Port I/O

I/O port operations and reservations. More...

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Detailed Description

I/O port operations and reservations.

The CPU can communicate with certain hardware through I/O ports, these ports are accessed using special opcodes.

Reserving I/O Ports

To avoid conflicts between different subsystems or drivers trying to use the same I/O ports, we provide a simple reservation mechanism. Before a range of I/O ports is used, it should be reserved using io_reserve(). Once the ports are no longer needed, they should be released using io_release().

There is no strict enforcement of I/O port reservations at the hardware level, so we have no choice but to hope that everyone is on their best behaviour.

Macros
#define	IO_PORT_MAX   UINT16_MAX
	Maximum I/O port number.

Typedefs
typedef uint16_t	port_t
	I/O port type.

Functions
uint64_t	io_reserve (port_t *out, port_t minBase, port_t maxBase, uint64_t alignment, uint64_t length, const char *owner)
	Find and reserve a range of I/O ports if available.
void	io_release (port_t base, uint64_t length)
	Release a previously reserved range of I/O ports.
static void	io_out8 (port_t port, uint8_t val)
	Write an 8-bit value to an I/O port.
static uint8_t	io_in8 (port_t port)
	Read an 8-bit value from an I/O port.
static void	io_out16 (port_t port, uint16_t val)
	Write a 16-bit value to an I/O port.
static uint16_t	io_in16 (port_t port)
	Read a 16-bit value from an I/O port.
static uint32_t	io_in32 (port_t port)
	Write a 32-bit value to an I/O port.
static void	io_out32 (port_t port, uint32_t val)
	Read a 32-bit value from an I/O port.

Macro Definition Documentation

IO_PORT_MAX

#define IO_PORT_MAX   UINT16_MAX

Maximum I/O port number.

Definition at line 32 of file io.h.

Typedef Documentation

port_t

typedef uint16_t port_t

I/O port type.

Definition at line 27 of file io.h.

Function Documentation

io_reserve()

uint64_t io_reserve	(	port_t *	out,
		port_t	minBase,
		port_t	maxBase,
		uint64_t	alignment,
		uint64_t	length,
		const char *	owner
	)

Find and reserve a range of I/O ports if available.

Note

The minBase and maxBase do NOT specify the exact range to reserve, but rather the minimum and maximum values for the starting port of the range to reserve. For example, the minimum range would be [minBase, minBase + length) and the maximum range would be [maxBase, maxBase + length).

Todo:

Find a way to store the owner of each reservation that does not use way to much memory, and isent super slow.

Parameters

out	Output pointer for the first reserved port.
minBase	The minimum base I/O port address.
maxBase	The maximum base I/O port address.
alignment	The alignment of the I/O ports to reserve.
length	The amount of contiguous I/O ports to reserve.
owner	A string identifying the owner of the reservation, for debugging purposes, can be NULL.

Returns

On success, 0. On failure, ERR and errno is set to:

• EINVAL: Invalid parameters.
• EOVERFLOW: The requested range overflows.
• ENOSPC: No suitable range of I/O ports available.

Definition at line 15 of file io.c.

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io_release()

void io_release	(	port_t	base,
		uint64_t	length
	)

Release a previously reserved range of I/O ports.

Parameters

base	The base I/O port address of the reserved range.
length	The amount of contiguous I/O ports to release.

Definition at line 43 of file io.c.

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io_out8()

static void io_out8 ( port_t  port, uint8_t  val  )

inlinestatic

Write an 8-bit value to an I/O port.

Parameters

port	The I/O port to write to.
val	The value to write.

Definition at line 71 of file io.h.

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io_in8()

static uint8_t io_in8 ( port_t  port )

inlinestatic

Read an 8-bit value from an I/O port.

Parameters

port	The I/O port to read from.

Returns

The value read from the port.

Definition at line 82 of file io.h.

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io_out16()

static void io_out16 ( port_t  port, uint16_t  val  )

inlinestatic

Write a 16-bit value to an I/O port.

Parameters

port	The I/O port to write to.
val	The value to write.

Definition at line 95 of file io.h.

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io_in16()

static uint16_t io_in16 ( port_t  port )

inlinestatic

Read a 16-bit value from an I/O port.

Parameters

port	The I/O port to read from.

Returns

The value read from the port.

Definition at line 106 of file io.h.

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io_in32()

static uint32_t io_in32 ( port_t  port )

inlinestatic

Write a 32-bit value to an I/O port.

Parameters

port	The I/O port to write to.
val	The value to write.

Definition at line 119 of file io.h.

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io_out32()

static void io_out32 ( port_t  port, uint32_t  val  )

inlinestatic

Read a 32-bit value from an I/O port.

Parameters

port	The I/O port to read from.

Returns

The value read from the port.

Definition at line 132 of file io.h.

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