Implementation of inb, outb etc for ARM systems.

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

@@ -0,0 +1,271 @@
+/* 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);