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NetBSD 6.1.5 - man page for ntwoc (netbsd section 4)

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NTWOC(4)			   BSD Kernel Interfaces Manual 			 NTWOC(4)

NAME
     ntwoc -- Riscom/N2, N2pci, WANic 400 synchronous serial interfaces

SYNOPSIS
     ntwoc* at pci? dev ? function ? flags 0
     ntwoc0 at isa? port 0x300 irq 5 iomem 0xc8000 flags 1

DESCRIPTION
     The ntwoc device driver supports bit-synchronous serial communication using Cisco HDLC fram-
     ing.  The cards are capable of being driven by the line clock or from an internal baud rate
     generator.  The devices all use the Hitachi hd64570 serial chip.  The hd64570 supports 2
     asynchronous/byte-synchronous/bit-synchronous serial ports, and has a 4-channel DMA con-
     troller for loading the serial port FIFOs.

     The ISA Riscom/N2 card has a jumper block to set the IRQ and a DIP switch to set the port
     address the card will use.  The values programmed into the card must be specified with the
     port and irq locators in the kernel configuration line.  The iomem locator must be specified
     and must occur on a 16k boundary.	The driver uses a 16k region of io memory.  Bit 0 of the
     flags locator indicates if there is a second serial port available on the card.

     Currently clock source and speed information is specified with the flags locator in the ker-
     nel configuration file.  The flags field has the following format.

       3		   2		       1
     1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
     +-------------+ +-----+ +-----+ + +---+ +-+     + +---+ +-+   +
	   tmc	       tdiv    rdiv  e1 rxs1 ts1    e0 rxs0  txs0  np(*)

     tmc	Defines the timer constant.  The base clock frequency is divided by tmc to gener-
		ate the main clock for receiving and sending.  Further division is possible with
		the tdiv and rdiv divisor options.  A value of 0 is treated as 256.

     tdiv	Defines the transmit divisor as 2^(tdiv).  The internal transmit clock frequency
		is determined by dividing the base clock frequency by tmc and then dividing by
		2^(tdiv).

     rdiv	Defines the receive divisor as 2^(rdiv).  The internal receive clock frequency is
		determined by dividing the base clock frequency by tmc and then dividing by
		2^(rdiv).

     e0 e1	If true the internal clock source is used to drive the line clock for port 0 or
		port 1 respectively.

     rxs0 rxs1	Specifies which clock source to use for receiving data on port 0 and port 1
		respectively.  The following values are accepted:

		0
		  Line clock.
		1
		  Line clock with noise suppression.
		2
		  Internal clock.

     txs0 txs1	Specifies which clock source to use for transmitting data on port 0 and port 1
		respectively.  The following values are accepted:

		0
		  Line clock.
		1
		  Internal clock.
		2
		  Receive clock.

     np 	(For the ISA card only) A value of 1 indicates there is a second serial port
		present on the card.  This is auto-detected on the PCI card and need not be spec-
		ified.

HARDWARE
     Cards supported by the ntwoc driver include:

     SDL Communications Riscom/N2
     SDL Communications N2pci
     SDL Communications WANic 400 (untested)

DIAGNOSTICS
     ntwoc0: TXDMA underrun - fifo depth maxed	Indicates that the serial port's FIFO is being
     drained faster than DMA can fill it.  The driver automatically increases the low-water mark
     at which to begin DMA transfers when underruns occur.  This diagnostic is issued when the
     low-water mark is maximized (i.e., 1 less than the depth of the FIFO).

     ntwoc0: RXDMA buffer overflow  Indicates that a frame is being received by the card, but
     there are no free receive buffers.

SEE ALSO
     intro(4), isa(4), pci(4), ifconfig(8)

HISTORY
     The PCI driver first appeared in NetBSD 1.4.  Much of the ISA driver was adapted from the
     FreeBSD sr driver and first appeared in NetBSD 1.5.

BUGS
     Use of the flags locator for setting the clock sources and speeds should be replaced with
     ioctl's and a control program.

BSD					 October 2, 1998				      BSD
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