spi_controller_spicontroller-优快云博客

/**
 * struct spi_controller - interface to SPI master or slave controller
 * @dev: device interface to this driver
 * @list: link with the global spi_controller list
 * @bus_num: board-specific (and often SOC-specific) identifier for a
 *	given SPI controller.
 * @num_chipselect: chipselects are used to distinguish individual
 *	SPI slaves, and are numbered from zero to num_chipselects.
 *	each slave has a chipselect signal, but it's common that not
 *	every chipselect is connected to a slave.
 * @dma_alignment: SPI controller constraint on DMA buffers alignment.
 * @mode_bits: flags understood by this controller driver
 * @bits_per_word_mask: A mask indicating which values of bits_per_word are
 *	supported by the driver. Bit n indicates that a bits_per_word n+1 is
 *	supported. If set, the SPI core will reject any transfer with an
 *	unsupported bits_per_word. If not set, this value is simply ignored,
 *	and it's up to the individual driver to perform any validation.
 * @min_speed_hz: Lowest supported transfer speed
 * @max_speed_hz: Highest supported transfer speed
 * @flags: other constraints relevant to this driver
 * @slave: indicates that this is an SPI slave controller
 * @max_transfer_size: function that returns the max transfer size for
 *	a &spi_device; may be %NULL, so the default %SIZE_MAX will be used.
 * @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
 * @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
 * @setup: updates the device mode and clocking records used by a
 *	device's SPI controller; protocol code may call this.  This
 *	must fail if an unrecognized or unsupported mode is requested.
 *	It's always safe to call this unless transfers are pending on
 *	the device whose settings are being modified.
 * @transfer: adds a message to the controller's transfer queue.
 * @cleanup: frees controller-specific state
 * @can_dma: determine whether this controller supports DMA
 * @queued: whether this controller is providing an internal message queue
 * @kworker: thread struct for message pump
 * @kworker_task: pointer to task for message pump kworker thread
 * @pump_messages: work struct for scheduling work to the message pump
 * @queue_lock: spinlock to syncronise access to message queue
 * @queue: message queue
 * @idling: the device is entering idle state
 * @cur_msg: the currently in-flight message
 * @cur_msg_prepared: spi_prepare_message was called for the currently
 *                    in-flight message
 * @cur_msg_mapped: message has been mapped for DMA
 * @xfer_completion: used by core transfer_one_message()
 * @busy: message pump is busy
 * @running: message pump is running
 * @rt: whether this queue is set to run as a realtime task
 * @auto_runtime_pm: the core should ensure a runtime PM reference is held
 *                   while the hardware is prepared, using the parent
 *                   device for the spidev
 * @max_dma_len: Maximum length of a DMA transfer for the device.
 * @prepare_transfer_hardware: a message will soon arrive from the queue
 *	so the subsystem requests the driver to prepare the transfer hardware
 *	by issuing this call
 * @transfer_one_message: the subsystem calls the driver to transfer a single
 *	message while queuing transfers that arrive in the meantime. When the
 *	driver is finished with this message, it must call
 *	spi_finalize_current_message() so the subsystem can issue the next
 *	message
 * @unprepare_transfer_hardware: there are currently no more messages on the
 *	queue so the subsystem notifies the driver that it may relax the
 *	hardware by issuing this call
 * @set_cs: set the logic level of the chip select line.  May be called
 *          from interrupt context.
 * @prepare_message: set up the controller to transfer a single message,
 *                   for example doing DMA mapping.  Called from threaded
 *                   context.
 * @transfer_one: transfer a single spi_transfer.
 *                  - return 0 if the transfer is finished,
 *                  - return 1 if the transfer is still in progress. When
 *                    the driver is finished with this transfer it must
 *                    call spi_final