void rtl_swlps_beacon(struct ieee80211_hw *hw, void *data, unsigned int len)
{
	struct rtl_priv *rtlpriv = rtl_priv(hw);
	struct rtl_mac *mac = rtl_mac(rtl_priv(hw));
	struct ieee80211_hdr *hdr = data;
	struct ieee80211_tim_ie *tim_ie;
	u8 *tim;
	u8 tim_len;
	bool u_buffed;
	bool m_buffed;

	if (mac->opmode != NL80211_IFTYPE_STATION)
		return;

	if (!rtlpriv->psc.swctrl_lps)
		return;

	if (rtlpriv->mac80211.link_state != MAC80211_LINKED)
		return;

	if (!rtlpriv->psc.sw_ps_enabled)
		return;

	if (rtlpriv->psc.fwctrl_lps)
		return;

	if (likely(!(hw->conf.flags & IEEE80211_CONF_PS)))
		return;

	/* check if this really is a beacon */
	if (!ieee80211_is_beacon(hdr->frame_control))
		return;

	/* min. beacon length + FCS_LEN */
	if (len <= 40 + FCS_LEN)
		return;

	/* and only beacons from the associated BSSID, please */
	if (!ether_addr_equal_64bits(hdr->addr3, rtlpriv->mac80211.bssid))
		return;

	rtlpriv->psc.last_beacon = jiffies;

	tim = rtl_find_ie(data, len - FCS_LEN, WLAN_EID_TIM);
	if (!tim)
		return;

	if (tim[1] < sizeof(*tim_ie))
		return;

	tim_len = tim[1];
	tim_ie = (struct ieee80211_tim_ie *) &tim[2];

	if (!WARN_ON_ONCE(!hw->conf.ps_dtim_period))
		rtlpriv->psc.dtim_counter = tim_ie->dtim_count;

	/* Check whenever the PHY can be turned off again. */

	/* 1. What about buffered unicast traffic for our AID? */
	u_buffed = ieee80211_check_tim(tim_ie, tim_len,
				       rtlpriv->mac80211.assoc_id);

	/* 2. Maybe the AP wants to send multicast/broadcast data? */
	m_buffed = tim_ie->bitmap_ctrl & 0x01;
	rtlpriv->psc.multi_buffered = m_buffed;

	/* unicast will process by mac80211 through
	 * set ~IEEE80211_CONF_PS, So we just check
	 * multicast frames here */
	if (!m_buffed) {
		/* back to low-power land. and delay is
		 * prevent null power save frame tx fail */
		queue_delayed_work(rtlpriv->works.rtl_wq,
				   &rtlpriv->works.ps_work, MSECS(5));
	} else {
		RT_TRACE(rtlpriv, COMP_POWER, DBG_DMESG,
			 "u_bufferd: %x, m_buffered: %x\n", u_buffed, m_buffed);
	}
}
Unknown