113 lines
2.7 KiB
C++
113 lines
2.7 KiB
C++
/*
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* \brief Driver base for the private timer of the ARM Cortex-A9
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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) 2011-2012 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 _INCLUDE__DRIVERS__CPU__CORTEX_A9__TIMER_H_
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#define _INCLUDE__DRIVERS__CPU__CORTEX_A9__TIMER_H_
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/* Genode includes */
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#include <util/mmio.h>
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namespace Genode
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{
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/**
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* Driver base for the private timer of the ARM Cortex-A9
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*/
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template <unsigned long CLK>
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struct Cortex_a9_timer : public Mmio
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{
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enum { TICS_PER_MS = 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> { }; /* 1: 'Counter' decrements, 0: 'Counter' stays 0 */
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struct Auto_reload : Bitfield<1,1> { }; /* 1: Auto reload mode, 0: One shot mode */
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struct Irq_enable : Bitfield<2,1> { }; /* 1: IRQ = 'Interrupt_status::Event' 0: IRQ = 0 */
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struct Prescaler : Bitfield<8,8> { }; /* modifies the clock period for the decrementing */
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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> { }; /* 'Event' = !'Counter' */
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};
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/**
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* Constructor, clears the interrupt output
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*/
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Cortex_a9_timer(addr_t const mmio_base) : Mmio(mmio_base) {
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clear_interrupt(); }
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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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* Translate milliseconds to a native timer value
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*/
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static uint32_t ms_to_tics(unsigned long 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 long stop()
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{
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unsigned long const v = read<Counter>();
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write<typename Control::Timer_enable>(0);
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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() { write<typename Interrupt_status::Event>(1); }
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};
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}
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template <unsigned long CLOCK>
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void Genode::Cortex_a9_timer<CLOCK>::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::Timer_enable::bits(0) |
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Control::Auto_reload::bits(0) |
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Control::Irq_enable::bits(1) |
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Control::Prescaler::bits(0));
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/* load timer and start decrementing */
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write<Load>(tics);
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write<typename Control::Timer_enable>(1);
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}
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#endif /* _INCLUDE__DRIVERS__CPU__CORTEX_A9__TIMER_H_ */
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