Add RX TCP/UDP checksum offload support.

ok naddy@ sthen@

1 files changed, 100 insertions, 2 deletions

diff --git a/sys/dev/ic/gem.c b/sys/dev/ic/gem.c
index f805cf78866..e365f105987 100644
--- a/sys/dev/ic/gem.c
+++ b/sys/dev/ic/gem.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: gem.c,v 1.97 2012/10/22 05:05:57 brad Exp $	*/
+/*	$OpenBSD: gem.c,v 1.98 2012/12/01 10:04:58 brad Exp $	*/
 /*	$NetBSD: gem.c,v 1.1 2001/09/16 00:11:43 eeh Exp $ */
 
 /*
@@ -56,7 +56,11 @@
 
 #ifdef INET
 #include <netinet/in.h>
+#include <netinet/in_systm.h>
+#include <netinet/ip.h>
 #include <netinet/if_ether.h>
+#include <netinet/tcp.h>
+#include <netinet/udp.h>
 #endif
 
 #if NBPFILTER > 0
@@ -116,6 +120,7 @@ int		gem_eint(struct gem_softc *, u_int);
 int		gem_rint(struct gem_softc *);
 int		gem_tint(struct gem_softc *, u_int32_t);
 int		gem_pint(struct gem_softc *);
+void		gem_rxcksum(struct mbuf *, u_int64_t);
 
 #ifdef GEM_DEBUG
 #define	DPRINTF(sc, x)	if ((sc)->sc_arpcom.ac_if.if_flags & IFF_DEBUG) \
@@ -803,7 +808,9 @@ gem_init(struct ifnet *ifp)
 
 	/* Encode Receive Descriptor ring size: four possible values */
 	v = gem_ringsize(GEM_NRXDESC /*XXX*/);
-
+	/* RX TCP/UDP checksum offset */
+	v |= ((ETHER_HDR_LEN + sizeof(struct ip)) <<
+	    GEM_RX_CONFIG_CXM_START_SHFT);
 	/* Enable DMA */
 	bus_space_write_4(t, h, GEM_RX_CONFIG, 
 		v|(GEM_THRSH_1024<<GEM_RX_CONFIG_FIFO_THRS_SHIFT)|
@@ -938,6 +945,95 @@ gem_init_regs(struct gem_softc *sc)
 }
 
 /*
+ * RX TCP/UDP checksum
+ */
+void
+gem_rxcksum(struct mbuf *m, u_int64_t rxstat)
+{
+	struct ether_header *eh;
+	struct ip *ip;
+	struct udphdr *uh;
+	int32_t hlen, len, pktlen;
+	u_int16_t cksum, *opts;
+	u_int32_t temp32;
+	union pseudoh {
+		struct hdr {
+			u_int16_t len;
+			u_int8_t ttl;
+			u_int8_t proto;
+			u_int32_t src;
+			u_int32_t dst;
+		} h;
+		u_int16_t w[6];
+	} ph;
+
+	pktlen = m->m_pkthdr.len;
+	if (pktlen < sizeof(struct ether_header))
+		return;
+	eh = mtod(m, struct ether_header *);
+	if (eh->ether_type != htons(ETHERTYPE_IP))
+		return;
+	ip = (struct ip *)(eh + 1);
+	if (ip->ip_v != IPVERSION)
+		return;
+
+	hlen = ip->ip_hl << 2;
+	pktlen -= sizeof(struct ether_header);
+	if (hlen < sizeof(struct ip))
+		return;
+	if (ntohs(ip->ip_len) < hlen)
+		return;
+	if (ntohs(ip->ip_len) != pktlen) 
+		return;
+	if (ip->ip_off & htons(IP_MF | IP_OFFMASK))
+		return;	/* can't handle fragmented packet */
+
+	switch (ip->ip_p) {
+	case IPPROTO_TCP:
+		if (pktlen < (hlen + sizeof(struct tcphdr)))
+			return;
+		break;
+	case IPPROTO_UDP:
+		if (pktlen < (hlen + sizeof(struct udphdr)))
+			return;
+		uh = (struct udphdr *)((caddr_t)ip + hlen);
+		if (uh->uh_sum == 0)
+			return; /* no checksum */
+		break;
+	default:
+		return;
+	}
+
+	cksum = htons(~(rxstat & GEM_RD_CHECKSUM));
+	/* cksum fixup for IP options */
+	len = hlen - sizeof(struct ip);
+	if (len > 0) {
+		opts = (u_int16_t *)(ip + 1);
+		for (; len > 0; len -= sizeof(u_int16_t), opts++) {
+			temp32 = cksum - *opts;
+			temp32 = (temp32 >> 16) + (temp32 & 65535);
+			cksum = temp32 & 65535;
+		}
+	}
+
+	ph.h.len = htons(ntohs(ip->ip_len) - hlen);
+	ph.h.ttl = 0;
+	ph.h.proto = ip->ip_p;
+	ph.h.src = ip->ip_src.s_addr;
+	ph.h.dst = ip->ip_dst.s_addr;
+	temp32 = cksum;
+	opts = &ph.w[0];
+	temp32 += opts[0] + opts[1] + opts[2] + opts[3] + opts[4] + opts[5];
+	temp32 = (temp32 >> 16) + (temp32 & 65535);
+	temp32 += (temp32 >> 16);
+	cksum = ~temp32;
+	if (cksum == 0) {
+		m->m_pkthdr.csum_flags |=
+			M_TCP_CSUM_IN_OK | M_UDP_CSUM_IN_OK;
+	}
+}
+
+/*
  * Receive interrupt.
  */
 int
@@ -1002,6 +1098,8 @@ gem_rint(struct gem_softc *sc)
 		m->m_pkthdr.rcvif = ifp;
 		m->m_pkthdr.len = m->m_len = len;
 
+		gem_rxcksum(m, rxstat);	
+
 #if NBPFILTER > 0
 		if (ifp->if_bpf)
 			bpf_mtap(ifp->if_bpf, m, BPF_DIRECTION_IN);