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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/zorro.txt | |
download | linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz |
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'Documentation/zorro.txt')
-rw-r--r-- | Documentation/zorro.txt | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/Documentation/zorro.txt b/Documentation/zorro.txt new file mode 100644 index 000000000000..d5829d14774a --- /dev/null +++ b/Documentation/zorro.txt @@ -0,0 +1,102 @@ + 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 + |