mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-26 01:50:54 +07:00
6d6486a0c5
Adjust the file for it to be properly parsed by Sphinx, adding it to the index of the book it belongs. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
210 lines
7.7 KiB
ReStructuredText
210 lines
7.7 KiB
ReStructuredText
=====================================
|
|
Amiga Buddha and Catweasel IDE Driver
|
|
=====================================
|
|
|
|
The Amiga Buddha and Catweasel IDE Driver (part of ide.c) was written by
|
|
Geert Uytterhoeven based on the following specifications:
|
|
|
|
------------------------------------------------------------------------
|
|
|
|
Register map of the Buddha IDE controller and the
|
|
Buddha-part of the Catweasel Zorro-II version
|
|
|
|
The Autoconfiguration has been implemented just as Commodore
|
|
described in their manuals, no tricks have been used (for
|
|
example leaving some address lines out of the equations...).
|
|
If you want to configure the board yourself (for example let
|
|
a Linux kernel configure the card), look at the Commodore
|
|
Docs. Reading the nibbles should give this information::
|
|
|
|
Vendor number: 4626 ($1212)
|
|
product number: 0 (42 for Catweasel Z-II)
|
|
Serial number: 0
|
|
Rom-vector: $1000
|
|
|
|
The card should be a Z-II board, size 64K, not for freemem
|
|
list, Rom-Vektor is valid, no second Autoconfig-board on the
|
|
same card, no space preference, supports "Shutup_forever".
|
|
|
|
Setting the base address should be done in two steps, just
|
|
as the Amiga Kickstart does: The lower nibble of the 8-Bit
|
|
address is written to $4a, then the whole Byte is written to
|
|
$48, while it doesn't matter how often you're writing to $4a
|
|
as long as $48 is not touched. After $48 has been written,
|
|
the whole card disappears from $e8 and is mapped to the new
|
|
address just written. Make sure $4a is written before $48,
|
|
otherwise your chance is only 1:16 to find the board :-).
|
|
|
|
The local memory-map is even active when mapped to $e8:
|
|
|
|
============== ===========================================
|
|
$0-$7e Autokonfig-space, see Z-II docs.
|
|
|
|
$80-$7fd reserved
|
|
|
|
$7fe Speed-select Register: Read & Write
|
|
(description see further down)
|
|
|
|
$800-$8ff IDE-Select 0 (Port 0, Register set 0)
|
|
|
|
$900-$9ff IDE-Select 1 (Port 0, Register set 1)
|
|
|
|
$a00-$aff IDE-Select 2 (Port 1, Register set 0)
|
|
|
|
$b00-$bff IDE-Select 3 (Port 1, Register set 1)
|
|
|
|
$c00-$cff IDE-Select 4 (Port 2, Register set 0,
|
|
Catweasel only!)
|
|
|
|
$d00-$dff IDE-Select 5 (Port 3, Register set 1,
|
|
Catweasel only!)
|
|
|
|
$e00-$eff local expansion port, on Catweasel Z-II the
|
|
Catweasel registers are also mapped here.
|
|
Never touch, use multidisk.device!
|
|
|
|
$f00 read only, Byte-access: Bit 7 shows the
|
|
level of the IRQ-line of IDE port 0.
|
|
|
|
$f01-$f3f mirror of $f00
|
|
|
|
$f40 read only, Byte-access: Bit 7 shows the
|
|
level of the IRQ-line of IDE port 1.
|
|
|
|
$f41-$f7f mirror of $f40
|
|
|
|
$f80 read only, Byte-access: Bit 7 shows the
|
|
level of the IRQ-line of IDE port 2.
|
|
(Catweasel only!)
|
|
|
|
$f81-$fbf mirror of $f80
|
|
|
|
$fc0 write-only: Writing any value to this
|
|
register enables IRQs to be passed from the
|
|
IDE ports to the Zorro bus. This mechanism
|
|
has been implemented to be compatible with
|
|
harddisks that are either defective or have
|
|
a buggy firmware and pull the IRQ line up
|
|
while starting up. If interrupts would
|
|
always be passed to the bus, the computer
|
|
might not start up. Once enabled, this flag
|
|
can not be disabled again. The level of the
|
|
flag can not be determined by software
|
|
(what for? Write to me if it's necessary!).
|
|
|
|
$fc1-$fff mirror of $fc0
|
|
|
|
$1000-$ffff Buddha-Rom with offset $1000 in the rom
|
|
chip. The addresses $0 to $fff of the rom
|
|
chip cannot be read. Rom is Byte-wide and
|
|
mapped to even addresses.
|
|
============== ===========================================
|
|
|
|
The IDE ports issue an INT2. You can read the level of the
|
|
IRQ-lines of the IDE-ports by reading from the three (two
|
|
for Buddha-only) registers $f00, $f40 and $f80. This way
|
|
more than one I/O request can be handled and you can easily
|
|
determine what driver has to serve the INT2. Buddha and
|
|
Catweasel expansion boards can issue an INT6. A separate
|
|
memory map is available for the I/O module and the sysop's
|
|
I/O module.
|
|
|
|
The IDE ports are fed by the address lines A2 to A4, just as
|
|
the Amiga 1200 and Amiga 4000 IDE ports are. This way
|
|
existing drivers can be easily ported to Buddha. A move.l
|
|
polls two words out of the same address of IDE port since
|
|
every word is mirrored once. movem is not possible, but
|
|
it's not necessary either, because you can only speedup
|
|
68000 systems with this technique. A 68020 system with
|
|
fastmem is faster with move.l.
|
|
|
|
If you're using the mirrored registers of the IDE-ports with
|
|
A6=1, the Buddha doesn't care about the speed that you have
|
|
selected in the speed register (see further down). With
|
|
A6=1 (for example $840 for port 0, register set 0), a 780ns
|
|
access is being made. These registers should be used for a
|
|
command access to the harddisk/CD-Rom, since command
|
|
accesses are Byte-wide and have to be made slower according
|
|
to the ATA-X3T9 manual.
|
|
|
|
Now for the speed-register: The register is byte-wide, and
|
|
only the upper three bits are used (Bits 7 to 5). Bit 4
|
|
must always be set to 1 to be compatible with later Buddha
|
|
versions (if I'll ever update this one). I presume that
|
|
I'll never use the lower four bits, but they have to be set
|
|
to 1 by definition.
|
|
|
|
The values in this table have to be shifted 5 bits to the
|
|
left and or'd with $1f (this sets the lower 5 bits).
|
|
|
|
All the timings have in common: Select and IOR/IOW rise at
|
|
the same time. IOR and IOW have a propagation delay of
|
|
about 30ns to the clocks on the Zorro bus, that's why the
|
|
values are no multiple of 71. One clock-cycle is 71ns long
|
|
(exactly 70,5 at 14,18 Mhz on PAL systems).
|
|
|
|
value 0 (Default after reset)
|
|
497ns Select (7 clock cycles) , IOR/IOW after 172ns (2 clock cycles)
|
|
(same timing as the Amiga 1200 does on it's IDE port without
|
|
accelerator card)
|
|
|
|
value 1
|
|
639ns Select (9 clock cycles), IOR/IOW after 243ns (3 clock cycles)
|
|
|
|
value 2
|
|
781ns Select (11 clock cycles), IOR/IOW after 314ns (4 clock cycles)
|
|
|
|
value 3
|
|
355ns Select (5 clock cycles), IOR/IOW after 101ns (1 clock cycle)
|
|
|
|
value 4
|
|
355ns Select (5 clock cycles), IOR/IOW after 172ns (2 clock cycles)
|
|
|
|
value 5
|
|
355ns Select (5 clock cycles), IOR/IOW after 243ns (3 clock cycles)
|
|
|
|
value 6
|
|
1065ns Select (15 clock cycles), IOR/IOW after 314ns (4 clock cycles)
|
|
|
|
value 7
|
|
355ns Select, (5 clock cycles), IOR/IOW after 101ns (1 clock cycle)
|
|
|
|
When accessing IDE registers with A6=1 (for example $84x),
|
|
the timing will always be mode 0 8-bit compatible, no matter
|
|
what you have selected in the speed register:
|
|
|
|
781ns select, IOR/IOW after 4 clock cycles (=314ns) aktive.
|
|
|
|
All the timings with a very short select-signal (the 355ns
|
|
fast accesses) depend on the accelerator card used in the
|
|
system: Sometimes two more clock cycles are inserted by the
|
|
bus interface, making the whole access 497ns long. This
|
|
doesn't affect the reliability of the controller nor the
|
|
performance of the card, since this doesn't happen very
|
|
often.
|
|
|
|
All the timings are calculated and only confirmed by
|
|
measurements that allowed me to count the clock cycles. If
|
|
the system is clocked by an oscillator other than 28,37516
|
|
Mhz (for example the NTSC-frequency 28,63636 Mhz), each
|
|
clock cycle is shortened to a bit less than 70ns (not worth
|
|
mentioning). You could think of a small performance boost
|
|
by overclocking the system, but you would either need a
|
|
multisync monitor, or a graphics card, and your internal
|
|
diskdrive would go crazy, that's why you shouldn't tune your
|
|
Amiga this way.
|
|
|
|
Giving you the possibility to write software that is
|
|
compatible with both the Buddha and the Catweasel Z-II, The
|
|
Buddha acts just like a Catweasel Z-II with no device
|
|
connected to the third IDE-port. The IRQ-register $f80
|
|
always shows a "no IRQ here" on the Buddha, and accesses to
|
|
the third IDE port are going into data's Nirwana on the
|
|
Buddha.
|
|
|
|
Jens Schönfeld february 19th, 1997
|
|
|
|
updated may 27th, 1997
|
|
|
|
eMail: sysop@nostlgic.tng.oche.de
|