SR(4)

NAME
sr - synchronous RISCom/N2 device driver.

SYNOPSYS
device sr0 at isa? port 0x300 net irq 10 iomem 0xd0000 vector arintr device sr1 at isa? port 0x310 net irq 11 flags 0x1 iomem 0xd0000 vector arintr

pseudo-device sppp

DESCRIPTION
The sr driver supports the RISCom/N2 ISA cards that is based on the HD64570 chip.

Line speeds of up to 2Mbps is possible. At this speed about 95% of the bandwidth is usable with 486DX processors.

The standard FreeBSD sppp code is used for the link level layer. The default protocol used is PPP. The Cisco HDLC protocol can be used by adding link2 to ifconfig(8).

The flags field is optional. If it isn't specified, the driver will assume the following:

The card has 2 ports.

The clock for the serial ports is external and the transmitter uses
    the same clock as the receiver.

The flags are a bit field and can be used to force a different behaviour than the default.

0x01
    The card has only one port.

0x10
    Use sepperate external clocks for transmit and receive on port 0.

0x40
    Use sepperate external clocks for transmit and receive on port 1.

NUMBERING
Only one line for each card is needed in the kernel configuration file. The first card's ports will be installed from sr0. The numbering of the next card will continue where the first stopped, eg. if the first card is a two port card it will use sr0 and sr1. The next card will then start at sr2.

The card only supports IRQ 3, 4, 5, 7, 10, 11, 12 and 15.

The iomem area is a 16Kb block and must start at a 16Kb boundary.

DIAGNOSTICS

sr%d: Warning illegal interrupt %d. The card cannot use the specified interrupt. Choose a different one.

FILES
/sys/i386/isa/ic/hd64570.h
/sys/i386/isa/if_srregs.h
/sys/i386/isa/if_sr.c

BUGS
At the moment only the X.21 interface is tested. The others may need tweaks to the clock selection code.

The code can probably stand some optimizing.

There must be lots because this code is still very green. Please report them to jhay@mikom.csir.co.za

SEE ALSO
ar(4), cx(4), netintro(4), ifconfig(8), lsdev(8)

AUTHOR
The sr device driver was written by John Hay, jhay@mikom.csir.co.za.