/*
   * Generic C implementation of atomic counter operations. Usable on
   * UP systems only. Do not include in machine independent code.
   *
   * Originally implemented for MN10300.
   *
   * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public Licence
   * as published by the Free Software Foundation; either version
   * 2 of the Licence, or (at your option) any later version.
   */
  #ifndef __ASM_GENERIC_ATOMIC_H
  #define __ASM_GENERIC_ATOMIC_H
  
  #include <asm/cmpxchg.h>
  
  #ifdef CONFIG_SMP
  /* Force people to define core atomics */
  # if !defined(atomic_add_return) || !defined(atomic_sub_return) || \
       !defined(atomic_clear_mask) || !defined(atomic_set_mask)
  #  error "SMP requires a little arch-specific magic"
  # endif
  #endif
  
  /*
   * Atomic operations that C can't guarantee us.  Useful for
   * resource counting etc..
   */
  
  #define ATOMIC_INIT(i)	{ (i) }
  
  #ifdef __KERNEL__
  
  /**
   * atomic_read - read atomic variable
   * @v: pointer of type atomic_t
   *
   * Atomically reads the value of @v.
   */
  #ifndef atomic_read
  #define atomic_read(v)	(*(volatile int *)&(v)->counter)
  #endif
  
  /**
   * 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))
  
  #include <linux/irqflags.h>
  
  /**
   * atomic_add_return - add integer to atomic variable
   * @i: integer value to add
   * @v: pointer of type atomic_t
   *
   * Atomically adds @i to @v and returns the result
   */
  #ifndef atomic_add_return
  static inline int atomic_add_return(int i, atomic_t *v)
  {
  	unsigned long flags;
  	int temp;
  
  	raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */
  	temp = v->counter;
  	temp += i;
  	v->counter = temp;
  	raw_local_irq_restore(flags);
  
  	return temp;
  }
  #endif
  
  /**
   * atomic_sub_return - subtract integer from atomic variable
   * @i: integer value to subtract
   * @v: pointer of type atomic_t
   *
   * Atomically subtracts @i from @v and returns the result
   */
  #ifndef atomic_sub_return
  static inline int atomic_sub_return(int i, atomic_t *v)
  {
  	unsigned long flags;
  	int temp;
  
  	raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */
  	temp = v->counter;
  	temp -= i;
  	v->counter = temp;
  	raw_local_irq_restore(flags);
  
  	return temp;
  }
  #endif
  
  static inline int atomic_add_negative(int i, atomic_t *v)
  {
  	return atomic_add_return(i, v) < 0;
  }
  
  static inline void atomic_add(int i, atomic_t *v)
  {
  	atomic_add_return(i, v);
  }
  
  static inline void atomic_sub(int i, atomic_t *v)
  {
  	atomic_sub_return(i, v);
  }
  
  static inline void atomic_inc(atomic_t *v)
  {
  	atomic_add_return(1, v);
  }
  
  static inline void atomic_dec(atomic_t *v)
  {
  	atomic_sub_return(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_dec_and_test(v)		(atomic_dec_return(v) == 0)
  #define atomic_inc_and_test(v)		(atomic_inc_return(v) == 0)
  
  #define atomic_xchg(ptr, v)		(xchg(&(ptr)->counter, (v)))
  #define atomic_cmpxchg(v, old, new)	(cmpxchg(&((v)->counter), (old), (new)))
  
  static inline int __atomic_add_unless(atomic_t *v, int a, int u)
  {
    int c, old;
    c = atomic_read(v);
    while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
      c = old;
    return c;
  }
  
  /**
   * atomic_clear_mask - Atomically clear bits in atomic variable
   * @mask: Mask of the bits to be cleared
   * @v: pointer of type atomic_t
   *
   * Atomically clears the bits set in @mask from @v
   */
  #ifndef atomic_clear_mask
  static inline void atomic_clear_mask(unsigned long mask, atomic_t *v)
  {
  	unsigned long flags;
  
  	mask = ~mask;
  	raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
  	v->counter &= mask;
  	raw_local_irq_restore(flags);
  }
  #endif
  
  /**
   * atomic_set_mask - Atomically set bits in atomic variable
   * @mask: Mask of the bits to be set
   * @v: pointer of type atomic_t
   *
   * Atomically sets the bits set in @mask in @v
   */
  #ifndef atomic_set_mask
  static inline void atomic_set_mask(unsigned int mask, atomic_t *v)
  {
  	unsigned long flags;
  
  	raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
  	v->counter |= mask;
  	raw_local_irq_restore(flags);
  }
  #endif
  
  /* Assume that 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()
  
  #endif /* __KERNEL__ */
  #endif /* __ASM_GENERIC_ATOMIC_H */