include/asm-generic/system.h

   1 /* Generic system definitions, based on MN10300 definitions.
   2  *
   3  * It should be possible to use these on really simple architectures,
   4  * but it serves more as a starting point for new ports.
   5  *
   6  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   7  * Written by David Howells (dhowells@redhat.com)
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public Licence
  11  * as published by the Free Software Foundation; either version
  12  * 2 of the Licence, or (at your option) any later version.
  13  */
  14 #ifndef __ASM_GENERIC_SYSTEM_H
  15 #define __ASM_GENERIC_SYSTEM_H
  16
  17 #ifndef __ASSEMBLY__
  18
  19 #include <linux/types.h>
  20 #include <linux/irqflags.h>
  21
  22 #include <asm/barrier.h>
  23 #include <asm/cmpxchg.h>
  24
  25 struct task_struct;
  26
  27 /* context switching is now performed out-of-line in switch_to.S */
  28 extern struct task_struct *__switch_to(struct task_struct *,
  29                 struct task_struct *);
  30 #define switch_to(prev, next, last)                                     \
  31         do {                                                            \
  32                 ((last) = __switch_to((prev), (next)));                 \
  33         } while (0)
  34
  35 #define arch_align_stack(x) (x)
  36
  37 /*
  38  * we make sure local_irq_enable() doesn't cause priority inversion
  39  */
  40
  41 /* This function doesn't exist, so you'll get a linker error
  42  *    if something tries to do an invalid xchg().  */
  43 extern void __xchg_called_with_bad_pointer(void);
  44
  45 static inline
  46 unsigned long __xchg(unsigned long x, volatile void *ptr, int size)
  47 {
  48         unsigned long ret, flags;
  49
  50         switch (size) {
  51         case 1:
  52 #ifdef __xchg_u8
  53                 return __xchg_u8(x, ptr);
  54 #else
  55                 local_irq_save(flags);
  56                 ret = *(volatile u8 *)ptr;
  57                 *(volatile u8 *)ptr = x;
  58                 local_irq_restore(flags);
  59                 return ret;
  60 #endif /* __xchg_u8 */
  61
  62         case 2:
  63 #ifdef __xchg_u16
  64                 return __xchg_u16(x, ptr);
  65 #else
  66                 local_irq_save(flags);
  67                 ret = *(volatile u16 *)ptr;
  68                 *(volatile u16 *)ptr = x;
  69                 local_irq_restore(flags);
  70                 return ret;
  71 #endif /* __xchg_u16 */
  72
  73         case 4:
  74 #ifdef __xchg_u32
  75                 return __xchg_u32(x, ptr);
  76 #else
  77                 local_irq_save(flags);
  78                 ret = *(volatile u32 *)ptr;
  79                 *(volatile u32 *)ptr = x;
  80                 local_irq_restore(flags);
  81                 return ret;
  82 #endif /* __xchg_u32 */
  83
  84 #ifdef CONFIG_64BIT
  85         case 8:
  86 #ifdef __xchg_u64
  87                 return __xchg_u64(x, ptr);
  88 #else
  89                 local_irq_save(flags);
  90                 ret = *(volatile u64 *)ptr;
  91                 *(volatile u64 *)ptr = x;
  92                 local_irq_restore(flags);
  93                 return ret;
  94 #endif /* __xchg_u64 */
  95 #endif /* CONFIG_64BIT */
  96
  97         default:
  98                 __xchg_called_with_bad_pointer();
  99                 return x;
 100         }
 101 }
 102
 103 #define xchg(ptr, x) \
 104         ((__typeof__(*(ptr))) __xchg((unsigned long)(x), (ptr), sizeof(*(ptr))))
 105
 106 #endif /* !__ASSEMBLY__ */
 107
 108 #endif /* __ASM_GENERIC_SYSTEM_H */