Merge branch 'ptp-driver-for-s390-clocks'

Sven Schnelle says:

====================
PtP driver for s390 clocks

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.
====================

Link: https://patch.msgid.link/20241023065601.449586-1-svens@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

MAINTAINERS

@@ -20204,6 +20204,12 @@ 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

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 */

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

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)
@@ -468,6 +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);

drivers/ptp/Kconfig

@@ -237,4 +237,15 @@ 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

drivers/ptp/Makefile

@@ -22,3 +22,4 @@ 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

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");

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,