LXR linux/drivers/firmware/arm

   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}
 112