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Diffstat (limited to 'Documentation/i2c')
| -rw-r--r-- | Documentation/i2c/slave-testunit-backend.rst | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/Documentation/i2c/slave-testunit-backend.rst b/Documentation/i2c/slave-testunit-backend.rst index 2c38e64f0bac..ecfc2abec32d 100644 --- a/Documentation/i2c/slave-testunit-backend.rst +++ b/Documentation/i2c/slave-testunit-backend.rst @@ -22,8 +22,9 @@ Instantiating the device is regular. Example for bus 0, address 0x30: 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: +8-bit registers and, except for some "partial" commands, all registers must be +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 @@ -67,3 +68,21 @@ status word is currently ignored in the Linux Kernel. Example to send a notification after 10ms: # i2cset -y 0 0x30 0x02 0x42 0x64 0x01 i + +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! + +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 |