444                 buf += PAGE_SIZE;
 445                 size -= PAGE_SIZE;
 446         } while (size);
 447
 448         return size;
 449 out_up:
 450         up_read(&mm->mmap_sem);
 451         return size;
 452 }
 453
 454 static ssize_t read_zero(struct file * file, char __user * buf,
 455                          size_t count, loff_t *ppos)
 456 {
 457         unsigned long left, unwritten, written = 0;
 458
 459         if (!count)
 460                 return 0;
 461
 462         if (!access_ok(VERIFY_WRITE, buf, count))
 463                 return -EFAULT;
 464
 465         left = count;
 466
 467         /* do we want to be clever? Arbitrary cut-off */
 468         if (count >= PAGE_SIZE*4) {
 469                 unsigned long partial;
 470
 471                 /* How much left of the page? */
 472                 partial = (PAGE_SIZE-1) & -(unsigned long) buf;
 473                 unwritten = clear_user(buf, partial);
 474                 written = partial - unwritten;
 475                 if (unwritten)
 476                         goto out;
 477                 left -= partial;
 478                 buf += partial;
 479                 unwritten = read_zero_pagealigned(buf, left & PAGE_MASK);
 480                 written += (left & PAGE_MASK) - unwritten;
 481                 if (unwritten)
 482                         goto out;
 483                 buf += left & PAGE_MASK;
 484                 left &= ~PAGE_MASK;
 485         }
 486         unwritten = clear_user(buf, left);
 487         written += left - unwritten;
 488 out:
 489         return written ? written : -EFAULT;
 490 }
 491
 492 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
 493 {
 494         if (vma->vm_flags & VM_SHARED)
 495                 return shmem_zero_setup(vma);
 496         if (zeromap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot))
 497                 return -EAGAIN;
 498         return 0;
 499 }
 500 #else /* CONFIG_MMU */
 501 static ssize_t read_zero(struct file * file, char * buf,
 502                          size_t count, loff_t *ppos)
 503 {
 504         size_t todo = count;
 505
 506         while (todo) {
 507                 size_t chunk = todo;
 508
 509                 if (chunk > 4096)
 510                         chunk = 4096;   /* Just for latency reasons */
 511                 if (clear_user(buf, chunk))
 512                         return -EFAULT;
 513                 buf += chunk;
 514                 todo -= chunk;
 515                 cond_resched();
 516         }
 517         return count;
 518 }
 519
 520 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
 521 {
 522         return -ENOSYS;
 523 }
 524 #endif /* CONFIG_MMU */
 525
 526 static ssize_t write_full(struct file * file, const char __user * buf,
 527                           size_t count, loff_t *ppos)
 528 {
 529         return -ENOSPC;
 530 }
 531
 532 /*
 533  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
 534  * can fopen() both devices with "a" now.  This was previously impossible.
 535  * -- SRB.
 536  */
 537
 538 static loff_t null_lseek(struct file * file, loff_t offset, int orig)
 539 {
 540         return file->f_pos = 0;
 541 }
 542
 543 /*
 544  * The memory devices use the full 32/64 bits of the offset, and so we cannot
 545  * check against negative addresses: they are ok. The return value is weird,
 546  * though, in that case (0).
 547  *
 548  * also note that seeking relative to the "end of file" isn't supported:
 549  * it has no meaning, so it returns -EINVAL.
 550  */
 551 static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
 552 {
 553         loff_t ret;
 554
 555         down(&file->f_dentry->d_inode->i_sem);
 556         switch (orig) {
 557                 case 0:
 558                         file->f_pos = offset;
 559                         ret = file->f_pos;
 560                         force_successful_syscall_return();
 561                         break;
 562                 case 1:
 563                         file->f_pos += offset;
 564                         ret = file->f_pos;
 565                         force_successful_syscall_return();
 566                         break;
 567                 default:
 568                         ret = -EINVAL;
 569         }
 570         up(&file->f_dentry->d_inode->i_sem);
 571         return ret;
 572 }
 573
 574 static int open_port(struct inode * inode, struct file * filp)
 575 {
 576         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
 577 }
 578
 579 #define mmap_kmem       mmap_mem
 580 #define zero_lseek      null_lseek
 581 #define full_lseek      null_lseek
 582 #define write_zero      write_null
 583 #define read_full       read_zero
 584 #define open_mem        open_port
 585 #define open_kmem       open_mem
 586
 587 static struct file_operations mem_fops = {
 588         .llseek         = memory_lseek,
 589         .read           = read_mem,
 590         .write          = write_mem,
 591         .mmap           = mmap_mem,
 592         .open           = open_mem,
 593 };
 594
 595 static struct file_operations kmem_fops = {
 596         .llseek         = memory_lseek,
 597         .read           = read_kmem,
 598         .write          = write_kmem,
 599         .mmap           = mmap_kmem,
 600         .open           = open_kmem,
 601 };
 602
 603 static struct file_operations null_fops = {
 604         .llseek         = null_lseek,
 605         .read           = read_null,
 606         .write          = write_null,
 607 };
 608
 609 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 610 static struct file_operations port_fops = {
 611         .llseek         = memory_lseek,
 612         .read           = read_port,
 613         .write          = write_port,
 614         .open           = open_port,
 615 };
 616 #endif
 617
 618 static struct file_operations zero_fops = {
 619         .llseek         = zero_lseek,
 620         .read           = read_zero,
 621         .write          = write_zero,
 622         .mmap           = mmap_zero,
 623 };
 624
 625 static struct file_operations full_fops = {
 626         .llseek         = full_lseek,
 627         .read           = read_full,
 628         .write          = write_full,
 629 };
 630
 631 static ssize_t kmsg_write(struct file * file, const char __user * buf,
 632                           size_t count, loff_t *ppos)
 633 {
 634         char *tmp;
 635         int ret;
 636
 637         tmp = kmalloc(count + 1, GFP_KERNEL);
 638         if (tmp == NULL)
 639                 return -ENOMEM;
 640         ret = -EFAULT;
 641         if (!copy_from_user(tmp, buf, count)) {
 642                 tmp[count] = 0;
 643                 ret = printk("%s", tmp);
 644         }
 645         kfree(tmp);
 646         return ret;
 647 }
 648
 649 static struct file_operations kmsg_fops = {
 650         .write =        kmsg_write,
 651 };
 652
 653 static int memory_open(struct inode * inode, struct file * filp)
 654 {
 655         switch (iminor(inode)) {
 656                 case 1:
 657                         filp->f_op = &mem_fops;
 658                         break;
 659                 case 2:
 660                         filp->f_op = &kmem_fops;
 661                         break;
 662                 case 3:
 663                         filp->f_op = &null_fops;
 664                         break;
 665 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 666                 case 4:
 667                         filp->f_op = &port_fops;
 668                         break;
 669 #endif
 670                 case 5:
 671                         filp->f_op = &zero_fops;
 672                         break;
 673                 case 7:
 674                         filp->f_op = &full_fops;
 675                         break;
 676                 case 8:
 677                         filp->f_op = &random_fops;
 678                         break;
 679                 case 9:
 680                         filp->f_op = &urandom_fops;
 681                         break;
 682                 case 11:
 683                         filp->f_op = &kmsg_fops;
 684                         break;
 685                 default:
 686                         return -ENXIO;
 687         }
 688         if (filp->f_op && filp->f_op->open)
 689                 return filp->f_op->open(inode,filp);
 690         return 0;
 691 }
 692
 693 static struct file_operations memory_fops = {
 694         .open           = memory_open,  /* just a selector for the real open */
 695 };
 696
 697 static const struct {
 698         unsigned int            minor;
 699         char                    *name;
 700         umode_t                 mode;
 701         struct file_operations  *fops;
 702 } devlist[] = { /* list of minor devices */
 703         {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
 704         {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
 705         {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
 706 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 707         {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
 708 #endif
 709         {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops},
 710         {7, "full",    S_IRUGO | S_IWUGO,           &full_fops},
 711         {8, "random",  S_IRUGO | S_IWUSR,           &random_fops},
 712         {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops},
 713         {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops},
 714 };
 715
 716 static struct class_simple *mem_class;
 717
 718 static int __init chr_dev_init(void)
 719 {
 720         int i;
 721
 722         if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
 723                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 724
 725         mem_class = class_simple_create(THIS_MODULE, "mem");
 726         for (i = 0; i < ARRAY_SIZE(devlist); i++) {
 727                 class_simple_device_add(mem_class,
 728                                         MKDEV(MEM_MAJOR, devlist[i].minor),
 729                                         NULL, devlist[i].name);
 730                 devfs_mk_cdev(MKDEV(MEM_MAJOR, devlist[i].minor),
 731                                 S_IFCHR | devlist[i].mode, devlist[i].name);
 732         }
 733
 734 #if defined (CONFIG_FB)
 735         fbmem_init();
 736 #endif
 737         return 0;
 738 }
 739
 740 fs_initcall(chr_dev_init);