arch/sh/include/asm/atomic-llsc.h

#ifndef __ASM_SH_ATOMIC_LLSC_H
#define __ASM_SH_ATOMIC_LLSC_H

/*
 * To get proper branch prediction for the main line, we must branch
 * forward to code at the end of this object's .text section, then
 * branch back to restart the operation.
 */
static inline void atomic_add(int i, atomic_t *v)
{
	unsigned long tmp;

	__asm__ __volatile__ (
"1:	movli.l @%2, %0		! atomic_add	\n"
"	add	%1, %0				\n"
"	movco.l	%0, @%2				\n"
"	bf	1b				\n"
	: "=&z" (tmp)
	: "r" (i), "r" (&v->counter)
	: "t");
}

static inline void atomic_sub(int i, atomic_t *v)
{
	unsigned long tmp;

	__asm__ __volatile__ (
"1:	movli.l @%2, %0		! atomic_sub	\n"
"	sub	%1, %0				\n"
"	movco.l	%0, @%2				\n"
"	bf	1b				\n"
	: "=&z" (tmp)
	: "r" (i), "r" (&v->counter)
	: "t");
}

/*
 * SH-4A note:
 *
 * We basically get atomic_xxx_return() for free compared with
 * atomic_xxx(). movli.l/movco.l require r0 due to the instruction
 * encoding, so the retval is automatically set without having to
 * do any special work.
 */
static inline int atomic_add_return(int i, atomic_t *v)
{
	unsigned long temp;

	__asm__ __volatile__ (
"1:	movli.l @%2, %0		! atomic_add_return	\n"
"	add	%1, %0					\n"
"	movco.l	%0, @%2					\n"
"	bf	1b					\n"
"	synco						\n"
	: "=&z" (temp)
	: "r" (i), "r" (&v->counter)
	: "t");

	return temp;
}

static inline int atomic_sub_return(int i, atomic_t *v)
{
	unsigned long temp;

	__asm__ __volatile__ (
"1:	movli.l @%2, %0		! atomic_sub_return	\n"
"	sub	%1, %0					\n"
"	movco.l	%0, @%2					\n"
"	bf	1b					\n"
"	synco						\n"
	: "=&z" (temp)
	: "r" (i), "r" (&v->counter)
	: "t");

	return temp;
}

static inline void atomic_clear_mask(unsigned int mask, atomic_t *v)
{
	unsigned long tmp;

	__asm__ __volatile__ (
"1:	movli.l @%2, %0		! atomic_clear_mask	\n"
"	and	%1, %0					\n"
"	movco.l	%0, @%2					\n"
"	bf	1b					\n"
	: "=&z" (tmp)
	: "r" (~mask), "r" (&v->counter)
	: "t");
}

static inline void atomic_set_mask(unsigned int mask, atomic_t *v)
{
	unsigned long tmp;

	__asm__ __volatile__ (
"1:	movli.l @%2, %0		! atomic_set_mask	\n"
"	or	%1, %0					\n"
"	movco.l	%0, @%2					\n"
"	bf	1b					\n"
	: "=&z" (tmp)
	: "r" (mask), "r" (&v->counter)
	: "t");
}

#define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))

/**
 * 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 non-zero if @v was not @u, and zero otherwise.
 */
static inline int atomic_add_unless(atomic_t *v, int a, int u)
{
	int c, old;
	c = atomic_read(v);
	for (;;) {
		if (unlikely(c == (u)))
			break;
		old = atomic_cmpxchg((v), c, c + (a));
		if (likely(old == c))
			break;
		c = old;
	}

	return c != (u);
}

#endif /* __ASM_SH_ATOMIC_LLSC_H */