p54: re-enable power save feature

This patch re-enables p54's power save features and adds a workaround
which temporarily alters the device's power state in order to allow
ps-polls to be sent and buffered data to be retrieved during psm.

(Incorporates patch originally posted as "p54: fix beacon template dtim
IE corruption". -- JWL)

Signed-off-by: Christian Lamparter <chunkeey@web.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

5 files changed, 98 insertions, 32 deletions

diff --git a/drivers/net/wireless/p54/fwio.c b/drivers/net/wireless/p54/fwio.c
index dc4f3f5ee0c8..349375f4a14b 100644
--- a/drivers/net/wireless/p54/fwio.c
+++ b/drivers/net/wireless/p54/fwio.c
@@ -585,7 +585,8 @@ int p54_set_ps(struct p54_common *priv)
         unsigned int i;
         u16 mode;
 
-        if (priv->hw->conf.flags & IEEE80211_CONF_PS)
+        if (priv->hw->conf.flags & IEEE80211_CONF_PS &&
+            !priv->powersave_override)
                 mode = P54_PSM | P54_PSM_BEACON_TIMEOUT | P54_PSM_DTIM |
                        P54_PSM_CHECKSUM | P54_PSM_MCBC;
         else
@@ -607,8 +608,8 @@ int p54_set_ps(struct p54_common *priv)
 
         psm->beacon_rssi_skip_max = 200;
         psm->rssi_delta_threshold = 0;
-        psm->nr = 10;
-        psm->exclude[0] = 0;
+        psm->nr = 1;
+        psm->exclude[0] = WLAN_EID_TIM;
 
         p54_tx(priv, skb);
         return 0;
diff --git a/drivers/net/wireless/p54/lmac.h b/drivers/net/wireless/p54/lmac.h
index 0496cff26b35..af35cfcd4fe3 100644
--- a/drivers/net/wireless/p54/lmac.h
+++ b/drivers/net/wireless/p54/lmac.h
@@ -548,4 +548,7 @@ int p54_upload_key(struct p54_common *priv, u8 algo, int slot,
 int p54_download_eeprom(struct p54_common *priv, void *buf,
                         u16 offset, u16 len);
 
+/* utility */
+u8 *p54_find_ie(struct sk_buff *skb, u8 ie);
+
 #endif /* LMAC_H */
diff --git a/drivers/net/wireless/p54/main.c b/drivers/net/wireless/p54/main.c
index f9b4f6a238ea..c9a054548d95 100644
--- a/drivers/net/wireless/p54/main.c
+++ b/drivers/net/wireless/p54/main.c
@@ -65,51 +65,64 @@ static int p54_set_tim(struct ieee80211_hw *dev, struct ieee80211_sta *sta,
         return p54_update_beacon_tim(priv, sta->aid, set);
 }
 
-static int p54_beacon_format_ie_tim(struct sk_buff *skb)
+u8 *p54_find_ie(struct sk_buff *skb, u8 ie)
 {
-        /*
-         * the good excuse for this mess is ... the firmware.
-         * The dummy TIM MUST be at the end of the beacon frame,
-         * because it'll be overwritten!
-         */
-
         struct ieee80211_mgmt *mgmt = (void *)skb->data;
         u8 *pos, *end;
 
         if (skb->len <= sizeof(mgmt))
-                return -EINVAL;
+                return NULL;
 
         pos = (u8 *)mgmt->u.beacon.variable;
         end = skb->data + skb->len;
         while (pos < end) {
                 if (pos + 2 + pos[1] > end)
-                        return -EINVAL;
+                        return NULL;
 
-                if (pos[0] == WLAN_EID_TIM) {
-                        u8 dtim_len = pos[1];
-                        u8 dtim_period = pos[3];
-                        u8 *next = pos + 2 + dtim_len;
+                if (pos[0] == ie)
+                        return pos;
 
-                        if (dtim_len < 3)
-                                return -EINVAL;
+                pos += 2 + pos[1];
+        }
+        return NULL;
+}
 
-                        memmove(pos, next, end - next);
+static int p54_beacon_format_ie_tim(struct sk_buff *skb)
+{
+        /*
+         * the good excuse for this mess is ... the firmware.
+         * The dummy TIM MUST be at the end of the beacon frame,
+         * because it'll be overwritten!
+         */
+        u8 *tim;
+        u8 dtim_len;
+        u8 dtim_period;
+        u8 *next;
 
-                        if (dtim_len > 3)
-                                skb_trim(skb, skb->len - (dtim_len - 3));
+        tim = p54_find_ie(skb, WLAN_EID_TIM);
+        if (!tim)
+                return 0;
 
-                        pos = end - (dtim_len + 2);
+        dtim_len = tim[1];
+        dtim_period = tim[3];
+        next = tim + 2 + dtim_len;
+
+        if (dtim_len < 3)
+                return -EINVAL;
+
+        memmove(tim, next, skb_tail_pointer(skb) - next);
+        tim = skb_tail_pointer(skb) - (dtim_len + 2);
+
+        /* add the dummy at the end */
+        tim[0] = WLAN_EID_TIM;
+        tim[1] = 3;
+        tim[2] = 0;
+        tim[3] = dtim_period;
+        tim[4] = 0;
+
+        if (dtim_len > 3)
+                skb_trim(skb, skb->len - (dtim_len - 3));
 
-                        /* add the dummy at the end */
-                        pos[0] = WLAN_EID_TIM;
-                        pos[1] = 3;
-                        pos[2] = 0;
-                        pos[3] = dtim_period;
-                        pos[4] = 0;
-                        return 0;
-                }
-                pos += 2 + pos[1];
-        }
         return 0;
 }
 
@@ -384,6 +397,9 @@ static void p54_bss_info_changed(struct ieee80211_hw *dev,
                         priv->wakeup_timer = info->beacon_int *
                                              info->dtim_period * 5;
                         p54_setup_mac(priv);
+                } else {
+                        priv->wakeup_timer = 500;
+                        priv->aid = 0;
                 }
         }
 
@@ -517,6 +533,9 @@ struct ieee80211_hw *p54_init_common(size_t priv_data_len)
         skb_queue_head_init(&priv->tx_pending);
         dev->flags = IEEE80211_HW_RX_INCLUDES_FCS |
                      IEEE80211_HW_SIGNAL_DBM |
+                     IEEE80211_HW_SUPPORTS_PS |
+                     IEEE80211_HW_PS_NULLFUNC_STACK |
+                     IEEE80211_HW_BEACON_FILTER |
                      IEEE80211_HW_NOISE_DBM;
 
         dev->wiphy->interface_modes = BIT(NL80211_IFTYPE_STATION) |
diff --git a/drivers/net/wireless/p54/p54.h b/drivers/net/wireless/p54/p54.h
index 19d085c73d7d..6772ed505d4d 100644
--- a/drivers/net/wireless/p54/p54.h
+++ b/drivers/net/wireless/p54/p54.h
@@ -208,6 +208,7 @@ struct p54_common {
         u32 tsf_low32, tsf_high32;
         u32 basic_rate_mask;
         u16 aid;
+        bool powersave_override;
         __le32 beacon_req_id;
 
         /* cryptographic engine information */
diff --git a/drivers/net/wireless/p54/txrx.c b/drivers/net/wireless/p54/txrx.c
index 6426d2cae6de..01eadb1683fa 100644
--- a/drivers/net/wireless/p54/txrx.c
+++ b/drivers/net/wireless/p54/txrx.c
@@ -288,6 +288,45 @@ static int p54_rssi_to_dbm(struct p54_common *priv, int rssi)
                          priv->rssical_db[band].add) / 4;
 }
 
+/*
+ * Even if the firmware is capable of dealing with incoming traffic,
+ * while dozing, we have to prepared in case mac80211 uses PS-POLL
+ * to retrieve outstanding frames from our AP.
+ * (see comment in net/mac80211/mlme.c @ line 1993)
+ */
+static void p54_pspoll_workaround(struct p54_common *priv, struct sk_buff *skb)
+{
+        struct ieee80211_hdr *hdr = (void *) skb->data;
+        struct ieee80211_tim_ie *tim_ie;
+        u8 *tim;
+        u8 tim_len;
+        bool new_psm;
+
+        /* only beacons have a TIM IE */
+        if (!ieee80211_is_beacon(hdr->frame_control))
+                return;
+
+        if (!priv->aid)
+                return;
+
+        /* only consider beacons from the associated BSSID */
+        if (compare_ether_addr(hdr->addr3, priv->bssid))
+                return;
+
+        tim = p54_find_ie(skb, WLAN_EID_TIM);
+        if (!tim)
+                return;
+
+        tim_len = tim[1];
+        tim_ie = (struct ieee80211_tim_ie *) &tim[2];
+
+        new_psm = ieee80211_check_tim(tim_ie, tim_len, priv->aid);
+        if (new_psm != priv->powersave_override) {
+                priv->powersave_override = new_psm;
+                p54_set_ps(priv);
+        }
+}
+
 static int p54_rx_data(struct p54_common *priv, struct sk_buff *skb)
 {
         struct p54_rx_data *hdr = (struct p54_rx_data *) skb->data;
@@ -340,6 +379,9 @@ static int p54_rx_data(struct p54_common *priv, struct sk_buff *skb)
 
         skb_pull(skb, header_len);
         skb_trim(skb, le16_to_cpu(hdr->len));
+        if (unlikely(priv->hw->conf.flags & IEEE80211_CONF_PS))
+                p54_pspoll_workaround(priv, skb);
+
         ieee80211_rx_irqsafe(priv->hw, skb);
 
         queue_delayed_work(priv->hw->workqueue, &priv->work,