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