text: /* Copyright (C) 1998-2019 Free Software Foundation, Inc.
     This file is part of the GNU C Library.
     Contributed by Phil Blundell, based on the Alpha version by
     David Mosberger.
  
     The GNU C Library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
     License as published by the Free Software Foundation; either
     version 2.1 of the License, or (at your option) any later version.
  
     The GNU C Library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public
     License along with the GNU C Library.  If not, see
     <http://www.gnu.org/licenses/>.  */
  
  /* I/O port access on the ARM is something of a fiction.  What we do is to
     map an appropriate area of /dev/mem into user space so that a program
     can blast away at the hardware in such a way as to generate I/O cycles
     on the bus.  To insulate user code from dependencies on particular
     hardware we don't allow calls to inb() and friends to be inlined, but
     force them to come through code in here every time.  Performance-critical
     registers tend to be memory mapped these days so this should be no big
     problem.  */
  
  /* Once upon a time this file used mprotect to enable and disable
     access to particular areas of I/O space.  Unfortunately the
     mprotect syscall also has the side effect of enabling caching for
     the area affected (this is a kernel limitation).  So we now just
     enable all the ports all of the time.  */
  
  #include <ctype.h>
  #include <errno.h>
  #include <fcntl.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <sys/mman.h>
  #include <sys/sysctl.h>
  #include <sys/types.h>
  #include <unistd.h>
  
  #define MAX_PORT 0x10000
  
  static struct
  {
      unsigned long int base;
      unsigned long int io_base;
      unsigned int shift;
      unsigned int initdone; /* since all the above could be 0 */
  } io;
  
  #define IO_ADDR(port) (io.base + ((port) << io.shift))
  
  /*
   * Initialize I/O system.  The io_bae and port_shift values are fetched
   * using sysctl (CTL_BUS, CTL_BUS_ISA, ISA_*).
   */
  
  static int init_iosys(void)
  {
      static int iobase_name[] = {CTL_BUS, CTL_BUS_ISA, BUS_ISA_PORT_BASE};
      static int ioshift_name[] = {CTL_BUS, CTL_BUS_ISA, BUS_ISA_PORT_SHIFT};
      size_t len = sizeof(io.base);
  
      if (!__sysctl(iobase_name, 3, &io.io_base, &len, NULL, 0) &&
          !__sysctl(ioshift_name, 3, &io.shift, &len, NULL, 0))
      {
          io.initdone = 1;
          return 0;
      }
  
      /* sysctl has failed... */
      __set_errno(ENODEV);
      return -1;
  }
  
  int _ioperm(unsigned long int from, unsigned long int num, int turn_on)
  {
      if (!io.initdone && init_iosys() < 0)
          return -1;
  
      /* this test isn't as silly as it may look like; consider overflows! */
      if (from >= MAX_PORT || from + num > MAX_PORT)
      {
          __set_errno(EINVAL);
          return -1;
      }
  
      if (turn_on)
      {
          if (!io.base)
          {
              int fd;
  
              fd = __open("/dev/mem", O_RDWR);
              if (fd < 0)
                  return -1;
  
              io.base = (unsigned long int)__mmap(0, MAX_PORT << io.shift,
                                                  PROT_READ | PROT_WRITE,
                                                  MAP_SHARED, fd, io.io_base);
              __close(fd);
              if ((long)io.base == -1)
                  return -1;
          }
      }
  
      return 0;
  }
  
  int _iopl(unsigned int level)
  {
      if (level > 3)
      {
          __set_errno(EINVAL);
          return -1;
      }
      if (level)
      {
          return _ioperm(0, MAX_PORT, 1);
      }
      return 0;
  }
  
  void _outb(unsigned char b, unsigned long int port)
  {
      *((volatile unsigned char*)(IO_ADDR(port))) = b;
  }
  
  void _outw(unsigned short b, unsigned long int port)
  {
      *((volatile unsigned short*)(IO_ADDR(port))) = b;
  }
  
  void _outl(unsigned int b, unsigned long int port)
  {
      *((volatile unsigned long*)(IO_ADDR(port))) = b;
  }
  
  unsigned int _inb(unsigned long int port)
  {
      return *((volatile unsigned char*)(IO_ADDR(port)));
  }
  
  unsigned int _inw(unsigned long int port)
  {
      return *((volatile unsigned short*)(IO_ADDR(port)));
  }
  
  unsigned int _inl(unsigned long int port)
  {
      return *((volatile unsigned long*)(IO_ADDR(port)));
  }
  
  weak_alias(_ioperm, ioperm);
  weak_alias(_iopl, iopl);
  weak_alias(_inb, inb);
  weak_alias(_inw, inw);
  weak_alias(_inl, inl);
  weak_alias(_outb, outb);
  weak_alias(_outw, outw);
  weak_alias(_outl, outl);
  