0001 .. SPDX-License-Identifier: GPL-2.0
0002 .. include:: <isonum.txt>
0003
0004 ===============
0005 C2 port support
0006 ===============
0007
0008 (C) Copyright 2007 Rodolfo Giometti <giometti@enneenne.com>
0009
0010 This program is free software; you can redistribute it and/or modify
0011 it under the terms of the GNU General Public License as published by
0012 the Free Software Foundation; either version 2 of the License, or
0013 (at your option) any later version.
0014
0015 This program is distributed in the hope that it will be useful,
0016 but WITHOUT ANY WARRANTY; without even the implied warranty of
0017 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
0018 GNU General Public License for more details.
0019
0020
0021
0022 Overview
0023 --------
0024
0025 This driver implements the support for Linux of Silicon Labs (Silabs)
0026 C2 Interface used for in-system programming of micro controllers.
0027
0028 By using this driver you can reprogram the in-system flash without EC2
0029 or EC3 debug adapter. This solution is also useful in those systems
0030 where the micro controller is connected via special GPIOs pins.
0031
0032 References
0033 ----------
0034
0035 The C2 Interface main references are at (https://www.silabs.com)
0036 Silicon Laboratories site], see:
0037
0038 - AN127: FLASH Programming via the C2 Interface at
0039 https://www.silabs.com/Support Documents/TechnicalDocs/an127.pdf
0040
0041 - C2 Specification at
0042 https://www.silabs.com/pages/DownloadDoc.aspx?FILEURL=Support%20Documents/TechnicalDocs/an127.pdf&src=SearchResults
0043
0044 however it implements a two wire serial communication protocol (bit
0045 banging) designed to enable in-system programming, debugging, and
0046 boundary-scan testing on low pin-count Silicon Labs devices. Currently
0047 this code supports only flash programming but extensions are easy to
0048 add.
0049
0050 Using the driver
0051 ----------------
0052
0053 Once the driver is loaded you can use sysfs support to get C2port's
0054 info or read/write in-system flash::
0055
0056 # ls /sys/class/c2port/c2port0/
0057 access flash_block_size flash_erase rev_id
0058 dev_id flash_blocks_num flash_size subsystem/
0059 flash_access flash_data reset uevent
0060
0061 Initially the C2port access is disabled since you hardware may have
0062 such lines multiplexed with other devices so, to get access to the
0063 C2port, you need the command::
0064
0065 # echo 1 > /sys/class/c2port/c2port0/access
0066
0067 after that you should read the device ID and revision ID of the
0068 connected micro controller::
0069
0070 # cat /sys/class/c2port/c2port0/dev_id
0071 8
0072 # cat /sys/class/c2port/c2port0/rev_id
0073 1
0074
0075 However, for security reasons, the in-system flash access in not
0076 enabled yet, to do so you need the command::
0077
0078 # echo 1 > /sys/class/c2port/c2port0/flash_access
0079
0080 After that you can read the whole flash::
0081
0082 # cat /sys/class/c2port/c2port0/flash_data > image
0083
0084 erase it::
0085
0086 # echo 1 > /sys/class/c2port/c2port0/flash_erase
0087
0088 and write it::
0089
0090 # cat image > /sys/class/c2port/c2port0/flash_data
0091
0092 after writing you have to reset the device to execute the new code::
0093
0094 # echo 1 > /sys/class/c2port/c2port0/reset
