nds32: Support FP emulation

The Andes FPU coprocessor does not support denormalized number handling.
According to the specification, FPU generates a denorm input exception
that requires the kernel to deal with this instrution operation when it
encounters denormalized operands. Hence an nds32 FPU ISA emulator in the
kernel is required to meet requirement.

Signed-off-by: Vincent Chen <vincentc@andestech.com>
Signed-off-by: Nickhu <nickhu@andestech.com>
Acked-by: Greentime Hu <greentime@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/arch/nds32/math-emu/fd2s.c b/arch/nds32/math-emu/fd2s.c
new file mode 100644
index 000000000000..1328371e8170
--- /dev/null
+++ b/arch/nds32/math-emu/fd2s.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2018 Andes Technology Corporation
+#include <linux/uaccess.h>
+
+#include <asm/sfp-machine.h>
+#include <math-emu/double.h>
+#include <math-emu/single.h>
+#include <math-emu/soft-fp.h>
+void fd2s(void *ft, void *fa)
+{
+	FP_DECL_D(A);
+	FP_DECL_S(R);
+	FP_DECL_EX;
+
+	FP_UNPACK_DP(A, fa);
+
+	FP_CONV(S, D, 1, 2, R, A);
+
+	FP_PACK_SP(ft, R);
+
+	__FPU_FPCSR |= FP_CUR_EXCEPTIONS;
+}