FreeBSD/Linux Kernel Cross Reference
sys/Documentation/zorro.txt

                     Writing Device Drivers for Zorro Devices
                     ----------------------------------------
     
     Written by Geert Uytterhoeven <geert@linux-m68k.org>
     Last revised: February 27, 2000
     
     
     1. Introduction
     ---------------
    
    The Zorro bus is the bus used in the Amiga family of computers. Thanks to
    AutoConfig(tm), it's 100% Plug-and-Play.
    
    There are two types of Zorro busses, Zorro II and Zorro III:
    
      - The Zorro II address space is 24-bit and lies within the first 16 MB of the
        Amiga's address map.
    
      - Zorro III is a 32-bit extension of Zorro II, which is backwards compatible
        with Zorro II. The Zorro III address space lies outside the first 16 MB.
    
    
    2. Probing for Zorro Devices
    ----------------------------
    
    Zorro devices are found by calling `zorro_find_device()', which returns a
    pointer to the `next' Zorro device with the specified Zorro ID. A probe loop
    for the board with Zorro ID `ZORRO_PROD_xxx' looks like:
    
        struct zorro_dev *z = NULL;
    
        while ((z = zorro_find_device(ZORRO_PROD_xxx, z))) {
            if (!zorro_request_region(z->resource.start+MY_START, MY_SIZE,
                                      "My explanation"))
            ...
        }
    
    `ZORRO_WILDCARD' acts as a wildcard and finds any Zorro device. If your driver
    supports different types of boards, you can use a construct like:
    
        struct zorro_dev *z = NULL;
    
        while ((z = zorro_find_device(ZORRO_WILDCARD, z))) {
            if (z->id != ZORRO_PROD_xxx1 && z->id != ZORRO_PROD_xxx2 && ...)
                continue;
            if (!zorro_request_region(z->resource.start+MY_START, MY_SIZE,
                                      "My explanation"))
            ...
        }
    
    
    3. Zorro Resources
    ------------------
    
    Before you can access a Zorro device's registers, you have to make sure it's
    not yet in use. This is done using the I/O memory space resource management
    functions:
    
        request_mem_region()
        check_mem_region()          (deprecated)
        release_mem_region()
    
    Shortcuts to claim the whole device's address space are provided as well:
    
        zorro_request_device
        zorro_check_device          (deprecated)
        zorro_release_device
    
    
    4. Accessing the Zorro Address Space
    ------------------------------------
    
    The address regions in the Zorro device resources are Zorro bus address
    regions. Due to the identity bus-physical address mapping on the Zorro bus,
    they are CPU physical addresses as well.
    
    The treatment of these regions depends on the type of Zorro space:
    
      - Zorro II address space is always mapped and does not have to be mapped
        explicitly using ioremap().
        
        Conversion from bus/physical Zorro II addresses to kernel virtual addresses
        and vice versa is done using:
    
            virt_addr = ZTWO_VADDR(bus_addr);
            bus_addr = ZTWO_PADDR(virt_addr);
    
      - Zorro III address space must be mapped explicitly using ioremap() first
        before it can be accessed:
     
            virt_addr = ioremap(bus_addr, size);
            ...
            iounmap(virt_addr);
    
    
    5. References
    -------------
    
    linux/include/linux/zorro.h
   linux/include/linux/ioport.h
   linux/include/asm-m68k/io.h
   linux/include/asm-m68k/amigahw.h
   linux/include/asm-ppc/io.h
   linux/drivers/zorro
   /proc/bus/zorro
   

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