net: mvpp2: ptp: add support for receive timestamping

Add support for receive timestamping. When enabled, the hardware adds
a timestamp into the receive queue descriptor for all received packets
with no filtering. Hence, we can only support NONE or ALL receive
filter modes.

The timestamp in the receive queue contains two bit sof seconds and
the full nanosecond timestamp. This has to be merged with the remainder
of the seconds from the TAI clock to arrive at a full timestamp before
we can convert it to a ktime for the skb hardware timestamp field.

Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 57 insertions, 0 deletions

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
index 86c94ca97e43..95862aff49f1 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
@@ -59,6 +59,8 @@ struct mvpp2_tai {
 	void __iomem *base;
 	spinlock_t lock;
 	u64 period;		// nanosecond period in 32.32 fixed point
+	/* This timestamp is updated every two seconds */
+	struct timespec64 stamp;
 };
 
 static void mvpp2_tai_modify(void __iomem *reg, u32 mask, u32 set)
@@ -297,6 +299,15 @@ static int mvpp22_tai_settime64(struct ptp_clock_info *ptp,
 	return 0;
 }
 
+static long mvpp22_tai_aux_work(struct ptp_clock_info *ptp)
+{
+	struct mvpp2_tai *tai = ptp_to_tai(ptp);
+
+	mvpp22_tai_gettimex64(ptp, &tai->stamp, NULL);
+
+	return msecs_to_jiffies(2000);
+}
+
 static void mvpp22_tai_set_step(struct mvpp2_tai *tai)
 {
 	void __iomem *base = tai->base;
@@ -326,6 +337,51 @@ static void mvpp22_tai_init(struct mvpp2_tai *tai)
 	mvpp2_tai_modify(base + MVPP22_TAI_CR0, CR0_SW_NRESET, CR0_SW_NRESET);
 }
 
+int mvpp22_tai_ptp_clock_index(struct mvpp2_tai *tai)
+{
+	return ptp_clock_index(tai->ptp_clock);
+}
+
+void mvpp22_tai_tstamp(struct mvpp2_tai *tai, u32 tstamp,
+		       struct skb_shared_hwtstamps *hwtstamp)
+{
+	struct timespec64 ts;
+	int delta;
+
+	/* The tstamp consists of 2 bits of seconds and 30 bits of nanoseconds.
+	 * We use our stored timestamp (tai->stamp) to form a full timestamp,
+	 * and we must read the seconds exactly once.
+	 */
+	ts.tv_sec = READ_ONCE(tai->stamp.tv_sec);
+	ts.tv_nsec = tstamp & 0x3fffffff;
+
+	/* Calculate the delta in seconds between our stored timestamp and
+	 * the value read from the queue. Allow timestamps one second in the
+	 * past, otherwise consider them to be in the future.
+	 */
+	delta = ((tstamp >> 30) - (ts.tv_sec & 3)) & 3;
+	if (delta == 3)
+		delta -= 4;
+	ts.tv_sec += delta;
+
+	memset(hwtstamp, 0, sizeof(*hwtstamp));
+	hwtstamp->hwtstamp = timespec64_to_ktime(ts);
+}
+
+void mvpp22_tai_start(struct mvpp2_tai *tai)
+{
+	long delay;
+
+	delay = mvpp22_tai_aux_work(&tai->caps);
+
+	ptp_schedule_worker(tai->ptp_clock, delay);
+}
+
+void mvpp22_tai_stop(struct mvpp2_tai *tai)
+{
+	ptp_cancel_worker_sync(tai->ptp_clock);
+}
+
 static void mvpp22_tai_remove(void *priv)
 {
 	struct mvpp2_tai *tai = priv;
@@ -385,6 +441,7 @@ int mvpp22_tai_probe(struct device *dev, struct mvpp2 *priv)
 	tai->caps.adjtime = mvpp22_tai_adjtime;
 	tai->caps.gettimex64 = mvpp22_tai_gettimex64;
 	tai->caps.settime64 = mvpp22_tai_settime64;
+	tai->caps.do_aux_work = mvpp22_tai_aux_work;
 
 	ret = devm_add_action(dev, mvpp22_tai_remove, tai);
 	if (ret)