[Patch net-next v1 07/12] net: dsa: microchip: ptp: add packet reception timestamping

Arun Ramadoss
2022-11-28T10:34:44Z

From: Christian Eggers <ceggers@arri.de>

This patch adds the routines for timestamping received ptp packets.
Whenever the ptp packet is received, the 4 byte hardware time stamped
value is append to its packet. This 4 byte value is extracted from the
tail tag and reconstructed to absolute time and assigned to skb
hwtstamp.

Signed-off-by: Christian Eggers <ceggers@arri.de>
Co-developed-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>

---
RFC v2 -> Patch v1
- Fixed compilation issue
---
drivers/net/dsa/microchip/ksz_common.c | 13 +++++
drivers/net/dsa/microchip/ksz_ptp.c | 28 +++++++++++
drivers/net/dsa/microchip/ksz_ptp.h | 6 +++
include/linux/dsa/ksz_common.h | 15 ++++++
net/dsa/tag_ksz.c | 68 +++++++++++++++++++++++---
5 files changed, 124 insertions(+), 6 deletions(-)

diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 9bfd7dd5cd31..306bdc1469d2 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -5,6 +5,7 @@
* Copyright (C) 2017-2019 Microchip Technology Inc.
*/

+#include <linux/dsa/ksz_common.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/gpio/consumer.h>
@@ -2453,6 +2454,17 @@ static enum dsa_tag_protocol ksz_get_tag_protocol(struct dsa_switch *ds,
return proto;
}

+static int ksz_connect_tag_protocol(struct dsa_switch *ds,
+ enum dsa_tag_protocol proto)
+{
+ struct ksz_tagger_data *tagger_data;
+
+ tagger_data = ksz_tagger_data(ds);
+ tagger_data->meta_tstamp_handler = ksz_tstamp_reconstruct;
+
+ return 0;
+}
+
static int ksz_port_vlan_filtering(struct dsa_switch *ds, int port,
bool flag, struct netlink_ext_ack *extack)
{
@@ -2849,6 +2861,7 @@ static int ksz_switch_detect(struct ksz_device *dev)

static const struct dsa_switch_ops ksz_switch_ops = {
.get_tag_protocol = ksz_get_tag_protocol,
+ .connect_tag_protocol = ksz_connect_tag_protocol,
.get_phy_flags = ksz_get_phy_flags,
.setup = ksz_setup,
.teardown = ksz_teardown,
diff --git a/drivers/net/dsa/microchip/ksz_ptp.c b/drivers/net/dsa/microchip/ksz_ptp.c
index 515a40c9f107..d878e922c275 100644
--- a/drivers/net/dsa/microchip/ksz_ptp.c
+++ b/drivers/net/dsa/microchip/ksz_ptp.c
@@ -353,6 +353,34 @@ static int ksz_ptp_start_clock(struct ksz_device *dev)
return 0;
}

+ktime_t ksz_tstamp_reconstruct(struct dsa_switch *ds, ktime_t tstamp)
+{
+ struct ksz_device *dev = ds->priv;
+ struct timespec64 ptp_clock_time;
+ struct ksz_ptp_data *ptp_data;
+ struct timespec64 diff;
+ struct timespec64 ts;
+
+ ptp_data = &dev->ptp_data;
+ ts = ktime_to_timespec64(tstamp);
+
+ spin_lock_bh(&ptp_data->clock_lock);
+ ptp_clock_time = ptp_data->clock_time;
+ spin_unlock_bh(&ptp_data->clock_lock);
+
+ /* calculate full time from partial time stamp */
+ ts.tv_sec = (ptp_clock_time.tv_sec & ~3) | ts.tv_sec;
+
+ /* find nearest possible point in time */
+ diff = timespec64_sub(ts, ptp_clock_time);
+ if (diff.tv_sec > 2)
+ ts.tv_sec -= 4;
+ else if (diff.tv_sec < -2)
+ ts.tv_sec += 4;
+
+ return timespec64_to_ktime(ts);
+}
+
static const struct ptp_clock_info ksz_ptp_caps = {
.owner = THIS_MODULE,
.name = "Microchip Clock",
diff --git a/drivers/net/dsa/microchip/ksz_ptp.h b/drivers/net/dsa/microchip/ksz_ptp.h
index 5cec8f2e8420..13c06c24b488 100644
--- a/drivers/net/dsa/microchip/ksz_ptp.h
+++ b/drivers/net/dsa/microchip/ksz_ptp.h
@@ -30,6 +30,7 @@ int ksz_hwtstamp_get(struct dsa_switch *ds, int port, struct ifreq *ifr);
int ksz_hwtstamp_set(struct dsa_switch *ds, int port, struct ifreq *ifr);
int ksz_ptp_irq_setup(struct dsa_switch *ds, u8 p);
void ksz_ptp_irq_free(struct dsa_switch *ds, u8 p);
+ktime_t ksz_tstamp_reconstruct(struct dsa_switch *ds, ktime_t tstamp);

#else

@@ -66,6 +67,11 @@ static inline int ksz_ptp_irq_setup(struct dsa_switch *ds, u8 p)

static inline void ksz_ptp_irq_free(struct dsa_switch *ds, u8 p) {}

+static inline ktime_t ksz_tstamp_reconstruct(struct dsa_switch *ds, ktime_t tstamp)
+{
+ return 0;
+}
+
#endif /* End of CONFIG_NET_DSA_MICROCHIP_KSZ_PTP */

#endif
diff --git a/include/linux/dsa/ksz_common.h b/include/linux/dsa/ksz_common.h
index 62996860b887..0be0cd903727 100644
--- a/include/linux/dsa/ksz_common.h
+++ b/include/linux/dsa/ksz_common.h
@@ -9,9 +9,24 @@

#include <net/dsa.h>

+/* All time stamps from the KSZ consist of 2 bits for seconds and 30 bits for
+ * nanoseconds. This is NOT the same as 32 bits for nanoseconds.
+ */
+#define KSZ_TSTAMP_SEC_MASK GENMASK(31, 30)
+#define KSZ_TSTAMP_NSEC_MASK GENMASK(29, 0)
+
+static inline ktime_t ksz_decode_tstamp(u32 tstamp)
+{
+ u64 ns = FIELD_GET(KSZ_TSTAMP_SEC_MASK, tstamp) * NSEC_PER_SEC +
+ FIELD_GET(KSZ_TSTAMP_NSEC_MASK, tstamp);
+
+ return ns_to_ktime(ns);
+}
+
struct ksz_tagger_data {
bool (*hwtstamp_get_state)(struct dsa_switch *ds);
void (*hwtstamp_set_state)(struct dsa_switch *ds, bool on);
+ ktime_t (*meta_tstamp_handler)(struct dsa_switch *ds, ktime_t tstamp);
};

static inline struct ksz_tagger_data *
diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c
index 828af38f0598..41ce5ff5ed41 100644
--- a/net/dsa/tag_ksz.c
+++ b/net/dsa/tag_ksz.c
@@ -7,6 +7,7 @@
#include <linux/dsa/ksz_common.h>
#include <linux/etherdevice.h>
#include <linux/list.h>
+#include <linux/ptp_classify.h>
#include <net/dsa.h>

#include "tag.h"
@@ -157,10 +158,11 @@ MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ8795, KSZ8795_NAME);
* tag0 : Prioritization (not used now)
* tag1 : each bit represents port (eg, 0x01=port1, 0x02=port2, 0x10=port5)
*
- * For Egress (KSZ9477 -> Host), 1 byte is added before FCS.
+ * For Egress (KSZ9477 -> Host), 1/5 bytes is added before FCS.
* ---------------------------------------------------------------------------
- * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag0(1byte)|FCS(4bytes)
+ * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|ts(4bytes)|tag0(1byte)|FCS(4bytes)
* ---------------------------------------------------------------------------
+ * ts : time stamp (Present only if bit 7 of tag0 is set)
* tag0 : zero-based value represents port
* (eg, 0x00=port1, 0x02=port3, 0x06=port7)
*/
@@ -172,6 +174,57 @@ MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ8795, KSZ8795_NAME);
#define KSZ9477_TAIL_TAG_OVERRIDE BIT(9)
#define KSZ9477_TAIL_TAG_LOOKUP BIT(10)

+static void ksz_rcv_timestamp(struct sk_buff *skb, u8 *tag,
+ struct net_device *dev, unsigned int port)
+{
+ struct skb_shared_hwtstamps *hwtstamps = skb_hwtstamps(skb);
+ struct dsa_switch *ds = dev->dsa_ptr->ds;
+ u8 *tstamp_raw = tag - KSZ_PTP_TAG_LEN;
+ struct ksz_tagger_data *tagger_data;
+ struct ptp_header *ptp_hdr;
+ unsigned int ptp_type;
+ u8 ptp_msg_type;
+ ktime_t tstamp;
+ s64 correction;
+
+ tagger_data = ksz_tagger_data(ds);
+ if (!tagger_data->meta_tstamp_handler)
+ return;
+
+ /* convert time stamp and write to skb */
+ tstamp = ksz_decode_tstamp(get_unaligned_be32(tstamp_raw));
+ memset(hwtstamps, 0, sizeof(*hwtstamps));
+ hwtstamps->hwtstamp = tagger_data->meta_tstamp_handler(ds, tstamp);
+
+ if (skb_headroom(skb) < ETH_HLEN)
+ return;
+
+ __skb_push(skb, ETH_HLEN);
+ ptp_type = ptp_classify_raw(skb);
+ __skb_pull(skb, ETH_HLEN);
+
+ if (ptp_type == PTP_CLASS_NONE)
+ return;
+
+ ptp_hdr = ptp_parse_header(skb, ptp_type);
+ if (!ptp_hdr)
+ return;
+
+ ptp_msg_type = ptp_get_msgtype(ptp_hdr, ptp_type);
+ if (ptp_msg_type != PTP_MSGTYPE_PDELAY_REQ)
+ return;
+
+ /* Only subtract the partial time stamp from the correction field. When
+ * the hardware adds the egress time stamp to the correction field of
+ * the PDelay_Resp message on tx, also only the partial time stamp will
+ * be added.
+ */
+ correction = (s64)get_unaligned_be64(&ptp_hdr->correction);
+ correction -= ktime_to_ns(tstamp) << 16;
+
+ ptp_header_update_correction(skb, ptp_type, ptp_hdr, correction);
+}
+
/* Time stamp tag is only inserted if PTP is enabled in hardware. */
static void ksz_xmit_timestamp(struct dsa_port *dp, struct sk_buff *skb)
{
@@ -220,8 +273,10 @@ static struct sk_buff *ksz9477_rcv(struct sk_buff *skb, struct net_device *dev)
unsigned int len = KSZ_EGRESS_TAG_LEN;

/* Extra 4-bytes PTP timestamp */
- if (tag[0] & KSZ9477_PTP_TAG_INDICATION)
- len += KSZ9477_PTP_TAG_LEN;
+ if (tag[0] & KSZ9477_PTP_TAG_INDICATION) {
+ ksz_rcv_timestamp(skb, tag, dev, port);
+ len += KSZ_PTP_TAG_LEN;
+ }

return ksz_common_rcv(skb, dev, port, len);
}
@@ -287,10 +342,11 @@ MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ9893, KSZ9893_NAME);
* tag0 : represents tag override, lookup and valid
* tag1 : each bit represents port (eg, 0x01=port1, 0x02=port2, 0x80=port8)
*
- * For rcv, 1 byte is added before FCS.
+ * For rcv, 1/5 bytes is added before FCS.
* ---------------------------------------------------------------------------
- * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag0(1byte)|FCS(4bytes)
+ * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|ts(4bytes)|tag0(1byte)|FCS(4bytes)
* ---------------------------------------------------------------------------
+ * ts : time stamp (Present only if bit 7 of tag0 is set)
* tag0 : zero-based value represents port
* (eg, 0x00=port1, 0x02=port3, 0x07=port8)
*/
--
2.36.1