iwlwifi: pcie: support frag SKBs

Allow frag SKBs in PCIe and advertise the maximum number of frags
to the opmode. As a fallback. linearize the SKB if it exceeds the
maximum number of fragments. This allows using the hardware better
(filling more TBs) and should improve performance when used by the
opmode.

Also adjust tracing to be able to deal with this.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

3 files changed, 66 insertions, 12 deletions

diff --git a/drivers/net/wireless/iwlwifi/pcie/internal.h b/drivers/net/wireless/iwlwifi/pcie/internal.h
index 17f65dc89472..feb2f7e81134 100644
--- a/drivers/net/wireless/iwlwifi/pcie/internal.h
+++ b/drivers/net/wireless/iwlwifi/pcie/internal.h
@@ -44,6 +44,12 @@
 #include "iwl-io.h"
 #include "iwl-op-mode.h"
 
+/* We need 2 entries for the TX command and header, and another one might
+ * be needed for potential data in the SKB's head. The remaining ones can
+ * be used for frags.
+ */
+#define IWL_PCIE_MAX_FRAGS (IWL_NUM_OF_TBS - 3)
+
 /*
  * RX related structures and functions
  */
diff --git a/drivers/net/wireless/iwlwifi/pcie/trans.c b/drivers/net/wireless/iwlwifi/pcie/trans.c
index 9ebdd8009717..fb55810f5aae 100644
--- a/drivers/net/wireless/iwlwifi/pcie/trans.c
+++ b/drivers/net/wireless/iwlwifi/pcie/trans.c
@@ -2627,6 +2627,8 @@ struct iwl_trans *iwl_trans_pcie_alloc(struct pci_dev *pdev,
 	if (!trans)
 		return ERR_PTR(-ENOMEM);
 
+	trans->max_skb_frags = IWL_PCIE_MAX_FRAGS;
+
 	trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
 
 	trans_pcie->trans = trans;
diff --git a/drivers/net/wireless/iwlwifi/pcie/tx.c b/drivers/net/wireless/iwlwifi/pcie/tx.c
index 601eee1ad60b..b7d1268bf969 100644
--- a/drivers/net/wireless/iwlwifi/pcie/tx.c
+++ b/drivers/net/wireless/iwlwifi/pcie/tx.c
@@ -388,11 +388,18 @@ static void iwl_pcie_tfd_unmap(struct iwl_trans *trans,
 
 	/* first TB is never freed - it's the scratchbuf data */
 
-	for (i = 1; i < num_tbs; i++)
-		dma_unmap_single(trans->dev, iwl_pcie_tfd_tb_get_addr(tfd, i),
-				 iwl_pcie_tfd_tb_get_len(tfd, i),
-				 DMA_TO_DEVICE);
-
+	for (i = 1; i < num_tbs; i++) {
+		if (meta->flags & BIT(i + CMD_TB_BITMAP_POS))
+			dma_unmap_page(trans->dev,
+				       iwl_pcie_tfd_tb_get_addr(tfd, i),
+				       iwl_pcie_tfd_tb_get_len(tfd, i),
+				       DMA_TO_DEVICE);
+		else
+			dma_unmap_single(trans->dev,
+					 iwl_pcie_tfd_tb_get_addr(tfd, i),
+					 iwl_pcie_tfd_tb_get_len(tfd, i),
+					 DMA_TO_DEVICE);
+	}
 	tfd->num_tbs = 0;
 }
 
@@ -468,7 +475,7 @@ static int iwl_pcie_txq_build_tfd(struct iwl_trans *trans, struct iwl_txq *txq,
 
 	iwl_pcie_tfd_set_tb(tfd, num_tbs, addr, len);
 
-	return 0;
+	return num_tbs;
 }
 
 static int iwl_pcie_txq_alloc(struct iwl_trans *trans,
@@ -1546,6 +1553,8 @@ static int iwl_pcie_enqueue_hcmd(struct iwl_trans *trans,
 		iwl_pcie_txq_build_tfd(trans, txq, phys_addr, cmdlen[i], false);
 	}
 
+	BUILD_BUG_ON(IWL_NUM_OF_TBS + CMD_TB_BITMAP_POS >
+		     sizeof(out_meta->flags) * BITS_PER_BYTE);
 	out_meta->flags = cmd->flags;
 	if (WARN_ON_ONCE(txq->entries[idx].free_buf))
 		kzfree(txq->entries[idx].free_buf);
@@ -1789,7 +1798,7 @@ int iwl_trans_pcie_tx(struct iwl_trans *trans, struct sk_buff *skb,
 		      struct iwl_device_cmd *dev_cmd, int txq_id)
 {
 	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
-	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
+	struct ieee80211_hdr *hdr;
 	struct iwl_tx_cmd *tx_cmd = (struct iwl_tx_cmd *)dev_cmd->payload;
 	struct iwl_cmd_meta *out_meta;
 	struct iwl_txq *txq;
@@ -1798,9 +1807,10 @@ int iwl_trans_pcie_tx(struct iwl_trans *trans, struct sk_buff *skb,
 	void *tb1_addr;
 	u16 len, tb1_len, tb2_len;
 	bool wait_write_ptr;
-	__le16 fc = hdr->frame_control;
-	u8 hdr_len = ieee80211_hdrlen(fc);
+	__le16 fc;
+	u8 hdr_len;
 	u16 wifi_seq;
+	int i;
 
 	txq = &trans_pcie->txq[txq_id];
 	q = &txq->q;
@@ -1809,6 +1819,18 @@ int iwl_trans_pcie_tx(struct iwl_trans *trans, struct sk_buff *skb,
 		      "TX on unused queue %d\n", txq_id))
 		return -EINVAL;
 
+	if (skb_is_nonlinear(skb) &&
+	    skb_shinfo(skb)->nr_frags > IWL_PCIE_MAX_FRAGS &&
+	    __skb_linearize(skb))
+		return -ENOMEM;
+
+	/* mac80211 always puts the full header into the SKB's head,
+	 * so there's no need to check if it's readable there
+	 */
+	hdr = (struct ieee80211_hdr *)skb->data;
+	fc = hdr->frame_control;
+	hdr_len = ieee80211_hdrlen(fc);
+
 	spin_lock(&txq->lock);
 
 	/* In AGG mode, the index in the ring must correspond to the WiFi
@@ -1839,6 +1861,7 @@ int iwl_trans_pcie_tx(struct iwl_trans *trans, struct sk_buff *skb,
 
 	/* Set up first empty entry in queue's array of Tx/cmd buffers */
 	out_meta = &txq->entries[q->write_ptr].meta;
+	out_meta->flags = 0;
 
 	/*
 	 * The second TB (tb1) points to the remainder of the TX command
@@ -1872,9 +1895,9 @@ int iwl_trans_pcie_tx(struct iwl_trans *trans, struct sk_buff *skb,
 
 	/*
 	 * Set up TFD's third entry to point directly to remainder
-	 * of skb, if any (802.11 null frames have no payload).
+	 * of skb's head, if any
 	 */
-	tb2_len = skb->len - hdr_len;
+	tb2_len = skb_headlen(skb) - hdr_len;
 	if (tb2_len > 0) {
 		dma_addr_t tb2_phys = dma_map_single(trans->dev,
 						     skb->data + hdr_len,
@@ -1887,6 +1910,29 @@ int iwl_trans_pcie_tx(struct iwl_trans *trans, struct sk_buff *skb,
 		iwl_pcie_txq_build_tfd(trans, txq, tb2_phys, tb2_len, false);
 	}
 
+	/* set up the remaining entries to point to the data */
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+		dma_addr_t tb_phys;
+		int tb_idx;
+
+		if (!skb_frag_size(frag))
+			continue;
+
+		tb_phys = skb_frag_dma_map(trans->dev, frag, 0,
+					   skb_frag_size(frag), DMA_TO_DEVICE);
+
+		if (unlikely(dma_mapping_error(trans->dev, tb_phys))) {
+			iwl_pcie_tfd_unmap(trans, out_meta,
+					   &txq->tfds[q->write_ptr]);
+			goto out_err;
+		}
+		tb_idx = iwl_pcie_txq_build_tfd(trans, txq, tb_phys,
+						skb_frag_size(frag), false);
+
+		out_meta->flags |= BIT(tb_idx + CMD_TB_BITMAP_POS);
+	}
+
 	/* Set up entry for this TFD in Tx byte-count array */
 	iwl_pcie_txq_update_byte_cnt_tbl(trans, txq, le16_to_cpu(tx_cmd->len));
 
@@ -1896,7 +1942,7 @@ int iwl_trans_pcie_tx(struct iwl_trans *trans, struct sk_buff *skb,
 			     &dev_cmd->hdr, IWL_HCMD_SCRATCHBUF_SIZE + tb1_len,
 			     skb->data + hdr_len, tb2_len);
 	trace_iwlwifi_dev_tx_data(trans->dev, skb,
-				  skb->data + hdr_len, tb2_len);
+				  hdr_len, skb->len - hdr_len);
 
 	wait_write_ptr = ieee80211_has_morefrags(fc);