Wireless: limit allowed channels for regulatory reasons

Hi,

for regulatory reasons we need to limit the 5 GHz channels to 100 - 140.

Please add the hostap statement chanlist to L(UCI).

[renne]

e.g. Germany:

Channel	Frequency (GHz)	Allowed EIRP (mW)	Outdoor
36	5,180	200	No
40	5,200	200	No
44	5,220	200	No
48	5,240	200	No
52	5,260	200	No
56	5,280	200	No
60	5,300	200	No
64	5,320	200	No
100	5,500	1000	Yes
104	5,520	1000	Yes
108	5,540	1000	Yes
112	5,560	1000	Yes
116	5,580	1000	Yes
120	5,600	1000	Yes
124	5,620	1000	Yes
128	5,640	1000	Yes
132	5,660	1000	Yes
136	5,680	1000	Yes
140	5,700	1000	Yes
149	5,745	25	Yes
153	5,765	25	Yes
157	5,785	25	Yes
161	5,805	25	Yes
165	5,825	25	Yes
155-171		4000	Commercially licensed services only

The auto mode selects all channels between 36 and 149 which means you can only use 25 mW in auto mode.

The hostapd option chanlist allows to define allowed channels in auto mode (e.g. 36-64 or 100-140 or a list of channels e.g. 120,128,136). We would e.g. need to limit the operation to channels 100-140 for indoor/outdoor operation with 1000 mW EIRP.

I suggest to add an option Allowed channels in LUCI for 5 Ghz operation which converts to chanlist in the hostapd configuration.

The only dependency is to 5 GHz (802.11a/h/j/n/ac) mode.

[NilsRo]

Also needed for DFS channel selection. Without hostap cannot jump to another channel on radar detection which switches of Wifi

    option channel 'auto'
    option channels '136, 140, 132, 116, 112, 108, 104, 100'

https://github.com/openwrt/openwrt/issues/9864