/* MN10300 System definitions
*
* 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_SYSTEM_H
#define _ASM_SYSTEM_H
#include <asm/cpu-regs.h>
#ifdef __KERNEL__
#ifndef __ASSEMBLY__
#include <linux/kernel.h>
#include <linux/irqflags.h>
struct task_struct;
struct thread_struct;
extern asmlinkage
struct task_struct *__switch_to(struct thread_struct *prev,
struct thread_struct *next,
struct task_struct *prev_task);
/* context switching is now performed out-of-line in switch_to.S */
#define switch_to(prev, next, last) \
do { \
current->thread.wchan = (u_long) __builtin_return_address(0); \
(last) = __switch_to(&(prev)->thread, &(next)->thread, (prev)); \
mb(); \
current->thread.wchan = 0; \
} 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.
*
* For now, "wmb()" doesn't actually do anything, as all
* Intel CPU's follow what Intel calls a *Processor Order*,
* in which all writes are seen in the program order even
* outside the CPU.
*
* I expect future Intel CPU's to have a weaker ordering,
* but I'd also expect them to finally get their act together
* and add some real memory barriers if so.
*
* Some non intel clones support out of order store. wmb() ceases to be a
* nop for these.
*/
#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)
/*****************************************************************************/
/*
* MN10300 doesn't actually have an exchange instruction
*/
#ifndef __ASSEMBLY__
struct __xchg_dummy { unsigned long a[100]; };
#define __xg(x) ((struct __xchg_dummy *)(x))
static inline
unsigned long __xchg(volatile unsigned long *m, unsigned long val)
{
unsigned long retval;
unsigned long flags;
local_irq_save(flags);
retval = *m;
*m = val;
local_irq_restore(flags);
return retval;
}
#define xchg(ptr, v) \
((__typeof__(*(ptr))) __xchg((unsigned long *)(ptr), \
(unsigned long)(v)))
static inline unsigned long __cmpxchg(volatile unsigned long *m,
unsigned long old, unsigned long new)
{
unsigned long retval;
unsigned long flags;
local_irq_save(flags);
retval = *m;
if (retval == old)
*m = new;
local_irq_restore(flags);
return retval;
}
#define cmpxchg(ptr, o, n) \
((__typeof__(*(ptr))) __cmpxchg((unsigned long *)(ptr), \
(unsigned long)(o), \
(unsigned long)(n)))
#endif /* !__ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _ASM_SYSTEM_H */
