blob: 963e4f35b18059c3d79b30c04ab595281c37273e [file] [log] [blame]
wdenkc83bf6a2004-01-06 22:38:14 +00001/*
2 * (C) Copyright 2004
3 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4 *
5 * See file CREDITS for list of people who contributed to this
6 * project.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of
11 * the License, or (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21 * MA 02111-1307 USA
22 */
23
Wolfgang Denk91650b32006-11-06 17:06:36 +010024#include <config.h>
25#ifdef __PPC__
26/*
27 * At least on G2 PowerPC cores, sequential accesses to non-existent
28 * memory must be synchronized.
29 */
30# include <asm/io.h> /* for sync() */
31#else
32# define sync() /* nothing */
33#endif
wdenkc83bf6a2004-01-06 22:38:14 +000034
35/*
36 * Check memory range for valid RAM. A simple memory test determines
37 * the actually available RAM size between addresses `base' and
38 * `base + maxsize'.
39 */
Albert ARIBAUDa55d23c2011-07-03 05:55:33 +000040long get_ram_size(long *base, long maxsize)
wdenkc83bf6a2004-01-06 22:38:14 +000041{
42 volatile long *addr;
43 long save[32];
44 long cnt;
45 long val;
46 long size;
47 int i = 0;
48
49 for (cnt = (maxsize / sizeof (long)) >> 1; cnt > 0; cnt >>= 1) {
50 addr = base + cnt; /* pointer arith! */
Wolfgang Denk91650b32006-11-06 17:06:36 +010051 sync ();
wdenkc83bf6a2004-01-06 22:38:14 +000052 save[i++] = *addr;
Wolfgang Denk91650b32006-11-06 17:06:36 +010053 sync ();
wdenkc83bf6a2004-01-06 22:38:14 +000054 *addr = ~cnt;
55 }
56
57 addr = base;
Wolfgang Denk91650b32006-11-06 17:06:36 +010058 sync ();
wdenkc83bf6a2004-01-06 22:38:14 +000059 save[i] = *addr;
Wolfgang Denk91650b32006-11-06 17:06:36 +010060 sync ();
wdenkc83bf6a2004-01-06 22:38:14 +000061 *addr = 0;
62
Wolfgang Denk91650b32006-11-06 17:06:36 +010063 sync ();
wdenkc83bf6a2004-01-06 22:38:14 +000064 if ((val = *addr) != 0) {
65 /* Restore the original data before leaving the function.
66 */
Wolfgang Denk91650b32006-11-06 17:06:36 +010067 sync ();
wdenkc83bf6a2004-01-06 22:38:14 +000068 *addr = save[i];
69 for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) {
70 addr = base + cnt;
Wolfgang Denk91650b32006-11-06 17:06:36 +010071 sync ();
wdenkc83bf6a2004-01-06 22:38:14 +000072 *addr = save[--i];
73 }
74 return (0);
75 }
76
77 for (cnt = 1; cnt < maxsize / sizeof (long); cnt <<= 1) {
78 addr = base + cnt; /* pointer arith! */
79 val = *addr;
80 *addr = save[--i];
81 if (val != ~cnt) {
82 size = cnt * sizeof (long);
83 /* Restore the original data before leaving the function.
84 */
85 for (cnt <<= 1; cnt < maxsize / sizeof (long); cnt <<= 1) {
86 addr = base + cnt;
87 *addr = save[--i];
88 }
89 return (size);
90 }
91 }
92
93 return (maxsize);
94}