[ioapi] Formalise the I/O API as used in i386-pcbios

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 */

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 */