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Diffstat (limited to 'src/mainboard/emulation/qemu-armv7/cbmem.c')
-rw-r--r--src/mainboard/emulation/qemu-armv7/cbmem.c46
1 files changed, 45 insertions, 1 deletions
diff --git a/src/mainboard/emulation/qemu-armv7/cbmem.c b/src/mainboard/emulation/qemu-armv7/cbmem.c
index a626ec6adf..f26ca6cd20 100644
--- a/src/mainboard/emulation/qemu-armv7/cbmem.c
+++ b/src/mainboard/emulation/qemu-armv7/cbmem.c
@@ -14,8 +14,52 @@
#include <stddef.h>
#include <cbmem.h>
#include <symbols.h>
+#include <arch/io.h>
+#include "mainboard.h"
+
+#define PATTERN1 0x55
+#define PATTERN2 0xaa
+
+/* Returns 1 if mebibyte mb is present and 0 otherwise. */
+static int probe_mb(int mb)
+{
+ char *ptr = (char *) 0x60000000 + (mb << 20) + 0xfffff;
+ char old;
+ if (ptr < (char *) &_eprogram) {
+ /* Don't probe below _end to avoid accidentally clobering
+ oneself. */
+ return 1;
+ }
+
+ old = read8(ptr);
+ write8(ptr, PATTERN1);
+ if (read8(ptr) != PATTERN1)
+ return 0;
+ write8(ptr, PATTERN2);
+ if (read8(ptr) != PATTERN2)
+ return 0;
+ write8(ptr, old);
+ return 1;
+}
+
+int probe_ramsize(void)
+{
+ int i;
+ int discovered = 0;
+ static int saved_result;
+ if (saved_result)
+ return saved_result;
+ /* Compact binary search. */
+ /* 1 GiB is the largest supported RAM by this machine. */
+ for (i = 9; i >= 0; i--)
+ if (probe_mb(discovered | (1 << i)))
+ discovered |= (1 << i);
+ discovered++;
+ saved_result = discovered;
+ return discovered;
+}
void *cbmem_top(void)
{
- return _dram + (CONFIG_DRAM_SIZE_MB << 20);
+ return _dram + (probe_ramsize() << 20);
}