dpaa2-eth: add support for software TSO

This patch adds support for driver level TSO in the enetc driver using
the TSO API.

There is not much to say about this specific implementation. We are
using the usual tso_build_hdr(), tso_build_data() to create each data
segment, we create an array of S/G FDs where the first S/G entry is
referencing the header data and the remaining ones the data portion.

For the S/G Table buffer we use the same cache of buffers used on the
other non-GSO cases - dpaa2_eth_sgt_get() and dpaa2_eth_sgt_recycle().

We cannot keep a DMA coherent buffer for all the TSO headers because the
DPAA2 architecture does not work in a ring based fashion so we just
allocate a buffer each time.

Even with these limitations we get the following improvement in TCP
termination on the LX2160A SoC, on a single A72 core running at 2.2GHz.

before: 6.38Gbit/s
after:  8.48Gbit/s

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
index 64e4aaebdcb2..b79831cd1a94 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
@@ -122,6 +122,7 @@ enum dpaa2_eth_swa_type {
 	DPAA2_ETH_SWA_SINGLE,
 	DPAA2_ETH_SWA_SG,
 	DPAA2_ETH_SWA_XDP,
+	DPAA2_ETH_SWA_SW_TSO,
 };
 
 /* Must keep this struct smaller than DPAA2_ETH_SWA_SIZE */
@@ -142,6 +143,12 @@ struct dpaa2_eth_swa {
 			int dma_size;
 			struct xdp_frame *xdpf;
 		} xdp;
+		struct {
+			struct sk_buff *skb;
+			int num_sg;
+			int sgt_size;
+			int is_last_fd;
+		} tso;
 	};
 };
 
@@ -354,6 +361,8 @@ struct dpaa2_eth_drv_stats {
 	__u64	tx_conf_bytes;
 	__u64	tx_sg_frames;
 	__u64	tx_sg_bytes;
+	__u64	tx_tso_frames;
+	__u64	tx_tso_bytes;
 	__u64	rx_sg_frames;
 	__u64	rx_sg_bytes;
 	/* Linear skbs sent as a S/G FD due to insufficient headroom */