104 lines
2.6 KiB
C++
104 lines
2.6 KiB
C++
/*
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* \brief Time source that uses the Programmable Interval Timer (PIT)
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* \author Norman Feske
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* \author Martin Stein
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* \date 2009-06-16
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*/
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/*
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* Copyright (C) 2009-2017 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 <io_port_session/connection.h>
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#include <irq_session/connection.h>
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#include <base/duration.h>
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/* local includes */
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#include <signalled_time_source.h>
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namespace Timer {
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using Genode::uint64_t;
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using Microseconds = Genode::Microseconds;
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using Duration = Genode::Duration;
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class Time_source;
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}
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class Timer::Time_source : public Genode::Signalled_time_source
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{
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private:
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enum {
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PIT_TICKS_PER_SECOND = 1193182,
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PIT_TICKS_PER_MSEC = PIT_TICKS_PER_SECOND/1000,
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PIT_MAX_COUNT = 65535,
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PIT_DATA_PORT_0 = 0x40, /* data port for PIT channel 0,
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connected to the PIC */
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PIT_CMD_PORT = 0x43, /* PIT command port */
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PIT_MAX_USEC = (PIT_MAX_COUNT*1000)/(PIT_TICKS_PER_MSEC),
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IRQ_PIT = 0, /* timer interrupt at the PIC */
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/*
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* Bit definitions for accessing the PIT command port
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*/
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PIT_CMD_SELECT_CHANNEL_0 = 0 << 6,
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PIT_CMD_ACCESS_LO = 1 << 4,
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PIT_CMD_ACCESS_LO_HI = 3 << 4,
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PIT_CMD_MODE_IRQ = 0 << 1,
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PIT_CMD_MODE_RATE = 2 << 1,
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PIT_CMD_READ_BACK = 3 << 6,
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PIT_CMD_RB_COUNT = 0 << 5,
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PIT_CMD_RB_STATUS = 0 << 4,
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PIT_CMD_RB_CHANNEL_0 = 1 << 1,
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/*
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* Bit definitions of the PIT status byte
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*/
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PIT_STAT_INT_LINE = 1 << 7,
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};
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Genode::Io_port_connection _io_port;
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Genode::Irq_connection _timer_irq;
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uint64_t mutable _curr_time_us = 0;
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Genode::uint16_t mutable _counter_init_value = 0;
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bool mutable _handled_wrap = false;
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void _set_counter(Genode::uint16_t value);
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Genode::uint16_t _read_counter(bool *wrapped);
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Genode::uint32_t _ticks_since_update_one_wrap(Genode::uint16_t curr_counter);
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Genode::uint32_t _ticks_since_update_no_wrap(Genode::uint16_t curr_counter);
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Duration _curr_time();
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public:
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Time_source(Genode::Env &env);
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/*************************
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** Genode::Time_source **
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*************************/
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Duration curr_time() override;
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void schedule_timeout(Microseconds duration, Timeout_handler &handler) override;
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Microseconds max_timeout() const override {
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return Microseconds(PIT_MAX_USEC); }
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};
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#endif /* _TIME_SOURCE_H_ */
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