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From: Jacob Keller <jacob.e.keller@intel.com>
Date: Thu, 14 Nov 2019 10:44:57 -0800
Subject: mv88e6xxx: reject unsupported external timestamp flags
Patch-mainline: v5.4-rc8
Git-commit: 7d9465ebcc5d0e5ab0d7dd36d7147d31cc76fcaf
References: jsc#SLE-13536

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.

For the record, the semantics of this driver are:

  flags                                                 Meaning
  ----------------------------------------------------  --------------------------
  PTP_ENABLE_FEATURE                                    Time stamp falling edge
  PTP_ENABLE_FEATURE|PTP_RISING_EDGE                    Time stamp rising edge
  PTP_ENABLE_FEATURE|PTP_FALLING_EDGE                   Time stamp falling edge
  PTP_ENABLE_FEATURE|PTP_RISING_EDGE|PTP_FALLING_EDGE   Time stamp rising edge

Cc: Brandon Streiff <brandon.streiff@ni.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/dsa/mv88e6xxx/ptp.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/net/dsa/mv88e6xxx/ptp.c
+++ b/drivers/net/dsa/mv88e6xxx/ptp.c
@@ -273,6 +273,12 @@ static int mv88e6352_ptp_enable_extts(st
 	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)