109 lines
2.5 KiB
C++
109 lines
2.5 KiB
C++
/*
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* \brief Time source using Nova timed semaphore down
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* \author Alexander Boettcher
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* \author Martin Stein
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* \date 2014-06-24
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*/
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/*
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* Copyright (C) 2014-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _TIME_SOURCE_H_
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#define _TIME_SOURCE_H_
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/* Genode includes */
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#include <trace/timestamp.h>
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#include <base/attached_rom_dataspace.h>
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/* local includes */
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#include <threaded_time_source.h>
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namespace Timer { class Time_source; }
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class Timer::Time_source : public Threaded_time_source
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{
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private:
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/* read the tsc frequency from platform info */
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static unsigned long _obtain_tsc_khz(Genode::Env &env)
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{
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try {
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Genode::Attached_rom_dataspace info { env, "platform_info"};
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return info.xml()
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.sub_node("hardware")
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.sub_node("tsc")
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.attribute_value("freq_khz", 0UL);
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} catch (...) { }
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return 0;
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}
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Genode::addr_t _sem { ~0UL };
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unsigned long _timeout_us { 0 };
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unsigned long const _tsc_khz;
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Duration _curr_time { Microseconds(0) };
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Genode::Trace::Timestamp _tsc_start { Genode::Trace::timestamp() };
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Genode::Trace::Timestamp _tsc_last { _tsc_start };
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/* 1 / ((us / (1000 * 1000)) * (tsc_khz * 1000)) */
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enum { TSC_FACTOR = 1000ULL };
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inline Genode::uint64_t _tsc_to_us(Genode::uint64_t tsc) const
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{
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return (tsc) / (_tsc_khz / TSC_FACTOR);
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}
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/**************************
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** Threaded_time_source **
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**************************/
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void _wait_for_irq() override;
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public:
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Time_source(Genode::Env &env)
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:
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Threaded_time_source(env), _tsc_khz(_obtain_tsc_khz(env))
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{
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start();
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}
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/*************************
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** Genode::Time_source **
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*************************/
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void schedule_timeout(Microseconds duration,
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Timeout_handler &handler) override;
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Microseconds max_timeout() const override
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{
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unsigned long long const max_us_ull = _tsc_to_us(~0ULL);
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return max_us_ull > ~0UL ? Microseconds(~0UL) : Microseconds(max_us_ull);
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}
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Duration curr_time() override
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{
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using namespace Genode::Trace;
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Timestamp const curr_tsc = timestamp();
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Microseconds const diff(_tsc_to_us(curr_tsc - _tsc_last));
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/* update in irq context or if update rate is below 4000 irq/s */
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if (_irq || diff.value > 250) {
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_curr_time.add(diff);
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_tsc_last = curr_tsc;
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}
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return _curr_time;
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}
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};
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#endif /* _TIME_SOURCE_H_ */
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