From fcbb27b0ec6dcbc5a5108cb8fb19eae64593d204 Mon Sep 17 00:00:00 2001
From: Timothy Pearson <tpearson@raptorengineering.com>
Date: Wed, 23 Aug 2017 14:45:25 -0500
Subject: Initial import of modified Linux 2.6.28 tree

Original upstream URL:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git | branch linux-2.6.28.y
---
 kernel/time/tick-oneshot.c | 141 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 141 insertions(+)
 create mode 100644 kernel/time/tick-oneshot.c

(limited to 'kernel/time/tick-oneshot.c')

diff --git a/kernel/time/tick-oneshot.c b/kernel/time/tick-oneshot.c
new file mode 100644
index 0000000..2e8de67
--- /dev/null
+++ b/kernel/time/tick-oneshot.c
@@ -0,0 +1,141 @@
+/*
+ * linux/kernel/time/tick-oneshot.c
+ *
+ * This file contains functions which manage high resolution tick
+ * related events.
+ *
+ * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
+ * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
+ * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
+ *
+ * This code is licenced under the GPL version 2. For details see
+ * kernel-base/COPYING.
+ */
+#include <linux/cpu.h>
+#include <linux/err.h>
+#include <linux/hrtimer.h>
+#include <linux/interrupt.h>
+#include <linux/percpu.h>
+#include <linux/profile.h>
+#include <linux/sched.h>
+#include <linux/tick.h>
+
+#include "tick-internal.h"
+
+/**
+ * tick_program_event internal worker function
+ */
+int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
+			   int force)
+{
+	ktime_t now = ktime_get();
+	int i;
+
+	for (i = 0;;) {
+		int ret = clockevents_program_event(dev, expires, now);
+
+		if (!ret || !force)
+			return ret;
+
+		/*
+		 * We tried 2 times to program the device with the given
+		 * min_delta_ns. If that's not working then we double it
+		 * and emit a warning.
+		 */
+		if (++i > 2) {
+			/* Increase the min. delta and try again */
+			if (!dev->min_delta_ns)
+				dev->min_delta_ns = 5000;
+			else
+				dev->min_delta_ns += dev->min_delta_ns >> 1;
+
+			printk(KERN_WARNING
+			       "CE: %s increasing min_delta_ns to %lu nsec\n",
+			       dev->name ? dev->name : "?",
+			       dev->min_delta_ns << 1);
+
+			i = 0;
+		}
+
+		now = ktime_get();
+		expires = ktime_add_ns(now, dev->min_delta_ns);
+	}
+}
+
+/**
+ * tick_program_event
+ */
+int tick_program_event(ktime_t expires, int force)
+{
+	struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
+
+	return tick_dev_program_event(dev, expires, force);
+}
+
+/**
+ * tick_resume_onshot - resume oneshot mode
+ */
+void tick_resume_oneshot(void)
+{
+	struct tick_device *td = &__get_cpu_var(tick_cpu_device);
+	struct clock_event_device *dev = td->evtdev;
+
+	clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
+	tick_program_event(ktime_get(), 1);
+}
+
+/**
+ * tick_setup_oneshot - setup the event device for oneshot mode (hres or nohz)
+ */
+void tick_setup_oneshot(struct clock_event_device *newdev,
+			void (*handler)(struct clock_event_device *),
+			ktime_t next_event)
+{
+	newdev->event_handler = handler;
+	clockevents_set_mode(newdev, CLOCK_EVT_MODE_ONESHOT);
+	tick_dev_program_event(newdev, next_event, 1);
+}
+
+/**
+ * tick_switch_to_oneshot - switch to oneshot mode
+ */
+int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *))
+{
+	struct tick_device *td = &__get_cpu_var(tick_cpu_device);
+	struct clock_event_device *dev = td->evtdev;
+
+	if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT) ||
+		    !tick_device_is_functional(dev)) {
+
+		printk(KERN_INFO "Clockevents: "
+		       "could not switch to one-shot mode:");
+		if (!dev) {
+			printk(" no tick device\n");
+		} else {
+			if (!tick_device_is_functional(dev))
+				printk(" %s is not functional.\n", dev->name);
+			else
+				printk(" %s does not support one-shot mode.\n",
+				       dev->name);
+		}
+		return -EINVAL;
+	}
+
+	td->mode = TICKDEV_MODE_ONESHOT;
+	dev->event_handler = handler;
+	clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
+	tick_broadcast_switch_to_oneshot();
+	return 0;
+}
+
+#ifdef CONFIG_HIGH_RES_TIMERS
+/**
+ * tick_init_highres - switch to high resolution mode
+ *
+ * Called with interrupts disabled.
+ */
+int tick_init_highres(void)
+{
+	return tick_switch_to_oneshot(hrtimer_interrupt);
+}
+#endif
-- 
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