[PATCH net-next 02/12] net: dsa: add Renesas RZ/N1 switch tag driver

Clément Léger
2022-04-14T12:26:22Z

The switch that is present on the Renesas RZ/N1 SoC uses a specific
VLAN value followed by 6 bytes which contains forwarding configuration.

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
---
net/dsa/Kconfig | 8 +++
net/dsa/Makefile | 1 +
net/dsa/tag_rzn1_a5psw.c | 112 +++++++++++++++++++++++++++++++++++++++
3 files changed, 121 insertions(+)
create mode 100644 net/dsa/tag_rzn1_a5psw.c

diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
index 8cb87b5067ee..e5b17108fa22 100644
--- a/net/dsa/Kconfig
+++ b/net/dsa/Kconfig
@@ -132,6 +132,13 @@ config NET_DSA_TAG_RTL8_4
Say Y or M if you want to enable support for tagging frames for Realtek
switches with 8 byte protocol 4 tags, such as the Realtek RTL8365MB-VC.

+config NET_DSA_TAG_RZN1_A5PSW
+ tristate "Tag driver for Renesas RZ/N1 A5PSW switch"
+ help
+ Say Y or M if you want to enable support for tagging frames for
+ Renesas RZ/N1 embedded switch that uses a 8 byte tag located after
+ destination MAC address.
+
config NET_DSA_TAG_LAN9303
tristate "Tag driver for SMSC/Microchip LAN9303 family of switches"
help
@@ -159,4 +166,5 @@ config NET_DSA_TAG_XRS700X
Say Y or M if you want to enable support for tagging frames for
Arrow SpeedChips XRS700x switches that use a single byte tag trailer.

+
endif
diff --git a/net/dsa/Makefile b/net/dsa/Makefile
index 9f75820e7c98..af28c24ead18 100644
--- a/net/dsa/Makefile
+++ b/net/dsa/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_NET_DSA_TAG_OCELOT_8021Q) += tag_ocelot_8021q.o
obj-$(CONFIG_NET_DSA_TAG_QCA) += tag_qca.o
obj-$(CONFIG_NET_DSA_TAG_RTL4_A) += tag_rtl4_a.o
obj-$(CONFIG_NET_DSA_TAG_RTL8_4) += tag_rtl8_4.o
+obj-$(CONFIG_NET_DSA_TAG_RZN1_A5PSW) += tag_rzn1_a5psw.o
obj-$(CONFIG_NET_DSA_TAG_SJA1105) += tag_sja1105.o
obj-$(CONFIG_NET_DSA_TAG_TRAILER) += tag_trailer.o
obj-$(CONFIG_NET_DSA_TAG_XRS700X) += tag_xrs700x.o
diff --git a/net/dsa/tag_rzn1_a5psw.c b/net/dsa/tag_rzn1_a5psw.c
new file mode 100644
index 000000000000..7818c1c0fca2
--- /dev/null
+++ b/net/dsa/tag_rzn1_a5psw.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 Schneider Electric
+ *
+ * Clément Léger <clement.leger@bootlin.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/etherdevice.h>
+#include <net/dsa.h>
+
+#include "dsa_priv.h"
+
+/* To define the outgoing port and to discover the incoming port a TAG is
+ * inserted after Src MAC :
+ *
+ * Dest MAC Src MAC TAG Type
+ * ...| 1 2 3 4 5 6 | 1 2 3 4 5 6 | 1 2 3 4 5 6 7 8 | 1 2 |...
+ * |<--------------->|
+ *
+ * See struct a5psw_tag for layout
+ */
+
+#define A5PSW_TAG_VALUE 0xE001
+#define A5PSW_TAG_LEN 8
+#define A5PSW_CTRL_DATA_FORCE_FORWARD BIT(0)
+/* This is both used for xmit tag and rcv tagging */
+#define A5PSW_CTRL_DATA_PORT GENMASK(3, 0)
+
+struct a5psw_tag {
+ u16 ctrl_tag;
+ u16 ctrl_data;
+ u32 ctrl_data2;
+};
+
+static struct sk_buff *a5psw_tag_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+ struct a5psw_tag *ptag, tag = {0};
+ struct dsa_port *dp = dsa_slave_to_port(dev);
+ u32 data2_val;
+
+ /* The Ethernet switch we are interfaced with needs packets to be at
+ * least 64 bytes (including FCS) otherwise they will be discarded when
+ * they enter the switch port logic. When tagging is enabled, we need
+ * to make sure that packets are at least 68 bytes (including FCS and
+ * tag).
+ */
+ if (__skb_put_padto(skb, ETH_ZLEN + sizeof(tag), false))
+ return NULL;
+
+ /* provide 'A5PSW_TAG_LEN' bytes additional space */
+ skb_push(skb, A5PSW_TAG_LEN);
+
+ /* make room between MACs and Ether-Type to insert tag */
+ dsa_alloc_etype_header(skb, A5PSW_TAG_LEN);
+
+ ptag = dsa_etype_header_pos_tx(skb);
+
+ data2_val = FIELD_PREP(A5PSW_CTRL_DATA_PORT, BIT(dp->index));
+ tag.ctrl_tag = htons(A5PSW_TAG_VALUE);
+ tag.ctrl_data = htons(A5PSW_CTRL_DATA_FORCE_FORWARD);
+ tag.ctrl_data2 = htonl(data2_val);
+
+ memcpy(ptag, &tag, sizeof(struct a5psw_tag));
+
+ return skb;
+}
+
+static struct sk_buff *a5psw_tag_rcv(struct sk_buff *skb,
+ struct net_device *dev)
+{
+ struct a5psw_tag *tag;
+ int port;
+
+ if (unlikely(!pskb_may_pull(skb, A5PSW_TAG_LEN))) {
+ dev_warn_ratelimited(&dev->dev,
+ "Dropping packet, cannot pull\n");
+ return NULL;
+ }
+
+ tag = dsa_etype_header_pos_rx(skb);
+
+ if (tag->ctrl_tag != htons(A5PSW_TAG_VALUE)) {
+ dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid TAG marker\n");
+ return NULL;
+ }
+
+ port = FIELD_GET(A5PSW_CTRL_DATA_PORT, ntohs(tag->ctrl_data));
+
+ skb->dev = dsa_master_find_slave(dev, 0, port);
+ if (!skb->dev)
+ return NULL;
+
+ skb_pull_rcsum(skb, A5PSW_TAG_LEN);
+ dsa_strip_etype_header(skb, A5PSW_TAG_LEN);
+
+ dsa_default_offload_fwd_mark(skb);
+
+ return skb;
+}
+
+static const struct dsa_device_ops a5psw_netdev_ops = {
+ .name = "a5psw",
+ .proto = DSA_TAG_PROTO_RZN1_A5PSW,
+ .xmit = a5psw_tag_xmit,
+ .rcv = a5psw_tag_rcv,
+ .needed_headroom = A5PSW_TAG_LEN,
+};
+
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_A5PSW);
+module_dsa_tag_driver(a5psw_netdev_ops);
--
2.34.1