Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r227458, r226436:

- change "is is" to "is" or "it is"
- change "the the" to "the"
- other typo fixes

Approved by: lstewart

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Remove the now unneeded references to these DFS methods.

Sorry for the noise everyone.

Approved by: re (kib, blanket)

Introduce some more DFS related hooks, inspired both by local work
and the Atheros reference code.

The radar detection code needs to know what the current DFS domain is.
Since net80211 doesn't currently know this information, it's extracted
from the HAL regulatory domain information.

The specifics:

* add a new ath_dfs API hook, ath_dfs_init_radar_filters(), which
updates the radar filters whenever the regulatory domain changes.
* add HAL_DFS_DOMAIN which describes the currently configured DFS domain .
* add a new HAL internal variable which tracks the currently configured
HAL DFS domain.
* add a new HAL capability, HAL_CAP_DFS_DMN, which returns the currently
configured HAL DFS domain setting.
* update the HAL DFS domain setting whenever the channel setting is
updated.

Since this isn't currently used by any radar code, these should all
be no-ops for existing users.

Obtained from: Atheros
Submitted by: KBC Networks, sibridge
Approved by: re (kib, blanket)

Fix incorrect error reporting during the dfs ioctl function.

Approved by: re (kib)

Implement a basic radar parameter API in the dfs_null module.

Since no actual radar data is ever handled, this won't
do anything. It's mostly here as a reference for those who
wish to experiment with radar detection.

Approved by: re (kib)

Commit radar detection changes missed by my previous commit.

Flesh out the radar detection related operations for the ath driver.

This is in no way a complete DFS/radar detection implementation!
It merely creates an abstracted interface which allows for future
development of the DFS radar detection code.

Note: Net80211 already handles the bulk of the DFS machinery,
all we need to do here is figure out that a radar event has occured
and inform it as such. It then drives the DFS state engine for us.

The "null" DFS radar detection module is included by default;
it doesn't require a device line.

This commit:

* Adds a simple abstracted layer for radar detection state -
sys/dev/ath/ath_dfs/;
* Implements a null DFS module which doesn't do anything;
(ie, implements the exact behaviour at the moment);
* Adds hooks to the ath driver to process received radar events
and gives the DFS module a chance to determine whether
a radar has been detected.

Obtained from: Atheros