I2cMaster.h File Reference

Data Structures
struct	_EFI_I2C_MASTER_PROTOCOL

Macros
#define	EFI_I2C_MASTER_PROTOCOL_GUID   { 0xcd72881f, 0x45b5, 0x4feb, { 0x98, 0xc8, 0x31, 0x3d, 0xa8, 0x11, 0x74, 0x62 }}

Typedefs
typedef struct _EFI_I2C_MASTER_PROTOCOL	EFI_I2C_MASTER_PROTOCOL
typedef IN OUT UINTN *	BusClockHertz
typedef IN UINTN	SlaveAddress
typedef IN UINTN IN EFI_I2C_REQUEST_PACKET *	RequestPacket
typedef IN UINTN IN EFI_I2C_REQUEST_PACKET IN EFI_EVENT	Event
typedef IN UINTN IN EFI_I2C_REQUEST_PACKET IN EFI_EVENT OUT EFI_STATUS *	I2cStatus

Functions
typedef	EFI_STATUS (EFIAPI *EFI_I2C_MASTER_PROTOCOL_SET_BUS_FREQUENCY)(IN CONST EFI_I2C_MASTER_PROTOCOL *This

Variables
EFI_GUID	gEfiI2cMasterProtocolGuid

Detailed Description

I2C Master Protocol as defined in the PI 1.3 specification.

This protocol manipulates the I2C host controller to perform transactions as a master on the I2C bus using the current state of any switches or multiplexers in the I2C bus.

Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.
SPDX-License-Identifier: BSD-2-Clause-Patent

Revision Reference:

This protocol is from PI Version 1.3.

Macro Definition Documentation

#define EFI_I2C_MASTER_PROTOCOL_GUID   { 0xcd72881f, 0x45b5, 0x4feb, { 0x98, 0xc8, 0x31, 0x3d, 0xa8, 0x11, 0x74, 0x62 }}

Typedef Documentation

typedef IN OUT UINTN* BusClockHertz

typedef struct _EFI_I2C_MASTER_PROTOCOL EFI_I2C_MASTER_PROTOCOL

typedef IN UINTN IN EFI_I2C_REQUEST_PACKET IN EFI_EVENT Event

typedef IN UINTN IN EFI_I2C_REQUEST_PACKET IN EFI_EVENT OUT EFI_STATUS* I2cStatus

typedef IN UINTN IN EFI_I2C_REQUEST_PACKET* RequestPacket

typedef IN UINTN SlaveAddress

Function Documentation

typedef EFI_STATUS

(

EFIAPI *

EFI_I2C_MASTER_PROTOCOL_START_REQUEST

)

Set the frequency for the I2C clock line.

This routine must be called at or below TPL_NOTIFY.

The software and controller do a best case effort of using the specified frequency for the I2C bus. If the frequency does not match exactly then the I2C master protocol selects the next lower frequency to avoid exceeding the operating conditions for any of the I2C devices on the bus. For example if 400 KHz was specified and the controller's divide network only supports 402 KHz or 398 KHz then the I2C master protocol selects 398 KHz. If there are not lower frequencies available, then return EFI_UNSUPPORTED.

Parameters

[in]	This	Pointer to an EFI_I2C_MASTER_PROTOCOL structure
[in]	BusClockHertz	Pointer to the requested I2C bus clock frequency in Hertz. Upon return this value contains the actual frequency in use by the I2C controller.

Return values

EFI_SUCCESS	The bus frequency was set successfully.
EFI_ALREADY_STARTED	The controller is busy with another transaction.
EFI_INVALID_PARAMETER	BusClockHertz is NULL
EFI_UNSUPPORTED	The controller does not support this frequency.

Reset the I2C controller and configure it for use

This routine must be called at or below TPL_NOTIFY.

The I2C controller is reset. The caller must call SetBusFrequench() after calling Reset().

Parameters

[in]

This

Pointer to an EFI_I2C_MASTER_PROTOCOL structure.

Return values

EFI_SUCCESS	The reset completed successfully.
EFI_ALREADY_STARTED	The controller is busy with another transaction.
EFI_DEVICE_ERROR	The reset operation failed.

Start an I2C transaction on the host controller.

This routine must be called at or below TPL_NOTIFY. For synchronous requests this routine must be called at or below TPL_CALLBACK.

This function initiates an I2C transaction on the controller. To enable proper error handling by the I2C protocol stack, the I2C master protocol does not support queuing but instead only manages one I2C transaction at a time. This API requires that the I2C bus is in the correct configuration for the I2C transaction.

The transaction is performed by sending a start-bit and selecting the I2C device with the specified I2C slave address and then performing the specified I2C operations. When multiple operations are requested they are separated with a repeated start bit and the slave address. The transaction is terminated with a stop bit.

When Event is NULL, StartRequest operates synchronously and returns the I2C completion status as its return value.

When Event is not NULL, StartRequest synchronously returns EFI_SUCCESS indicating that the I2C transaction was started asynchronously. The transaction status value is returned in the buffer pointed to by I2cStatus upon the completion of the I2C transaction when I2cStatus is not NULL. After the transaction status is returned the Event is signaled.

Note: The typical consumer of this API is the I2C host protocol. Extreme care must be taken by other consumers of this API to prevent confusing the third party I2C drivers due to a state change at the I2C device which the third party I2C drivers did not initiate. I2C platform specific code may use this API within these guidelines.

Parameters

[in]	This	Pointer to an EFI_I2C_MASTER_PROTOCOL structure.
[in]	SlaveAddress	Address of the device on the I2C bus. Set the I2C_ADDRESSING_10_BIT when using 10-bit addresses, clear this bit for 7-bit addressing. Bits 0-6 are used for 7-bit I2C slave addresses and bits 0-9 are used for 10-bit I2C slave addresses.
[in]	RequestPacket	Pointer to an EFI_I2C_REQUEST_PACKET structure describing the I2C transaction.
[in]	Event	Event to signal for asynchronous transactions, NULL for asynchronous transactions
[out]	I2cStatus	Optional buffer to receive the I2C transaction completion status

Return values

EFI_SUCCESS	The asynchronous transaction was successfully started when Event is not NULL.
EFI_SUCCESS	The transaction completed successfully when Event is NULL.
EFI_ALREADY_STARTED	The controller is busy with another transaction.
EFI_BAD_BUFFER_SIZE	The RequestPacket->LengthInBytes value is too large.
EFI_DEVICE_ERROR	There was an I2C error (NACK) during the transaction.
EFI_INVALID_PARAMETER	RequestPacket is NULL
EFI_NOT_FOUND	Reserved bit set in the SlaveAddress parameter
EFI_NO_RESPONSE	The I2C device is not responding to the slave address. EFI_DEVICE_ERROR will be returned if the controller cannot distinguish when the NACK occurred.
EFI_OUT_OF_RESOURCES	Insufficient memory for I2C transaction
EFI_UNSUPPORTED	The controller does not support the requested transaction.

Variable Documentation

EFI_GUID gEfiI2cMasterProtocolGuid