132 lines
2.6 KiB
C++
132 lines
2.6 KiB
C++
/*
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* \brief Timer for core
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* \author Martin stein
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* \date 2011-12-13
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*/
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/*
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* Copyright (C) 2011-2013 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 General Public License version 2.
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*/
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#ifndef _TIMER__CORTEX_A9_H_
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#define _TIMER__CORTEX_A9_H_
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/* Genode includes */
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#include <util/mmio.h>
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/* core includes */
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#include <cpu/cortex_a9.h>
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namespace Cortex_a9
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{
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/**
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* Timer for core
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*/
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class Timer : public Mmio
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{
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enum { TICS_PER_MS = Cortex_a9::Cpu::PRIVATE_TIMER_CLK / 1000, };
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/**
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* Load value register
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*/
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struct Load : Register<0x0, 32> { };
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/**
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* Timer counter value register
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*/
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struct Counter : Register<0x4, 32> { };
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/**
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* Timer control register
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*/
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struct Control : Register<0x8, 32>
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{
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struct Timer_enable : Bitfield<0,1> { }; /* enable counting */
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struct Auto_reload : Bitfield<1,1> { }; /* reload at zero */
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struct Irq_enable : Bitfield<2,1> { }; /* unmask interrupt */
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struct Prescaler : Bitfield<8,8> { }; /* modify frequency */
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/**
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* Configure for a one-shot
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*/
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static access_t init_one_shot()
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{
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return Timer_enable::bits(0) |
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Auto_reload::bits(0) |
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Irq_enable::bits(1) |
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Prescaler::bits(0);
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}
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};
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/**
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* Timer interrupt status register
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*/
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struct Interrupt_status : Register<0xc, 32>
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{
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struct Event : Bitfield<0,1> { }; /* if counter hit zero */
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};
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/**
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* Stop counting
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*/
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void _disable() { write<Control::Timer_enable>(0); }
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public:
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enum { IRQ = Cortex_a9::Cpu::PRIVATE_TIMER_IRQ };
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/**
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* Constructor, clears the interrupt output
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*/
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Timer() : Mmio(Cortex_a9::Cpu::PRIVATE_TIMER_MMIO_BASE)
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{
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_disable();
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clear_interrupt();
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}
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/**
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* Start a one-shot run
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* \param tics native timer value used to assess the delay
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* of the timer interrupt as of the call
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*/
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inline void start_one_shot(uint32_t const tics)
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{
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/* reset timer */
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clear_interrupt();
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write<Control>(Control::init_one_shot());
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/* load timer and start decrementing */
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write<Load>(tics);
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write<Control::Timer_enable>(1);
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}
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/**
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* Translate milliseconds to a native timer value
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*/
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static uint32_t ms_to_tics(unsigned const ms) {
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return ms * TICS_PER_MS; }
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/**
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* Stop the timer and return last timer value
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*/
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unsigned stop_one_shot()
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{
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unsigned const v = read<Counter>();
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_disable();
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return v;
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}
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/**
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* Clear interrupt output line
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*/
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void clear_interrupt() {
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write<Interrupt_status::Event>(1); }
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};
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}
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#endif /* _TIMER__CORTEX_A9_H_ */
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