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/* SPDX-License-Identifier: MIT */
/*
* Copyright © 2014-2021 Intel Corporation
*/
#ifndef _ABI_GUC_COMMUNICATION_MMIO_ABI_H
#define _ABI_GUC_COMMUNICATION_MMIO_ABI_H
/**
* DOC: MMIO based communication
*
* The MMIO based communication between Host and GuC uses software scratch
* registers, where first register holds data treated as message header,
* and other registers are used to hold message payload.
*
* For Gen9+, GuC uses software scratch registers 0xC180-0xC1B8,
* but no H2G command takes more than 8 parameters and the GuC FW
* itself uses an 8-element array to store the H2G message.
*
* +-----------+---------+---------+---------+
* | MMIO[0] | MMIO[1] | ... | MMIO[n] |
* +-----------+---------+---------+---------+
* | header | optional payload |
* +======+====+=========+=========+=========+
* | 31:28|type| | | |
* +------+----+ | | |
* | 27:16|data| | | |
* +------+----+ | | |
* | 15:0|code| | | |
* +------+----+---------+---------+---------+
*
* The message header consists of:
*
* - **type**, indicates message type
* - **code**, indicates message code, is specific for **type**
* - **data**, indicates message data, optional, depends on **code**
*
* The following message **types** are supported:
*
* - **REQUEST**, indicates Host-to-GuC request, requested GuC action code
* must be priovided in **code** field. Optional action specific parameters
* can be provided in remaining payload registers or **data** field.
*
* - **RESPONSE**, indicates GuC-to-Host response from earlier GuC request,
* action response status will be provided in **code** field. Optional
* response data can be returned in remaining payload registers or **data**
* field.
*/
#define GUC_MAX_MMIO_MSG_LEN 8
#endif /* _ABI_GUC_COMMUNICATION_MMIO_ABI_H */
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