Revision 4c882b019160ebd7e954ba787f6353ed69281fd7 authored by Benjamin Herrenschmidt on 14 January 2006, 05:35:35 UTC, committed by Paul Mackerras on 15 January 2006, 02:14:47 UTC
The changes to the device node structure broke Maple build. This fixes it. Unfortunately I coudn't test as my Maple board appears to be dead. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
1 parent 8385a6a
zorro.txt
Writing Device Drivers for Zorro Devices
----------------------------------------
Written by Geert Uytterhoeven <geert@linux-m68k.org>
Last revised: September 5, 2003
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()
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
------------------------------------
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
-------------
linux/include/linux/zorro.h
linux/include/asm-{m68k,ppc}/zorro.h
linux/include/linux/zorro_ids.h
linux/drivers/zorro
/proc/bus/zorro
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