1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * For transports using message passing. 4 * 5 * Derived from shm.c. 6 * 7 * Copyright (C) 2019-2024 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 */ 33 static 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 */ 45 static 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 */ 56 static 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 */ 70 static 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 */ 82 static void msg_fetch_response(struct scmi_msg_payld *msg, 83 size_t len, 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 */ 103 static 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 } 112 113 static const struct scmi_message_operations scmi_msg_ops = { 114 .tx_prepare = msg_tx_prepare, 115 .command_size = msg_command_size, 116 .response_size = msg_response_size, 117 .read_header = msg_read_header, 118 .fetch_response = msg_fetch_response, 119 .fetch_notification = msg_fetch_notification, 120 }; 121 122 const struct scmi_message_operations *scmi_message_operations_get(void) 123 { 124 return &scmi_msg_ops; 125 } 126