net: mscc: ocelot: deny TX timestamping of non-PTP packets

It appears that Ocelot switches cannot timestamp non-PTP frames,
I tested this using the isochron program at:
https://github.com/vladimiroltean/tsn-scripts

with the result that the driver increments the ocelot_port->ts_id
counter as expected, puts it in the REW_OP, but the hardware seems to
not timestamp these packets at all, since no IRQ is emitted.

Therefore check whether we are sending PTP frames, and refuse to
populate REW_OP otherwise.

Fixes: 4e3b0468e6d7 ("net: mscc: PTP Hardware Clock (PHC) support")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c
index 687c07c..3b1f0bb 100644 (file)
--- a/drivers/net/ethernet/mscc/ocelot.c
+++ b/drivers/net/ethernet/mscc/ocelot.c
@@ -618,16 +618,12 @@ u32 ocelot_ptp_rew_op(struct sk_buff *skb)
 }
 EXPORT_SYMBOL(ocelot_ptp_rew_op);
 
-static bool ocelot_ptp_is_onestep_sync(struct sk_buff *skb)
+static bool ocelot_ptp_is_onestep_sync(struct sk_buff *skb,
+                                      unsigned int ptp_class)
 {
        struct ptp_header *hdr;
-       unsigned int ptp_class;
        u8 msgtype, twostep;
 
-       ptp_class = ptp_classify_raw(skb);
-       if (ptp_class == PTP_CLASS_NONE)
-               return false;
-
        hdr = ptp_parse_header(skb, ptp_class);
        if (!hdr)
                return false;
@@ -647,11 +643,20 @@ int ocelot_port_txtstamp_request(struct ocelot *ocelot, int port,
 {
        struct ocelot_port *ocelot_port = ocelot->ports[port];
        u8 ptp_cmd = ocelot_port->ptp_cmd;
+       unsigned int ptp_class;
        int err;
 
+       /* Don't do anything if PTP timestamping not enabled */
+       if (!ptp_cmd)
+               return 0;
+
+       ptp_class = ptp_classify_raw(skb);
+       if (ptp_class == PTP_CLASS_NONE)
+               return -EINVAL;
+
        /* Store ptp_cmd in OCELOT_SKB_CB(skb)->ptp_cmd */
        if (ptp_cmd == IFH_REW_OP_ORIGIN_PTP) {
-               if (ocelot_ptp_is_onestep_sync(skb)) {
+               if (ocelot_ptp_is_onestep_sync(skb, ptp_class)) {
                        OCELOT_SKB_CB(skb)->ptp_cmd = ptp_cmd;
                        return 0;
                }