The following serial patches were generated versus Linux 1.1.90.  

They should hopefully improve support for certain Multiport serial
boards, including the AST Fourport and the Boca BB-1004, BB-1008, and
BB-2016 boards.  

In order to apply these patches, cd to /usr/src/linux (or wherever the
top level of your kernel sources are, and run "patch -p0 < patches.serial".
Then, recompile the kernel.

You will also need setserial version 2.12 or higher, which can be
found in this directory.  Compile it, and the modify your rc.serial
file to configure the multiport information.  

Configuration of the multiport information
==========================================

The basic idea of how the multiport support works is that up to four
ports will be sampled by the interrupt service routine.  When the
value of all active ports is masked against a mask and compares
equally to the match value, then the interrupt service routine will
exit.  Otherwise, it will continue polling the serial ports on the
multiport serial board.  

There is a safety mechanism which prevents incorrect match values from
hanging the system; however, incorrect values will significantly
decrease system performance.  If you have entered incorrect values,
you will see kernel printks (either on your console or in your kernel
syslog file) stating "rs_multi loop break".  

Here are some sample multiport configuration values for common boards:

----------------------------------------------------------------------

AST FourPort:

The AST Fourport uses a status register located at the scratch
register of the fourth port; the low order four bits represent the
interrupt status of the four ports, with a '0' bit meaning that the
port needs to be serviced, and a '1' bit meaning that the port does
not need any servicing.

At I/O port address 0x1A0:
setserial /dev/cua4 set_multiport port1 0x1BF match1 0xf mask1 0xf

At I/O port address 0x2A0:
setserial /dev/cua4 set_multiport port1 0x2BF match1 0xf mask1 0xf

----------------------------------------------------------------------

Boca BB-1004, BB-1008, BB-2016 (at port address 0x100):

The Bocaboards use a status register which can be found at the scratch
register location of every port.  A '1' bit means that the port needs
to be serviced, and a '0' bit means that no service is necessary for
that port.  The first port uses the least significant bit (2^0), the
second port uses the 2^1 bit, and so on.

For the BB-2016, there are two status registered; the first one is
located at the scratch registers for the first 8 ports, and the second
one is located at the scratch register of the last 8 ports. 

BB-1004: (at port address 0x100)
setserial /dev/cua16 set_multiport port1 0x107 match1 0xf match1 0

BB-1008: (at port address 0x100)
setserial /dev/cua16 set_multiport port1 0x107 match1 0xff match1 0

Boca BB-2016: (at port address 0x100)

setserial /dev/cua16 set_multiport port1 0x107 match1 0xff match1 0 \
	port2 0x147 match2 0xff match2 0

----------------------------------------------------------------------

Note: be sure to configure the IRQ and port information for all of the
ports first, before configuring the multiport information.  This is
important!  The multiport information is associated with an IRQ, not
with a specific port; hence, if the IRQ information for the port is
not set first, the multiport configuration may be registered against
the wrong IRQ.