Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=f8381cba04ba8173fd5a2b8e5cd8b3290ee13a98
Commit:     f8381cba04ba8173fd5a2b8e5cd8b3290ee13a98
Parent:     906568c9c668ff994f4078932ec6ae1e3950d1af
Author:     Thomas Gleixner <[EMAIL PROTECTED]>
AuthorDate: Fri Feb 16 01:28:02 2007 -0800
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Fri Feb 16 08:13:59 2007 -0800

    [PATCH] tick-management: broadcast functionality
    
    With Ingo Molnar <[EMAIL PROTECTED]>
    
    Add broadcast functionality, so per cpu clock event devices can be 
registered
    as dummy devices or switched from/to broadcast on demand.  The broadcast
    function distributes the events via the broadcast function of the clock 
event
    device.  This is primarily designed to replace the switch apic timer to / 
from
    IPI in power states, where the apic stops.
    
    Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
    Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
    Cc: john stultz <[EMAIL PROTECTED]>
    Cc: Roman Zippel <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 kernel/time/Makefile         |    5 +-
 kernel/time/tick-broadcast.c |  270 ++++++++++++++++++++++++++++++++++++++++++
 kernel/time/tick-common.c    |   53 +++++++--
 kernel/time/tick-internal.h  |   65 ++++++++++
 4 files changed, 382 insertions(+), 11 deletions(-)

diff --git a/kernel/time/Makefile b/kernel/time/Makefile
index 337daef..a941743 100644
--- a/kernel/time/Makefile
+++ b/kernel/time/Makefile
@@ -1,4 +1,5 @@
 obj-y += ntp.o clocksource.o jiffies.o
 
-obj-$(CONFIG_GENERIC_CLOCKEVENTS)      += clockevents.o
-obj-$(CONFIG_GENERIC_CLOCKEVENTS)      += tick-common.o
+obj-$(CONFIG_GENERIC_CLOCKEVENTS)              += clockevents.o
+obj-$(CONFIG_GENERIC_CLOCKEVENTS)              += tick-common.o
+obj-$(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST)    += tick-broadcast.o
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
new file mode 100644
index 0000000..0ee4968
--- /dev/null
+++ b/kernel/time/tick-broadcast.c
@@ -0,0 +1,270 @@
+/*
+ * 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 <[EMAIL PROTECTED]>
+ * 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;
+DEFINE_SPINLOCK(tick_broadcast_lock);
+
+/*
+ * 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);
+       }
+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);
+}
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 46e4381..48167a6 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -20,17 +20,19 @@
 #include <linux/sched.h>
 #include <linux/tick.h>
 
+#include "tick-internal.h"
+
 /*
  * Tick devices
  */
-static DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
+DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
 /*
  * Tick next event: keeps track of the tick time
  */
-static ktime_t tick_next_period;
-static ktime_t tick_period;
+ktime_t tick_next_period;
+ktime_t tick_period;
 static int tick_do_timer_cpu = -1;
-static DEFINE_SPINLOCK(tick_device_lock);
+DEFINE_SPINLOCK(tick_device_lock);
 
 /*
  * Periodic tick
@@ -78,9 +80,13 @@ void tick_handle_periodic(struct clock_event_device *dev)
 /*
  * Setup the device for a periodic tick
  */
-void tick_setup_periodic(struct clock_event_device *dev)
+void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
 {
-       dev->event_handler = tick_handle_periodic;
+       tick_set_periodic_handler(dev, broadcast);
+
+       /* Broadcast setup ? */
+       if (!tick_device_is_functional(dev))
+               return;
 
        if (dev->features & CLOCK_EVT_FEAT_PERIODIC) {
                clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC);
@@ -145,6 +151,15 @@ static void tick_setup_device(struct tick_device *td,
        if (!cpus_equal(newdev->cpumask, cpumask))
                irq_set_affinity(newdev->irq, cpumask);
 
+       /*
+        * When global broadcasting is active, check if the current
+        * device is registered as a placeholder for broadcast mode.
+        * This allows us to handle this x86 misfeature in a generic
+        * way.
+        */
+       if (tick_device_uses_broadcast(newdev, cpu))
+               return;
+
        if (td->mode == TICKDEV_MODE_PERIODIC)
                tick_setup_periodic(newdev, 0);
 }
@@ -197,19 +212,33 @@ static int tick_check_new_device(struct 
clock_event_device *newdev)
                 * Check the rating
                 */
                if (curdev->rating >= newdev->rating)
-                       goto out;
+                       goto out_bc;
        }
 
        /*
         * Replace the eventually existing device by the new
-        * device.
+        * device. If the current device is the broadcast device, do
+        * not give it back to the clockevents layer !
         */
+       if (tick_is_broadcast_device(curdev)) {
+               clockevents_set_mode(curdev, CLOCK_EVT_MODE_SHUTDOWN);
+               curdev = NULL;
+       }
        clockevents_exchange_device(curdev, newdev);
        tick_setup_device(td, newdev, cpu, cpumask);
-       ret = NOTIFY_STOP;
 
+       spin_unlock_irqrestore(&tick_device_lock, flags);
+       return NOTIFY_STOP;
+
+out_bc:
+       /*
+        * Can the new device be used as a broadcast device ?
+        */
+       if (tick_check_broadcast_device(newdev))
+               ret = NOTIFY_STOP;
 out:
        spin_unlock_irqrestore(&tick_device_lock, flags);
+
        return ret;
 }
 
@@ -251,7 +280,13 @@ static int tick_notify(struct notifier_block *nb, unsigned 
long reason,
        case CLOCK_EVT_NOTIFY_ADD:
                return tick_check_new_device(dev);
 
+       case CLOCK_EVT_NOTIFY_BROADCAST_ON:
+       case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
+               tick_broadcast_on_off(reason, dev);
+               break;
+
        case CLOCK_EVT_NOTIFY_CPU_DEAD:
+               tick_shutdown_broadcast(dev);
                tick_shutdown(dev);
                break;
 
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
new file mode 100644
index 0000000..9272f44
--- /dev/null
+++ b/kernel/time/tick-internal.h
@@ -0,0 +1,65 @@
+/*
+ * tick internal variable and functions used by low/high res code
+ */
+DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
+extern spinlock_t tick_device_lock;
+extern ktime_t tick_next_period;
+extern ktime_t tick_period;
+
+extern void tick_setup_periodic(struct clock_event_device *dev, int broadcast);
+extern void tick_handle_periodic(struct clock_event_device *dev);
+
+/*
+ * Broadcasting support
+ */
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
+extern int tick_do_broadcast(cpumask_t mask);
+extern struct tick_device tick_broadcast_device;
+extern spinlock_t tick_broadcast_lock;
+
+extern int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu);
+extern int tick_check_broadcast_device(struct clock_event_device *dev);
+extern int tick_is_broadcast_device(struct clock_event_device *dev);
+extern void tick_broadcast_on_off(unsigned long reason, int *oncpu);
+extern void tick_shutdown_broadcast(unsigned int *cpup);
+
+extern void
+tick_set_periodic_handler(struct clock_event_device *dev, int broadcast);
+
+#else /* !BROADCAST */
+
+static inline int tick_check_broadcast_device(struct clock_event_device *dev)
+{
+       return 0;
+}
+
+static inline int tick_is_broadcast_device(struct clock_event_device *dev)
+{
+       return 0;
+}
+static inline int tick_device_uses_broadcast(struct clock_event_device *dev,
+                                            int cpu)
+{
+       return 0;
+}
+static inline void tick_do_periodic_broadcast(struct clock_event_device *d) { }
+static inline void tick_broadcast_on_off(unsigned long reason, int *oncpu) { }
+static inline void tick_shutdown_broadcast(unsigned int *cpup) { }
+
+/*
+ * Set the periodic handler in non broadcast mode
+ */
+static inline void tick_set_periodic_handler(struct clock_event_device *dev,
+                                            int broadcast)
+{
+       dev->event_handler = tick_handle_periodic;
+}
+#endif /* !BROADCAST */
+
+/*
+ * Check, if the device is functional or a dummy for broadcast
+ */
+static inline int tick_device_is_functional(struct clock_event_device *dev)
+{
+       return !(dev->features & CLOCK_EVT_FEAT_DUMMY);
+}
-
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