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/*
* 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 <linux/types.h>
#include <asm/cmpxchg.h>
#define ATOMIC_INIT(i) { (i) }
#define atomic_read(v) ACCESS_ONCE((v)->counter)
#define atomic_set(v, i) (((v)->counter) = i)
#define ATOMIC_OP_RETURN(op, asm_op, asm_con) \
static inline int __atomic_##op##_return(int i, atomic_t *v) \
{ \
int result; \
\
asm volatile( \
"/* atomic_" #op "_return */\n" \
"1: ssrf 5\n" \
" ld.w %0, %2\n" \
" " #asm_op " %0, %3\n" \
" stcond %1, %0\n" \
" brne 1b" \
: "=&r" (result), "=o" (v->counter) \
: "m" (v->counter), #asm_con (i) \
: "cc"); \
\
return result; \
}
ATOMIC_OP_RETURN(sub, sub, rKs21)
ATOMIC_OP_RETURN(add, add, r)
#define ATOMIC_OP(op, asm_op) \
ATOMIC_OP_RETURN(op, asm_op, r) \
static inline void atomic_##op(int i, atomic_t *v) \
{ \
(void)__atomic_##op##_return(i, v); \
}
ATOMIC_OP(and, and)
ATOMIC_OP(or, or)
ATOMIC_OP(xor, eor)
#undef ATOMIC_OP
#undef ATOMIC_OP_RETURN
/*
* Probably found the reason why we want to use sub with the signed 21-bit
* limit, it uses one less register than the add instruction that can add up to
* 32-bit values.
*
* Both instructions are 32-bit, to use a 16-bit instruction the immediate is
* very small; 4 bit.
*
* sub 32-bit, type IV, takes a register and subtracts a 21-bit immediate.
* add 32-bit, type II, adds two register values together.
*/
#define IS_21BIT_CONST(i) \
(__builtin_constant_p(i) && ((i) >= -1048575) && ((i) <= 1048576))
/*
* 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)
{
if (IS_21BIT_CONST(i))
return __atomic_sub_return(-i, v);
return __atomic_add_return(i, v);
}
/*
* 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)
{
if (IS_21BIT_CONST(i))
return __atomic_sub_return(i, v);
return __atomic_add_return(-i, v);
}
/*
* __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 tmp, old = atomic_read(v);
if (IS_21BIT_CONST(a)) {
asm volatile(
"/* __atomic_sub_unless */\n"
"1: ssrf 5\n"
" ld.w %0, %2\n"
" cp.w %0, %4\n"
" breq 1f\n"
" sub %0, %3\n"
" stcond %1, %0\n"
" brne 1b\n"
"1:"
: "=&r"(tmp), "=o"(v->counter)
: "m"(v->counter), "rKs21"(-a), "rKs21"(u)
: "cc", "memory");
} else {
asm volatile(
"/* __atomic_add_unless */\n"
"1: ssrf 5\n"
" ld.w %0, %2\n"
" cp.w %0, %4\n"
" breq 1f\n"
" add %0, %3\n"
" stcond %1, %0\n"
" brne 1b\n"
"1:"
: "=&r"(tmp), "=o"(v->counter)
: "m"(v->counter), "r"(a), "ir"(u)
: "cc", "memory");
}
return old;
}
#undef IS_21BIT_CONST
/*
* 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) (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_dec_if_positive(v) atomic_sub_if_positive(1, v)
#endif /* __ASM_AVR32_ATOMIC_H */
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