#
# For a description of the syntax of this configuration file,
# see the file kconfig-language.txt in the NuttX tools repository.
#

if CAN

config CAN_EXTID
	bool "CAN extended IDs"
	default n
	---help---
		Enables support for the 29-bit extended ID.  Default Standard 11-bit
		IDs.

config ARCH_HAVE_CAN_ERRORS
	bool
	default n

config CAN_ERRORS
	bool "CAN error reporting"
	default n
	depends on ARCH_HAVE_CAN_ERRORS
	---help---
		Support CAN error reporting.  If this option is selected then CAN
		error reporting is enabled.  In the event of an error, the ch_error
		bit will be set in the CAN message and the following message payload
		will include a more detailed description of certain errors.

config CAN_FD
	bool "CAN FD"
	default n
	---help---
		Enables support for the CAN_FD mode.

config CAN_FIFOSIZE
	int "CAN driver I/O buffer size"
	default 8
	---help---
		The size of the circular buffer of CAN messages. Default: 8

config CAN_NPENDINGRTR
	int "Number of pending RTRs"
	default 4
	---help---
		The size of the list of pending RTR requests. Default: 4

config CAN_TXREADY
	bool "can_txready interface"
	default n
	select SCHED_WORKQUEUE
	---help---
		This selection enables the can_txready() interface.  This interface
		is needed only for CAN hardware that supports queing of outgoing
		messages in a H/W FIFO.

		The CAN upper half driver also supports a queue of output messages
		in a S/W FIFO.  Messages are added to that queue when when
		can_write() is called and removed from the queue in can_txdone()
		when each TX message is complete.

		After each message is added to the S/W FIFO, the CAN upper half
		driver will attempt to send the message by calling into the lower
		half driver.  That send will not be performed if the lower half
		driver is busy, i.e., if dev_txready() returns false.  In that
		case, the number of messages in the S/W FIFO can grow.  If the
		S/W FIFO becomes full, then can_write() will wait for space in
		the S/W FIFO.

		If the CAN hardware does not support a H/W FIFO then busy means
		that the hardware is actively sending the message and is
		guaranteed to become non busy (i.e, dev_txready()) when the
		send transfer completes and can_txdone() is called.  So the call
		to can_txdone() means that the transfer has completed and also
		that the hardware is ready to accept another transfer.

		If the CAN hardware supports a H/W FIFO, can_txdone() is not
		called when the tranfer is complete, but rather when the
		transfer is queued in the H/W FIFO.  When the H/W FIFO becomes
		full, then dev_txready() will report false and the number of
		queued messages in the S/W FIFO will grow.

		There is no mechanism in this case to inform the upper half
		driver when the hardware is again available, when there is
		again space in the H/W FIFO.  can_txdone() will not be called
		again.  If the S/W FIFO becomes full, then the upper half
		driver will wait for space to become available, but there is
		no event to awaken it and the driver will hang.

		Enabling this feature adds support for the can_txready()
		interface.  This function is called from the lower half
		driver's CAN interrupt handler each time a TX transfer
		completes.  This is a sure indication that the H/W FIFO is
		no longer full.  can_txready() will then awaken the
		can_write() logic and the hang condition is avoided.

choice
	prompt "TX Ready Work Queue"
	default CAN_TXREADY_HIPRI
	depends on CAN_TXREADY

config CAN_TXREADY_LOPRI
	bool "Low-priority work queue"
	select SCHED_LPWORK

config CAN_TXREADY_HIPRI
	bool "High-priority work queue"
	select SCHED_HPWORK

endchoice # TX Ready Work Queue

config CAN_LOOPBACK
	bool "CAN loopback mode"
	default n
	---help---
		A CAN driver may or may not support a loopback mode for testing. If the
		driver does support loopback mode, the setting will enable it. (If the
		driver does not, this setting will have no effect).

config CAN_NPOLLWAITERS
	int "Number of poll waiters"
	default 2
	depends on !DISABLE_POLL
	---help---
		The maximum number of threads that may be waiting on the
		poll method.

endif # CAN