/* * This file is part of the coreboot project. * * Copyright (C) 2013 Google, Inc. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2 of the License. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ #ifndef TIMER_H #define TIMER_H #include <types.h> #define NSECS_PER_SEC 1000000000 #define USECS_PER_SEC 1000000 #define MSECS_PER_SEC 1000 #define USECS_PER_MSEC (USECS_PER_SEC / MSECS_PER_SEC) /* The time structures are defined to be a representation of the time since * coreboot started executing one of its stages. The reason for using structures * is to allow for changes in the future. The structures' details are exposed * so that the compiler can allocate space on the stack and use in other * structures. In other words, accessing any field within this structure * outside of the core timer code is not supported. */ struct mono_time { long microseconds; }; /* A timeout_callback structure is used for the book keeping for scheduling * work in the future. When a callback is called the structure can be * re-used for scheduling as it is not being tracked by the core timer * library any more. */ struct timeout_callback { void *priv; void (*callback)(struct timeout_callback *tocb); /* Not for public use. The timer library uses the fields below. */ struct mono_time expiration; }; /* Obtain the current monotonic time. The assumption is that the time counts * up from the value 0 with value 0 being the point when the timer was * initialized. Additionally, the timer is assumed to only be valid for the * duration of the boot. * * Note that any implementations of timer_monotonic_get() * need to ensure its timesource does not roll over within 10 secs. The reason * is that the time between calls to timer_monotonic_get() may be on order * of 10 seconds. */ void timer_monotonic_get(struct mono_time *mt); /* Returns 1 if callbacks still present in the queue. 0 if no timers left. */ int timers_run(void); /* Schedule a callback to be ran microseconds from time of invocation. * 0 returned on success, < 0 on error. */ int timer_sched_callback(struct timeout_callback *tocb, unsigned long us); /* Set an absolute time to a number of microseconds. */ static inline void mono_time_set_usecs(struct mono_time *mt, long us) { mt->microseconds = us; } /* Set an absolute time to a number of milliseconds. */ static inline void mono_time_set_msecs(struct mono_time *mt, long ms) { mt->microseconds = ms * USECS_PER_MSEC; } /* Add microseconds to an absolute time. */ static inline void mono_time_add_usecs(struct mono_time *mt, long us) { mt->microseconds += us; } /* Add milliseconds to an absolute time. */ static inline void mono_time_add_msecs(struct mono_time *mt, long ms) { mono_time_add_usecs(mt, ms * USECS_PER_MSEC); } /* Compare two absolute times: Return -1, 0, or 1 if t1 is <, =, or > t2, * respectively. */ static inline int mono_time_cmp(const struct mono_time *t1, const struct mono_time *t2) { if (t1->microseconds == t2->microseconds) return 0; if (t1->microseconds < t2->microseconds) return -1; return 1; } /* Return true if t1 after t2 */ static inline int mono_time_after(const struct mono_time *t1, const struct mono_time *t2) { return mono_time_cmp(t1, t2) > 0; } /* Return true if t1 before t2. */ static inline int mono_time_before(const struct mono_time *t1, const struct mono_time *t2) { return mono_time_cmp(t1, t2) < 0; } /* Return time difference between t1 and t2. i.e. t2 - t1. */ static inline long mono_time_diff_microseconds(const struct mono_time *t1, const struct mono_time *t2) { return t2->microseconds - t1->microseconds; } struct stopwatch { struct mono_time start; struct mono_time current; struct mono_time expires; }; static inline void stopwatch_init(struct stopwatch *sw) { if (IS_ENABLED(CONFIG_HAVE_MONOTONIC_TIMER)) timer_monotonic_get(&sw->start); else sw->start.microseconds = 0; sw->current = sw->expires = sw->start; } static inline void stopwatch_init_usecs_expire(struct stopwatch *sw, long us) { stopwatch_init(sw); mono_time_add_usecs(&sw->expires, us); } static inline void stopwatch_init_msecs_expire(struct stopwatch *sw, long ms) { stopwatch_init_usecs_expire(sw, USECS_PER_MSEC * ms); } /* * Tick the stopwatch to collect the current time. */ static inline void stopwatch_tick(struct stopwatch *sw) { if (IS_ENABLED(CONFIG_HAVE_MONOTONIC_TIMER)) timer_monotonic_get(&sw->current); else sw->current.microseconds = 0; } /* * Tick and check the stopwatch for expiration. Returns non-zero on exipration. */ static inline int stopwatch_expired(struct stopwatch *sw) { stopwatch_tick(sw); return !mono_time_before(&sw->current, &sw->expires); } /* * Tick and check the stopwatch as long as it has not expired. */ static inline void stopwatch_wait_until_expired(struct stopwatch *sw) { while (!stopwatch_expired(sw)) ; } /* * Return number of microseconds since starting the stopwatch. */ static inline long stopwatch_duration_usecs(struct stopwatch *sw) { /* * If the stopwatch hasn't been ticked (current == start) tick * the stopwatch to gather the accumulated time. */ if (!mono_time_cmp(&sw->start, &sw->current)) stopwatch_tick(sw); return mono_time_diff_microseconds(&sw->start, &sw->current); } static inline long stopwatch_duration_msecs(struct stopwatch *sw) { return stopwatch_duration_usecs(sw) / USECS_PER_MSEC; } /* * Helper macro to wait until a condition becomes true or a timeout elapses. * * condition: a C expression to wait for * timeout: timeout, in microseconds * * Returns: * 0 if the condition still evaluates to false after the timeout elapsed, * >0 if the condition evaluates to true. The return value is the amount of * microseconds waited (at least 1). */ #define wait_us(timeout_us, condition) \ ({ \ long __ret = 0; \ struct stopwatch __sw; \ stopwatch_init_usecs_expire(&__sw, timeout_us); \ do { \ if (condition) { \ stopwatch_tick(&__sw); \ __ret = stopwatch_duration_usecs(&__sw); \ if (!__ret) /* make sure it evaluates to true */\ __ret = 1; \ break; \ } \ } while (!stopwatch_expired(&__sw)); \ __ret; \ }) #define wait_ms(timeout_ms, condition) \ DIV_ROUND_UP(wait_us((timeout_ms) * USECS_PER_MSEC, condition), \ USECS_PER_MSEC) #endif /* TIMER_H */