FSL LAW: Add new interface to use the last free LAW

LAWs have the concept of priority so its useful to be able to allocate
the lowest (highest number) priority.  We will end up using this with the
new DDR code.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

drivers/misc/fsl_law.c

@@ -70,6 +70,25 @@ int set_next_law(phys_addr_t addr, enum law_size sz, enum law_trgt_if id)
 	return idx;
 }
 
+int set_last_law(phys_addr_t addr, enum law_size sz, enum law_trgt_if id)
+{
+	u32 idx;
+
+	/* we have no LAWs free */
+	if (gd->used_laws == -1)
+		return -1;
+
+	/* grab the last free law */
+	idx = __ilog2(~(gd->used_laws));
+
+	if (idx >= FSL_HW_NUM_LAWS)
+		return -1;
+
+	set_law(idx, addr, sz, id);
+
+	return idx;
+}
+
 void disable_law(u8 idx)
 {
 	volatile u32 *base = (volatile u32 *)(CFG_IMMR + 0xc08);

include/asm-ppc/fsl_law.h

@@ -74,6 +74,7 @@ struct law_entry {
 
 extern void set_law(u8 idx, phys_addr_t addr, enum law_size sz, enum law_trgt_if id);
 extern int set_next_law(phys_addr_t addr, enum law_size sz, enum law_trgt_if id);
+extern int set_last_law(phys_addr_t addr, enum law_size sz, enum law_trgt_if id);
 extern void disable_law(u8 idx);
 extern void init_laws(void);
 extern void print_laws(void);