Emulate PTP_SYS_OFFSET by using an arithmetic mean of the
realtime samples from ->getcrosststamp callback.
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
---
drivers/ptp/ptp_chardev.c | 6 ++
include/linux/ptp_clock_kernel.h | 5 ++
include/linux/timekeeping_ptp.h | 10 ++++
kernel/time/timekeeping.c | 79 +++++++++++++++++++++++++++++++++++++++
4 files changed, 100 insertions(+)
Index: kvm-ptpdriver/drivers/ptp/ptp_chardev.c
===================================================================
--- kvm-ptpdriver.orig/drivers/ptp/ptp_chardev.c 2017-01-19 15:34:52.181338789 -0200
+++ kvm-ptpdriver/drivers/ptp/ptp_chardev.c 2017-01-19 15:35:31.705421911 -0200
@@ -23,6 +23,7 @@
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/timekeeping.h>
+#include <linux/timekeeping_ptp.h>
#include "ptp_private.h"
@@ -219,6 +220,11 @@
err = -EINVAL;
break;
}
+
+ if (ptp->info->emulate_ptp_sys_offset_mean) {
+ err = emulate_ptp_sys_offset(ptp->info, sysoff, arg);
+ break;
+ }
pct = &sysoff->ts[0];
for (i = 0; i < sysoff->n_samples; i++) {
getnstimeofday64(&ts);
Index: kvm-ptpdriver/include/linux/ptp_clock_kernel.h
===================================================================
--- kvm-ptpdriver.orig/include/linux/ptp_clock_kernel.h 2017-01-19 15:34:52.181338789 -0200
+++ kvm-ptpdriver/include/linux/ptp_clock_kernel.h 2017-01-19 15:35:31.706421913 -0200
@@ -99,6 +99,10 @@
* parameter func: the desired function to use.
* parameter chan: the function channel index to use.
*
+ * @emulate_ptp_sys_offset_mean: Emulate PTP_SYS_OFFSET ioctl
+ * using arithmetic mean of series of PTP_SYS_OFFSET_PRECISE
+ * ioctl.
+ *
* Drivers should embed their ptp_clock_info within a private
* structure, obtaining a reference to it using container_of().
*
@@ -115,6 +119,7 @@
int n_pins;
int pps;
struct ptp_pin_desc *pin_config;
+ bool emulate_ptp_sys_offset_mean;
int (*adjfine)(struct ptp_clock_info *ptp, long scaled_ppm);
int (*adjfreq)(struct ptp_clock_info *ptp, s32 delta);
int (*adjtime)(struct ptp_clock_info *ptp, s64 delta);
Index: kvm-ptpdriver/include/linux/timekeeping_ptp.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ kvm-ptpdriver/include/linux/timekeeping_ptp.h 2017-01-19 15:35:31.706421913 -0200
@@ -0,0 +1,10 @@
+#ifndef _LINUX_TIMEKEEPING_PTP_H
+#define _LINUX_TIMEKEEPING_PTP_H
+
+#include <uapi/linux/ptp_clock.h>
+#include <linux/ptp_clock_kernel.h>
+
+extern int emulate_ptp_sys_offset(struct ptp_clock_info *info,
+ struct ptp_sys_offset *sysoff,
+ unsigned long arg);
+#endif
Index: kvm-ptpdriver/kernel/time/timekeeping.c
===================================================================
--- kvm-ptpdriver.orig/kernel/time/timekeeping.c 2017-01-19 15:34:52.181338789 -0200
+++ kvm-ptpdriver/kernel/time/timekeeping.c 2017-01-20 09:29:13.978434149 -0200
@@ -23,6 +23,10 @@
#include <linux/stop_machine.h>
#include <linux/pvclock_gtod.h>
#include <linux/compiler.h>
+#include <linux/timekeeping_ptp.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
#include "tick-internal.h"
#include "ntp_internal.h"
@@ -1168,6 +1172,81 @@
}
EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
+static void mean_sys_realtime(struct system_device_crosststamp *xtstamp,
+ struct system_device_crosststamp *n_xtstamp,
+ struct ptp_clock_time *pct)
+{
+ ktime_t sys_realtime, n_sys_realtime;
+ struct timespec ts;
+ u64 ns;
+
+ /* estimate realtime with arithmetic mean of two crosststamp samples */
+ sys_realtime = xtstamp->sys_realtime;
+ n_sys_realtime = n_xtstamp->sys_realtime;
+ ns = ktime_divns(ktime_add(sys_realtime, n_sys_realtime), 2);
+ ts = ktime_to_timespec(ns_to_ktime(ns));
+ pct->sec = ts.tv_sec;
+ pct->nsec = ts.tv_nsec;
+}
+
+int emulate_ptp_sys_offset(struct ptp_clock_info *info,
+ struct ptp_sys_offset *sysoff,
+ unsigned long arg)
+{
+ unsigned long flags;
+ int i, err, len;
+ int n_samples;
+ struct system_device_crosststamp *xtstamps, *xtstamp, *n_xtstamp;
+ struct ptp_clock_time *pct;
+
+ n_samples = sysoff->n_samples + 2;
+
+ len = sizeof(struct system_device_crosststamp);
+ xtstamps = kzalloc(len * n_samples, GFP_KERNEL);
+ if (xtstamps == NULL)
+ return -ENOMEM;
+
+ /* stop update_wall_time, settimeofday */
+ raw_spin_lock_irqsave(&timekeeper_lock, flags);
+
+ xtstamp = xtstamps;
+ for (i = 0; i < n_samples; i++) {
+ err = info->getcrosststamp(info, xtstamp);
+ if (err) {
+ kfree(xtstamps);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+ return err;
+ }
+ xtstamp++;
+ }
+
+ pct = &sysoff->ts[0];
+ xtstamp = n_xtstamp = xtstamps;
+ n_xtstamp++;
+ for (i = 0; i < sysoff->n_samples; i++) {
+ struct timespec ts;
+
+ mean_sys_realtime(xtstamp, n_xtstamp, pct);
+ pct++;
+
+ ts = ktime_to_timespec(n_xtstamp->device);
+ pct->sec = ts.tv_sec;
+ pct->nsec = ts.tv_nsec;
+ pct++;
+ xtstamp++;
+ n_xtstamp++;
+ }
+
+ mean_sys_realtime(xtstamp, n_xtstamp, pct);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+ kfree(xtstamps);
+ if (copy_to_user((void __user *)arg, sysoff, sizeof(*sysoff)))
+ return -EFAULT;
+
+ return 0;
+}
+EXPORT_SYMBOL(emulate_ptp_sys_offset);
+
/**
* do_gettimeofday - Returns the time of day in a timeval
* @tv: pointer to the timeval to be set
--
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