metag: Atomics, locks and bitops

Add header files to implement Meta hardware thread locks (used by some
other atomic operations), atomics, spinlocks, and bitops.

There are 2 main types of atomic primitives for metag (in addition to
IRQs off on UP):
 - LOCK instructions provide locking between hardware threads.
 - LNKGET/LNKSET instructions provide load-linked/store-conditional
   operations allowing for lighter weight atomics on Meta2

LOCK instructions allow for hardware threads to acquire voluntary or
exclusive hardware thread locks:
 - LOCK0 releases exclusive and voluntary lock from the running hardware
   thread.
 - LOCK1 acquires the voluntary hardware lock, blocking until it becomes
   available.
 - LOCK2 implies LOCK1, and additionally acquires the exclusive hardware
   lock, blocking all other hardware threads from executing.

Signed-off-by: James Hogan <james.hogan@imgtec.com>

1 files changed, 234 insertions, 0 deletions

diff --git a/arch/metag/include/asm/atomic_lnkget.h b/arch/metag/include/asm/atomic_lnkget.h
new file mode 100644
index 0000000..d2e60a1
--- /dev/null
+++ b/arch/metag/include/asm/atomic_lnkget.h
@@ -0,0 +1,234 @@
+#ifndef __ASM_METAG_ATOMIC_LNKGET_H
+#define __ASM_METAG_ATOMIC_LNKGET_H
+
+#define ATOMIC_INIT(i)	{ (i) }
+
+#define atomic_set(v, i)		((v)->counter = (i))
+
+#include <linux/compiler.h>
+
+#include <asm/barrier.h>
+
+/*
+ * None of these asm statements clobber memory as LNKSET writes around
+ * the cache so the memory it modifies cannot safely be read by any means
+ * other than these accessors.
+ */
+
+static inline int atomic_read(const atomic_t *v)
+{
+	int temp;
+
+	asm volatile (
+		"LNKGETD %0, [%1]\n"
+		: "=da" (temp)
+		: "da" (&v->counter));
+
+	return temp;
+}
+
+static inline void atomic_add(int i, atomic_t *v)
+{
+	int temp;
+
+	asm volatile (
+		"1:	LNKGETD %0, [%1]\n"
+		"	ADD	%0, %0, %2\n"
+		"	LNKSETD [%1], %0\n"
+		"	DEFR	%0, TXSTAT\n"
+		"	ANDT	%0, %0, #HI(0x3f000000)\n"
+		"	CMPT	%0, #HI(0x02000000)\n"
+		"	BNZ	1b\n"
+		: "=&d" (temp)
+		: "da" (&v->counter), "bd" (i)
+		: "cc");
+}
+
+static inline void atomic_sub(int i, atomic_t *v)
+{
+	int temp;
+
+	asm volatile (
+		"1:	LNKGETD %0, [%1]\n"
+		"	SUB	%0, %0, %2\n"
+		"	LNKSETD [%1], %0\n"
+		"	DEFR	%0, TXSTAT\n"
+		"	ANDT	%0, %0, #HI(0x3f000000)\n"
+		"	CMPT	%0, #HI(0x02000000)\n"
+		"	BNZ 1b\n"
+		: "=&d" (temp)
+		: "da" (&v->counter), "bd" (i)
+		: "cc");
+}
+
+static inline int atomic_add_return(int i, atomic_t *v)
+{
+	int result, temp;
+
+	smp_mb();
+
+	asm volatile (
+		"1:	LNKGETD %1, [%2]\n"
+		"	ADD	%1, %1, %3\n"
+		"	LNKSETD [%2], %1\n"
+		"	DEFR	%0, TXSTAT\n"
+		"	ANDT	%0, %0, #HI(0x3f000000)\n"
+		"	CMPT	%0, #HI(0x02000000)\n"
+		"	BNZ 1b\n"
+		: "=&d" (temp), "=&da" (result)
+		: "da" (&v->counter), "bd" (i)
+		: "cc");
+
+	smp_mb();
+
+	return result;
+}
+
+static inline int atomic_sub_return(int i, atomic_t *v)
+{
+	int result, temp;
+
+	smp_mb();
+
+	asm volatile (
+		"1:	LNKGETD %1, [%2]\n"
+		"	SUB	%1, %1, %3\n"
+		"	LNKSETD [%2], %1\n"
+		"	DEFR	%0, TXSTAT\n"
+		"	ANDT	%0, %0, #HI(0x3f000000)\n"
+		"	CMPT	%0, #HI(0x02000000)\n"
+		"	BNZ	1b\n"
+		: "=&d" (temp), "=&da" (result)
+		: "da" (&v->counter), "bd" (i)
+		: "cc");
+
+	smp_mb();
+
+	return result;
+}
+
+static inline void atomic_clear_mask(unsigned int mask, atomic_t *v)
+{
+	int temp;
+
+	asm volatile (
+		"1:	LNKGETD %0, [%1]\n"
+		"	AND	%0, %0, %2\n"
+		"	LNKSETD	[%1] %0\n"
+		"	DEFR	%0, TXSTAT\n"
+		"	ANDT	%0, %0, #HI(0x3f000000)\n"
+		"	CMPT	%0, #HI(0x02000000)\n"
+		"	BNZ	1b\n"
+		: "=&d" (temp)
+		: "da" (&v->counter), "bd" (~mask)
+		: "cc");
+}
+
+static inline void atomic_set_mask(unsigned int mask, atomic_t *v)
+{
+	int temp;
+
+	asm volatile (
+		"1:	LNKGETD %0, [%1]\n"
+		"	OR	%0, %0, %2\n"
+		"	LNKSETD	[%1], %0\n"
+		"	DEFR	%0, TXSTAT\n"
+		"	ANDT	%0, %0, #HI(0x3f000000)\n"
+		"	CMPT	%0, #HI(0x02000000)\n"
+		"	BNZ	1b\n"
+		: "=&d" (temp)
+		: "da" (&v->counter), "bd" (mask)
+		: "cc");
+}
+
+static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
+{
+	int result, temp;
+
+	smp_mb();
+
+	asm volatile (
+		"1:	LNKGETD	%1, [%2]\n"
+		"	CMP	%1, %3\n"
+		"	LNKSETDEQ [%2], %4\n"
+		"	BNE	2f\n"
+		"	DEFR	%0, TXSTAT\n"
+		"	ANDT	%0, %0, #HI(0x3f000000)\n"
+		"	CMPT	%0, #HI(0x02000000)\n"
+		"	BNZ	1b\n"
+		"2:\n"
+		: "=&d" (temp), "=&d" (result)
+		: "da" (&v->counter), "bd" (old), "da" (new)
+		: "cc");
+
+	smp_mb();
+
+	return result;
+}
+
+static inline int atomic_xchg(atomic_t *v, int new)
+{
+	int temp, old;
+
+	asm volatile (
+		"1:	LNKGETD %1, [%2]\n"
+		"	LNKSETD	[%2], %3\n"
+		"	DEFR	%0, TXSTAT\n"
+		"	ANDT	%0, %0, #HI(0x3f000000)\n"
+		"	CMPT	%0, #HI(0x02000000)\n"
+		"	BNZ	1b\n"
+		: "=&d" (temp), "=&d" (old)
+		: "da" (&v->counter), "da" (new)
+		: "cc");
+
+	return old;
+}
+
+static inline int __atomic_add_unless(atomic_t *v, int a, int u)
+{
+	int result, temp;
+
+	smp_mb();
+
+	asm volatile (
+		"1:	LNKGETD %1, [%2]\n"
+		"	CMP	%1, %3\n"
+		"	ADD	%0, %1, %4\n"
+		"	LNKSETDNE [%2], %0\n"
+		"	BEQ	2f\n"
+		"	DEFR	%0, TXSTAT\n"
+		"	ANDT	%0, %0, #HI(0x3f000000)\n"
+		"	CMPT	%0, #HI(0x02000000)\n"
+		"	BNZ	1b\n"
+		"2:\n"
+		: "=&d" (temp), "=&d" (result)
+		: "da" (&v->counter), "bd" (u), "bd" (a)
+		: "cc");
+
+	smp_mb();
+
+	return result;
+}
+
+static inline int atomic_sub_if_positive(int i, atomic_t *v)
+{
+	int result, temp;
+
+	asm volatile (
+		"1:	LNKGETD %1, [%2]\n"
+		"	SUBS	%1, %1, %3\n"
+		"	LNKSETDGE [%2], %1\n"
+		"	BLT	2f\n"
+		"	DEFR	%0, TXSTAT\n"
+		"	ANDT	%0, %0, #HI(0x3f000000)\n"
+		"	CMPT	%0, #HI(0x02000000)\n"
+		"	BNZ	1b\n"
+		"2:\n"
+		: "=&d" (temp), "=&da" (result)
+		: "da" (&v->counter), "bd" (i)
+		: "cc");
+
+	return result;
+}
+
+#endif /* __ASM_METAG_ATOMIC_LNKGET_H */