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

   1 /* Copyright (C) 1998-2015 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 <string.h>
  41 #include <unistd.h>
  42
  43 #include <sys/types.h>
  44 #include <sys/mman.h>
  45
  46 #include <linux/version.h>
  47 #include <sys/sysctl.h>
  48
  49 #define PATH_ARM_SYSTYPE        "/etc/arm_systype"
  50 #define PATH_CPUINFO            "/proc/cpuinfo"
  51
  52 #define MAX_PORT        0x10000
  53
  54 static struct {
  55   unsigned long int     base;
  56   unsigned long int     io_base;
  57   unsigned int          shift;
  58   unsigned int          initdone;       /* since all the above could be 0 */
  59 } io;
  60
  61 #define IO_BASE_FOOTBRIDGE      0x7c000000
  62 #define IO_SHIFT_FOOTBRIDGE     0
  63
  64 static struct platform {
  65   const char            *name;
  66   unsigned long int     io_base;
  67   unsigned int          shift;
  68 } platform[] = {
  69   /* All currently supported platforms are in fact the same. :-)  */
  70   {"Chalice-CATS",      IO_BASE_FOOTBRIDGE,     IO_SHIFT_FOOTBRIDGE},
  71   {"DEC-EBSA285",       IO_BASE_FOOTBRIDGE,     IO_SHIFT_FOOTBRIDGE},
  72   {"Corel-NetWinder",   IO_BASE_FOOTBRIDGE,     IO_SHIFT_FOOTBRIDGE},
  73   {"Rebel-NetWinder",   IO_BASE_FOOTBRIDGE,     IO_SHIFT_FOOTBRIDGE},
  74 };
  75
  76 #define IO_ADDR(port)   (io.base + ((port) << io.shift))
  77
  78 /*
  79  * Initialize I/O system.  There are several ways to get the information
  80  * we need.  Each is tried in turn until one succeeds.
  81  *
  82  * 1. Sysctl (CTL_BUS, CTL_BUS_ISA, ISA_*).  This is the preferred method
  83  *    but not all kernels support it.
  84  *
  85  * 2. Read the value (not the contents) of symlink PATH_ARM_SYSTYPE.
  86  *    - If it matches one of the entries in the table above, use the
  87  *      corresponding values.
  88  *    - If it begins with a number, assume this is a previously
  89  *      unsupported system and the values encode, in order,
  90  *      "<io_base>,<port_shift>".
  91  *
  92  * 3. Lookup the "system type" field in /proc/cpuinfo.  Again, if it
  93  *    matches an entry in the platform[] table, use the corresponding
  94  *    values.
  95  */
  96
  97 /* The Linux kernel headers renamed this constant between 2.5.26 and
  98    2.5.27.  It was backported to 2.4 between 2.4.22 and 2.4.23.  */
  99 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,23)
 100 # define BUS_ISA CTL_BUS_ISA
 101 #endif
 102
 103 static int
 104 init_iosys (void)
 105 {
 106   char systype[256];
 107   int i, n;
 108   static int iobase_name[] = { CTL_BUS, BUS_ISA, BUS_ISA_PORT_BASE };
 109   static int ioshift_name[] = { CTL_BUS, BUS_ISA, BUS_ISA_PORT_SHIFT };
 110   size_t len = sizeof(io.base);
 111
 112   if (! __sysctl (iobase_name, 3, &io.io_base, &len, NULL, 0)
 113       && ! __sysctl (ioshift_name, 3, &io.shift, &len, NULL, 0))
 114     {
 115       io.initdone = 1;
 116       return 0;
 117     }
 118
 119   n = __readlink (PATH_ARM_SYSTYPE, systype, sizeof (systype) - 1);
 120   if (n > 0)
 121     {
 122       systype[n] = '\0';
 123       if (isdigit (systype[0]))
 124         {
 125           if (sscanf (systype, "%li,%i", &io.io_base, &io.shift) == 2)
 126             {
 127               io.initdone = 1;
 128               return 0;
 129             }
 130           /* else we're likely going to fail with the system match below */
 131         }
 132     }
 133   else
 134     {
 135       FILE * fp;
 136
 137       fp = fopen (PATH_CPUINFO, "rce");
 138       if (! fp)
 139         return -1;
 140       while ((n = fscanf (fp, "Hardware\t: %256[^\n]\n", systype))
 141              != EOF)
 142         {
 143           if (n == 1)
 144             break;
 145           else
 146             fgets_unlocked (systype, 256, fp);
 147         }
 148       fclose (fp);
 149
 150       if (n == EOF)
 151         {
 152           /* this can happen if the format of /proc/cpuinfo changes...  */
 153           fprintf (stderr,
 154                    "ioperm: Unable to determine system type.\n"
 155                    "\t(May need " PATH_ARM_SYSTYPE " symlink?)\n");
 156           __set_errno (ENODEV);
 157           return -1;
 158         }
 159     }
 160
 161   /* translate systype name into i/o system: */
 162   for (i = 0; i < sizeof (platform) / sizeof (platform[0]); ++i)
 163     {
 164       if (strcmp (platform[i].name, systype) == 0)
 165         {
 166           io.shift = platform[i].shift;
 167           io.io_base = platform[i].io_base;
 168           io.initdone = 1;
 169           return 0;
 170         }
 171     }
 172
 173   /* systype is not a known platform name... */
 174   __set_errno (ENODEV);
 175   return -1;
 176 }
 177
 178 int
 179 _ioperm (unsigned long int from, unsigned long int num, int turn_on)
 180 {
 181   if (! io.initdone && init_iosys () < 0)
 182     return -1;
 183
 184   /* this test isn't as silly as it may look like; consider overflows! */
 185   if (from >= MAX_PORT || from + num > MAX_PORT)
 186     {
 187       __set_errno (EINVAL);
 188       return -1;
 189     }
 190
 191   if (turn_on)
 192     {
 193       if (! io.base)
 194         {
 195           int fd;
 196
 197           fd = __open ("/dev/mem", O_RDWR);
 198           if (fd < 0)
 199             return -1;
 200
 201           io.base =
 202             (unsigned long int) __mmap (0, MAX_PORT << io.shift,
 203                                         PROT_READ | PROT_WRITE,
 204                                         MAP_SHARED, fd, io.io_base);
 205           __close (fd);
 206           if ((long) io.base == -1)
 207             return -1;
 208         }
 209     }
 210
 211   return 0;
 212 }
 213
 214
 215 int
 216 _iopl (unsigned int level)
 217 {
 218     if (level > 3)
 219       {
 220         __set_errno (EINVAL);
 221         return -1;
 222       }
 223     if (level)
 224       {
 225         return _ioperm (0, MAX_PORT, 1);
 226       }
 227     return 0;
 228 }
 229
 230
 231 void
 232 _outb (unsigned char b, unsigned long int port)
 233 {
 234   *((volatile unsigned char *)(IO_ADDR (port))) = b;
 235 }
 236
 237
 238 void
 239 _outw (unsigned short b, unsigned long int port)
 240 {
 241   *((volatile unsigned short *)(IO_ADDR (port))) = b;
 242 }
 243
 244
 245 void
 246 _outl (unsigned int b, unsigned long int port)
 247 {
 248   *((volatile unsigned long *)(IO_ADDR (port))) = b;
 249 }
 250
 251
 252 unsigned int
 253 _inb (unsigned long int port)
 254 {
 255   return *((volatile unsigned char *)(IO_ADDR (port)));
 256 }
 257
 258
 259 unsigned int
 260 _inw (unsigned long int port)
 261 {
 262   return *((volatile unsigned short *)(IO_ADDR (port)));
 263 }
 264
 265
 266 unsigned int
 267 _inl (unsigned long int port)
 268 {
 269   return *((volatile unsigned long *)(IO_ADDR (port)));
 270 }
 271
 272 weak_alias (_ioperm, ioperm);
 273 weak_alias (_iopl, iopl);
 274 weak_alias (_inb, inb);
 275 weak_alias (_inw, inw);
 276 weak_alias (_inl, inl);
 277 weak_alias (_outb, outb);
 278 weak_alias (_outw, outw);
 279 weak_alias (_outl, outl);