threeeye
bc1d038eac
Squashed backup commit (no shallow-clone history issues) of xiaomi-mt6833-dev/kernel_xiaomi_mt6833 (lineage-23.2 branch, upstream commit 9eece662e) plus all fixes applied to get everpal_defconfig building clean against a modern (GCC 15.2.0) toolchain -- see the previous commit message on the lineage-23.2 branch (also in this repo history is not available here since this is a squashed snapshot; full incremental history lives in the local DL380 checkout and the upstream GitHub remote). Upstream: https://github.com/xiaomi-mt6833-dev/kernel_xiaomi_mt6833 (lineage-23.2)
105 lines
2.9 KiB
Plaintext
105 lines
2.9 KiB
Plaintext
========================================
|
|
Writing Device Drivers for Zorro Devices
|
|
========================================
|
|
|
|
:Author: Written by Geert Uytterhoeven <geert@linux-m68k.org>
|
|
:Last revised: September 5, 2003
|
|
|
|
|
|
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 buses, 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.
|
|
|
|
|
|
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"))
|
|
...
|
|
}
|
|
|
|
|
|
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
|
|
|
|
|
|
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);
|
|
|
|
|
|
References
|
|
----------
|
|
|
|
#. linux/include/linux/zorro.h
|
|
#. linux/include/uapi/linux/zorro.h
|
|
#. linux/include/uapi/linux/zorro_ids.h
|
|
#. linux/arch/m68k/include/asm/zorro.h
|
|
#. linux/drivers/zorro
|
|
#. /proc/bus/zorro
|
|
|