src/dev/lupio/lupio_tmr.hh

/*
 * Copyright (c) 2021 The Regents of the University of California
 * All rights reserved.
 *
 * 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,
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#ifndef __DEV_LUPIO_LUPIO_TMR_HH__
#define __DEV_LUPIO_LUPIO_TMR_HH__

#include "arch/riscv/interrupts.hh"
#include "dev/io_device.hh"
#include "dev/platform.hh"
#include "params/LupioTMR.hh"

namespace gem5
{

/**
 * LupioTMR:
 * A virtual timer device which provides a real time counter, as well as a
 * configurable timer offering periodic and one shot modes.
 */

class LupioTMR : public BasicPioDevice
{
  private:
    const ByteOrder byteOrder = ByteOrder::little;
    System *system;
    int nThread;
    int intType;

    // Register map
    enum
    {
        LUPIO_TMR_TIME = 0x0,
        LUPIO_TMR_LOAD = 0x4,
        LUPIO_TMR_CTRL = 0x8,
        LUPIO_TMR_STAT = 0xC,

        // Max offset
        LUPIO_TMR_MAX = 0x10,
    };

    struct LupioTimer
    {
        Event *tmrEvent = nullptr;
        uint64_t reload = 0;
        bool ie = false;            // Control
        bool pd = false;
        bool expired = false;       // Status
        Tick startTime = 0;
    };

    std::vector<LupioTimer> timers;

    /**
     * Function to return data pertaining to the timer, such as the simulated
     * time in ticks
     */
    uint64_t lupioTMRRead(const uint8_t addr, int size);
    /**
     * Function to launch or stop the timer depending on the load value
     */
    void lupioTMRWrite(const uint8_t addr, uint64_t val64, int size);

    /**
     * Return the simulated time
     */
    uint64_t lupioTMRCurrentTime();
    /**
     * Schedule the next timer event
     */
    void lupioTMRSet(int cpu);
    /**
     * Process the timer's event
     */
    void lupioTMRCallback(int cpu);

    /**
     * Post or clear timer interrupts
     */
    void updateIRQ(int level, int cpu);

  public:
    PARAMS(LupioTMR);
    LupioTMR(const Params &params);
    ~LupioTMR();

    /**
     * Implement BasicPioDevice virtual functions
     */
    Tick read(PacketPtr pkt) override;
    Tick write(PacketPtr pkt) override;
};

} // namespace gem5

#endif // __DEV_LUPIO_LUPIO_TMR_HH_