Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/Documentation/zorro.txt
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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File size: 2886 byte(s)
Tag kernel26-2.6.12-alx-r9
1 | Writing Device Drivers for Zorro Devices |
2 | ---------------------------------------- |
3 | |
4 | Written by Geert Uytterhoeven <geert@linux-m68k.org> |
5 | Last revised: September 5, 2003 |
6 | |
7 | |
8 | 1. Introduction |
9 | --------------- |
10 | |
11 | The Zorro bus is the bus used in the Amiga family of computers. Thanks to |
12 | AutoConfig(tm), it's 100% Plug-and-Play. |
13 | |
14 | There are two types of Zorro busses, Zorro II and Zorro III: |
15 | |
16 | - The Zorro II address space is 24-bit and lies within the first 16 MB of the |
17 | Amiga's address map. |
18 | |
19 | - Zorro III is a 32-bit extension of Zorro II, which is backwards compatible |
20 | with Zorro II. The Zorro III address space lies outside the first 16 MB. |
21 | |
22 | |
23 | 2. Probing for Zorro Devices |
24 | ---------------------------- |
25 | |
26 | Zorro devices are found by calling `zorro_find_device()', which returns a |
27 | pointer to the `next' Zorro device with the specified Zorro ID. A probe loop |
28 | for the board with Zorro ID `ZORRO_PROD_xxx' looks like: |
29 | |
30 | struct zorro_dev *z = NULL; |
31 | |
32 | while ((z = zorro_find_device(ZORRO_PROD_xxx, z))) { |
33 | if (!zorro_request_region(z->resource.start+MY_START, MY_SIZE, |
34 | "My explanation")) |
35 | ... |
36 | } |
37 | |
38 | `ZORRO_WILDCARD' acts as a wildcard and finds any Zorro device. If your driver |
39 | supports different types of boards, you can use a construct like: |
40 | |
41 | struct zorro_dev *z = NULL; |
42 | |
43 | while ((z = zorro_find_device(ZORRO_WILDCARD, z))) { |
44 | if (z->id != ZORRO_PROD_xxx1 && z->id != ZORRO_PROD_xxx2 && ...) |
45 | continue; |
46 | if (!zorro_request_region(z->resource.start+MY_START, MY_SIZE, |
47 | "My explanation")) |
48 | ... |
49 | } |
50 | |
51 | |
52 | 3. Zorro Resources |
53 | ------------------ |
54 | |
55 | Before you can access a Zorro device's registers, you have to make sure it's |
56 | not yet in use. This is done using the I/O memory space resource management |
57 | functions: |
58 | |
59 | request_mem_region() |
60 | release_mem_region() |
61 | |
62 | Shortcuts to claim the whole device's address space are provided as well: |
63 | |
64 | zorro_request_device |
65 | zorro_release_device |
66 | |
67 | |
68 | 4. Accessing the Zorro Address Space |
69 | ------------------------------------ |
70 | |
71 | The address regions in the Zorro device resources are Zorro bus address |
72 | regions. Due to the identity bus-physical address mapping on the Zorro bus, |
73 | they are CPU physical addresses as well. |
74 | |
75 | The treatment of these regions depends on the type of Zorro space: |
76 | |
77 | - Zorro II address space is always mapped and does not have to be mapped |
78 | explicitly using z_ioremap(). |
79 | |
80 | Conversion from bus/physical Zorro II addresses to kernel virtual addresses |
81 | and vice versa is done using: |
82 | |
83 | virt_addr = ZTWO_VADDR(bus_addr); |
84 | bus_addr = ZTWO_PADDR(virt_addr); |
85 | |
86 | - Zorro III address space must be mapped explicitly using z_ioremap() first |
87 | before it can be accessed: |
88 | |
89 | virt_addr = z_ioremap(bus_addr, size); |
90 | ... |
91 | z_iounmap(virt_addr); |
92 | |
93 | |
94 | 5. References |
95 | ------------- |
96 | |
97 | linux/include/linux/zorro.h |
98 | linux/include/asm-{m68k,ppc}/zorro.h |
99 | linux/include/linux/zorro_ids.h |
100 | linux/drivers/zorro |
101 | /proc/bus/zorro |
102 |