Annotation of wikisrc/users/rkujawa/g-rex.mdwn, revision 1.6
1.1 rkujawa 1: [[!meta title="G-REX"]]
2:
3: Programming the G-REX PCI bridge
1.2 rkujawa 4:
1.5 rkujawa 5: document version 0.2 - THIS IS A WORK IN PROGRESS!
1.1 rkujawa 6:
7: # 0. Introduction
8:
1.4 rkujawa 9: This document describes software/hardware interface of the G-REX PCI bridge
10: for Amiga computers. What you're reading is a result of reverse engineering,
11: which was long and difficult process.
12:
13: Next time when you're going to buy a hardware product for your Amiga, don't
14: forget to ask the vendor to make the programming documentation publicly
15: available! Remeber that hardware without software is just a piece of junk...
1.1 rkujawa 16: and you can't write software without hardware documentation.
17:
18: In case you've noticed an error in this document please let me know.
19:
20: # 1. Theory of operation
21:
1.3 rkujawa 22: G-REX is an evolution of PCI bridge used previously on CyberVisionPPC and
23: BlizzardVisionPPC cards. These products share a lot of similiarities (at
1.4 rkujawa 24: least when it comes to PCI interface). In fact CVPPC/BVPPC can be treated as
25: a special one-slot version of G-REX. Maybe actually it's the other way around
26: ;-).
1.3 rkujawa 27:
28: Firmware does the dirty job of assigning PCI resources (BARs, interrupt lines,
29: etc.) before the OS is running. Therefore G-REX does not need any special
30: initialization.
1.1 rkujawa 31:
1.5 rkujawa 32: All memory spaces of G-REX are directly visible and addressable in Amiga memory
33: space, unlike in Mediator. Firmware allocates memory space as needed, depending
34: on what cards are installed.
35:
1.1 rkujawa 36: # 2. Memory map
37:
1.3 rkujawa 38: G-REX is configured as multipie AutoConf boards. Confusingly, they all have the same vendor (8512) and product (101).
1.1 rkujawa 39:
40: 0xFFFA0000 - PCI I/O register space, 64KB.
1.2 rkujawa 41:
1.1 rkujawa 42: 0xFFFC0000 - PCI configuration space, 128KB.
1.2 rkujawa 43:
1.1 rkujawa 44: 0xFFFE0000 - Bridge configuration registers, 4kB.
45:
46: 0x80000000 - PCI memory space, variable size and number of boards, depending on cards installed.
47:
1.4 rkujawa 48: # 2a. PCI configuration space (0xFFFA0000)
1.1 rkujawa 49:
1.3 rkujawa 50: Access to configuration space is a bit tricky. Be warned that access to
51: addresses not used by G-REX generates bus error (esp. to configuration
52: locations which are unused because there is no card in the slot). Depending on
53: how these errors are supported in your OS, it may be important to trap them and
54: handle correctly.
1.1 rkujawa 55:
1.4 rkujawa 56: Configuration data for first slot seems to be accessible at offset +0x1000 (on
57: CVPPC/BVPPC there's aslo a mirror on +0x0).
1.1 rkujawa 58:
59: [TO BE COMPLETED]
60:
1.4 rkujawa 61: # 2b. PCI I/O registers space (0xFFFC0000)
1.1 rkujawa 62:
63: This space offers access to I/O registers of all PCI cards.
64:
1.5 rkujawa 65: On G-REX BAR addresses in this space are treated as absolute.
66:
67: On CVPPC/BVPPC BAR addresses in this space are treated as relative to
68: 0xFFFA0000. Card with I/O BAR set to 0x100 will actually be available
69: at 0xFFFA0100.
1.1 rkujawa 70:
1.4 rkujawa 71: # 2c. PCI memory space (0x80000000)
1.1 rkujawa 72:
1.3 rkujawa 73: This space offers access to memory (and memory-mapped registers) of PCI cards.
74: Each PCI memory BAR is assigned a separate AutoConf board during firmware
1.4 rkujawa 75: initialization.
76:
77: For example Voodoo 3, which has two 32MB memory BARs, will be visible as
78: two 8512/101 boards somewhere at 0x80000000 (or later).
1.1 rkujawa 79:
1.3 rkujawa 80: Addresses in this space are treated as absolute. Memory BAR register set to
1.5 rkujawa 81: 0x80000000 means it is configured at this address.
82:
83: On CVPPC/BVPPC this space is present at different address - 0xE0000000.
1.1 rkujawa 84:
85: # 2d. Bridge configuration registers
86:
87: Offset - meaning
1.3 rkujawa 88:
1.1 rkujawa 89: 0x0000 - Endianness swapper mode, write 0x02 to switch bridge into big endian mode
1.3 rkujawa 90:
1.1 rkujawa 91: 0x0010 - Interrupt enable, write 0x01 to enable interrupts (INT2 on Amiga side)
92:
1.6 ! rkujawa 93: No need to fiddle with these registers, as they've been already configured
! 94: properly by the firmware.
1.1 rkujawa 95:
1.5 rkujawa 96: # 3. Reconfiguring the bus
1.1 rkujawa 97:
1.3 rkujawa 98: If needed, it's possible to reconfigure bus just by writing new values into
99: configuration space. Keep in mind that any previously initialized chips will
100: need to be reset and initialized again (for example 3Dfx Voodoo 3, which is
1.1 rkujawa 101: initialized by the firmware so it can display early startup menu).
102:
103: # 4. Interrupts
104:
1.3 rkujawa 105: All interrupts are converted into Amiga INT2 interrupt. There's no such thing
1.5 rkujawa 106: as interrupt acknowledge register. However, there seems to be an interrupt
107: enable register (see "Bridge configuration registers" above).
1.1 rkujawa 108:
109: # 5. DMA
110:
1.5 rkujawa 111: The bridge is certainly capable of real busmaster DMA, but it needs further
112: reverse engineering.
1.1 rkujawa 113:
114: [TO BE COMPLETED]
115:
1.3 rkujawa 116: There were at least two different revisions of G-REX 1200. Later revision
1.5 rkujawa 117: probably does support DMA in first two slots. I'm not sure if it is possible
118: to detect revision of the G-REX in software.
1.1 rkujawa 119:
120: G-REX 4000D probably has busmaster DMA capability in all slots.
121:
122: # 6. Sample PCI bridge driver implementation
123:
1.3 rkujawa 124: The NetBSD [[p5pb|http://netbsd.gw.com/cgi-bin/man-cgi?p5pb+4.amiga+NetBSD-current]]
125: driver serves as an example driver implementation. It was written using the
126: same knowledge that went into this document.
127:
128: The driver consists of several files in [[src/sys/arch/amiga/pci|http://nxr.netbsd.org/xref/src/sys/arch/amiga/pci/]] directory.
129:
1.6 ! rkujawa 130: * p5membar.c - Dummy driver handling AutoConf resources.
! 131: * p5membarvar.h - Structures used by the p5membar.
! 132: * p5pb.c - Main driver code.
! 133: * p5pbreg.h - Inlcude file containing register locations.
! 134: * p5pbvar.h - Structures used by the p5pb.
1.3 rkujawa 135:
136: The p5pb does attach on top of p5bus, however p5membar drivers attach on top of zbus (since 8512/101 entries are seen as Zorro boards).
1.1 rkujawa 137:
1.4 rkujawa 138: # 7. Thanks
139:
140: [[AmiBay|http://www.amibay.com]] users d0pefish and ramborolf helped testing
141: early versions of p5pb driver. Without their help this document would not
142: exist.
143:
CVSweb for NetBSD wikisrc <wikimaster@NetBSD.org> software: FreeBSD-CVSweb
![[BACK]](/icons/back.gif){kind=icon}
Return to g-rex.mdwn CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [NetBSD Developer Wiki] / wikisrc / users / rkujawa