1 files changed, 480 insertions, 0 deletions
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
new file mode 100644
index 000000000000..12b3efeb9f6f
--- /dev/null
+++ b/kernel/time/tick-broadcast.c
@@ -0,0 +1,480 @@
+/*
+ * linux/kernel/time/tick-broadcast.c
+ *
+ * This file contains functions which emulate a local clock-event
+ * device via a broadcast event source.
+ *
+ * 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/irq.h>
+#include <linux/percpu.h>
+#include <linux/profile.h>
+#include <linux/sched.h>
+#include <linux/tick.h>
+
+#include "tick-internal.h"
+
+/*
+ * Broadcast support for broken x86 hardware, where the local apic
+ * timer stops in C3 state.
+ */
+
+struct tick_device tick_broadcast_device;
+static cpumask_t tick_broadcast_mask;
+static DEFINE_SPINLOCK(tick_broadcast_lock);
+
+/*
+ * Debugging: see timer_list.c
+ */
+struct tick_device *tick_get_broadcast_device(void)
+{
+	return &tick_broadcast_device;
+}
+
+cpumask_t *tick_get_broadcast_mask(void)
+{
+	return &tick_broadcast_mask;
+}
+
+/*
+ * Start the device in periodic mode
+ */
+static void tick_broadcast_start_periodic(struct clock_event_device *bc)
+{
+	if (bc && bc->mode == CLOCK_EVT_MODE_SHUTDOWN)
+		tick_setup_periodic(bc, 1);
+}
+
+/*
+ * Check, if the device can be utilized as broadcast device:
+ */
+int tick_check_broadcast_device(struct clock_event_device *dev)
+{
+	if (tick_broadcast_device.evtdev ||
+	    (dev->features & CLOCK_EVT_FEAT_C3STOP))
+		return 0;
+
+	clockevents_exchange_device(NULL, dev);
+	tick_broadcast_device.evtdev = dev;
+	if (!cpus_empty(tick_broadcast_mask))
+		tick_broadcast_start_periodic(dev);
+	return 1;
+}
+
+/*
+ * Check, if the device is the broadcast device
+ */
+int tick_is_broadcast_device(struct clock_event_device *dev)
+{
+	return (dev && tick_broadcast_device.evtdev == dev);
+}
+
+/*
+ * Check, if the device is disfunctional and a place holder, which
+ * needs to be handled by the broadcast device.
+ */
+int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
+{
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+	/*
+	 * Devices might be registered with both periodic and oneshot
+	 * mode disabled. This signals, that the device needs to be
+	 * operated from the broadcast device and is a placeholder for
+	 * the cpu local device.
+	 */
+	if (!tick_device_is_functional(dev)) {
+		dev->event_handler = tick_handle_periodic;
+		cpu_set(cpu, tick_broadcast_mask);
+		tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
+		ret = 1;
+	}
+
+	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+	return ret;
+}
+
+/*
+ * Broadcast the event to the cpus, which are set in the mask
+ */
+int tick_do_broadcast(cpumask_t mask)
+{
+	int ret = 0, cpu = smp_processor_id();
+	struct tick_device *td;
+
+	/*
+	 * Check, if the current cpu is in the mask
+	 */
+	if (cpu_isset(cpu, mask)) {
+		cpu_clear(cpu, mask);
+		td = &per_cpu(tick_cpu_device, cpu);
+		td->evtdev->event_handler(td->evtdev);
+		ret = 1;
+	}
+
+	if (!cpus_empty(mask)) {
+		/*
+		 * It might be necessary to actually check whether the devices
+		 * have different broadcast functions. For now, just use the
+		 * one of the first device. This works as long as we have this
+		 * misfeature only on x86 (lapic)
+		 */
+		cpu = first_cpu(mask);
+		td = &per_cpu(tick_cpu_device, cpu);
+		td->evtdev->broadcast(mask);
+		ret = 1;
+	}
+	return ret;
+}
+
+/*
+ * Periodic broadcast:
+ * - invoke the broadcast handlers
+ */
+static void tick_do_periodic_broadcast(void)
+{
+	cpumask_t mask;
+
+	spin_lock(&tick_broadcast_lock);
+
+	cpus_and(mask, cpu_online_map, tick_broadcast_mask);
+	tick_do_broadcast(mask);
+
+	spin_unlock(&tick_broadcast_lock);
+}
+
+/*
+ * Event handler for periodic broadcast ticks
+ */
+static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
+{
+	dev->next_event.tv64 = KTIME_MAX;
+
+	tick_do_periodic_broadcast();
+
+	/*
+	 * The device is in periodic mode. No reprogramming necessary:
+	 */
+	if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
+		return;
+
+	/*
+	 * Setup the next period for devices, which do not have
+	 * periodic mode:
+	 */
+	for (;;) {
+		ktime_t next = ktime_add(dev->next_event, tick_period);
+
+		if (!clockevents_program_event(dev, next, ktime_get()))
+			return;
+		tick_do_periodic_broadcast();
+	}
+}
+
+/*
+ * Powerstate information: The system enters/leaves a state, where
+ * affected devices might stop
+ */
+static void tick_do_broadcast_on_off(void *why)
+{
+	struct clock_event_device *bc, *dev;
+	struct tick_device *td;
+	unsigned long flags, *reason = why;
+	int cpu;
+
+	spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+	cpu = smp_processor_id();
+	td = &per_cpu(tick_cpu_device, cpu);
+	dev = td->evtdev;
+	bc = tick_broadcast_device.evtdev;
+
+	/*
+	 * Is the device in broadcast mode forever or is it not
+	 * affected by the powerstate ?
+	 */
+	if (!dev || !tick_device_is_functional(dev) ||
+	    !(dev->features & CLOCK_EVT_FEAT_C3STOP))
+		goto out;
+
+	if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_ON) {
+		if (!cpu_isset(cpu, tick_broadcast_mask)) {
+			cpu_set(cpu, tick_broadcast_mask);
+			if (td->mode == TICKDEV_MODE_PERIODIC)
+				clockevents_set_mode(dev,
+						     CLOCK_EVT_MODE_SHUTDOWN);
+		}
+	} else {
+		if (cpu_isset(cpu, tick_broadcast_mask)) {
+			cpu_clear(cpu, tick_broadcast_mask);
+			if (td->mode == TICKDEV_MODE_PERIODIC)
+				tick_setup_periodic(dev, 0);
+		}
+	}
+
+	if (cpus_empty(tick_broadcast_mask))
+		clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
+	else {
+		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+			tick_broadcast_start_periodic(bc);
+		else
+			tick_broadcast_setup_oneshot(bc);
+	}
+out:
+	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+/*
+ * Powerstate information: The system enters/leaves a state, where
+ * affected devices might stop.
+ */
+void tick_broadcast_on_off(unsigned long reason, int *oncpu)
+{
+	int cpu = get_cpu();
+
+	if (cpu == *oncpu)
+		tick_do_broadcast_on_off(&reason);
+	else
+		smp_call_function_single(*oncpu, tick_do_broadcast_on_off,
+					 &reason, 1, 1);
+	put_cpu();
+}
+
+/*
+ * Set the periodic handler depending on broadcast on/off
+ */
+void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
+{
+	if (!broadcast)
+		dev->event_handler = tick_handle_periodic;
+	else
+		dev->event_handler = tick_handle_periodic_broadcast;
+}
+
+/*
+ * Remove a CPU from broadcasting
+ */
+void tick_shutdown_broadcast(unsigned int *cpup)
+{
+	struct clock_event_device *bc;
+	unsigned long flags;
+	unsigned int cpu = *cpup;
+
+	spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+	bc = tick_broadcast_device.evtdev;
+	cpu_clear(cpu, tick_broadcast_mask);
+
+	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
+		if (bc && cpus_empty(tick_broadcast_mask))
+			clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
+	}
+
+	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+#ifdef CONFIG_TICK_ONESHOT
+
+static cpumask_t tick_broadcast_oneshot_mask;
+
+/*
+ * Debugging: see timer_list.c
+ */
+cpumask_t *tick_get_broadcast_oneshot_mask(void)
+{
+	return &tick_broadcast_oneshot_mask;
+}
+
+static int tick_broadcast_set_event(ktime_t expires, int force)
+{
+	struct clock_event_device *bc = tick_broadcast_device.evtdev;
+	ktime_t now = ktime_get();
+	int res;
+
+	for(;;) {
+		res = clockevents_program_event(bc, expires, now);
+		if (!res || !force)
+			return res;
+		now = ktime_get();
+		expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));
+	}
+}
+
+/*
+ * Reprogram the broadcast device:
+ *
+ * Called with tick_broadcast_lock held and interrupts disabled.
+ */
+static int tick_broadcast_reprogram(void)
+{
+	ktime_t expires = { .tv64 = KTIME_MAX };
+	struct tick_device *td;
+	int cpu;
+
+	/*
+	 * Find the event which expires next:
+	 */
+	for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
+	     cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
+		td = &per_cpu(tick_cpu_device, cpu);
+		if (td->evtdev->next_event.tv64 < expires.tv64)
+			expires = td->evtdev->next_event;
+	}
+
+	if (expires.tv64 == KTIME_MAX)
+		return 0;
+
+	return tick_broadcast_set_event(expires, 0);
+}
+
+/*
+ * Handle oneshot mode broadcasting
+ */
+static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
+{
+	struct tick_device *td;
+	cpumask_t mask;
+	ktime_t now;
+	int cpu;
+
+	spin_lock(&tick_broadcast_lock);
+again:
+	dev->next_event.tv64 = KTIME_MAX;
+	mask = CPU_MASK_NONE;
+	now = ktime_get();
+	/* Find all expired events */
+	for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
+	     cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
+		td = &per_cpu(tick_cpu_device, cpu);
+		if (td->evtdev->next_event.tv64 <= now.tv64)
+			cpu_set(cpu, mask);
+	}
+
+	/*
+	 * Wakeup the cpus which have an expired event. The broadcast
+	 * device is reprogrammed in the return from idle code.
+	 */
+	if (!tick_do_broadcast(mask)) {
+		/*
+		 * The global event did not expire any CPU local
+		 * events. This happens in dyntick mode, as the
+		 * maximum PIT delta is quite small.
+		 */
+		if (tick_broadcast_reprogram())
+			goto again;
+	}
+	spin_unlock(&tick_broadcast_lock);
+}
+
+/*
+ * Powerstate information: The system enters/leaves a state, where
+ * affected devices might stop
+ */
+void tick_broadcast_oneshot_control(unsigned long reason)
+{
+	struct clock_event_device *bc, *dev;
+	struct tick_device *td;
+	unsigned long flags;
+	int cpu;
+
+	spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+	/*
+	 * Periodic mode does not care about the enter/exit of power
+	 * states
+	 */
+	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+		goto out;
+
+	bc = tick_broadcast_device.evtdev;
+	cpu = smp_processor_id();
+	td = &per_cpu(tick_cpu_device, cpu);
+	dev = td->evtdev;
+
+	if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
+		goto out;
+
+	if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
+		if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
+			cpu_set(cpu, tick_broadcast_oneshot_mask);
+			clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
+			if (dev->next_event.tv64 < bc->next_event.tv64)
+				tick_broadcast_set_event(dev->next_event, 1);
+		}
+	} else {
+		if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
+			cpu_clear(cpu, tick_broadcast_oneshot_mask);
+			clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
+			if (dev->next_event.tv64 != KTIME_MAX)
+				tick_program_event(dev->next_event, 1);
+		}
+	}
+
+out:
+	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+/**
+ * tick_broadcast_setup_highres - setup the broadcast device for highres
+ */
+void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
+{
+	if (bc->mode != CLOCK_EVT_MODE_ONESHOT) {
+		bc->event_handler = tick_handle_oneshot_broadcast;
+		clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
+		bc->next_event.tv64 = KTIME_MAX;
+	}
+}
+
+/*
+ * Select oneshot operating mode for the broadcast device
+ */
+void tick_broadcast_switch_to_oneshot(void)
+{
+	struct clock_event_device *bc;
+	unsigned long flags;
+
+	spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+	tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
+	bc = tick_broadcast_device.evtdev;
+	if (bc)
+		tick_broadcast_setup_oneshot(bc);
+	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+
+/*
+ * Remove a dead CPU from broadcasting
+ */
+void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
+{
+	struct clock_event_device *bc;
+	unsigned long flags;
+	unsigned int cpu = *cpup;
+
+	spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+	bc = tick_broadcast_device.evtdev;
+	cpu_clear(cpu, tick_broadcast_oneshot_mask);
+
+	if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT) {
+		if (bc && cpus_empty(tick_broadcast_oneshot_mask))
+			clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
+	}
+
+	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+#endif