[PATCH v2 0/2] Add missing facility check to ptp_s390 driver

[PATCH v2 0/2] Add missing facility check to ptp_s390 driver

[Sven Schnelle]

This patchset adds a missing facility check and a check that the 'query
physical clock' (PTFF QPT) function is actually available. If it's not
present, no qpt ptp device will be registered. In order to use ptff_query()
in a module, the first patch adds a EXPORT_SYMBOL() to export
ptff_function_mask.

Changes in v2:
- drop CC check
- add PTFF QAF check
- add patch to export ptff_function_mask

Sven Schnelle (2):
  s390/ptff: Export ptff_function_mask[]
  ptp: ptp_s390: Add missing facility check

 arch/s390/kernel/time.c | 1 +
 drivers/ptp/ptp_s390.c  | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

--
2.55.0

[PATCH v2 1/2] s390/ptff: Export ptff_function_mask[]

[Sven Schnelle]

Export the ptff_function_mask to make ptff_query() usable in modules.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
---
 arch/s390/kernel/time.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index bd0df61d1907..2b989bebd220 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -65,6 +65,7 @@ ATOMIC_NOTIFIER_HEAD(s390_epoch_delta_notifier);
 EXPORT_SYMBOL(s390_epoch_delta_notifier);
 
 unsigned char ptff_function_mask[16];
+EXPORT_SYMBOL(ptff_function_mask);
 
 static unsigned long lpar_offset;
 static unsigned long initial_leap_seconds;
-- 
2.55.0

Re: [PATCH v2 1/2] s390/ptff: Export ptff_function_mask[]

[Heiko Carstens]

On Tue, Jul 14, 2026 at 03:03:41PM +0200, Sven Schnelle wrote:
> Export the ptff_function_mask to make ptff_query() usable in modules.
> 
> Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
> ---
>  arch/s390/kernel/time.c | 1 +
>  1 file changed, 1 insertion(+)

Acked-by: Heiko Carstens <hca@linux.ibm.com>

[PATCH v2 2/2] ptp: ptp_s390: Add missing facility check

[Sven Schnelle]

Only register the physical clock when facility 28 is installed
and PTFF QAF returns that PTFF QPT is available.

Fixes: 2d7de7a3010d ("s390/time: Add PtP driver")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Cc: stable@kernel.org
---
 drivers/ptp/ptp_s390.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/ptp/ptp_s390.c b/drivers/ptp/ptp_s390.c
index 29618eb9bf44..02d624d89a0a 100644
--- a/drivers/ptp/ptp_s390.c
+++ b/drivers/ptp/ptp_s390.c
@@ -107,6 +107,9 @@ static __init int ptp_s390_init(void)
 	if (IS_ERR(ptp_stcke_clock))
 		return PTR_ERR(ptp_stcke_clock);
 
+	if (!test_facility(28) || !ptff_query(PTFF_QPT))
+		return 0;
+
 	ptp_qpt_clock = ptp_clock_register(&ptp_s390_qpt_info, NULL);
 	if (IS_ERR(ptp_qpt_clock)) {
 		ptp_clock_unregister(ptp_stcke_clock);
@@ -117,7 +120,8 @@ static __init int ptp_s390_init(void)
 
 static __exit void ptp_s390_exit(void)
 {
-	ptp_clock_unregister(ptp_qpt_clock);
+	if (ptp_qpt_clock)
+		ptp_clock_unregister(ptp_qpt_clock);
 	ptp_clock_unregister(ptp_stcke_clock);
 }
 
-- 
2.55.0

Re: [PATCH v2 2/2] ptp: ptp_s390: Add missing facility check

[Heiko Carstens]

On Tue, Jul 14, 2026 at 03:03:42PM +0200, Sven Schnelle wrote:
> Only register the physical clock when facility 28 is installed
> and PTFF QAF returns that PTFF QPT is available.
> 
> Fixes: 2d7de7a3010d ("s390/time: Add PtP driver")
> Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
> Cc: stable@kernel.org
> ---
>  drivers/ptp/ptp_s390.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>