1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* linux/include/linux/clocksource.h 3 * 4 * This file contains the structure definitions for clocksources. 5 * 6 * If you are not a clocksource, or timekeeping code, you should 7 * not be including this file! 8 */ 9 #ifndef _LINUX_CLOCKSOURCE_H 10 #define _LINUX_CLOCKSOURCE_H 11 12 #include <linux/types.h> 13 #include <linux/timex.h> 14 #include <linux/time.h> 15 #include <linux/list.h> 16 #include <linux/cache.h> 17 #include <linux/timer.h> 18 #include <linux/init.h> 19 #include <linux/of.h> 20 #include <asm/div64.h> 21 #include <asm/io.h> 22 23 struct clocksource; 24 struct module; 25 26 #if defined(CONFIG_ARCH_CLOCKSOURCE_DATA) || \ 27 defined(CONFIG_GENERIC_GETTIMEOFDAY) 28 #include <asm/clocksource.h> 29 #endif 30 31 enum vdso_clock_mode { 32 VDSO_CLOCKMODE_NONE, 33 #ifdef CONFIG_GENERIC_GETTIMEOFDAY 34 VDSO_ARCH_CLOCKMODES, 35 #endif 36 VDSO_CLOCKMODE_MAX, 37 38 /* Indicator for time namespace VDSO */ 39 VDSO_CLOCKMODE_TIMENS = INT_MAX 40 }; 41 42 /** 43 * struct clocksource - hardware abstraction for a free running counter 44 * Provides mostly state-free accessors to the underlying hardware. 45 * This is the structure used for system time. 46 * 47 * @read: Returns a cycle value, passes clocksource as argument 48 * @mask: Bitmask for two's complement 49 * subtraction of non 64 bit counters 50 * @mult: Cycle to nanosecond multiplier 51 * @shift: Cycle to nanosecond divisor (power of two) 52 * @max_idle_ns: Maximum idle time permitted by the clocksource (nsecs) 53 * @maxadj: Maximum adjustment value to mult (~11%) 54 * @archdata: Optional arch-specific data 55 * @max_cycles: Maximum safe cycle value which won't overflow on 56 * multiplication 57 * @name: Pointer to clocksource name 58 * @list: List head for registration (internal) 59 * @rating: Rating value for selection (higher is better) 60 * To avoid rating inflation the following 61 * list should give you a guide as to how 62 * to assign your clocksource a rating 63 * 1-99: Unfit for real use 64 * Only available for bootup and testing purposes. 65 * 100-199: Base level usability. 66 * Functional for real use, but not desired. 67 * 200-299: Good. 68 * A correct and usable clocksource. 69 * 300-399: Desired. 70 * A reasonably fast and accurate clocksource. 71 * 400-499: Perfect 72 * The ideal clocksource. A must-use where 73 * available. 74 * @flags: Flags describing special properties 75 * @enable: Optional function to enable the clocksource 76 * @disable: Optional function to disable the clocksource 77 * @suspend: Optional suspend function for the clocksource 78 * @resume: Optional resume function for the clocksource 79 * @mark_unstable: Optional function to inform the clocksource driver that 80 * the watchdog marked the clocksource unstable 81 * @tick_stable: Optional function called periodically from the watchdog 82 * code to provide stable syncrhonization points 83 * @wd_list: List head to enqueue into the watchdog list (internal) 84 * @cs_last: Last clocksource value for clocksource watchdog 85 * @wd_last: Last watchdog value corresponding to @cs_last 86 * @owner: Module reference, must be set by clocksource in modules 87 * 88 * Note: This struct is not used in hotpathes of the timekeeping code 89 * because the timekeeper caches the hot path fields in its own data 90 * structure, so no cache line alignment is required, 91 * 92 * The pointer to the clocksource itself is handed to the read 93 * callback. If you need extra information there you can wrap struct 94 * clocksource into your own struct. Depending on the amount of 95 * information you need you should consider to cache line align that 96 * structure. 97 */ 98 struct clocksource { 99 u64 (*read)(struct clocksource *cs); 100 u64 mask; 101 u32 mult; 102 u32 shift; 103 u64 max_idle_ns; 104 u32 maxadj; 105 #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA 106 struct arch_clocksource_data archdata; 107 #endif 108 u64 max_cycles; 109 const char *name; 110 struct list_head list; 111 int rating; 112 enum vdso_clock_mode vdso_clock_mode; 113 unsigned long flags; 114 115 int (*enable)(struct clocksource *cs); 116 void (*disable)(struct clocksource *cs); 117 void (*suspend)(struct clocksource *cs); 118 void (*resume)(struct clocksource *cs); 119 void (*mark_unstable)(struct clocksource *cs); 120 void (*tick_stable)(struct clocksource *cs); 121 122 /* private: */ 123 #ifdef CONFIG_CLOCKSOURCE_WATCHDOG 124 /* Watchdog related data, used by the framework */ 125 struct list_head wd_list; 126 u64 cs_last; 127 u64 wd_last; 128 #endif 129 struct module *owner; 130 }; 131 132 /* 133 * Clock source flags bits:: 134 */ 135 #define CLOCK_SOURCE_IS_CONTINUOUS 0x01 136 #define CLOCK_SOURCE_MUST_VERIFY 0x02 137 138 #define CLOCK_SOURCE_WATCHDOG 0x10 139 #define CLOCK_SOURCE_VALID_FOR_HRES 0x20 140 #define CLOCK_SOURCE_UNSTABLE 0x40 141 #define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80 142 #define CLOCK_SOURCE_RESELECT 0x100 143 144 /* simplify initialization of mask field */ 145 #define CLOCKSOURCE_MASK(bits) GENMASK_ULL((bits) - 1, 0) 146 147 static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from) 148 { 149 /* freq = cyc/from 150 * mult/2^shift = ns/cyc 151 * mult = ns/cyc * 2^shift 152 * mult = from/freq * 2^shift 153 * mult = from * 2^shift / freq 154 * mult = (from<<shift) / freq 155 */ 156 u64 tmp = ((u64)from) << shift_constant; 157 158 tmp += freq/2; /* round for do_div */ 159 do_div(tmp, freq); 160 161 return (u32)tmp; 162 } 163 164 /** 165 * clocksource_khz2mult - calculates mult from khz and shift 166 * @khz: Clocksource frequency in KHz 167 * @shift_constant: Clocksource shift factor 168 * 169 * Helper functions that converts a khz counter frequency to a timsource 170 * multiplier, given the clocksource shift value 171 */ 172 static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) 173 { 174 return clocksource_freq2mult(khz, shift_constant, NSEC_PER_MSEC); 175 } 176 177 /** 178 * clocksource_hz2mult - calculates mult from hz and shift 179 * @hz: Clocksource frequency in Hz 180 * @shift_constant: Clocksource shift factor 181 * 182 * Helper functions that converts a hz counter 183 * frequency to a timsource multiplier, given the 184 * clocksource shift value 185 */ 186 static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) 187 { 188 return clocksource_freq2mult(hz, shift_constant, NSEC_PER_SEC); 189 } 190 191 /** 192 * clocksource_cyc2ns - converts clocksource cycles to nanoseconds 193 * @cycles: cycles 194 * @mult: cycle to nanosecond multiplier 195 * @shift: cycle to nanosecond divisor (power of two) 196 * 197 * Converts clocksource cycles to nanoseconds, using the given @mult and @shift. 198 * The code is optimized for performance and is not intended to work 199 * with absolute clocksource cycles (as those will easily overflow), 200 * but is only intended to be used with relative (delta) clocksource cycles. 201 * 202 * XXX - This could use some mult_lxl_ll() asm optimization 203 */ 204 static inline s64 clocksource_cyc2ns(u64 cycles, u32 mult, u32 shift) 205 { 206 return ((u64) cycles * mult) >> shift; 207 } 208 209 210 extern int clocksource_unregister(struct clocksource*); 211 extern void clocksource_touch_watchdog(void); 212 extern void clocksource_change_rating(struct clocksource *cs, int rating); 213 extern void clocksource_suspend(void); 214 extern void clocksource_resume(void); 215 extern struct clocksource * __init clocksource_default_clock(void); 216 extern void clocksource_mark_unstable(struct clocksource *cs); 217 extern void 218 clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles); 219 extern u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 now); 220 221 extern u64 222 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles); 223 extern void 224 clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); 225 226 /* 227 * Don't call __clocksource_register_scale directly, use 228 * clocksource_register_hz/khz 229 */ 230 extern int 231 __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq); 232 extern void 233 __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq); 234 235 /* 236 * Don't call this unless you are a default clocksource 237 * (AKA: jiffies) and absolutely have to. 238 */ 239 static inline int __clocksource_register(struct clocksource *cs) 240 { 241 return __clocksource_register_scale(cs, 1, 0); 242 } 243 244 static inline int clocksource_register_hz(struct clocksource *cs, u32 hz) 245 { 246 return __clocksource_register_scale(cs, 1, hz); 247 } 248 249 static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) 250 { 251 return __clocksource_register_scale(cs, 1000, khz); 252 } 253 254 static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz) 255 { 256 __clocksource_update_freq_scale(cs, 1, hz); 257 } 258 259 static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz) 260 { 261 __clocksource_update_freq_scale(cs, 1000, khz); 262 } 263 264 #ifdef CONFIG_ARCH_CLOCKSOURCE_INIT 265 extern void clocksource_arch_init(struct clocksource *cs); 266 #else 267 static inline void clocksource_arch_init(struct clocksource *cs) { } 268 #endif 269 270 extern int timekeeping_notify(struct clocksource *clock); 271 272 extern u64 clocksource_mmio_readl_up(struct clocksource *); 273 extern u64 clocksource_mmio_readl_down(struct clocksource *); 274 extern u64 clocksource_mmio_readw_up(struct clocksource *); 275 extern u64 clocksource_mmio_readw_down(struct clocksource *); 276 277 extern int clocksource_mmio_init(void __iomem *, const char *, 278 unsigned long, int, unsigned, u64 (*)(struct clocksource *)); 279 280 extern int clocksource_i8253_init(void); 281 282 #define TIMER_OF_DECLARE(name, compat, fn) \ 283 OF_DECLARE_1_RET(timer, name, compat, fn) 284 285 #ifdef CONFIG_TIMER_PROBE 286 extern void timer_probe(void); 287 #else 288 static inline void timer_probe(void) {} 289 #endif 290 291 #define TIMER_ACPI_DECLARE(name, table_id, fn) \ 292 ACPI_DECLARE_PROBE_ENTRY(timer, name, table_id, 0, NULL, 0, fn) 293 294 #endif /* _LINUX_CLOCKSOURCE_H */ 295