net/mlx5: Ethernet Datapath files

en_[rt]x.c contains the data path related code specific to tx or rx.
en_txrx.c contains data path code which is common for both the rx and
tx, this is mainly napi related code.

Below are the objects that are being used by the hardware and the driver
in the data path:

Channel - one channel per IRQ. Every channel object contains:
  RQ  - describes the rx queue
  TIR - One TIR (Transport Interface Receive) object per flow type. TIR
        contains attributes for a type of rx flow (e.g IPv4, IPv6 etc).
        A flow is defined in the Flow Table.
        Currently TIR describes the RSS hash parameters if exists and LRO
        attributes.
  SQ  - describes the a tx queue. There is one SQ (Send Queue) per
        TC (traffic class).
  TIS - There is one TIS (Transport Interface Send) per TC.  It
        describes the TC and may later be extended to describe more
	transport properties.

Both RQ and SQ inherit from the object WQ (work queue). This common code
to describe the layout of CQE's WQE's in memory is in the files wq.[cj]

For every channel there is one NAPI context that is used for RX and
for TX.

Driver is using netdev_alloc_skb() to allocate skb's.

Signed-off-by: Amir Vadai <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: amirv

drivers/net/ethernet/mellanox/mlx5/core/en_rx.c

@@ -0,0 +1,249 @@
+/*
+ * Copyright (c) 2015, Mellanox Technologies. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      - Redistributions of source code must retain the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer.
+ *
+ *      - Redistributions in binary form must reproduce the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer in the documentation and/or other materials
+ *        provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/tcp.h>
+#include "en.h"
+
+static inline int mlx5e_alloc_rx_wqe(struct mlx5e_rq *rq,
+				     struct mlx5e_rx_wqe *wqe, u16 ix)
+{
+	struct sk_buff *skb;
+	dma_addr_t dma_addr;
+
+	skb = netdev_alloc_skb(rq->netdev, rq->wqe_sz);
+	if (unlikely(!skb))
+		return -ENOMEM;
+
+	skb_reserve(skb, MLX5E_NET_IP_ALIGN);
+
+	dma_addr = dma_map_single(rq->pdev,
+				  /* hw start padding */
+				  skb->data - MLX5E_NET_IP_ALIGN,
+				  /* hw   end padding */
+				  rq->wqe_sz,
+				  DMA_FROM_DEVICE);
+
+	if (unlikely(dma_mapping_error(rq->pdev, dma_addr)))
+		goto err_free_skb;
+
+	*((dma_addr_t *)skb->cb) = dma_addr;
+	wqe->data.addr = cpu_to_be64(dma_addr + MLX5E_NET_IP_ALIGN);
+
+	rq->skb[ix] = skb;
+
+	return 0;
+
+err_free_skb:
+	dev_kfree_skb(skb);
+
+	return -ENOMEM;
+}
+
+bool mlx5e_post_rx_wqes(struct mlx5e_rq *rq)
+{
+	struct mlx5_wq_ll *wq = &rq->wq;
+
+	if (unlikely(!test_bit(MLX5E_RQ_STATE_POST_WQES_ENABLE, &rq->state)))
+		return false;
+
+	while (!mlx5_wq_ll_is_full(wq)) {
+		struct mlx5e_rx_wqe *wqe = mlx5_wq_ll_get_wqe(wq, wq->head);
+
+		if (unlikely(mlx5e_alloc_rx_wqe(rq, wqe, wq->head)))
+			break;
+
+		mlx5_wq_ll_push(wq, be16_to_cpu(wqe->next.next_wqe_index));
+	}
+
+	/* ensure wqes are visible to device before updating doorbell record */
+	dma_wmb();
+
+	mlx5_wq_ll_update_db_record(wq);
+
+	return !mlx5_wq_ll_is_full(wq);
+}
+
+static void mlx5e_lro_update_hdr(struct sk_buff *skb, struct mlx5_cqe64 *cqe)
+{
+	struct ethhdr	*eth	= (struct ethhdr *)(skb->data);
+	struct iphdr	*ipv4	= (struct iphdr *)(skb->data + ETH_HLEN);
+	struct ipv6hdr	*ipv6	= (struct ipv6hdr *)(skb->data + ETH_HLEN);
+	struct tcphdr	*tcp;
+
+	u8 l4_hdr_type = get_cqe_l4_hdr_type(cqe);
+	int tcp_ack = ((CQE_L4_HDR_TYPE_TCP_ACK_NO_DATA  == l4_hdr_type) ||
+		       (CQE_L4_HDR_TYPE_TCP_ACK_AND_DATA == l4_hdr_type));
+
+	u16 tot_len = be32_to_cpu(cqe->byte_cnt) - ETH_HLEN;
+
+	if (eth->h_proto == htons(ETH_P_IP)) {
+		tcp = (struct tcphdr *)(skb->data + ETH_HLEN +
+					sizeof(struct iphdr));
+		ipv6 = NULL;
+	} else {
+		tcp = (struct tcphdr *)(skb->data + ETH_HLEN +
+					sizeof(struct ipv6hdr));
+		ipv4 = NULL;
+	}
+
+	if (get_cqe_lro_tcppsh(cqe))
+		tcp->psh                = 1;
+
+	if (tcp_ack) {
+		tcp->ack                = 1;
+		tcp->ack_seq            = cqe->lro_ack_seq_num;
+		tcp->window             = cqe->lro_tcp_win;
+	}
+
+	if (ipv4) {
+		ipv4->ttl               = cqe->lro_min_ttl;
+		ipv4->tot_len           = cpu_to_be16(tot_len);
+		ipv4->check             = 0;
+		ipv4->check             = ip_fast_csum((unsigned char *)ipv4,
+						       ipv4->ihl);
+	} else {
+		ipv6->hop_limit         = cqe->lro_min_ttl;
+		ipv6->payload_len       = cpu_to_be16(tot_len -
+						      sizeof(struct ipv6hdr));
+	}
+}
+
+static inline void mlx5e_skb_set_hash(struct mlx5_cqe64 *cqe,
+				      struct sk_buff *skb)
+{
+	u8 cht = cqe->rss_hash_type;
+	int ht = (cht & CQE_RSS_HTYPE_L4) ? PKT_HASH_TYPE_L4 :
+		 (cht & CQE_RSS_HTYPE_IP) ? PKT_HASH_TYPE_L3 :
+					    PKT_HASH_TYPE_NONE;
+	skb_set_hash(skb, be32_to_cpu(cqe->rss_hash_result), ht);
+}
+
+static inline void mlx5e_build_rx_skb(struct mlx5_cqe64 *cqe,
+				      struct mlx5e_rq *rq,
+				      struct sk_buff *skb)
+{
+	struct net_device *netdev = rq->netdev;
+	u32 cqe_bcnt = be32_to_cpu(cqe->byte_cnt);
+	int lro_num_seg;
+
+	skb_put(skb, cqe_bcnt);
+
+	lro_num_seg = be32_to_cpu(cqe->srqn) >> 24;
+	if (lro_num_seg > 1) {
+		mlx5e_lro_update_hdr(skb, cqe);
+		skb_shinfo(skb)->gso_size = MLX5E_PARAMS_DEFAULT_LRO_WQE_SZ;
+		rq->stats.lro_packets++;
+		rq->stats.lro_bytes += cqe_bcnt;
+	}
+
+	if (likely(netdev->features & NETIF_F_RXCSUM) &&
+	    (cqe->hds_ip_ext & CQE_L2_OK) &&
+	    (cqe->hds_ip_ext & CQE_L3_OK) &&
+	    (cqe->hds_ip_ext & CQE_L4_OK)) {
+		skb->ip_summed = CHECKSUM_UNNECESSARY;
+	} else {
+		skb->ip_summed = CHECKSUM_NONE;
+		rq->stats.csum_none++;
+	}
+
+	skb->protocol = eth_type_trans(skb, netdev);
+
+	skb_record_rx_queue(skb, rq->ix);
+
+	if (likely(netdev->features & NETIF_F_RXHASH))
+		mlx5e_skb_set_hash(cqe, skb);
+
+	if (cqe_has_vlan(cqe))
+		__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),
+				       be16_to_cpu(cqe->vlan_info));
+}
+
+bool mlx5e_poll_rx_cq(struct mlx5e_cq *cq, int budget)
+{
+	struct mlx5e_rq *rq = cq->sqrq;
+	int i;
+
+	/* avoid accessing cq (dma coherent memory) if not needed */
+	if (!test_and_clear_bit(MLX5E_CQ_HAS_CQES, &cq->flags))
+		return false;
+
+	for (i = 0; i < budget; i++) {
+		struct mlx5e_rx_wqe *wqe;
+		struct mlx5_cqe64 *cqe;
+		struct sk_buff *skb;
+		__be16 wqe_counter_be;
+		u16 wqe_counter;
+
+		cqe = mlx5e_get_cqe(cq);
+		if (!cqe)
+			break;
+
+		wqe_counter_be = cqe->wqe_counter;
+		wqe_counter    = be16_to_cpu(wqe_counter_be);
+		wqe            = mlx5_wq_ll_get_wqe(&rq->wq, wqe_counter);
+		skb            = rq->skb[wqe_counter];
+		rq->skb[wqe_counter] = NULL;
+
+		dma_unmap_single(rq->pdev,
+				 *((dma_addr_t *)skb->cb),
+				 skb_end_offset(skb),
+				 DMA_FROM_DEVICE);
+
+		if (unlikely((cqe->op_own >> 4) != MLX5_CQE_RESP_SEND)) {
+			rq->stats.wqe_err++;
+			dev_kfree_skb(skb);
+			goto wq_ll_pop;
+		}
+
+		mlx5e_build_rx_skb(cqe, rq, skb);
+		rq->stats.packets++;
+		napi_gro_receive(cq->napi, skb);
+
+wq_ll_pop:
+		mlx5_wq_ll_pop(&rq->wq, wqe_counter_be,
+			       &wqe->next.next_wqe_index);
+	}
+
+	mlx5_cqwq_update_db_record(&cq->wq);
+
+	/* ensure cq space is freed before enabling more cqes */
+	wmb();
+
+	if (i == budget) {
+		set_bit(MLX5E_CQ_HAS_CQES, &cq->flags);
+		return true;
+	}
+
+	return false;
+}