fs/devfs/util.c

   1 /*  devfs (Device FileSystem) utilities.
   2
   3     Copyright (C) 1999-2002  Richard Gooch
   4
   5     This library is free software; you can redistribute it and/or
   6     modify it under the terms of the GNU Library General Public
   7     License as published by the Free Software Foundation; either
   8     version 2 of the License, or (at your option) any later version.
   9
  10     This library is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13     Library General Public License for more details.
  14
  15     You should have received a copy of the GNU Library General Public
  16     License along with this library; if not, write to the Free
  17     Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18
  19     Richard Gooch may be reached by email at  rgooch@atnf.csiro.au
  20     The postal address is:
  21       Richard Gooch, c/o ATNF, P. O. Box 76, Epping, N.S.W., 2121, Australia.
  22
  23     ChangeLog
  24
  25     19991031   Richard Gooch <rgooch@atnf.csiro.au>
  26                Created.
  27     19991103   Richard Gooch <rgooch@atnf.csiro.au>
  28                Created <_devfs_convert_name> and supported SCSI and IDE CD-ROMs
  29     20000203   Richard Gooch <rgooch@atnf.csiro.au>
  30                Changed operations pointer type to void *.
  31     20000621   Richard Gooch <rgooch@atnf.csiro.au>
  32                Changed interface to <devfs_register_series>.
  33     20000622   Richard Gooch <rgooch@atnf.csiro.au>
  34                Took account of interface change to <devfs_mk_symlink>.
  35                Took account of interface change to <devfs_mk_dir>.
  36     20010519   Richard Gooch <rgooch@atnf.csiro.au>
  37                Documentation cleanup.
  38     20010709   Richard Gooch <rgooch@atnf.csiro.au>
  39                Created <devfs_*alloc_major> and <devfs_*alloc_devnum>.
  40     20010710   Richard Gooch <rgooch@atnf.csiro.au>
  41                Created <devfs_*alloc_unique_number>.
  42     20010730   Richard Gooch <rgooch@atnf.csiro.au>
  43                Documentation typo fix.
  44     20010806   Richard Gooch <rgooch@atnf.csiro.au>
  45                Made <block_semaphore> and <char_semaphore> private.
  46     20010813   Richard Gooch <rgooch@atnf.csiro.au>
  47                Fixed bug in <devfs_alloc_unique_number>: limited to 128 numbers
  48     20010818   Richard Gooch <rgooch@atnf.csiro.au>
  49                Updated major masks up to Linus' "no new majors" proclamation.
  50                Block: were 126 now 122 free, char: were 26 now 19 free.
  51     20020324   Richard Gooch <rgooch@atnf.csiro.au>
  52                Fixed bug in <devfs_alloc_unique_number>: was clearing beyond
  53                bitfield.
  54     20020326   Richard Gooch <rgooch@atnf.csiro.au>
  55                Fixed bitfield data type for <devfs_*alloc_devnum>.
  56                Made major bitfield type and initialiser 64 bit safe.
  57     20020413   Richard Gooch <rgooch@atnf.csiro.au>
  58                Fixed shift warning on 64 bit machines.
  59     20020428   Richard Gooch <rgooch@atnf.csiro.au>
  60                Copied and used macro for error messages from fs/devfs/base.c
  61     20021013   Richard Gooch <rgooch@atnf.csiro.au>
  62                Documentation fix.
  63     20030101   Adam J. Richter <adam@yggdrasil.com>
  64                Eliminate DEVFS_SPECIAL_{CHR,BLK}.  Use mode_t instead.
  65     20030106   Christoph Hellwig <hch@infradead.org>
  66                Rewrite devfs_{,de}alloc_devnum to look like C code.
  67 */
  68 #include <linux/module.h>
  69 #include <linux/init.h>
  70 #include <linux/devfs_fs_kernel.h>
  71 #include <linux/slab.h>
  72 #include <linux/vmalloc.h>
  73 #include <linux/genhd.h>
  74 #include <linux/bitops.h>
  75
  76 int devfs_register_tape(const char *name)
  77 {
  78         char tname[32], dest[64];
  79         static unsigned int tape_counter;
  80         unsigned int n = tape_counter++;
  81
  82         sprintf(dest, "../%s", name);
  83         sprintf(tname, "tapes/tape%u", n);
  84         devfs_mk_symlink(tname, dest);
  85
  86         return n;
  87 }
  88
  89 EXPORT_SYMBOL(devfs_register_tape);
  90
  91 void devfs_unregister_tape(int num)
  92 {
  93         if (num >= 0)
  94                 devfs_remove("tapes/tape%u", num);
  95 }
  96
  97 EXPORT_SYMBOL(devfs_unregister_tape);