7d2f944a2b
MIPS has two functions to calculcate the mult/shift factors for clock sources and clock events at run time. ARM needs such functions as well. Implement a function which calculates the mult/shift factors based on the frequencies to which and from which is converted. The function also has a parameter to specify the minimum conversion range in seconds. This range is guaranteed not to produce a 64bit overflow when a value is multiplied with the calculated mult factor. The larger the conversion range the less becomes the conversion accuracy. Provide two inline wrappers which handle clock events and clock sources. For clock events the "from" frequency is nano seconds per second which corresponds to 1GHz and "to" is the device frequency. For clock sources "from" is the device frequency and "to" is nano seconds per second. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Mikael Pettersson <mikpe@it.uu.se> Acked-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Linus Walleij <linus.walleij@stericsson.com> Cc: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20091111134229.766673305@linutronix.de>
153 lines
4.4 KiB
C
153 lines
4.4 KiB
C
/* linux/include/linux/clockchips.h
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*
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* This file contains the structure definitions for clockchips.
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*
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* If you are not a clockchip, or the time of day code, you should
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* not be including this file!
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*/
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#ifndef _LINUX_CLOCKCHIPS_H
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#define _LINUX_CLOCKCHIPS_H
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#ifdef CONFIG_GENERIC_CLOCKEVENTS_BUILD
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#include <linux/clocksource.h>
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#include <linux/cpumask.h>
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#include <linux/ktime.h>
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#include <linux/notifier.h>
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struct clock_event_device;
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/* Clock event mode commands */
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enum clock_event_mode {
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CLOCK_EVT_MODE_UNUSED = 0,
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CLOCK_EVT_MODE_SHUTDOWN,
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CLOCK_EVT_MODE_PERIODIC,
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CLOCK_EVT_MODE_ONESHOT,
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CLOCK_EVT_MODE_RESUME,
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};
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/* Clock event notification values */
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enum clock_event_nofitiers {
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CLOCK_EVT_NOTIFY_ADD,
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CLOCK_EVT_NOTIFY_BROADCAST_ON,
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CLOCK_EVT_NOTIFY_BROADCAST_OFF,
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CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
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CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
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CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
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CLOCK_EVT_NOTIFY_SUSPEND,
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CLOCK_EVT_NOTIFY_RESUME,
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CLOCK_EVT_NOTIFY_CPU_DYING,
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CLOCK_EVT_NOTIFY_CPU_DEAD,
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};
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/*
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* Clock event features
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*/
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#define CLOCK_EVT_FEAT_PERIODIC 0x000001
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#define CLOCK_EVT_FEAT_ONESHOT 0x000002
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/*
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* x86(64) specific misfeatures:
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*
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* - Clockevent source stops in C3 State and needs broadcast support.
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* - Local APIC timer is used as a dummy device.
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*/
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#define CLOCK_EVT_FEAT_C3STOP 0x000004
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#define CLOCK_EVT_FEAT_DUMMY 0x000008
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/**
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* struct clock_event_device - clock event device descriptor
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* @name: ptr to clock event name
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* @features: features
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* @max_delta_ns: maximum delta value in ns
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* @min_delta_ns: minimum delta value in ns
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* @mult: nanosecond to cycles multiplier
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* @shift: nanoseconds to cycles divisor (power of two)
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* @rating: variable to rate clock event devices
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* @irq: IRQ number (only for non CPU local devices)
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* @cpumask: cpumask to indicate for which CPUs this device works
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* @set_next_event: set next event function
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* @set_mode: set mode function
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* @event_handler: Assigned by the framework to be called by the low
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* level handler of the event source
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* @broadcast: function to broadcast events
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* @list: list head for the management code
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* @mode: operating mode assigned by the management code
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* @next_event: local storage for the next event in oneshot mode
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*/
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struct clock_event_device {
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const char *name;
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unsigned int features;
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unsigned long max_delta_ns;
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unsigned long min_delta_ns;
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u32 mult;
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u32 shift;
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int rating;
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int irq;
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const struct cpumask *cpumask;
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int (*set_next_event)(unsigned long evt,
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struct clock_event_device *);
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void (*set_mode)(enum clock_event_mode mode,
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struct clock_event_device *);
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void (*event_handler)(struct clock_event_device *);
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void (*broadcast)(const struct cpumask *mask);
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struct list_head list;
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enum clock_event_mode mode;
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ktime_t next_event;
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};
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/*
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* Calculate a multiplication factor for scaled math, which is used to convert
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* nanoseconds based values to clock ticks:
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*
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* clock_ticks = (nanoseconds * factor) >> shift.
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*
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* div_sc is the rearranged equation to calculate a factor from a given clock
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* ticks / nanoseconds ratio:
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*
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* factor = (clock_ticks << shift) / nanoseconds
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*/
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static inline unsigned long div_sc(unsigned long ticks, unsigned long nsec,
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int shift)
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{
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uint64_t tmp = ((uint64_t)ticks) << shift;
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do_div(tmp, nsec);
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return (unsigned long) tmp;
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}
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/* Clock event layer functions */
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extern unsigned long clockevent_delta2ns(unsigned long latch,
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struct clock_event_device *evt);
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extern void clockevents_register_device(struct clock_event_device *dev);
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extern void clockevents_exchange_device(struct clock_event_device *old,
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struct clock_event_device *new);
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extern void clockevents_set_mode(struct clock_event_device *dev,
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enum clock_event_mode mode);
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extern int clockevents_register_notifier(struct notifier_block *nb);
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extern int clockevents_program_event(struct clock_event_device *dev,
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ktime_t expires, ktime_t now);
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extern void clockevents_handle_noop(struct clock_event_device *dev);
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static inline void
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clockevents_calc_mult_shift(struct clock_event_device *ce, u32 freq, u32 minsec)
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{
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return clocks_calc_mult_shift(&ce->mult, &ce->shift, NSEC_PER_SEC,
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freq, minsec);
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}
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#ifdef CONFIG_GENERIC_CLOCKEVENTS
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extern void clockevents_notify(unsigned long reason, void *arg);
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#else
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# define clockevents_notify(reason, arg) do { } while (0)
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#endif
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#else /* CONFIG_GENERIC_CLOCKEVENTS_BUILD */
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#define clockevents_notify(reason, arg) do { } while (0)
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#endif
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#endif
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