| /** @file |
| I2C Bus Configuration Management Protocol as defined in the PI 1.3 specification. |
| |
| The EFI I2C bus configuration management protocol provides platform specific |
| services that allow the I2C host protocol to reconfigure the switches and multiplexers |
| and set the clock frequency for the I2C bus. This protocol also enables the I2C host protocol |
| to reset an I2C device which may be locking up the I2C bus by holding the clock or data line low. |
| |
| Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR> |
| SPDX-License-Identifier: BSD-2-Clause-Patent |
| |
| @par Revision Reference: |
| This protocol is from PI Version 1.3. |
| |
| **/ |
| |
| #ifndef __I2C_BUS_CONFIGURATION_MANAGEMENT_H__ |
| #define __I2C_BUS_CONFIGURATION_MANAGEMENT_H__ |
| |
| #define EFI_I2C_BUS_CONFIGURATION_MANAGEMENT_PROTOCOL_GUID \ |
| { 0x55b71fb5, 0x17c6, 0x410e, { 0xb5, 0xbd, 0x5f, 0xa2, 0xe3, 0xd4, 0x46, 0x6b }} |
| |
| /// |
| /// I2C bus configuration management protocol |
| /// |
| /// The EFI I2C bus configuration management protocol provides platform |
| /// specific services that allow the I2C host protocol to reconfigure the |
| /// switches and multiplexers and set the clock frequency for the I2C bus. |
| /// This protocol also enables the I2C host protocol to reset an I2C device |
| /// which may be locking up the I2C bus by holding the clock or data line |
| /// low. |
| /// |
| /// The I2C protocol stack uses the concept of an I2C bus configuration as |
| /// a way to describe a particular state of the switches and multiplexers |
| /// in the I2C bus. |
| /// |
| /// A simple I2C bus does not have any multiplexers or switches is described |
| /// to the I2C protocol stack with a single I2C bus configuration which |
| /// specifies the I2C bus frequency. |
| /// |
| /// An I2C bus with switches and multiplexers use an I2C bus configuration |
| /// to describe each of the unique settings for the switches and multiplexers |
| /// and the I2C bus frequency. However the I2C bus configuration management |
| /// protocol only needs to define the I2C bus configurations that the software |
| /// uses, which may be a subset of the total. |
| /// |
| /// The I2C bus configuration description includes a list of I2C devices |
| /// which may be accessed when this I2C bus configuration is enabled. I2C |
| /// devices before a switch or multiplexer must be included in one I2C bus |
| /// configuration while I2C devices after a switch or multiplexer are on |
| /// another I2C bus configuration. |
| /// |
| /// The I2C bus configuration management protocol is an optional protocol. |
| /// When the I2C bus configuration protocol is not defined the I2C host |
| /// protocol does not start and the I2C master protocol may be used for |
| /// other purposes such as SMBus traffic. When the I2C bus configuration |
| /// protocol is available, the I2C host protocol uses the I2C bus |
| /// configuration protocol to call into the platform specific code to set |
| /// the switches and multiplexers and set the maximum I2C bus frequency. |
| /// |
| /// The platform designers determine the maximum I2C bus frequency by |
| /// selecting a frequency which supports all of the I2C devices on the |
| /// I2C bus for the setting of switches and multiplexers. The platform |
| /// designers must validate this against the I2C device data sheets and |
| /// any limits of the I2C controller or bus length. |
| /// |
| /// During I2C device enumeration, the I2C bus driver retrieves the I2C |
| /// bus configuration that must be used to perform I2C transactions to |
| /// each I2C device. This I2C bus configuration value is passed into |
| /// the I2C host protocol to identify the I2C bus configuration required |
| /// to access a specific I2C device. The I2C host protocol calls |
| /// EnableBusConfiguration() to set the switches and multiplexers in the |
| /// I2C bus and the I2C clock frequency. The I2C host protocol may |
| /// optimize calls to EnableBusConfiguration() by only making the call |
| /// when the I2C bus configuration value changes between I2C requests. |
| /// |
| /// When I2C transactions are required on the same I2C bus to change the |
| /// state of multiplexers or switches, the I2C master protocol must be |
| /// used to perform the necessary I2C transactions. |
| /// |
| /// It is up to the platform specific code to choose the proper I2C bus |
| /// configuration when ExitBootServices() is called. Some operating systems |
| /// are not able to manage the I2C bus configurations and must use the I2C |
| /// bus configuration that is established by the platform firmware before |
| /// ExitBootServices() returns. |
| /// |
| typedef struct _EFI_I2C_BUS_CONFIGURATION_MANAGEMENT_PROTOCOL EFI_I2C_BUS_CONFIGURATION_MANAGEMENT_PROTOCOL; |
| |
| |
| /** |
| Enable access to an I2C bus configuration. |
| |
| This routine must be called at or below TPL_NOTIFY. For synchronous |
| requests this routine must be called at or below TPL_CALLBACK. |
| |
| Reconfigure the switches and multiplexers in the I2C bus to enable |
| access to a specific I2C bus configuration. Also select the maximum |
| clock frequency for this I2C bus configuration. |
| |
| This routine uses the I2C Master protocol to perform I2C transactions |
| on the local bus. This eliminates any recursion in the I2C stack for |
| configuration transactions on the same I2C bus. This works because the |
| local I2C bus is idle while the I2C bus configuration is being enabled. |
| |
| If I2C transactions must be performed on other I2C busses, then the |
| EFI_I2C_HOST_PROTOCOL, the EFI_I2C_IO_PROTCOL, or a third party I2C |
| driver interface for a specific device must be used. This requirement |
| is because the I2C host protocol controls the flow of requests to the |
| I2C controller. Use the EFI_I2C_HOST_PROTOCOL when the I2C device is |
| not enumerated by the EFI_I2C_ENUMERATE_PROTOCOL. Use a protocol |
| produced by a third party driver when it is available or the |
| EFI_I2C_IO_PROTOCOL when the third party driver is not available but |
| the device is enumerated with the EFI_I2C_ENUMERATE_PROTOCOL. |
| |
| When Event is NULL, EnableI2cBusConfiguration operates synchronously |
| and returns the I2C completion status as its return value. |
| |
| @param[in] This Pointer to an EFI_I2C_BUS_CONFIGURATION_MANAGEMENT_PROTOCOL |
| structure. |
| @param[in] I2cBusConfiguration Index of an I2C bus configuration. All |
| values in the range of zero to N-1 are |
| valid where N is the total number of I2C |
| bus configurations for an I2C bus. |
| @param[in] Event Event to signal when the transaction is complete |
| @param[out] I2cStatus Buffer to receive the transaction status. |
| |
| @return When Event is NULL, EnableI2cBusConfiguration operates synchrouously |
| and returns the I2C completion status as its return value. In this case it is |
| recommended to use NULL for I2cStatus. The values returned from |
| EnableI2cBusConfiguration are: |
| |
| @retval EFI_SUCCESS The asynchronous bus configuration request |
| was successfully started when Event is not |
| NULL. |
| @retval EFI_SUCCESS The bus configuration request completed |
| successfully when Event is NULL. |
| @retval EFI_DEVICE_ERROR The bus configuration failed. |
| @retval EFI_NO_MAPPING Invalid I2cBusConfiguration value |
| |
| **/ |
| typedef |
| EFI_STATUS |
| (EFIAPI *EFI_I2C_BUS_CONFIGURATION_MANAGEMENT_PROTOCOL_ENABLE_I2C_BUS_CONFIGURATION) ( |
| IN CONST EFI_I2C_BUS_CONFIGURATION_MANAGEMENT_PROTOCOL *This, |
| IN UINTN I2cBusConfiguration, |
| IN EFI_EVENT Event OPTIONAL, |
| IN EFI_STATUS *I2cStatus OPTIONAL |
| ); |
| |
| /// |
| /// I2C bus configuration management protocol |
| /// |
| struct _EFI_I2C_BUS_CONFIGURATION_MANAGEMENT_PROTOCOL { |
| /// |
| /// Enable an I2C bus configuration for use. |
| /// |
| EFI_I2C_BUS_CONFIGURATION_MANAGEMENT_PROTOCOL_ENABLE_I2C_BUS_CONFIGURATION EnableI2cBusConfiguration; |
| }; |
| |
| /// |
| /// Reference to variable defined in the .DEC file |
| /// |
| extern EFI_GUID gEfiI2cBusConfigurationManagementProtocolGuid; |
| |
| #endif // __I2C_BUS_CONFIGURATION_MANAGEMENT_H__ |