ptp: add ptp virtual clock driver framework

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>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/ptp/Makefile b/drivers/ptp/Makefile
index 8673d17..28a6fe3 100644 (file)
--- 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 6b97155..853b79b 100644 (file)
--- 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 (file)
index 0000000..fc9205c
--- /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 aba237c..b6fb771 100644 (file)
--- 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;