--- zzzz-none-000/linux-3.10.107/arch/powerpc/boot/dcr.h	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/arch/powerpc/boot/dcr.h	2021-02-04 17:41:59.000000000 +0000
@@ -15,6 +15,10 @@
 		asm volatile("mfdcrx %0,%1" : "=r"(rval) : "r"(rn)); \
 		rval; \
 	})
+#define mtdcrx(rn, val) \
+	({	\
+		asm volatile("mtdcrx %0,%1" : : "r"(rn), "r" (val)); \
+	})
 
 /* 440GP/440GX SDRAM controller DCRs */
 #define DCRN_SDRAM0_CFGADDR				0x010