3 files changed, 77 insertions, 2 deletions

diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c
index b7d51e4ec792..336d93d03a9a 100644
--- a/drivers/net/dsa/ocelot/felix.c
+++ b/drivers/net/dsa/ocelot/felix.c
@@ -16,6 +16,7 @@
 #include <linux/dsa/8021q.h>
 #include <linux/dsa/ocelot.h>
 #include <linux/platform_device.h>
+#include <linux/ptp_classify.h>
 #include <linux/module.h>
 #include <linux/of_net.h>
 #include <linux/pci.h>
@@ -345,6 +346,15 @@ static int felix_setup_mmio_filtering(struct felix *felix)
 		return ret;
 	}
 
+	/* The ownership of the CPU port module's queues might have just been
+	 * transferred to the tag_8021q tagger from the NPI-based tagger.
+	 * So there might still be all sorts of crap in the queues. On the
+	 * other hand, the MMIO-based matching of PTP frames is very brittle,
+	 * so we need to be careful that there are no extra frames to be
+	 * dequeued over MMIO, since we would never know to discard them.
+	 */
+	ocelot_drain_cpu_queue(ocelot, 0);
+
 	return 0;
 }
 
@@ -1273,6 +1283,55 @@ static int felix_hwtstamp_set(struct dsa_switch *ds, int port,
 	return ocelot_hwstamp_set(ocelot, port, ifr);
 }
 
+static bool felix_check_xtr_pkt(struct ocelot *ocelot, unsigned int ptp_type)
+{
+	struct felix *felix = ocelot_to_felix(ocelot);
+	int err, grp = 0;
+
+	if (felix->tag_proto != DSA_TAG_PROTO_OCELOT_8021Q)
+		return false;
+
+	if (!felix->info->quirk_no_xtr_irq)
+		return false;
+
+	if (ptp_type == PTP_CLASS_NONE)
+		return false;
+
+	while (ocelot_read(ocelot, QS_XTR_DATA_PRESENT) & BIT(grp)) {
+		struct sk_buff *skb;
+		unsigned int type;
+
+		err = ocelot_xtr_poll_frame(ocelot, grp, &skb);
+		if (err)
+			goto out;
+
+		/* We trap to the CPU port module all PTP frames, but
+		 * felix_rxtstamp() only gets called for event frames.
+		 * So we need to avoid sending duplicate general
+		 * message frames by running a second BPF classifier
+		 * here and dropping those.
+		 */
+		__skb_push(skb, ETH_HLEN);
+
+		type = ptp_classify_raw(skb);
+
+		__skb_pull(skb, ETH_HLEN);
+
+		if (type == PTP_CLASS_NONE) {
+			kfree_skb(skb);
+			continue;
+		}
+
+		netif_rx(skb);
+	}
+
+out:
+	if (err < 0)
+		ocelot_drain_cpu_queue(ocelot, 0);
+
+	return true;
+}
+
 static bool felix_rxtstamp(struct dsa_switch *ds, int port,
 			   struct sk_buff *skb, unsigned int type)
 {
@@ -1283,6 +1342,16 @@ static bool felix_rxtstamp(struct dsa_switch *ds, int port,
 	struct timespec64 ts;
 	u64 tstamp, val;
 
+	/* If the "no XTR IRQ" workaround is in use, tell DSA to defer this skb
+	 * for RX timestamping. Then free it, and poll for its copy through
+	 * MMIO in the CPU port module, and inject that into the stack from
+	 * ocelot_xtr_poll().
+	 */
+	if (felix_check_xtr_pkt(ocelot, type)) {
+		kfree_skb(skb);
+		return true;
+	}
+
 	ocelot_ptp_gettime64(&ocelot->ptp_info, &ts);
 	tstamp = ktime_set(ts.tv_sec, ts.tv_nsec);
 
diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c
index 981811ffcdae..8d97c731e953 100644
--- a/drivers/net/ethernet/mscc/ocelot.c
+++ b/drivers/net/ethernet/mscc/ocelot.c
@@ -837,6 +837,13 @@ void ocelot_port_inject_frame(struct ocelot *ocelot, int port, int grp,
 }
 EXPORT_SYMBOL(ocelot_port_inject_frame);
 
+void ocelot_drain_cpu_queue(struct ocelot *ocelot, int grp)
+{
+	while (ocelot_read(ocelot, QS_XTR_DATA_PRESENT) & BIT(grp))
+		ocelot_read_rix(ocelot, QS_XTR_RD, grp);
+}
+EXPORT_SYMBOL(ocelot_drain_cpu_queue);
+
 int ocelot_fdb_add(struct ocelot *ocelot, int port,
 		   const unsigned char *addr, u16 vid)
 {
diff --git a/drivers/net/ethernet/mscc/ocelot_vsc7514.c b/drivers/net/ethernet/mscc/ocelot_vsc7514.c
index 47ee06832a51..4bd7e9d9ec61 100644
--- a/drivers/net/ethernet/mscc/ocelot_vsc7514.c
+++ b/drivers/net/ethernet/mscc/ocelot_vsc7514.c
@@ -552,8 +552,7 @@ static irqreturn_t ocelot_xtr_irq_handler(int irq, void *arg)
 
 out:
 	if (err < 0)
-		while (ocelot_read(ocelot, QS_XTR_DATA_PRESENT) & BIT(grp))
-			ocelot_read_rix(ocelot, QS_XTR_RD, grp);
+		ocelot_drain_cpu_queue(ocelot, 0);
 
 	return IRQ_HANDLED;
 }