title: read() and write() using spi device driver
body: <p>I would use the read() and write() for the /dev/spiB.C which is created by the user mode spi device driver (spidev.c). Now, the SPI ransaction message follows a certain format (e.g., 24 bits, with some bits for address and some bits for data) which is defined by the chip-vendor-specific spi controller driver. How is the message format fit into the read() and write() transaction? Where and how should I define the format in the code before or after the write() or read()?</p>
  
  <p>Thanks!</p>