#!/usr/bin/env python3
#
# Copyright (c) 2019 Intel Corporation
#
# SPDX-License-Identifier: Apache-2.0
#
# Author: Sathish Kuttan <sathish.k.kuttan@intel.com>

# This script is the top level script that an user can invoke to
# download a Zephyr application binary from a Linux host connected
# over SPI to Intel Sue Creek S1000 target during development.

import os
import sys
import hashlib
import device
import messenger

sue_creek = device.Device()
msg = messenger.Message()

def check_arguments():
    """
    Check whether file name is provided.
    If not print usage instruction and exit.
    """
    if len(sys.argv) != 2:
        print('Usage: python3 %s <zephyr.bin>' % sys.argv[0])
        sys.exit()
    return sys.argv[1]

def calc_firmware_sha(file):
    """
    Open firmware image file and calculate file size
    Pad file size to a multiple of 64 bytes
    Calculate SHA256 hash of the padded contents
    """
    with open(file, 'rb') as firmware:
        firmware.seek(0, 2)
        size = firmware.tell()

        # pad firmware to round upto 64 byte boundary
        padding = (size % 64)
        if padding != 0:
            padding = (64 - padding)
        size += padding

        firmware.seek(0, 0)
        sha256 = hashlib.sha256()
        for block in iter(lambda: firmware.read(4096), b""):
            sha256.update(block)
        firmware.close()

        if padding != 0:
            sha256.update(b'\0' * padding)
            print('Firmware (%s): %d bytes, will be padded to %d bytes.'
                    % (os.path.basename(file), size - padding, size))
        else:
            print('Firmware file size: %d bytes.' % size)
        print('SHA: ' + sha256.hexdigest())
        return (size, padding, sha256.digest())

def setup_device():
    """
    Configure SPI master device
    Reset target and send initialization commands
    """
    sue_creek.configure_device(spi_mode=3, order='msb', bits=8)
    sue_creek.reset_device()

    command = msg.create_memwrite_cmd((0x71d14, 0, 0x71d24, 0,
            0x304628, 0xd, 0x71fd0, 0x3))
    response = sue_creek.send_receive(command)
    msg.print_response(response)

def load_firmware(file, size, padding, sha):
    """
    Send command to load firmware
    Transfer binary file contents including padding
    """
    command = msg.create_loadfw_cmd(size, sha)
    response = sue_creek.send_receive(command)
    msg.print_response(response)

    with open(file, 'rb') as firmware:
        firmware.seek(0, 0)
        block_size = msg.get_bulk_message_size()
        transferred = 0
        for block in iter(lambda: firmware.read(block_size), b""):
            if len(block) < block_size:
                block += b'\0' * padding
            bulk_msg = msg.create_bulk_message(block)
            sue_creek.send_bulk(bulk_msg)
            transferred += len(bulk_msg)
            sys.stdout.write('\r%d of %d bytes transferred to %s.'
                    % (transferred, size, sue_creek.name))
        print('')
        firmware.close()

    sue_creek.check_device_ready()

    command = msg.create_null_cmd()
    response = sue_creek.send_receive(command)
    msg.print_response(response)

def execute_firmware():
    """
    Send command to start execution
    """
    command = msg.create_memwrite_cmd((0x71d10, 0, 0x71d20, 0))
    response = sue_creek.send_receive(command)
    msg.print_response(response)

    command = msg.create_execfw_cmd()
    response = sue_creek.send_receive(command, wait=False)
    msg.print_response(response)

def main():
    """
    Check arguments to ensure binary file is provided.
    Calculate SHA of the binary image
    Setup the SPI master device and GPIOs on the host
    Download Firmware
    """
    file = check_arguments()
    (size, padding, sha) = calc_firmware_sha(file)
    setup_device()
    load_firmware(file, size, padding, sha)
    execute_firmware()
    sue_creek.close()

if __name__ == '__main__':
    main()