Documentation/i2c/slave-testunit-backend.rst

1 .. SPDX-License-Identifier: GPL-2.0
7 by Wolfram Sang <wsa@sang-engineering.com> in 2020
11 easy to obtain). Examples include multi-master testing, and SMBus Host Notify
21 # echo "slave-testunit 0x1030" > /sys/bus/i2c/devices/i2c-0/new_device
23 After that, you will have a write-only device listening. Reads will just return
24 an 8-bit version number of the testunit. When writing, the device consists of 4
25 8-bit registers and, except for some "partial" commands, all registers must be
29 0x00 CMD   - which test to trigger
30 0x01 DATAL - configuration byte 1 for the test
31 0x02 DATAH - configuration byte 2 for the test
32 0x03 DELAY - delay in n * 10ms until test is started
34 Using 'i2cset' from the i2c-tools package, the generic command looks like:
36 # i2cset -y <bus_num> <testunit_address> <CMD> <DATAL> <DATAH> <DELAY> i
46 --------
51    DATAL - address to read data from (lower 7 bits, highest bit currently unused)
52    DATAH - number of bytes to read
54 This is useful to test if your bus master driver is handling multi-master
60 # i2cset -y 0 0x30 0x01 0x50 0x80 0x05 i
63    DATAL - low byte of the status word to send
64    DATAH - high byte of the status word to send
67 status word is currently ignored in the Linux Kernel. Example to send a
70 # i2cset -y 0 0x30 0x02 0x42 0x64 0x01 i
73    DATAL - must be '1', i.e. one further byte will be written
74    DATAH - number of bytes to be sent back
75    DELAY - not applicable, partial command!
83 data consists of the length first, and then of an array of bytes from length-1
85 i2ctransfer (you need i2c-tools v4.2 or later):
87 # i2ctransfer -y 0 w3@0x30 0x03 0x01 0x10 r?