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diff --git a/sys/doc/seagate.doc b/sys/doc/seagate.doc new file mode 100644 index 000000000000..b22f2c9bca4e --- /dev/null +++ b/sys/doc/seagate.doc @@ -0,0 +1,125 @@ +This is a low level driver for Seagate ST01/02, Future Domain TMC-885, TMC-950 +SCSI host adapter that uses Julian Elishers SCSI code. + +This driver is the result of looking at code written by the following people: + + Drew Eckhardt + Julian Elischer + Glen Overby + Gary Close + +Special thank to + + Robert Knier + +that made the fast blind transfer routines, and also helped with debugging. + +I am very grateful to these people. + + +Operating system requirements: + +This driver uses the latest version of Julian Elischers scsi code, available +at FreeBSD.cdrom.com in the file called newscsi3.tar.gz. The driver has been +tested on FreeBSD 1.1-BETA, FreeBSD 1.0.2, 386bsd 0.1. I don't know if will +work with NetBSD. (I hope it will.) + + +The hardware: + +The ST01/02, and Future Domain 950 are very simple SCSI controllers. They are +not busmastering, so the processor must do all transfers a la IDE. They support +blind transfer by adding wait states (up to a certain limit). Interrupt is +generated for reconnect and parity errors (maybe also for some other events). + +The card consists of one command port that writes to scsi control lines, reads +status lines, and a data port that read/writes to the 8 data lines. The address +decoding gives both data and control ports large memory areas to a single +port. This is used by the code. + +The ST01/02 differs from the FD950 in memory address location and SCSI id. + +Probing for the card: + +A card is recognized by comparing the BIOS signature with known signatures. A +new card may not be recognized if the BIOS signature has changed. Please send +new signatures to me. + +Driver function: + +A scsi command is sent to scsi_cmd function. The command is either placed in +the queue or an retryable message is returned. The routine may wait for +completion of the command depending on the supplied flags. A timer is started +for every command placed in the queue. The commands are added in the order they +are received. There is a possiblity to make all REQUEST SENSE commands be +queued before all other commands, but I dont think it is a good thing (Linux +do however use this). + +The card is mostly controlled by the sea_main function. It is called by +scsi_cmd, the interrupt routine, and the timeout routine. The sea_main routine +runs as long there are something to do (transfer data, issue queued commands, +and handle reconnected commands). + +The data transfers may be done in two different ways: Blind and polled +transfers. They differ in the way the driver does it handshaking with the +target. During a blind transfer, the driver code blindly transfers a block +of data without checking for changed phase. During polled transfers, the +phase is checked between every character transfered. The polled transfers +are always used for status information and command transfers. + +Because the card does not use dma in any way, there is no need to handle +physical addresses. There is no problem with the isa-bus address limit of +16MB, making bounce-buffers unnecessary. + +The data structures: + +Every card has a sea_data structure keeping the queues of commands waiting to +be issued, and commands currently disconnected. The type of card (Seagate or +Future Domain), data and control port addresses, scsi id, busy flags for all +possible targets, and interrupt vector for the card. + +Every scsi command to be issued are stored in a sea_scb structure. It contains +a flag describing status/error of the command, current data buffer position, +and number of bytes remaining to be transfered. + + +INSTALLATION + +1) Alter defines in /sys/i386/isa/seagate.c if you don't + want to use blind transfers and/or disconnects. Please note that + interrupts must be enabled on the board if disconnects are used. +2) Create a new config file in /sys/i386/conf containing defines for Julian's + scsi code (see GENERICAH or GENERICBT). Replace the aha or bt controller + with: + controller sea0 at isa? bio irq 5 iomem 0xC8000 iosiz 0x2000 vector seaintr +3) config, make depend, make, cp, shutdown -r + +You should now have a working kernel booted. + +I have tested the code on the following hardware: 386DX 24MHz 8MB AMI BIOS, +Maxtor 7120A IDE, Seagate ST02, Maxtor LXT340S scsi disk, SONY CDU-8003 cdrom, +(short test with) WANGTEK 6200HS DAT drive. + + +PROBLEMS + +I have had problems getting the ST02 boot using FreeBSD boot floppies. I think +is some problem with BIOS calls not working. It is unfortunately impossible to +disconnect the ST02 floppy controller. + +I have had problems getting the driver to talk to a 40 MB Seagate disk. I +don't have access to it any more, so I can't do any more checking on it. + +NOTE: The ST02 creates its own description of the disk attached. This is not +the same as the disk says. This translation problem may cause problems when +sharing a disk between both DOS and BSD. It is however not impossible. + + +/Kent + + +Kent Palmkvist +kentp@isy.liu.se + + +$Id: seagate.doc,v 1.1 1994/06/28 15:47:12 jkh Exp $ |