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/timer.h> 17 #include <linux/init.h> 18 #include <asm/div64.h> 19 #include <asm/io.h> 20 21 struct clocksource; 22 struct module; 23 24 #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA 25 #include <asm/clocksource.h> 26 #endif 27 28 /** 29 * struct clocksource - hardware abstraction for a free running counter 30 * Provides mostly state-free accessors to the underlying hardware. 31 * This is the structure used for system time. 32 * 33 * @name: ptr to clocksource name 34 * @list: list head for registration 35 * @rating: rating value for selection (higher is better) 36 * To avoid rating inflation the following 37 * list should give you a guide as to how 38 * to assign your clocksource a rating 39 * 1-99: Unfit for real use 40 * Only available for bootup and testing purposes. 41 * 100-199: Base level usability. 42 * Functional for real use, but not desired. 43 * 200-299: Good. 44 * A correct and usable clocksource. 45 * 300-399: Desired. 46 * A reasonably fast and accurate clocksource. 47 * 400-499: Perfect 48 * The ideal clocksource. A must-use where 49 * available. 50 * @read: returns a cycle value, passes clocksource as argument 51 * @enable: optional function to enable the clocksource 52 * @disable: optional function to disable the clocksource 53 * @mask: bitmask for two's complement 54 * subtraction of non 64 bit counters 55 * @mult: cycle to nanosecond multiplier 56 * @shift: cycle to nanosecond divisor (power of two) 57 * @max_idle_ns: max idle time permitted by the clocksource (nsecs) 58 * @maxadj: maximum adjustment value to mult (~11%) 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 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_register(struct clocksource*); 182 extern int clocksource_unregister(struct clocksource*); 183 extern void clocksource_touch_watchdog(void); 184 extern struct clocksource* clocksource_get_next(void); 185 extern void clocksource_change_rating(struct clocksource *cs, int rating); 186 extern void clocksource_suspend(void); 187 extern void clocksource_resume(void); 188 extern struct clocksource * __init clocksource_default_clock(void); 189 extern void clocksource_mark_unstable(struct clocksource *cs); 190 191 extern u64 192 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask); 193 extern void 194 clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); 195 196 /* 197 * Don't call __clocksource_register_scale directly, use 198 * clocksource_register_hz/khz 199 */ 200 extern int 201 __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq); 202 extern void 203 __clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq); 204 205 static inline int clocksource_register_hz(struct clocksource *cs, u32 hz) 206 { 207 return __clocksource_register_scale(cs, 1, hz); 208 } 209 210 static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) 211 { 212 return __clocksource_register_scale(cs, 1000, khz); 213 } 214 215 static inline void __clocksource_updatefreq_hz(struct clocksource *cs, u32 hz) 216 { 217 __clocksource_updatefreq_scale(cs, 1, hz); 218 } 219 220 static inline void __clocksource_updatefreq_khz(struct clocksource *cs, u32 khz) 221 { 222 __clocksource_updatefreq_scale(cs, 1000, khz); 223 } 224 225 226 extern int timekeeping_notify(struct clocksource *clock); 227 228 extern cycle_t clocksource_mmio_readl_up(struct clocksource *); 229 extern cycle_t clocksource_mmio_readl_down(struct clocksource *); 230 extern cycle_t clocksource_mmio_readw_up(struct clocksource *); 231 extern cycle_t clocksource_mmio_readw_down(struct clocksource *); 232 233 extern int clocksource_mmio_init(void __iomem *, const char *, 234 unsigned long, int, unsigned, cycle_t (*)(struct clocksource *)); 235 236 extern int clocksource_i8253_init(void); 237 238 #define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \ 239 OF_DECLARE_1(clksrc, name, compat, fn) 240 241 #ifdef CONFIG_CLKSRC_OF 242 extern void clocksource_of_init(void); 243 #else 244 static inline void clocksource_of_init(void) {} 245 #endif 246 247 #endif /* _LINUX_CLOCKSOURCE_H */ 248