source: SVN/rincon/u-boot/common/memsize.c @ 55

Last change on this file since 55 was 55, checked in by Tim Harvey, 2 years ago

rincon: added latest u-boot source

restored form server backup

Signed-off-by: Tim Harvey <tharvey@…>

File size: 2.3 KB
Line 
1/*
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
24#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
34
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 */
40long get_ram_size(volatile long *base, long maxsize)
41{
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! */
51                sync ();
52                save[i++] = *addr;
53                sync ();
54                *addr = ~cnt;
55        }
56
57        addr = base;
58        sync ();
59        save[i] = *addr;
60        sync ();
61        *addr = 0;
62
63        sync ();
64        if ((val = *addr) != 0) {
65                /* Restore the original data before leaving the function.
66                 */
67                sync ();
68                *addr = save[i];
69                for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) {
70                        addr  = base + cnt;
71                        sync ();
72                        *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}
Note: See TracBrowser for help on using the repository browser.