This document is hardly readable when converted to HTML. Mark code sections as such and use tables to improve readability a lot. Some content has slightly been moved around, but no significant changes were made. Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx> --- This is a preparational patch before adding more features to the testunit. Documentation/i2c/slave-testunit-backend.rst | 122 +++++++++++++------ 1 file changed, 82 insertions(+), 40 deletions(-) diff --git a/Documentation/i2c/slave-testunit-backend.rst b/Documentation/i2c/slave-testunit-backend.rst index ecfc2abec32d..0df60c7c0be4 100644 --- a/Documentation/i2c/slave-testunit-backend.rst +++ b/Documentation/i2c/slave-testunit-backend.rst @@ -16,9 +16,9 @@ Note that this is a device for testing and debugging. It should not be enabled in a production build. And while there is some versioning and we try hard to keep backward compatibility, there is no stable ABI guaranteed! -Instantiating the device is regular. Example for bus 0, address 0x30: +Instantiating the device is regular. Example for bus 0, address 0x30:: -# echo "slave-testunit 0x1030" > /sys/bus/i2c/devices/i2c-0/new_device + # echo "slave-testunit 0x1030" > /sys/bus/i2c/devices/i2c-0/new_device 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 @@ -26,14 +26,17 @@ an 8-bit version number of the testunit. When writing, the device consists of 4 written to start a testcase, i.e. you usually write 4 bytes to the device. The registers are: -0x00 CMD - which test to trigger -0x01 DATAL - configuration byte 1 for the test -0x02 DATAH - configuration byte 2 for the test -0x03 DELAY - delay in n * 10ms until test is started +.. csv-table:: + :header: "Offset", "Name", "Description" -Using 'i2cset' from the i2c-tools package, the generic command looks like: + 0x00, CMD, which test to trigger + 0x01, DATAL, configuration byte 1 for the test + 0x02, DATAH, configuration byte 2 for the test + 0x03, DELAY, delay in n * 10ms until test is started -# i2cset -y <bus_num> <testunit_address> <CMD> <DATAL> <DATAH> <DELAY> i +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 @@ -45,44 +48,83 @@ result in the transfer not being acknowledged. Commands -------- -0x00 NOOP (reserved for future use) +0x00 NOOP +~~~~~~~~~ + +Reserved for future use. + +0x01 READ_BYTES +~~~~~~~~~~~~~~~ + +.. list-table:: + :header-rows: 1 + + * - CMD + - DATAL + - DATAH + - DELAY + + * - 0x01 + - address to read data from (lower 7 bits, highest bit currently unused) + - number of bytes to read + - n * 10ms + +Also needs master mode. This is useful to test if your bus master driver is +handling multi-master correctly. You can trigger the testunit to read bytes +from another device on the bus. If the bus master under test also wants to +access the bus at the same time, the bus will be busy. Example to read 128 +bytes from device 0x50 after 50ms of delay:: + + # i2cset -y 0 0x30 0x01 0x50 0x80 0x05 i + +0x02 SMBUS_HOST_NOTIFY +~~~~~~~~~~~~~~~~~~~~~~ + +.. list-table:: + :header-rows: 1 + + * - CMD + - DATAL + - DATAH + - DELAY -0x01 READ_BYTES (also needs master mode) - DATAL - address to read data from (lower 7 bits, highest bit currently unused) - DATAH - number of bytes to read + * - 0x02 + - low byte of the status word to send + - high byte of the status word to send + - n * 10ms -This is useful to test if your bus master driver is handling multi-master -correctly. You can trigger the testunit to read bytes from another device on -the bus. If the bus master under test also wants to access the bus at the same -time, the bus will be busy. Example to read 128 bytes from device 0x50 after -50ms of delay: +Also needs master mode. This test will send an SMBUS_HOST_NOTIFY message to the +host. Note that the status word is currently ignored in the Linux Kernel. +Example to send a notification after 10ms:: -# i2cset -y 0 0x30 0x01 0x50 0x80 0x05 i + # i2cset -y 0 0x30 0x02 0x42 0x64 0x01 i -0x02 SMBUS_HOST_NOTIFY (also needs master mode) - DATAL - low byte of the status word to send - DATAH - high byte of the status word to send +0x03 SMBUS_BLOCK_PROC_CALL +~~~~~~~~~~~~~~~~~~~~~~~~~~ -This test will send an SMBUS_HOST_NOTIFY message to the host. Note that the -status word is currently ignored in the Linux Kernel. Example to send a -notification after 10ms: +.. list-table:: + :header-rows: 1 -# i2cset -y 0 0x30 0x02 0x42 0x64 0x01 i + * - CMD + - DATAL + - DATAH + - DELAY -0x03 SMBUS_BLOCK_PROC_CALL (partial command) - DATAL - must be '1', i.e. one further byte will be written - DATAH - number of bytes to be sent back - DELAY - not applicable, partial command! + * - 0x03 + - must be '1', i.e. one further byte will be written + - number of bytes to be sent back + - leave out, partial command! -This test will respond to a block process call as defined by the SMBus -specification. The one data byte written specifies how many bytes will be sent -back in the following read transfer. Note that in this read transfer, the -testunit will prefix the length of the bytes to follow. So, if your host bus -driver emulates SMBus calls like the majority does, it needs to support the -I2C_M_RECV_LEN flag of an i2c_msg. This is a good testcase for it. The returned -data consists of the length first, and then of an array of bytes from length-1 -to 0. Here is an example which emulates i2c_smbus_block_process_call() using -i2ctransfer (you need i2c-tools v4.2 or later): +Partial command. This test will respond to a block process call as defined by +the SMBus specification. The one data byte written specifies how many bytes +will be sent back in the following read transfer. Note that in this read +transfer, the testunit will prefix the length of the bytes to follow. So, if +your host bus driver emulates SMBus calls like the majority does, it needs to +support the I2C_M_RECV_LEN flag of an i2c_msg. This is a good testcase for it. +The returned data consists of the length first, and then of an array of bytes +from length-1 to 0. Here is an example which emulates +i2c_smbus_block_process_call() using i2ctransfer (you need i2c-tools v4.2 or +later):: -# i2ctransfer -y 0 w3@0x30 0x03 0x01 0x10 r? -0x10 0x0f 0x0e 0x0d 0x0c 0x0b 0x0a 0x09 0x08 0x07 0x06 0x05 0x04 0x03 0x02 0x01 0x00 + # i2ctransfer -y 0 w3@0x30 0x03 0x01 0x10 r? + 0x10 0x0f 0x0e 0x0d 0x0c 0x0b 0x0a 0x09 0x08 0x07 0x06 0x05 0x04 0x03 0x02 0x01 0x00 -- 2.43.0
