mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-15 08:44:14 +08:00
1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
321 lines
12 KiB
Plaintext
321 lines
12 KiB
Plaintext
i386 Micro Channel Architecture Support
|
|
=======================================
|
|
|
|
MCA support is enabled using the CONFIG_MCA define. A machine with a MCA
|
|
bus will have the kernel variable MCA_bus set, assuming the BIOS feature
|
|
bits are set properly (see arch/i386/boot/setup.S for information on
|
|
how this detection is done).
|
|
|
|
Adapter Detection
|
|
=================
|
|
|
|
The ideal MCA adapter detection is done through the use of the
|
|
Programmable Option Select registers. Generic functions for doing
|
|
this have been added in include/linux/mca.h and arch/i386/kernel/mca.c.
|
|
Everything needed to detect adapters and read (and write) configuration
|
|
information is there. A number of MCA-specific drivers already use
|
|
this. The typical probe code looks like the following:
|
|
|
|
#include <linux/mca.h>
|
|
|
|
unsigned char pos2, pos3, pos4, pos5;
|
|
struct net_device* dev;
|
|
int slot;
|
|
|
|
if( MCA_bus ) {
|
|
slot = mca_find_adapter( ADAPTER_ID, 0 );
|
|
if( slot == MCA_NOTFOUND ) {
|
|
return -ENODEV;
|
|
}
|
|
/* optional - see below */
|
|
mca_set_adapter_name( slot, "adapter name & description" );
|
|
mca_set_adapter_procfn( slot, dev_getinfo, dev );
|
|
|
|
/* read the POS registers. Most devices only use 2 and 3 */
|
|
pos2 = mca_read_stored_pos( slot, 2 );
|
|
pos3 = mca_read_stored_pos( slot, 3 );
|
|
pos4 = mca_read_stored_pos( slot, 4 );
|
|
pos5 = mca_read_stored_pos( slot, 5 );
|
|
} else {
|
|
return -ENODEV;
|
|
}
|
|
|
|
/* extract configuration from pos[2345] and set everything up */
|
|
|
|
Loadable modules should modify this to test that the specified IRQ and
|
|
IO ports (plus whatever other stuff) match. See 3c523.c for example
|
|
code (actually, smc-mca.c has a slightly more complex example that can
|
|
handle a list of adapter ids).
|
|
|
|
Keep in mind that devices should never directly access the POS registers
|
|
(via inb(), outb(), etc). While it's generally safe, there is a small
|
|
potential for blowing up hardware when it's done at the wrong time.
|
|
Furthermore, accessing a POS register disables a device temporarily.
|
|
This is usually okay during startup, but do _you_ want to rely on it?
|
|
During initial configuration, mca_init() reads all the POS registers
|
|
into memory. mca_read_stored_pos() accesses that data. mca_read_pos()
|
|
and mca_write_pos() are also available for (safer) direct POS access,
|
|
but their use is _highly_ discouraged. mca_write_pos() is particularly
|
|
dangerous, as it is possible for adapters to be put in inconsistent
|
|
states (i.e. sharing IO address, etc) and may result in crashes, toasted
|
|
hardware, and blindness.
|
|
|
|
User level drivers (such as the AGX X server) can use /proc/mca/pos to
|
|
find adapters (see below).
|
|
|
|
Some MCA adapters can also be detected via the usual ISA-style device
|
|
probing (many SCSI adapters, for example). This sort of thing is highly
|
|
discouraged. Perfectly good information is available telling you what's
|
|
there, so there's no excuse for messing with random IO ports. However,
|
|
we MCA people still appreciate any ISA-style driver that will work with
|
|
our hardware. You take what you can get...
|
|
|
|
Level-Triggered Interrupts
|
|
==========================
|
|
|
|
Because MCA uses level-triggered interrupts, a few problems arise with
|
|
what might best be described as the ISA mindset and its effects on
|
|
drivers. These sorts of problems are expected to become less common as
|
|
more people use shared IRQs on PCI machines.
|
|
|
|
In general, an interrupt must be acknowledged not only at the ICU (which
|
|
is done automagically by the kernel), but at the device level. In
|
|
particular, IRQ 0 must be reset after a timer interrupt (now done in
|
|
arch/i386/kernel/time.c) or the first timer interrupt hangs the system.
|
|
There were also problems with the 1.3.x floppy drivers, but that seems
|
|
to have been fixed.
|
|
|
|
IRQs are also shareable, and most MCA-specific devices should be coded
|
|
with shared IRQs in mind.
|
|
|
|
/proc/mca
|
|
=========
|
|
|
|
/proc/mca is a directory containing various files for adapters and
|
|
other stuff.
|
|
|
|
/proc/mca/pos Straight listing of POS registers
|
|
/proc/mca/slot[1-8] Information on adapter in specific slot
|
|
/proc/mca/video Same for integrated video
|
|
/proc/mca/scsi Same for integrated SCSI
|
|
/proc/mca/machine Machine information
|
|
|
|
See Appendix A for a sample.
|
|
|
|
Device drivers can easily add their own information function for
|
|
specific slots (including integrated ones) via the
|
|
mca_set_adapter_procfn() call. Drivers that support this are ESDI, IBM
|
|
SCSI, and 3c523. If a device is also a module, make sure that the proc
|
|
function is removed in the module cleanup. This will require storing
|
|
the slot information in a private structure somewhere. See the 3c523
|
|
driver for details.
|
|
|
|
Your typical proc function will look something like this:
|
|
|
|
static int
|
|
dev_getinfo( char* buf, int slot, void* d ) {
|
|
struct net_device* dev = (struct net_device*) d;
|
|
int len = 0;
|
|
|
|
len += sprintf( buf+len, "Device: %s\n", dev->name );
|
|
len += sprintf( buf+len, "IRQ: %d\n", dev->irq );
|
|
len += sprintf( buf+len, "IO Port: %#lx-%#lx\n", ... );
|
|
...
|
|
|
|
return len;
|
|
}
|
|
|
|
Some of the standard MCA information will already be printed, so don't
|
|
bother repeating it. Don't try putting in more than 3K of information.
|
|
|
|
Enable this function with:
|
|
mca_set_adapter_procfn( slot, dev_getinfo, dev );
|
|
|
|
Disable it with:
|
|
mca_set_adapter_procfn( slot, NULL, NULL );
|
|
|
|
It is also recommended that, even if you don't write a proc function, to
|
|
set the name of the adapter (i.e. "PS/2 ESDI Controller") via
|
|
mca_set_adapter_name( int slot, char* name ).
|
|
|
|
MCA Device Drivers
|
|
==================
|
|
|
|
Currently, there are a number of MCA-specific device drivers.
|
|
|
|
1) PS/2 ESDI
|
|
drivers/block/ps2esdi.c
|
|
include/linux/ps2esdi.h
|
|
Uses major number 36, and should use /dev files /dev/eda, /dev/edb.
|
|
Supports two drives, but only one controller. May use the
|
|
command-line args "ed=cyl,head,sec" and "tp720".
|
|
|
|
2) PS/2 SCSI
|
|
drivers/scsi/ibmmca.c
|
|
drivers/scsi/ibmmca.h
|
|
The driver for the IBM SCSI subsystem. Includes both integrated
|
|
controllers and adapter cards. May require command-line arg
|
|
"ibmmcascsi=io_port" to force detection of an adapter. If you have a
|
|
machine with a front-panel display (i.e. model 95), you can use
|
|
"ibmmcascsi=display" to enable a drive activity indicator.
|
|
|
|
3) 3c523
|
|
drivers/net/3c523.c
|
|
drivers/net/3c523.h
|
|
3Com 3c523 Etherlink/MC ethernet driver.
|
|
|
|
4) SMC Ultra/MCA and IBM Adapter/A
|
|
drivers/net/smc-mca.c
|
|
drivers/net/smc-mca.h
|
|
Driver for the MCA version of the SMC Ultra and various other
|
|
OEM'ed and work-alike cards (Elite, Adapter/A, etc).
|
|
|
|
5) NE/2
|
|
driver/net/ne2.c
|
|
driver/net/ne2.h
|
|
The NE/2 is the MCA version of the NE2000. This may not work
|
|
with clones that have a different adapter id than the original
|
|
NE/2.
|
|
|
|
6) Future Domain MCS-600/700, OEM'd IBM Fast SCSI Aapter/A and
|
|
Reply Sound Blaster/SCSI (SCSI part)
|
|
Better support for these cards than the driver for ISA.
|
|
Supports multiple cards with IRQ sharing.
|
|
|
|
Also added boot time option of scsi-probe, which can do reordering of
|
|
SCSI host adapters. This will direct the kernel on the order which
|
|
SCSI adapter should be detected. Example:
|
|
scsi-probe=ibmmca,fd_mcs,adaptec1542,buslogic
|
|
|
|
The serial drivers were modified to support the extended IO port range
|
|
of the typical MCA system (also #ifdef CONFIG_MCA).
|
|
|
|
The following devices work with existing drivers:
|
|
1) Token-ring
|
|
2) Future Domain SCSI (MCS-600, MCS-700, not MCS-350, OEM'ed IBM SCSI)
|
|
3) Adaptec 1640 SCSI (using the aha1542 driver)
|
|
4) Bustek/Buslogic SCSI (various)
|
|
5) Probably all Arcnet cards.
|
|
6) Some, possibly all, MCA IDE controllers.
|
|
7) 3Com 3c529 (MCA version of 3c509) (patched)
|
|
|
|
8) Intel EtherExpressMC (patched version)
|
|
You need to have CONFIG_MCA defined to have EtherExpressMC support.
|
|
9) Reply Sound Blaster/SCSI (SB part) (patched version)
|
|
|
|
Bugs & Other Weirdness
|
|
======================
|
|
|
|
NMIs tend to occur with MCA machines because of various hardware
|
|
weirdness, bus timeouts, and many other non-critical things. Some basic
|
|
code to handle them (inspired by the NetBSD MCA code) has been added to
|
|
detect the guilty device, but it's pretty incomplete. If NMIs are a
|
|
persistent problem (on some model 70 or 80s, they occur every couple
|
|
shell commands), the CONFIG_IGNORE_NMI flag will take care of that.
|
|
|
|
Various Pentium machines have had serious problems with the FPU test in
|
|
bugs.h. Basically, the machine hangs after the HLT test. This occurs,
|
|
as far as we know, on the Pentium-equipped 85s, 95s, and some PC Servers.
|
|
The PCI/MCA PC 750s are fine as far as I can tell. The ``mca-pentium''
|
|
boot-prompt flag will disable the FPU bug check if this is a problem
|
|
with your machine.
|
|
|
|
The model 80 has a raft of problems that are just too weird and unique
|
|
to get into here. Some people have no trouble while others have nothing
|
|
but problems. I'd suspect some problems are related to the age of the
|
|
average 80 and accompanying hardware deterioration, although others
|
|
are definitely design problems with the hardware. Among the problems
|
|
include SCSI controller problems, ESDI controller problems, and serious
|
|
screw-ups in the floppy controller. Oh, and the parallel port is also
|
|
pretty flaky. There were about 5 or 6 different model 80 motherboards
|
|
produced to fix various obscure problems. As far as I know, it's pretty
|
|
much impossible to tell which bugs a particular model 80 has (other than
|
|
triggering them, that is).
|
|
|
|
Drivers are required for some MCA memory adapters. If you're suddenly
|
|
short a few megs of RAM, this might be the reason. The (I think) Enhanced
|
|
Memory Adapter commonly found on the model 70 is one. There's a very
|
|
alpha driver floating around, but it's pretty ugly (disassembled from
|
|
the DOS driver, actually). See the MCA Linux web page (URL below)
|
|
for more current memory info.
|
|
|
|
The Thinkpad 700 and 720 will work, but various components are either
|
|
non-functional, flaky, or we don't know anything about them. The
|
|
graphics controller is supposed to be some WD, but we can't get things
|
|
working properly. The PCMCIA slots don't seem to work. Ditto for APM.
|
|
The serial ports work, but detection seems to be flaky.
|
|
|
|
Credits
|
|
=======
|
|
A whole pile of people have contributed to the MCA code. I'd include
|
|
their names here, but I don't have a list handy. Check the MCA Linux
|
|
home page (URL below) for a perpetually out-of-date list.
|
|
|
|
=====================================================================
|
|
MCA Linux Home Page: http://glycerine.itsmm.uni.edu/mca/
|
|
|
|
Christophe Beauregard
|
|
chrisb@truespectra.com
|
|
cpbeaure@calum.csclub.uwaterloo.ca
|
|
|
|
=====================================================================
|
|
Appendix A: Sample /proc/mca
|
|
|
|
This is from my model 8595. Slot 1 contains the standard IBM SCSI
|
|
adapter, slot 3 is an Adaptec AHA-1640, slot 5 is a XGA-1 video adapter,
|
|
and slot 7 is the 3c523 Etherlink/MC.
|
|
|
|
/proc/mca/machine:
|
|
Model Id: 0xf8
|
|
Submodel Id: 0x14
|
|
BIOS Revision: 0x5
|
|
|
|
/proc/mca/pos:
|
|
Slot 1: ff 8e f1 fc a0 ff ff ff IBM SCSI Adapter w/Cache
|
|
Slot 2: ff ff ff ff ff ff ff ff
|
|
Slot 3: 1f 0f 81 3b bf b6 ff ff
|
|
Slot 4: ff ff ff ff ff ff ff ff
|
|
Slot 5: db 8f 1d 5e fd c0 00 00
|
|
Slot 6: ff ff ff ff ff ff ff ff
|
|
Slot 7: 42 60 ff 08 ff ff ff ff 3Com 3c523 Etherlink/MC
|
|
Slot 8: ff ff ff ff ff ff ff ff
|
|
Video : ff ff ff ff ff ff ff ff
|
|
SCSI : ff ff ff ff ff ff ff ff
|
|
|
|
/proc/mca/slot1:
|
|
Slot: 1
|
|
Adapter Name: IBM SCSI Adapter w/Cache
|
|
Id: 8eff
|
|
Enabled: Yes
|
|
POS: ff 8e f1 fc a0 ff ff ff
|
|
Subsystem PUN: 7
|
|
Detected at boot: Yes
|
|
|
|
/proc/mca/slot3:
|
|
Slot: 3
|
|
Adapter Name: Unknown
|
|
Id: 0f1f
|
|
Enabled: Yes
|
|
POS: 1f 0f 81 3b bf b6 ff ff
|
|
|
|
/proc/mca/slot5:
|
|
Slot: 5
|
|
Adapter Name: Unknown
|
|
Id: 8fdb
|
|
Enabled: Yes
|
|
POS: db 8f 1d 5e fd c0 00 00
|
|
|
|
/proc/mca/slot7:
|
|
Slot: 7
|
|
Adapter Name: 3Com 3c523 Etherlink/MC
|
|
Id: 6042
|
|
Enabled: Yes
|
|
POS: 42 60 ff 08 ff ff ff ff
|
|
Revision: 0xe
|
|
IRQ: 9
|
|
IO Address: 0x3300-0x3308
|
|
Memory: 0xd8000-0xdbfff
|
|
Transceiver: External
|
|
Device: eth0
|
|
Hardware Address: 02 60 8c 45 c4 2a
|