guc_communication_ctb_abi.h

  1/* SPDX-License-Identifier: MIT */
  2/*
  3 * Copyright © 2014-2021 Intel Corporation
  4 */
  5
  6#ifndef _ABI_GUC_COMMUNICATION_CTB_ABI_H
  7#define _ABI_GUC_COMMUNICATION_CTB_ABI_H
  8
  9#include <linux/types.h>
 10#include <linux/build_bug.h>
 11
 12#include "guc_messages_abi.h"
 13
 14/**
 15 * DOC: CT Buffer
 16 *
 17 * Circular buffer used to send `CTB Message`_
 18 */
 19
 20/**
 21 * DOC: CTB Descriptor
 22 *
 23 *  +---+-------+--------------------------------------------------------------+
 24 *  |   | Bits  | Description                                                  |
 25 *  +===+=======+==============================================================+
 26 *  | 0 |  31:0 | **HEAD** - offset (in dwords) to the last dword that was     |
 27 *  |   |       | read from the `CT Buffer`_.                                  |
 28 *  |   |       | It can only be updated by the receiver.                      |
 29 *  +---+-------+--------------------------------------------------------------+
 30 *  | 1 |  31:0 | **TAIL** - offset (in dwords) to the last dword that was     |
 31 *  |   |       | written to the `CT Buffer`_.                                 |
 32 *  |   |       | It can only be updated by the sender.                        |
 33 *  +---+-------+--------------------------------------------------------------+
 34 *  | 2 |  31:0 | **STATUS** - status of the CTB                               |
 35 *  |   |       |                                                              |
 36 *  |   |       |   - _`GUC_CTB_STATUS_NO_ERROR` = 0 (normal operation)        |
 37 *  |   |       |   - _`GUC_CTB_STATUS_OVERFLOW` = 1 (head/tail too large)     |
 38 *  |   |       |   - _`GUC_CTB_STATUS_UNDERFLOW` = 2 (truncated message)      |
 39 *  |   |       |   - _`GUC_CTB_STATUS_MISMATCH` = 4 (head/tail modified)      |
 40 *  +---+-------+--------------------------------------------------------------+
 41 *  |...|       | RESERVED = MBZ                                               |
 42 *  +---+-------+--------------------------------------------------------------+
 43 *  | 15|  31:0 | RESERVED = MBZ                                               |
 44 *  +---+-------+--------------------------------------------------------------+
 45 */
 46
 47struct guc_ct_buffer_desc {
 48	u32 head;
 49	u32 tail;
 50	u32 status;
 51#define GUC_CTB_STATUS_NO_ERROR				0
 52#define GUC_CTB_STATUS_OVERFLOW				(1 << 0)
 53#define GUC_CTB_STATUS_UNDERFLOW			(1 << 1)
 54#define GUC_CTB_STATUS_MISMATCH				(1 << 2)
 55#define GUC_CTB_STATUS_DISABLED				(1 << 3)
 56	u32 reserved[13];
 57} __packed;
 58static_assert(sizeof(struct guc_ct_buffer_desc) == 64);
 59
 60/**
 61 * DOC: CTB Message
 62 *
 63 *  +---+-------+--------------------------------------------------------------+
 64 *  |   | Bits  | Description                                                  |
 65 *  +===+=======+==============================================================+
 66 *  | 0 | 31:16 | **FENCE** - message identifier                               |
 67 *  |   +-------+--------------------------------------------------------------+
 68 *  |   | 15:12 | **FORMAT** - format of the CTB message                       |
 69 *  |   |       |  - _`GUC_CTB_FORMAT_HXG` = 0 - see `CTB HXG Message`_        |
 70 *  |   +-------+--------------------------------------------------------------+
 71 *  |   |  11:8 | **RESERVED**                                                 |
 72 *  |   +-------+--------------------------------------------------------------+
 73 *  |   |   7:0 | **NUM_DWORDS** - length of the CTB message (w/o header)      |
 74 *  +---+-------+--------------------------------------------------------------+
 75 *  | 1 |  31:0 | optional (depends on FORMAT)                                 |
 76 *  +---+-------+                                                              |
 77 *  |...|       |                                                              |
 78 *  +---+-------+                                                              |
 79 *  | n |  31:0 |                                                              |
 80 *  +---+-------+--------------------------------------------------------------+
 81 */
 82
 83#define GUC_CTB_HDR_LEN				1u
 84#define GUC_CTB_MSG_MIN_LEN			GUC_CTB_HDR_LEN
 85#define GUC_CTB_MSG_MAX_LEN			(GUC_CTB_MSG_MIN_LEN + GUC_CTB_MAX_DWORDS)
 86#define GUC_CTB_MSG_0_FENCE			(0xffffu << 16)
 87#define GUC_CTB_MSG_0_FORMAT			(0xfu << 12)
 88#define   GUC_CTB_FORMAT_HXG			0u
 89#define GUC_CTB_MSG_0_RESERVED			(0xfu << 8)
 90#define GUC_CTB_MSG_0_NUM_DWORDS		(0xffu << 0)
 91#define   GUC_CTB_MAX_DWORDS			255
 92
 93/**
 94 * DOC: CTB HXG Message
 95 *
 96 *  +---+-------+--------------------------------------------------------------+
 97 *  |   | Bits  | Description                                                  |
 98 *  +===+=======+==============================================================+
 99 *  | 0 | 31:16 | FENCE                                                        |
100 *  |   +-------+--------------------------------------------------------------+
101 *  |   | 15:12 | FORMAT = GUC_CTB_FORMAT_HXG_                                 |
102 *  |   +-------+--------------------------------------------------------------+
103 *  |   |  11:8 | RESERVED = MBZ                                               |
104 *  |   +-------+--------------------------------------------------------------+
105 *  |   |   7:0 | NUM_DWORDS = length (in dwords) of the embedded HXG message  |
106 *  +---+-------+--------------------------------------------------------------+
107 *  | 1 |  31:0 |                                                              |
108 *  +---+-------+                                                              |
109 *  |...|       | [Embedded `HXG Message`_]                                    |
110 *  +---+-------+                                                              |
111 *  | n |  31:0 |                                                              |
112 *  +---+-------+--------------------------------------------------------------+
113 */
114
115#define GUC_CTB_HXG_MSG_MIN_LEN		(GUC_CTB_MSG_MIN_LEN + GUC_HXG_MSG_MIN_LEN)
116#define GUC_CTB_HXG_MSG_MAX_LEN		GUC_CTB_MSG_MAX_LEN
117
118/**
119 * DOC: CTB based communication
120 *
121 * The CTB (command transport buffer) communication between Host and GuC
122 * is based on u32 data stream written to the shared buffer. One buffer can
123 * be used to transmit data only in one direction (one-directional channel).
124 *
125 * Current status of the each buffer is maintained in the `CTB Descriptor`_.
126 * Each message in data stream is encoded as `CTB HXG Message`_.
127 */
128
129#endif