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

   1 /* Copyright (C) 1998, 1999, 2003, 2005, 2008, 2011
   2    Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Phil Blundell, based on the Alpha version by
   5    David Mosberger.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library.  If not, see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21 /* I/O port access on the ARM is something of a fiction.  What we do is to
  22    map an appropriate area of /dev/mem into user space so that a program
  23    can blast away at the hardware in such a way as to generate I/O cycles
  24    on the bus.  To insulate user code from dependencies on particular
  25    hardware we don't allow calls to inb() and friends to be inlined, but
  26    force them to come through code in here every time.  Performance-critical
  27    registers tend to be memory mapped these days so this should be no big
  28    problem.  */
  29
  30 /* Once upon a time this file used mprotect to enable and disable
  31    access to particular areas of I/O space.  Unfortunately the
  32    mprotect syscall also has the side effect of enabling caching for
  33    the area affected (this is a kernel limitation).  So we now just
  34    enable all the ports all of the time.  */
  35
  36 #include <errno.h>
  37 #include <fcntl.h>
  38 #include <stdio.h>
  39 #include <ctype.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42 #include <unistd.h>
  43
  44 #include <sys/types.h>
  45 #include <sys/mman.h>
  46
  47 #include <linux/version.h>
  48 #include <sys/sysctl.h>
  49
  50 #define PATH_ARM_SYSTYPE        "/etc/arm_systype"
  51 #define PATH_CPUINFO            "/proc/cpuinfo"
  52
  53 #define MAX_PORT        0x10000
  54
  55 static struct {
  56   unsigned long int     base;
  57   unsigned long int     io_base;
  58   unsigned int          shift;
  59   unsigned int          initdone;       /* since all the above could be 0 */
  60 } io;
  61
  62 #define IO_BASE_FOOTBRIDGE      0x7c000000
  63 #define IO_SHIFT_FOOTBRIDGE     0
  64
  65 static struct platform {
  66   const char            *name;
  67   unsigned long int     io_base;
  68   unsigned int          shift;
  69 } platform[] = {
  70   /* All currently supported platforms are in fact the same. :-)  */
  71   {"Chalice-CATS",      IO_BASE_FOOTBRIDGE,     IO_SHIFT_FOOTBRIDGE},
  72   {"DEC-EBSA285",       IO_BASE_FOOTBRIDGE,     IO_SHIFT_FOOTBRIDGE},
  73   {"Corel-NetWinder",   IO_BASE_FOOTBRIDGE,     IO_SHIFT_FOOTBRIDGE},
  74   {"Rebel-NetWinder",   IO_BASE_FOOTBRIDGE,     IO_SHIFT_FOOTBRIDGE},
  75 };
  76
  77 #define IO_ADDR(port)   (io.base + ((port) << io.shift))
  78
  79 /*
  80  * Initialize I/O system.  There are several ways to get the information
  81  * we need.  Each is tried in turn until one succeeds.
  82  *
  83  * 1. Sysctl (CTL_BUS, CTL_BUS_ISA, ISA_*).  This is the preferred method
  84  *    but not all kernels support it.
  85  *
  86  * 2. Read the value (not the contents) of symlink PATH_ARM_SYSTYPE.
  87  *    - If it matches one of the entries in the table above, use the
  88  *      corresponding values.
  89  *    - If it begins with a number, assume this is a previously
  90  *      unsupported system and the values encode, in order,
  91  *      "<io_base>,<port_shift>".
  92  *
  93  * 3. Lookup the "system type" field in /proc/cpuinfo.  Again, if it
  94  *    matches an entry in the platform[] table, use the corresponding
  95  *    values.
  96  */
  97
  98 /* The Linux kernel headers renamed this constant between 2.5.26 and
  99    2.5.27.  It was backported to 2.4 between 2.4.22 and 2.4.23.  */
 100 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,23)
 101 # define BUS_ISA CTL_BUS_ISA
 102 #endif
 103
 104 static int
 105 init_iosys (void)
 106 {
 107   char systype[256];
 108   int i, n;
 109   static int iobase_name[] = { CTL_BUS, BUS_ISA, BUS_ISA_PORT_BASE };
 110   static int ioshift_name[] = { CTL_BUS, BUS_ISA, BUS_ISA_PORT_SHIFT };
 111   size_t len = sizeof(io.base);
 112
 113   if (! __sysctl (iobase_name, 3, &io.io_base, &len, NULL, 0)
 114       && ! __sysctl (ioshift_name, 3, &io.shift, &len, NULL, 0))
 115     {
 116       io.initdone = 1;
 117       return 0;
 118     }
 119
 120   n = __readlink (PATH_ARM_SYSTYPE, systype, sizeof (systype) - 1);
 121   if (n > 0)
 122     {
 123       systype[n] = '\0';
 124       if (isdigit (systype[0]))
 125         {
 126           if (sscanf (systype, "%li,%i", &io.io_base, &io.shift) == 2)
 127             {
 128               io.initdone = 1;
 129               return 0;
 130             }
 131           /* else we're likely going to fail with the system match below */
 132         }
 133     }
 134   else
 135     {
 136       FILE * fp;
 137
 138       fp = fopen (PATH_CPUINFO, "rce");
 139       if (! fp)
 140         return -1;
 141       while ((n = fscanf (fp, "Hardware\t: %256[^\n]\n", systype))
 142              != EOF)
 143         {
 144           if (n == 1)
 145             break;
 146           else
 147             fgets_unlocked (systype, 256, fp);
 148         }
 149       fclose (fp);
 150
 151       if (n == EOF)
 152         {
 153           /* this can happen if the format of /proc/cpuinfo changes...  */
 154           fprintf (stderr,
 155                    "ioperm: Unable to determine system type.\n"
 156                    "\t(May need " PATH_ARM_SYSTYPE " symlink?)\n");
 157           __set_errno (ENODEV);
 158           return -1;
 159         }
 160     }
 161
 162   /* translate systype name into i/o system: */
 163   for (i = 0; i < sizeof (platform) / sizeof (platform[0]); ++i)
 164     {
 165       if (strcmp (platform[i].name, systype) == 0)
 166         {
 167           io.shift = platform[i].shift;
 168           io.io_base = platform[i].io_base;
 169           io.initdone = 1;
 170           return 0;
 171         }
 172     }
 173
 174   /* systype is not a known platform name... */
 175   __set_errno (ENODEV);
 176   return -1;
 177 }
 178
 179 int
 180 _ioperm (unsigned long int from, unsigned long int num, int turn_on)
 181 {
 182   if (! io.initdone && init_iosys () < 0)
 183     return -1;
 184
 185   /* this test isn't as silly as it may look like; consider overflows! */
 186   if (from >= MAX_PORT || from + num > MAX_PORT)
 187     {
 188       __set_errno (EINVAL);
 189       return -1;
 190     }
 191
 192   if (turn_on)
 193     {
 194       if (! io.base)
 195         {
 196           int fd;
 197
 198           fd = __open ("/dev/mem", O_RDWR);
 199           if (fd < 0)
 200             return -1;
 201
 202           io.base =
 203             (unsigned long int) __mmap (0, MAX_PORT << io.shift,
 204                                         PROT_READ | PROT_WRITE,
 205                                         MAP_SHARED, fd, io.io_base);
 206           __close (fd);
 207           if ((long) io.base == -1)
 208             return -1;
 209         }
 210     }
 211
 212   return 0;
 213 }
 214
 215
 216 int
 217 _iopl (unsigned int level)
 218 {
 219     if (level > 3)
 220       {
 221         __set_errno (EINVAL);
 222         return -1;
 223       }
 224     if (level)
 225       {
 226         return _ioperm (0, MAX_PORT, 1);
 227       }
 228     return 0;
 229 }
 230
 231
 232 void
 233 _outb (unsigned char b, unsigned long int port)
 234 {
 235   *((volatile unsigned char *)(IO_ADDR (port))) = b;
 236 }
 237
 238
 239 void
 240 _outw (unsigned short b, unsigned long int port)
 241 {
 242   *((volatile unsigned short *)(IO_ADDR (port))) = b;
 243 }
 244
 245
 246 void
 247 _outl (unsigned int b, unsigned long int port)
 248 {
 249   *((volatile unsigned long *)(IO_ADDR (port))) = b;
 250 }
 251
 252
 253 unsigned int
 254 _inb (unsigned long int port)
 255 {
 256   return *((volatile unsigned char *)(IO_ADDR (port)));
 257 }
 258
 259
 260 unsigned int
 261 _inw (unsigned long int port)
 262 {
 263   return *((volatile unsigned short *)(IO_ADDR (port)));
 264 }
 265
 266
 267 unsigned int
 268 _inl (unsigned long int port)
 269 {
 270   return *((volatile unsigned long *)(IO_ADDR (port)));
 271 }
 272
 273 weak_alias (_ioperm, ioperm);
 274 weak_alias (_iopl, iopl);
 275 weak_alias (_inb, inb);
 276 weak_alias (_inw, inw);
 277 weak_alias (_inl, inl);
 278 weak_alias (_outb, outb);
 279 weak_alias (_outw, outw);
 280 weak_alias (_outl, outl);