1 #ifndef __src_common_shared_msgq_inc_msgq_msgq_priv_h__ 2 #define __src_common_shared_msgq_inc_msgq_msgq_priv_h__ 3 4 /* Excerpt of RM headers from https://github.com/NVIDIA/open-gpu-kernel-modules/tree/535.113.01 */ 5 6 /* 7 * SPDX-FileCopyrightText: Copyright (c) 2018-2019 NVIDIA CORPORATION & AFFILIATES. All rights reserved. 8 * SPDX-License-Identifier: MIT 9 * 10 * Permission is hereby granted, free of charge, to any person obtaining a 11 * copy of this software and associated documentation files (the "Software"), 12 * to deal in the Software without restriction, including without limitation 13 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 14 * and/or sell copies of the Software, and to permit persons to whom the 15 * Software is furnished to do so, subject to the following conditions: 16 * 17 * The above copyright notice and this permission notice shall be included in 18 * all copies or substantial portions of the Software. 19 * 20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 21 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 22 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 23 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 24 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 25 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 26 * DEALINGS IN THE SOFTWARE. 27 */ 28 29 /** 30 * msgqTxHeader -- TX queue data structure 31 * @version: the version of this structure, must be 0 32 * @size: the size of the entire queue, including this header 33 * @msgSize: the padded size of queue element, 16 is minimum 34 * @msgCount: the number of elements in this queue 35 * @writePtr: head index of this queue 36 * @flags: 1 = swap the RX pointers 37 * @rxHdrOff: offset of readPtr in this structure 38 * @entryOff: offset of beginning of queue (msgqRxHeader), relative to 39 * beginning of this structure 40 * 41 * The command queue is a queue of RPCs that are sent from the driver to the 42 * GSP. The status queue is a queue of messages/responses from GSP-RM to the 43 * driver. Although the driver allocates memory for both queues, the command 44 * queue is owned by the driver and the status queue is owned by GSP-RM. In 45 * addition, the headers of the two queues must not share the same 4K page. 46 * 47 * Each queue is prefixed with this data structure. The idea is that a queue 48 * and its header are written to only by their owner. That is, only the 49 * driver writes to the command queue and command queue header, and only the 50 * GSP writes to the status (receive) queue and its header. 51 * 52 * This is enforced by the concept of "swapping" the RX pointers. This is 53 * why the 'flags' field must be set to 1. 'rxHdrOff' is how the GSP knows 54 * where the where the tail pointer of its status queue. 55 * 56 * When the driver writes a new RPC to the command queue, it updates writePtr. 57 * When it reads a new message from the status queue, it updates readPtr. In 58 * this way, the GSP knows when a new command is in the queue (it polls 59 * writePtr) and it knows how much free space is in the status queue (it 60 * checks readPtr). The driver never cares about how much free space is in 61 * the status queue. 62 * 63 * As usual, producers write to the head pointer, and consumers read from the 64 * tail pointer. When head == tail, the queue is empty. 65 * 66 * So to summarize: 67 * command.writePtr = head of command queue 68 * command.readPtr = tail of status queue 69 * status.writePtr = head of status queue 70 * status.readPtr = tail of command queue 71 */ 72 typedef struct 73 { 74 NvU32 version; // queue version 75 NvU32 size; // bytes, page aligned 76 NvU32 msgSize; // entry size, bytes, must be power-of-2, 16 is minimum 77 NvU32 msgCount; // number of entries in queue 78 NvU32 writePtr; // message id of next slot 79 NvU32 flags; // if set it means "i want to swap RX" 80 NvU32 rxHdrOff; // Offset of msgqRxHeader from start of backing store. 81 NvU32 entryOff; // Offset of entries from start of backing store. 82 } msgqTxHeader; 83 84 /** 85 * msgqRxHeader - RX queue data structure 86 * @readPtr: tail index of the other queue 87 * 88 * Although this is a separate struct, it could easily be merged into 89 * msgqTxHeader. msgqTxHeader.rxHdrOff is simply the offset of readPtr 90 * from the beginning of msgqTxHeader. 91 */ 92 typedef struct 93 { 94 NvU32 readPtr; // message id of last message read 95 } msgqRxHeader; 96 97 #endif 98