patch-2.2.8 linux/arch/m68k/q40/README

• Lines: 122
• Date: Tue May 11 09:57:14 1999
• Orig file: v2.2.7/linux/arch/m68k/q40/README
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.2.7/linux/arch/m68k/q40/README linux/arch/m68k/q40/README
@@ -0,0 +1,121 @@
+Linux for the Q40
+=================
+
+You may try http://www.geocities.com/SiliconValley/Bay/2602/ for
+some up to date information. Booter and other tools will be also
+available from this place and ftp.uni-erlangen.de/linux/680x0/q40/
+and mirrors.
+
+Hints to documentation usually refer to the linux source tree in
+/usr/src/linux unless URL given.
+
+It seems IRQ unmasking can't be safely done on a Q40. Autoprobing is 
+not yet implemented - do not try it! (See below)
+
+For a list of kernel commandline options read the documentation for the
+particular device drivers.
+
+The floppy imposes a very high interrupt load on the CPU, approx 30K/s.
+When something blocks interrupts (HD) it will loose some of them, so far 
+this is not known to have caused any data loss. On hihgly loaded systems
+it can make the floppy very slow. Other Q40 OS' simply poll the floppy
+for this reason - something that can't be done in Linux.
+Only possible cure is getting a 82072 contoler with fifo instead of 
+the 8272A
+
+drivers used by the Q40, appart from the very obvious (console etc.):
+	drivers/char/q40_keyb.c		# use PC keymaps for national keyboards
+		     serial.c		# normal PC driver - any speed
+	             lp.c		# printer driver
+		char/joystick/*		# most of this should work
+	        block/q40ide.c		# startup for ide
+		      ide*		# see Documentation/ide.txt
+		      floppy.c		# normal PC driver, DMA emu in asm/floppy.h
+					# and arch/m68k/kernel/entry.S
+					# see drivers/block/README.fd
+		video/q40fb.c
+		misc/parport_pc.c
+
+Various other PC drivers can be enabled simply by adding them to 
+arch/m68k/config.in, especially 8 bit devices should be without any
+problems. For cards using 16bit io/mem more care is required, like 
+checking byteorder issues, hacking memcpy_*_io etc.
+
+
+Debugging
+=========
+
+Upon startup the kernel will usually output "ABCQGHIJ" into the SRAM, 
+preceded by the booter signature. This is a trace just in case something 
+went wrong during earliest setup stages. 
+*Changed* to preserve SRAM contents by default, this is only done when 
+requested - SRAM must start with '%LX$' signature to do this. '-d' option 
+to 'lxx' loader enables this.
+
+SRAM can also be used as additional console device, use debug=mem.
+This will save kernel startup msgs into SRAM, the screen will display 
+only the penguin - and shell prompt if it gets that far..
+
+Serial console works and can also be used for debugging, provided serial
+initialisation works.
+
+Most problems seem to be caused by fawlty or badly configured io-cards or 
+harddrives anyway..there are so many things that can go wrong here.
+Make sure to configure the parallel port as SPP for first testing..the
+Q40 may have trouble with parallel interrupts.
+
+
+Q40 Hardware Description
+========================
+
+This is just an overview, see asm-m68k/* for details ask if you have any 
+questions.
+
+The Q40 consists of a 68040@40 MHz, 1MB video RAM, up to 32MB RAM, AT-style
+keyboard interface, 1 Programmable LED, 2 8bit DACs and up to 1MB ROM, 1MB
+shadow ROM.
+
+Most interfacing like floppy, hd, serial, parallel ports is done via ISA 
+slots. The ISA io and mem range is mapped (sparse&byteswapped!) into separate 
+regions of the memory.
+The main interrupt register IIRQ_REG will indicate whether an IRQ was internal 
+or from some ISA devices, EIRQ_REG can distinguish up to 8 ISA IRQs.
+
+The Q40 custom chip is programmable to provide 2 periodic timers:
+	- 50 or 200 Hz - level 2,  !!THIS CANT BE DISABLED!!
+	- 10 or 20 KHz - level 4 (and possibly 6 - hardware decoding..)
+
+Linux uses the 200 Hz interrupt for timer and beep by default.
+
+
+Interrupts
+==========
+
+q40 master chip handles only level triggered interrupts :-((
+further limitation is no disabling etc. Unless someone finds 
+some ingenious clue this means autoprobing will never work.
+Parallel port interrupts cause most trouble..
+
+IRQ sharing is not yet implemented.
+
+
+Keyboard
+========
+
+q40 receives AT make/break codes from the keyboard, these are translated to
+the PC scancodes x86 Linux uses. So by theory every national keyboard should
+work just by loading the apropriate x86 keytable - see any national-HOWTO.
+
+Unfortunately the AT->PC translation isn't quite trivial and even worse, my 
+documentation of it is absolutely minimal - thus some exotic keys may not 
+behave exactly as expected.
+
+There is still hope that it can be fixed completely though. If you encounter 
+problems, email me idealy this:
+	- exact keypress/release sequence
+	- 'showkey -s' run on q40, non-X session
+	- 'showkey -s' run on a PC, non-X session
+	- AT codes as displayed by the q40 debuging ROM
+btw if the showkey output from PC and Q40 doesn't differ then you have some
+classic configuration problem - don't send me anything in this case
+