Question

I’m writing a kernel module that needs to read the value of bitrate from this union :

union   iwreq_data
{
    .......
    struct iw_param bitrate;    /* default bit rate */

     ....
}

this code is taken form wireless.h anyone knows how I can access get its’ value?I mean what struct should I use net_device?wireless_dev? I’m using linux kernel 2.6.35

Answer 1

If you have union iwreq_data *data, you can simply use data->bitrate.value.

But this structure doesn’t permanently exist, so you can’t get a pointer to it for a given device. The structure is used when setting or getting parameters for a device, and exists only for the duration of the set/get operation.
When setting the bitrate, the driver saves the new value in a driver-dependent manner, and the structure is released (it’s normally allocated on the stack of the setting function).

You can try calling ieee80211softmac_wx_get_rate to get it. Give it a pointer to an uninitialized union iwreq_data, and it will fill in the bit rate.