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[ioapi] Formalise the I/O API as used in i386-pcbios
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Michael Brown committed Oct 12, 2008
1 parent b40b4f2 commit 8956a36
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93 changes: 93 additions & 0 deletions src/arch/i386/core/x86_io.c
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/*
* Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <gpxe/io.h>
#include <gpxe/x86_io.h>

/** @file
*
* gPXE I/O API for x86
*
*/

/**
* Read 64-bit qword from memory-mapped device
*
* @v io_addr I/O address
* @ret data Value read
*
* This routine uses MMX instructions.
*/
static uint64_t x86_readq ( volatile uint64_t *io_addr ) {
uint64_t data;
__asm__ __volatile__ ( "pushl %%edx\n\t"
"pushl %%eax\n\t"
"movq (%1), %%mm0\n\t"
"movq %%mm0, (%%esp)\n\t"
"popl %%eax\n\t"
"popl %%edx\n\t"
"emms\n\t"
: "=A" ( data ) : "r" ( io_addr ) );
return data;
}

/**
* Write 64-bit qword to memory-mapped device
*
* @v data Value to write
* @v io_addr I/O address
*
* This routine uses MMX instructions.
*/
static void x86_writeq ( uint64_t data, volatile uint64_t *io_addr ) {
__asm__ __volatile__ ( "pushl %%edx\n\t"
"pushl %%eax\n\t"
"movq (%%esp), %%mm0\n\t"
"movq %%mm0, (%1)\n\t"
"popl %%eax\n\t"
"popl %%edx\n\t"
"emms\n\t"
: : "A" ( data ), "r" ( io_addr ) );
}

PROVIDE_IOAPI_INLINE ( x86, iounmap );
PROVIDE_IOAPI_INLINE ( x86, io_to_bus );
PROVIDE_IOAPI_INLINE ( x86, virt_to_bus );
PROVIDE_IOAPI_INLINE ( x86, bus_to_virt );
PROVIDE_IOAPI_INLINE ( x86, readb );
PROVIDE_IOAPI_INLINE ( x86, readw );
PROVIDE_IOAPI_INLINE ( x86, readl );
PROVIDE_IOAPI ( x86, readq, x86_readq );
PROVIDE_IOAPI_INLINE ( x86, writeb );
PROVIDE_IOAPI_INLINE ( x86, writew );
PROVIDE_IOAPI_INLINE ( x86, writel );
PROVIDE_IOAPI ( x86, writeq, x86_writeq );
PROVIDE_IOAPI_INLINE ( x86, inb );
PROVIDE_IOAPI_INLINE ( x86, inw );
PROVIDE_IOAPI_INLINE ( x86, inl );
PROVIDE_IOAPI_INLINE ( x86, outb );
PROVIDE_IOAPI_INLINE ( x86, outw );
PROVIDE_IOAPI_INLINE ( x86, outl );
PROVIDE_IOAPI_INLINE ( x86, insb );
PROVIDE_IOAPI_INLINE ( x86, insw );
PROVIDE_IOAPI_INLINE ( x86, insl );
PROVIDE_IOAPI_INLINE ( x86, outsb );
PROVIDE_IOAPI_INLINE ( x86, outsw );
PROVIDE_IOAPI_INLINE ( x86, outsl );
PROVIDE_IOAPI_INLINE ( x86, iodelay );
PROVIDE_IOAPI_INLINE ( x86, mb );
12 changes: 12 additions & 0 deletions src/arch/i386/include/bits/io.h
@@ -0,0 +1,12 @@
#ifndef _BITS_IO_H
#define _BITS_IO_H

/** @file
*
* i386-specific I/O API implementations
*
*/

#include <gpxe/x86_io.h>

#endif /* _BITS_IO_H */
148 changes: 148 additions & 0 deletions src/arch/i386/include/gpxe/x86_io.h
@@ -0,0 +1,148 @@
#ifndef _GPXE_X86_IO_H
#define _GPXE_X86_IO_H

/** @file
*
* gPXE I/O API for x86
*
* i386 uses direct pointer dereferences for accesses to memory-mapped
* I/O space, and the inX/outX instructions for accesses to
* port-mapped I/O space.
*
* 64-bit atomic accesses (readq() and writeq()) use MMX instructions,
* and will crash original Pentium and earlier CPUs. Fortunately, no
* hardware that requires atomic 64-bit accesses will physically fit
* into a machine with such an old CPU anyway.
*/

#include <virtaddr.h>

#ifdef IOAPI_X86
#define IOAPI_PREFIX_x86
#else
#define IOAPI_PREFIX_x86 __x86_
#endif

/*
* Memory space mappings
*
*/

static inline __always_inline void *
IOAPI_INLINE ( x86, ioremap ) ( unsigned long bus_addr, size_t len __unused ) {
return phys_to_virt ( bus_addr );
}

static inline __always_inline void
IOAPI_INLINE ( x86, iounmap ) ( volatile const void *io_addr __unused ) {
/* Nothing to do */
}

static inline __always_inline unsigned long
IOAPI_INLINE ( x86, io_to_bus ) ( volatile const void *io_addr ) {
return virt_to_phys ( io_addr );
}

static inline __always_inline unsigned long
IOAPI_INLINE ( x86, virt_to_bus ) ( volatile const void *addr ) {
return virt_to_phys ( addr );
}

static inline __always_inline void *
IOAPI_INLINE ( x86, bus_to_virt ) ( unsigned long bus_addr ) {
return phys_to_virt ( bus_addr );
}

/*
* MMIO reads and writes up to 32 bits
*
*/

#define X86_READX( _api_func, _type ) \
static inline __always_inline _type \
IOAPI_INLINE ( x86, _api_func ) ( volatile _type *io_addr ) { \
return *io_addr; \
}
X86_READX ( readb, uint8_t );
X86_READX ( readw, uint16_t );
X86_READX ( readl, uint32_t );

#define X86_WRITEX( _api_func, _type ) \
static inline __always_inline void \
IOAPI_INLINE ( x86, _api_func ) ( _type data, \
volatile _type *io_addr ) { \
*io_addr = data; \
}
X86_WRITEX ( writeb, uint8_t );
X86_WRITEX ( writew, uint16_t );
X86_WRITEX ( writel, uint32_t );

/*
* PIO reads and writes up to 32 bits
*
*/

#define X86_INX( _insn_suffix, _type, _reg_prefix ) \
static inline __always_inline _type \
IOAPI_INLINE ( x86, in ## _insn_suffix ) ( volatile _type *io_addr ) { \
_type data; \
__asm__ __volatile__ ( "in" #_insn_suffix " %w1, %" _reg_prefix "0" \
: "=a" ( data ) : "Nd" ( io_addr ) ); \
return data; \
} \
static inline __always_inline void \
IOAPI_INLINE ( x86, ins ## _insn_suffix ) ( volatile _type *io_addr, \
_type *data, \
unsigned int count ) { \
unsigned int discard_D; \
__asm__ __volatile__ ( "rep ins" #_insn_suffix \
: "=D" ( discard_D ) \
: "d" ( io_addr ), "c" ( count ), \
"0" ( data ) ); \
}
X86_INX ( b, uint8_t, "b" );
X86_INX ( w, uint16_t, "w" );
X86_INX ( l, uint32_t, "k" );

#define X86_OUTX( _insn_suffix, _type, _reg_prefix ) \
static inline __always_inline void \
IOAPI_INLINE ( x86, out ## _insn_suffix ) ( _type data, \
volatile _type *io_addr ) { \
__asm__ __volatile__ ( "out" #_insn_suffix " %" _reg_prefix "0, %w1" \
: : "a" ( data ), "Nd" ( io_addr ) ); \
} \
static inline __always_inline void \
IOAPI_INLINE ( x86, outs ## _insn_suffix ) ( volatile _type *io_addr, \
const _type *data, \
unsigned int count ) { \
unsigned int discard_D; \
__asm__ __volatile__ ( "rep outs" #_insn_suffix \
: "=D" ( discard_D ) \
: "d" ( io_addr ), "c" ( count ), \
"0" ( data ) ); \
}
X86_OUTX ( b, uint8_t, "b" );
X86_OUTX ( w, uint16_t, "w" );
X86_OUTX ( l, uint32_t, "k" );

/*
* Slow down I/O
*
*/

static inline __always_inline void
IOAPI_INLINE ( x86, iodelay ) ( void ) {
__asm__ __volatile__ ( "outb %al, $0x80" );
}

/*
* Memory barrier
*
*/

static inline __always_inline void
IOAPI_INLINE ( x86, mb ) ( void ) {
__asm__ __volatile__ ( "lock; addl $0, 0(%%esp)" : : : "memory" );
}

#endif /* _GPXE_X86_IO_H */
8 changes: 8 additions & 0 deletions src/config/defaults.h
@@ -0,0 +1,8 @@
#ifndef CONFIG_DEFAULTS_H
#define CONFIG_DEFAULTS_H

#define CONFIG_DEFAULTS(_platform) <config/defaults/_platform.h>

#include CONFIG_DEFAULTS(PLATFORM)

#endif /* CONFIG_DEFAULTS_H */
12 changes: 12 additions & 0 deletions src/config/defaults/pcbios.h
@@ -0,0 +1,12 @@
#ifndef CONFIG_DEFAULTS_PCBIOS_H
#define CONFIG_DEFAULTS_PCBIOS_H

/** @file
*
* Configuration defaults for PCBIOS
*
*/

#define IOAPI_X86

#endif /* CONFIG_DEFAULTS_PCBIOS_H */
12 changes: 12 additions & 0 deletions src/config/ioapi.h
@@ -0,0 +1,12 @@
#ifndef CONFIG_IOAPI_H
#define CONFIG_IOAPI_H

/** @file
*
* I/O API configuration
*
*/

#include <config/defaults.h>

#endif /* CONFIG_IOAPI_H */
82 changes: 82 additions & 0 deletions src/include/gpxe/api.h
@@ -0,0 +1,82 @@
#ifndef _GPXE_API_H
#define _GPXE_API_H

/** @file
*
* gPXE internal APIs
*
* There are various formally-defined APIs internal to gPXE, with
* several differing implementations specific to particular execution
* environments (e.g. PC BIOS, EFI, LinuxBIOS).
*
*/

/** @defgroup Single-implementation APIs
*
* These are APIs for which only a single implementation may be
* compiled in at any given time.
*
* @{
*/

/**
* Calculate function implementation name
*
* @v _prefix Subsystem prefix
* @v _api_func API function
* @ret _subsys_func Subsystem API function
*
* The subsystem prefix should be an empty string for the currently
* selected subsystem, and should be a subsystem-unique string for all
* other subsystems.
*/
#define SINGLE_API_NAME( _prefix, _api_func ) _prefix ## _api_func

/**
* Calculate static inline function name
*
* @v _prefix Subsystem prefix
* @v _api_func API function
* @ret _subsys_func Subsystem API function
*/
#define SINGLE_API_INLINE( _prefix, _api_func ) \
SINGLE_API_NAME ( _prefix, _api_func )

/**
* Provide an API implementation
*
* @v _prefix Subsystem prefix
* @v _api_func API function
* @v _func Implementing function
*/
#define PROVIDE_SINGLE_API( _prefix, _api_func, _func ) \
/* Ensure that _api_func exists */ \
typeof ( _api_func ) _api_func; \
/* Ensure that _func exists */ \
typeof ( _func ) _func; \
/* Ensure that _func is type-compatible with _api_func */ \
typeof ( _api_func ) _func; \
/* Ensure that _subsys_func is non-static */ \
extern typeof ( _api_func ) SINGLE_API_NAME ( _prefix, _api_func ); \
/* Provide symbol alias from _subsys_func to _func */ \
typeof ( _api_func ) SINGLE_API_NAME ( _prefix, _api_func ) \
__attribute__ (( alias ( #_func ) ));

/**
* Provide a static inline API implementation
*
* @v _prefix Subsystem prefix
* @v _api_func API function
*/
#define PROVIDE_SINGLE_API_INLINE( _prefix, _api_func ) \
/* Ensure that _api_func exists */ \
typeof ( _api_func ) _api_func; \
/* Ensure that _subsys_func exists and is static */ \
static typeof ( SINGLE_API_INLINE ( _prefix, _api_func ) ) \
SINGLE_API_INLINE ( _prefix, _api_func ); \
/* Ensure that _subsys_func is type-compatible with _api_func */ \
typeof ( _api_func ) SINGLE_API_INLINE ( _prefix, _api_func );

/** @} */

#endif /* _GPXE_API_H */

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