63 lines
1.5 KiB
C
63 lines
1.5 KiB
C
/*
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* Copyright (c) 2018 Intel Corporation
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/kernel.h>
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#include <zephyr/drivers/timer/system_timer.h>
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#include <zephyr/sys_clock.h>
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#include <kernel_arch_interface.h>
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void z_impl_k_busy_wait(uint32_t usec_to_wait)
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{
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SYS_PORT_TRACING_FUNC_ENTER(k_thread, busy_wait, usec_to_wait);
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if (usec_to_wait == 0U) {
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SYS_PORT_TRACING_FUNC_EXIT(k_thread, busy_wait, usec_to_wait);
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return;
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}
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#if defined(CONFIG_ARCH_HAS_CUSTOM_BUSY_WAIT)
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arch_busy_wait(usec_to_wait);
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#elif defined(CONFIG_SYS_CLOCK_EXISTS)
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uint32_t start_cycles = k_cycle_get_32();
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/* use 64-bit math to prevent overflow when multiplying */
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uint32_t cycles_to_wait = (uint32_t)(
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(uint64_t)usec_to_wait *
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(uint64_t)sys_clock_hw_cycles_per_sec() /
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(uint64_t)USEC_PER_SEC
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);
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for (;;) {
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uint32_t current_cycles = k_cycle_get_32();
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/* this handles the rollover on an unsigned 32-bit value */
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if ((current_cycles - start_cycles) >= cycles_to_wait) {
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break;
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}
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}
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#else
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/*
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* Crude busy loop for the purpose of being able to configure out
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* system timer support.
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*/
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unsigned int loops_per_usec = CONFIG_BUSYWAIT_CPU_LOOPS_PER_USEC;
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unsigned int loops = loops_per_usec * usec_to_wait;
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while (loops-- > 0) {
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arch_nop();
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}
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#endif
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SYS_PORT_TRACING_FUNC_EXIT(k_thread, busy_wait, usec_to_wait);
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}
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#ifdef CONFIG_USERSPACE
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static inline void z_vrfy_k_busy_wait(uint32_t usec_to_wait)
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{
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z_impl_k_busy_wait(usec_to_wait);
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}
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#include <syscalls/k_busy_wait_mrsh.c>
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#endif /* CONFIG_USERSPACE */
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