net: dsa: add tagging driver for MaxLinear GSW1xx switch family

Add support for a new DSA tagging protocol driver for the MaxLinear
GSW1xx switch family. The GSW1xx switches use a proprietary 8-byte
special tag inserted between the source MAC address and the EtherType
field to indicate the source and destination ports for frames
traversing the CPU port.

Implement the tag handling logic to insert the special tag on transmit
and parse it on receive.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Tested-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Link: https://patch.msgid.link/0e973ebfd9433c30c96f50670da9e9449a0d98f2.1762170107.git.daniel@makrotopia.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/MAINTAINERS b/MAINTAINERS
index 12cd8a5ab274826d7539b2976ac897051195729a..0dc4aa37d9034aef954969f64c65ba761d9f7a76 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14053,7 +14053,7 @@ F:      tools/testing/selftests/landlock/
 K:     landlock
 K:     LANDLOCK
 
-LANTIQ / INTEL Ethernet drivers
+LANTIQ / MAXLINEAR / INTEL Ethernet DSA drivers
 M:     Hauke Mehrtens <hauke@hauke-m.de>
 L:     netdev@vger.kernel.org
 S:     Maintained
@@ -14061,6 +14061,7 @@ F:      Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
 F:     drivers/net/dsa/lantiq/*
 F:     drivers/net/ethernet/lantiq_xrx200.c
 F:     net/dsa/tag_gswip.c
+F:     net/dsa/tag_mxl-gsw1xx.c
 
 LANTIQ MIPS ARCHITECTURE
 M:     John Crispin <john@phrozen.org>

diff --git a/include/net/dsa.h b/include/net/dsa.h
index 67762fdaf3c7a552691ca2739ae32a0b88337de0..2df2e2ead9a815fe6a9f2d6160960a51c874cfb6 100644 (file)
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -56,6 +56,7 @@ struct tc_action;
 #define DSA_TAG_PROTO_VSC73XX_8021Q_VALUE      28
 #define DSA_TAG_PROTO_BRCM_LEGACY_FCS_VALUE    29
 #define DSA_TAG_PROTO_YT921X_VALUE             30
+#define DSA_TAG_PROTO_MXL_GSW1XX_VALUE         31
 
 enum dsa_tag_protocol {
        DSA_TAG_PROTO_NONE              = DSA_TAG_PROTO_NONE_VALUE,
@@ -89,6 +90,7 @@ enum dsa_tag_protocol {
        DSA_TAG_PROTO_LAN937X           = DSA_TAG_PROTO_LAN937X_VALUE,
        DSA_TAG_PROTO_VSC73XX_8021Q     = DSA_TAG_PROTO_VSC73XX_8021Q_VALUE,
        DSA_TAG_PROTO_YT921X            = DSA_TAG_PROTO_YT921X_VALUE,
+       DSA_TAG_PROTO_MXL_GSW1XX        = DSA_TAG_PROTO_MXL_GSW1XX_VALUE,
 };
 
 struct dsa_switch;

diff --git a/include/uapi/linux/if_ether.h b/include/uapi/linux/if_ether.h
index cfd200c87e5ea30fd579a390e24f70e9c611e471..2c93b7b731c8fec9c6e6f76ef01356e017fb8802 100644 (file)
--- a/include/uapi/linux/if_ether.h
+++ b/include/uapi/linux/if_ether.h
@@ -92,6 +92,7 @@
 #define ETH_P_ETHERCAT 0x88A4          /* EtherCAT                     */
 #define ETH_P_8021AD   0x88A8          /* 802.1ad Service VLAN         */
 #define ETH_P_802_EX1  0x88B5          /* 802.1 Local Experimental 1.  */
+#define ETH_P_MXLGSW   0x88C3          /* MaxLinear GSW DSA [ NOT AN OFFICIALLY REGISTERED ID ] */
 #define ETH_P_PREAUTH  0x88C7          /* 802.11 Preauthentication */
 #define ETH_P_TIPC     0x88CA          /* TIPC                         */
 #define ETH_P_LLDP     0x88CC          /* Link Layer Discovery Protocol */

diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
index 6b94028b1fcc237496e9b4d499dac9bde2f4db2f..f86b30742122fc32e964080a4bb5b9f7a756fa99 100644 (file)
--- a/net/dsa/Kconfig
+++ b/net/dsa/Kconfig
@@ -104,6 +104,14 @@ config NET_DSA_TAG_MTK
          Say Y or M if you want to enable support for tagging frames for
          Mediatek switches.
 
+config NET_DSA_TAG_MXL_GSW1XX
+       tristate "Tag driver for MaxLinear GSW1xx switches"
+       help
+         The GSW1xx family of switches supports an 8-byte special tag which
+         can be used on the CPU port of the switch.
+         Say Y or M if you want to enable support for tagging frames for
+         MaxLinear GSW1xx switches.
+
 config NET_DSA_TAG_KSZ
        tristate "Tag driver for Microchip 8795/937x/9477/9893 families of switches"
        help

diff --git a/net/dsa/Makefile b/net/dsa/Makefile
index 4b011a1d5c87ebbe65adcf38927d79560e12aec1..42d173f5a7013ae7539eb441a872b0fc5d8229cd 100644 (file)
--- a/net/dsa/Makefile
+++ b/net/dsa/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_NET_DSA_TAG_HELLCREEK) += tag_hellcreek.o
 obj-$(CONFIG_NET_DSA_TAG_KSZ) += tag_ksz.o
 obj-$(CONFIG_NET_DSA_TAG_LAN9303) += tag_lan9303.o
 obj-$(CONFIG_NET_DSA_TAG_MTK) += tag_mtk.o
+obj-$(CONFIG_NET_DSA_TAG_MXL_GSW1XX) += tag_mxl-gsw1xx.o
 obj-$(CONFIG_NET_DSA_TAG_NONE) += tag_none.o
 obj-$(CONFIG_NET_DSA_TAG_OCELOT) += tag_ocelot.o
 obj-$(CONFIG_NET_DSA_TAG_OCELOT_8021Q) += tag_ocelot_8021q.o

diff --git a/net/dsa/tag_mxl-gsw1xx.c b/net/dsa/tag_mxl-gsw1xx.c
new file mode 100644 (file)
index 0000000..701a079
--- /dev/null
+++ b/net/dsa/tag_mxl-gsw1xx.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * DSA driver Special Tag support for MaxLinear GSW1xx switch chips
+ *
+ * Copyright (C) 2025 Daniel Golle <daniel@makrotopia.org>
+ * Copyright (C) 2023 - 2024 MaxLinear Inc.
+ */
+
+#include <linux/bitops.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+#include <net/dsa.h>
+
+#include "tag.h"
+
+/* To define the outgoing port and to discover the incoming port a special
+ * tag is used by the GSW1xx.
+ *
+ *       Dest MAC       Src MAC    special TAG        EtherType
+ * ...| 1 2 3 4 5 6 | 1 2 3 4 5 6 | 1 2 3 4 5 6 7 8 | 1 2 |...
+ *                                |<--------------->|
+ */
+
+#define GSW1XX_TAG_NAME                "gsw1xx"
+
+/* special tag header length (RX and TX) */
+#define GSW1XX_HEADER_LEN              8
+
+/* Word 0 = Ethertype -> 0x88C3 */
+
+/* Word 1 */
+#define GSW1XX_TX_PORT_MAP             GENMASK(7, 0)
+#define GSW1XX_TX_PORT_MAP_EN          BIT(15)
+#define GSW1XX_TX_CLASS_EN             BIT(14)
+#define GSW1XX_TX_TIME_STAMP_EN                BIT(13)
+#define GSW1XX_TX_LRN_DIS              BIT(12)
+#define GSW1XX_TX_CLASS                        GENMASK(11, 8)
+
+/* special tag in RX path header */
+/* Word 2 */
+#define GSW1XX_RX_PORT_MAP             GENMASK(15, 8)
+
+static struct sk_buff *gsw1xx_tag_xmit(struct sk_buff *skb,
+                                      struct net_device *dev)
+{
+       struct dsa_port *dp = dsa_user_to_port(dev);
+       __be16 *gsw1xx_tag;
+
+       /* provide additional space 'GSW1XX_HEADER_LEN' bytes */
+       skb_push(skb, GSW1XX_HEADER_LEN);
+
+       /* add space between MAC address and Ethertype */
+       dsa_alloc_etype_header(skb, GSW1XX_HEADER_LEN);
+
+       /* special tag ingress */
+       gsw1xx_tag = dsa_etype_header_pos_tx(skb);
+       gsw1xx_tag[0] = htons(ETH_P_MXLGSW);
+       gsw1xx_tag[1] = htons(GSW1XX_TX_PORT_MAP_EN | GSW1XX_TX_LRN_DIS |
+                       FIELD_PREP(GSW1XX_TX_PORT_MAP, BIT(dp->index)));
+
+       gsw1xx_tag[2] = 0;
+       gsw1xx_tag[3] = 0;
+
+       return skb;
+}
+
+static struct sk_buff *gsw1xx_tag_rcv(struct sk_buff *skb,
+                                     struct net_device *dev)
+{
+       int port;
+       __be16 *gsw1xx_tag;
+
+       if (unlikely(!pskb_may_pull(skb, GSW1XX_HEADER_LEN))) {
+               dev_warn_ratelimited(&dev->dev, "Dropping packet, cannot pull SKB\n");
+               return NULL;
+       }
+
+       gsw1xx_tag = dsa_etype_header_pos_rx(skb);
+
+       if (unlikely(ntohs(gsw1xx_tag[0]) != ETH_P_MXLGSW)) {
+               dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid special tag\n");
+               dev_warn_ratelimited(&dev->dev, "Tag: %8ph\n", gsw1xx_tag);
+               return NULL;
+       }
+
+       /* Get source port information */
+       port = FIELD_GET(GSW1XX_RX_PORT_MAP, ntohs(gsw1xx_tag[1]));
+       skb->dev = dsa_conduit_find_user(dev, 0, port);
+       if (!skb->dev) {
+               dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\n");
+               dev_warn_ratelimited(&dev->dev, "Tag: %8ph\n", gsw1xx_tag);
+               return NULL;
+       }
+
+       /* remove the GSW1xx special tag between MAC addresses and the current
+        * ethertype field.
+        */
+       skb_pull_rcsum(skb, GSW1XX_HEADER_LEN);
+       dsa_strip_etype_header(skb, GSW1XX_HEADER_LEN);
+
+       return skb;
+}
+
+static const struct dsa_device_ops gsw1xx_netdev_ops = {
+       .name                   = GSW1XX_TAG_NAME,
+       .proto                  = DSA_TAG_PROTO_MXL_GSW1XX,
+       .xmit                   = gsw1xx_tag_xmit,
+       .rcv                    = gsw1xx_tag_rcv,
+       .needed_headroom        = GSW1XX_HEADER_LEN,
+};
+
+MODULE_DESCRIPTION("DSA tag driver for MaxLinear GSW1xx 8 byte protocol");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MXL_GSW1XX, GSW1XX_TAG_NAME);
+
+module_dsa_tag_driver(gsw1xx_netdev_ops);