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
30 		compatible = "slave-testunit";
39 When writing, the device consists of 4 8-bit registers and, except for some
43 .. csv-table::
49   0x03, DELAY, delay in n * 10ms until test is started
51 Using 'i2cset' from the i2c-tools package, the generic command looks like::
53   # i2cset -y <bus_num> <testunit_address> <CMD> <DATAL> <DATAH> <DELAY> i
55 DELAY is a generic parameter which will delay the execution of the test in CMD.
56 While a command is running (including the delay), new commands will not be
63 --------
73 .. list-table::
74   :header-rows: 1
76   * - CMD
77     - DATAL
78     - DATAH
79     - DELAY
81   * - 0x01
82     - address to read data from (lower 7 bits, highest bit currently unused)
83     - number of bytes to read
84     - n * 10ms
87 handling multi-master correctly. You can trigger the testunit to read bytes
89 access the bus at the same time, the bus will be busy. Example to read 128
90 bytes from device 0x50 after 50ms of delay::
92   # i2cset -y 0 0x30 1 0x50 0x80 5 i
97 .. list-table::
98   :header-rows: 1
100   * - CMD
101     - DATAL
102     - DATAH
103     - DELAY
105   * - 0x02
106     - low byte of the status word to send
107     - high byte of the status word to send
108     - n * 10ms
114   # i2cset -y 0 0x30 2 0x42 0x64 1 i
124 .. list-table::
125   :header-rows: 1
127   * - CMD
128     - DATAL
129     - DATAH
130     - DELAY
132   * - 0x03
133     - 0x01 (i.e. one further byte will be written)
134     - number of bytes to be sent back
135     - leave out, partial command!
139 will be sent back in the following read transfer. Note that in this read
144 from length-1 to 0. Here is an example which emulates
145 i2c_smbus_block_process_call() using i2ctransfer (you need i2c-tools v4.2 or
148   # i2ctransfer -y 0 w3@0x30 3 1 0x10 r?
154 .. list-table::
155   :header-rows: 1
157   * - CMD
158     - DATAL
159     - DATAH
160     - DELAY
162   * - 0x04
163     - currently unused
164     - currently unused
165     - leave out, partial command!
167 Partial command. After sending this command, the testunit will reply to a read
170 128 bytes. However, it will only respond if the read message is connected to
174   # i2ctransfer -y 0 w3@0x30 4 0 0 r128
177 If you have i2c-tools 4.4 or later, you can print out the data right away::
179   # i2ctransfer -y -b 0 w3@0x30 4 0 0 r128
180   v6.11.0-rc1-00009-gd37a1b4d3fd0
186   # i2cset -y 0 0x30 4 0 0 i; i2cget -y 0 0x30
192 .. list-table::
193   :header-rows: 1
195   * - CMD
196     - DATAL
197     - DATAH
198     - DELAY
200   * - 0x05
201     - response value (7 MSBs interpreted as I2C address)
202     - currently unused
203     - n * 10ms
214 second of delay::
216   # i2cset -y 0 0x30 5 0xc9 0x00 100 i
221   smbus_alert 0-000c: SMBALERT# from dev 0x64, flag 1
228    93:          1  gpio-rcar  26 Edge      smbus_alert