#include <linux/list.h>
#include <linux/cache.h>
#include <linux/timer.h>
+#include <linux/init.h>
#include <asm/div64.h>
#include <asm/io.h>
struct clocksource;
/**
+ * struct cyclecounter - hardware abstraction for a free running counter
+ * Provides completely state-free accessors to the underlying hardware.
+ * Depending on which hardware it reads, the cycle counter may wrap
+ * around quickly. Locking rules (if necessary) have to be defined
+ * by the implementor and user of specific instances of this API.
+ *
+ * @read: returns the current cycle value
+ * @mask: bitmask for two's complement
+ * subtraction of non 64 bit counters,
+ * see CLOCKSOURCE_MASK() helper macro
+ * @mult: cycle to nanosecond multiplier
+ * @shift: cycle to nanosecond divisor (power of two)
+ */
+struct cyclecounter {
+ cycle_t (*read)(const struct cyclecounter *cc);
+ cycle_t mask;
+ u32 mult;
+ u32 shift;
+};
+
+/**
+ * struct timecounter - layer above a %struct cyclecounter which counts nanoseconds
+ * Contains the state needed by timecounter_read() to detect
+ * cycle counter wrap around. Initialize with
+ * timecounter_init(). Also used to convert cycle counts into the
+ * corresponding nanosecond counts with timecounter_cyc2time(). Users
+ * of this code are responsible for initializing the underlying
+ * cycle counter hardware, locking issues and reading the time
+ * more often than the cycle counter wraps around. The nanosecond
+ * counter will only wrap around after ~585 years.
+ *
+ * @cc: the cycle counter used by this instance
+ * @cycle_last: most recent cycle counter value seen by
+ * timecounter_read()
+ * @nsec: continuously increasing count
+ */
+struct timecounter {
+ const struct cyclecounter *cc;
+ cycle_t cycle_last;
+ u64 nsec;
+};
+
+/**
+ * cyclecounter_cyc2ns - converts cycle counter cycles to nanoseconds
+ * @tc: Pointer to cycle counter.
+ * @cycles: Cycles
+ *
+ * XXX - This could use some mult_lxl_ll() asm optimization. Same code
+ * as in cyc2ns, but with unsigned result.
+ */
+static inline u64 cyclecounter_cyc2ns(const struct cyclecounter *cc,
+ cycle_t cycles)
+{
+ u64 ret = (u64)cycles;
+ ret = (ret * cc->mult) >> cc->shift;
+ return ret;
+}
+
+/**
+ * timecounter_init - initialize a time counter
+ * @tc: Pointer to time counter which is to be initialized/reset
+ * @cc: A cycle counter, ready to be used.
+ * @start_tstamp: Arbitrary initial time stamp.
+ *
+ * After this call the current cycle register (roughly) corresponds to
+ * the initial time stamp. Every call to timecounter_read() increments
+ * the time stamp counter by the number of elapsed nanoseconds.
+ */
+extern void timecounter_init(struct timecounter *tc,
+ const struct cyclecounter *cc,
+ u64 start_tstamp);
+
+/**
+ * timecounter_read - return nanoseconds elapsed since timecounter_init()
+ * plus the initial time stamp
+ * @tc: Pointer to time counter.
+ *
+ * In other words, keeps track of time since the same epoch as
+ * the function which generated the initial time stamp.
+ */
+extern u64 timecounter_read(struct timecounter *tc);
+
+/**
+ * timecounter_cyc2time - convert a cycle counter to same
+ * time base as values returned by
+ * timecounter_read()
+ * @tc: Pointer to time counter.
+ * @cycle: a value returned by tc->cc->read()
+ *
+ * Cycle counts that are converted correctly as long as they
+ * fall into the interval [-1/2 max cycle count, +1/2 max cycle count],
+ * with "max cycle count" == cs->mask+1.
+ *
+ * This allows conversion of cycle counter values which were generated
+ * in the past.
+ */
+extern u64 timecounter_cyc2time(struct timecounter *tc,
+ cycle_t cycle_tstamp);
+
+/**
* struct clocksource - hardware abstraction for a free running counter
* Provides mostly state-free accessors to the underlying hardware.
+ * This is the structure used for system time.
*
* @name: ptr to clocksource name
* @list: list head for registration
* 400-499: Perfect
* The ideal clocksource. A must-use where
* available.
- * @read: returns a cycle value
+ * @read: returns a cycle value, passes clocksource as argument
+ * @enable: optional function to enable the clocksource
+ * @disable: optional function to disable the clocksource
* @mask: bitmask for two's complement
* subtraction of non 64 bit counters
- * @mult: cycle to nanosecond multiplier (adjusted by NTP)
- * @mult_orig: cycle to nanosecond multiplier (unadjusted by NTP)
+ * @mult: cycle to nanosecond multiplier
* @shift: cycle to nanosecond divisor (power of two)
+ * @max_idle_ns: max idle time permitted by the clocksource (nsecs)
* @flags: flags describing special properties
* @vread: vsyscall based read
* @resume: resume function for the clocksource, if necessary
- * @cycle_interval: Used internally by timekeeping core, please ignore.
- * @xtime_interval: Used internally by timekeeping core, please ignore.
*/
struct clocksource {
/*
char *name;
struct list_head list;
int rating;
- cycle_t (*read)(void);
+ cycle_t (*read)(struct clocksource *cs);
+ int (*enable)(struct clocksource *cs);
+ void (*disable)(struct clocksource *cs);
cycle_t mask;
u32 mult;
- u32 mult_orig;
u32 shift;
+ u64 max_idle_ns;
unsigned long flags;
cycle_t (*vread)(void);
void (*resume)(void);
#define CLKSRC_FSYS_MMIO_SET(mmio, addr) do { } while (0)
#endif
- /* timekeeping specific data, ignore */
- cycle_t cycle_interval;
- u64 xtime_interval;
/*
* Second part is written at each timer interrupt
* Keep it in a different cache line to dirty no
* more than one cache line.
*/
cycle_t cycle_last ____cacheline_aligned_in_smp;
- u64 xtime_nsec;
- s64 error;
#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
/* Watchdog related data, used by the framework */
#endif
};
-extern struct clocksource *clock; /* current clocksource */
-
/*
* Clock source flags bits::
*/
#define CLOCK_SOURCE_WATCHDOG 0x10
#define CLOCK_SOURCE_VALID_FOR_HRES 0x20
+#define CLOCK_SOURCE_UNSTABLE 0x40
/* simplify initialization of mask field */
#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
}
/**
- * clocksource_read: - Access the clocksource's current cycle value
- * @cs: pointer to clocksource being read
- *
- * Uses the clocksource to return the current cycle_t value
- */
-static inline cycle_t clocksource_read(struct clocksource *cs)
-{
- return cs->read();
-}
-
-/**
- * cyc2ns - converts clocksource cycles to nanoseconds
- * @cs: Pointer to clocksource
- * @cycles: Cycles
+ * clocksource_cyc2ns - converts clocksource cycles to nanoseconds
*
- * Uses the clocksource and ntp ajdustment to convert cycle_ts to nanoseconds.
+ * Converts cycles to nanoseconds, using the given mult and shift.
*
* XXX - This could use some mult_lxl_ll() asm optimization
*/
-static inline s64 cyc2ns(struct clocksource *cs, cycle_t cycles)
+static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift)
{
- u64 ret = (u64)cycles;
- ret = (ret * cs->mult) >> cs->shift;
- return ret;
-}
-
-/**
- * clocksource_calculate_interval - Calculates a clocksource interval struct
- *
- * @c: Pointer to clocksource.
- * @length_nsec: Desired interval length in nanoseconds.
- *
- * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
- * pair and interval request.
- *
- * Unless you're the timekeeping code, you should not be using this!
- */
-static inline void clocksource_calculate_interval(struct clocksource *c,
- unsigned long length_nsec)
-{
- u64 tmp;
-
- /* Do the ns -> cycle conversion first, using original mult */
- tmp = length_nsec;
- tmp <<= c->shift;
- tmp += c->mult_orig/2;
- do_div(tmp, c->mult_orig);
-
- c->cycle_interval = (cycle_t)tmp;
- if (c->cycle_interval == 0)
- c->cycle_interval = 1;
-
- /* Go back from cycles -> shifted ns, this time use ntp adjused mult */
- c->xtime_interval = (u64)c->cycle_interval * c->mult;
+ return ((u64) cycles * mult) >> shift;
}
extern struct clocksource* clocksource_get_next(void);
extern void clocksource_change_rating(struct clocksource *cs, int rating);
extern void clocksource_resume(void);
+extern struct clocksource * __init __weak clocksource_default_clock(void);
+extern void clocksource_mark_unstable(struct clocksource *cs);
+
+extern void
+clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
+
+static inline void
+clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec)
+{
+ return clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
+ NSEC_PER_SEC, minsec);
+}
#ifdef CONFIG_GENERIC_TIME_VSYSCALL
-extern void update_vsyscall(struct timespec *ts, struct clocksource *c);
+extern void
+update_vsyscall(struct timespec *ts, struct clocksource *c, u32 mult);
extern void update_vsyscall_tz(void);
#else
-static inline void update_vsyscall(struct timespec *ts, struct clocksource *c)
+static inline void
+update_vsyscall(struct timespec *ts, struct clocksource *c, u32 mult)
{
}
}
#endif
+extern void timekeeping_notify(struct clocksource *clock);
+
#endif /* _LINUX_CLOCKSOURCE_H */