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147 lines
6.3 KiB
C
147 lines
6.3 KiB
C
/** @file
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I2C Host Protocol as defined in the PI 1.3 specification.
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This protocol provides callers with the ability to do I/O transactions
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to all of the devices on the I2C bus.
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Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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@par Revision Reference:
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This protocol is from PI Version 1.3.
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**/
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#ifndef __I2C_HOST_H__
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#define __I2C_HOST_H__
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#include <Pi/PiI2c.h>
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#define EFI_I2C_HOST_PROTOCOL_GUID { 0xa5aab9e3, 0xc727, 0x48cd, { 0x8b, 0xbf, 0x42, 0x72, 0x33, 0x85, 0x49, 0x48 }}
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///
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/// I2C Host Protocol
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///
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/// The I2C bus driver uses the services of the EFI_I2C_HOST_PROTOCOL
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/// to produce an instance of the EFI_I2C_IO_PROTOCOL for each I2C
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/// device on an I2C bus.
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///
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/// The EFI_I2C_HOST_PROTOCOL exposes an asynchronous interface to
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/// callers to perform transactions to any device on the I2C bus.
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/// Internally, the I2C host protocol manages the flow of the I2C
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/// transactions to the host controller, keeping them in FIFO order.
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/// Prior to each transaction, the I2C host protocol ensures that the
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/// switches and multiplexers are properly configured. The I2C host
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/// protocol then starts the transaction on the host controller using
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/// the EFI_I2C_MASTER_PROTOCOL.
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///
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typedef struct _EFI_I2C_HOST_PROTOCOL EFI_I2C_HOST_PROTOCOL;
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/**
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Queue an I2C transaction for execution on the I2C controller.
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This routine must be called at or below TPL_NOTIFY. For
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synchronous requests this routine must be called at or below
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TPL_CALLBACK.
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The I2C host protocol uses the concept of I2C bus configurations
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to describe the I2C bus. An I2C bus configuration is defined as
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a unique setting of the multiplexers and switches in the I2C bus
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which enable access to one or more I2C devices. When using a
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switch to divide a bus, due to bus frequency differences, the
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I2C bus configuration management protocol defines an I2C bus
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configuration for the I2C devices on each side of the switch.
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When using a multiplexer, the I2C bus configuration management
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defines an I2C bus configuration for each of the selector values
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required to control the multiplexer. See Figure 1 in the I2C -bus
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specification and user manual for a complex I2C bus configuration.
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The I2C host protocol processes all transactions in FIFO order.
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Prior to performing the transaction, the I2C host protocol calls
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EnableI2cBusConfiguration to reconfigure the switches and
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multiplexers in the I2C bus enabling access to the specified I2C
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device. The EnableI2cBusConfiguration also selects the I2C bus
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frequency for the I2C device. After the I2C bus is configured,
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the I2C host protocol calls the I2C master protocol to start the
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I2C transaction.
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When Event is NULL, QueueRequest() operates synchronously and
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returns the I2C completion status as its return value.
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When Event is not NULL, QueueRequest() synchronously returns
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EFI_SUCCESS indicating that the asynchronously I2C transaction was
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queued. The values above are returned in the buffer pointed to by
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I2cStatus upon the completion of the I2C transaction when I2cStatus
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is not NULL.
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@param[in] This Pointer to an EFI_I2C_HOST_PROTOCOL structure.
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@param[in] I2cBusConfiguration I2C bus configuration to access the I2C
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device
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@param[in] SlaveAddress Address of the device on the I2C bus. Set
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the I2C_ADDRESSING_10_BIT when using 10-bit
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addresses, clear this bit for 7-bit addressing.
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Bits 0-6 are used for 7-bit I2C slave addresses
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and bits 0-9 are used for 10-bit I2C slave
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addresses.
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@param[in] Event Event to signal for asynchronous transactions,
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NULL for synchronous transactions
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@param[in] RequestPacket Pointer to an EFI_I2C_REQUEST_PACKET structure
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describing the I2C transaction
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@param[out] I2cStatus Optional buffer to receive the I2C transaction
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completion status
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@retval EFI_SUCCESS The asynchronous transaction was successfully
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queued when Event is not NULL.
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@retval EFI_SUCCESS The transaction completed successfully when
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Event is NULL.
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@retval EFI_BAD_BUFFER_SIZE The RequestPacket->LengthInBytes value is
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too large.
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@retval EFI_DEVICE_ERROR There was an I2C error (NACK) during the
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transaction.
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@retval EFI_INVALID_PARAMETER RequestPacket is NULL
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@retval EFI_NOT_FOUND Reserved bit set in the SlaveAddress parameter
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@retval EFI_NO_MAPPING Invalid I2cBusConfiguration value
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@retval EFI_NO_RESPONSE The I2C device is not responding to the slave
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address. EFI_DEVICE_ERROR will be returned
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if the controller cannot distinguish when the
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NACK occurred.
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@retval EFI_OUT_OF_RESOURCES Insufficient memory for I2C transaction
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@retval EFI_UNSUPPORTED The controller does not support the requested
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transaction.
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**/
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typedef
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EFI_STATUS
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(EFIAPI *EFI_I2C_HOST_PROTOCOL_QUEUE_REQUEST) (
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IN CONST EFI_I2C_HOST_PROTOCOL *This,
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IN UINTN I2cBusConfiguration,
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IN UINTN SlaveAddress,
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IN EFI_EVENT Event OPTIONAL,
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IN EFI_I2C_REQUEST_PACKET *RequestPacket,
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OUT EFI_STATUS *I2cStatus OPTIONAL
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);
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///
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/// I2C Host Protocol
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///
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struct _EFI_I2C_HOST_PROTOCOL {
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///
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/// Queue an I2C transaction for execution on the I2C bus
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///
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EFI_I2C_HOST_PROTOCOL_QUEUE_REQUEST QueueRequest;
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///
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/// Pointer to an EFI_I2C_CONTROLLER_CAPABILITIES data structure
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/// containing the capabilities of the I2C host controller.
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///
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CONST EFI_I2C_CONTROLLER_CAPABILITIES *I2cControllerCapabilities;
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};
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///
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/// Reference to variable defined in the .DEC file
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///
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extern EFI_GUID gEfiI2cHostProtocolGuid;
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#endif // __I2C_HOST_H__
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