MIPS: Loongson-3: Fast TLB refill handler

Loongson-3A R2 has pwbase/pwfield/pwsize/pwctl registers in CP0 (this
is very similar to HTW) and lwdir/lwpte/lddir/ldpte instructions which
can be used for fast TLB refill.

[ralf@linux-mips.org: Resolve conflict.]

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: Steven J . Hill <sjhill@realitydiluted.com>
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12754/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/uapi/asm/inst.h

@@ -203,6 +203,16 @@ enum mad_func {
 	nmadd_fp_op	= 0x0c, nmsub_fp_op	= 0x0e
 };
 
+/*
+ * func field for page table walker (Loongson-3).
+ */
+enum ptw_func {
+	lwdir_op = 0x00,
+	lwpte_op = 0x01,
+	lddir_op = 0x02,
+	ldpte_op = 0x03,
+};
+
 /*
  * func field for special3 lx opcodes (Cavium Octeon).
  */