Kernel-3.10.0-957.el7_zorro

    Writing Device Drivers for Zorro Devices
    ----------------------------------------

Written by Geert Uytterhoeven geert@linux-m68k.org
Last revised: September 5, 2003

1. Introduction

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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

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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

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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()
release_mem_region()

Shortcuts to claim the whole device’s address space are provided as well:

zorro_request_device
zorro_release_device

4. Accessing the Zorro Address Space

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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 z_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 z_ioremap() first
  before it can be accessed:

  virt_addr = z_ioremap(bus_addr, size);
  …
  z_iounmap(virt_addr);

5. References

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linux/include/linux/zorro.h
linux/include/asm-{m68k,ppc}/zorro.h
linux/include/linux/zorro_ids.h
linux/drivers/zorro
/proc/bus/zorro