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Subject[net-next, v5, 01/11] ptp: add ptp virtual clock driver framework
Date
This patch is to add ptp virtual clock driver framework
utilizing timecounter/cyclecounter.

The patch just exports two essential APIs for PTP driver.

- ptp_vclock_register()
- ptp_vclock_unregister()

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
---
Changes for v2:
- Split from v1 patch #1.
- Fixed build warning.
- Updated copyright.
Changes for v3:
- Supported PTP virtual clock in default in PTP driver.
Changes for v4:
- Renamed some MACROs.
- Used do_aux_work callback for vclock refreshing instead.
- Other minor fixes.
Changes for v5:
- None.
---
drivers/ptp/Makefile | 2 +-
drivers/ptp/ptp_private.h | 15 ++++
drivers/ptp/ptp_vclock.c | 150 +++++++++++++++++++++++++++++++
include/linux/ptp_clock_kernel.h | 4 +-
4 files changed, 169 insertions(+), 2 deletions(-)
create mode 100644 drivers/ptp/ptp_vclock.c

diff --git a/drivers/ptp/Makefile b/drivers/ptp/Makefile
index 8673d1743faa..28a6fe342d3e 100644
--- a/drivers/ptp/Makefile
+++ b/drivers/ptp/Makefile
@@ -3,7 +3,7 @@
# Makefile for PTP 1588 clock support.
#

-ptp-y := ptp_clock.o ptp_chardev.o ptp_sysfs.o
+ptp-y := ptp_clock.o ptp_chardev.o ptp_sysfs.o ptp_vclock.o
ptp_kvm-$(CONFIG_X86) := ptp_kvm_x86.o ptp_kvm_common.o
ptp_kvm-$(CONFIG_HAVE_ARM_SMCCC) := ptp_kvm_arm.o ptp_kvm_common.o
obj-$(CONFIG_PTP_1588_CLOCK) += ptp.o
diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
index 6b97155148f1..853b79b6b30e 100644
--- a/drivers/ptp/ptp_private.h
+++ b/drivers/ptp/ptp_private.h
@@ -48,6 +48,19 @@ struct ptp_clock {
struct kthread_delayed_work aux_work;
};

+#define info_to_vclock(d) container_of((d), struct ptp_vclock, info)
+#define cc_to_vclock(d) container_of((d), struct ptp_vclock, cc)
+#define dw_to_vclock(d) container_of((d), struct ptp_vclock, refresh_work)
+
+struct ptp_vclock {
+ struct ptp_clock *pclock;
+ struct ptp_clock_info info;
+ struct ptp_clock *clock;
+ struct cyclecounter cc;
+ struct timecounter tc;
+ spinlock_t lock; /* protects tc/cc */
+};
+
/*
* The function queue_cnt() is safe for readers to call without
* holding q->lock. Readers use this function to verify that the queue
@@ -89,4 +102,6 @@ extern const struct attribute_group *ptp_groups[];
int ptp_populate_pin_groups(struct ptp_clock *ptp);
void ptp_cleanup_pin_groups(struct ptp_clock *ptp);

+struct ptp_vclock *ptp_vclock_register(struct ptp_clock *pclock);
+void ptp_vclock_unregister(struct ptp_vclock *vclock);
#endif
diff --git a/drivers/ptp/ptp_vclock.c b/drivers/ptp/ptp_vclock.c
new file mode 100644
index 000000000000..fc9205cc504d
--- /dev/null
+++ b/drivers/ptp/ptp_vclock.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * PTP virtual clock driver
+ *
+ * Copyright 2021 NXP
+ */
+#include <linux/slab.h>
+#include "ptp_private.h"
+
+#define PTP_VCLOCK_CC_SHIFT 31
+#define PTP_VCLOCK_CC_MULT (1 << PTP_VCLOCK_CC_SHIFT)
+#define PTP_VCLOCK_FADJ_SHIFT 9
+#define PTP_VCLOCK_FADJ_DENOMINATOR 15625ULL
+#define PTP_VCLOCK_REFRESH_INTERVAL (HZ * 2)
+
+static int ptp_vclock_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
+{
+ struct ptp_vclock *vclock = info_to_vclock(ptp);
+ unsigned long flags;
+ s64 adj;
+
+ adj = (s64)scaled_ppm << PTP_VCLOCK_FADJ_SHIFT;
+ adj = div_s64(adj, PTP_VCLOCK_FADJ_DENOMINATOR);
+
+ spin_lock_irqsave(&vclock->lock, flags);
+ timecounter_read(&vclock->tc);
+ vclock->cc.mult = PTP_VCLOCK_CC_MULT + adj;
+ spin_unlock_irqrestore(&vclock->lock, flags);
+
+ return 0;
+}
+
+static int ptp_vclock_adjtime(struct ptp_clock_info *ptp, s64 delta)
+{
+ struct ptp_vclock *vclock = info_to_vclock(ptp);
+ unsigned long flags;
+
+ spin_lock_irqsave(&vclock->lock, flags);
+ timecounter_adjtime(&vclock->tc, delta);
+ spin_unlock_irqrestore(&vclock->lock, flags);
+
+ return 0;
+}
+
+static int ptp_vclock_gettime(struct ptp_clock_info *ptp,
+ struct timespec64 *ts)
+{
+ struct ptp_vclock *vclock = info_to_vclock(ptp);
+ unsigned long flags;
+ u64 ns;
+
+ spin_lock_irqsave(&vclock->lock, flags);
+ ns = timecounter_read(&vclock->tc);
+ spin_unlock_irqrestore(&vclock->lock, flags);
+ *ts = ns_to_timespec64(ns);
+
+ return 0;
+}
+
+static int ptp_vclock_settime(struct ptp_clock_info *ptp,
+ const struct timespec64 *ts)
+{
+ struct ptp_vclock *vclock = info_to_vclock(ptp);
+ u64 ns = timespec64_to_ns(ts);
+ unsigned long flags;
+
+ spin_lock_irqsave(&vclock->lock, flags);
+ timecounter_init(&vclock->tc, &vclock->cc, ns);
+ spin_unlock_irqrestore(&vclock->lock, flags);
+
+ return 0;
+}
+
+static long ptp_vclock_refresh(struct ptp_clock_info *ptp)
+{
+ struct ptp_vclock *vclock = info_to_vclock(ptp);
+ struct timespec64 ts;
+
+ ptp_vclock_gettime(&vclock->info, &ts);
+
+ return PTP_VCLOCK_REFRESH_INTERVAL;
+}
+
+static const struct ptp_clock_info ptp_vclock_info = {
+ .owner = THIS_MODULE,
+ .name = "ptp virtual clock",
+ /* The maximum ppb value that long scaled_ppm can support */
+ .max_adj = 32767999,
+ .adjfine = ptp_vclock_adjfine,
+ .adjtime = ptp_vclock_adjtime,
+ .gettime64 = ptp_vclock_gettime,
+ .settime64 = ptp_vclock_settime,
+ .do_aux_work = ptp_vclock_refresh,
+};
+
+static u64 ptp_vclock_read(const struct cyclecounter *cc)
+{
+ struct ptp_vclock *vclock = cc_to_vclock(cc);
+ struct ptp_clock *ptp = vclock->pclock;
+ struct timespec64 ts = {};
+
+ if (ptp->info->gettimex64)
+ ptp->info->gettimex64(ptp->info, &ts, NULL);
+ else
+ ptp->info->gettime64(ptp->info, &ts);
+
+ return timespec64_to_ns(&ts);
+}
+
+static const struct cyclecounter ptp_vclock_cc = {
+ .read = ptp_vclock_read,
+ .mask = CYCLECOUNTER_MASK(32),
+ .mult = PTP_VCLOCK_CC_MULT,
+ .shift = PTP_VCLOCK_CC_SHIFT,
+};
+
+struct ptp_vclock *ptp_vclock_register(struct ptp_clock *pclock)
+{
+ struct ptp_vclock *vclock;
+
+ vclock = kzalloc(sizeof(*vclock), GFP_KERNEL);
+ if (!vclock)
+ return NULL;
+
+ vclock->pclock = pclock;
+ vclock->info = ptp_vclock_info;
+ vclock->cc = ptp_vclock_cc;
+
+ snprintf(vclock->info.name, PTP_CLOCK_NAME_LEN, "ptp%d_virt",
+ pclock->index);
+
+ spin_lock_init(&vclock->lock);
+
+ vclock->clock = ptp_clock_register(&vclock->info, &pclock->dev);
+ if (IS_ERR_OR_NULL(vclock->clock)) {
+ kfree(vclock);
+ return NULL;
+ }
+
+ timecounter_init(&vclock->tc, &vclock->cc, 0);
+ ptp_schedule_worker(vclock->clock, PTP_VCLOCK_REFRESH_INTERVAL);
+
+ return vclock;
+}
+
+void ptp_vclock_unregister(struct ptp_vclock *vclock)
+{
+ ptp_clock_unregister(vclock->clock);
+ kfree(vclock);
+}
diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
index aba237c0b3a2..b6fb771ee524 100644
--- a/include/linux/ptp_clock_kernel.h
+++ b/include/linux/ptp_clock_kernel.h
@@ -11,7 +11,9 @@
#include <linux/device.h>
#include <linux/pps_kernel.h>
#include <linux/ptp_clock.h>
+#include <linux/timecounter.h>

+#define PTP_CLOCK_NAME_LEN 32
/**
* struct ptp_clock_request - request PTP clock event
*
@@ -134,7 +136,7 @@ struct ptp_system_timestamp {

struct ptp_clock_info {
struct module *owner;
- char name[16];
+ char name[PTP_CLOCK_NAME_LEN];
s32 max_adj;
int n_alarm;
int n_ext_ts;
--
2.25.1
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