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From: Thomas Gleixner on 1 Oct 2006 19:20
From: Thomas Gleixner <tglx(a)linutronix.de>

Add a framework to manage clock event devices.

We have two types of clock event devices:
- global events (one device per system)
- local events (one device per cpu)

We assign the various time(r) related interrupts to those devices:

- global tick (advances jiffies)
- update process times (per cpu)
- profiling (per cpu)
- next timer events (per cpu)

Architectures register their clock event devices, with specific capability
bits set, and the framework code assigns the appropriate event handler
to the event device. The functionality is assigned via an event handler to
avoid runtime evalutation of the assigned function bits.

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.

When high resolution timers and dynamic ticks are disabled, there is no
change in the behaviour of the system.

Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de>
Signed-off-by: Ingo Molnar <mingo(a)elte.hu>
--
include/linux/clockchips.h | 122 +++++++++
include/linux/hrtimer.h | 3
init/main.c | 2
kernel/hrtimer.c | 6
kernel/time/Makefile | 2
kernel/time/clockevents.c | 567 +++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 700 insertions(+), 2 deletions(-)

Index: linux-2.6.18-mm2/include/linux/clockchips.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.18-mm2/include/linux/clockchips.h 2006-10-02 00:55:53.000000000 +0200
@@ -0,0 +1,122 @@
+/* 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/interrupt.h>
+
+struct clock_event_device;
+
+/* Clock event mode commands */
+enum clock_event_mode {
+ CLOCK_EVT_PERIODIC,
+ CLOCK_EVT_ONESHOT,
+ CLOCK_EVT_SHUTDOWN,
+};
+
+/*
+ * Clock event capability flags:
+ *
+ * CAP_TICK: The event source should be used for the periodic tick
+ * CAP_UPDATE: The event source handler should call update_process_times()
+ * CAP_PROFILE: The event source handler should call profile_tick()
+ * CAP_NEXTEVT: The event source can be reprogrammed in oneshot mode and is
+ * a per cpu event source.
+ *
+ * The capability flags are used to select the appropriate handler for an event
+ * source. On an i386 UP system the PIT can serve all of the functionalities,
+ * while on a SMP system the PIT is solely used for the periodic tick and the
+ * local APIC timers are used for UPDATE / PROFILE / NEXTEVT. To avoid the run
+ * time query of those flags, the clock events layer assigns the appropriate
+ * event handler function, which contains only the selected calls, to the
+ * event.
+ */
+#define CLOCK_CAP_TICK 0x000001
+#define CLOCK_CAP_UPDATE 0x000002
+#define CLOCK_CAP_PROFILE 0x000004
+#ifdef CONFIG_HIGH_RES_TIMERS
+# define CLOCK_CAP_NEXTEVT 0x000008
+#else
+# define CLOCK_CAP_NEXTEVT 0x000000
+#endif
+
+#define CLOCK_BASE_CAPS_MASK (CLOCK_CAP_TICK | CLOCK_CAP_PROFILE | \
+ CLOCK_CAP_UPDATE)
+#define CLOCK_CAPS_MASK (CLOCK_BASE_CAPS_MASK | CLOCK_CAP_NEXTEVT)
+
+/**
+ * struct clock_event_device - clock event descriptor
+ *
+ * @name: ptr to clock event name
+ * @capabilities: capabilities of the event chip
+ * @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)
+ * @set_next_event: set next event
+ * @set_mode: set mode function
+ * @suspend: suspend function (optional)
+ * @resume: resume function (optional)
+ * @evthandler: Assigned by the framework to be called by the low
+ * level handler of the event source
+ */
+struct clock_event_device {
+ const char *name;
+ unsigned int capabilities;
+ unsigned long max_delta_ns;
+ unsigned long min_delta_ns;
+ unsigned long mult;
+ int shift;
+ void (*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 pt_regs *regs);
+};
+
+/*
+ * 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 int register_local_clockevent(struct clock_event_device *);
+extern int register_global_clockevent(struct clock_event_device *);
+extern unsigned long clockevent_delta2ns(unsigned long latch,
+ struct clock_event_device *evt);
+extern void clockevents_init(void);
+
+extern int clockevents_init_next_event(void);
+extern int clockevents_set_next_event(ktime_t expires, int force);
+extern int clockevents_next_event_available(void);
+extern void clockevents_resume_events(void);
+
+#else
+# define clockevents_init() do { } while(0)
+# define clockevents_resume_events() do { } while(0)
+#endif
+
+#endif
Index: linux-2.6.18-mm2/include/linux/hrtimer.h
===================================================================
--- linux-2.6.18-mm2.orig/include/linux/hrtimer.h 2006-10-02 00:55:53.000000000 +0200
+++ linux-2.6.18-mm2/include/linux/hrtimer.h 2006-10-02 00:55:53.000000000 +0200
@@ -144,6 +144,9 @@ struct hrtimer_cpu_base {
* is expired in the next softirq when the clock was advanced.
*/
#define clock_was_set() do { } while (0)
+#define hrtimer_clock_notify() do { } while (0)
+extern ktime_t ktime_get(void);
 | 
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