[PATCH v3 0/2] PtP driver for s390 clocks

[PATCH v3 0/2] PtP driver for s390 clocks

[Sven Schnelle]

Hi,

these patches add support for using the s390 physical and TOD clock as ptp
clock. To do so, the first patch adds a clock id to the s390 TOD clock,
while the second patch adds the PtP driver itself.

Changes in v3:
- drop 'IBM' from clock names
- use u128 as return type of eitod_to_ns()
- fix calculation in eitod_to_timespec64()

Changes in v2:
- add missing MODULE_DESCRIPTION()
- drop udev event patch
- simplify eitod_to_ns()
- use store_tod_clock_ext() instead of store_tod_clock_ext_cc()
- move stp_enabled() declaration to stp.h
- use s390 instead of 'Z' in clock names
- defconfig symbol should be default-n

Sven Schnelle (2):
  s390/time: Add clocksource id to TOD clock
  s390/time: Add PtP driver

 MAINTAINERS                     |   6 ++
 arch/s390/include/asm/stp.h     |   1 +
 arch/s390/include/asm/timex.h   |   6 ++
 arch/s390/kernel/time.c         |   7 ++
 drivers/ptp/Kconfig             |  11 +++
 drivers/ptp/Makefile            |   1 +
 drivers/ptp/ptp_s390.c          | 129 ++++++++++++++++++++++++++++++++
 include/linux/clocksource_ids.h |   1 +
 8 files changed, 162 insertions(+)
 create mode 100644 drivers/ptp/ptp_s390.c

-- 
2.43.0

[PATCH v3 1/2] s390/time: Add clocksource id to TOD clock

[Sven Schnelle]

To allow specifying the clock source in the upcoming PtP driver,
add a clocksource ID to the s390 TOD clock.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
---
 arch/s390/kernel/time.c         | 1 +
 include/linux/clocksource_ids.h | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index b713effe0579..4214901c3ab0 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -255,6 +255,7 @@ static struct clocksource clocksource_tod = {
 	.shift		= 24,
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 	.vdso_clock_mode = VDSO_CLOCKMODE_TOD,
+	.id		= CSID_S390_TOD,
 };
 
 struct clocksource * __init clocksource_default_clock(void)
diff --git a/include/linux/clocksource_ids.h b/include/linux/clocksource_ids.h
index 2bb4d8c2f1b0..c4ef4ae2eded 100644
--- a/include/linux/clocksource_ids.h
+++ b/include/linux/clocksource_ids.h
@@ -6,6 +6,7 @@
 enum clocksource_ids {
 	CSID_GENERIC		= 0,
 	CSID_ARM_ARCH_COUNTER,
+	CSID_S390_TOD,
 	CSID_X86_TSC_EARLY,
 	CSID_X86_TSC,
 	CSID_X86_KVM_CLK,
-- 
2.43.0

[PATCH v3 2/2] s390/time: Add PtP driver

[Sven Schnelle]

Add a small PtP driver which allows user space to get
the values of the physical and tod clock. This allows
programs like chrony to use STP as clock source and
steer the kernel clock. The physical clock can be used
as a debugging aid to get the clock without any additional
offsets like STP steering or LPAR offset.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
---
 MAINTAINERS                   |   6 ++
 arch/s390/include/asm/stp.h   |   1 +
 arch/s390/include/asm/timex.h |   6 ++
 arch/s390/kernel/time.c       |   6 ++
 drivers/ptp/Kconfig           |  11 +++
 drivers/ptp/Makefile          |   1 +
 drivers/ptp/ptp_s390.c        | 129 ++++++++++++++++++++++++++++++++++
 7 files changed, 160 insertions(+)
 create mode 100644 drivers/ptp/ptp_s390.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 7ad507f49324..94793c935e86 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -20328,6 +20328,12 @@ F:	Documentation/arch/s390/pci.rst
 F:	arch/s390/pci/
 F:	drivers/pci/hotplug/s390_pci_hpc.c
 
+S390 PTP DRIVER
+M:	Sven Schnelle <svens@linux.ibm.com>
+L:	linux-s390@vger.kernel.org
+S:	Supported
+F:	drivers/ptp/ptp_s390.c
+
 S390 SCM DRIVER
 M:	Vineeth Vijayan <vneethv@linux.ibm.com>
 L:	linux-s390@vger.kernel.org
diff --git a/arch/s390/include/asm/stp.h b/arch/s390/include/asm/stp.h
index 4d74d7e33340..827cb208de86 100644
--- a/arch/s390/include/asm/stp.h
+++ b/arch/s390/include/asm/stp.h
@@ -94,5 +94,6 @@ struct stp_stzi {
 int stp_sync_check(void);
 int stp_island_check(void);
 void stp_queue_work(void);
+bool stp_enabled(void);
 
 #endif /* __S390_STP_H */
diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h
index 640901f2fbc3..642fd303ce01 100644
--- a/arch/s390/include/asm/timex.h
+++ b/arch/s390/include/asm/timex.h
@@ -93,6 +93,7 @@ extern unsigned char ptff_function_mask[16];
 #define PTFF_QAF	0x00	/* query available functions */
 #define PTFF_QTO	0x01	/* query tod offset */
 #define PTFF_QSI	0x02	/* query steering information */
+#define PTFF_QPT	0x03	/* query physical clock */
 #define PTFF_QUI	0x04	/* query UTC information */
 #define PTFF_ATO	0x40	/* adjust tod offset */
 #define PTFF_STO	0x41	/* set tod offset */
@@ -250,6 +251,11 @@ static __always_inline unsigned long tod_to_ns(unsigned long todval)
 	return ((todval >> 9) * 125) + (((todval & 0x1ff) * 125) >> 9);
 }
 
+static __always_inline u128 eitod_to_ns(u128 todval)
+{
+	return (todval * 125) >> 9;
+}
+
 /**
  * tod_after - compare two 64 bit TOD values
  * @a: first 64 bit TOD timestamp
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 4214901c3ab0..cc60b16a7dd0 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -469,6 +469,12 @@ static void __init stp_reset(void)
 	}
 }
 
+bool stp_enabled(void)
+{
+	return test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags) && stp_online;
+}
+EXPORT_SYMBOL(stp_enabled);
+
 static void stp_timeout(struct timer_list *unused)
 {
 	queue_work(time_sync_wq, &stp_work);
diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig
index 604541dcb320..8aaca40cab08 100644
--- a/drivers/ptp/Kconfig
+++ b/drivers/ptp/Kconfig
@@ -224,4 +224,15 @@ config PTP_DFL_TOD
 	  To compile this driver as a module, choose M here: the module
 	  will be called ptp_dfl_tod.
 
+config PTP_S390
+	tristate "S390 PTP driver"
+	depends on PTP_1588_CLOCK
+	depends on S390
+	help
+	  This driver adds support for S390 time steering via the PtP
+	  interface. This works by adding a in-kernel clock delta value,
+	  which is always added to time values used in the kernel. The PtP
+	  driver provides the raw clock value without the delta to
+	  userspace. That way userspace programs like chrony could steer
+	  the kernel clock.
 endmenu
diff --git a/drivers/ptp/Makefile b/drivers/ptp/Makefile
index 68bf02078053..4dd9f35eb0cf 100644
--- a/drivers/ptp/Makefile
+++ b/drivers/ptp/Makefile
@@ -21,3 +21,4 @@ obj-$(CONFIG_PTP_1588_CLOCK_MOCK)	+= ptp_mock.o
 obj-$(CONFIG_PTP_1588_CLOCK_VMW)	+= ptp_vmw.o
 obj-$(CONFIG_PTP_1588_CLOCK_OCP)	+= ptp_ocp.o
 obj-$(CONFIG_PTP_DFL_TOD)		+= ptp_dfl_tod.o
+obj-$(CONFIG_PTP_S390)			+= ptp_s390.o
diff --git a/drivers/ptp/ptp_s390.c b/drivers/ptp/ptp_s390.c
new file mode 100644
index 000000000000..6218983080f8
--- /dev/null
+++ b/drivers/ptp/ptp_s390.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * s390 PTP clock driver
+ *
+ */
+
+#include "ptp_private.h"
+#include <linux/time.h>
+#include <asm/stp.h>
+
+static struct ptp_clock *ptp_stcke_clock, *ptp_qpt_clock;
+
+static int ptp_s390_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
+{
+	return -EOPNOTSUPP;
+}
+
+static int ptp_s390_adjtime(struct ptp_clock_info *ptp, s64 delta)
+{
+	return -EOPNOTSUPP;
+}
+
+static struct timespec64 eitod_to_timespec64(union tod_clock *clk)
+{
+	return ns_to_timespec64(eitod_to_ns(clk->eitod - TOD_UNIX_EPOCH));
+}
+
+static struct timespec64 tod_to_timespec64(unsigned long tod)
+{
+	return ns_to_timespec64(tod_to_ns(tod - TOD_UNIX_EPOCH));
+}
+
+static int ptp_s390_stcke_gettime(struct ptp_clock_info *ptp,
+				  struct timespec64 *ts)
+{
+	union tod_clock tod;
+
+	if (!stp_enabled())
+		return -EOPNOTSUPP;
+
+	store_tod_clock_ext(&tod);
+	*ts = eitod_to_timespec64(&tod);
+	return 0;
+}
+
+static int ptp_s390_qpt_gettime(struct ptp_clock_info *ptp,
+				struct timespec64 *ts)
+{
+	unsigned long tod;
+
+	ptff(&tod, sizeof(tod), PTFF_QPT);
+	*ts = tod_to_timespec64(tod);
+	return 0;
+}
+
+static int ptp_s390_settime(struct ptp_clock_info *ptp,
+			    const struct timespec64 *ts)
+{
+	return -EOPNOTSUPP;
+}
+
+static int s390_arch_ptp_get_crosststamp(ktime_t *device_time,
+					 struct system_counterval_t *system_counter,
+					 void *ctx)
+{
+	union tod_clock clk;
+
+	store_tod_clock_ext(&clk);
+	*device_time = ns_to_ktime(tod_to_ns(clk.tod - TOD_UNIX_EPOCH));
+	system_counter->cycles = clk.tod;
+	system_counter->cs_id = CSID_S390_TOD;
+	return 0;
+}
+
+static int ptp_s390_getcrosststamp(struct ptp_clock_info *ptp,
+				   struct system_device_crosststamp *xtstamp)
+{
+	if (!stp_enabled())
+		return -EOPNOTSUPP;
+	return get_device_system_crosststamp(s390_arch_ptp_get_crosststamp, NULL, NULL, xtstamp);
+}
+
+static struct ptp_clock_info ptp_s390_stcke_info = {
+	.owner		= THIS_MODULE,
+	.name		= "s390 STCKE Clock",
+	.max_adj	= 0,
+	.adjfine	= ptp_s390_adjfine,
+	.adjtime	= ptp_s390_adjtime,
+	.gettime64	= ptp_s390_stcke_gettime,
+	.settime64	= ptp_s390_settime,
+	.getcrosststamp = ptp_s390_getcrosststamp,
+};
+
+static struct ptp_clock_info ptp_s390_qpt_info = {
+	.owner		= THIS_MODULE,
+	.name		= "s390 Physical Clock",
+	.max_adj	= 0,
+	.adjfine	= ptp_s390_adjfine,
+	.adjtime	= ptp_s390_adjtime,
+	.gettime64	= ptp_s390_qpt_gettime,
+	.settime64	= ptp_s390_settime,
+};
+
+static __init int ptp_s390_init(void)
+{
+	ptp_stcke_clock = ptp_clock_register(&ptp_s390_stcke_info, NULL);
+	if (IS_ERR(ptp_stcke_clock))
+		return PTR_ERR(ptp_stcke_clock);
+
+	ptp_qpt_clock = ptp_clock_register(&ptp_s390_qpt_info, NULL);
+	if (IS_ERR(ptp_qpt_clock)) {
+		ptp_clock_unregister(ptp_stcke_clock);
+		return PTR_ERR(ptp_qpt_clock);
+	}
+	return 0;
+}
+
+static __exit void ptp_s390_exit(void)
+{
+	ptp_clock_unregister(ptp_qpt_clock);
+	ptp_clock_unregister(ptp_stcke_clock);
+}
+
+module_init(ptp_s390_init);
+module_exit(ptp_s390_exit);
+
+MODULE_AUTHOR("Sven Schnelle <svens@linux.ibm.com>");
+MODULE_DESCRIPTION("s390 Physical/STCKE Clock PtP Driver");
+MODULE_LICENSE("GPL");
-- 
2.43.0

Re: [PATCH v3 0/2] PtP driver for s390 clocks

[Heiko Carstens]

On Thu, Oct 17, 2024 at 08:07:47AM +0200, Sven Schnelle wrote:
> Hi,
> 
> these patches add support for using the s390 physical and TOD clock as ptp
> clock. To do so, the first patch adds a clock id to the s390 TOD clock,
> while the second patch adds the PtP driver itself.
...
>  MAINTAINERS                     |   6 ++
>  arch/s390/include/asm/stp.h     |   1 +
>  arch/s390/include/asm/timex.h   |   6 ++
>  arch/s390/kernel/time.c         |   7 ++
>  drivers/ptp/Kconfig             |  11 +++
>  drivers/ptp/Makefile            |   1 +
>  drivers/ptp/ptp_s390.c          | 129 ++++++++++++++++++++++++++++++++
>  include/linux/clocksource_ids.h |   1 +
>  8 files changed, 162 insertions(+)
>  create mode 100644 drivers/ptp/ptp_s390.c

As far as I am concerned:
Acked-by: Heiko Carstens <hca@linux.ibm.com>

Richard, if this looks good for you too, how should this go upstream?
We could carry this via the s390 tree, if you want.

Re: [PATCH v3 0/2] PtP driver for s390 clocks

[Richard Cochran]

On Thu, Oct 17, 2024 at 11:46:06AM +0200, Heiko Carstens wrote:

> Richard, if this looks good for you too, how should this go upstream?
> We could carry this via the s390 tree, if you want.

PTP drivers normally go through net-next.

Thanks,
Richard

Re: [PATCH v3 0/2] PtP driver for s390 clocks

[Richard Cochran]

On Thu, Oct 17, 2024 at 08:07:47AM +0200, Sven Schnelle wrote:
> Hi,
> 
> these patches add support for using the s390 physical and TOD clock as ptp
> clock. To do so, the first patch adds a clock id to the s390 TOD clock,
> while the second patch adds the PtP driver itself.

For the series:

Acked-by: Richard Cochran <richardcochran@gmail.com>