common: Add get_effective_memsize() to memsize.c

This function has been around for powerpc. It is used for systems with
memory more than CONFIG_MAX_MEM_MAPPED. In case of non-contiguous memory,
this feature can limit U-boot to one block without going over the limit.

Signed-off-by: York Sun <yorksun@freescale.com>
Acked-by: Albert ARIBAUD <albert.u.boot@aribaud.net>

common/memsize.c

@@ -5,7 +5,10 @@
  * SPDX-License-Identifier:	GPL-2.0+
  */
 
-#include <config.h>
+#include <common.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
 #ifdef __PPC__
 /*
  * At least on G2 PowerPC cores, sequential accesses to non-existent
@@ -76,3 +79,14 @@ long get_ram_size(long *base, long maxsize)
 
 	return (maxsize);
 }
+
+phys_size_t __weak get_effective_memsize(void)
+{
+#ifndef CONFIG_VERY_BIG_RAM
+	return gd->ram_size;
+#else
+	/* limit stack to what we can reasonable map */
+	return ((gd->ram_size > CONFIG_MAX_MEM_MAPPED) ?
+		CONFIG_MAX_MEM_MAPPED : gd->ram_size);
+#endif
+}