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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 much more slower

 * than regular operations.

 *

 * 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) 1996, 1997, 2000 by Ralf Baechle

 */

#ifndef __ASM_ATOMIC_H

#define __ASM_ATOMIC_H

#include <linux/config.h>

typedef struct { volatile int counter; } atomic_t;

#ifdef __KERNEL__

#define ATOMIC_INIT(i)    { (i) }

/*

 * atomic_read - read atomic variable

 * @v: pointer of type atomic_t

 *

 * Atomically reads the value of @v.  Note that the guaranteed

 * useful range of an atomic_t is only 24 bits.

 */

#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.  Note that the guaranteed

 * useful range of an atomic_t is only 24 bits.

 */

#define atomic_set(v,i) ((v)->counter = (i))

#ifndef CONFIG_CPU_HAS_LLSC

#include <asm/system.h>

/*

 * The MIPS I implementation is only atomic with respect to

 * interrupts.  R3000 based multiprocessor machines are rare anyway ...

 *

 * atomic_add - add integer to atomic variable

 * @i: integer value to add

 * @v: pointer of type atomic_t

 *

 * Atomically adds @i to @v.  Note that the guaranteed useful range

 * of an atomic_t is only 24 bits.

 */

static __inline__ void atomic_add(int i, atomic_t * v)

{

        unsigned long flags;

        local_irq_save(flags);

        v->counter += i;

        local_irq_restore(flags);

}

/*

 * atomic_sub - subtract the atomic variable

 * @i: integer value to subtract

 * @v: pointer of type atomic_t

 *

 * Atomically subtracts @i from @v.  Note that the guaranteed

 * useful range of an atomic_t is only 24 bits.

 */

static __inline__ void atomic_sub(int i, atomic_t * v)

{

        unsigned long flags;

        local_irq_save(flags);

        v->counter -= i;

        local_irq_restore(flags);

}

static __inline__ int atomic_add_return(int i, atomic_t * v)

{

        unsigned long flags;

        int temp;

        local_irq_save(flags);

        temp = v->counter;

        temp += i;

        v->counter = temp;

        local_irq_restore(flags);

        return temp;

}

static __inline__ int atomic_sub_return(int i, atomic_t * v)

{

        unsigned long flags;

        int temp;

        local_irq_save(flags);

        temp = v->counter;

        temp -= i;

        v->counter = temp;

        local_irq_restore(flags);

        return temp;

}

#else

/*

 * ... while for MIPS II and better we can use ll/sc instruction.  This

 * implementation is SMP safe ...

 */

/*

 * atomic_add - add integer to atomic variable

 * @i: integer value to add

 * @v: pointer of type atomic_t

 *

 * Atomically adds @i to @v.  Note that the guaranteed useful range

 * of an atomic_t is only 24 bits.

 */

static __inline__ void atomic_add(int i, atomic_t * v)

{

        unsigned long temp;

        __asm__ __volatile__(

                "1:   ll      %0, %1      # atomic_add\n"

                "     addu    %0, %2                  \n"

                "     sc      %0, %1                  \n"

                "     beqz    %0, 1b                  \n"

                : "=&r" (temp), "=m" (v->counter)

                : "Ir" (i), "m" (v->counter));

}

/*

 * atomic_sub - subtract the atomic variable

 * @i: integer value to subtract

 * @v: pointer of type atomic_t

 *

 * Atomically subtracts @i from @v.  Note that the guaranteed

 * useful range of an atomic_t is only 24 bits.

 */

static __inline__ void atomic_sub(int i, atomic_t * v)

{

        unsigned long temp;

        __asm__ __volatile__(

                "1:   ll      %0, %1      # atomic_sub\n"

                "     subu    %0, %2                  \n"

                "     sc      %0, %1                  \n"

                "     beqz    %0, 1b                  \n"

                : "=&r" (temp), "=m" (v->counter)

                : "Ir" (i), "m" (v->counter));

}

/*

 * Same as above, but return the result value

 */

static __inline__ int atomic_add_return(int i, atomic_t * v)

{

        unsigned long temp, result;

        __asm__ __volatile__(

                ".set push               # atomic_add_return\n"

                ".set noreorder                             \n"

                "1:   ll      %1, %2                        \n"

                "     addu    %0, %1, %3                    \n"

                "     sc      %0, %2                        \n"

                "     beqz    %0, 1b                        \n"

                "     addu    %0, %1, %3                    \n"

                "     sync                                  \n"

                ".set pop                                   \n"

                : "=&r" (result), "=&r" (temp), "=m" (v->counter)

                : "Ir" (i), "m" (v->counter)

                : "memory");

        return result;

}

static __inline__ int atomic_sub_return(int i, atomic_t * v)

{

        unsigned long temp, result;

        __asm__ __volatile__(

                ".set push                                   \n"

                ".set noreorder           # atomic_sub_return\n"

                "1:   ll    %1, %2                           \n"

                "     subu  %0, %1, %3                       \n"

                "     sc    %0, %2                           \n"

                "     beqz  %0, 1b                           \n"

                "     subu  %0, %1, %3                       \n"

                "     sync                                   \n"

                ".set pop                                    \n"

                : "=&r" (result), "=&r" (temp), "=m" (v->counter)

                : "Ir" (i), "m" (v->counter)

                : "memory");

        return result;

}

#endif

#define atomic_dec_return(v) atomic_sub_return(1,(v))

#define atomic_inc_return(v) atomic_add_return(1,(v))

/*

 * 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.  Note that the guaranteed

 * useful range of an atomic_t is only 24 bits.

 */

#define atomic_sub_and_test(i,v) (atomic_sub_return((i), (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.  Note that the guaranteed

 * useful range of an atomic_t is only 24 bits.

 */

#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)

/*

 * atomic_dec_and_test - decrement by 1 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.  Note that the guaranteed

 * useful range of an atomic_t is only 24 bits.

 */

#define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0)

/*

 * atomic_inc - increment atomic variable

 * @v: pointer of type atomic_t

 *

 * Atomically increments @v by 1.  Note that the guaranteed

 * useful range of an atomic_t is only 24 bits.

 */

#define atomic_inc(v) atomic_add(1,(v))

/*

 * atomic_dec - decrement and test

 * @v: pointer of type atomic_t

 *

 * Atomically decrements @v by 1.  Note that the guaranteed

 * useful range of an atomic_t is only 24 bits.

 */

#define atomic_dec(v) atomic_sub(1,(v))

/*

 * 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.  Note that the guaranteed

 * useful range of an atomic_t is only 24 bits.

 */

#define atomic_add_negative(i,v) (atomic_add_return(i, (v)) < 0)

/* Atomic operations are already serializing */

#define smp_mb__before_atomic_dec()     smp_mb()

#define smp_mb__after_atomic_dec()      smp_mb()

#define smp_mb__before_atomic_inc()     smp_mb()

#define smp_mb__after_atomic_inc()      smp_mb()

#endif /* defined(__KERNEL__) */

#endif /* __ASM_ATOMIC_H */