sysdeps/unix/sysv/linux/arm/ioperm.c

   1 /* Copyright (C) 1998-2017 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Phil Blundell, based on the Alpha version by
   4    David Mosberger.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library.  If not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 /* I/O port access on the ARM is something of a fiction.  What we do is to
  21    map an appropriate area of /dev/mem into user space so that a program
  22    can blast away at the hardware in such a way as to generate I/O cycles
  23    on the bus.  To insulate user code from dependencies on particular
  24    hardware we don't allow calls to inb() and friends to be inlined, but
  25    force them to come through code in here every time.  Performance-critical
  26    registers tend to be memory mapped these days so this should be no big
  27    problem.  */
  28
  29 /* Once upon a time this file used mprotect to enable and disable
  30    access to particular areas of I/O space.  Unfortunately the
  31    mprotect syscall also has the side effect of enabling caching for
  32    the area affected (this is a kernel limitation).  So we now just
  33    enable all the ports all of the time.  */
  34
  35 #include <errno.h>
  36 #include <fcntl.h>
  37 #include <stdio.h>
  38 #include <ctype.h>
  39 #include <stdlib.h>
  40 #include <unistd.h>
  41
  42 #include <sys/types.h>
  43 #include <sys/mman.h>
  44
  45 #include <sys/sysctl.h>
  46
  47 #define MAX_PORT        0x10000
  48
  49 static struct {
  50   unsigned long int     base;
  51   unsigned long int     io_base;
  52   unsigned int          shift;
  53   unsigned int          initdone;       /* since all the above could be 0 */
  54 } io;
  55
  56 #define IO_ADDR(port)   (io.base + ((port) << io.shift))
  57
  58 /*
  59  * Initialize I/O system.  The io_bae and port_shift values are fetched
  60  * using sysctl (CTL_BUS, CTL_BUS_ISA, ISA_*).
  61  */
  62
  63 static int
  64 init_iosys (void)
  65 {
  66   static int iobase_name[] = { CTL_BUS, CTL_BUS_ISA, BUS_ISA_PORT_BASE };
  67   static int ioshift_name[] = { CTL_BUS, CTL_BUS_ISA, BUS_ISA_PORT_SHIFT };
  68   size_t len = sizeof(io.base);
  69
  70   if (! __sysctl (iobase_name, 3, &io.io_base, &len, NULL, 0)
  71       && ! __sysctl (ioshift_name, 3, &io.shift, &len, NULL, 0))
  72     {
  73       io.initdone = 1;
  74       return 0;
  75     }
  76
  77   /* sysctl has failed... */
  78   __set_errno (ENODEV);
  79   return -1;
  80 }
  81
  82 int
  83 _ioperm (unsigned long int from, unsigned long int num, int turn_on)
  84 {
  85   if (! io.initdone && init_iosys () < 0)
  86     return -1;
  87
  88   /* this test isn't as silly as it may look like; consider overflows! */
  89   if (from >= MAX_PORT || from + num > MAX_PORT)
  90     {
  91       __set_errno (EINVAL);
  92       return -1;
  93     }
  94
  95   if (turn_on)
  96     {
  97       if (! io.base)
  98         {
  99           int fd;
 100
 101           fd = __open ("/dev/mem", O_RDWR);
 102           if (fd < 0)
 103             return -1;
 104
 105           io.base =
 106             (unsigned long int) __mmap (0, MAX_PORT << io.shift,
 107                                         PROT_READ | PROT_WRITE,
 108                                         MAP_SHARED, fd, io.io_base);
 109           __close (fd);
 110           if ((long) io.base == -1)
 111             return -1;
 112         }
 113     }
 114
 115   return 0;
 116 }
 117
 118
 119 int
 120 _iopl (unsigned int level)
 121 {
 122     if (level > 3)
 123       {
 124         __set_errno (EINVAL);
 125         return -1;
 126       }
 127     if (level)
 128       {
 129         return _ioperm (0, MAX_PORT, 1);
 130       }
 131     return 0;
 132 }
 133
 134
 135 void
 136 _outb (unsigned char b, unsigned long int port)
 137 {
 138   *((volatile unsigned char *)(IO_ADDR (port))) = b;
 139 }
 140
 141
 142 void
 143 _outw (unsigned short b, unsigned long int port)
 144 {
 145   *((volatile unsigned short *)(IO_ADDR (port))) = b;
 146 }
 147
 148
 149 void
 150 _outl (unsigned int b, unsigned long int port)
 151 {
 152   *((volatile unsigned long *)(IO_ADDR (port))) = b;
 153 }
 154
 155
 156 unsigned int
 157 _inb (unsigned long int port)
 158 {
 159   return *((volatile unsigned char *)(IO_ADDR (port)));
 160 }
 161
 162
 163 unsigned int
 164 _inw (unsigned long int port)
 165 {
 166   return *((volatile unsigned short *)(IO_ADDR (port)));
 167 }
 168
 169
 170 unsigned int
 171 _inl (unsigned long int port)
 172 {
 173   return *((volatile unsigned long *)(IO_ADDR (port)));
 174 }
 175
 176 weak_alias (_ioperm, ioperm);
 177 weak_alias (_iopl, iopl);
 178 weak_alias (_inb, inb);
 179 weak_alias (_inw, inw);
 180 weak_alias (_inl, inl);
 181 weak_alias (_outb, outb);
 182 weak_alias (_outw, outw);
 183 weak_alias (_outl, outl);