cfg80211: module_param to disable HT40 in 2.4GHz band

Currently mac80211 uses ieee80211_disable_40mhz_24ghz module
parameter to allow disabling 40MHz operation in the 2.4GHz band.
Move this handling from mac80211 to cfg80211 so that the feature
will be more generic.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/net/wireless/core.c b/net/wireless/core.c
index fe01de29bfe8..bbf1fa11107a 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -46,6 +46,11 @@ static struct dentry *ieee80211_debugfs_dir;
 /* for the cleanup, scan and event works */
 struct workqueue_struct *cfg80211_wq;
 
+static bool cfg80211_disable_40mhz_24ghz;
+module_param(cfg80211_disable_40mhz_24ghz, bool, 0644);
+MODULE_PARM_DESC(cfg80211_disable_40mhz_24ghz,
+                 "Disable 40MHz support in the 2.4GHz band");
+
 /* requires cfg80211_mutex to be held! */
 struct cfg80211_registered_device *cfg80211_rdev_by_wiphy_idx(int wiphy_idx)
 {
@@ -451,6 +456,18 @@ int wiphy_register(struct wiphy *wiphy)
                         return -EINVAL;
 
                 /*
+                 * Since cfg80211_disable_40mhz_24ghz is global, we can
+                 * modify the sband's ht data even if the driver uses a
+                 * global structure for that.
+                 */
+                if (cfg80211_disable_40mhz_24ghz &&
+                    band == IEEE80211_BAND_2GHZ &&
+                    sband->ht_cap.ht_supported) {
+                        sband->ht_cap.cap &= ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;
+                        sband->ht_cap.cap &= ~IEEE80211_HT_CAP_SGI_40;
+                }
+
+                /*
                  * Since we use a u32 for rate bitmaps in
                  * ieee80211_get_response_rate, we cannot
                  * have more than 32 legacy rates.