/*
* Atomic operations that C can't guarantee us. Useful for
* resource counting etc.
*
* But use these as seldom as possible since they are slower than
* regular operations.
*
* Copyright (C) 2004-2006 Atmel Corporation
*
* 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_AVR32_ATOMIC_H
#define __ASM_AVR32_ATOMIC_H
#include <asm/system.h>
typedef struct { volatile int counter; } atomic_t;
#define ATOMIC_INIT(i) { (i) }
#define atomic_read(v) ((v)->counter)
#define atomic_set(v, i) (((v)->counter) = i)
/*
* atomic_sub_return - subtract the atomic variable
* @i: integer value to subtract
* @v: pointer of type atomic_t
*
* Atomically subtracts @i from @v. Returns the resulting value.
*/
static inline int atomic_sub_return(int i, atomic_t *v)
{
int result;
asm volatile(
"/* atomic_sub_return */\n"
"1: ssrf 5\n"
" ld.w %0, %2\n"
" sub %0, %3\n"
" stcond %1, %0\n"
" brne 1b"
: "=&r"(result), "=o"(v->counter)
: "m"(v->counter), "ir"(i)
: "cc");
return result;
}
/*
* atomic_add_return - add integer to atomic variable
* @i: integer value to add
* @v: pointer of type atomic_t
*
* Atomically adds @i to @v. Returns the resulting value.
*/
static inline int atomic_add_return(int i, atomic_t *v)
{
int result;
if (__builtin_constant_p(i))
result = atomic_sub_return(-i, v);
else
asm volatile(
"/* atomic_add_return */\n"
"1: ssrf 5\n"
" ld.w %0, %1\n"
" add %0, %3\n"
" stcond %2, %0\n"
" brne 1b"
: "=&r"(result), "=o"(v->counter)
: "m"(v->counter), "r"(i)
: "cc", "memory");
return result;
}
/*
* atomic_sub_unless - sub 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.
*
* If the atomic value v is not equal to u, this function subtracts a
* from v, and returns non zero. If v is equal to u then it returns
* zero. This is done as an atomic operation.
*/
static inline int atomic_sub_unless(atomic_t *v, int a, int u)
{
int tmp, result = 0;
asm volatile(
"/* atomic_sub_unless */\n"
"1: ssrf 5\n"
" ld.w %0, %3\n"
" cp.w %0, %5\n"
" breq 1f\n"
" sub %0, %4\n"
" stcond %2, %0\n"
" brne 1b\n"
" mov %1, 1\n"
"1:"
: "=&r"(tmp), "=&r"(result), "=o"(v->counter)
: "m"(v->counter), "ir"(a), "ir"(u)
: "cc", "memory");
return result;
}
/*
* 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.
*
* If the atomic value v is not equal to u, this function adds a to v,
* and returns non zero. If v is equal to u then it returns zero. This
* is done as an atomic operation.
*/
static inline int atomic_add_unless(atomic_t *v, int a, int u)
{
int tmp, result;
if (__builtin_constant_p(a))
result = atomic_sub_unless(v, -a, u);
else {
result = 0;
asm volatile(
"/* atomic_add_unless */\n"
"1: ssrf 5\n"
" ld.w %0, %3\n"
" cp.w %0, %5\n"
" breq 1f\n"
" add %0, %4\n"
" stcond %2, %0\n"
" brne 1b\n"
" mov %1, 1\n"
"1:"
: "=&r"(tmp), "=&r"(result), "=o"(v->counter)
: "m"(v->counter), "r"(a), "ir"(u)
: "cc", "memory");
}
return result;
}
/*
* 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;
asm volatile(
"/* atomic_sub_if_positive */\n"
"1: ssrf 5\n"
" ld.w %0, %2\n"
" sub %0, %3\n"
" brlt 1f\n"
" stcond %1, %0\n"
" brne 1b\n"
"1:"
: "=&r"(result), "=o"(v->counter)
: "m"(v->counter), "ir"(i)
: "cc", "memory");
return result;
}
#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
#define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
#define atomic_sub(i, v) (void)atomic_sub_return(i, v)
#define atomic_add(i, v) (void)atomic_add_return(i, v)
#define atomic_dec(v) atomic_sub(1, (v))
#define atomic_inc(v) atomic_add(1, (v))
#define atomic_dec_return(v) atomic_sub_return(1, v)
#define atomic_inc_return(v) atomic_add_return(1, v)
#define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)
#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_add_negative(i, v) (atomic_add_return(i, v) < 0)
#define atomic_inc_not_zero(v) atomic_add_unless(v, 1, 0)
#define atomic_dec_if_positive(v) atomic_sub_if_positive(1, v)
#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()
#include <asm-generic/atomic.h>
#endif /* __ASM_AVR32_ATOMIC_H */
