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