[net-next v3 3/7] mv88e6xxx: reject unsupported external timestamp flags

[Jacob Keller]

Fix the mv88e6xxx PTP support to explicitly reject any future flags that
get added to the external timestamp request ioctl.

In order to maintain currently functioning code, this patch accepts all
three current flags. This is because the PTP_RISING_EDGE and
PTP_FALLING_EDGE flags have unclear semantics and each driver seems to
have interpreted them slightly differently.

Cc: Brandon Streiff <brandon.stre...@ni.com>
Signed-off-by: Jacob Keller <jacob.e.kel...@intel.com>
---
 drivers/net/dsa/mv88e6xxx/ptp.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/dsa/mv88e6xxx/ptp.c b/drivers/net/dsa/mv88e6xxx/ptp.c
index 073cbd0bb91b..076e622a64d6 100644
--- a/drivers/net/dsa/mv88e6xxx/ptp.c
+++ b/drivers/net/dsa/mv88e6xxx/ptp.c
@@ -273,6 +273,12 @@ static int mv88e6352_ptp_enable_extts(struct 
mv88e6xxx_chip *chip,
        int pin;
        int err;
 
+       /* Reject requests with unsupported flags */
+       if (rq->extts.flags & ~(PTP_ENABLE_FEATURE |
+                               PTP_RISING_EDGE |
+                               PTP_FALLING_EDGE))
+               return -EOPNOTSUPP;
+
        pin = ptp_find_pin(chip->ptp_clock, PTP_PF_EXTTS, rq->extts.index);
 
        if (pin < 0)
-- 
2.23.0.245.gf157bbb9169d