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 * @max_cycles: maximum safe cycle value which won't overflow on multiplication 60 * @flags: flags describing special properties 61 * @archdata: arch-specific data 62 * @suspend: suspend function for the clocksource, if necessary 63 * @resume: resume function for the clocksource, if necessary 64 * @owner: module reference, must be set by clocksource in modules 65 */ 66 struct clocksource { 67 /* 68 * Hotpath data, fits in a single cache line when the 69 * clocksource itself is cacheline aligned. 70 */ 71 cycle_t (*read)(struct clocksource *cs); 72 cycle_t mask; 73 u32 mult; 74 u32 shift; 75 u64 max_idle_ns; 76 u32 maxadj; 77 #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA 78 struct arch_clocksource_data archdata; 79 #endif 80 u64 max_cycles; 81 const char *name; 82 struct list_head list; 83 int rating; 84 int (*enable)(struct clocksource *cs); 85 void (*disable)(struct clocksource *cs); 86 unsigned long flags; 87 void (*suspend)(struct clocksource *cs); 88 void (*resume)(struct clocksource *cs); 89 90 /* private: */ 91 #ifdef CONFIG_CLOCKSOURCE_WATCHDOG 92 /* Watchdog related data, used by the framework */ 93 struct list_head wd_list; 94 cycle_t cs_last; 95 cycle_t wd_last; 96 #endif 97 struct module *owner; 98 } ____cacheline_aligned; 99 100 /* 101 * Clock source flags bits:: 102 */ 103 #define CLOCK_SOURCE_IS_CONTINUOUS 0x01 104 #define CLOCK_SOURCE_MUST_VERIFY 0x02 105 106 #define CLOCK_SOURCE_WATCHDOG 0x10 107 #define CLOCK_SOURCE_VALID_FOR_HRES 0x20 108 #define CLOCK_SOURCE_UNSTABLE 0x40 109 #define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80 110 #define CLOCK_SOURCE_RESELECT 0x100 111 112 /* simplify initialization of mask field */ 113 #define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1) 114 115 /** 116 * clocksource_khz2mult - calculates mult from khz and shift 117 * @khz: Clocksource frequency in KHz 118 * @shift_constant: Clocksource shift factor 119 * 120 * Helper functions that converts a khz counter frequency to a timsource 121 * multiplier, given the clocksource shift value 122 */ 123 static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) 124 { 125 /* khz = cyc/(Million ns) 126 * mult/2^shift = ns/cyc 127 * mult = ns/cyc * 2^shift 128 * mult = 1Million/khz * 2^shift 129 * mult = 1000000 * 2^shift / khz 130 * mult = (1000000<<shift) / khz 131 */ 132 u64 tmp = ((u64)1000000) << shift_constant; 133 134 tmp += khz/2; /* round for do_div */ 135 do_div(tmp, khz); 136 137 return (u32)tmp; 138 } 139 140 /** 141 * clocksource_hz2mult - calculates mult from hz and shift 142 * @hz: Clocksource frequency in Hz 143 * @shift_constant: Clocksource shift factor 144 * 145 * Helper functions that converts a hz counter 146 * frequency to a timsource multiplier, given the 147 * clocksource shift value 148 */ 149 static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) 150 { 151 /* hz = cyc/(Billion ns) 152 * mult/2^shift = ns/cyc 153 * mult = ns/cyc * 2^shift 154 * mult = 1Billion/hz * 2^shift 155 * mult = 1000000000 * 2^shift / hz 156 * mult = (1000000000<<shift) / hz 157 */ 158 u64 tmp = ((u64)1000000000) << shift_constant; 159 160 tmp += hz/2; /* round for do_div */ 161 do_div(tmp, hz); 162 163 return (u32)tmp; 164 } 165 166 /** 167 * clocksource_cyc2ns - converts clocksource cycles to nanoseconds 168 * @cycles: cycles 169 * @mult: cycle to nanosecond multiplier 170 * @shift: cycle to nanosecond divisor (power of two) 171 * 172 * Converts cycles to nanoseconds, using the given mult and shift. 173 * 174 * XXX - This could use some mult_lxl_ll() asm optimization 175 */ 176 static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift) 177 { 178 return ((u64) cycles * mult) >> shift; 179 } 180 181 182 extern int clocksource_unregister(struct clocksource*); 183 extern void clocksource_touch_watchdog(void); 184 extern void clocksource_change_rating(struct clocksource *cs, int rating); 185 extern void clocksource_suspend(void); 186 extern void clocksource_resume(void); 187 extern struct clocksource * __init clocksource_default_clock(void); 188 extern void clocksource_mark_unstable(struct clocksource *cs); 189 190 extern u64 191 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles); 192 extern void 193 clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); 194 195 /* 196 * Don't call __clocksource_register_scale directly, use 197 * clocksource_register_hz/khz 198 */ 199 extern int 200 __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq); 201 extern void 202 __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq); 203 204 /* 205 * Don't call this unless you are a default clocksource 206 * (AKA: jiffies) and absolutely have to. 207 */ 208 static inline int __clocksource_register(struct clocksource *cs) 209 { 210 return __clocksource_register_scale(cs, 1, 0); 211 } 212 213 static inline int clocksource_register_hz(struct clocksource *cs, u32 hz) 214 { 215 return __clocksource_register_scale(cs, 1, hz); 216 } 217 218 static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) 219 { 220 return __clocksource_register_scale(cs, 1000, khz); 221 } 222 223 static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz) 224 { 225 __clocksource_update_freq_scale(cs, 1, hz); 226 } 227 228 static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz) 229 { 230 __clocksource_update_freq_scale(cs, 1000, khz); 231 } 232 233 234 extern int timekeeping_notify(struct clocksource *clock); 235 236 extern cycle_t clocksource_mmio_readl_up(struct clocksource *); 237 extern cycle_t clocksource_mmio_readl_down(struct clocksource *); 238 extern cycle_t clocksource_mmio_readw_up(struct clocksource *); 239 extern cycle_t clocksource_mmio_readw_down(struct clocksource *); 240 241 extern int clocksource_mmio_init(void __iomem *, const char *, 242 unsigned long, int, unsigned, cycle_t (*)(struct clocksource *)); 243 244 extern int clocksource_i8253_init(void); 245 246 #define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \ 247 OF_DECLARE_1(clksrc, name, compat, fn) 248 249 #ifdef CONFIG_CLKSRC_PROBE 250 extern void clocksource_probe(void); 251 #else 252 static inline void clocksource_probe(void) {} 253 #endif 254 255 #define CLOCKSOURCE_ACPI_DECLARE(name, table_id, fn) \ 256 ACPI_DECLARE_PROBE_ENTRY(clksrc, name, table_id, 0, NULL, 0, fn) 257 258 #endif /* _LINUX_CLOCKSOURCE_H */ 259