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#ifndef __src_common_shared_msgq_inc_msgq_msgq_priv_h__
#define __src_common_shared_msgq_inc_msgq_msgq_priv_h__
/* Excerpt of RM headers from https://github.com/NVIDIA/open-gpu-kernel-modules/tree/535.113.01 */
/*
* SPDX-FileCopyrightText: Copyright (c) 2018-2019 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
* SPDX-License-Identifier: MIT
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
/**
* msgqTxHeader -- TX queue data structure
* @version: the version of this structure, must be 0
* @size: the size of the entire queue, including this header
* @msgSize: the padded size of queue element, 16 is minimum
* @msgCount: the number of elements in this queue
* @writePtr: head index of this queue
* @flags: 1 = swap the RX pointers
* @rxHdrOff: offset of readPtr in this structure
* @entryOff: offset of beginning of queue (msgqRxHeader), relative to
* beginning of this structure
*
* The command queue is a queue of RPCs that are sent from the driver to the
* GSP. The status queue is a queue of messages/responses from GSP-RM to the
* driver. Although the driver allocates memory for both queues, the command
* queue is owned by the driver and the status queue is owned by GSP-RM. In
* addition, the headers of the two queues must not share the same 4K page.
*
* Each queue is prefixed with this data structure. The idea is that a queue
* and its header are written to only by their owner. That is, only the
* driver writes to the command queue and command queue header, and only the
* GSP writes to the status (receive) queue and its header.
*
* This is enforced by the concept of "swapping" the RX pointers. This is
* why the 'flags' field must be set to 1. 'rxHdrOff' is how the GSP knows
* where the where the tail pointer of its status queue.
*
* When the driver writes a new RPC to the command queue, it updates writePtr.
* When it reads a new message from the status queue, it updates readPtr. In
* this way, the GSP knows when a new command is in the queue (it polls
* writePtr) and it knows how much free space is in the status queue (it
* checks readPtr). The driver never cares about how much free space is in
* the status queue.
*
* As usual, producers write to the head pointer, and consumers read from the
* tail pointer. When head == tail, the queue is empty.
*
* So to summarize:
* command.writePtr = head of command queue
* command.readPtr = tail of status queue
* status.writePtr = head of status queue
* status.readPtr = tail of command queue
*/
typedef struct
{
NvU32 version; // queue version
NvU32 size; // bytes, page aligned
NvU32 msgSize; // entry size, bytes, must be power-of-2, 16 is minimum
NvU32 msgCount; // number of entries in queue
NvU32 writePtr; // message id of next slot
NvU32 flags; // if set it means "i want to swap RX"
NvU32 rxHdrOff; // Offset of msgqRxHeader from start of backing store.
NvU32 entryOff; // Offset of entries from start of backing store.
} msgqTxHeader;
/**
* msgqRxHeader - RX queue data structure
* @readPtr: tail index of the other queue
*
* Although this is a separate struct, it could easily be merged into
* msgqTxHeader. msgqTxHeader.rxHdrOff is simply the offset of readPtr
* from the beginning of msgqTxHeader.
*/
typedef struct
{
NvU32 readPtr; // message id of last message read
} msgqRxHeader;
#endif
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