#include "qemu/osdep.h"
#include "hw/irq.h"
#include "hw/qdev-properties.h"
#include "net/net.h"
#include "qemu/module.h"
#include "trace.h"
#include "hw/sysbus.h"
#include "migration/vmstate.h"

/* MIPSnet register offsets */

#define MIPSNET_DEV_ID          0x00
#define MIPSNET_BUSY            0x08
#define MIPSNET_RX_DATA_COUNT   0x0c
#define MIPSNET_TX_DATA_COUNT   0x10
#define MIPSNET_INT_CTL         0x14
# define MIPSNET_INTCTL_TXDONE          0x00000001
# define MIPSNET_INTCTL_RXDONE          0x00000002
# define MIPSNET_INTCTL_TESTBIT         0x80000000
#define MIPSNET_INTERRUPT_INFO  0x18
#define MIPSNET_RX_DATA_BUFFER  0x1c
#define MIPSNET_TX_DATA_BUFFER  0x20

#define MAX_ETH_FRAME_SIZE      1514

#define TYPE_MIPS_NET "mipsnet"
#define MIPS_NET(obj) OBJECT_CHECK(MIPSnetState, (obj), TYPE_MIPS_NET)

typedef struct MIPSnetState {
    SysBusDevice parent_obj;

    uint32_t busy;
    uint32_t rx_count;
    uint32_t rx_read;
    uint32_t tx_count;
    uint32_t tx_written;
    uint32_t intctl;
    uint8_t rx_buffer[MAX_ETH_FRAME_SIZE];
    uint8_t tx_buffer[MAX_ETH_FRAME_SIZE];
    MemoryRegion io;
    qemu_irq irq;
    NICState *nic;
    NICConf conf;
} MIPSnetState;

static void mipsnet_reset(MIPSnetState *s)
{
    s->busy = 1;
    s->rx_count = 0;
    s->rx_read = 0;
    s->tx_count = 0;
    s->tx_written = 0;
    s->intctl = 0;
    memset(s->rx_buffer, 0, MAX_ETH_FRAME_SIZE);
    memset(s->tx_buffer, 0, MAX_ETH_FRAME_SIZE);
}

static void mipsnet_update_irq(MIPSnetState *s)
{
    int isr = !!s->intctl;
    trace_mipsnet_irq(isr, s->intctl);
    qemu_set_irq(s->irq, isr);
}

static int mipsnet_buffer_full(MIPSnetState *s)
{
    if (s->rx_count >= MAX_ETH_FRAME_SIZE) {
        return 1;
    }
    return 0;
}

static int mipsnet_can_receive(NetClientState *nc)
{
    MIPSnetState *s = qemu_get_nic_opaque(nc);

    if (s->busy) {
        return 0;
    }
    return !mipsnet_buffer_full(s);
}

static ssize_t mipsnet_receive(NetClientState *nc,
                               const uint8_t *buf, size_t size)
{
    MIPSnetState *s = qemu_get_nic_opaque(nc);

    trace_mipsnet_receive(size);
    if (!mipsnet_can_receive(nc)) {
        return 0;
    }

    if (size >= sizeof(s->rx_buffer)) {
        return 0;
    }
    s->busy = 1;

    /* Just accept everything. */

    /* Write packet data. */
    memcpy(s->rx_buffer, buf, size);

    s->rx_count = size;
    s->rx_read = 0;

    /* Now we can signal we have received something. */
    s->intctl |= MIPSNET_INTCTL_RXDONE;
    mipsnet_update_irq(s);

    return size;
}

static uint64_t mipsnet_ioport_read(void *opaque, hwaddr addr,
                                    unsigned int size)
{
    MIPSnetState *s = opaque;
    int ret = 0;

    addr &= 0x3f;
    switch (addr) {
    case MIPSNET_DEV_ID:
        ret = be32_to_cpu(0x4d495053);          /* MIPS */
        break;
    case MIPSNET_DEV_ID + 4:
        ret = be32_to_cpu(0x4e455430);          /* NET0 */
        break;
    case MIPSNET_BUSY:
        ret = s->busy;
        break;
    case MIPSNET_RX_DATA_COUNT:
        ret = s->rx_count;
        break;
    case MIPSNET_TX_DATA_COUNT:
        ret = s->tx_count;
        break;
    case MIPSNET_INT_CTL:
        ret = s->intctl;
        s->intctl &= ~MIPSNET_INTCTL_TESTBIT;
        break;
    case MIPSNET_INTERRUPT_INFO:
        /* XXX: This seems to be a per-VPE interrupt number. */
        ret = 0;
        break;
    case MIPSNET_RX_DATA_BUFFER:
        if (s->rx_count) {
            s->rx_count--;
            ret = s->rx_buffer[s->rx_read++];
            if (mipsnet_can_receive(s->nic->ncs)) {
                qemu_flush_queued_packets(qemu_get_queue(s->nic));
            }
        }
        break;
    /* Reads as zero. */
    case MIPSNET_TX_DATA_BUFFER:
    default:
        break;
    }
    trace_mipsnet_read(addr, ret);
    return ret;
}

static void mipsnet_ioport_write(void *opaque, hwaddr addr,
                                 uint64_t val, unsigned int size)
{
    MIPSnetState *s = opaque;

    addr &= 0x3f;
    trace_mipsnet_write(addr, val);
    switch (addr) {
    case MIPSNET_TX_DATA_COUNT:
        s->tx_count = (val <= MAX_ETH_FRAME_SIZE) ? val : 0;
        s->tx_written = 0;
        break;
    case MIPSNET_INT_CTL:
        if (val & MIPSNET_INTCTL_TXDONE) {
            s->intctl &= ~MIPSNET_INTCTL_TXDONE;
        } else if (val & MIPSNET_INTCTL_RXDONE) {
            s->intctl &= ~MIPSNET_INTCTL_RXDONE;
        } else if (val & MIPSNET_INTCTL_TESTBIT) {
            mipsnet_reset(s);
            s->intctl |= MIPSNET_INTCTL_TESTBIT;
        } else if (!val) {
            /* ACK testbit interrupt, flag was cleared on read. */
        }
        s->busy = !!s->intctl;
        mipsnet_update_irq(s);
        if (mipsnet_can_receive(s->nic->ncs)) {
            qemu_flush_queued_packets(qemu_get_queue(s->nic));
        }
        break;
    case MIPSNET_TX_DATA_BUFFER:
        s->tx_buffer[s->tx_written++] = val;
        if ((s->tx_written >= MAX_ETH_FRAME_SIZE)
            || (s->tx_written == s->tx_count)) {
            /* Send buffer. */
            trace_mipsnet_send(s->tx_written);
            qemu_send_packet(qemu_get_queue(s->nic),
                                s->tx_buffer, s->tx_written);
            s->tx_count = s->tx_written = 0;
            s->intctl |= MIPSNET_INTCTL_TXDONE;
            s->busy = 1;
            mipsnet_update_irq(s);
        }
        break;
    /* Read-only registers */
    case MIPSNET_DEV_ID:
    case MIPSNET_BUSY:
    case MIPSNET_RX_DATA_COUNT:
    case MIPSNET_INTERRUPT_INFO:
    case MIPSNET_RX_DATA_BUFFER:
    default:
        break;
    }
}

static const VMStateDescription vmstate_mipsnet = {
    .name = "mipsnet",
    .version_id = 0,
    .minimum_version_id = 0,
    .fields = (VMStateField[]) {
        VMSTATE_UINT32(busy, MIPSnetState),
        VMSTATE_UINT32(rx_count, MIPSnetState),
        VMSTATE_UINT32(rx_read, MIPSnetState),
        VMSTATE_UINT32(tx_count, MIPSnetState),
        VMSTATE_UINT32(tx_written, MIPSnetState),
        VMSTATE_UINT32(intctl, MIPSnetState),
        VMSTATE_BUFFER(rx_buffer, MIPSnetState),
        VMSTATE_BUFFER(tx_buffer, MIPSnetState),
        VMSTATE_END_OF_LIST()
    }
};

static NetClientInfo net_mipsnet_info = {
    .type = NET_CLIENT_DRIVER_NIC,
    .size = sizeof(NICState),
    .receive = mipsnet_receive,
};

static const MemoryRegionOps mipsnet_ioport_ops = {
    .read = mipsnet_ioport_read,
    .write = mipsnet_ioport_write,
    .impl.min_access_size = 1,
    .impl.max_access_size = 4,
};

static void mipsnet_realize(DeviceState *dev, Error **errp)
{
    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
    MIPSnetState *s = MIPS_NET(dev);

    memory_region_init_io(&s->io, OBJECT(dev), &mipsnet_ioport_ops, s,
                          "mipsnet-io", 36);
    sysbus_init_mmio(sbd, &s->io);
    sysbus_init_irq(sbd, &s->irq);

    s->nic = qemu_new_nic(&net_mipsnet_info, &s->conf,
                          object_get_typename(OBJECT(dev)), dev->id, s);
    qemu_format_nic_info_str(qemu_get_queue(s->nic), s->conf.macaddr.a);
}

static void mipsnet_sysbus_reset(DeviceState *dev)
{
    MIPSnetState *s = MIPS_NET(dev);
    mipsnet_reset(s);
}

static Property mipsnet_properties[] = {
    DEFINE_NIC_PROPERTIES(MIPSnetState, conf),
    DEFINE_PROP_END_OF_LIST(),
};

static void mipsnet_class_init(ObjectClass *klass, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);

    dc->realize = mipsnet_realize;
    set_bit(DEVICE_CATEGORY_NETWORK, dc->categories);
    dc->desc = "MIPS Simulator network device";
    dc->reset = mipsnet_sysbus_reset;
    dc->vmsd = &vmstate_mipsnet;
    device_class_set_props(dc, mipsnet_properties);
}

static const TypeInfo mipsnet_info = {
    .name          = TYPE_MIPS_NET,
    .parent        = TYPE_SYS_BUS_DEVICE,
    .instance_size = sizeof(MIPSnetState),
    .class_init    = mipsnet_class_init,
};

static void mipsnet_register_types(void)
{
    type_register_static(&mipsnet_info);
}

type_init(mipsnet_register_types)