1 NCR 53C80/53C400 driver 2 3 BACKGROUND 4 ---------- 5 The NCR 53C80 SCSI Bus Controller (SBC) is an early single-chip solution 6 which formed the basis of many early SCSI host adapters for both the 7 i386 and m68k platforms. The NCR 53C400 is a slightly more advanced 8 chip which retains backward compatibility with the 53C80. 9 10 On the PC, the NCR 53C80 was most commonly used to implement simple, cheap 11 SCSI host adapters that were bundled with tape and CD-ROM drives. Since 12 these controllers were not bus-mastering (and in some cases were not even 13 interrupt-driven), they (like IDE adapters) required the CPU to perform 14 much of the actual processing. These days, these controllers are cheap 15 and plentiful since many are not supported by Windows 95. 16 17 Similarly, NetBSD, although it has had an MI 53C80 driver (used by the 18 Sun3 and Mac68k ports) for some time, has not had a i386 driver. 19 20 Until now, that is... 21 22 OVERVIEW 23 -------- 24 The NCR 53C80/53C400 driver (the 'nca' device) consists of two pieces: 25 26 1) Patches for the 53C80 MI driver to make it use bus_space() 27 functions. (This requires an optional define. By default, 28 the driver will compile in "legacy" memory-mapped mode. 29 30 2) A machine-dependent driver (nca) containing probe and 31 attachment routines. 32 33 This driver has bene tested with the following adapters: 34 35 NCS-250 (Chinon) 53C80, port-mapped, polled-mode 36 (This is used in my primary development 37 box to drive an external Zip drive.) 38 Sumo SCSI-AT 53C80, port-mapped, interrupt driven 39 (Note: This is an odd card in that its 40 own firmware seems to have trouble detecting 41 attached drives. Under NetBSD, however, 42 it operates with no problems.) 43 Trantor T-160 53C400, port-mapped, interrupt driven 44 This card was often bundled with NEC 45 CD-ROM drives. (My standalone test box 46 is using this as its primary adapter.) 47 DTC 3150V 53C400, memory-mapped, interrupt driven 48 This a simple card designed to drive 49 a CD-ROM. 50 51 CONFIGURATION 52 ------------- 53 To setup the nca driver, the configuration file must contain the following: 54 55 options NCR5380_USE_BUS_SPACE 56 57 This line is required to add bus_space() compatibility to the MI driver. 58 59 Next you need to add one or more configuration lines for the nca devices: 60 61 nca0 at isa? port 0x360 irq 15 62 nca1 at isa? iomem 0xd8000 irq 5 63 64 The first is for a port-mapped controller at 0x360, IRQ 15. The second line 65 is for a memory-mapped controller (Trantor T128 or equivalent) at 66 0xd800-0xdff, IRQ 5. 67 68 You can also set up the driver in "polled" mode (i.e., no interrupts) by 69 leaving off the "irq" portion of the line: 70 71 nca0 at isa? port 0x360 72 nca1 at isa? iomem 0xd8000 73 74 Lastly, you need to add a scsibus attachment line for the nca device: 75 76 scsibus* at nca? 77 78 The following is the probe output from my test system: 79 80 Copyright (c) 1996, 1997, 1998 81 The NetBSD Foundation, Inc. All rights reserved. 82 Copyright (c) 1982, 1986, 1989, 1991, 1993 83 The Regents of the University of California. All rights reserved. 84 85 NetBSD 1.3.2 (GENERIC) #2: Sun Oct 4 17:11:43 EDT 1998 86 root@hefalump:/usr/src/sys/arch/i386/compile/GENERIC 87 cpu0: Intel 486DX (486-class) 88 real mem = 7995392 89 avail mem = 5349376 90 using 123 buffers containing 503808 bytes of memory 91 mainbus0 (root) 92 isa0 at mainbus0 93 com1 at isa0 port 0x2f8-0x2ff irq 3: ns8250 or ns16450, no fifo 94 com2 at isa0 port 0x3e8-0x3ef irq 5: ns8250 or ns16450, no fifo 95 lpt0 at isa0 port 0x378-0x37b irq 7 96 nca0 at isa0 port 0x360-0x36f irq 15 97 nca0: NCR 53C400 detected 98 scsibus0 at nca0: 8 targets 99 sd0 at scsibus0 targ 0 lun 0: <HP, C2235, 0B11> SCSI2 0/direct fixed 100 sd0: 402MB, 1574 cyl, 9 head, 58 sec, 512 bytes/sect x 825012 sectors 101 cd0 at scsibus0 targ 6 lun 0: <CHINON, CD-ROM CDS-535, Q20> SCSI2 5/cdrom removable 102 nca1 at isa0 iomem 0xdb878-0xdb887 irq 5 103 nca1: NCR 53C400 detected 104 scsibus1 at nca1: 8 targets 105 sd1 at scsibus1 targ 5 lun 0: <IOMEGA, ZIP 100, J.02> SCSI2 0/direct removable 106 sd1: 96MB, 96 cyl, 64 head, 32 sec, 512 bytes/sect x 196608 sectors 107 npx0 at isa0 port 0xf0-0xff: using exception 16 108 pc0 at isa0 port 0x60-0x6f irq 1: color 109 pc0: console 110 fdc0 at isa0 port 0x3f0-0x3f7 irq 6 drq 2 111 fd0 at fdc0 drive 0: 1.44MB, 80 cyl, 2 head, 18 sec 112 biomask 8060 netmask 8460 ttymask 84e2 113 boot device: sd0 114 root on sd0a dumps on sd0b 115 root file system type: ffs 116 117 In this output, nca0 is a Trantor T-160 and nca1 is a DTC 3150V. Both happen 118 to be 53C400-based controllers. 119 120 LIMITATIONS 121 ----------- 122 As of this writing, the nca driver has two known limitations: 123 124 1) No DMA or pseudo-DMA support 125 126 This is unfortunate, but may be remedied in a later release. I would welcome 127 any help by someone more familiar with DMA, particularly in relation to 128 bus_space(). 129 130 As it is, however, performance of the nca driver is acceptable, though some 131 of that may depend on one's definition of "acceptable". Remember that these 132 were not high speed controller under the best conditions, so much of it is 133 really the nature of the beast. It should be adequate for tapes, CD-ROMS, 134 and low-usage disk devices (e.g., Zip drives). If you want to drive a CD-R 135 drive, then invest in an Adaptec 154X or a PCI controller. 136 137 2) No support for the SCSI port of the Pro AudioStudio 16. 138 139 This is also unfortunate and may not be able to be remedied within the 140 current framework of the bus_space() functions and the nca driver. 141 142 The problem is this: In most adapters, the eight 53C80 registers are mapped 143 to eight sequential locations, either ports or memory addresses. On the 144 PAS-16, however, the registers are mapped to two sets of ports- four 145 sequential ports at the base address and four sequential ports located 146 0x2000 higher. As I currently understand it, this is not supportable by 147 the current bus_space() implementation nor is it possible for the driver 148 to allocate a second bus_space_tag and _handle itself to accommodate the 149 second set of ports. Without either, it is very difficult to imagine how 150 a portable linkage to the MI driver could be made. 151 152 Again, I welcome suggestions. 153 154 HISTORY 155 ------- 156 An nca driver first appeared in FreeBSD. 157 158 This particular one borrows a little code from it and some from the i386 159 'esp' and sun3 'si' drivers. It, like many things in the free unix world, 160 was written because it solved a problem- mine! In my case, it was a need 161 of a SCSI card and a lack of IRQs. The good news was that I had one 162 (NCS-250); the bad news was that it was not supported under NetBSD. The 163 rest is history. 164 165 DISCLAIMER 166 ---------- 167 Like most things, you should take this code with a grain of salt. I have 168 tried to test it sufficiently, but it is always possible that it is not 169 compatible with some aspect of your system. If you end up suffering 170 massive data loss and destruction, you have my sympathies, but I do not 171 and will not allow myself to be held responsible. 172 173 CREDITS 174 ------- 175 My thanks to Jason Thorpe and the rest of the NetBSD team for making it 176 so easy to write this driver. My thanks also to the authors of the 177 FreeBSD nca driver for inspiration and 53C400 support. 178 179 In the end, I hope that someone else can find this driver as useful as I 180 have. If so, please drop me a line at jruschme (a] exit109.com and let me 181 know about it. 182 183 Share and enjoy 184 185 John Ruschmeyer (jruschme (a] exit109.com) 186 11 October 1998 187
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