/* * 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 - 2005 Tensilica Inc. */ #ifndef _XTENSA_ATOMIC_H #define _XTENSA_ATOMIC_H #include <linux/stringify.h> typedef struct { volatile int counter; } atomic_t; #ifdef __KERNEL__ #include <asm/processor.h> #include <asm/system.h> #define ATOMIC_INIT(i) { (i) } /* * This Xtensa implementation assumes that the right mechanism * for exclusion is for locking interrupts to level 1. * * Locking interrupts looks like this: * * rsil a15, 1 * <code> * 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) ((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) ((v)->counter = (i)) /** * atomic_add - add integer to atomic variable * @i: integer value to add * @v: pointer of type atomic_t * * Atomically adds @i to @v. */ static inline void atomic_add(int i, atomic_t * v) { unsigned int vval; __asm__ __volatile__( "rsil a15, "__stringify(LOCKLEVEL)"\n\t" "l32i %0, %2, 0 \n\t" "add %0, %0, %1 \n\t" "s32i %0, %2, 0 \n\t" "wsr a15, "__stringify(PS)" \n\t" "rsync \n" : "=&a" (vval) : "a" (i), "a" (v) : "a15", "memory" ); } /** * atomic_sub - subtract the atomic variable * @i: integer value to subtract * @v: pointer of type atomic_t * * Atomically subtracts @i from @v. */ static inline void atomic_sub(int i, atomic_t *v) { unsigned int vval; __asm__ __volatile__( "rsil a15, "__stringify(LOCKLEVEL)"\n\t" "l32i %0, %2, 0 \n\t" "sub %0, %0, %1 \n\t" "s32i %0, %2, 0 \n\t" "wsr a15, "__stringify(PS)" \n\t" "rsync \n" : "=&a" (vval) : "a" (i), "a" (v) : "a15", "memory" ); } /* * We use atomic_{add|sub}_return to define other functions. */ static inline int atomic_add_return(int i, atomic_t * v) { unsigned int vval; __asm__ __volatile__( "rsil a15,"__stringify(LOCKLEVEL)"\n\t" "l32i %0, %2, 0 \n\t" "add %0, %0, %1 \n\t" "s32i %0, %2, 0 \n\t" "wsr a15, "__stringify(PS)" \n\t" "rsync \n" : "=&a" (vval) : "a" (i), "a" (v) : "a15", "memory" ); return vval; } static inline int atomic_sub_return(int i, atomic_t * v) { unsigned int vval; __asm__ __volatile__( "rsil a15,"__stringify(LOCKLEVEL)"\n\t" "l32i %0, %2, 0 \n\t" "sub %0, %0, %1 \n\t" "s32i %0, %2, 0 \n\t" "wsr a15, "__stringify(PS)" \n\t" "rsync \n" : "=&a" (vval) : "a" (i), "a" (v) : "a15", "memory" ); return vval; } /** * 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 non-zero if @v was not @u, and zero otherwise. */ 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 != (u); } #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) static inline void atomic_clear_mask(unsigned int mask, atomic_t *v) { unsigned int all_f = -1; unsigned int vval; __asm__ __volatile__( "rsil a15,"__stringify(LOCKLEVEL)"\n\t" "l32i %0, %2, 0 \n\t" "xor %1, %4, %3 \n\t" "and %0, %0, %4 \n\t" "s32i %0, %2, 0 \n\t" "wsr a15, "__stringify(PS)" \n\t" "rsync \n" : "=&a" (vval), "=a" (mask) : "a" (v), "a" (all_f), "1" (mask) : "a15", "memory" ); } static inline void atomic_set_mask(unsigned int mask, atomic_t *v) { unsigned int vval; __asm__ __volatile__( "rsil a15,"__stringify(LOCKLEVEL)"\n\t" "l32i %0, %2, 0 \n\t" "or %0, %0, %1 \n\t" "s32i %0, %2, 0 \n\t" "wsr a15, "__stringify(PS)" \n\t" "rsync \n" : "=&a" (vval) : "a" (mask), "a" (v) : "a15", "memory" ); } /* Atomic operations are already serializing */ #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 /* __KERNEL__ */ #endif /* _XTENSA_ATOMIC_H */