167 lines
4.4 KiB
C
167 lines
4.4 KiB
C
/*
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* Copyright (c) 2017-2019 Oticon A/S
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/**
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* Driver for the timer model of the POSIX native_posix board
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* It provides the interfaces required by the kernel and the sanity testcases
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* It also provides a custom k_busy_wait() which can be used with the
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* POSIX arch and InfClock SOC
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*/
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#include "zephyr/types.h"
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#include "irq.h"
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#include "device.h"
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#include <drivers/timer/system_timer.h>
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#include "sys_clock.h"
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#include "timer_model.h"
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#include "soc.h"
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#include <arch/posix/posix_trace.h>
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static uint64_t tick_period; /* System tick period in microseconds */
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/* Time (microseconds since boot) of the last timer tick interrupt */
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static uint64_t last_tick_time;
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/**
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* Return the current HW cycle counter
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* (number of microseconds since boot in 32bits)
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*/
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uint32_t z_timer_cycle_get_32(void)
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{
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return hwm_get_time();
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}
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/**
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* Interrupt handler for the timer interrupt
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* Announce to the kernel that a number of ticks have passed
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*/
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static void np_timer_isr(const void *arg)
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{
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ARG_UNUSED(arg);
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uint64_t now = hwm_get_time();
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int32_t elapsed_ticks = (now - last_tick_time)/tick_period;
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last_tick_time += elapsed_ticks*tick_period;
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z_clock_announce(elapsed_ticks);
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}
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/*
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* @brief Initialize system timer driver
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*
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* Enable the hw timer, setting its tick period, and setup its interrupt
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*/
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int z_clock_driver_init(const struct device *device)
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{
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ARG_UNUSED(device);
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tick_period = 1000000ul / CONFIG_SYS_CLOCK_TICKS_PER_SEC;
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last_tick_time = hwm_get_time();
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hwtimer_enable(tick_period);
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IRQ_CONNECT(TIMER_TICK_IRQ, 1, np_timer_isr, 0, 0);
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irq_enable(TIMER_TICK_IRQ);
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return 0;
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}
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/**
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* @brief Set system clock timeout
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*
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* Informs the system clock driver that the next needed call to
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* z_clock_announce() will not be until the specified number of ticks
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* from the the current time have elapsed.
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*
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* See system_timer.h for more information
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*
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* @param ticks Timeout in tick units
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* @param idle Hint to the driver that the system is about to enter
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* the idle state immediately after setting the timeout
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*/
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void z_clock_set_timeout(int32_t ticks, bool idle)
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{
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ARG_UNUSED(idle);
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#if defined(CONFIG_TICKLESS_KERNEL)
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uint64_t silent_ticks;
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/* Note that we treat INT_MAX literally as anyhow the maximum amount of
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* ticks we can report with z_clock_announce() is INT_MAX
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*/
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if (ticks == K_TICKS_FOREVER) {
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silent_ticks = INT64_MAX;
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} else if (ticks > 0) {
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silent_ticks = ticks - 1;
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} else {
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silent_ticks = 0;
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}
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hwtimer_set_silent_ticks(silent_ticks);
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#endif
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}
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/**
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* @brief Ticks elapsed since last z_clock_announce() call
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*
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* Queries the clock driver for the current time elapsed since the
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* last call to z_clock_announce() was made. The kernel will call
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* this with appropriate locking, the driver needs only provide an
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* instantaneous answer.
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*/
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uint32_t z_clock_elapsed(void)
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{
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return (hwm_get_time() - last_tick_time)/tick_period;
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}
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#if defined(CONFIG_ARCH_HAS_CUSTOM_BUSY_WAIT)
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/**
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* Replacement to the kernel k_busy_wait()
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* Will block this thread (and therefore the whole zephyr) during usec_to_wait
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*
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* Note that interrupts may be received in the meanwhile and that therefore this
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* thread may loose context
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*
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* This special arch_busy_wait() is necessary due to how the POSIX arch/SOC INF
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* models a CPU. Conceptually it could be thought as if the MCU was running
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* at an infinitely high clock, and therefore no simulated time passes while
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* executing instructions(*1).
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* Therefore to be able to busy wait this function does the equivalent of
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* programming a dedicated timer which will raise a non-maskable interrupt,
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* and halting the CPU.
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*
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* (*1) In reality simulated time is simply not advanced just due to the "MCU"
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* running. Meaning, the SW running on the MCU is assumed to take 0 time.
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*/
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void arch_busy_wait(uint32_t usec_to_wait)
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{
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uint64_t time_end = hwm_get_time() + usec_to_wait;
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while (hwm_get_time() < time_end) {
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/*
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* There may be wakes due to other interrupts including
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* other threads calling arch_busy_wait
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*/
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hwtimer_wake_in_time(time_end);
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posix_halt_cpu();
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}
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}
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#endif
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#if defined(CONFIG_SYSTEM_CLOCK_DISABLE)
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/**
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*
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* @brief Stop announcing sys ticks into the kernel
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*
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* Disable the system ticks generation
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*
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* @return N/A
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*/
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void sys_clock_disable(void)
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{
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irq_disable(TIMER_TICK_IRQ);
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hwtimer_set_silent_ticks(INT64_MAX);
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}
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#endif /* CONFIG_SYSTEM_CLOCK_DISABLE */
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