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Diffstat (limited to 'kernel/arch/avr32/include/asm/atomic.h')
| -rw-r--r-- | kernel/arch/avr32/include/asm/atomic.h | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/kernel/arch/avr32/include/asm/atomic.h b/kernel/arch/avr32/include/asm/atomic.h new file mode 100644 index 000000000..2d07ce1c5 --- /dev/null +++ b/kernel/arch/avr32/include/asm/atomic.h @@ -0,0 +1,187 @@ +/* + * 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) + +#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 */ |