0001 ========================================
0002 Writing Device Drivers for Zorro Devices
0003 ========================================
0004
0005 :Author: Written by Geert Uytterhoeven <geert@linux-m68k.org>
0006 :Last revised: September 5, 2003
0007
0008
0009 Introduction
0010 ------------
0011
0012 The Zorro bus is the bus used in the Amiga family of computers. Thanks to
0013 AutoConfig(tm), it's 100% Plug-and-Play.
0014
0015 There are two types of Zorro buses, Zorro II and Zorro III:
0016
0017 - The Zorro II address space is 24-bit and lies within the first 16 MB of the
0018 Amiga's address map.
0019
0020 - Zorro III is a 32-bit extension of Zorro II, which is backwards compatible
0021 with Zorro II. The Zorro III address space lies outside the first 16 MB.
0022
0023
0024 Probing for Zorro Devices
0025 -------------------------
0026
0027 Zorro devices are found by calling ``zorro_find_device()``, which returns a
0028 pointer to the ``next`` Zorro device with the specified Zorro ID. A probe loop
0029 for the board with Zorro ID ``ZORRO_PROD_xxx`` looks like::
0030
0031 struct zorro_dev *z = NULL;
0032
0033 while ((z = zorro_find_device(ZORRO_PROD_xxx, z))) {
0034 if (!zorro_request_region(z->resource.start+MY_START, MY_SIZE,
0035 "My explanation"))
0036 ...
0037 }
0038
0039 ``ZORRO_WILDCARD`` acts as a wildcard and finds any Zorro device. If your driver
0040 supports different types of boards, you can use a construct like::
0041
0042 struct zorro_dev *z = NULL;
0043
0044 while ((z = zorro_find_device(ZORRO_WILDCARD, z))) {
0045 if (z->id != ZORRO_PROD_xxx1 && z->id != ZORRO_PROD_xxx2 && ...)
0046 continue;
0047 if (!zorro_request_region(z->resource.start+MY_START, MY_SIZE,
0048 "My explanation"))
0049 ...
0050 }
0051
0052
0053 Zorro Resources
0054 ---------------
0055
0056 Before you can access a Zorro device's registers, you have to make sure it's
0057 not yet in use. This is done using the I/O memory space resource management
0058 functions::
0059
0060 request_mem_region()
0061 release_mem_region()
0062
0063 Shortcuts to claim the whole device's address space are provided as well::
0064
0065 zorro_request_device
0066 zorro_release_device
0067
0068
0069 Accessing the Zorro Address Space
0070 ---------------------------------
0071
0072 The address regions in the Zorro device resources are Zorro bus address
0073 regions. Due to the identity bus-physical address mapping on the Zorro bus,
0074 they are CPU physical addresses as well.
0075
0076 The treatment of these regions depends on the type of Zorro space:
0077
0078 - Zorro II address space is always mapped and does not have to be mapped
0079 explicitly using z_ioremap().
0080
0081 Conversion from bus/physical Zorro II addresses to kernel virtual addresses
0082 and vice versa is done using::
0083
0084 virt_addr = ZTWO_VADDR(bus_addr);
0085 bus_addr = ZTWO_PADDR(virt_addr);
0086
0087 - Zorro III address space must be mapped explicitly using z_ioremap() first
0088 before it can be accessed::
0089
0090 virt_addr = z_ioremap(bus_addr, size);
0091 ...
0092 z_iounmap(virt_addr);
0093
0094
0095 References
0096 ----------
0097
0098 #. linux/include/linux/zorro.h
0099 #. linux/include/uapi/linux/zorro.h
0100 #. linux/include/uapi/linux/zorro_ids.h
0101 #. linux/arch/m68k/include/asm/zorro.h
0102 #. linux/drivers/zorro
0103 #. /proc/bus/zorro
0104
