src/dev/arm/generic_timer.hh - public/gem5 - Git at Google

 /*
  * Copyright (c) 2013, 2015, 2017-2018,2020 ARM Limited
  * All rights reserved.
  *
  * The license below extends only to copyright in the software and shall
  * not be construed as granting a license to any other intellectual
  * property including but not limited to intellectual property relating
  * to a hardware implementation of the functionality of the software
  * licensed hereunder.  You may use the software subject to the license
  * terms below provided that you ensure that this notice is replicated
  * unmodified and in its entirety in all distributions of the software,
  * modified or unmodified, in source code or in binary form.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met: redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer;
  * redistributions in binary form must reproduce the above copyright
  * notice, this list of conditions and the following disclaimer in the
  * documentation and/or other materials provided with the distribution;
  * neither the name of the copyright holders nor the names of its
  * contributors may be used to endorse or promote products derived from
  * this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #ifndef __DEV_ARM_GENERIC_TIMER_HH__
 #define __DEV_ARM_GENERIC_TIMER_HH__

 #include <cstdint>
 #include <vector>

 #include "arch/arm/isa_device.hh"
 #include "arch/arm/system.hh"
 #include "base/addr_range.hh"
 #include "base/bitunion.hh"
 #include "base/types.hh"
 #include "dev/arm/base_gic.hh"
 #include "dev/arm/generic_timer_miscregs_types.hh"
 #include "sim/core.hh"
 #include "sim/drain.hh"
 #include "sim/eventq.hh"
 #include "sim/serialize.hh"
 #include "sim/sim_object.hh"

 /// @file
 /// This module implements the global system counter and the local per-CPU
 /// architected timers as specified by the ARM Generic Timer extension:
 /// Arm ARM (ARM DDI 0487E.a)
 ///     D11.1.2 - The system counter
 ///     D11.2 - The AArch64 view of the Generic Timer
 ///     G6.2  - The AArch32 view of the Generic Timer
 ///     I2 - System Level Implementation of the Generic Timer

 class Checkpoint;
 struct SystemCounterParams;
 struct GenericTimerParams;
 struct GenericTimerFrameParams;
 struct GenericTimerMemParams;

 /// Abstract class for elements whose events depend on the counting speed
 /// of the System Counter
 class SystemCounterListener
 {
   public:
     /// Called from the SystemCounter when a change in counting speed occurred
     /// Events should be rescheduled properly inside this member function
     virtual void notify(void) = 0;
 };

 /// Global system counter.  It is shared by the architected and memory-mapped
 /// timers.
 class SystemCounter : public SimObject
 {
   protected:
     /// Indicates if the counter is enabled
     bool _enabled;
     /// Counter frequency (as specified by CNTFRQ).
     uint32_t _freq;
     /// Counter value (as specified in CNTCV).
     uint64_t _value;
     /// Value increment in each counter cycle
     uint64_t _increment;
     /// Frequency modes table with all possible frequencies for the counter
     std::vector<uint32_t> _freqTable;
     /// Currently selected entry in the table, its contents should match _freq
     size_t _activeFreqEntry;
     /// Cached copy of the counter period (inverse of the frequency).
     Tick _period;
     /// Counter cycle start Tick when the counter status affecting
     /// its value has been updated
     Tick _updateTick;

     /// Listeners to changes in counting speed
     std::vector<SystemCounterListener *> _listeners;

     /// Maximum architectural number of frequency table entries
     static constexpr size_t MAX_FREQ_ENTRIES = 1004;

   public:
     SystemCounter(const SystemCounterParams &p);

     /// Validates a System Counter reference
     /// @param sys_cnt System counter reference to validate
     static void validateCounterRef(SystemCounter *sys_cnt);

     /// Indicates if the counter is enabled.
     bool enabled() const { return _enabled; }
     /// Returns the counter frequency.
     uint32_t freq() const { return _freq; }
     /// Updates and returns the counter value.
     uint64_t value();
     /// Returns the value increment
     uint64_t increment() const { return _increment; }
     /// Returns a reference to the frequency modes table.
     std::vector<uint32_t>& freqTable() { return _freqTable; }
     /// Returns the currently active frequency table entry.
     size_t activeFreqEntry() const { return _activeFreqEntry; }
     /// Returns the counter period.
     Tick period() const { return _period; }

     /// Enables the counter after a CNTCR.EN == 1
     void enable();
     /// Disables the counter after a CNTCR.EN == 0
     void disable();

     /// Schedules a counter frequency update after a CNTCR.FCREQ == 1
     /// This complies with frequency transitions as per the architecture
     /// @param new_freq_entry Index in CNTFID of the new freq
     void freqUpdateSchedule(size_t new_freq_entry);

     /// Sets the value explicitly from writes to CNTCR.CNTCV
     void setValue(uint64_t new_value);

     /// Called from System Counter Listeners to register
     void registerListener(SystemCounterListener *listener);

     /// Returns the tick at which a certain counter value is reached
     Tick whenValue(uint64_t target_val);
     Tick whenValue(uint64_t cur_val, uint64_t target_val) const;

     void serialize(CheckpointOut &cp) const override;
     void unserialize(CheckpointIn &cp) override;

   private:
     // Disable copying
     SystemCounter(const SystemCounter &c);

     /// Frequency update event handling
     EventFunctionWrapper _freqUpdateEvent;
     size_t _nextFreqEntry;
     /// Callback for the frequency update
     void freqUpdateCallback();

     /// Updates the counter value.
     void updateValue(void);

     /// Updates the update tick, normalizes to the lower cycle start tick
     void updateTick(void);

     /// Notifies counting speed changes to listeners
     void notifyListeners(void) const;
 };

 /// Per-CPU architected timer.
 class ArchTimer : public SystemCounterListener, public Drainable,
                   public Serializable
 {
   protected:
     /// Control register.
     BitUnion32(ArchTimerCtrl)
     Bitfield<0> enable;
     Bitfield<1> imask;
     Bitfield<2> istatus;
     EndBitUnion(ArchTimerCtrl)

     /// Name of this timer.
     const std::string _name;

     /// Pointer to parent class.
     SimObject &_parent;

     SystemCounter &_systemCounter;

     ArmInterruptPin * const _interrupt;

     /// Value of the control register ({CNTP/CNTHP/CNTV}_CTL).
     ArchTimerCtrl _control;
     /// Programmed limit value for the upcounter ({CNTP/CNTHP/CNTV}_CVAL).
     uint64_t _counterLimit;
     /// Offset relative to the physical timer (CNTVOFF)
     uint64_t _offset;

     /**
      * Timer settings or the offset has changed, re-evaluate
      * trigger condition and raise interrupt if necessary.
      */
     void updateCounter();

     /// Called when the upcounter reaches the programmed value.
     void counterLimitReached();
     EventFunctionWrapper _counterLimitReachedEvent;

     virtual bool scheduleEvents() { return true; }

   public:
     ArchTimer(const std::string &name,
               SimObject &parent,
               SystemCounter &sysctr,
               ArmInterruptPin *interrupt);

     /// Returns the timer name.
     std::string name() const { return _name; }

     /// Returns the CompareValue view of the timer.
     uint64_t compareValue() const { return _counterLimit; }
     /// Sets the CompareValue view of the timer.
     void setCompareValue(uint64_t val);

     /// Returns the TimerValue view of the timer.
     uint32_t timerValue() const { return _counterLimit - value(); }
     /// Sets the TimerValue view of the timer.
     void setTimerValue(uint32_t val);

     /// Sets the control register.
     uint32_t control() const { return _control; }
     void setControl(uint32_t val);

     uint64_t offset() const { return _offset; }
     void setOffset(uint64_t val);

     /// Returns the value of the counter which this timer relies on.
     uint64_t value() const;
     Tick whenValue(uint64_t target_val) {
         return _systemCounter.whenValue(value(), target_val);
     }

     void notify(void) override;

     // Serializable
     void serialize(CheckpointOut &cp) const override;
     void unserialize(CheckpointIn &cp) override;

     // Drainable
     DrainState drain() override;
     void drainResume() override;

   private:
     // Disable copying
     ArchTimer(const ArchTimer &t);
 };

 class ArchTimerKvm : public ArchTimer
 {
   private:
     ArmSystem &system;

   public:
     ArchTimerKvm(const std::string &name,
                  ArmSystem &system,
                  SimObject &parent,
                  SystemCounter &sysctr,
                  ArmInterruptPin *interrupt)
       : ArchTimer(name, parent, sysctr, interrupt), system(system) {}

   protected:
     // For ArchTimer's in a GenericTimerISA with Kvm execution about
     // to begin, skip rescheduling the event.
     // Otherwise, we should reschedule the event (if necessary).
     bool scheduleEvents() override {
         return !system.validKvmEnvironment();
     }
 };

 class GenericTimer : public SimObject
 {
   public:
     PARAMS(GenericTimer);

     GenericTimer(const Params &p);

     void serialize(CheckpointOut &cp) const override;
     void unserialize(CheckpointIn &cp) override;

   public:
     void setMiscReg(int misc_reg, unsigned cpu, RegVal val);
     RegVal readMiscReg(int misc_reg, unsigned cpu);

   protected:
     class CoreTimers : public SystemCounterListener, public Serializable
     {
       public:
         CoreTimers(GenericTimer &_parent, ArmSystem &system, unsigned cpu,
                    ArmInterruptPin *_irqPhysS, ArmInterruptPin *_irqPhysNS,
                    ArmInterruptPin *_irqVirt, ArmInterruptPin *_irqHyp);

         /// Generic Timer parent reference
         GenericTimer &parent;

         /// System counter frequency as visible from this core
         uint32_t cntfrq;

         /// Kernel control register
         ArmISA::CNTKCTL cntkctl;

         /// Hypervisor control register
         ArmISA::CNTHCTL cnthctl;

         /// Thread (HW) context associated to this PE implementation
         ThreadContext *threadContext;

         ArmInterruptPin const *irqPhysS;
         ArmInterruptPin const *irqPhysNS;
         ArmInterruptPin const *irqVirt;
         ArmInterruptPin const *irqHyp;

         ArchTimerKvm physS;
         ArchTimerKvm physNS;
         ArchTimerKvm virt;
         ArchTimerKvm hyp;

         // Event Stream. Events are generated based on a configurable
         // transitionBit over the counter value. transitionTo indicates
         // the transition direction (0->1 or 1->0)
         struct EventStream
         {
             EventFunctionWrapper event;
             uint8_t transitionTo;
             uint8_t transitionBit;

             uint64_t
             eventTargetValue(uint64_t val) const
             {
                 uint64_t bit_val = bits(val, transitionBit);
                 uint64_t ret_val = mbits(val, 63, transitionBit);
                 uint64_t incr_val = 1 << transitionBit;
                 if (bit_val == transitionTo)
                     incr_val *= 2;
                 return ret_val + incr_val;
             }
         };

         EventStream physEvStream;
         EventStream virtEvStream;
         void physEventStreamCallback();
         void virtEventStreamCallback();
         void eventStreamCallback() const;
         void schedNextEvent(EventStream &ev_stream, ArchTimer &timer);

         void notify(void) override;

         void serialize(CheckpointOut &cp) const override;
         void unserialize(CheckpointIn &cp) override;

       private:
         // Disable copying
         CoreTimers(const CoreTimers &c);
     };

     CoreTimers &getTimers(int cpu_id);
     void createTimers(unsigned cpus);

     /// System counter reference.
     SystemCounter &systemCounter;

     /// Per-CPU physical architected timers.
     std::vector<std::unique_ptr<CoreTimers>> timers;

   protected: // Configuration
     /// ARM system containing this timer
     ArmSystem &system;

     void handleStream(CoreTimers::EventStream *ev_stream,
         ArchTimer *timer, RegVal old_cnt_ctl, RegVal cnt_ctl);
 };

 class GenericTimerISA : public ArmISA::BaseISADevice
 {
   public:
     GenericTimerISA(GenericTimer &_parent, unsigned _cpu)
         : parent(_parent), cpu(_cpu) {}

     void setMiscReg(int misc_reg, RegVal val) override;
     RegVal readMiscReg(int misc_reg) override;

   protected:
     GenericTimer &parent;
     unsigned cpu;
 };

 class GenericTimerFrame : public PioDevice
 {
   public:
     GenericTimerFrame(const GenericTimerFrameParams &p);

     void serialize(CheckpointOut &cp) const override;
     void unserialize(CheckpointIn &cp) override;

     /// Indicates if this frame implements a virtual timer
     bool hasVirtualTimer() const;

     /// Returns the virtual offset for this frame if a virtual timer is
     /// implemented
     uint64_t getVirtOffset() const;

     /// Sets the virtual offset for this frame's virtual timer after
     /// a write to CNTVOFF
     void setVirtOffset(uint64_t new_offset);

     /// Indicates if this frame implements a second EL0 view
     bool hasEl0View() const;

     /// Returns the access bits for this frame
     uint8_t getAccessBits() const;

     /// Updates the access bits after a write to CNTCTLBase.CNTACR
     void setAccessBits(uint8_t data);

     /// Indicates if non-secure accesses are allowed to this frame
     bool hasNonSecureAccess() const;

     /// Allows non-secure accesses after an enabling write to
     /// CNTCTLBase.CNTNSAR
     void setNonSecureAccess();

     /// Indicates if CNTVOFF is readable for this frame
     bool hasReadableVoff() const;

   protected:
     AddrRangeList getAddrRanges() const override;
     Tick read(PacketPtr pkt) override;
     Tick write(PacketPtr pkt) override;

   private:
     /// CNTBase/CNTEL0Base (Memory-mapped timer frame)
     uint64_t timerRead(Addr addr, size_t size, bool is_sec, bool to_el0) const;
     void timerWrite(Addr addr, size_t size, uint64_t data, bool is_sec,
                     bool to_el0);
     const AddrRange timerRange;
     AddrRange timerEl0Range;

     static const Addr TIMER_CNTPCT_LO          = 0x00;
     static const Addr TIMER_CNTPCT_HI          = 0x04;
     static const Addr TIMER_CNTVCT_LO          = 0x08;
     static const Addr TIMER_CNTVCT_HI          = 0x0c;
     static const Addr TIMER_CNTFRQ             = 0x10;
     static const Addr TIMER_CNTEL0ACR          = 0x14;
     static const Addr TIMER_CNTVOFF_LO         = 0x18;
     static const Addr TIMER_CNTVOFF_HI         = 0x1c;
     static const Addr TIMER_CNTP_CVAL_LO       = 0x20;
     static const Addr TIMER_CNTP_CVAL_HI       = 0x24;
     static const Addr TIMER_CNTP_TVAL          = 0x28;
     static const Addr TIMER_CNTP_CTL           = 0x2c;
     static const Addr TIMER_CNTV_CVAL_LO       = 0x30;
     static const Addr TIMER_CNTV_CVAL_HI       = 0x34;
     static const Addr TIMER_CNTV_TVAL          = 0x38;
     static const Addr TIMER_CNTV_CTL           = 0x3c;

     /// All MMIO ranges GenericTimerFrame responds to
     AddrRangeList addrRanges;

     /// System counter reference.
     SystemCounter &systemCounter;

     /// Physical and virtual timers
     ArchTimer physTimer;
     ArchTimer virtTimer;

     /// Reports access properties of the CNTBase register frame elements
     BitUnion8(AccessBits)
         Bitfield<5> rwpt;
         Bitfield<4> rwvt;
         Bitfield<3> rvoff;
         Bitfield<2> rfrq;
         Bitfield<1> rvct;
         Bitfield<0> rpct;
     EndBitUnion(AccessBits)
     AccessBits accessBits;

     // Reports access properties of the CNTEL0Base register frame elements
     BitUnion16(AccessBitsEl0)
         Bitfield<9> pten;
         Bitfield<8> vten;
         Bitfield<1> vcten;
         Bitfield<0> pcten;
     EndBitUnion(AccessBitsEl0)
     AccessBitsEl0 accessBitsEl0;

     /// Reports whether non-secure accesses are allowed to this frame
     bool nonSecureAccess;

     ArmSystem &system;
 };

 class GenericTimerMem : public PioDevice
 {
   public:
     GenericTimerMem(const GenericTimerMemParams &p);

     /// Validates a Generic Timer register frame address range
     /// @param base_addr Range of the register frame
     static void validateFrameRange(const AddrRange &range);

     /// Validates an MMIO access permissions
     /// @param sys System reference where the acces is being made
     /// @param is_sec If the access is to secure memory
     static bool validateAccessPerm(ArmSystem &sys, bool is_sec);

   protected:
     AddrRangeList getAddrRanges() const override;
     Tick read(PacketPtr pkt) override;
     Tick write(PacketPtr pkt) override;

   private:
     /// CNTControlBase (System counter control frame)
     uint64_t counterCtrlRead(Addr addr, size_t size, bool is_sec) const;
     void counterCtrlWrite(Addr addr, size_t size, uint64_t data, bool is_sec);
     const AddrRange counterCtrlRange;

     BitUnion32(CNTCR)
         Bitfield<17,8> fcreq;
         Bitfield<2> scen;
         Bitfield<1> hdbg;
         Bitfield<0> en;
     EndBitUnion(CNTCR)

     BitUnion32(CNTSR)
         Bitfield<31,8> fcack;
     EndBitUnion(CNTSR)

     static const Addr COUNTER_CTRL_CNTCR       = 0x00;
     static const Addr COUNTER_CTRL_CNTSR       = 0x04;
     static const Addr COUNTER_CTRL_CNTCV_LO    = 0x08;
     static const Addr COUNTER_CTRL_CNTCV_HI    = 0x0c;
     static const Addr COUNTER_CTRL_CNTSCR      = 0x10;
     static const Addr COUNTER_CTRL_CNTID       = 0x1c;
     static const Addr COUNTER_CTRL_CNTFID      = 0x20;

     /// CNTReadBase (System counter status frame)
     uint64_t counterStatusRead(Addr addr, size_t size) const;
     void counterStatusWrite(Addr addr, size_t size, uint64_t data);
     const AddrRange counterStatusRange;

     static const Addr COUNTER_STATUS_CNTCV_LO  = 0x00;
     static const Addr COUNTER_STATUS_CNTCV_HI  = 0x04;

     /// CNTCTLBase (Memory-mapped timer global control frame)
     uint64_t timerCtrlRead(Addr addr, size_t size, bool is_sec) const;
     void timerCtrlWrite(Addr addr, size_t size, uint64_t data, bool is_sec);
     const AddrRange timerCtrlRange;

     /// ID register for reporting features of implemented timer frames
     uint32_t cnttidr;

     static const Addr TIMER_CTRL_CNTFRQ        = 0x00;
     static const Addr TIMER_CTRL_CNTNSAR       = 0x04;
     static const Addr TIMER_CTRL_CNTTIDR       = 0x08;
     static const Addr TIMER_CTRL_CNTACR        = 0x40;
     static const Addr TIMER_CTRL_CNTVOFF_LO    = 0x80;
     static const Addr TIMER_CTRL_CNTVOFF_HI    = 0x84;

     /// All MMIO ranges GenericTimerMem responds to
     const AddrRangeList addrRanges;

     /// System counter reference.
     SystemCounter &systemCounter;

     /// Maximum architectural number of memory-mapped timer frames
     static constexpr size_t MAX_TIMER_FRAMES = 8;

     /// Timer frame references
     std::vector<GenericTimerFrame *> frames;

     ArmSystem &system;
 };

 #endif // __DEV_ARM_GENERIC_TIMER_HH__
	/*
	* Copyright (c) 2013, 2015, 2017-2018,2020 ARM Limited
	* All rights reserved.
	*
	* The license below extends only to copyright in the software and shall
	* not be construed as granting a license to any other intellectual
	* property including but not limited to intellectual property relating
	* to a hardware implementation of the functionality of the software
	* licensed hereunder. You may use the software subject to the license
	* terms below provided that you ensure that this notice is replicated
	* unmodified and in its entirety in all distributions of the software,
	* modified or unmodified, in source code or in binary form.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are
	* met: redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer;
	* redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution;
	* neither the name of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#ifndef __DEV_ARM_GENERIC_TIMER_HH__
	#define __DEV_ARM_GENERIC_TIMER_HH__

	#include <cstdint>
	#include <vector>

	#include "arch/arm/isa_device.hh"
	#include "arch/arm/system.hh"
	#include "base/addr_range.hh"
	#include "base/bitunion.hh"
	#include "base/types.hh"
	#include "dev/arm/base_gic.hh"
	#include "dev/arm/generic_timer_miscregs_types.hh"
	#include "sim/core.hh"
	#include "sim/drain.hh"
	#include "sim/eventq.hh"
	#include "sim/serialize.hh"
	#include "sim/sim_object.hh"

	/// @file
	/// This module implements the global system counter and the local per-CPU
	/// architected timers as specified by the ARM Generic Timer extension:
	/// Arm ARM (ARM DDI 0487E.a)
	/// D11.1.2 - The system counter
	/// D11.2 - The AArch64 view of the Generic Timer
	/// G6.2 - The AArch32 view of the Generic Timer
	/// I2 - System Level Implementation of the Generic Timer

	class Checkpoint;
	struct SystemCounterParams;
	struct GenericTimerParams;
	struct GenericTimerFrameParams;
	struct GenericTimerMemParams;

	/// Abstract class for elements whose events depend on the counting speed
	/// of the System Counter
	class SystemCounterListener
	{
	public:
	/// Called from the SystemCounter when a change in counting speed occurred
	/// Events should be rescheduled properly inside this member function
	virtual void notify(void) = 0;
	};

	/// Global system counter. It is shared by the architected and memory-mapped
	/// timers.
	class SystemCounter : public SimObject
	{
	protected:
	/// Indicates if the counter is enabled
	bool _enabled;
	/// Counter frequency (as specified by CNTFRQ).
	uint32_t _freq;
	/// Counter value (as specified in CNTCV).
	uint64_t _value;
	/// Value increment in each counter cycle
	uint64_t _increment;
	/// Frequency modes table with all possible frequencies for the counter
	std::vector<uint32_t> _freqTable;
	/// Currently selected entry in the table, its contents should match _freq
	size_t _activeFreqEntry;
	/// Cached copy of the counter period (inverse of the frequency).
	Tick _period;
	/// Counter cycle start Tick when the counter status affecting
	/// its value has been updated
	Tick _updateTick;

	/// Listeners to changes in counting speed
	std::vector<SystemCounterListener *> _listeners;

	/// Maximum architectural number of frequency table entries
	static constexpr size_t MAX_FREQ_ENTRIES = 1004;

	public:
	SystemCounter(const SystemCounterParams &p);

	/// Validates a System Counter reference
	/// @param sys_cnt System counter reference to validate
	static void validateCounterRef(SystemCounter *sys_cnt);

	/// Indicates if the counter is enabled.
	bool enabled() const { return _enabled; }
	/// Returns the counter frequency.
	uint32_t freq() const { return _freq; }
	/// Updates and returns the counter value.
	uint64_t value();
	/// Returns the value increment
	uint64_t increment() const { return _increment; }
	/// Returns a reference to the frequency modes table.
	std::vector<uint32_t>& freqTable() { return _freqTable; }
	/// Returns the currently active frequency table entry.
	size_t activeFreqEntry() const { return _activeFreqEntry; }
	/// Returns the counter period.
	Tick period() const { return _period; }

	/// Enables the counter after a CNTCR.EN == 1
	void enable();
	/// Disables the counter after a CNTCR.EN == 0
	void disable();

	/// Schedules a counter frequency update after a CNTCR.FCREQ == 1
	/// This complies with frequency transitions as per the architecture
	/// @param new_freq_entry Index in CNTFID of the new freq
	void freqUpdateSchedule(size_t new_freq_entry);

	/// Sets the value explicitly from writes to CNTCR.CNTCV
	void setValue(uint64_t new_value);

	/// Called from System Counter Listeners to register
	void registerListener(SystemCounterListener *listener);

	/// Returns the tick at which a certain counter value is reached
	Tick whenValue(uint64_t target_val);
	Tick whenValue(uint64_t cur_val, uint64_t target_val) const;

	void serialize(CheckpointOut &cp) const override;
	void unserialize(CheckpointIn &cp) override;

	private:
	// Disable copying
	SystemCounter(const SystemCounter &c);

	/// Frequency update event handling
	EventFunctionWrapper _freqUpdateEvent;
	size_t _nextFreqEntry;
	/// Callback for the frequency update
	void freqUpdateCallback();

	/// Updates the counter value.
	void updateValue(void);

	/// Updates the update tick, normalizes to the lower cycle start tick
	void updateTick(void);

	/// Notifies counting speed changes to listeners
	void notifyListeners(void) const;
	};

	/// Per-CPU architected timer.
	class ArchTimer : public SystemCounterListener, public Drainable,
	public Serializable
	{
	protected:
	/// Control register.
	BitUnion32(ArchTimerCtrl)
	Bitfield<0> enable;
	Bitfield<1> imask;
	Bitfield<2> istatus;
	EndBitUnion(ArchTimerCtrl)

	/// Name of this timer.
	const std::string _name;

	/// Pointer to parent class.
	SimObject &_parent;

	SystemCounter &_systemCounter;

	ArmInterruptPin * const _interrupt;

	/// Value of the control register ({CNTP/CNTHP/CNTV}_CTL).
	ArchTimerCtrl _control;
	/// Programmed limit value for the upcounter ({CNTP/CNTHP/CNTV}_CVAL).
	uint64_t _counterLimit;
	/// Offset relative to the physical timer (CNTVOFF)
	uint64_t _offset;

	/**
	* Timer settings or the offset has changed, re-evaluate
	* trigger condition and raise interrupt if necessary.
	*/
	void updateCounter();

	/// Called when the upcounter reaches the programmed value.
	void counterLimitReached();
	EventFunctionWrapper _counterLimitReachedEvent;

	virtual bool scheduleEvents() { return true; }

	public:
	ArchTimer(const std::string &name,
	SimObject &parent,
	SystemCounter &sysctr,
	ArmInterruptPin *interrupt);

	/// Returns the timer name.
	std::string name() const { return _name; }

	/// Returns the CompareValue view of the timer.
	uint64_t compareValue() const { return _counterLimit; }
	/// Sets the CompareValue view of the timer.
	void setCompareValue(uint64_t val);

	/// Returns the TimerValue view of the timer.
	uint32_t timerValue() const { return _counterLimit - value(); }
	/// Sets the TimerValue view of the timer.
	void setTimerValue(uint32_t val);

	/// Sets the control register.
	uint32_t control() const { return _control; }
	void setControl(uint32_t val);

	uint64_t offset() const { return _offset; }
	void setOffset(uint64_t val);

	/// Returns the value of the counter which this timer relies on.
	uint64_t value() const;
	Tick whenValue(uint64_t target_val) {
	return _systemCounter.whenValue(value(), target_val);
	}

	void notify(void) override;

	// Serializable
	void serialize(CheckpointOut &cp) const override;
	void unserialize(CheckpointIn &cp) override;

	// Drainable
	DrainState drain() override;
	void drainResume() override;

	private:
	// Disable copying
	ArchTimer(const ArchTimer &t);
	};

	class ArchTimerKvm : public ArchTimer
	{
	private:
	ArmSystem &system;

	public:
	ArchTimerKvm(const std::string &name,
	ArmSystem &system,
	SimObject &parent,
	SystemCounter &sysctr,
	ArmInterruptPin *interrupt)
	: ArchTimer(name, parent, sysctr, interrupt), system(system) {}

	protected:
	// For ArchTimer's in a GenericTimerISA with Kvm execution about
	// to begin, skip rescheduling the event.
	// Otherwise, we should reschedule the event (if necessary).
	bool scheduleEvents() override {
	return !system.validKvmEnvironment();
	}
	};

	class GenericTimer : public SimObject
	{
	public:
	PARAMS(GenericTimer);

	GenericTimer(const Params &p);

	void serialize(CheckpointOut &cp) const override;
	void unserialize(CheckpointIn &cp) override;

	public:
	void setMiscReg(int misc_reg, unsigned cpu, RegVal val);
	RegVal readMiscReg(int misc_reg, unsigned cpu);

	protected:
	class CoreTimers : public SystemCounterListener, public Serializable
	{
	public:
	CoreTimers(GenericTimer &_parent, ArmSystem &system, unsigned cpu,
	ArmInterruptPin _irqPhysS, ArmInterruptPin _irqPhysNS,
	ArmInterruptPin _irqVirt, ArmInterruptPin _irqHyp);

	/// Generic Timer parent reference
	GenericTimer &parent;

	/// System counter frequency as visible from this core
	uint32_t cntfrq;

	/// Kernel control register
	ArmISA::CNTKCTL cntkctl;

	/// Hypervisor control register
	ArmISA::CNTHCTL cnthctl;

	/// Thread (HW) context associated to this PE implementation
	ThreadContext *threadContext;

	ArmInterruptPin const *irqPhysS;
	ArmInterruptPin const *irqPhysNS;
	ArmInterruptPin const *irqVirt;
	ArmInterruptPin const *irqHyp;

	ArchTimerKvm physS;
	ArchTimerKvm physNS;
	ArchTimerKvm virt;
	ArchTimerKvm hyp;

	// Event Stream. Events are generated based on a configurable
	// transitionBit over the counter value. transitionTo indicates
	// the transition direction (0->1 or 1->0)
	struct EventStream
	{
	EventFunctionWrapper event;
	uint8_t transitionTo;
	uint8_t transitionBit;

	uint64_t
	eventTargetValue(uint64_t val) const
	{
	uint64_t bit_val = bits(val, transitionBit);
	uint64_t ret_val = mbits(val, 63, transitionBit);
	uint64_t incr_val = 1 << transitionBit;
	if (bit_val == transitionTo)
	incr_val *= 2;
	return ret_val + incr_val;
	}
	};

	EventStream physEvStream;
	EventStream virtEvStream;
	void physEventStreamCallback();
	void virtEventStreamCallback();
	void eventStreamCallback() const;
	void schedNextEvent(EventStream &ev_stream, ArchTimer &timer);

	void notify(void) override;

	void serialize(CheckpointOut &cp) const override;
	void unserialize(CheckpointIn &cp) override;

	private:
	// Disable copying
	CoreTimers(const CoreTimers &c);
	};

	CoreTimers &getTimers(int cpu_id);
	void createTimers(unsigned cpus);

	/// System counter reference.
	SystemCounter &systemCounter;

	/// Per-CPU physical architected timers.
	std::vector<std::unique_ptr<CoreTimers>> timers;

	protected: // Configuration
	/// ARM system containing this timer
	ArmSystem &system;

	void handleStream(CoreTimers::EventStream *ev_stream,
	ArchTimer *timer, RegVal old_cnt_ctl, RegVal cnt_ctl);
	};

	class GenericTimerISA : public ArmISA::BaseISADevice
	{
	public:
	GenericTimerISA(GenericTimer &_parent, unsigned _cpu)
	: parent(_parent), cpu(_cpu) {}

	void setMiscReg(int misc_reg, RegVal val) override;
	RegVal readMiscReg(int misc_reg) override;

	protected:
	GenericTimer &parent;
	unsigned cpu;
	};

	class GenericTimerFrame : public PioDevice
	{
	public:
	GenericTimerFrame(const GenericTimerFrameParams &p);

	void serialize(CheckpointOut &cp) const override;
	void unserialize(CheckpointIn &cp) override;

	/// Indicates if this frame implements a virtual timer
	bool hasVirtualTimer() const;

	/// Returns the virtual offset for this frame if a virtual timer is
	/// implemented
	uint64_t getVirtOffset() const;

	/// Sets the virtual offset for this frame's virtual timer after
	/// a write to CNTVOFF
	void setVirtOffset(uint64_t new_offset);

	/// Indicates if this frame implements a second EL0 view
	bool hasEl0View() const;

	/// Returns the access bits for this frame
	uint8_t getAccessBits() const;

	/// Updates the access bits after a write to CNTCTLBase.CNTACR
	void setAccessBits(uint8_t data);

	/// Indicates if non-secure accesses are allowed to this frame
	bool hasNonSecureAccess() const;

	/// Allows non-secure accesses after an enabling write to
	/// CNTCTLBase.CNTNSAR
	void setNonSecureAccess();

	/// Indicates if CNTVOFF is readable for this frame
	bool hasReadableVoff() const;

	protected:
	AddrRangeList getAddrRanges() const override;
	Tick read(PacketPtr pkt) override;
	Tick write(PacketPtr pkt) override;

	private:
	/// CNTBase/CNTEL0Base (Memory-mapped timer frame)
	uint64_t timerRead(Addr addr, size_t size, bool is_sec, bool to_el0) const;
	void timerWrite(Addr addr, size_t size, uint64_t data, bool is_sec,
	bool to_el0);
	const AddrRange timerRange;
	AddrRange timerEl0Range;

	static const Addr TIMER_CNTPCT_LO = 0x00;
	static const Addr TIMER_CNTPCT_HI = 0x04;
	static const Addr TIMER_CNTVCT_LO = 0x08;
	static const Addr TIMER_CNTVCT_HI = 0x0c;
	static const Addr TIMER_CNTFRQ = 0x10;
	static const Addr TIMER_CNTEL0ACR = 0x14;
	static const Addr TIMER_CNTVOFF_LO = 0x18;
	static const Addr TIMER_CNTVOFF_HI = 0x1c;
	static const Addr TIMER_CNTP_CVAL_LO = 0x20;
	static const Addr TIMER_CNTP_CVAL_HI = 0x24;
	static const Addr TIMER_CNTP_TVAL = 0x28;
	static const Addr TIMER_CNTP_CTL = 0x2c;
	static const Addr TIMER_CNTV_CVAL_LO = 0x30;
	static const Addr TIMER_CNTV_CVAL_HI = 0x34;
	static const Addr TIMER_CNTV_TVAL = 0x38;
	static const Addr TIMER_CNTV_CTL = 0x3c;

	/// All MMIO ranges GenericTimerFrame responds to
	AddrRangeList addrRanges;

	/// System counter reference.
	SystemCounter &systemCounter;

	/// Physical and virtual timers
	ArchTimer physTimer;
	ArchTimer virtTimer;

	/// Reports access properties of the CNTBase register frame elements
	BitUnion8(AccessBits)
	Bitfield<5> rwpt;
	Bitfield<4> rwvt;
	Bitfield<3> rvoff;
	Bitfield<2> rfrq;
	Bitfield<1> rvct;
	Bitfield<0> rpct;
	EndBitUnion(AccessBits)
	AccessBits accessBits;

	// Reports access properties of the CNTEL0Base register frame elements
	BitUnion16(AccessBitsEl0)
	Bitfield<9> pten;
	Bitfield<8> vten;
	Bitfield<1> vcten;
	Bitfield<0> pcten;
	EndBitUnion(AccessBitsEl0)
	AccessBitsEl0 accessBitsEl0;

	/// Reports whether non-secure accesses are allowed to this frame
	bool nonSecureAccess;

	ArmSystem &system;
	};

	class GenericTimerMem : public PioDevice
	{
	public:
	GenericTimerMem(const GenericTimerMemParams &p);

	/// Validates a Generic Timer register frame address range
	/// @param base_addr Range of the register frame
	static void validateFrameRange(const AddrRange &range);

	/// Validates an MMIO access permissions
	/// @param sys System reference where the acces is being made
	/// @param is_sec If the access is to secure memory
	static bool validateAccessPerm(ArmSystem &sys, bool is_sec);

	protected:
	AddrRangeList getAddrRanges() const override;
	Tick read(PacketPtr pkt) override;
	Tick write(PacketPtr pkt) override;

	private:
	/// CNTControlBase (System counter control frame)
	uint64_t counterCtrlRead(Addr addr, size_t size, bool is_sec) const;
	void counterCtrlWrite(Addr addr, size_t size, uint64_t data, bool is_sec);
	const AddrRange counterCtrlRange;

	BitUnion32(CNTCR)
	Bitfield<17,8> fcreq;
	Bitfield<2> scen;
	Bitfield<1> hdbg;
	Bitfield<0> en;
	EndBitUnion(CNTCR)

	BitUnion32(CNTSR)
	Bitfield<31,8> fcack;
	EndBitUnion(CNTSR)

	static const Addr COUNTER_CTRL_CNTCR = 0x00;
	static const Addr COUNTER_CTRL_CNTSR = 0x04;
	static const Addr COUNTER_CTRL_CNTCV_LO = 0x08;
	static const Addr COUNTER_CTRL_CNTCV_HI = 0x0c;
	static const Addr COUNTER_CTRL_CNTSCR = 0x10;
	static const Addr COUNTER_CTRL_CNTID = 0x1c;
	static const Addr COUNTER_CTRL_CNTFID = 0x20;

	/// CNTReadBase (System counter status frame)
	uint64_t counterStatusRead(Addr addr, size_t size) const;
	void counterStatusWrite(Addr addr, size_t size, uint64_t data);
	const AddrRange counterStatusRange;

	static const Addr COUNTER_STATUS_CNTCV_LO = 0x00;
	static const Addr COUNTER_STATUS_CNTCV_HI = 0x04;

	/// CNTCTLBase (Memory-mapped timer global control frame)
	uint64_t timerCtrlRead(Addr addr, size_t size, bool is_sec) const;
	void timerCtrlWrite(Addr addr, size_t size, uint64_t data, bool is_sec);
	const AddrRange timerCtrlRange;

	/// ID register for reporting features of implemented timer frames
	uint32_t cnttidr;

	static const Addr TIMER_CTRL_CNTFRQ = 0x00;
	static const Addr TIMER_CTRL_CNTNSAR = 0x04;
	static const Addr TIMER_CTRL_CNTTIDR = 0x08;
	static const Addr TIMER_CTRL_CNTACR = 0x40;
	static const Addr TIMER_CTRL_CNTVOFF_LO = 0x80;
	static const Addr TIMER_CTRL_CNTVOFF_HI = 0x84;

	/// All MMIO ranges GenericTimerMem responds to
	const AddrRangeList addrRanges;

	/// System counter reference.
	SystemCounter &systemCounter;

	/// Maximum architectural number of memory-mapped timer frames
	static constexpr size_t MAX_TIMER_FRAMES = 8;

	/// Timer frame references
	std::vector<GenericTimerFrame *> frames;

	ArmSystem &system;
	};

	#endif // __DEV_ARM_GENERIC_TIMER_HH__