ath10k: htt: High latency RX support

Special HTT RX handling for high latency interfaces.

Since no DMA physical addresses are used in the RX ring
config message (this is not supported by the high latency
devices), no RX ring is allocated.
All RX skb's are allocated by the driver and passed directly
to mac80211 in the HTT RX indication handler.

A nice side effect of this is that no huge buffer will be
allocated with dma_alloc_coherent. On embedded systems with
limited memory resources, the allocation of the RX ring is
prone to fail.

Some tweaks made to "make it work":

Removal of protected bit in 802.11 header frame control field.
The chipset seems to do hw decryption but the frame_control
protected bit is still set.

This is necessary for mac80211 not to drop the frame.

Signed-off-by: Erik Stromdahl <erik.stromdahl@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

1 files changed, 125 insertions, 3 deletions

diff --git a/drivers/net/wireless/ath/ath10k/htt_rx.c b/drivers/net/wireless/ath/ath10k/htt_rx.c
index 231e5914e16a..769da2d1f780 100644
--- a/drivers/net/wireless/ath/ath10k/htt_rx.c
+++ b/drivers/net/wireless/ath/ath10k/htt_rx.c
@@ -265,6 +265,9 @@ int ath10k_htt_rx_ring_refill(struct ath10k *ar)
 	struct ath10k_htt *htt = &ar->htt;
 	int ret;
 
+	if (ar->dev_type == ATH10K_DEV_TYPE_HL)
+		return 0;
+
 	spin_lock_bh(&htt->rx_ring.lock);
 	ret = ath10k_htt_rx_ring_fill_n(htt, (htt->rx_ring.fill_level -
 					      htt->rx_ring.fill_cnt));
@@ -279,6 +282,9 @@ int ath10k_htt_rx_ring_refill(struct ath10k *ar)
 
 void ath10k_htt_rx_free(struct ath10k_htt *htt)
 {
+	if (htt->ar->dev_type == ATH10K_DEV_TYPE_HL)
+		return;
+
 	del_timer_sync(&htt->rx_ring.refill_retry_timer);
 
 	skb_queue_purge(&htt->rx_msdus_q);
@@ -570,6 +576,9 @@ int ath10k_htt_rx_alloc(struct ath10k_htt *htt)
 	size_t size;
 	struct timer_list *timer = &htt->rx_ring.refill_retry_timer;
 
+	if (ar->dev_type == ATH10K_DEV_TYPE_HL)
+		return 0;
+
 	htt->rx_confused = false;
 
 	/* XXX: The fill level could be changed during runtime in response to
@@ -1846,8 +1855,116 @@ static int ath10k_htt_rx_handle_amsdu(struct ath10k_htt *htt)
 	return 0;
 }
 
-static void ath10k_htt_rx_proc_rx_ind(struct ath10k_htt *htt,
-				      struct htt_rx_indication *rx)
+static bool ath10k_htt_rx_proc_rx_ind_hl(struct ath10k_htt *htt,
+					 struct htt_rx_indication_hl *rx,
+					 struct sk_buff *skb)
+{
+	struct ath10k *ar = htt->ar;
+	struct ath10k_peer *peer;
+	struct htt_rx_indication_mpdu_range *mpdu_ranges;
+	struct fw_rx_desc_hl *fw_desc;
+	struct ieee80211_hdr *hdr;
+	struct ieee80211_rx_status *rx_status;
+	u16 peer_id;
+	u8 rx_desc_len;
+	int num_mpdu_ranges;
+	size_t tot_hdr_len;
+	struct ieee80211_channel *ch;
+
+	peer_id = __le16_to_cpu(rx->hdr.peer_id);
+
+	spin_lock_bh(&ar->data_lock);
+	peer = ath10k_peer_find_by_id(ar, peer_id);
+	spin_unlock_bh(&ar->data_lock);
+	if (!peer)
+		ath10k_warn(ar, "Got RX ind from invalid peer: %u\n", peer_id);
+
+	num_mpdu_ranges = MS(__le32_to_cpu(rx->hdr.info1),
+			     HTT_RX_INDICATION_INFO1_NUM_MPDU_RANGES);
+	mpdu_ranges = htt_rx_ind_get_mpdu_ranges_hl(rx);
+	fw_desc = &rx->fw_desc;
+	rx_desc_len = fw_desc->len;
+
+	/* I have not yet seen any case where num_mpdu_ranges > 1.
+	 * qcacld does not seem handle that case either, so we introduce the
+	 * same limitiation here as well.
+	 */
+	if (num_mpdu_ranges > 1)
+		ath10k_warn(ar,
+			    "Unsupported number of MPDU ranges: %d, ignoring all but the first\n",
+			    num_mpdu_ranges);
+
+	if (mpdu_ranges->mpdu_range_status !=
+	    HTT_RX_IND_MPDU_STATUS_OK) {
+		ath10k_warn(ar, "MPDU range status: %d\n",
+			    mpdu_ranges->mpdu_range_status);
+		goto err;
+	}
+
+	/* Strip off all headers before the MAC header before delivery to
+	 * mac80211
+	 */
+	tot_hdr_len = sizeof(struct htt_resp_hdr) + sizeof(rx->hdr) +
+		      sizeof(rx->ppdu) + sizeof(rx->prefix) +
+		      sizeof(rx->fw_desc) +
+		      sizeof(*mpdu_ranges) * num_mpdu_ranges + rx_desc_len;
+	skb_pull(skb, tot_hdr_len);
+
+	hdr = (struct ieee80211_hdr *)skb->data;
+	rx_status = IEEE80211_SKB_RXCB(skb);
+	rx_status->chains |= BIT(0);
+	rx_status->signal = ATH10K_DEFAULT_NOISE_FLOOR +
+			    rx->ppdu.combined_rssi;
+	rx_status->flag &= ~RX_FLAG_NO_SIGNAL_VAL;
+
+	spin_lock_bh(&ar->data_lock);
+	ch = ar->scan_channel;
+	if (!ch)
+		ch = ar->rx_channel;
+	if (!ch)
+		ch = ath10k_htt_rx_h_any_channel(ar);
+	if (!ch)
+		ch = ar->tgt_oper_chan;
+	spin_unlock_bh(&ar->data_lock);
+
+	if (ch) {
+		rx_status->band = ch->band;
+		rx_status->freq = ch->center_freq;
+	}
+	if (rx->fw_desc.flags & FW_RX_DESC_FLAGS_LAST_MSDU)
+		rx_status->flag &= ~RX_FLAG_AMSDU_MORE;
+	else
+		rx_status->flag |= RX_FLAG_AMSDU_MORE;
+
+	/* Not entirely sure about this, but all frames from the chipset has
+	 * the protected flag set even though they have already been decrypted.
+	 * Unmasking this flag is necessary in order for mac80211 not to drop
+	 * the frame.
+	 * TODO: Verify this is always the case or find out a way to check
+	 * if there has been hw decryption.
+	 */
+	if (ieee80211_has_protected(hdr->frame_control)) {
+		hdr->frame_control &= ~__cpu_to_le16(IEEE80211_FCTL_PROTECTED);
+		rx_status->flag |= RX_FLAG_DECRYPTED |
+				   RX_FLAG_IV_STRIPPED |
+				   RX_FLAG_MMIC_STRIPPED;
+	}
+
+	ieee80211_rx_ni(ar->hw, skb);
+
+	/* We have delivered the skb to the upper layers (mac80211) so we
+	 * must not free it.
+	 */
+	return false;
+err:
+	/* Tell the caller that it must free the skb since we have not
+	 * consumed it
+	 */
+	return true;
+}
+
+static void ath10k_htt_rx_proc_rx_ind_ll(struct ath10k_htt *htt,
+					 struct htt_rx_indication *rx)
 {
 	struct ath10k *ar = htt->ar;
 	struct htt_rx_indication_mpdu_range *mpdu_ranges;
@@ -2829,7 +2946,12 @@ bool ath10k_htt_t2h_msg_handler(struct ath10k *ar, struct sk_buff *skb)
 		break;
 	}
 	case HTT_T2H_MSG_TYPE_RX_IND:
-		ath10k_htt_rx_proc_rx_ind(htt, &resp->rx_ind);
+		if (ar->dev_type == ATH10K_DEV_TYPE_HL)
+			return ath10k_htt_rx_proc_rx_ind_hl(htt,
+							    &resp->rx_ind_hl,
+							    skb);
+		else
+			ath10k_htt_rx_proc_rx_ind_ll(htt, &resp->rx_ind);
 		break;
 	case HTT_T2H_MSG_TYPE_PEER_MAP: {
 		struct htt_peer_map_event ev = {