/* * include/asm-xtensa/atomic.h * * Atomic operations that C can't guarantee us. Useful for resource counting.. * * 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) 2001 - 2008 Tensilica Inc. */ #ifndef _XTENSA_ATOMIC_H #define _XTENSA_ATOMIC_H #include #include #ifdef __KERNEL__ #include #include #include #define ATOMIC_INIT(i) { (i) } /* * This Xtensa implementation assumes that the right mechanism * for exclusion is for locking interrupts to level EXCM_LEVEL. * * Locking interrupts looks like this: * * rsil a15, TOPLEVEL * * wsr a15, PS * rsync * * Note that a15 is used here because the register allocation * done by the compiler is not guaranteed and a window overflow * may not occur between the rsil and wsr instructions. By using * a15 in the rsil, the machine is guaranteed to be in a state * where no register reference will cause an overflow. */ /** * 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)) #if XCHAL_HAVE_S32C1I #define ATOMIC_OP(op) \ static inline void atomic_##op(int i, atomic_t * v) \ { \ unsigned long tmp; \ int result; \ \ __asm__ __volatile__( \ "1: l32i %1, %3, 0\n" \ " wsr %1, scompare1\n" \ " " #op " %0, %1, %2\n" \ " s32c1i %0, %3, 0\n" \ " bne %0, %1, 1b\n" \ : "=&a" (result), "=&a" (tmp) \ : "a" (i), "a" (v) \ : "memory" \ ); \ } \ #define ATOMIC_OP_RETURN(op) \ static inline int atomic_##op##_return(int i, atomic_t * v) \ { \ unsigned long tmp; \ int result; \ \ __asm__ __volatile__( \ "1: l32i %1, %3, 0\n" \ " wsr %1, scompare1\n" \ " " #op " %0, %1, %2\n" \ " s32c1i %0, %3, 0\n" \ " bne %0, %1, 1b\n" \ " " #op " %0, %0, %2\n" \ : "=&a" (result), "=&a" (tmp) \ : "a" (i), "a" (v) \ : "memory" \ ); \ \ return result; \ } #define ATOMIC_FETCH_OP(op) \ static inline int atomic_fetch_##op(int i, atomic_t * v) \ { \ unsigned long tmp; \ int result; \ \ __asm__ __volatile__( \ "1: l32i %1, %3, 0\n" \ " wsr %1, scompare1\n" \ " " #op " %0, %1, %2\n" \ " s32c1i %0, %3, 0\n" \ " bne %0, %1, 1b\n" \ : "=&a" (result), "=&a" (tmp) \ : "a" (i), "a" (v) \ : "memory" \ ); \ \ return result; \ } #else /* XCHAL_HAVE_S32C1I */ #define ATOMIC_OP(op) \ static inline void atomic_##op(int i, atomic_t * v) \ { \ unsigned int vval; \ \ __asm__ __volatile__( \ " rsil a15, "__stringify(TOPLEVEL)"\n"\ " l32i %0, %2, 0\n" \ " " #op " %0, %0, %1\n" \ " s32i %0, %2, 0\n" \ " wsr a15, ps\n" \ " rsync\n" \ : "=&a" (vval) \ : "a" (i), "a" (v) \ : "a15", "memory" \ ); \ } \ #define ATOMIC_OP_RETURN(op) \ static inline int atomic_##op##_return(int i, atomic_t * v) \ { \ unsigned int vval; \ \ __asm__ __volatile__( \ " rsil a15,"__stringify(TOPLEVEL)"\n" \ " l32i %0, %2, 0\n" \ " " #op " %0, %0, %1\n" \ " s32i %0, %2, 0\n" \ " wsr a15, ps\n" \ " rsync\n" \ : "=&a" (vval) \ : "a" (i), "a" (v) \ : "a15", "memory" \ ); \ \ return vval; \ } #define ATOMIC_FETCH_OP(op) \ static inline int atomic_fetch_##op(int i, atomic_t * v) \ { \ unsigned int tmp, vval; \ \ __asm__ __volatile__( \ " rsil a15,"__stringify(TOPLEVEL)"\n" \ " l32i %0, %3, 0\n" \ " " #op " %1, %0, %2\n" \ " s32i %1, %3, 0\n" \ " wsr a15, ps\n" \ " rsync\n" \ : "=&a" (vval), "=&a" (tmp) \ : "a" (i), "a" (v) \ : "a15", "memory" \ ); \ \ return vval; \ } #endif /* XCHAL_HAVE_S32C1I */ #define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op) ATOMIC_OP_RETURN(op) ATOMIC_OPS(add) ATOMIC_OPS(sub) #undef ATOMIC_OPS #define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op) ATOMIC_OPS(and) ATOMIC_OPS(or) ATOMIC_OPS(xor) #undef ATOMIC_OPS #undef ATOMIC_FETCH_OP #undef ATOMIC_OP_RETURN #undef ATOMIC_OP /** * 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 - increment atomic variable * @v: pointer of type atomic_t * * Atomically increments @v by 1. */ #define atomic_inc(v) atomic_add(1,(v)) /** * atomic_inc - increment atomic variable * @v: pointer of type atomic_t * * Atomically increments @v by 1. */ #define atomic_inc_return(v) atomic_add_return(1,(v)) /** * atomic_dec - decrement atomic variable * @v: pointer of type atomic_t * * Atomically decrements @v by 1. */ #define atomic_dec(v) atomic_sub(1,(v)) /** * atomic_dec_return - decrement atomic variable * @v: pointer of type atomic_t * * Atomically decrements @v by 1. */ #define atomic_dec_return(v) atomic_sub_return(1,(v)) /** * atomic_dec_and_test - decrement 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_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_add_return(1,(v)) == 0) /** * 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) #define atomic_cmpxchg(v, o, n) ((int)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; } #endif /* __KERNEL__ */ #endif /* _XTENSA_ATOMIC_H */