powerpc/8xxx: Fix LAW init to respect pre-initialized entries

If some pre-boot or earlier stage bootloader (NAND SPL) has setup LAW
entries consider them good and mark them used.

In the NAND SPL case we skip re-initializing based on the law_table
since the SPL phase already did that.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

drivers/misc/fsl_law.c

@@ -24,6 +24,7 @@
  */
 
 #include <common.h>
+#include <linux/compiler.h>
 #include <asm/fsl_law.h>
 #include <asm/io.h>
 
@@ -246,6 +247,25 @@ void init_laws(void)
 #error FSL_HW_NUM_LAWS can not be greater than 32 w/o code changes
 #endif
 
+	/* 
+	 * Any LAWs that were set up before we booted assume they are meant to
+	 * be around and mark them used.
+	 */
+	for (i = 0; i < FSL_HW_NUM_LAWS; i++) {
+		u32 lawar = in_be32(LAWAR_ADDR(i));
+		
+		if (lawar & LAW_EN)
+			gd->used_laws |= (1 << i);
+	}
+
+#if defined(CONFIG_NAND_U_BOOT) && !defined(CONFIG_NAND_SPL)
+	/*
+	 * in NAND boot we've already parsed the law_table and setup those LAWs
+	 * so don't do it again.
+	 */
+	return;
+#endif
+
 	for (i = 0; i < num_law_entries; i++) {
 		if (law_table[i].index == -1)
 			set_next_law(law_table[i].addr, law_table[i].size,