i2c_smbus_read_block_data(9) suse man page | unix.com

I2C_SMBUS_READ_BLOCK(9) 				      I2C and SMBus Subsystem					   I2C_SMBUS_READ_BLOCK(9)

NAME
       i2c_smbus_read_block_data - SMBus "block read" protocol

SYNOPSIS
       s32 i2c_smbus_read_block_data(struct i2c_client * client, u8 command, u8 * values);

ARGUMENTS
       client
	   Handle to slave device

       command
	   Byte interpreted by slave

       values
	   Byte array into which data will be read; big enough to hold the data returned by the slave. SMBus allows at most 32 bytes.

DESCRIPTION
       This executes the SMBus "block read" protocol, returning negative errno else the number of data bytes in the slave's response.

       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.

COPYRIGHT
Kernel Hackers Manual 2.6.					     July 2010						   I2C_SMBUS_READ_BLOCK(9)