103 lines
2.8 KiB
Plaintext
103 lines
2.8 KiB
Plaintext
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
|
|
|