Annotation of wikisrc/users/rkujawa/g-rex.mdwn, revision 1.7

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: 
1.7     ! rkujawa    22: G-REX is connected to local expansion slot present on CyberStorm PPC and 
        !            23: Blizzard PPC.  
        !            24: 
1.3       rkujawa    25: G-REX is an evolution of PCI bridge used previously on CyberVisionPPC and 
                     26: BlizzardVisionPPC cards. These products share a lot of similiarities (at 
1.4       rkujawa    27: least when it comes to PCI interface). In fact CVPPC/BVPPC can be treated as
                     28: a special one-slot version of G-REX. Maybe actually it's the other way around
                     29: ;-). 
1.3       rkujawa    30: 
                     31: Firmware does the dirty job of assigning PCI resources (BARs, interrupt lines, 
                     32: etc.) before the OS is running. Therefore G-REX does not need any special 
                     33: initialization.
1.1       rkujawa    34: 
1.5       rkujawa    35: All memory spaces of G-REX are directly visible and addressable in Amiga memory
                     36: space, unlike in Mediator. Firmware allocates memory space as needed, depending
                     37: on what cards are installed.
                     38: 
1.7     ! rkujawa    39: Blizzard PPC hardware revision 0 is not compatible with G-REX
        !            40: (which revisions are compatible?). 
        !            41: 
1.1       rkujawa    42: # 2. Memory map
                     43: 
1.7     ! rkujawa    44: G-REX is configured as multipie AutoConf boards. Confusingly, they all have the 
        !            45: same vendor (8512) and product (101).
1.1       rkujawa    46: 
                     47: 0xFFFA0000 - PCI I/O register space, 64KB.
1.2       rkujawa    48: 
1.1       rkujawa    49: 0xFFFC0000 - PCI configuration space, 128KB.
1.2       rkujawa    50: 
1.1       rkujawa    51: 0xFFFE0000 - Bridge configuration registers, 4kB.
                     52: 
                     53: 0x80000000 - PCI memory space, variable size and number of boards, depending on cards installed. 
                     54: 
1.4       rkujawa    55: # 2a. PCI configuration space (0xFFFA0000)
1.1       rkujawa    56: 
1.3       rkujawa    57: Access to configuration space is a bit tricky. Be warned that access to 
                     58: addresses not used by G-REX generates bus error (esp. to configuration 
                     59: locations which are unused because there is no card in the slot). Depending on 
                     60: how these errors are supported in your OS, it may be important to trap them and
                     61: handle correctly. 
1.1       rkujawa    62: 
1.4       rkujawa    63: Configuration data for first slot seems to be accessible at offset +0x1000 (on 
                     64: CVPPC/BVPPC there's aslo a mirror on +0x0).
1.1       rkujawa    65: 
                     66: [TO BE COMPLETED]
                     67: 
1.4       rkujawa    68: # 2b. PCI I/O registers space (0xFFFC0000)
1.1       rkujawa    69: 
                     70: This space offers access to I/O registers of all PCI cards.
                     71: 
1.5       rkujawa    72: On G-REX BAR addresses in this space are treated as absolute.
                     73: 
                     74: On CVPPC/BVPPC BAR addresses in this space are treated as relative to 
                     75: 0xFFFA0000. Card with I/O BAR set to 0x100 will actually be available 
                     76: at 0xFFFA0100. 
1.1       rkujawa    77: 
1.4       rkujawa    78: # 2c. PCI memory space (0x80000000)
1.1       rkujawa    79: 
1.3       rkujawa    80: This space offers access to memory (and memory-mapped registers) of PCI cards. 
                     81: Each PCI memory BAR is assigned a separate AutoConf board during firmware 
1.4       rkujawa    82: initialization.
                     83: 
                     84: For example Voodoo 3, which has two 32MB memory BARs, will be visible as 
                     85: two 8512/101 boards somewhere at 0x80000000 (or later).
1.1       rkujawa    86: 
1.3       rkujawa    87: Addresses in this space are treated as absolute. Memory BAR register set to 
1.5       rkujawa    88: 0x80000000 means it is configured at this address.
                     89: 
                     90: On CVPPC/BVPPC this space is present at different address - 0xE0000000.
1.1       rkujawa    91: 
                     92: # 2d. Bridge configuration registers
                     93: 
                     94: Offset - meaning
1.3       rkujawa    95: 
1.1       rkujawa    96: 0x0000 - Endianness swapper mode, write 0x02 to switch bridge into big endian mode
1.3       rkujawa    97: 
1.1       rkujawa    98: 0x0010 - Interrupt enable, write 0x01 to enable interrupts (INT2 on Amiga side)
                     99: 
1.6       rkujawa   100: No need to fiddle with these registers, as they've been already configured 
                    101: properly by the firmware.
1.1       rkujawa   102: 
1.7     ! rkujawa   103: # 3. Detecting the G-REX
        !           104: 
        !           105: Since AutoConf entries are created by the firmware, G-REX needs a special 
        !           106: firmware for CyberStorm PPC and Blizzard PPC. Known CSPPC firmware revisions 
        !           107: supporting G-REX include 44.69 and 44.71.
        !           108: 
        !           109: Detecting the G-REX is done by looking for Phase5 vendor ID (8512) and product
        !           110: ID 101. Keep in mind that there will be more than one such board present, as
        !           111: expained above.
        !           112: 
        !           113: It is possible to misdetect CVPPC/BVPPC as G-REX, since it uses the same vendor 
        !           114: and product ID if G-REX firmware is installed. With older firmware versions 
        !           115: these cards have no associated AutoConf entries.
        !           116: 
        !           117: Differentiating between CVPPC/BVPPC and G-REX in this situation is possible
        !           118: by looking for Texas Instruments TVP4020 vendor and product ID at the beginning
        !           119: of PCI configuration space. Configuration data for Permedia 2 chip will be
        !           120: available at offset 0x0 on CVPPC/BVPPC, but on G-REX first slot is located
        !           121: at offset 0x1000. See [[p5pb_identify_bridge()|http://nxr.netbsd.org/xref/src/sys/arch/amiga/pci/p5pb.c#p5pb_identify_bridge]] and [[p5pb_cvppc_probe()|http://nxr.netbsd.org/xref/src/sys/arch/amiga/pci/p5pb.c#p5pb_cvppc_probe]] functions
        !           122: in the NetBSD driver.
        !           123: 
        !           124: # 4. Reconfiguring the bus
1.1       rkujawa   125: 
1.3       rkujawa   126: If needed, it's possible to reconfigure bus just by writing new values into 
                    127: configuration space. Keep in mind that any previously initialized chips will 
                    128: need to be reset and initialized again (for example 3Dfx Voodoo 3, which is
1.1       rkujawa   129: initialized by the firmware so it can display early startup menu). 
                    130: 
1.7     ! rkujawa   131: # 5. Interrupts
1.1       rkujawa   132: 
1.3       rkujawa   133: All interrupts are converted into Amiga INT2 interrupt. There's no such thing 
1.5       rkujawa   134: as interrupt acknowledge register. However, there seems to be an interrupt 
                    135: enable register (see "Bridge configuration registers" above).
1.1       rkujawa   136: 
1.7     ! rkujawa   137: # 6. DMA
1.1       rkujawa   138: 
1.5       rkujawa   139: The bridge is certainly capable of real busmaster DMA, but it needs further 
                    140: reverse engineering.
1.1       rkujawa   141: 
                    142: [TO BE COMPLETED]
                    143: 
1.3       rkujawa   144: There were at least two different revisions of G-REX 1200. Later revision 
1.5       rkujawa   145: probably does support DMA in first two slots. I'm not sure if it is possible
                    146: to detect revision of the G-REX in software.
1.1       rkujawa   147: 
                    148: G-REX 4000D probably has busmaster DMA capability in all slots.
                    149: 
1.7     ! rkujawa   150: # 7. Sample PCI bridge driver implementation
1.1       rkujawa   151: 
1.3       rkujawa   152: The NetBSD [[p5pb|http://netbsd.gw.com/cgi-bin/man-cgi?p5pb+4.amiga+NetBSD-current]] 
                    153: driver serves as an example driver implementation. It was written using the 
                    154: same knowledge that went into this document.
                    155: 
                    156: The driver consists of several files in [[src/sys/arch/amiga/pci|http://nxr.netbsd.org/xref/src/sys/arch/amiga/pci/]] directory.
                    157: 
1.6       rkujawa   158: * p5membar.c - Dummy driver handling AutoConf resources.
                    159: * p5membarvar.h - Structures used by the p5membar.
                    160: * p5pb.c - Main driver code.
                    161: * p5pbreg.h - Inlcude file containing register locations.
                    162: * p5pbvar.h - Structures used by the p5pb.
1.3       rkujawa   163: 
                    164: 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   165: 
1.7     ! rkujawa   166: # 8. Thanks
1.4       rkujawa   167: 
                    168: [[AmiBay|http://www.amibay.com]] users d0pefish and ramborolf helped testing 
                    169: early versions of p5pb driver. Without their help this document would not 
                    170: exist.
                    171: 

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