atomic.h

/*
 * Atomic operations that C can't guarantee us.  Useful for
 * resource counting etc..
 *
 * But use these as seldom as possible since they are much more slower
 * than regular operations.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1996, 97, 99, 2000, 03, 04, 06 by Ralf Baechle
 */
#ifndef _ASM_ATOMIC_H
#define _ASM_ATOMIC_H

#include <linux/irqflags.h>
#include <linux/types.h>
#include <asm/barrier.h>
#include <asm/compiler.h>
#include <asm/cpu-features.h>
#include <asm/cmpxchg.h>
#include <asm/war.h>

#define ATOMIC_INIT(i)	  { (i) }

/*
 * atomic_read - read atomic variable
 * @v: pointer of type atomic_t
 *
 * Atomically reads the value of @v.
 */
#define atomic_read(v)		READ_ONCE((v)->counter)

/*
 * atomic_set - set atomic variable
 * @v: pointer of type atomic_t
 * @i: required value
 *
 * Atomically sets the value of @v to @i.
 */
#define atomic_set(v, i)	WRITE_ONCE((v)->counter, (i))

#define ATOMIC_OP(op, c_op, asm_op)					      \
static __inline__ void atomic_##op(int i, atomic_t * v)			      \
{									      \
	if (kernel_uses_llsc && R10000_LLSC_WAR) {			      \
		int temp;						      \
									      \
		__asm__ __volatile__(					      \
		"	.set	arch=r4000				\n"   \
		"1:	ll	%0, %1		# atomic_" #op "	\n"   \
		"	" #asm_op " %0, %2				\n"   \
		"	sc	%0, %1					\n"   \
		"	beqzl	%0, 1b					\n"   \
		"	.set	mips0					\n"   \
		: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (v->counter)	      \
		: "Ir" (i));						      \
	} else if (kernel_uses_llsc) {					      \
		int temp;						      \
									      \
		do {							      \
			__asm__ __volatile__(				      \
			"	.set	"MIPS_ISA_LEVEL"		\n"   \
			"	ll	%0, %1		# atomic_" #op "\n"   \
			"	" #asm_op " %0, %2			\n"   \
			"	sc	%0, %1				\n"   \
			"	.set	mips0				\n"   \
			: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (v->counter)      \
			: "Ir" (i));					      \
		} while (unlikely(!temp));				      \
	} else {							      \
		unsigned long flags;					      \
									      \
		raw_local_irq_save(flags);				      \
		v->counter c_op i;					      \
		raw_local_irq_restore(flags);				      \
	}								      \
}

#define ATOMIC_OP_RETURN(op, c_op, asm_op)				      \
static __inline__ int atomic_##op##_return(int i, atomic_t * v)		      \
{									      \
	int result;							      \
									      \
	smp_mb__before_llsc();						      \
									      \
	if (kernel_uses_llsc && R10000_LLSC_WAR) {			      \
		int temp;						      \
									      \
		__asm__ __volatile__(					      \
		"	.set	arch=r4000				\n"   \
		"1:	ll	%1, %2		# atomic_" #op "_return	\n"   \
		"	" #asm_op " %0, %1, %3				\n"   \
		"	sc	%0, %2					\n"   \
		"	beqzl	%0, 1b					\n"   \
		"	" #asm_op " %0, %1, %3				\n"   \
		"	.set	mips0					\n"   \
		: "=&r" (result), "=&r" (temp),				      \
		  "+" GCC_OFF_SMALL_ASM() (v->counter)			      \
		: "Ir" (i));						      \
	} else if (kernel_uses_llsc) {					      \
		int temp;						      \
									      \
		do {							      \
			__asm__ __volatile__(				      \
			"	.set	"MIPS_ISA_LEVEL"		\n"   \
			"	ll	%1, %2	# atomic_" #op "_return	\n"   \
			"	" #asm_op " %0, %1, %3			\n"   \
			"	sc	%0, %2				\n"   \
			"	.set	mips0				\n"   \
			: "=&r" (result), "=&r" (temp),			      \
			  "+" GCC_OFF_SMALL_ASM() (v->counter)		      \
			: "Ir" (i));					      \
		} while (unlikely(!result));				      \
									      \
		result = temp; result c_op i;				      \
	} else {							      \
		unsigned long flags;					      \
									      \
		raw_local_irq_save(flags);				      \
		result = v->counter;					      \
		result c_op i;						      \
		v->counter = result;					      \
		raw_local_irq_restore(flags);				      \
	}								      \
									      \
	smp_llsc_mb();							      \
									      \
	return result;							      \
}

#define ATOMIC_OPS(op, c_op, asm_op)					      \
	ATOMIC_OP(op, c_op, asm_op)					      \
	ATOMIC_OP_RETURN(op, c_op, asm_op)

ATOMIC_OPS(add, +=, addu)
ATOMIC_OPS(sub, -=, subu)

ATOMIC_OP(and, &=, and)
ATOMIC_OP(or, |=, or)
ATOMIC_OP(xor, ^=, xor)

#undef ATOMIC_OPS
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP

/*
 * atomic_sub_if_positive - conditionally subtract integer from atomic variable
 * @i: integer value to subtract
 * @v: pointer of type atomic_t
 *
 * Atomically test @v and subtract @i if @v is greater or equal than @i.
 * The function returns the old value of @v minus @i.
 */
static __inline__ int atomic_sub_if_positive(int i, atomic_t * v)
{
	int result;

	smp_mb__before_llsc();

	if (kernel_uses_llsc && R10000_LLSC_WAR) {
		int temp;

		__asm__ __volatile__(
		"	.set	arch=r4000				\n"
		"1:	ll	%1, %2		# atomic_sub_if_positive\n"
		"	subu	%0, %1, %3				\n"
		"	bltz	%0, 1f					\n"
		"	sc	%0, %2					\n"
		"	.set	noreorder				\n"
		"	beqzl	%0, 1b					\n"
		"	 subu	%0, %1, %3				\n"
		"	.set	reorder					\n"
		"1:							\n"
		"	.set	mips0					\n"
		: "=&r" (result), "=&r" (temp),
		  "+" GCC_OFF_SMALL_ASM() (v->counter)
		: "Ir" (i), GCC_OFF_SMALL_ASM() (v->counter)
		: "memory");
	} else if (kernel_uses_llsc) {
		int temp;

		__asm__ __volatile__(
		"	.set	"MIPS_ISA_LEVEL"			\n"
		"1:	ll	%1, %2		# atomic_sub_if_positive\n"
		"	subu	%0, %1, %3				\n"
		"	bltz	%0, 1f					\n"
		"	sc	%0, %2					\n"
		"	.set	noreorder				\n"
		"	beqz	%0, 1b					\n"
		"	 subu	%0, %1, %3				\n"
		"	.set	reorder					\n"
		"1:							\n"
		"	.set	mips0					\n"
		: "=&r" (result), "=&r" (temp),
		  "+" GCC_OFF_SMALL_ASM() (v->counter)
		: "Ir" (i));
	} else {
		unsigned long flags;

		raw_local_irq_save(flags);
		result = v->counter;
		result -= i;
		if (result >= 0)
			v->counter = result;
		raw_local_irq_restore(flags);
	}

	smp_llsc_mb();

	return result;
}

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

/**
 * __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.
 */
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;
}

#define atomic_dec_return(v) atomic_sub_return(1, (v))
#define atomic_inc_return(v) atomic_add_return(1, (v))

/*
 * atomic_sub_and_test - subtract value from variable and test result
 * @i: integer value to subtract
 * @v: pointer of type atomic_t
 *
 * Atomically subtracts @i from @v and returns
 * true if the result is zero, or false for all
 * other cases.
 */
#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)

/*
 * atomic_inc_and_test - increment and test
 * @v: pointer of type atomic_t
 *
 * Atomically increments @v by 1
 * and returns true if the result is zero, or false for all
 * other cases.
 */
#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)

/*
 * atomic_dec_and_test - decrement by 1 and test
 * @v: pointer of type atomic_t
 *
 * Atomically decrements @v by 1 and
 * returns true if the result is 0, or false for all other
 * cases.
 */
#define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0)

/*
 * atomic_dec_if_positive - decrement by 1 if old value positive
 * @v: pointer of type atomic_t
 */
#define atomic_dec_if_positive(v)	atomic_sub_if_positive(1, v)

/*
 * atomic_inc - increment atomic variable
 * @v: pointer of type atomic_t
 *
 * Atomically increments @v by 1.
 */
#define atomic_inc(v) atomic_add(1, (v))

/*
 * atomic_dec - decrement and test
 * @v: pointer of type atomic_t
 *
 * Atomically decrements @v by 1.
 */
#define atomic_dec(v) atomic_sub(1, (v))

/*
 * atomic_add_negative - add and test if negative
 * @v: pointer of type atomic_t
 * @i: integer value to add
 *
 * Atomically adds @i to @v and returns true
 * if the result is negative, or false when
 * result is greater than or equal to zero.
 */
#define atomic_add_negative(i, v) (atomic_add_return(i, (v)) < 0)

#ifdef CONFIG_64BIT

#define ATOMIC64_INIT(i)    { (i) }

/*
 * atomic64_read - read atomic variable
 * @v: pointer of type atomic64_t
 *
 */
#define atomic64_read(v)	READ_ONCE((v)->counter)

/*
 * atomic64_set - set atomic variable
 * @v: pointer of type atomic64_t
 * @i: required value
 */
#define atomic64_set(v, i)	WRITE_ONCE((v)->counter, (i))

#define ATOMIC64_OP(op, c_op, asm_op)					      \
static __inline__ void atomic64_##op(long i, atomic64_t * v)		      \
{									      \
	if (kernel_uses_llsc && R10000_LLSC_WAR) {			      \
		long temp;						      \
									      \
		__asm__ __volatile__(					      \
		"	.set	arch=r4000				\n"   \
		"1:	lld	%0, %1		# atomic64_" #op "	\n"   \
		"	" #asm_op " %0, %2				\n"   \
		"	scd	%0, %1					\n"   \
		"	beqzl	%0, 1b					\n"   \
		"	.set	mips0					\n"   \
		: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (v->counter)	      \
		: "Ir" (i));						      \
	} else if (kernel_uses_llsc) {					      \
		long temp;						      \
									      \
		do {							      \
			__asm__ __volatile__(				      \
			"	.set	"MIPS_ISA_LEVEL"		\n"   \
			"	lld	%0, %1		# atomic64_" #op "\n" \
			"	" #asm_op " %0, %2			\n"   \
			"	scd	%0, %1				\n"   \
			"	.set	mips0				\n"   \
			: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (v->counter)      \
			: "Ir" (i));					      \
		} while (unlikely(!temp));				      \
	} else {							      \
		unsigned long flags;					      \
									      \
		raw_local_irq_save(flags);				      \
		v->counter c_op i;					      \
		raw_local_irq_restore(flags);				      \
	}								      \
}

#define ATOMIC64_OP_RETURN(op, c_op, asm_op)				      \
static __inline__ long atomic64_##op##_return(long i, atomic64_t * v)	      \
{									      \
	long result;							      \
									      \
	smp_mb__before_llsc();						      \
									      \
	if (kernel_uses_llsc && R10000_LLSC_WAR) {			      \
		long temp;						      \
									      \
		__asm__ __volatile__(					      \
		"	.set	arch=r4000				\n"   \
		"1:	lld	%1, %2		# atomic64_" #op "_return\n"  \
		"	" #asm_op " %0, %1, %3				\n"   \
		"	scd	%0, %2					\n"   \
		"	beqzl	%0, 1b					\n"   \
		"	" #asm_op " %0, %1, %3				\n"   \
		"	.set	mips0					\n"   \
		: "=&r" (result), "=&r" (temp),				      \
		  "+" GCC_OFF_SMALL_ASM() (v->counter)			      \
		: "Ir" (i));						      \
	} else if (kernel_uses_llsc) {					      \
		long temp;						      \
									      \
		do {							      \
			__asm__ __volatile__(				      \
			"	.set	"MIPS_ISA_LEVEL"		\n"   \
			"	lld	%1, %2	# atomic64_" #op "_return\n"  \
			"	" #asm_op " %0, %1, %3			\n"   \
			"	scd	%0, %2				\n"   \
			"	.set	mips0				\n"   \
			: "=&r" (result), "=&r" (temp),			      \
			  "=" GCC_OFF_SMALL_ASM() (v->counter)		      \
			: "Ir" (i), GCC_OFF_SMALL_ASM() (v->counter)	      \
			: "memory");					      \
		} while (unlikely(!result));				      \
									      \
		result = temp; result c_op i;				      \
	} else {							      \
		unsigned long flags;					      \
									      \
		raw_local_irq_save(flags);				      \
		result = v->counter;					      \
		result c_op i;						      \
		v->counter = result;					      \
		raw_local_irq_restore(flags);				      \
	}								      \
									      \
	smp_llsc_mb();							      \
									      \
	return result;							      \
}

#define ATOMIC64_OPS(op, c_op, asm_op)					      \
	ATOMIC64_OP(op, c_op, asm_op)					      \
	ATOMIC64_OP_RETURN(op, c_op, asm_op)

ATOMIC64_OPS(add, +=, daddu)
ATOMIC64_OPS(sub, -=, dsubu)
ATOMIC64_OP(and, &=, and)
ATOMIC64_OP(or, |=, or)
ATOMIC64_OP(xor, ^=, xor)

#undef ATOMIC64_OPS
#undef ATOMIC64_OP_RETURN
#undef ATOMIC64_OP

/*
 * atomic64_sub_if_positive - conditionally subtract integer from atomic
 *                            variable
 * @i: integer value to subtract
 * @v: pointer of type atomic64_t
 *
 * Atomically test @v and subtract @i if @v is greater or equal than @i.
 * The function returns the old value of @v minus @i.
 */
static __inline__ long atomic64_sub_if_positive(long i, atomic64_t * v)
{
	long result;

	smp_mb__before_llsc();

	if (kernel_uses_llsc && R10000_LLSC_WAR) {
		long temp;

		__asm__ __volatile__(
		"	.set	arch=r4000				\n"
		"1:	lld	%1, %2		# atomic64_sub_if_positive\n"
		"	dsubu	%0, %1, %3				\n"
		"	bltz	%0, 1f					\n"
		"	scd	%0, %2					\n"
		"	.set	noreorder				\n"
		"	beqzl	%0, 1b					\n"
		"	 dsubu	%0, %1, %3				\n"
		"	.set	reorder					\n"
		"1:							\n"
		"	.set	mips0					\n"
		: "=&r" (result), "=&r" (temp),
		  "=" GCC_OFF_SMALL_ASM() (v->counter)
		: "Ir" (i), GCC_OFF_SMALL_ASM() (v->counter)
		: "memory");
	} else if (kernel_uses_llsc) {
		long temp;

		__asm__ __volatile__(
		"	.set	"MIPS_ISA_LEVEL"			\n"
		"1:	lld	%1, %2		# atomic64_sub_if_positive\n"
		"	dsubu	%0, %1, %3				\n"
		"	bltz	%0, 1f					\n"
		"	scd	%0, %2					\n"
		"	.set	noreorder				\n"
		"	beqz	%0, 1b					\n"
		"	 dsubu	%0, %1, %3				\n"
		"	.set	reorder					\n"
		"1:							\n"
		"	.set	mips0					\n"
		: "=&r" (result), "=&r" (temp),
		  "+" GCC_OFF_SMALL_ASM() (v->counter)
		: "Ir" (i));
	} else {
		unsigned long flags;

		raw_local_irq_save(flags);
		result = v->counter;
		result -= i;
		if (result >= 0)
			v->counter = result;
		raw_local_irq_restore(flags);
	}

	smp_llsc_mb();

	return result;
}

#define atomic64_cmpxchg(v, o, n) \
	((__typeof__((v)->counter))cmpxchg(&((v)->counter), (o), (n)))
#define atomic64_xchg(v, new) (xchg(&((v)->counter), (new)))

/**
 * atomic64_add_unless - add unless the number is a given value
 * @v: pointer of type atomic64_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 true iff @v was not @u.
 */
static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u)
{
	long c, old;
	c = atomic64_read(v);
	for (;;) {
		if (unlikely(c == (u)))
			break;
		old = atomic64_cmpxchg((v), c, c + (a));
		if (likely(old == c))
			break;
		c = old;
	}
	return c != (u);
}

#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)

#define atomic64_dec_return(v) atomic64_sub_return(1, (v))
#define atomic64_inc_return(v) atomic64_add_return(1, (v))

/*
 * atomic64_sub_and_test - subtract value from variable and test result
 * @i: integer value to subtract
 * @v: pointer of type atomic64_t
 *
 * Atomically subtracts @i from @v and returns
 * true if the result is zero, or false for all
 * other cases.
 */
#define atomic64_sub_and_test(i, v) (atomic64_sub_return((i), (v)) == 0)

/*
 * atomic64_inc_and_test - increment and test
 * @v: pointer of type atomic64_t
 *
 * Atomically increments @v by 1
 * and returns true if the result is zero, or false for all
 * other cases.
 */
#define atomic64_inc_and_test(v) (atomic64_inc_return(v) == 0)

/*
 * atomic64_dec_and_test - decrement by 1 and test
 * @v: pointer of type atomic64_t
 *
 * Atomically decrements @v by 1 and
 * returns true if the result is 0, or false for all other
 * cases.
 */
#define atomic64_dec_and_test(v) (atomic64_sub_return(1, (v)) == 0)

/*
 * atomic64_dec_if_positive - decrement by 1 if old value positive
 * @v: pointer of type atomic64_t
 */
#define atomic64_dec_if_positive(v)	atomic64_sub_if_positive(1, v)

/*
 * atomic64_inc - increment atomic variable
 * @v: pointer of type atomic64_t
 *
 * Atomically increments @v by 1.
 */
#define atomic64_inc(v) atomic64_add(1, (v))

/*
 * atomic64_dec - decrement and test
 * @v: pointer of type atomic64_t
 *
 * Atomically decrements @v by 1.
 */
#define atomic64_dec(v) atomic64_sub(1, (v))

/*
 * atomic64_add_negative - add and test if negative
 * @v: pointer of type atomic64_t
 * @i: integer value to add
 *
 * Atomically adds @i to @v and returns true
 * if the result is negative, or false when
 * result is greater than or equal to zero.
 */
#define atomic64_add_negative(i, v) (atomic64_add_return(i, (v)) < 0)

#endif /* CONFIG_64BIT */

#endif /* _ASM_ATOMIC_H */