arch/x86/include/asm/io.h

#ifndef _ASM_IO_H
#define _ASM_IO_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>
  */

#define IO_SPACE_LIMIT 0xffff

#include <asm/types.h>


#ifdef __KERNEL__


/*
 * readX/writeX() are used to access memory mapped devices. On some
 * architectures the memory mapped IO stuff needs to be accessed
 * differently. On the x86 architecture, we just read/write the
 * memory location directly.
 */

#define readb(addr) (*(volatile unsigned char *) (addr))
#define readw(addr) (*(volatile unsigned short *) (addr))
#define readl(addr) (*(volatile unsigned int *) (addr))
#define __raw_readb readb
#define __raw_readw readw
#define __raw_readl readl

#define writeb(b,addr) (*(volatile unsigned char *) (addr) = (b))
#define writew(b,addr) (*(volatile unsigned short *) (addr) = (b))
#define writel(b,addr) (*(volatile unsigned int *) (addr) = (b))
#define __raw_writeb writeb
#define __raw_writew writew
#define __raw_writel writel

#define memset_io(a,b,c)	memset((a),(b),(c))
#define memcpy_fromio(a,b,c)	memcpy((a),(b),(c))
#define memcpy_toio(a,b,c)	memcpy((a),(b),(c))

/*
 * 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_readb(a) readb((a))
#define isa_readw(a) readw((a))
#define isa_readl(a) readl((a))
#define isa_writeb(b,a) writeb(b,(a))
#define isa_writew(w,a) writew(w,(a))
#define isa_writel(l,a) writel(l,(a))
#define isa_memset_io(a,b,c)		memset_io((a),(b),(c))
#define isa_memcpy_fromio(a,b,c)	memcpy_fromio((a),(b),(c))
#define isa_memcpy_toio(a,b,c)		memcpy_toio((a),(b),(c))


static inline int check_signature(unsigned long io_addr,
	const unsigned char *signature, int length)
{
	int retval = 0;
	do {
		if (readb(io_addr) != *signature)
			goto out;
		io_addr++;
		signature++;
		length--;
	} while (length);
	retval = 1;
out:
	return retval;
}

/**
 *	isa_check_signature		-	find BIOS signatures
 *	@io_addr: mmio address to check
 *	@signature:  signature block
 *	@length: length of signature
 *
 *	Perform a signature comparison with the ISA mmio address io_addr.
 *	Returns 1 on a match.
 *
 *	This function is deprecated. New drivers should use ioremap and
 *	check_signature.
 */


static inline int isa_check_signature(unsigned long io_addr,
	const unsigned char *signature, int length)
{
	int retval = 0;
	do {
		if (isa_readb(io_addr) != *signature)
			goto out;
		io_addr++;
		signature++;
		length--;
	} while (length);
	retval = 1;
out:
	return retval;
}

#endif /* __KERNEL__ */

#ifdef SLOW_IO_BY_JUMPING
#define __SLOW_DOWN_IO "\njmp 1f\n1:\tjmp 1f\n1:"
#else
#define __SLOW_DOWN_IO "\noutb %%al,$0xed"
#endif

#ifdef REALLY_SLOW_IO
#define __FULL_SLOW_DOWN_IO __SLOW_DOWN_IO __SLOW_DOWN_IO __SLOW_DOWN_IO __SLOW_DOWN_IO
#else
#define __FULL_SLOW_DOWN_IO __SLOW_DOWN_IO
#endif


/*
 * Talk about misusing macros..
 */
#define __OUT1(s,x) \
static inline void out##s(unsigned x value, unsigned short port) {

#define __OUT2(s,s1,s2) \
__asm__ __volatile__ ("out" #s " %" s1 "0,%" s2 "1"


#define __OUT(s,s1,x) \
__OUT1(s,x) __OUT2(s,s1,"w") : : "a" (value), "Nd" (port)); } \
__OUT1(s##_p,x) __OUT2(s,s1,"w") __FULL_SLOW_DOWN_IO : : "a" (value), "Nd" (port));}

#define __IN1(s) \
static inline RETURN_TYPE in##s(unsigned short port) { RETURN_TYPE _v;

#define __IN2(s,s1,s2) \
__asm__ __volatile__ ("in" #s " %" s2 "1,%" s1 "0"

#define __IN(s,s1,i...) \
__IN1(s) __IN2(s,s1,"w") : "=a" (_v) : "Nd" (port) ,##i ); return _v; } \
__IN1(s##_p) __IN2(s,s1,"w") __FULL_SLOW_DOWN_IO : "=a" (_v) : "Nd" (port) ,##i ); return _v; }

#define __INS(s) \
static inline void ins##s(unsigned short port, void * addr, unsigned long count) \
{ __asm__ __volatile__ ("rep ; ins" #s \
: "=D" (addr), "=c" (count) : "d" (port),"0" (addr),"1" (count)); }

#define __OUTS(s) \
static inline void outs##s(unsigned short port, const void * addr, unsigned long count) \
{ __asm__ __volatile__ ("rep ; outs" #s \
: "=S" (addr), "=c" (count) : "d" (port),"0" (addr),"1" (count)); }

#define RETURN_TYPE unsigned char
__IN(b,"")
#undef RETURN_TYPE
#define RETURN_TYPE unsigned short
__IN(w,"")
#undef RETURN_TYPE
#define RETURN_TYPE unsigned int
__IN(l,"")
#undef RETURN_TYPE

__OUT(b,"b",char)
__OUT(w,"w",short)
__OUT(l,,int)

__INS(b)
__INS(w)
__INS(l)

__OUTS(b)
__OUTS(w)
__OUTS(l)

static inline void sync(void)
{
}

/*
 * Given a physical address and a length, return a virtual address
 * that can be used to access the memory range with the caching
 * properties specified by "flags".
 */
#define MAP_NOCACHE	(0)
#define MAP_WRCOMBINE	(0)
#define MAP_WRBACK	(0)
#define MAP_WRTHROUGH	(0)

static inline void *
map_physmem(phys_addr_t paddr, unsigned long len, unsigned long flags)
{
	return (void *)paddr;
}

/*
 * Take down a mapping set up by map_physmem().
 */
static inline void unmap_physmem(void *vaddr, unsigned long flags)
{

}

static inline phys_addr_t virt_to_phys(void * vaddr)
{
	return (phys_addr_t)(vaddr);
}

/*
 * TODO: The kernel offers some more advanced versions of barriers, it might
 * have some advantages to use them instead of the simple one here.
 */
#define dmb()		__asm__ __volatile__ ("" : : : "memory")
#define __iormb()	dmb()
#define __iowmb()	dmb()

#endif