Sequential accesses to non-existent memory must be synchronized,

at least on G2 cores.

This fixes get_ram_size() problems on MPC5200 Rev. B boards.

board/mcc200/mcc200.c

@@ -27,6 +27,7 @@
 #include <common.h>
 #include <mpc5xxx.h>
 #include <pci.h>
+#include <asm/processor.h>
 
 /* Two MT48LC8M32B2 for 32 MB */
 /* #include "mt48lc8m32b2-6-7.h" */
@@ -98,6 +99,7 @@ long int initdram (int board_type)
 {
 	ulong dramsize = 0;
 	ulong dramsize2 = 0;
+	uint svr, pvr;
 #ifndef CFG_RAMBOOT
 	ulong test1, test2;
 
@@ -192,6 +194,23 @@ long int initdram (int board_type)
 
 #endif /* CFG_RAMBOOT */
 
+	/*
+	 * On MPC5200B we need to set the special configuration delay in the
+	 * DDR controller. Please refer to Freescale's AN3221 "MPC5200B SDRAM
+	 * Initialization and Configuration", 3.3.1 SDelay--MBAR + 0x0190:
+	 *
+	 * "The SDelay should be written to a value of 0x00000004. It is
+	 * required to account for changes caused by normal wafer processing
+	 * parameters."
+	 */
+	svr = get_svr();
+	pvr = get_pvr();
+	if ((SVR_MJREV(svr) >= 2) && (PVR_MAJ(pvr) == 1) && 
+	    (PVR_MIN(pvr) == 4)) {
+		*(vu_long *)MPC5XXX_SDRAM_SDELAY = 0x04;
+		__asm__ volatile ("sync");
+	}
+
 	return dramsize + dramsize2;
 }
 

common/memsize.c

@@ -21,6 +21,16 @@
  * MA 02111-1307 USA
  */
 
+#include <config.h>
+#ifdef __PPC__
+/*
+ * At least on G2 PowerPC cores, sequential accesses to non-existent
+ * memory must be synchronized.
+ */
+# include <asm/io.h>	/* for sync() */
+#else
+# define sync()		/* nothing */
+#endif
 
 /*
  * Check memory range for valid RAM. A simple memory test determines
@@ -38,20 +48,27 @@ long get_ram_size(volatile long *base, long maxsize)
 
 	for (cnt = (maxsize / sizeof (long)) >> 1; cnt > 0; cnt >>= 1) {
 		addr = base + cnt;	/* pointer arith! */
+		sync ();
 		save[i++] = *addr;
+		sync ();
 		*addr = ~cnt;
 	}
 
 	addr = base;
+	sync ();
 	save[i] = *addr;
+	sync ();
 	*addr = 0;
 
+	sync ();
 	if ((val = *addr) != 0) {
 		/* Restore the original data before leaving the function.
 		 */
+		sync ();
 		*addr = save[i];
 		for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) {
 			addr  = base + cnt;
+			sync ();
 			*addr = save[--i];
 		}
 		return (0);

include/common.h

@@ -270,7 +270,7 @@ int	misc_init_r   (void);
 void	jumptable_init(void);
 
 /* common/memsize.c */
-int	get_ram_size  (volatile long *, long);
+long	get_ram_size  (volatile long *, long);
 
 /* $(BOARD)/$(BOARD).c */
 void	reset_phy     (void);