ARC: Atomic/bitops/cmpxchg/barriers

This covers the UP / SMP (with no hardware assist for atomic r-m-w) as
well as ARC700 LLOCK/SCOND insns based.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/atomic.h

@@ -0,0 +1,232 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _ASM_ARC_ATOMIC_H
+#define _ASM_ARC_ATOMIC_H
+
+#ifdef __KERNEL__
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+#include <linux/compiler.h>
+#include <asm/cmpxchg.h>
+#include <asm/barrier.h>
+#include <asm/smp.h>
+
+#define atomic_read(v)  ((v)->counter)
+
+#ifdef CONFIG_ARC_HAS_LLSC
+
+#define atomic_set(v, i) (((v)->counter) = (i))
+
+static inline void atomic_add(int i, atomic_t *v)
+{
+	unsigned int temp;
+
+	__asm__ __volatile__(
+	"1:	llock   %0, [%1]	\n"
+	"	add     %0, %0, %2	\n"
+	"	scond   %0, [%1]	\n"
+	"	bnz     1b		\n"
+	: "=&r"(temp)	/* Early clobber, to prevent reg reuse */
+	: "r"(&v->counter), "ir"(i)
+	: "cc");
+}
+
+static inline void atomic_sub(int i, atomic_t *v)
+{
+	unsigned int temp;
+
+	__asm__ __volatile__(
+	"1:	llock   %0, [%1]	\n"
+	"	sub     %0, %0, %2	\n"
+	"	scond   %0, [%1]	\n"
+	"	bnz     1b		\n"
+	: "=&r"(temp)
+	: "r"(&v->counter), "ir"(i)
+	: "cc");
+}
+
+/* add and also return the new value */
+static inline int atomic_add_return(int i, atomic_t *v)
+{
+	unsigned int temp;
+
+	__asm__ __volatile__(
+	"1:	llock   %0, [%1]	\n"
+	"	add     %0, %0, %2	\n"
+	"	scond   %0, [%1]	\n"
+	"	bnz     1b		\n"
+	: "=&r"(temp)
+	: "r"(&v->counter), "ir"(i)
+	: "cc");
+
+	return temp;
+}
+
+static inline int atomic_sub_return(int i, atomic_t *v)
+{
+	unsigned int temp;
+
+	__asm__ __volatile__(
+	"1:	llock   %0, [%1]	\n"
+	"	sub     %0, %0, %2	\n"
+	"	scond   %0, [%1]	\n"
+	"	bnz     1b		\n"
+	: "=&r"(temp)
+	: "r"(&v->counter), "ir"(i)
+	: "cc");
+
+	return temp;
+}
+
+static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
+{
+	unsigned int temp;
+
+	__asm__ __volatile__(
+	"1:	llock   %0, [%1]	\n"
+	"	bic     %0, %0, %2	\n"
+	"	scond   %0, [%1]	\n"
+	"	bnz     1b		\n"
+	: "=&r"(temp)
+	: "r"(addr), "ir"(mask)
+	: "cc");
+}
+
+#else	/* !CONFIG_ARC_HAS_LLSC */
+
+#ifndef CONFIG_SMP
+
+ /* violating atomic_xxx API locking protocol in UP for optimization sake */
+#define atomic_set(v, i) (((v)->counter) = (i))
+
+#else
+
+static inline void atomic_set(atomic_t *v, int i)
+{
+	/*
+	 * Independent of hardware support, all of the atomic_xxx() APIs need
+	 * to follow the same locking rules to make sure that a "hardware"
+	 * atomic insn (e.g. LD) doesn't clobber an "emulated" atomic insn
+	 * sequence
+	 *
+	 * Thus atomic_set() despite being 1 insn (and seemingly atomic)
+	 * requires the locking.
+	 */
+	unsigned long flags;
+
+	atomic_ops_lock(flags);
+	v->counter = i;
+	atomic_ops_unlock(flags);
+}
+#endif
+
+/*
+ * Non hardware assisted Atomic-R-M-W
+ * Locking would change to irq-disabling only (UP) and spinlocks (SMP)
+ */
+
+static inline void atomic_add(int i, atomic_t *v)
+{
+	unsigned long flags;
+
+	atomic_ops_lock(flags);
+	v->counter += i;
+	atomic_ops_unlock(flags);
+}
+
+static inline void atomic_sub(int i, atomic_t *v)
+{
+	unsigned long flags;
+
+	atomic_ops_lock(flags);
+	v->counter -= i;
+	atomic_ops_unlock(flags);
+}
+
+static inline int atomic_add_return(int i, atomic_t *v)
+{
+	unsigned long flags;
+	unsigned long temp;
+
+	atomic_ops_lock(flags);
+	temp = v->counter;
+	temp += i;
+	v->counter = temp;
+	atomic_ops_unlock(flags);
+
+	return temp;
+}
+
+static inline int atomic_sub_return(int i, atomic_t *v)
+{
+	unsigned long flags;
+	unsigned long temp;
+
+	atomic_ops_lock(flags);
+	temp = v->counter;
+	temp -= i;
+	v->counter = temp;
+	atomic_ops_unlock(flags);
+
+	return temp;
+}
+
+static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
+{
+	unsigned long flags;
+
+	atomic_ops_lock(flags);
+	*addr &= ~mask;
+	atomic_ops_unlock(flags);
+}
+
+#endif /* !CONFIG_ARC_HAS_LLSC */
+
+/**
+ * __atomic_add_unless - add unless the number is a given value
+ * @v: pointer of type atomic_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns the old value of @v
+ */
+#define __atomic_add_unless(v, a, u)					\
+({									\
+	int c, old;							\
+	c = atomic_read(v);						\
+	while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c)\
+		c = old;						\
+	c;								\
+})
+
+#define atomic_inc_not_zero(v)		atomic_add_unless((v), 1, 0)
+
+#define atomic_inc(v)			atomic_add(1, v)
+#define atomic_dec(v)			atomic_sub(1, v)
+
+#define atomic_inc_and_test(v)		(atomic_add_return(1, v) == 0)
+#define atomic_dec_and_test(v)		(atomic_sub_return(1, v) == 0)
+#define atomic_inc_return(v)		atomic_add_return(1, (v))
+#define atomic_dec_return(v)		atomic_sub_return(1, (v))
+#define atomic_sub_and_test(i, v)	(atomic_sub_return(i, v) == 0)
+
+#define atomic_add_negative(i, v)	(atomic_add_return(i, v) < 0)
+
+#define ATOMIC_INIT(i)			{ (i) }
+
+#include <asm-generic/atomic64.h>
+
+#endif
+
+#endif
+
+#endif

arch/arc/include/asm/barrier.h

@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __ASM_BARRIER_H
+#define __ASM_BARRIER_H
+
+#ifndef __ASSEMBLY__
+
+/* TODO-vineetg: Need to see what this does, don't we need sync anywhere */
+#define mb() __asm__ __volatile__ ("" : : : "memory")
+#define rmb() mb()
+#define wmb() mb()
+#define set_mb(var, value)  do { var = value; mb(); } while (0)
+#define set_wmb(var, value) do { var = value; wmb(); } while (0)
+#define read_barrier_depends()  mb()
+
+/* TODO-vineetg verify the correctness of macros here */
+#ifdef CONFIG_SMP
+#define smp_mb()        mb()
+#define smp_rmb()       rmb()
+#define smp_wmb()       wmb()
+#else
+#define smp_mb()        barrier()
+#define smp_rmb()       barrier()
+#define smp_wmb()       barrier()
+#endif
+
+#define smp_mb__before_atomic_dec()	barrier()
+#define smp_mb__after_atomic_dec()	barrier()
+#define smp_mb__before_atomic_inc()	barrier()
+#define smp_mb__after_atomic_inc()	barrier()
+
+#define smp_read_barrier_depends()      do { } while (0)
+
+#endif
+
+#endif