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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