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

/* Copyright (C) 1998 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 Library General Public License as
   published by the Free Software Foundation; either version 2 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

/* 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.  */

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <sys/types.h>
#include <sys/mman.h>

#include <asm/page.h>

#define PATH_ARM_SYSTYPE	"/etc/arm_systype"
#define PATH_CPUINFO		"/proc/cpuinfo"

#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_BASE_FOOTBRIDGE	0x7c000000
#define IO_SHIFT_FOOTBRIDGE	0

static struct platform {
  const char		*name;
  unsigned long int	io_base;
  unsigned int		shift;
} platform[] = {
  /* All currently supported platforms are in fact the same. :-)  */
  {"Chalice-CATS",	IO_BASE_FOOTBRIDGE,	IO_SHIFT_FOOTBRIDGE},
  {"DEC-EBSA285",	IO_BASE_FOOTBRIDGE,	IO_SHIFT_FOOTBRIDGE},
  {"Corel-NetWinder",	IO_BASE_FOOTBRIDGE,	IO_SHIFT_FOOTBRIDGE},
};

#define IO_ADDR(port)	(io.base + ((port) << io.shift))

/*
 * Initialize I/O system.  To determine what I/O system we're dealing
 * with, we first try to read the value of symlink PATH_ARM_SYSTYPE,
 * if that fails, we lookup the "system type" field in /proc/cpuinfo.
 * If that fails as well, we give up.  Other possible options might be
 * to look at the ELF auxiliary vector or to add a special system call
 * but there is probably no point.
 *
 * If the value received from PATH_ARM_SYSTYPE begins with a number,
 * assume this is a previously unsupported system and the values encode,
 * in order, "<io_base>,<port_shift>".
 */

static int
init_iosys (void)
{
  char systype[256];
  int i, n;

  n = readlink (PATH_ARM_SYSTYPE, systype, sizeof (systype) - 1);
  if (n > 0)
    {
      systype[n] = '\0';
      if (isdigit (systype[0]))
	{
	  if (sscanf (systype, "%li,%i", &io.io_base, &io.shift) == 2)
	    {
	      io.initdone = 1;
	      return 0;
	    }
	  /* else we're likely going to fail with the system match below */
	}
    }
  else
    {
      FILE * fp;

      fp = fopen (PATH_CPUINFO, "r");
      if (!fp)
	return -1;
      while ((n = fscanf (fp, "Hardware\t: %256[^\n]\n", systype))
	     != EOF)
	{
	  if (n == 1)
	    break;
	  else
	    fgets (systype, 256, fp);
	}
      fclose (fp);

      if (n == EOF)
	{
	  /* this can happen if the format of /proc/cpuinfo changes...  */
	  fprintf (stderr,
		   "ioperm: Unable to determine system type.\n"
		   "\t(May need " PATH_ARM_SYSTYPE " symlink?)\n");
	  __set_errno (ENODEV);
	  return -1;
	}
    }

  /* translate systype name into i/o system: */
  for (i = 0; i < sizeof (platform) / sizeof (platform[0]); ++i)
    {
      if (strcmp (platform[i].name, systype) == 0)
	{
	  io.shift = platform[i].shift;
	  io.io_base = platform[i].io_base;
	  io.initdone = 1;
	  return 0;
	}
    }

  /* systype is not a known platform name... */
  __set_errno (EINVAL);
  return -1;
}

int
_ioperm (unsigned long int from, unsigned long int num, int turn_on)
{
  unsigned long int addr, len;
  int prot;

  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_NONE, 
					MAP_SHARED, fd, io.io_base);
	  close (fd);
	  if ((long) io.base == -1)
	    return -1;
	}
      prot = PROT_READ | PROT_WRITE;
    }
  else
    {
      if (!io.base)
	return 0;	/* never was turned on... */

      /* turnoff access to relevant pages: */
      prot = PROT_NONE;
    }
  addr = (io.base + (from << io.shift)) & PAGE_MASK;
  len = num << io.shift;
  return mprotect ((void *) addr, len, prot);
}


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)
{
  if (port >= MAX_PORT)
    return;

  *((volatile unsigned char *)(IO_ADDR (port))) = b;
}


void
_outw (unsigned short b, unsigned long int port)
{
  if (port >= MAX_PORT)
    return;

  *((volatile unsigned short *)(IO_ADDR (port))) = b;
}


void
_outl (unsigned int b, unsigned long int port)
{
  if (port >= MAX_PORT)
    return;

  *((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);