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 */
 21struct 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 */
 33size_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 */
 45size_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 */
 56void 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 */
 70u32 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 */
 82void 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 */
103void 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}