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