add or1k (OpenRISC 1000) architecture port

With the exception of a fenv implementation, the port is fully featured.
The port has been tested in or1ksim, the golden reference functional
simulator for OpenRISC 1000.
It passes all libc-test tests (except the math tests that
requires a fenv implementation).

The port assumes an or1k implementation that has support for
atomic instructions (l.lwa/l.swa).

Although it passes all the libc-test tests, the port is still
in an experimental state, and has yet experienced very little
'real-world' use.

arch/or1k/atomic.h

@@ -0,0 +1,122 @@
+#ifndef _INTERNAL_ATOMIC_H
+#define _INTERNAL_ATOMIC_H
+
+#include <stdint.h>
+
+static inline int a_ctz_l(unsigned long x)
+{
+	static const char debruijn32[32] = {
+		0, 1, 23, 2, 29, 24, 19, 3, 30, 27, 25, 11, 20, 8, 4, 13,
+		31, 22, 28, 18, 26, 10, 7, 12, 21, 17, 9, 6, 16, 5, 15, 14
+	};
+	return debruijn32[(x&-x)*0x076be629 >> 27];
+}
+
+static inline int a_ctz_64(uint64_t x)
+{
+	uint32_t y = x;
+	if (!y) {
+		y = x>>32;
+		return 32 + a_ctz_l(y);
+	}
+	return a_ctz_l(y);
+}
+
+static inline int a_cas(volatile int *p, int t, int s)
+{
+	__asm__("1:	l.lwa %0, %1\n"
+		"	l.sfeq %0, %2\n"
+		"	l.bnf 1f\n"
+		"	 l.nop\n"
+		"	l.swa %1, %3\n"
+		"	l.bnf 1b\n"
+		"	 l.nop\n"
+		"1:	\n"
+		: "=&r"(t), "+m"(*p) : "r"(t), "r"(s) : "cc", "memory" );
+        return t;
+}
+
+static inline void *a_cas_p(volatile void *p, void *t, void *s)
+{
+	return (void *)a_cas(p, (int)t, (int)s);
+}
+
+static inline long a_cas_l(volatile void *p, long t, long s)
+{
+	return a_cas(p, t, s);
+}
+
+static inline int a_swap(volatile int *x, int v)
+{
+	int old;
+	do old = *x;
+	while (a_cas(x, old, v) != old);
+	return old;
+}
+
+static inline int a_fetch_add(volatile int *x, int v)
+{
+	int old;
+	do old = *x;
+	while (a_cas(x, old, old+v) != old);
+	return old;
+}
+
+static inline void a_inc(volatile int *x)
+{
+	a_fetch_add(x, 1);
+}
+
+static inline void a_dec(volatile int *x)
+{
+	a_fetch_add(x, -1);
+}
+
+static inline void a_store(volatile int *p, int x)
+{
+	*p=x;
+}
+
+static inline void a_spin()
+{
+}
+
+static inline void a_crash()
+{
+	*(volatile char *)0=0;
+}
+
+static inline void a_and(volatile int *p, int v)
+{
+	int old;
+	do old = *p;
+	while (a_cas(p, old, old&v) != old);
+}
+
+static inline void a_or(volatile int *p, int v)
+{
+	int old;
+	do old = *p;
+	while (a_cas(p, old, old|v) != old);
+}
+
+static inline void a_or_l(volatile void *p, long v)
+{
+	a_or(p, v);
+}
+
+static inline void a_and_64(volatile uint64_t *p, uint64_t v)
+{
+	union { uint64_t v; uint32_t r[2]; } u = { v };
+	a_and((int *)p, u.r[0]);
+	a_and((int *)p+1, u.r[1]);
+}
+
+static inline void a_or_64(volatile uint64_t *p, uint64_t v)
+{
+	union { uint64_t v; uint32_t r[2]; } u = { v };
+	a_or((int *)p, u.r[0]);
+	a_or((int *)p+1, u.r[1]);
+}
+
+#endif