mac80211: pass dtim_period to low level driver

This patch adds the dtim_period in ieee80211_bss_conf, this allows the low
level driver to know the dtim_period, and to plan power save accordingly.
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/linux/ieee80211.h

@@ -506,6 +506,19 @@ struct ieee80211_channel_sw_ie {
 	u8 count;
 } __attribute__ ((packed));
 
+/**
+ * struct ieee80211_tim
+ *
+ * This structure refers to "Traffic Indication Map information element"
+ */
+struct ieee80211_tim_ie {
+	u8 dtim_count;
+	u8 dtim_period;
+	u8 bitmap_ctrl;
+	/* variable size: 1 - 251 bytes */
+	u8 virtual_map[0];
+} __attribute__ ((packed));
+
 struct ieee80211_mgmt {
 	__le16 frame_control;
 	__le16 duration;

include/net/mac80211.h

@@ -177,9 +177,10 @@ enum ieee80211_bss_change {
  * @aid: association ID number, valid only when @assoc is true
  * @use_cts_prot: use CTS protection
  * @use_short_preamble: use 802.11b short preamble
+ * @dtim_period: num of beacons before the next DTIM, for PSM
  * @timestamp: beacon timestamp
  * @beacon_int: beacon interval
- * @assoc_capability: capabbilities taken from assoc resp
+ * @assoc_capability: capabilities taken from assoc resp
  * @assoc_ht: association in HT mode
  * @ht_conf: ht capabilities
  * @ht_bss_conf: ht extended capabilities
@@ -191,6 +192,7 @@ struct ieee80211_bss_conf {
 	/* erp related data */
 	bool use_cts_prot;
 	bool use_short_preamble;
+	u8 dtim_period;
 	u16 beacon_int;
 	u16 assoc_capability;
 	u64 timestamp;

net/mac80211/ieee80211_i.h

@@ -82,6 +82,7 @@ struct ieee80211_sta_bss {
 
 	u8 bssid[ETH_ALEN];
 	u8 ssid[IEEE80211_MAX_SSID_LEN];
+	u8 dtim_period;
 	u16 capability; /* host byte order */
 	enum ieee80211_band band;
 	int freq;

net/mac80211/mlme.c

@@ -551,6 +551,7 @@ static void ieee80211_set_associated(struct net_device *dev,
 			/* set timing information */
 			sdata->bss_conf.beacon_int = bss->beacon_int;
 			sdata->bss_conf.timestamp = bss->timestamp;
+			sdata->bss_conf.dtim_period = bss->dtim_period;
 
 			changed |= ieee80211_handle_bss_capability(sdata, bss);
 
@@ -2688,6 +2689,16 @@ static void ieee80211_rx_bss_info(struct net_device *dev,
 	bss->beacon_int = le16_to_cpu(mgmt->u.beacon.beacon_int);
 	bss->capability = le16_to_cpu(mgmt->u.beacon.capab_info);
 
+	if (elems->tim) {
+		struct ieee80211_tim_ie *tim_ie =
+			(struct ieee80211_tim_ie *)elems->tim;
+		bss->dtim_period = tim_ie->dtim_period;
+	}
+
+	/* set default value for buggy APs */
+	if (!elems->tim || bss->dtim_period == 0)
+		bss->dtim_period = 1;
+
 	bss->supp_rates_len = 0;
 	if (elems->supp_rates) {
 		clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;