It improves on sio(4) in the following areas:
o Fully newbusified to allow for memory mapped I/O. This is a must
for ia64 and sparc64,
o Machine dependent code to take full advantage of machine and firm-
ware specific ways to define serial consoles and/or debug ports.
o Hardware abstraction layer to allow the driver to be used with
various UARTs, such as the well-known ns8250 family of UARTs, the
Siemens sab82532 or the Zilog Z8530. This is especially important
for pc98 and sparc64 where it's common to have different UARTs,
o The notion of system devices to unkludge low-level consoles and
remote gdb ports and provides the mechanics necessary to support
the keyboard on sparc64 (which is UART based).
o The notion of a kernel interface so that a UART can be tied to
something other than the well-known TTY interface. This is needed
on sparc64 to present the user with a device and ioctl handling
suitable for a keyboard, but also allows us to cleanly hide an
UART when used as a debug port.
Following is a list of features and bugs/flaws specific to the ns8250
family of UARTs as compared to their support in sio(4):
o The uart(4) driver determines the FIFO size and automaticly takes
advantages of larger FIFOs and/or additional features. Note that
since I don't have sufficient access to 16[679]5x UARTs, hardware
flow control has not been enabled. This is almost trivial to do,
provided one can test. The downside of this is that broken UARTs
are more likely to not work correctly with uart(4). The need for
tunables or knobs may be large enough to warrant their creation.
o The uart(4) driver does not share the same bumpy history as sio(4)
and will therefore not provide the necessary hooks, tweaks, quirks
or work-arounds to deal with once common hardware. To that extend,
uart(4) supports a subset of the UARTs that sio(4) supports. The
question before us is whether the subset is sufficient for current
hardware.
o There is no support for multiport UARTs in uart(4). The decision
behind this is that uart(4) deals with one EIA RS232-C interface.
Packaging of multiple interfaces in a single chip or on a single
expansion board is beyond the scope of uart(4) and is now mostly
left for puc(4) to deal with. Lack of hardware made it impossible
to actually implement such a dependency other than is present for
the dual channel SAB82532 and Z8350 SCCs.
The current list of missing features is:
o No configuration capabilities. A set of tunables and sysctls is
being worked out. There are likely not going to be any or much
compile-time knobs. Such configuration does not fit well with
current hardware.
o No support for the PPS API. This is partly dependent on the
ability to configure uart(4) and partly dependent on having
sufficient information to implement it properly.
As usual, the manpage is present but lacks the attention the
software has gotten.
hardware is interrupt-driven to a fault and sending a BREAK requires
mode switching. Always running in the BREAK-capable mode as in PR 8318
would double the overhead for sending \0's.
Reminded by: PR 8318
number of dma overruns/underruns for systems under heavy dma load.
As a side effect, broken enhanced floppy controllers that sometimes
don't detect dma overruns/underruns will give less errors.
Reviewed by: j@uriah.heep.sax.de (J Wunsch)
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
(1) Add PC98 support to apm_bios.h and ns16550.h, remove pc98/pc98/ic
(2) Move PC98 specific code out of cpufunc.h (to pc98.h)
(3) Let the boot subtrees look more alike
Submitted by: The FreeBSD(98) Development Team
<freebsd98-hackers@jp.freebsd.org>
1. Create 2 x 8k transmit buffer blocks in place of the 16k block previously.
With this change the speed as tested with ttcp on a 2Mbit link went up
from 206kbyte/s to 236kbyte/s.
2. Change the rest of the functions to also have the definition of the
return value on a sepperate line.
3. Remove some unused variables.
4. Add code to recover from DMA underruns.
5. Reorder ar_get_packets() to handle errors better.
6. Only allocate a mbuf cluster if the data is more than the mbuf.
(and in a second diff in addition to the above)
7. Stops the occasional DMA underruns that occurred when 2 channels
are running at 2Mbit/s.
Submitted by: John Hay <jhay@mikom.csir.co.za>
HD64570 chip. Both the 2 and 4 port cards is supported and auto detected.
Line speeds of up to 2Mbps is possible. At this speed about 85% 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 the ifconfig line in /etc/sysconfig or where ever
ifconfig is run.
At the moment only the V.35 and X.21 interfaces is supported. The others
may need tweaks to the clock selection code.
Submitted by: John Hay <jhay@mikom.csir.co.za>
- use pseudo-dma
- provide the same features and interface as sio
- support multiple boards
- fix bugs.
Some compile-time configuration constants are set to support higher
speeds and Cyclom-16Y's at a 30% relative cost in efficiency.
Cyclom-16Y support is untested.
adapted to FreeBSD by Heikki Suonsivu <hsu@cs.hut.fi>.
Submitted by: Andrew Werple <andrew@werple.apana.org.au> and
Heikki Suonsivu <hsu@cs.hut.fi>
Obtained from: NetBSD
floppy driver (or in the hardware?). It turned out to be caused by
spurious interrupts, right after an FDC reset.
Also major cleanup in the low-level structure, there are now functions
performing error-checks for the FDC I/O.
Submitted by: (mostly) Peter Dufault <dufault@FreeBSD.org>
date: 1994/05/22 12:35:38; author: joerg; state: Exp; lines: +6 -6
First round of floppy changes. Try making `fd' more robust.
New features:
. ioctl command for setting the drive type (density etc.); restricted
to the super-user
. ioctl for getting/seting `drive options'; currently only option
is FDOPT_NORETRY: inhibit the usual retries; used when verifying
a newly formatted track
Fixes:
. function prototypes
. made all internal functions `static'
. cleaned up & corrected .h files
. restructured, to make the chaotic function sequence more rational
. compiled with -Wall, and cleared all warnings
. introduced a mirror for the (write-only) `digital output register',
to avoid the current kludge
. device probing completed by seeking/recalibrating, and looking
for track 0 being found
. holding the controller down in reset state while it is idle (and
thus saving allot of headaches)
. make requests fail that are not a multiple of the (physical)
sector size
. removed the fixed physical sector size (512 bytes), allowing for any
size the controller could handle (128/256/512/1024 bytes)
. replaced some silly messages
. fixed the TRACE* macro usage, debugging reports should be complete
now again (debugging output is HUGE! though)
. removed fd_timeout for SEEK command; seeks are always reported by
the controller to succeed, since the `success' only refers to the
controller's idea of success - there is no hardware line to tell about
the seek end (other than the `track 0' line)
. catch SENSEI's that report about a `terminated due to READY changed'
status - could happen after a controller reset
. converted ``hz / <something>'' divide operations to divisors that are
powers of two, so gcc can optimize them into shifts
. write/format operations are checked against a write-protected medium
now *prior* starting the operation
. error reports of `invalid command' and `wrong cylinder' will cause
shortcuts in the retrier() now
. fixed a bug in the retrier() causing bogus block numbers to be reported
. fdformat() does care for errors now
Known Bugs:
. no attempts have been made (yet) to improve the performance
. sometimes, bogus ``seek/recalib failed'' messages are logged; this
is still a bug in the driver, but it's not harmful since it's
usually caught by the retrier()
Reviewed by:
Submitted by:
Obtained from:
