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  1. /*  linux/include/linux/clocksource.h
  2.  *
  3.  *  This file contains the structure definitions for clocksources.
  4.  *
  5.  *  If you are not a clocksource, or timekeeping code, you should
  6.  *  not be including this file!
  7.  */
  8. #ifndef _LINUX_CLOCKSOURCE_H
  9. #define _LINUX_CLOCKSOURCE_H
  10.  
  11. #include <linux/types.h>
  12. #include <linux/timex.h>
  13. #include <linux/time.h>
  14. #include <linux/list.h>
  15. #include <linux/cache.h>
  16. #include <linux/init.h>
  17. #include <asm/div64.h>
  18. #include <asm/io.h>
  19.  
  20. struct clocksource;
  21. struct module;
  22.  
  23. #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
  24. #include <asm/clocksource.h>
  25. #endif
  26.  
  27. /**
  28.  * struct clocksource - hardware abstraction for a free running counter
  29.  *      Provides mostly state-free accessors to the underlying hardware.
  30.  *      This is the structure used for system time.
  31.  *
  32.  * @name:               ptr to clocksource name
  33.  * @list:               list head for registration
  34.  * @rating:             rating value for selection (higher is better)
  35.  *                      To avoid rating inflation the following
  36.  *                      list should give you a guide as to how
  37.  *                      to assign your clocksource a rating
  38.  *                      1-99: Unfit for real use
  39.  *                              Only available for bootup and testing purposes.
  40.  *                      100-199: Base level usability.
  41.  *                              Functional for real use, but not desired.
  42.  *                      200-299: Good.
  43.  *                              A correct and usable clocksource.
  44.  *                      300-399: Desired.
  45.  *                              A reasonably fast and accurate clocksource.
  46.  *                      400-499: Perfect
  47.  *                              The ideal clocksource. A must-use where
  48.  *                              available.
  49.  * @read:               returns a cycle value, passes clocksource as argument
  50.  * @enable:             optional function to enable the clocksource
  51.  * @disable:            optional function to disable the clocksource
  52.  * @mask:               bitmask for two's complement
  53.  *                      subtraction of non 64 bit counters
  54.  * @mult:               cycle to nanosecond multiplier
  55.  * @shift:              cycle to nanosecond divisor (power of two)
  56.  * @max_idle_ns:        max idle time permitted by the clocksource (nsecs)
  57.  * @maxadj:             maximum adjustment value to mult (~11%)
  58.  * @max_cycles:         maximum safe cycle value which won't overflow on multiplication
  59.  * @flags:              flags describing special properties
  60.  * @archdata:           arch-specific data
  61.  * @suspend:            suspend function for the clocksource, if necessary
  62.  * @resume:             resume function for the clocksource, if necessary
  63.  * @owner:              module reference, must be set by clocksource in modules
  64.  */
  65. struct clocksource {
  66.         /*
  67.          * Hotpath data, fits in a single cache line when the
  68.          * clocksource itself is cacheline aligned.
  69.          */
  70.         cycle_t (*read)(struct clocksource *cs);
  71.         cycle_t mask;
  72.         u32 mult;
  73.         u32 shift;
  74.         u64 max_idle_ns;
  75.         u32 maxadj;
  76. #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
  77.         struct arch_clocksource_data archdata;
  78. #endif
  79.         u64 max_cycles;
  80.         const char *name;
  81.         struct list_head list;
  82.         int rating;
  83.         int (*enable)(struct clocksource *cs);
  84.         void (*disable)(struct clocksource *cs);
  85.         unsigned long flags;
  86.         void (*suspend)(struct clocksource *cs);
  87.         void (*resume)(struct clocksource *cs);
  88.  
  89.         /* private: */
  90. #ifdef CONFIG_CLOCKSOURCE_WATCHDOG
  91.         /* Watchdog related data, used by the framework */
  92.         struct list_head wd_list;
  93.         cycle_t cs_last;
  94.         cycle_t wd_last;
  95. #endif
  96.         struct module *owner;
  97. } ____cacheline_aligned;
  98.  
  99. /*
  100.  * Clock source flags bits::
  101.  */
  102. #define CLOCK_SOURCE_IS_CONTINUOUS              0x01
  103. #define CLOCK_SOURCE_MUST_VERIFY                0x02
  104.  
  105. #define CLOCK_SOURCE_WATCHDOG                   0x10
  106. #define CLOCK_SOURCE_VALID_FOR_HRES             0x20
  107. #define CLOCK_SOURCE_UNSTABLE                   0x40
  108. #define CLOCK_SOURCE_SUSPEND_NONSTOP            0x80
  109. #define CLOCK_SOURCE_RESELECT                   0x100
  110.  
  111. /* simplify initialization of mask field */
  112. #define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
  113.  
  114. /**
  115.  * clocksource_khz2mult - calculates mult from khz and shift
  116.  * @khz:                Clocksource frequency in KHz
  117.  * @shift_constant:     Clocksource shift factor
  118.  *
  119.  * Helper functions that converts a khz counter frequency to a timsource
  120.  * multiplier, given the clocksource shift value
  121.  */
  122. static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)
  123. {
  124.         /*  khz = cyc/(Million ns)
  125.          *  mult/2^shift  = ns/cyc
  126.          *  mult = ns/cyc * 2^shift
  127.          *  mult = 1Million/khz * 2^shift
  128.          *  mult = 1000000 * 2^shift / khz
  129.          *  mult = (1000000<<shift) / khz
  130.          */
  131.         u64 tmp = ((u64)1000000) << shift_constant;
  132.  
  133.         tmp += khz/2; /* round for do_div */
  134.         do_div(tmp, khz);
  135.  
  136.         return (u32)tmp;
  137. }
  138.  
  139. /**
  140.  * clocksource_hz2mult - calculates mult from hz and shift
  141.  * @hz:                 Clocksource frequency in Hz
  142.  * @shift_constant:     Clocksource shift factor
  143.  *
  144.  * Helper functions that converts a hz counter
  145.  * frequency to a timsource multiplier, given the
  146.  * clocksource shift value
  147.  */
  148. static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant)
  149. {
  150.         /*  hz = cyc/(Billion ns)
  151.          *  mult/2^shift  = ns/cyc
  152.          *  mult = ns/cyc * 2^shift
  153.          *  mult = 1Billion/hz * 2^shift
  154.          *  mult = 1000000000 * 2^shift / hz
  155.          *  mult = (1000000000<<shift) / hz
  156.          */
  157.         u64 tmp = ((u64)1000000000) << shift_constant;
  158.  
  159.         tmp += hz/2; /* round for do_div */
  160.         do_div(tmp, hz);
  161.  
  162.         return (u32)tmp;
  163. }
  164.  
  165. /**
  166.  * clocksource_cyc2ns - converts clocksource cycles to nanoseconds
  167.  * @cycles:     cycles
  168.  * @mult:       cycle to nanosecond multiplier
  169.  * @shift:      cycle to nanosecond divisor (power of two)
  170.  *
  171.  * Converts cycles to nanoseconds, using the given mult and shift.
  172.  *
  173.  * XXX - This could use some mult_lxl_ll() asm optimization
  174.  */
  175. static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift)
  176. {
  177.         return ((u64) cycles * mult) >> shift;
  178. }
  179.  
  180.  
  181. extern int clocksource_unregister(struct clocksource*);
  182. extern void clocksource_touch_watchdog(void);
  183. extern void clocksource_change_rating(struct clocksource *cs, int rating);
  184. extern void clocksource_suspend(void);
  185. extern void clocksource_resume(void);
  186. extern struct clocksource * __init clocksource_default_clock(void);
  187. extern void clocksource_mark_unstable(struct clocksource *cs);
  188.  
  189. extern u64
  190. clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles);
  191. extern void
  192. clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
  193.  
  194. /*
  195.  * Don't call __clocksource_register_scale directly, use
  196.  * clocksource_register_hz/khz
  197.  */
  198. extern int
  199. __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq);
  200. extern void
  201. __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq);
  202.  
  203. /*
  204.  * Don't call this unless you are a default clocksource
  205.  * (AKA: jiffies) and absolutely have to.
  206.  */
  207. static inline int __clocksource_register(struct clocksource *cs)
  208. {
  209.         return __clocksource_register_scale(cs, 1, 0);
  210. }
  211.  
  212. static inline int clocksource_register_hz(struct clocksource *cs, u32 hz)
  213. {
  214.         return __clocksource_register_scale(cs, 1, hz);
  215. }
  216.  
  217. static inline int clocksource_register_khz(struct clocksource *cs, u32 khz)
  218. {
  219.         return __clocksource_register_scale(cs, 1000, khz);
  220. }
  221.  
  222. static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz)
  223. {
  224.         __clocksource_update_freq_scale(cs, 1, hz);
  225. }
  226.  
  227. static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz)
  228. {
  229.         __clocksource_update_freq_scale(cs, 1000, khz);
  230. }
  231.  
  232.  
  233. extern int timekeeping_notify(struct clocksource *clock);
  234.  
  235. extern cycle_t clocksource_mmio_readl_up(struct clocksource *);
  236. extern cycle_t clocksource_mmio_readl_down(struct clocksource *);
  237. extern cycle_t clocksource_mmio_readw_up(struct clocksource *);
  238. extern cycle_t clocksource_mmio_readw_down(struct clocksource *);
  239.  
  240. extern int clocksource_mmio_init(void __iomem *, const char *,
  241.         unsigned long, int, unsigned, cycle_t (*)(struct clocksource *));
  242.  
  243. extern int clocksource_i8253_init(void);
  244.  
  245. #define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \
  246.         OF_DECLARE_1(clksrc, name, compat, fn)
  247.  
  248. #ifdef CONFIG_CLKSRC_PROBE
  249. extern void clocksource_probe(void);
  250. #else
  251. static inline void clocksource_probe(void) {}
  252. #endif
  253.  
  254. #define CLOCKSOURCE_ACPI_DECLARE(name, table_id, fn)            \
  255.         ACPI_DECLARE_PROBE_ENTRY(clksrc, name, table_id, 0, NULL, 0, fn)
  256.  
  257. #endif /* _LINUX_CLOCKSOURCE_H */
  258.