Implement TSO for 82550/82551 controllers.

 o Configure controller to use dynamic TBD as TSO requires that
   operation mode.
 o Add a dummy TBD to tx_cb_u as TSO can access one more TBD in TSO
   operation.
 o Increase a DMA segment size to 4096 to hold a full IP segment
   with link layer header.
 o Unlike other TSO capable controllers, 82550/82551 does not
   modify the first IP packet in TSO operation so driver should
   create an IP packet with proper header. Subsequent IP packets
   are generated from the header information in the first IP packet
   header. Likewise pseudo checksum also should be computed by
   driver for the first packet.
 o TSO requires one more TBD to hold total TCP payload. To make
   code simple for TSO/non-TSO case, increase the index of the
   first available TBD array.
 o Remove KASSERT that checks the size of a DMA segment should be
   less than or equal to MCLBYTES as it's no longer valid in TSO.
 o Tx threshold and number of TBDs field is used to store MSS in
   TSO. So don't set the Tx threshold in TSO case.

3 files changed, 118 insertions, 14 deletions

diff --git a/sys/dev/fxp/if_fxp.c b/sys/dev/fxp/if_fxp.c
index 05632fd..156dd03 100644
--- a/sys/dev/fxp/if_fxp.c
+++ b/sys/dev/fxp/if_fxp.c
@@ -619,11 +619,15 @@ fxp_attach(device_t dev)
 	 * Allocate DMA tags and DMA safe memory.
 	 */
 	sc->maxtxseg = FXP_NTXSEG;
-	if (sc->flags & FXP_FLAG_EXT_RFA)
+	sc->maxsegsize = MCLBYTES;
+	if (sc->flags & FXP_FLAG_EXT_RFA) {
 		sc->maxtxseg--;
+		sc->maxsegsize = FXP_TSO_SEGSIZE;
+	}
 	error = bus_dma_tag_create(bus_get_dma_tag(dev), 2, 0,
 	    BUS_SPACE_MAXADDR_32BIT, BUS_SPACE_MAXADDR, NULL, NULL,
-	    MCLBYTES * sc->maxtxseg, sc->maxtxseg, MCLBYTES, 0,
+	    sc->maxsegsize * sc->maxtxseg + sizeof(struct ether_vlan_header),
+	    sc->maxtxseg, sc->maxsegsize, 0,
 	    busdma_lock_mutex, &Giant, &sc->fxp_mtag);
 	if (error) {
 		device_printf(dev, "could not allocate dma tag\n");
@@ -780,11 +784,11 @@ fxp_attach(device_t dev)
 
 	ifp->if_capabilities = ifp->if_capenable = 0;
 
-	/* Enable checksum offload for 82550 or better chips */
+	/* Enable checksum offload/TSO for 82550 or better chips */
 	if (sc->flags & FXP_FLAG_EXT_RFA) {
-		ifp->if_hwassist = FXP_CSUM_FEATURES;
-		ifp->if_capabilities |= IFCAP_HWCSUM;
-		ifp->if_capenable |= IFCAP_HWCSUM;
+		ifp->if_hwassist = FXP_CSUM_FEATURES | CSUM_TSO;
+		ifp->if_capabilities |= IFCAP_HWCSUM | IFCAP_TSO4;
+		ifp->if_capenable |= IFCAP_HWCSUM | IFCAP_TSO4;
 	}
 
 	if (sc->flags & FXP_FLAG_82559_RXCSUM) {
@@ -1275,12 +1279,15 @@ fxp_encap(struct fxp_softc *sc, struct mbuf **m_head)
 	struct mbuf *m;
 	struct fxp_tx *txp;
 	struct fxp_cb_tx *cbp;
+	struct tcphdr *tcp;
 	bus_dma_segment_t segs[FXP_NTXSEG];
-	int error, i, nseg;
+	int error, i, nseg, tcp_payload;
 
 	FXP_LOCK_ASSERT(sc, MA_OWNED);
 	ifp = sc->ifp;
 
+	tcp_payload = 0;
+	tcp = NULL;
 	/*
 	 * Get pointer to next available tx desc.
 	 */
@@ -1358,6 +1365,75 @@ fxp_encap(struct fxp_softc *sc, struct mbuf **m_head)
 #endif
 	}
 
+	if (m->m_pkthdr.csum_flags & CSUM_TSO) {
+		/*
+		 * 82550/82551 requires ethernet/IP/TCP headers must be
+		 * contained in the first active transmit buffer.
+		 */
+		struct ether_header *eh;
+		struct ip *ip;
+		uint32_t ip_off, poff;
+
+		if (M_WRITABLE(*m_head) == 0) {
+			/* Get a writable copy. */
+			m = m_dup(*m_head, M_DONTWAIT);
+			m_freem(*m_head);
+			if (m == NULL) {
+				*m_head = NULL;
+				return (ENOBUFS);
+			}
+			*m_head = m;
+		}
+		ip_off = sizeof(struct ether_header);
+		m = m_pullup(*m_head, ip_off);
+		if (m == NULL) {
+			*m_head = NULL;
+			return (ENOBUFS);
+		}
+		eh = mtod(m, struct ether_header *);
+		/* Check the existence of VLAN tag. */
+		if (eh->ether_type == htons(ETHERTYPE_VLAN)) {
+			ip_off = sizeof(struct ether_vlan_header);
+			m = m_pullup(m, ip_off);
+			if (m == NULL) {
+				*m_head = NULL;
+				return (ENOBUFS);
+			}
+		}
+		m = m_pullup(m, ip_off + sizeof(struct ip));
+		if (m == NULL) {
+			*m_head = NULL;
+			return (ENOBUFS);
+		}
+		ip = (struct ip *)(mtod(m, char *) + ip_off);
+		poff = ip_off + (ip->ip_hl << 2);
+		m = m_pullup(m, poff + sizeof(struct tcphdr));
+		if (m == NULL) {
+			*m_head = NULL;
+			return (ENOBUFS);
+		}
+		tcp = (struct tcphdr *)(mtod(m, char *) + poff);
+		m = m_pullup(m, poff + sizeof(struct tcphdr) + tcp->th_off);
+		if (m == NULL) {
+			*m_head = NULL;
+			return (ENOBUFS);
+		}
+
+		/*
+		 * Since 82550/82551 doesn't modify IP length and pseudo
+		 * checksum in the first frame driver should compute it.
+		 */
+		ip->ip_sum = 0;
+		ip->ip_len = htons(ifp->if_mtu);
+		tcp->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
+		    htons(IPPROTO_TCP + (tcp->th_off << 2) +
+		    m->m_pkthdr.tso_segsz));
+		/* Compute total TCP payload. */
+		tcp_payload = m->m_pkthdr.len - ip_off - (ip->ip_hl << 2);
+		tcp_payload -= tcp->th_off << 2;
+		*m_head = m;
+	}
+
 	error = bus_dmamap_load_mbuf_sg(sc->fxp_mtag, txp->tx_map, *m_head,
 	    segs, &nseg, 0);
 	if (error == EFBIG) {
@@ -1388,7 +1464,6 @@ fxp_encap(struct fxp_softc *sc, struct mbuf **m_head)
 
 	cbp = txp->tx_cb;
 	for (i = 0; i < nseg; i++) {
-		KASSERT(segs[i].ds_len <= MCLBYTES, ("segment size too large"));
 		/*
 		 * If this is an 82550/82551, then we're using extended
 		 * TxCBs _and_ we're using checksum offload. This means
@@ -1403,14 +1478,28 @@ fxp_encap(struct fxp_softc *sc, struct mbuf **m_head)
 		 * the chip is an 82550/82551 or not.
 		 */
 		if (sc->flags & FXP_FLAG_EXT_RFA) {
-			cbp->tbd[i + 1].tb_addr = htole32(segs[i].ds_addr);
-			cbp->tbd[i + 1].tb_size = htole32(segs[i].ds_len);
+			cbp->tbd[i + 2].tb_addr = htole32(segs[i].ds_addr);
+			cbp->tbd[i + 2].tb_size = htole32(segs[i].ds_len);
 		} else {
 			cbp->tbd[i].tb_addr = htole32(segs[i].ds_addr);
 			cbp->tbd[i].tb_size = htole32(segs[i].ds_len);
 		}
 	}
-	cbp->tbd_number = nseg;
+	if (sc->flags & FXP_FLAG_EXT_RFA) {
+		/* Configure dynamic TBD for 82550/82551. */
+		cbp->tbd_number = 0xFF;
+		cbp->tbd[nseg + 1].tb_size |= htole32(0x8000);
+	} else
+		cbp->tbd_number = nseg;
+	/* Configure TSO. */
+	if (m->m_pkthdr.csum_flags & CSUM_TSO) {
+		cbp->tbd[-1].tb_size = htole32(m->m_pkthdr.tso_segsz << 16);
+		cbp->tbd[1].tb_size = htole32(tcp_payload << 16);
+		cbp->ipcb_ip_schedule |= FXP_IPCB_LARGESEND_ENABLE |
+		    FXP_IPCB_IP_CHECKSUM_ENABLE |
+		    FXP_IPCB_TCP_PACKET |
+		    FXP_IPCB_TCPUDP_CHECKSUM_ENABLE;
+	}
 
 	txp->tx_mbuf = m;
 	txp->tx_cb->cb_status = 0;
@@ -1423,7 +1512,8 @@ fxp_encap(struct fxp_softc *sc, struct mbuf **m_head)
 		txp->tx_cb->cb_command =
 		    htole16(sc->tx_cmd | FXP_CB_COMMAND_SF |
 		    FXP_CB_COMMAND_S | FXP_CB_COMMAND_I);
-	txp->tx_cb->tx_threshold = tx_threshold;
+	if ((m->m_pkthdr.csum_flags & CSUM_TSO) == 0)
+		txp->tx_cb->tx_threshold = tx_threshold;
 
 	/*
 	 * Advance the end of list forward.
@@ -2097,7 +2187,7 @@ fxp_init_body(struct fxp_softc *sc)
 	cbp->disc_short_rx =	!prm;	/* discard short packets */
 	cbp->underrun_retry =	1;	/* retry mode (once) on DMA underrun */
 	cbp->two_frames =	0;	/* do not limit FIFO to 2 frames */
-	cbp->dyn_tbd =		0;	/* (no) dynamic TBD mode */
+	cbp->dyn_tbd =		sc->flags & FXP_FLAG_EXT_RFA ? 1 : 0;
 	cbp->ext_rfa =		sc->flags & FXP_FLAG_EXT_RFA ? 1 : 0;
 	cbp->mediatype =	sc->flags & FXP_FLAG_SERIAL_MEDIA ? 0 : 1;
 	cbp->csma_dis =		0;	/* (don't) disable link */
@@ -2589,6 +2679,14 @@ fxp_ioctl(struct ifnet *ifp, u_long command, caddr_t data)
 			if ((sc->flags & FXP_FLAG_82559_RXCSUM) != 0)
 				reinit++;
 		}
+		if ((mask & IFCAP_TSO4) != 0 &&
+		    (ifp->if_capabilities & IFCAP_TSO4) != 0) {
+			ifp->if_capenable ^= IFCAP_TSO4;
+			if ((ifp->if_capenable & IFCAP_TSO4) != 0)
+				ifp->if_hwassist |= CSUM_TSO;
+			else
+				ifp->if_hwassist &= ~CSUM_TSO;
+		}
 		if ((mask & IFCAP_VLAN_MTU) != 0 &&
 		    (ifp->if_capabilities & IFCAP_VLAN_MTU) != 0) {
 			ifp->if_capenable ^= IFCAP_VLAN_MTU;
diff --git a/sys/dev/fxp/if_fxpreg.h b/sys/dev/fxp/if_fxpreg.h
index 26edfbd..982d2f0 100644
--- a/sys/dev/fxp/if_fxpreg.h
+++ b/sys/dev/fxp/if_fxpreg.h
@@ -292,7 +292,7 @@ struct fxp_cb_tx {
 	 */
 	union {
 		struct fxp_ipcb ipcb;
-		struct fxp_tbd tbd[FXP_NTXSEG];
+		struct fxp_tbd tbd[FXP_NTXSEG + 1];
 	} tx_cb_u;
 };
 
diff --git a/sys/dev/fxp/if_fxpvar.h b/sys/dev/fxp/if_fxpvar.h
index fdaff2e..5926fdc 100644
--- a/sys/dev/fxp/if_fxpvar.h
+++ b/sys/dev/fxp/if_fxpvar.h
@@ -41,6 +41,11 @@
 #define	FXP_NTXCB_HIWAT	((FXP_NTXCB * 7) / 10)
 
 /*
+ * Maximum size of a DMA segment.
+ */
+#define	FXP_TSO_SEGSIZE	4096
+
+/*
  * Size of the TxCB list.
  */
 #define FXP_TXCB_SZ	(FXP_NTXCB * sizeof(struct fxp_cb_tx))
@@ -157,6 +162,7 @@ struct fxp_softc {
 	bus_dmamap_t spare_map;		/* spare DMA map */
 	struct fxp_desc_list fxp_desc;	/* descriptors management struct */
 	int maxtxseg;			/* maximum # of TX segments */
+	int maxsegsize;			/* maximum size of a TX segment */
 	int tx_queued;			/* # of active TxCB's */
 	int need_mcsetup;		/* multicast filter needs programming */
 	struct fxp_stats *fxp_stats;	/* Pointer to interface stats */