arch/x86/include/asm/io_32.h

#ifndef _ASM_X86_IO_32_H
#define _ASM_X86_IO_32_H

#include <linux/string.h>
#include <linux/compiler.h>

/*
 * This file contains the definitions for the x86 IO instructions
 * inb/inw/inl/outb/outw/outl and the "string versions" of the same
 * (insb/insw/insl/outsb/outsw/outsl). You can also use "pausing"
 * versions of the single-IO instructions (inb_p/inw_p/..).
 *
 * This file is not meant to be obfuscating: it's just complicated
 * to (a) handle it all in a way that makes gcc able to optimize it
 * as well as possible and (b) trying to avoid writing the same thing
 * over and over again with slight variations and possibly making a
 * mistake somewhere.
 */

/*
 * Thanks to James van Artsdalen for a better timing-fix than
 * the two short jumps: using outb's to a nonexistent port seems
 * to guarantee better timings even on fast machines.
 *
 * On the other hand, I'd like to be sure of a non-existent port:
 * I feel a bit unsafe about using 0x80 (should be safe, though)
 *
 *		Linus
 */

 /*
  *  Bit simplified and optimized by Jan Hubicka
  *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999.
  *
  *  isa_memset_io, isa_memcpy_fromio, isa_memcpy_toio added,
  *  isa_read[wl] and isa_write[wl] fixed
  *  - Arnaldo Carvalho de Melo <acme@conectiva.com.br>
  */

#ifdef __KERNEL__

#include <asm-generic/iomap.h>

#include <linux/vmalloc.h>

/*
 * Convert a virtual cached pointer to an uncached pointer
 */
#define xlate_dev_kmem_ptr(p)	p

static inline void
memset_io(volatile void __iomem *addr, unsigned char val, size_t count)
{
	memset((void __force *)addr, val, count);
}

static inline void
memcpy_fromio(void *dst, const volatile void __iomem *src, size_t count)
{
	memcpy(dst, (const void __force *)src, count);
}

static inline void
memcpy_toio(volatile void __iomem *dst, const void *src, size_t count)
{
	memcpy((void __force *)dst, src, count);
}

/*
 * ISA space is 'always mapped' on a typical x86 system, no need to
 * explicitly ioremap() it. The fact that the ISA IO space is mapped
 * to PAGE_OFFSET is pure coincidence - it does not mean ISA values
 * are physical addresses. The following constant pointer can be
 * used as the IO-area pointer (it can be iounmapped as well, so the
 * analogy with PCI is quite large):
 */
#define __ISA_IO_base ((char __iomem *)(PAGE_OFFSET))

/*
 *	Cache management
 *
 *	This needed for two cases
 *	1. Out of order aware processors
 *	2. Accidentally out of order processors (PPro errata #51)
 */

static inline void flush_write_buffers(void)
{
#if defined(CONFIG_X86_OOSTORE) || defined(CONFIG_X86_PPRO_FENCE)
	asm volatile("lock; addl $0,0(%%esp)": : :"memory");
#endif
}

#endif /* __KERNEL__ */

extern void native_io_delay(void);

extern int io_delay_type;
extern void io_delay_init(void);

#if defined(CONFIG_PARAVIRT)
#include <asm/paravirt.h>
#else

static inline void slow_down_io(void)
{
	native_io_delay();
#ifdef REALLY_SLOW_IO
	native_io_delay();
	native_io_delay();
	native_io_delay();
#endif
}

#endif

#define BUILDIO(bwl, bw, type)						\
static inline void out##bwl(unsigned type value, int port)		\
{									\
	asm volatile("out" #bwl " %" #bw "0, %w1"			\
		     : : "a"(value), "Nd"(port));			\
}									\
									\
static inline unsigned type in##bwl(int port)				\
{									\
	unsigned type value;						\
	asm volatile("in" #bwl " %w1, %" #bw "0"			\
		     : "=a"(value) : "Nd"(port));			\
	return value;							\
}									\
									\
static inline void out##bwl##_p(unsigned type value, int port)		\
{									\
	out##bwl(value, port);						\
	slow_down_io();							\
}									\
									\
static inline unsigned type in##bwl##_p(int port)			\
{									\
	unsigned type value = in##bwl(port);				\
	slow_down_io();							\
	return value;							\
}									\
									\
static inline void outs##bwl(int port, const void *addr, unsigned long count) \
{									\
	asm volatile("rep; outs" #bwl					\
		     : "+S"(addr), "+c"(count) : "d"(port));		\
}									\
									\
static inline void ins##bwl(int port, void *addr, unsigned long count)	\
{									\
	asm volatile("rep; ins" #bwl					\
		     : "+D"(addr), "+c"(count) : "d"(port));		\
}

BUILDIO(b, b, char)
BUILDIO(w, w, short)
BUILDIO(l, , int)

#endif /* _ASM_X86_IO_32_H */