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