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Subject[RFC Patch net-next 5/6] net: dsa: microchip: Adding the ptp packet reception logic
Date
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: Arun Ramadoss <arun.ramadoss@microchip.com>
---
drivers/net/dsa/microchip/ksz_common.c | 12 +++++++++++
drivers/net/dsa/microchip/ksz_ptp.c | 25 +++++++++++++++++++++
drivers/net/dsa/microchip/ksz_ptp.h | 6 ++++++
include/linux/dsa/ksz_common.h | 15 +++++++++++++
net/dsa/tag_ksz.c | 30 ++++++++++++++++++++++----
5 files changed, 84 insertions(+), 4 deletions(-)

diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 0c0fdb7b7879..388731959b23 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -2426,6 +2426,17 @@ 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)
{
@@ -2819,6 +2830,7 @@ 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 2cae543f7e0b..5ae6eedb6b39 100644
--- a/drivers/net/dsa/microchip/ksz_ptp.c
+++ b/drivers/net/dsa/microchip/ksz_ptp.c
@@ -372,6 +372,31 @@ 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 ksz_ptp_data *ptp_data = &dev->ptp_data;
+ struct timespec64 ts = ktime_to_timespec64(tstamp);
+ struct timespec64 ptp_clock_time;
+ struct timespec64 diff;
+
+ 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 7e5d374d2acf..9589909ab7d5 100644
--- a/drivers/net/dsa/microchip/ksz_ptp.h
+++ b/drivers/net/dsa/microchip/ksz_ptp.h
@@ -28,6 +28,7 @@ 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

@@ -64,6 +65,11 @@ 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_MICROCHIOP_KSZ_PTP */

#endif
diff --git a/include/linux/dsa/ksz_common.h b/include/linux/dsa/ksz_common.h
index 8903bce4753b..82edd7228b3c 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 ca1261b04fe7..937a3e70b471 100644
--- a/net/dsa/tag_ksz.c
+++ b/net/dsa/tag_ksz.c
@@ -164,6 +164,25 @@ MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ8795);
#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);
+ u8 *tstamp_raw = tag - KSZ9477_PTP_TAG_LEN;
+ struct dsa_switch *ds = dev->dsa_ptr->ds;
+ struct ksz_tagger_data *tagger_data;
+ ktime_t tstamp;
+
+ 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);
+}
+
static struct sk_buff *ksz9477_xmit(struct sk_buff *skb,
struct net_device *dev)
{
@@ -197,8 +216,10 @@ 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)
+ if (tag[0] & KSZ9477_PTP_TAG_INDICATION) {
+ ksz_rcv_timestamp(skb, tag, dev, port);
len += KSZ9477_PTP_TAG_LEN;
+ }

return ksz_common_rcv(skb, dev, port, len);
}
@@ -257,10 +278,11 @@ MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ9893);
* 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)
*/
@@ -304,7 +326,7 @@ static const struct dsa_device_ops lan937x_netdev_ops = {
.rcv = ksz9477_rcv,
.connect = ksz_connect,
.disconnect = ksz_disconnect,
- .needed_tailroom = LAN937X_EGRESS_TAG_LEN,
+ .needed_tailroom = LAN937X_EGRESS_TAG_LEN + KSZ9477_PTP_TAG_LEN,
};

DSA_TAG_DRIVER(lan937x_netdev_ops);
--
2.36.1
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