1 files changed, 115 insertions, 0 deletions
diff --git a/arch/mn10300/include/asm/div64.h b/arch/mn10300/include/asm/div64.h
new file mode 100644
index 000000000..503efab2a
--- /dev/null
+++ b/arch/mn10300/include/asm/div64.h
@@ -0,0 +1,115 @@
+/* MN10300 64-bit division
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#ifndef _ASM_DIV64
+#define _ASM_DIV64
+
+#include <linux/types.h>
+
+extern void ____unhandled_size_in_do_div___(void);
+
+/*
+ * Beginning with gcc 4.6, the MDR register is represented explicitly.  We
+ * must, therefore, at least explicitly clobber the register when we make
+ * changes to it.  The following assembly fragments *could* be rearranged in
+ * order to leave the moves to/from the MDR register to the compiler, but the
+ * gains would be minimal at best.
+ */
+#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
+# define CLOBBER_MDR_CC		"mdr", "cc"
+#else
+# define CLOBBER_MDR_CC		"cc"
+#endif
+
+/*
+ * divide n by base, leaving the result in n and returning the remainder
+ * - we can do this quite efficiently on the MN10300 by cascading the divides
+ *   through the MDR register
+ */
+#define do_div(n, base)							\
+({									\
+	unsigned __rem = 0;						\
+	if (sizeof(n) <= 4) {						\
+		asm("mov	%1,mdr	\n"				\
+		    "divu	%2,%0	\n"				\
+		    "mov	mdr,%1	\n"				\
+		    : "+r"(n), "=d"(__rem)				\
+		    : "r"(base), "1"(__rem)				\
+		    : CLOBBER_MDR_CC					\
+		    );							\
+	} else if (sizeof(n) <= 8) {					\
+		union {							\
+			unsigned long long l;				\
+			u32 w[2];					\
+		} __quot;						\
+		__quot.l = n;						\
+		asm("mov	%0,mdr	\n"	/* MDR = 0 */		\
+		    "divu	%3,%1	\n"				\
+		    /* __quot.MSL = __div.MSL / base, */		\
+		    /* MDR = MDR:__div.MSL % base */			\
+		    "divu	%3,%2	\n"				\
+		    /* __quot.LSL = MDR:__div.LSL / base, */		\
+		    /* MDR = MDR:__div.LSL % base */			\
+		    "mov	mdr,%0	\n"				\
+		    : "=d"(__rem), "=r"(__quot.w[1]), "=r"(__quot.w[0])	\
+		    : "r"(base), "0"(__rem), "1"(__quot.w[1]),		\
+		      "2"(__quot.w[0])					\
+		    : CLOBBER_MDR_CC					\
+		    );							\
+		n = __quot.l;						\
+	} else {							\
+		____unhandled_size_in_do_div___();			\
+	}								\
+	__rem;								\
+})
+
+/*
+ * do an unsigned 32-bit multiply and divide with intermediate 64-bit product
+ * so as not to lose accuracy
+ * - we use the MDR register to hold the MSW of the product
+ */
+static inline __attribute__((const))
+unsigned __muldiv64u(unsigned val, unsigned mult, unsigned div)
+{
+	unsigned result;
+
+	asm("mulu	%2,%0	\n"	/* MDR:val = val*mult */
+	    "divu	%3,%0	\n"	/* val = MDR:val/div;
+					 * MDR = MDR:val%div */
+	    : "=r"(result)
+	    : "0"(val), "ir"(mult), "r"(div)
+	    : CLOBBER_MDR_CC
+	    );
+
+	return result;
+}
+
+/*
+ * do a signed 32-bit multiply and divide with intermediate 64-bit product so
+ * as not to lose accuracy
+ * - we use the MDR register to hold the MSW of the product
+ */
+static inline __attribute__((const))
+signed __muldiv64s(signed val, signed mult, signed div)
+{
+	signed result;
+
+	asm("mul	%2,%0	\n"	/* MDR:val = val*mult */
+	    "div	%3,%0	\n"	/* val = MDR:val/div;
+					 * MDR = MDR:val%div */
+	    : "=r"(result)
+	    : "0"(val), "ir"(mult), "r"(div)
+	    : CLOBBER_MDR_CC
+	    );
+
+	return result;
+}
+
+#endif /* _ASM_DIV64 */