MIPS: Add MAC2008 Support

MAC2008 means the processor implemented IEEE754 style Fused MADD
instruction. It was introduced in Release3 but removed in Release5.

The toolchain support of MAC2008 have never landed except for Loongson
processors.

This patch aimed to disabled the MAC2008 if it's optional. For
MAC2008 only processors, we corrected math-emu behavior to align
with actual hardware behavior.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
[paulburton@kernel.org: Fixup MIPSr2-r5 check in cpu_set_fpu_2008.]
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: chenhc@lemote.com
Cc: paul.burton@mips.com
Cc: linux-kernel@vger.kernel.org

1 files changed, 35 insertions, 18 deletions

diff --git a/arch/mips/math-emu/dp_maddf.c b/arch/mips/math-emu/dp_maddf.c
index 3da0ce44cdef..e24ef374d828 100644
--- a/arch/mips/math-emu/dp_maddf.c
+++ b/arch/mips/math-emu/dp_maddf.c
@@ -68,6 +68,12 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 
 	ieee754_clearcx();
 
+	rs = xs ^ ys;
+	if (flags & MADDF_NEGATE_PRODUCT)
+		rs ^= 1;
+	if (flags & MADDF_NEGATE_ADDITION)
+		zs ^= 1;
+
 	/*
 	 * Handle the cases when at least one of x, y or z is a NaN.
 	 * Order of precedence is sNaN, qNaN and z, x, y.
@@ -104,9 +110,7 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
-		if ((zc == IEEE754_CLASS_INF) &&
-		    ((!(flags & MADDF_NEGATE_PRODUCT) && (zs != (xs ^ ys))) ||
-		     ((flags & MADDF_NEGATE_PRODUCT) && (zs == (xs ^ ys))))) {
+		if ((zc == IEEE754_CLASS_INF) && (zs != rs)) {
 			/*
 			 * Cases of addition of infinities with opposite signs
 			 * or subtraction of infinities with same signs.
@@ -116,15 +120,10 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 		}
 		/*
 		 * z is here either not an infinity, or an infinity having the
-		 * same sign as product (x*y) (in case of MADDF.D instruction)
-		 * or product -(x*y) (in MSUBF.D case). The result must be an
-		 * infinity, and its sign is determined only by the value of
-		 * (flags & MADDF_NEGATE_PRODUCT) and the signs of x and y.
+		 * same sign as product (x*y). The result must be an infinity,
+		 * and its sign is determined only by the sign of product (x*y).
 		 */
-		if (flags & MADDF_NEGATE_PRODUCT)
-			return ieee754dp_inf(1 ^ (xs ^ ys));
-		else
-			return ieee754dp_inf(xs ^ ys);
+		return ieee754dp_inf(rs);
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
@@ -135,10 +134,7 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 			return ieee754dp_inf(zs);
 		if (zc == IEEE754_CLASS_ZERO) {
 			/* Handle cases +0 + (-0) and similar ones. */
-			if ((!(flags & MADDF_NEGATE_PRODUCT)
-					&& (zs == (xs ^ ys))) ||
-			    ((flags & MADDF_NEGATE_PRODUCT)
-					&& (zs != (xs ^ ys))))
+			if (zs == rs)
 				/*
 				 * Cases of addition of zeros of equal signs
 				 * or subtraction of zeroes of opposite signs.
@@ -187,9 +183,6 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 	assert(ym & DP_HIDDEN_BIT);
 
 	re = xe + ye;
-	rs = xs ^ ys;
-	if (flags & MADDF_NEGATE_PRODUCT)
-		rs ^= 1;
 
 	/* shunt to top of word */
 	xm <<= 64 - (DP_FBITS + 1);
@@ -340,3 +333,27 @@ union ieee754dp ieee754dp_msubf(union ieee754dp z, union ieee754dp x,
 {
 	return _dp_maddf(z, x, y, MADDF_NEGATE_PRODUCT);
 }
+
+union ieee754dp ieee754dp_madd(union ieee754dp z, union ieee754dp x,
+				union ieee754dp y)
+{
+	return _dp_maddf(z, x, y, 0);
+}
+
+union ieee754dp ieee754dp_msub(union ieee754dp z, union ieee754dp x,
+				union ieee754dp y)
+{
+	return _dp_maddf(z, x, y, MADDF_NEGATE_ADDITION);
+}
+
+union ieee754dp ieee754dp_nmadd(union ieee754dp z, union ieee754dp x,
+				union ieee754dp y)
+{
+	return _dp_maddf(z, x, y, MADDF_NEGATE_PRODUCT|MADDF_NEGATE_ADDITION);
+}
+
+union ieee754dp ieee754dp_nmsub(union ieee754dp z, union ieee754dp x,
+				union ieee754dp y)
+{
+	return _dp_maddf(z, x, y, MADDF_NEGATE_PRODUCT);
+}