arch/arm/include/asm/proc-armv/system.h

/*
 *  linux/include/asm-arm/proc-armv/system.h
 *
 *  Copyright (C) 1996 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#ifndef __ASM_PROC_SYSTEM_H
#define __ASM_PROC_SYSTEM_H

#include <linux/config.h>

/*
 * Save the current interrupt enable state & disable IRQs
 */
#define local_irq_save(x)					\
	({							\
		unsigned long temp;				\
	__asm__ __volatile__(					\
	"mrs	%0, cpsr		@ local_irq_save\n"	\
"	orr	%1, %0, #128\n"					\
"	msr	cpsr_c, %1"					\
	: "=r" (x), "=r" (temp)					\
	:							\
	: "memory");						\
	})

/*
 * Enable IRQs
 */
#define local_irq_enable()					\
	({							\
		unsigned long temp;				\
	__asm__ __volatile__(					\
	"mrs	%0, cpsr		@ local_irq_enable\n"	\
"	bic	%0, %0, #128\n"					\
"	msr	cpsr_c, %0"					\
	: "=r" (temp)						\
	:							\
	: "memory");						\
	})

/*
 * Disable IRQs
 */
#define local_irq_disable()					\
	({							\
		unsigned long temp;				\
	__asm__ __volatile__(					\
	"mrs	%0, cpsr		@ local_irq_disable\n"	\
"	orr	%0, %0, #128\n"					\
"	msr	cpsr_c, %0"					\
	: "=r" (temp)						\
	:							\
	: "memory");						\
	})

/*
 * Enable FIQs
 */
#define __stf()							\
	({							\
		unsigned long temp;				\
	__asm__ __volatile__(					\
	"mrs	%0, cpsr		@ stf\n"		\
"	bic	%0, %0, #64\n"					\
"	msr	cpsr_c, %0"					\
	: "=r" (temp)						\
	:							\
	: "memory");						\
	})

/*
 * Disable FIQs
 */
#define __clf()							\
	({							\
		unsigned long temp;				\
	__asm__ __volatile__(					\
	"mrs	%0, cpsr		@ clf\n"		\
"	orr	%0, %0, #64\n"					\
"	msr	cpsr_c, %0"					\
	: "=r" (temp)						\
	:							\
	: "memory");						\
	})

/*
 * Save the current interrupt enable state.
 */
#define local_save_flags(x)					\
	({							\
	__asm__ __volatile__(					\
	"mrs	%0, cpsr		@ local_save_flags\n"	\
	  : "=r" (x)						\
	  :							\
	  : "memory");						\
	})

/*
 * restore saved IRQ & FIQ state
 */
#define local_irq_restore(x)					\
	__asm__ __volatile__(					\
	"msr	cpsr_c, %0		@ local_irq_restore\n"	\
	:							\
	: "r" (x)						\
	: "memory")

#if defined(CONFIG_CPU_SA1100) || defined(CONFIG_CPU_SA110)
/*
 * On the StrongARM, "swp" is terminally broken since it bypasses the
 * cache totally.  This means that the cache becomes inconsistent, and,
 * since we use normal loads/stores as well, this is really bad.
 * Typically, this causes oopsen in filp_close, but could have other,
 * more disasterous effects.  There are two work-arounds:
 *  1. Disable interrupts and emulate the atomic swap
 *  2. Clean the cache, perform atomic swap, flush the cache
 *
 * We choose (1) since its the "easiest" to achieve here and is not
 * dependent on the processor type.
 */
#define swp_is_buggy
#endif

static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size)
{
	extern void __bad_xchg(volatile void *, int);
	unsigned long ret;
#ifdef swp_is_buggy
	unsigned long flags;
#endif

	switch (size) {
#ifdef swp_is_buggy
		case 1:
			local_irq_save(flags);
			ret = *(volatile unsigned char *)ptr;
			*(volatile unsigned char *)ptr = x;
			local_irq_restore(flags);
			break;

		case 4:
			local_irq_save(flags);
			ret = *(volatile unsigned long *)ptr;
			*(volatile unsigned long *)ptr = x;
			local_irq_restore(flags);
			break;
#else
		case 1:	__asm__ __volatile__ ("swpb %0, %1, [%2]"
					: "=&r" (ret)
					: "r" (x), "r" (ptr)
					: "memory");
			break;
		case 4:	__asm__ __volatile__ ("swp %0, %1, [%2]"
					: "=&r" (ret)
					: "r" (x), "r" (ptr)
					: "memory");
			break;
#endif
		default: __bad_xchg(ptr, size), ret = 0;
	}

	return ret;
}

#endif