95 lines
2.3 KiB
C
95 lines
2.3 KiB
C
/*
|
|
* (C) Copyright 2004
|
|
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
|
|
*
|
|
* See file CREDITS for list of people who contributed to this
|
|
* project.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License as
|
|
* published by the Free Software Foundation; either version 2 of
|
|
* the License, or (at your option) any later version.
|
|
*
|
|
* This program 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 General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
|
|
* MA 02111-1307 USA
|
|
*/
|
|
|
|
#include <config.h>
|
|
#ifdef __PPC__
|
|
/*
|
|
* At least on G2 PowerPC cores, sequential accesses to non-existent
|
|
* memory must be synchronized.
|
|
*/
|
|
# include <asm/io.h> /* for sync() */
|
|
#else
|
|
# define sync() /* nothing */
|
|
#endif
|
|
|
|
/*
|
|
* Check memory range for valid RAM. A simple memory test determines
|
|
* the actually available RAM size between addresses `base' and
|
|
* `base + maxsize'.
|
|
*/
|
|
long get_ram_size(volatile long *base, long maxsize)
|
|
{
|
|
volatile long *addr;
|
|
long save[32];
|
|
long cnt;
|
|
long val;
|
|
long size;
|
|
int i = 0;
|
|
|
|
for (cnt = (maxsize / sizeof (long)) >> 1; cnt > 0; cnt >>= 1) {
|
|
addr = base + cnt; /* pointer arith! */
|
|
sync ();
|
|
save[i++] = *addr;
|
|
sync ();
|
|
*addr = ~cnt;
|
|
}
|
|
|
|
addr = base;
|
|
sync ();
|
|
save[i] = *addr;
|
|
sync ();
|
|
*addr = 0;
|
|
|
|
sync ();
|
|
if ((val = *addr) != 0) {
|
|
/* Restore the original data before leaving the function.
|
|
*/
|
|
sync ();
|
|
*addr = save[i];
|
|
for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) {
|
|
addr = base + cnt;
|
|
sync ();
|
|
*addr = save[--i];
|
|
}
|
|
return (0);
|
|
}
|
|
|
|
for (cnt = 1; cnt < maxsize / sizeof (long); cnt <<= 1) {
|
|
addr = base + cnt; /* pointer arith! */
|
|
val = *addr;
|
|
*addr = save[--i];
|
|
if (val != ~cnt) {
|
|
size = cnt * sizeof (long);
|
|
/* Restore the original data before leaving the function.
|
|
*/
|
|
for (cnt <<= 1; cnt < maxsize / sizeof (long); cnt <<= 1) {
|
|
addr = base + cnt;
|
|
*addr = save[--i];
|
|
}
|
|
return (size);
|
|
}
|
|
}
|
|
|
|
return (maxsize);
|
|
}
|