/* Generic system definitions, based on MN10300 definitions. * * It should be possible to use these on really simple architectures, * but it serves more as a starting point for new ports. * * 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_SYSTEM_H#define __ASM_GENERIC_SYSTEM_H #ifdef __KERNEL__#ifndef __ASSEMBLY__ #include <linux/types.h>#include <linux/irqflags.h> #include <asm/cmpxchg-local.h>#include <asm/cmpxchg.h> struct task_struct; /* context switching is now performed out-of-line in switch_to.S */extern struct task_struct *__switch_to(struct task_struct *,		struct task_struct *);#define switch_to(prev, next, last)					\	do {								\		((last) = __switch_to((prev), (next)));			\	} while (0) #define arch_align_stack(x) (x) #define nop() asm volatile ("nop") #endif /* !__ASSEMBLY__ */ /* * Force strict CPU ordering. * And yes, this is required on UP too when we're talking * to devices. * * This implementation only contains a compiler barrier. */ #define mb()	asm volatile ("": : :"memory")#define rmb()	mb()#define wmb()	asm volatile ("": : :"memory") #ifdef CONFIG_SMP#define smp_mb()	mb()#define smp_rmb()	rmb()#define smp_wmb()	wmb()#else#define smp_mb()	barrier()#define smp_rmb()	barrier()#define smp_wmb()	barrier()#endif #define set_mb(var, value)  do { var = value;  mb(); } while (0)#define set_wmb(var, value) do { var = value; wmb(); } while (0) #define read_barrier_depends()		do {} while (0)#define smp_read_barrier_depends()	do {} while (0) /* * we make sure local_irq_enable() doesn't cause priority inversion */#ifndef __ASSEMBLY__ /* This function doesn't exist, so you'll get a linker error *    if something tries to do an invalid xchg().  */extern void __xchg_called_with_bad_pointer(void); static inlineunsigned long __xchg(unsigned long x, volatile void *ptr, int size){	unsigned long ret, flags; 	switch (size) {	case 1:#ifdef __xchg_u8		return __xchg_u8(x, ptr);#else		local_irq_save(flags);		ret = *(volatile u8 *)ptr;		*(volatile u8 *)ptr = x;		local_irq_restore(flags);		return ret;#endif /* __xchg_u8 */ 	case 2:#ifdef __xchg_u16		return __xchg_u16(x, ptr);#else		local_irq_save(flags);		ret = *(volatile u16 *)ptr;		*(volatile u16 *)ptr = x;		local_irq_restore(flags);		return ret;#endif /* __xchg_u16 */ 	case 4:#ifdef __xchg_u32		return __xchg_u32(x, ptr);#else		local_irq_save(flags);		ret = *(volatile u32 *)ptr;		*(volatile u32 *)ptr = x;		local_irq_restore(flags);		return ret;#endif /* __xchg_u32 */ #ifdef CONFIG_64BIT	case 8:#ifdef __xchg_u64		return __xchg_u64(x, ptr);#else		local_irq_save(flags);		ret = *(volatile u64 *)ptr;		*(volatile u64 *)ptr = x;		local_irq_restore(flags);		return ret;#endif /* __xchg_u64 */#endif /* CONFIG_64BIT */ 	default:		__xchg_called_with_bad_pointer();		return x;	}} #define xchg(ptr, x) \	((__typeof__(*(ptr))) __xchg((unsigned long)(x), (ptr), sizeof(*(ptr)))) #endif /* !__ASSEMBLY__ */ #endif /* __KERNEL__ */#endif /* __ASM_GENERIC_SYSTEM_H */