i2c_smbus_read_block_data — SMBus block read request
Handle to slave device
Command byte issued to let the slave know what data should be returned
Byte array into which data will be read; big enough to hold the data returned by the slave. SMBus allows at most 32 bytes.
Returns the number of bytes read in the slave's response, else a negative number to indicate some kind of error.
Note that using this function requires that the client's adapter support the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers support this; its emulation through I2C messaging relies on a specific mechanism (I2C_M_RECV_LEN) which may not be implemented.