[PATCH net-next v5 6/9] net: dsa: microchip: Add KSZ8463 tail tag handling
From: Bastien Curutchet (Schneider Electric)
Date: Thu Feb 26 2026 - 12:42:43 EST
KSZ8463 uses the KSZ9893 DSA TAG driver. However, the KSZ8463 doesn't
use the tail tag to convey timestamps to the host as KSZ9893 does. It
uses the reserved fields in the PTP header instead.
Add a KSZ8463-specifig DSA_TAG driver to handle KSZ8463 timestamps.
There is no information in the tail tag to distinguish PTP packets from
others so use the ptp_classify_raw() helper to find the PTP packets and
extract the timestamp from their PTP headers.
Signed-off-by: Bastien Curutchet (Schneider Electric) <bastien.curutchet@xxxxxxxxxxx>
---
drivers/net/dsa/microchip/ksz_common.c | 5 ++-
include/net/dsa.h | 2 ++
net/dsa/tag_ksz.c | 62 ++++++++++++++++++++++++++++++++++
3 files changed, 68 insertions(+), 1 deletion(-)
diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 7deeb0b86793bab4818a7e70bc468346ec8f22e3..4b36a3b88f49363273e72d19f9625e542bff1b06 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -3580,8 +3580,10 @@ static enum dsa_tag_protocol ksz_get_tag_protocol(struct dsa_switch *ds,
if (ksz_is_ksz87xx(dev) || ksz_is_8895_family(dev))
proto = DSA_TAG_PROTO_KSZ8795;
+ if (dev->chip_id == KSZ8463_CHIP_ID)
+ proto = DSA_TAG_PROTO_KSZ8463;
+
if (dev->chip_id == KSZ88X3_CHIP_ID ||
- dev->chip_id == KSZ8463_CHIP_ID ||
dev->chip_id == KSZ8563_CHIP_ID ||
dev->chip_id == KSZ9893_CHIP_ID ||
dev->chip_id == KSZ9563_CHIP_ID)
@@ -3609,6 +3611,7 @@ static int ksz_connect_tag_protocol(struct dsa_switch *ds,
switch (proto) {
case DSA_TAG_PROTO_KSZ8795:
return 0;
+ case DSA_TAG_PROTO_KSZ8463:
case DSA_TAG_PROTO_KSZ9893:
case DSA_TAG_PROTO_KSZ9477:
case DSA_TAG_PROTO_LAN937X:
diff --git a/include/net/dsa.h b/include/net/dsa.h
index 6c17446f3dcc29682e07a70362bae8d8fa6233b0..e854cde8b400c2f47e5c474460e914e1abbf8984 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -58,6 +58,7 @@ struct tc_action;
#define DSA_TAG_PROTO_YT921X_VALUE 30
#define DSA_TAG_PROTO_MXL_GSW1XX_VALUE 31
#define DSA_TAG_PROTO_MXL862_VALUE 32
+#define DSA_TAG_PROTO_KSZ8463_VALUE 33
enum dsa_tag_protocol {
DSA_TAG_PROTO_NONE = DSA_TAG_PROTO_NONE_VALUE,
@@ -93,6 +94,7 @@ enum dsa_tag_protocol {
DSA_TAG_PROTO_YT921X = DSA_TAG_PROTO_YT921X_VALUE,
DSA_TAG_PROTO_MXL_GSW1XX = DSA_TAG_PROTO_MXL_GSW1XX_VALUE,
DSA_TAG_PROTO_MXL862 = DSA_TAG_PROTO_MXL862_VALUE,
+ DSA_TAG_PROTO_KSZ8463 = DSA_TAG_PROTO_KSZ8463_VALUE,
};
struct dsa_switch;
diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c
index 6ec9bcb324a953d988ef665a177566159e27027f..310390ce08c207a1d872de8ffc4ce1f301f0f1c7 100644
--- a/net/dsa/tag_ksz.c
+++ b/net/dsa/tag_ksz.c
@@ -12,6 +12,7 @@
#include "tag.h"
+#define KSZ8463_NAME "ksz8463"
#define KSZ8795_NAME "ksz8795"
#define KSZ9477_NAME "ksz9477"
#define KSZ9893_NAME "ksz9893"
@@ -382,6 +383,66 @@ static const struct dsa_device_ops ksz9893_netdev_ops = {
DSA_TAG_DRIVER(ksz9893_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ9893, KSZ9893_NAME);
+#define KSZ8463_TAIL_TAG_PRIO GENMASK(4, 3)
+#define KSZ8463_TAIL_TAG_EG_PORT_M GENMASK(2, 0)
+
+static struct sk_buff *ksz8463_xmit(struct sk_buff *skb,
+ struct net_device *dev)
+{
+ u16 queue_mapping = skb_get_queue_mapping(skb);
+ u8 prio = netdev_txq_to_tc(dev, queue_mapping);
+
+ return ksz_common_xmit(skb, dev, false,
+ FIELD_PREP(KSZ8463_TAIL_TAG_PRIO, prio),
+ 0);
+}
+
+static struct sk_buff *ksz8463_rcv(struct sk_buff *skb, struct net_device *dev)
+{
+ unsigned int len = KSZ_EGRESS_TAG_LEN;
+ struct ptp_header *ptp_hdr;
+ unsigned int ptp_class;
+ unsigned int port;
+ ktime_t tstamp;
+ u8 *tag;
+
+ if (skb_linearize(skb))
+ return NULL;
+
+ /* Tag decoding */
+ tag = skb_tail_pointer(skb) - KSZ_EGRESS_TAG_LEN;
+ port = tag[0] & KSZ8463_TAIL_TAG_EG_PORT_M;
+
+ __skb_push(skb, ETH_HLEN);
+ ptp_class = ptp_classify_raw(skb);
+ __skb_pull(skb, ETH_HLEN);
+ if (ptp_class == PTP_CLASS_NONE)
+ goto common_rcv;
+
+ ptp_hdr = ptp_parse_header(skb, ptp_class);
+ if (ptp_hdr) {
+ tstamp = ksz_decode_tstamp(get_unaligned_be32(&ptp_hdr->reserved2));
+ KSZ_SKB_CB(skb)->tstamp = tstamp;
+ ptp_hdr->reserved2 = 0;
+ }
+
+common_rcv:
+ return ksz_common_rcv(skb, dev, port, len);
+}
+
+static const struct dsa_device_ops ksz8463_netdev_ops = {
+ .name = KSZ8463_NAME,
+ .proto = DSA_TAG_PROTO_KSZ8463,
+ .xmit = ksz8463_xmit,
+ .rcv = ksz8463_rcv,
+ .connect = ksz_connect,
+ .disconnect = ksz_disconnect,
+ .needed_tailroom = KSZ_INGRESS_TAG_LEN,
+};
+
+DSA_TAG_DRIVER(ksz8463_netdev_ops);
+MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ8463, KSZ8463_NAME);
+
/* For xmit, 2/6 bytes are added before FCS.
* ---------------------------------------------------------------------------
* DA(6bytes)|SA(6bytes)|....|Data(nbytes)|ts(4bytes)|tag0(1byte)|tag1(1byte)|
@@ -452,6 +513,7 @@ DSA_TAG_DRIVER(lan937x_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_LAN937X, LAN937X_NAME);
static struct dsa_tag_driver *dsa_tag_driver_array[] = {
+ &DSA_TAG_DRIVER_NAME(ksz8463_netdev_ops),
&DSA_TAG_DRIVER_NAME(ksz8795_netdev_ops),
&DSA_TAG_DRIVER_NAME(ksz9477_netdev_ops),
&DSA_TAG_DRIVER_NAME(ksz9893_netdev_ops),
--
2.53.0