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/cmpxchg-local.h>
 23#include <asm/cmpxchg.h>
 24
 25struct task_struct;
 26
 27/* context switching is now performed out-of-line in switch_to.S */
 28extern 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#define nop() asm volatile ("nop")
 38
 39#endif /* !__ASSEMBLY__ */
 40
 41/*
 42 * Force strict CPU ordering.
 43 * And yes, this is required on UP too when we're talking
 44 * to devices.
 45 *
 46 * This implementation only contains a compiler barrier.
 47 */
 48
 49#define mb()	asm volatile ("": : :"memory")
 50#define rmb()	mb()
 51#define wmb()	asm volatile ("": : :"memory")
 52
 53#ifdef CONFIG_SMP
 54#define smp_mb()	mb()
 55#define smp_rmb()	rmb()
 56#define smp_wmb()	wmb()
 57#else
 58#define smp_mb()	barrier()
 59#define smp_rmb()	barrier()
 60#define smp_wmb()	barrier()
 61#endif
 62
 63#define set_mb(var, value)  do { var = value;  mb(); } while (0)
 64#define set_wmb(var, value) do { var = value; wmb(); } while (0)
 65
 66#define read_barrier_depends()		do {} while (0)
 67#define smp_read_barrier_depends()	do {} while (0)
 68
 69/*
 70 * we make sure local_irq_enable() doesn't cause priority inversion
 71 */
 72#ifndef __ASSEMBLY__
 73
 74/* This function doesn't exist, so you'll get a linker error
 75 *    if something tries to do an invalid xchg().  */
 76extern void __xchg_called_with_bad_pointer(void);
 77
 78static inline
 79unsigned long __xchg(unsigned long x, volatile void *ptr, int size)
 80{
 81	unsigned long ret, flags;
 82
 83	switch (size) {
 84	case 1:
 85#ifdef __xchg_u8
 86		return __xchg_u8(x, ptr);
 87#else
 88		local_irq_save(flags);
 89		ret = *(volatile u8 *)ptr;
 90		*(volatile u8 *)ptr = x;
 91		local_irq_restore(flags);
 92		return ret;
 93#endif /* __xchg_u8 */
 94
 95	case 2:
 96#ifdef __xchg_u16
 97		return __xchg_u16(x, ptr);
 98#else
 99		local_irq_save(flags);
100		ret = *(volatile u16 *)ptr;
101		*(volatile u16 *)ptr = x;
102		local_irq_restore(flags);
103		return ret;
104#endif /* __xchg_u16 */
105
106	case 4:
107#ifdef __xchg_u32
108		return __xchg_u32(x, ptr);
109#else
110		local_irq_save(flags);
111		ret = *(volatile u32 *)ptr;
112		*(volatile u32 *)ptr = x;
113		local_irq_restore(flags);
114		return ret;
115#endif /* __xchg_u32 */
116
117#ifdef CONFIG_64BIT
118	case 8:
119#ifdef __xchg_u64
120		return __xchg_u64(x, ptr);
121#else
122		local_irq_save(flags);
123		ret = *(volatile u64 *)ptr;
124		*(volatile u64 *)ptr = x;
125		local_irq_restore(flags);
126		return ret;
127#endif /* __xchg_u64 */
128#endif /* CONFIG_64BIT */
129
130	default:
131		__xchg_called_with_bad_pointer();
132		return x;
133	}
134}
135
136#define xchg(ptr, x) \
137	((__typeof__(*(ptr))) __xchg((unsigned long)(x), (ptr), sizeof(*(ptr))))
138
139#endif /* !__ASSEMBLY__ */
140
141#endif /* __ASM_GENERIC_SYSTEM_H */