[PATCH] clockevents: add core functionality

Architectures register their clock event devices, in the clock events core.
Users of the clockevents core can get clock event devices for their use.  The
clockevents core code provides notification mechanisms for various clock
related management events.

This allows to control the clock event devices without the architectures
having to worry about the details of function assignment.  This is also a
preliminary for high resolution timers and dynamic ticks to allow the core
code to control the clock functionality without intrusive changes to the
architecture code.

[Fixes-by: Ingo Molnar <mingo@elte.hu>]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 142 insertions, 0 deletions

diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
new file mode 100644
index 000000000000..4ea7e7bcfafe
--- /dev/null
+++ b/include/linux/clockchips.h
@@ -0,0 +1,142 @@
+/*  linux/include/linux/clockchips.h
+ *
+ *  This file contains the structure definitions for clockchips.
+ *
+ *  If you are not a clockchip, or the time of day code, you should
+ *  not be including this file!
+ */
+#ifndef _LINUX_CLOCKCHIPS_H
+#define _LINUX_CLOCKCHIPS_H
+
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+
+#include <linux/clocksource.h>
+#include <linux/cpumask.h>
+#include <linux/ktime.h>
+#include <linux/notifier.h>
+
+struct clock_event_device;
+
+/* Clock event mode commands */
+enum clock_event_mode {
+        CLOCK_EVT_MODE_UNUSED = 0,
+        CLOCK_EVT_MODE_SHUTDOWN,
+        CLOCK_EVT_MODE_PERIODIC,
+        CLOCK_EVT_MODE_ONESHOT,
+};
+
+/* Clock event notification values */
+enum clock_event_nofitiers {
+        CLOCK_EVT_NOTIFY_ADD,
+        CLOCK_EVT_NOTIFY_BROADCAST_ON,
+        CLOCK_EVT_NOTIFY_BROADCAST_OFF,
+        CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
+        CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
+        CLOCK_EVT_NOTIFY_SUSPEND,
+        CLOCK_EVT_NOTIFY_RESUME,
+        CLOCK_EVT_NOTIFY_CPU_DEAD,
+};
+
+/*
+ * Clock event features
+ */
+#define CLOCK_EVT_FEAT_PERIODIC         0x000001
+#define CLOCK_EVT_FEAT_ONESHOT          0x000002
+/*
+ * x86(64) specific misfeatures:
+ *
+ * - Clockevent source stops in C3 State and needs broadcast support.
+ * - Local APIC timer is used as a dummy device.
+ */
+#define CLOCK_EVT_FEAT_C3STOP           0x000004
+#define CLOCK_EVT_FEAT_DUMMY            0x000008
+
+/**
+ * struct clock_event_device - clock event device descriptor
+ * @name:               ptr to clock event name
+ * @hints:              usage hints
+ * @max_delta_ns:       maximum delta value in ns
+ * @min_delta_ns:       minimum delta value in ns
+ * @mult:               nanosecond to cycles multiplier
+ * @shift:              nanoseconds to cycles divisor (power of two)
+ * @rating:             variable to rate clock event devices
+ * @irq:                irq number (only for non cpu local devices)
+ * @cpumask:            cpumask to indicate for which cpus this device works
+ * @set_next_event:     set next event
+ * @set_mode:           set mode function
+ * @evthandler:         Assigned by the framework to be called by the low
+ *                      level handler of the event source
+ * @broadcast:          function to broadcast events
+ * @list:               list head for the management code
+ * @mode:               operating mode assigned by the management code
+ * @next_event:         local storage for the next event in oneshot mode
+ */
+struct clock_event_device {
+        const char              *name;
+        unsigned int            features;
+        unsigned long           max_delta_ns;
+        unsigned long           min_delta_ns;
+        unsigned long           mult;
+        int                     shift;
+        int                     rating;
+        int                     irq;
+        cpumask_t               cpumask;
+        int                     (*set_next_event)(unsigned long evt,
+                                                  struct clock_event_device *);
+        void                    (*set_mode)(enum clock_event_mode mode,
+                                            struct clock_event_device *);
+        void                    (*event_handler)(struct clock_event_device *);
+        void                    (*broadcast)(cpumask_t mask);
+        struct list_head        list;
+        enum clock_event_mode   mode;
+        ktime_t                 next_event;
+};
+
+/*
+ * Calculate a multiplication factor for scaled math, which is used to convert
+ * nanoseconds based values to clock ticks:
+ *
+ * clock_ticks = (nanoseconds * factor) >> shift.
+ *
+ * div_sc is the rearranged equation to calculate a factor from a given clock
+ * ticks / nanoseconds ratio:
+ *
+ * factor = (clock_ticks << shift) / nanoseconds
+ */
+static inline unsigned long div_sc(unsigned long ticks, unsigned long nsec,
+                                   int shift)
+{
+        uint64_t tmp = ((uint64_t)ticks) << shift;
+
+        do_div(tmp, nsec);
+        return (unsigned long) tmp;
+}
+
+/* Clock event layer functions */
+extern unsigned long clockevent_delta2ns(unsigned long latch,
+                                         struct clock_event_device *evt);
+extern void clockevents_register_device(struct clock_event_device *dev);
+
+extern void clockevents_exchange_device(struct clock_event_device *old,
+                                        struct clock_event_device *new);
+extern
+struct clock_event_device *clockevents_request_device(unsigned int features,
+                                                      cpumask_t cpumask);
+extern void clockevents_release_device(struct clock_event_device *dev);
+extern void clockevents_set_mode(struct clock_event_device *dev,
+                                 enum clock_event_mode mode);
+extern int clockevents_register_notifier(struct notifier_block *nb);
+extern void clockevents_unregister_notifier(struct notifier_block *nb);
+extern int clockevents_program_event(struct clock_event_device *dev,
+                                     ktime_t expires, ktime_t now);
+
+extern void clockevents_notify(unsigned long reason, void *arg);
+
+#else
+
+static inline void clockevents_resume_events(void) { }
+#define clockevents_notify(reason, arg) do { } while (0)
+
+#endif
+
+#endif