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Documentation / misc-devices / c2port.txt




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Based on kernel version 3.15.4. Page generated on 2014-07-07 09:03 EST.

1				C2 port support
2				---------------
3	
4	(C) Copyright 2007 Rodolfo Giometti <giometti@enneenne.com>
5	
6	This program is free software; you can redistribute it and/or modify
7	it under the terms of the GNU General Public License as published by
8	the Free Software Foundation; either version 2 of the License, or
9	(at your option) any later version.
10	
11	This program is distributed in the hope that it will be useful,
12	but WITHOUT ANY WARRANTY; without even the implied warranty of
13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14	GNU General Public License for more details.
15	
16	
17	
18	Overview
19	--------
20	
21	This driver implements the support for Linux of Silicon Labs (Silabs)
22	C2 Interface used for in-system programming of micro controllers.
23	
24	By using this driver you can reprogram the in-system flash without EC2
25	or EC3 debug adapter. This solution is also useful in those systems
26	where the micro controller is connected via special GPIOs pins.
27	
28	References
29	----------
30	
31	The C2 Interface main references are at (http://www.silabs.com)
32	Silicon Laboratories site], see:
33	
34	- AN127: FLASH Programming via the C2 Interface at
35	http://www.silabs.com/Support Documents/TechnicalDocs/an127.pdf 
36	
37	- C2 Specification at
38	http://www.silabs.com/pages/DownloadDoc.aspx?FILEURL=Support%20Documents/TechnicalDocs/an127.pdf&src=SearchResults
39	
40	however it implements a two wire serial communication protocol (bit
41	banging) designed to enable in-system programming, debugging, and
42	boundary-scan testing on low pin-count Silicon Labs devices. Currently
43	this code supports only flash programming but extensions are easy to
44	add.
45	
46	Using the driver
47	----------------
48	
49	Once the driver is loaded you can use sysfs support to get C2port's
50	info or read/write in-system flash.
51	
52	# ls /sys/class/c2port/c2port0/
53	access            flash_block_size  flash_erase       rev_id
54	dev_id            flash_blocks_num  flash_size        subsystem/
55	flash_access      flash_data        reset             uevent
56	
57	Initially the C2port access is disabled since you hardware may have
58	such lines multiplexed with other devices so, to get access to the
59	C2port, you need the command:
60	
61	# echo 1 > /sys/class/c2port/c2port0/access
62	
63	after that you should read the device ID and revision ID of the
64	connected micro controller:
65	
66	# cat /sys/class/c2port/c2port0/dev_id
67	8
68	# cat /sys/class/c2port/c2port0/rev_id
69	1
70	
71	However, for security reasons, the in-system flash access in not
72	enabled yet, to do so you need the command:
73	
74	# echo 1 > /sys/class/c2port/c2port0/flash_access
75	
76	After that you can read the whole flash:
77	
78	# cat /sys/class/c2port/c2port0/flash_data > image
79	
80	erase it:
81	
82	# echo 1 > /sys/class/c2port/c2port0/flash_erase
83	
84	and write it:
85	
86	# cat image > /sys/class/c2port/c2port0/flash_data
87	
88	after writing you have to reset the device to execute the new code:
89	
90	# echo 1 > /sys/class/c2port/c2port0/reset
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