1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * For transports using message passing.
4  *
5  * Derived from shm.c.
6  *
7  * Copyright (C) 2019-2021 ARM Ltd.
8  * Copyright (C) 2020-2021 OpenSynergy GmbH
9  */
10 
11 #include <linux/types.h>
12 
13 #include "common.h"
14 
15 /*
16  * struct scmi_msg_payld - Transport SDU layout
17  *
18  * The SCMI specification requires all parameters, message headers, return
19  * arguments or any protocol data to be expressed in little endian format only.
20  */
21 struct scmi_msg_payld {
22 	__le32 msg_header;
23 	__le32 msg_payload[];
24 };
25 
26 /**
27  * msg_command_size() - Actual size of transport SDU for command.
28  *
29  * @xfer: message which core has prepared for sending
30  *
31  * Return: transport SDU size.
32  */
msg_command_size(struct scmi_xfer * xfer)33 size_t msg_command_size(struct scmi_xfer *xfer)
34 {
35 	return sizeof(struct scmi_msg_payld) + xfer->tx.len;
36 }
37 
38 /**
39  * msg_response_size() - Maximum size of transport SDU for response.
40  *
41  * @xfer: message which core has prepared for sending
42  *
43  * Return: transport SDU size.
44  */
msg_response_size(struct scmi_xfer * xfer)45 size_t msg_response_size(struct scmi_xfer *xfer)
46 {
47 	return sizeof(struct scmi_msg_payld) + sizeof(__le32) + xfer->rx.len;
48 }
49 
50 /**
51  * msg_tx_prepare() - Set up transport SDU for command.
52  *
53  * @msg: transport SDU for command
54  * @xfer: message which is being sent
55  */
msg_tx_prepare(struct scmi_msg_payld * msg,struct scmi_xfer * xfer)56 void msg_tx_prepare(struct scmi_msg_payld *msg, struct scmi_xfer *xfer)
57 {
58 	msg->msg_header = cpu_to_le32(pack_scmi_header(&xfer->hdr));
59 	if (xfer->tx.buf)
60 		memcpy(msg->msg_payload, xfer->tx.buf, xfer->tx.len);
61 }
62 
63 /**
64  * msg_read_header() - Read SCMI header from transport SDU.
65  *
66  * @msg: transport SDU
67  *
68  * Return: SCMI header
69  */
msg_read_header(struct scmi_msg_payld * msg)70 u32 msg_read_header(struct scmi_msg_payld *msg)
71 {
72 	return le32_to_cpu(msg->msg_header);
73 }
74 
75 /**
76  * msg_fetch_response() - Fetch response SCMI payload from transport SDU.
77  *
78  * @msg: transport SDU with response
79  * @len: transport SDU size
80  * @xfer: message being responded to
81  */
msg_fetch_response(struct scmi_msg_payld * msg,size_t len,struct scmi_xfer * xfer)82 void msg_fetch_response(struct scmi_msg_payld *msg, size_t len,
83 			struct scmi_xfer *xfer)
84 {
85 	size_t prefix_len = sizeof(*msg) + sizeof(msg->msg_payload[0]);
86 
87 	xfer->hdr.status = le32_to_cpu(msg->msg_payload[0]);
88 	xfer->rx.len = min_t(size_t, xfer->rx.len,
89 			     len >= prefix_len ? len - prefix_len : 0);
90 
91 	/* Take a copy to the rx buffer.. */
92 	memcpy(xfer->rx.buf, &msg->msg_payload[1], xfer->rx.len);
93 }
94 
95 /**
96  * msg_fetch_notification() - Fetch notification payload from transport SDU.
97  *
98  * @msg: transport SDU with notification
99  * @len: transport SDU size
100  * @max_len: maximum SCMI payload size to fetch
101  * @xfer: notification message
102  */
msg_fetch_notification(struct scmi_msg_payld * msg,size_t len,size_t max_len,struct scmi_xfer * xfer)103 void msg_fetch_notification(struct scmi_msg_payld *msg, size_t len,
104 			    size_t max_len, struct scmi_xfer *xfer)
105 {
106 	xfer->rx.len = min_t(size_t, max_len,
107 			     len >= sizeof(*msg) ? len - sizeof(*msg) : 0);
108 
109 	/* Take a copy to the rx buffer.. */
110 	memcpy(xfer->rx.buf, msg->msg_payload, xfer->rx.len);
111 }
112