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i2c: testunit: improve documentation

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Mention that new CMDs will be NACKed while the old one is still
on-going, that the I2C address parameter of READ_BYTES is 7 bit only,
and reword one paragraph to be more precise.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
This commit is contained in:
Wolfram Sang 2020-09-28 13:06:47 +02:00 committed by Wolfram Sang
parent 06856269d4
commit 35baff672f
1 changed files with 8 additions and 5 deletions
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13
Documentation/i2c/slave-testunit-backend.rst
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@ -20,10 +20,10 @@ Instantiating the device is regular. Example for bus 0, address 0x30:
# echo "slave-testunit 0x1030" > /sys/bus/i2c/devices/i2c-0/new_device
After that, you will have a write-only device listening. Reads will return an
8-bit version number. The device consists of 4 8-bit registers and all must be
written to start a testcase, i.e. you must always write 4 bytes to the device.
The registers are:
After that, you will have a write-only device listening. Reads will just return
an 8-bit version number of the testunit. When writing, the device consists of 4
8-bit registers and all must be written to start a testcase, i.e. you must
always write 4 bytes to the device. The registers are:
0x00 CMD - which test to trigger
0x01 DATAL - configuration byte 1 for the test
@ -35,6 +35,9 @@ Using 'i2cset' from the i2c-tools package, the generic command looks like:
# i2cset -y <bus_num> <testunit_address> <CMD> <DATAL> <DATAH> <DELAY> i
DELAY is a generic parameter which will delay the execution of the test in CMD.
While a command is running (including the delay), new commands will not be
acknowledged. You need to wait until the old one is completed.
The commands are described in the following section. An invalid command will
result in the transfer not being acknowledged.
@ -44,7 +47,7 @@ Commands
0x00 NOOP (reserved for future use)
0x01 READ_BYTES (also needs master mode)
DATAL - address to read data from
DATAL - address to read data from (lower 7 bits, highest bit currently unused)
DATAH - number of bytes to read
This is useful to test if your bus master driver is handling multi-master