[PATCH 4/5] net: dsa: ksz: Add KSZ8795 tag code

[Marek Vasut <marex@denx.de>]

From: Tristram Ha <Tristram.Ha@microchip.com>

Add DSA tag code for Microchip KSZ8795 switch. The switch is simpler
and the tag is only 1 byte, instead of 2 as is the case with KSZ9477.

Signed-off-by: Tristram Ha <Tristram.Ha@microchip.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Cc: Woojung Huh <woojung.huh@microchip.com>
Cc: David S. Miller <davem@davemloft.net>
---
 include/net/dsa.h  |  1 +
 net/dsa/Kconfig    |  4 ++++
 net/dsa/dsa.c      |  3 +++
 net/dsa/dsa_priv.h |  1 +
 net/dsa/tag_ksz.c  | 59 ++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 68 insertions(+)

diff --git a/include/net/dsa.h b/include/net/dsa.h
index dff6afc22ab1e..7aee9c33ceb78 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -35,6 +35,7 @@ enum dsa_tag_protocol {
 	DSA_TAG_PROTO_BRCM_PREPEND,
 	DSA_TAG_PROTO_DSA,
 	DSA_TAG_PROTO_EDSA,
+	DSA_TAG_PROTO_KSZ8795,
 	DSA_TAG_PROTO_KSZ9477,
 	DSA_TAG_PROTO_LAN9303,
 	DSA_TAG_PROTO_MTK,
diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
index 8cdf73a31374e..0059237d50ec3 100644
--- a/net/dsa/Kconfig
+++ b/net/dsa/Kconfig
@@ -41,6 +41,10 @@ config NET_DSA_TAG_EDSA
 config NET_DSA_TAG_KSZ
 	bool
 
+config NET_DSA_TAG_KSZ8795
+	bool
+	select NET_DSA_TAG_KSZ
+
 config NET_DSA_TAG_KSZ9477
 	bool
 	select NET_DSA_TAG_KSZ
diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 4d4a381367d4d..bf009192b0d53 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -52,6 +52,9 @@ const struct dsa_device_ops *dsa_device_ops[DSA_TAG_LAST] = {
 #ifdef CONFIG_NET_DSA_TAG_EDSA
 	[DSA_TAG_PROTO_EDSA] = &edsa_netdev_ops,
 #endif
+#ifdef CONFIG_NET_DSA_TAG_KSZ8795
+	[DSA_TAG_PROTO_KSZ8795] = &ksz8795_netdev_ops,
+#endif
 #ifdef CONFIG_NET_DSA_TAG_KSZ9477
 	[DSA_TAG_PROTO_KSZ9477] = &ksz9477_netdev_ops,
 #endif
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index b48b533294544..903c5118d5cbf 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -206,6 +206,7 @@ extern const struct dsa_device_ops dsa_netdev_ops;
 extern const struct dsa_device_ops edsa_netdev_ops;
 
 /* tag_ksz.c */
+extern const struct dsa_device_ops ksz8795_netdev_ops;
 extern const struct dsa_device_ops ksz9477_netdev_ops;
 
 /* tag_lan9303.c */
diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c
index d94bad1ab7e53..ee05629b5a342 100644
--- a/net/dsa/tag_ksz.c
+++ b/net/dsa/tag_ksz.c
@@ -88,6 +88,65 @@ static struct sk_buff *ksz_rcv(struct sk_buff *skb, struct net_device *dev,
 	return skb;
 }
 
+/*
+ * For Ingress (Host -> KSZ8795), 1 byte is added before FCS.
+ * ---------------------------------------------------------------------------
+ * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag(1byte)|FCS(4bytes)
+ * ---------------------------------------------------------------------------
+ * tag : each bit represents port (eg, 0x01=port1, 0x02=port2, 0x10=port5)
+ *
+ * For Egress (KSZ8795 -> Host), 1 byte is added before FCS.
+ * ---------------------------------------------------------------------------
+ * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag0(1byte)|FCS(4bytes)
+ * ---------------------------------------------------------------------------
+ * tag0 : zero-based value represents port
+ *	  (eg, 0x00=port1, 0x02=port3, 0x06=port7)
+ */
+
+#define	KSZ8795_INGRESS_TAG_LEN		1
+
+#define KSZ8795_TAIL_TAG_OVERRIDE	BIT(6)
+#define KSZ8795_TAIL_TAG_LOOKUP		BIT(7)
+
+static void ksz8795_get_tag(u8 *tag, unsigned int *port, unsigned int *len)
+{
+	*port = tag[0] & 7;
+	*len = KSZ_EGRESS_TAG_LEN;
+}
+
+static void ksz8795_set_tag(struct sk_buff *skb, struct net_device *dev)
+{
+	struct dsa_port *dp = dsa_slave_to_port(dev);
+	u8 *tag = skb_put(skb, KSZ8795_INGRESS_TAG_LEN);
+	u8 *addr = skb_mac_header(skb);
+
+	*tag = 1 << dp->index;
+	if (!memcmp(addr, special_mult_addr, ETH_ALEN))
+		*tag |= KSZ8795_TAIL_TAG_OVERRIDE;
+}
+
+static struct ksz_tag_ops ksz8795_tag_ops = {
+	.get_tag	= ksz8795_get_tag,
+	.set_tag	= ksz8795_set_tag,
+};
+
+static struct sk_buff *ksz8795_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	return ksz_xmit(skb, dev, &ksz8795_tag_ops, KSZ8795_INGRESS_TAG_LEN);
+}
+
+static struct sk_buff *ksz8795_rcv(struct sk_buff *skb, struct net_device *dev,
+				  struct packet_type *pt)
+{
+	return ksz_rcv(skb, dev, pt, &ksz8795_tag_ops);
+}
+
+const struct dsa_device_ops ksz8795_netdev_ops = {
+	.xmit	= ksz8795_xmit,
+	.rcv	= ksz8795_rcv,
+	.overhead = KSZ8795_INGRESS_TAG_LEN,
+};
+
 /*
  * For Ingress (Host -> KSZ9477), 2 bytes are added before FCS.
  * ---------------------------------------------------------------------------
-- 
2.18.0