Add a common get_ram_size() function and modify the the

[karo-tx-uboot.git] / common / memsize.c

diff --git a/common/memsize.c b/common/memsize.c
new file mode 100644 (file)
index 0000000..dbc812d
--- /dev/null
+++ b/common/memsize.c
@@ -0,0 +1,77 @@
+/*
+ * (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
+ */
+
+
+/*
+ * 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! */
+               save[i++] = *addr;
+               *addr = ~cnt;
+       }
+
+       addr = base;
+       save[i] = *addr;
+       *addr = 0;
+
+       if ((val = *addr) != 0) {
+               /* Restore the original data before leaving the function.
+                */
+               *addr = save[i];
+               for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) {
+                       addr  = base + cnt;
+                       *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);
+}