| /* system clock support */ |
| |
| /* |
| * Copyright (c) 1997-2015 Wind River Systems, Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| |
| #include <kernel_structs.h> |
| #include <toolchain.h> |
| #include <sections.h> |
| #include <wait_q.h> |
| #include <drivers/system_timer.h> |
| |
| #ifdef CONFIG_SYS_CLOCK_EXISTS |
| #ifdef _NON_OPTIMIZED_TICKS_PER_SEC |
| #warning "non-optimized system clock frequency chosen: performance may suffer" |
| #endif |
| #endif |
| |
| #ifdef CONFIG_SYS_CLOCK_EXISTS |
| int sys_clock_us_per_tick = 1000000 / sys_clock_ticks_per_sec; |
| int sys_clock_hw_cycles_per_tick = |
| CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC / sys_clock_ticks_per_sec; |
| #if defined(CONFIG_TIMER_READS_ITS_FREQUENCY_AT_RUNTIME) |
| int sys_clock_hw_cycles_per_sec = CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC; |
| #endif |
| #else |
| /* don't initialize to avoid division-by-zero error */ |
| int sys_clock_us_per_tick; |
| int sys_clock_hw_cycles_per_tick; |
| #if defined(CONFIG_TIMER_READS_ITS_FREQUENCY_AT_RUNTIME) |
| int sys_clock_hw_cycles_per_sec; |
| #endif |
| #endif |
| |
| /* updated by timer driver for tickless, stays at 1 for non-tickless */ |
| int32_t _sys_idle_elapsed_ticks = 1; |
| |
| int64_t _sys_clock_tick_count; |
| |
| /** |
| * |
| * @brief Return the lower part of the current system tick count |
| * |
| * @return the current system tick count |
| * |
| */ |
| uint32_t _tick_get_32(void) |
| { |
| return (uint32_t)_sys_clock_tick_count; |
| } |
| FUNC_ALIAS(_tick_get_32, sys_tick_get_32, uint32_t); |
| |
| uint32_t k_uptime_get_32(void) |
| { |
| return __ticks_to_ms(_tick_get_32()); |
| } |
| |
| /** |
| * |
| * @brief Return the current system tick count |
| * |
| * @return the current system tick count |
| * |
| */ |
| int64_t _tick_get(void) |
| { |
| int64_t tmp_sys_clock_tick_count; |
| /* |
| * Lock the interrupts when reading _sys_clock_tick_count 64-bit |
| * variable. Some architectures (x86) do not handle 64-bit atomically, |
| * so we have to lock the timer interrupt that causes change of |
| * _sys_clock_tick_count |
| */ |
| unsigned int imask = irq_lock(); |
| |
| tmp_sys_clock_tick_count = _sys_clock_tick_count; |
| irq_unlock(imask); |
| return tmp_sys_clock_tick_count; |
| } |
| FUNC_ALIAS(_tick_get, sys_tick_get, int64_t); |
| |
| int64_t k_uptime_get(void) |
| { |
| return __ticks_to_ms(_tick_get()); |
| } |
| |
| /** |
| * |
| * @brief Return number of ticks since a reference time |
| * |
| * This function is meant to be used in contained fragments of code. The first |
| * call to it in a particular code fragment fills in a reference time variable |
| * which then gets passed and updated every time the function is called. From |
| * the second call on, the delta between the value passed to it and the current |
| * tick count is the return value. Since the first call is meant to only fill in |
| * the reference time, its return value should be discarded. |
| * |
| * Since a code fragment that wants to use sys_tick_delta() passes in its |
| * own reference time variable, multiple code fragments can make use of this |
| * function concurrently. |
| * |
| * e.g. |
| * uint64_t reftime; |
| * (void) sys_tick_delta(&reftime); /# prime it #/ |
| * [do stuff] |
| * x = sys_tick_delta(&reftime); /# how long since priming #/ |
| * [do more stuff] |
| * y = sys_tick_delta(&reftime); /# how long since [do stuff] #/ |
| * |
| * @return tick count since reference time; undefined for first invocation |
| * |
| * NOTE: We use inline function for both 64-bit and 32-bit functions. |
| * Compiler optimizes out 64-bit result handling in 32-bit version. |
| */ |
| static ALWAYS_INLINE int64_t _nano_tick_delta(int64_t *reftime) |
| { |
| int64_t delta; |
| int64_t saved; |
| |
| /* |
| * Lock the interrupts when reading _sys_clock_tick_count 64-bit |
| * variable. Some architectures (x86) do not handle 64-bit atomically, |
| * so we have to lock the timer interrupt that causes change of |
| * _sys_clock_tick_count |
| */ |
| unsigned int imask = irq_lock(); |
| |
| saved = _sys_clock_tick_count; |
| irq_unlock(imask); |
| delta = saved - (*reftime); |
| *reftime = saved; |
| |
| return delta; |
| } |
| |
| /** |
| * |
| * @brief Return number of ticks since a reference time |
| * |
| * @return tick count since reference time; undefined for first invocation |
| */ |
| int64_t sys_tick_delta(int64_t *reftime) |
| { |
| return _nano_tick_delta(reftime); |
| } |
| |
| |
| uint32_t sys_tick_delta_32(int64_t *reftime) |
| { |
| return (uint32_t)_nano_tick_delta(reftime); |
| } |
| |
| int64_t k_uptime_delta(int64_t *reftime) |
| { |
| int64_t uptime, delta; |
| |
| uptime = k_uptime_get(); |
| delta = uptime - *reftime; |
| *reftime = uptime; |
| |
| return delta; |
| } |
| |
| uint32_t k_uptime_delta_32(int64_t *reftime) |
| { |
| return (uint32_t)k_uptime_delta(reftime); |
| } |
| |
| /* handle the expired timeouts in the nano timeout queue */ |
| |
| #ifdef CONFIG_SYS_CLOCK_EXISTS |
| #include <wait_q.h> |
| |
| /* |
| * Handle timeouts by dequeuing the expired ones from _timeout_q and queue |
| * them on a local one, then doing the real handling from that queue. This |
| * allows going through the second queue without needing to have the |
| * interrupts locked since it is a local queue. Each expired timeout is marked |
| * as _EXPIRED so that an ISR preempting us and releasing an object on which |
| * a thread was timing out and expiredwill not give the object to that thread. |
| * |
| * Always called from interrupt level, and always only from the system clock |
| * interrupt. |
| */ |
| |
| volatile int _handling_timeouts; |
| |
| static inline void handle_timeouts(int32_t ticks) |
| { |
| sys_dlist_t expired; |
| unsigned int key; |
| |
| /* init before locking interrupts */ |
| sys_dlist_init(&expired); |
| |
| key = irq_lock(); |
| |
| struct _timeout *head = |
| (struct _timeout *)sys_dlist_peek_head(&_timeout_q); |
| |
| K_DEBUG("head: %p, delta: %d\n", |
| head, head ? head->delta_ticks_from_prev : -2112); |
| |
| if (!head) { |
| irq_unlock(key); |
| return; |
| } |
| |
| head->delta_ticks_from_prev -= ticks; |
| |
| /* |
| * Dequeue all expired timeouts from _timeout_q, relieving irq lock |
| * pressure between each of them, allowing handling of higher priority |
| * interrupts. We know that no new timeout will be prepended in front |
| * of a timeout which delta is 0, since timeouts of 0 ticks are |
| * prohibited. |
| */ |
| sys_dnode_t *next = &head->node; |
| struct _timeout *timeout = (struct _timeout *)next; |
| |
| _handling_timeouts = 1; |
| |
| while (timeout && timeout->delta_ticks_from_prev == 0) { |
| |
| sys_dlist_remove(next); |
| sys_dlist_append(&expired, next); |
| timeout->delta_ticks_from_prev = _EXPIRED; |
| |
| irq_unlock(key); |
| key = irq_lock(); |
| |
| next = sys_dlist_peek_head(&_timeout_q); |
| timeout = (struct _timeout *)next; |
| } |
| |
| irq_unlock(key); |
| |
| _handle_expired_timeouts(&expired); |
| |
| _handling_timeouts = 0; |
| } |
| #else |
| #define handle_timeouts(ticks) do { } while ((0)) |
| #endif |
| |
| #ifdef CONFIG_TIMESLICING |
| int32_t _time_slice_elapsed; |
| int32_t _time_slice_duration = CONFIG_TIMESLICE_SIZE; |
| int _time_slice_prio_ceiling = CONFIG_TIMESLICE_PRIORITY; |
| |
| /* |
| * Always called from interrupt level, and always only from the system clock |
| * interrupt, thus: |
| * - _current does not have to be protected, since it only changes at thread |
| * level or when exiting a non-nested interrupt |
| * - _time_slice_elapsed does not have to be protected, since it can only change |
| * in this function and at thread level |
| * - _time_slice_duration does not have to be protected, since it can only |
| * change at thread level |
| */ |
| static void handle_time_slicing(int32_t ticks) |
| { |
| if (_time_slice_duration == 0) { |
| return; |
| } |
| |
| if (_is_prio_higher(_current->base.prio, _time_slice_prio_ceiling)) { |
| return; |
| } |
| |
| _time_slice_elapsed += _ticks_to_ms(ticks); |
| if (_time_slice_elapsed >= _time_slice_duration) { |
| |
| unsigned int key; |
| |
| _time_slice_elapsed = 0; |
| |
| key = irq_lock(); |
| _move_thread_to_end_of_prio_q(_current); |
| irq_unlock(key); |
| } |
| } |
| #else |
| #define handle_time_slicing(ticks) do { } while (0) |
| #endif |
| /** |
| * |
| * @brief Announce a tick to the kernel |
| * |
| * This function is only to be called by the system clock timer driver when a |
| * tick is to be announced to the kernel. It takes care of dequeuing the |
| * timers that have expired and wake up the threads pending on them. |
| * |
| * @return N/A |
| */ |
| void _nano_sys_clock_tick_announce(int32_t ticks) |
| { |
| unsigned int key; |
| |
| K_DEBUG("ticks: %d\n", ticks); |
| |
| /* 64-bit value, ensure atomic access with irq lock */ |
| key = irq_lock(); |
| _sys_clock_tick_count += ticks; |
| irq_unlock(key); |
| |
| handle_timeouts(ticks); |
| |
| /* time slicing is basically handled like just yet another timeout */ |
| handle_time_slicing(ticks); |
| } |