qemu-initiator-signal-socket.h

/*
 * This file is part of libqbox
 * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All Rights Reserved.
 * Author: GreenSocs 2021
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
 
#ifndef _LIBQBOX_PORTS_INITIATOR_SIGNAL_SOCKET_H
#define _LIBQBOX_PORTS_INITIATOR_SIGNAL_SOCKET_H
 
#include <functional>
#include <cassert>
 
#include <libqemu-cxx/libqemu-cxx.h>
 
#include <ports/target-signal-socket.h>
#include <ports/initiator-signal-socket.h>
 
#include <libgssync.h>
 
#include <ports/qemu-target-signal-socket.h>
 
class QemuInitiatorSignalSocket : public InitiatorSignalSocket<bool>
{
protected:
    qemu::Gpio m_proxy;
    gs::runonsysc m_on_sysc;
    QemuTargetSignalSocket* m_qemu_remote = nullptr;
 
    void event_cb(bool val)
    {
        if (m_qemu_remote && (m_qemu_remote->get_gpio().same_inst_as(m_proxy))) {
            /*
             * We make sure to be in the same instance as the target socket.
             * Otherwise we would need to hold the target's QEMU instance
             * iothread lock. This would require us to unlock our own lock
             * first to ensure we won't deadlock because of a race condition
             * between two initiators trying to set a GPIO in one another.
             * Don't bother with that. Instead, use the SystemC kernel as a
             * synchronization point in this case.
             */
            m_qemu_remote->get_gpio().set(val);
 
            m_on_sysc.run_on_sysc([this] { m_qemu_remote->notify(); }, false);
 
            return;
        }
 
        if (!get_interface()) {
            return;
        }
 
        m_proxy.get_inst().unlock_iothread();
 
        m_on_sysc.run_on_sysc([this, val] { (*this)->write(val); });
 
        m_proxy.get_inst().lock_iothread();
    }
 
    void init_qemu_to_sysc_gpio_proxy(qemu::Device& dev)
    {
        using namespace std::placeholders;
 
        m_proxy = dev.get_inst().gpio_new();
 
        auto cb = std::bind(&QemuInitiatorSignalSocket::event_cb, this, _1);
        m_proxy.set_event_callback(cb);
    }
 
    void init_internal(qemu::Device& dev)
    {
        sc_core::sc_interface* iface;
        TargetSignalSocketProxy<bool>* socket_iface;
        QemuTargetSignalSocket* remote;
 
        init_qemu_to_sysc_gpio_proxy(dev);
 
        iface = get_interface();
 
        /* Check if we're bound to a TargetSignalSocket<bool> */
        socket_iface = dynamic_cast<TargetSignalSocketProxy<bool>*>(iface);
 
        if (socket_iface == nullptr) {
            return;
        }
 
        /* Check if we're bound to a QemuTargetSignalSocket */
        remote = dynamic_cast<QemuTargetSignalSocket*>(&socket_iface->get_parent());
 
        if (remote == nullptr) {
            return;
        }
 
        /*
         * We could connect the GPIOs from within QEMU directly, but we don't
         * know if the remote initialization is done yet. Instead, keep a
         * pointer on the remote to change its GPIO directly in event_cb()
         * instead of going through the SystemC kernel.
         */
        m_qemu_remote = remote;
    }
 
public:
    QemuInitiatorSignalSocket(const char* name)
        : InitiatorSignalSocket<bool>(name), m_on_sysc(sc_core::sc_gen_unique_name("run_on_sysc"))
    {
    }
 
    ~QemuInitiatorSignalSocket() { m_proxy.set_event_callback(nullptr); }
 
    void init(qemu::Device dev, int gpio_idx)
    {
        init_internal(dev);
        dev.connect_gpio_out(gpio_idx, m_proxy);
    }
 
    void init_named(qemu::Device dev, const char* gpio_name, int gpio_idx)
    {
        init_internal(dev);
        dev.connect_gpio_out_named(gpio_name, gpio_idx, m_proxy);
    }
 
    void init_sbd(qemu::SysBusDevice sbd, int gpio_idx)
    {
        init_internal(sbd);
        sbd.connect_gpio_out(gpio_idx, m_proxy);
    }
};
 
#endif