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author | David Vrabel <david.vrabel@csr.com> | 2008-10-20 11:07:19 -0400 |
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committer | David Vrabel <david.vrabel@csr.com> | 2008-10-20 11:07:19 -0400 |
commit | 61e0e79ee3c609eb34edf2fe023708cba6a79b1f (patch) | |
tree | 663deacffd4071120dc9badb70428fe5f124c7b9 /Documentation/networking/regulatory.txt | |
parent | c15895ef30c2c03e99802951787183039a349d32 (diff) | |
parent | 0cfd81031a26717fe14380d18275f8e217571615 (diff) |
Merge branch 'master' into for-upstream
Conflicts:
Documentation/ABI/testing/sysfs-bus-usb
drivers/Makefile
Diffstat (limited to 'Documentation/networking/regulatory.txt')
-rw-r--r-- | Documentation/networking/regulatory.txt | 194 |
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diff --git a/Documentation/networking/regulatory.txt b/Documentation/networking/regulatory.txt new file mode 100644 index 000000000000..a96989a8ff35 --- /dev/null +++ b/Documentation/networking/regulatory.txt | |||
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1 | Linux wireless regulatory documentation | ||
2 | --------------------------------------- | ||
3 | |||
4 | This document gives a brief review over how the Linux wireless | ||
5 | regulatory infrastructure works. | ||
6 | |||
7 | More up to date information can be obtained at the project's web page: | ||
8 | |||
9 | http://wireless.kernel.org/en/developers/Regulatory | ||
10 | |||
11 | Keeping regulatory domains in userspace | ||
12 | --------------------------------------- | ||
13 | |||
14 | Due to the dynamic nature of regulatory domains we keep them | ||
15 | in userspace and provide a framework for userspace to upload | ||
16 | to the kernel one regulatory domain to be used as the central | ||
17 | core regulatory domain all wireless devices should adhere to. | ||
18 | |||
19 | How to get regulatory domains to the kernel | ||
20 | ------------------------------------------- | ||
21 | |||
22 | Userspace gets a regulatory domain in the kernel by having | ||
23 | a userspace agent build it and send it via nl80211. Only | ||
24 | expected regulatory domains will be respected by the kernel. | ||
25 | |||
26 | A currently available userspace agent which can accomplish this | ||
27 | is CRDA - central regulatory domain agent. Its documented here: | ||
28 | |||
29 | http://wireless.kernel.org/en/developers/Regulatory/CRDA | ||
30 | |||
31 | Essentially the kernel will send a udev event when it knows | ||
32 | it needs a new regulatory domain. A udev rule can be put in place | ||
33 | to trigger crda to send the respective regulatory domain for a | ||
34 | specific ISO/IEC 3166 alpha2. | ||
35 | |||
36 | Below is an example udev rule which can be used: | ||
37 | |||
38 | # Example file, should be put in /etc/udev/rules.d/regulatory.rules | ||
39 | KERNEL=="regulatory*", ACTION=="change", SUBSYSTEM=="platform", RUN+="/sbin/crda" | ||
40 | |||
41 | The alpha2 is passed as an environment variable under the variable COUNTRY. | ||
42 | |||
43 | Who asks for regulatory domains? | ||
44 | -------------------------------- | ||
45 | |||
46 | * Users | ||
47 | |||
48 | Users can use iw: | ||
49 | |||
50 | http://wireless.kernel.org/en/users/Documentation/iw | ||
51 | |||
52 | An example: | ||
53 | |||
54 | # set regulatory domain to "Costa Rica" | ||
55 | iw reg set CR | ||
56 | |||
57 | This will request the kernel to set the regulatory domain to | ||
58 | the specificied alpha2. The kernel in turn will then ask userspace | ||
59 | to provide a regulatory domain for the alpha2 specified by the user | ||
60 | by sending a uevent. | ||
61 | |||
62 | * Wireless subsystems for Country Information elements | ||
63 | |||
64 | The kernel will send a uevent to inform userspace a new | ||
65 | regulatory domain is required. More on this to be added | ||
66 | as its integration is added. | ||
67 | |||
68 | * Drivers | ||
69 | |||
70 | If drivers determine they need a specific regulatory domain | ||
71 | set they can inform the wireless core using regulatory_hint(). | ||
72 | They have two options -- they either provide an alpha2 so that | ||
73 | crda can provide back a regulatory domain for that country or | ||
74 | they can build their own regulatory domain based on internal | ||
75 | custom knowledge so the wireless core can respect it. | ||
76 | |||
77 | *Most* drivers will rely on the first mechanism of providing a | ||
78 | regulatory hint with an alpha2. For these drivers there is an additional | ||
79 | check that can be used to ensure compliance based on custom EEPROM | ||
80 | regulatory data. This additional check can be used by drivers by | ||
81 | registering on its struct wiphy a reg_notifier() callback. This notifier | ||
82 | is called when the core's regulatory domain has been changed. The driver | ||
83 | can use this to review the changes made and also review who made them | ||
84 | (driver, user, country IE) and determine what to allow based on its | ||
85 | internal EEPROM data. Devices drivers wishing to be capable of world | ||
86 | roaming should use this callback. More on world roaming will be | ||
87 | added to this document when its support is enabled. | ||
88 | |||
89 | Device drivers who provide their own built regulatory domain | ||
90 | do not need a callback as the channels registered by them are | ||
91 | the only ones that will be allowed and therefore *additional* | ||
92 | cannels cannot be enabled. | ||
93 | |||
94 | Example code - drivers hinting an alpha2: | ||
95 | ------------------------------------------ | ||
96 | |||
97 | This example comes from the zd1211rw device driver. You can start | ||
98 | by having a mapping of your device's EEPROM country/regulatory | ||
99 | domain value to to a specific alpha2 as follows: | ||
100 | |||
101 | static struct zd_reg_alpha2_map reg_alpha2_map[] = { | ||
102 | { ZD_REGDOMAIN_FCC, "US" }, | ||
103 | { ZD_REGDOMAIN_IC, "CA" }, | ||
104 | { ZD_REGDOMAIN_ETSI, "DE" }, /* Generic ETSI, use most restrictive */ | ||
105 | { ZD_REGDOMAIN_JAPAN, "JP" }, | ||
106 | { ZD_REGDOMAIN_JAPAN_ADD, "JP" }, | ||
107 | { ZD_REGDOMAIN_SPAIN, "ES" }, | ||
108 | { ZD_REGDOMAIN_FRANCE, "FR" }, | ||
109 | |||
110 | Then you can define a routine to map your read EEPROM value to an alpha2, | ||
111 | as follows: | ||
112 | |||
113 | static int zd_reg2alpha2(u8 regdomain, char *alpha2) | ||
114 | { | ||
115 | unsigned int i; | ||
116 | struct zd_reg_alpha2_map *reg_map; | ||
117 | for (i = 0; i < ARRAY_SIZE(reg_alpha2_map); i++) { | ||
118 | reg_map = ®_alpha2_map[i]; | ||
119 | if (regdomain == reg_map->reg) { | ||
120 | alpha2[0] = reg_map->alpha2[0]; | ||
121 | alpha2[1] = reg_map->alpha2[1]; | ||
122 | return 0; | ||
123 | } | ||
124 | } | ||
125 | return 1; | ||
126 | } | ||
127 | |||
128 | Lastly, you can then hint to the core of your discovered alpha2, if a match | ||
129 | was found. You need to do this after you have registered your wiphy. You | ||
130 | are expected to do this during initialization. | ||
131 | |||
132 | r = zd_reg2alpha2(mac->regdomain, alpha2); | ||
133 | if (!r) | ||
134 | regulatory_hint(hw->wiphy, alpha2, NULL); | ||
135 | |||
136 | Example code - drivers providing a built in regulatory domain: | ||
137 | -------------------------------------------------------------- | ||
138 | |||
139 | If you have regulatory information you can obtain from your | ||
140 | driver and you *need* to use this we let you build a regulatory domain | ||
141 | structure and pass it to the wireless core. To do this you should | ||
142 | kmalloc() a structure big enough to hold your regulatory domain | ||
143 | structure and you should then fill it with your data. Finally you simply | ||
144 | call regulatory_hint() with the regulatory domain structure in it. | ||
145 | |||
146 | Bellow is a simple example, with a regulatory domain cached using the stack. | ||
147 | Your implementation may vary (read EEPROM cache instead, for example). | ||
148 | |||
149 | Example cache of some regulatory domain | ||
150 | |||
151 | struct ieee80211_regdomain mydriver_jp_regdom = { | ||
152 | .n_reg_rules = 3, | ||
153 | .alpha2 = "JP", | ||
154 | //.alpha2 = "99", /* If I have no alpha2 to map it to */ | ||
155 | .reg_rules = { | ||
156 | /* IEEE 802.11b/g, channels 1..14 */ | ||
157 | REG_RULE(2412-20, 2484+20, 40, 6, 20, 0), | ||
158 | /* IEEE 802.11a, channels 34..48 */ | ||
159 | REG_RULE(5170-20, 5240+20, 40, 6, 20, | ||
160 | NL80211_RRF_PASSIVE_SCAN), | ||
161 | /* IEEE 802.11a, channels 52..64 */ | ||
162 | REG_RULE(5260-20, 5320+20, 40, 6, 20, | ||
163 | NL80211_RRF_NO_IBSS | | ||
164 | NL80211_RRF_DFS), | ||
165 | } | ||
166 | }; | ||
167 | |||
168 | Then in some part of your code after your wiphy has been registered: | ||
169 | |||
170 | int r; | ||
171 | struct ieee80211_regdomain *rd; | ||
172 | int size_of_regd; | ||
173 | int num_rules = mydriver_jp_regdom.n_reg_rules; | ||
174 | unsigned int i; | ||
175 | |||
176 | size_of_regd = sizeof(struct ieee80211_regdomain) + | ||
177 | (num_rules * sizeof(struct ieee80211_reg_rule)); | ||
178 | |||
179 | rd = kzalloc(size_of_regd, GFP_KERNEL); | ||
180 | if (!rd) | ||
181 | return -ENOMEM; | ||
182 | |||
183 | memcpy(rd, &mydriver_jp_regdom, sizeof(struct ieee80211_regdomain)); | ||
184 | |||
185 | for (i=0; i < num_rules; i++) { | ||
186 | memcpy(&rd->reg_rules[i], &mydriver_jp_regdom.reg_rules[i], | ||
187 | sizeof(struct ieee80211_reg_rule)); | ||
188 | } | ||
189 | r = regulatory_hint(hw->wiphy, NULL, rd); | ||
190 | if (r) { | ||
191 | kfree(rd); | ||
192 | return r; | ||
193 | } | ||
194 | |||