* @max_message_size: function that returns the max message size for
* a &spi_device; may be %NULL, so the default %SIZE_MAX will be used.
* @io_mutex: mutex for physical bus access
+ * @add_lock: mutex to avoid adding devices to the same chipselect
* @bus_lock_spinlock: spinlock for SPI bus locking
* @bus_lock_mutex: mutex for exclusion of multiple callers
* @bus_lock_flag: indicates that the SPI bus is locked for exclusive use
* @transfer: adds a message to the controller's transfer queue.
* @cleanup: frees controller-specific state
* @can_dma: determine whether this controller supports DMA
+ * @dma_map_dev: device which can be used for DMA mapping
* @queued: whether this controller is providing an internal message queue
* @kworker: pointer to thread struct for message pump
* @pump_messages: work struct for scheduling work to the message pump