/*
 * Luminary Micro Stellaris Ethernet Controller
 *
 * Copyright (c) 2007 CodeSourcery.
 * Written by Paul Brook
 *
 * This code is licensed under the GPL.
 */

#include "qemu/osdep.h"
#include "hw/irq.h"
#include "hw/sysbus.h"
#include "net/net.h"
#include "qemu/log.h"
#include "qemu/module.h"
#include <zlib.h>

//#define DEBUG_STELLARIS_ENET 1

#ifdef DEBUG_STELLARIS_ENET
#define DPRINTF(fmt, ...) \
do { printf("stellaris_enet: " fmt , ## __VA_ARGS__); } while (0)
#define BADF(fmt, ...) \
do { fprintf(stderr, "stellaris_enet: error: " fmt , ## __VA_ARGS__); exit(1);} while (0)
#else
#define DPRINTF(fmt, ...) do {} while(0)
#define BADF(fmt, ...) \
do { fprintf(stderr, "stellaris_enet: error: " fmt , ## __VA_ARGS__);} while (0)
#endif

#define SE_INT_RX       0x01
#define SE_INT_TXER     0x02
#define SE_INT_TXEMP    0x04
#define SE_INT_FOV      0x08
#define SE_INT_RXER     0x10
#define SE_INT_MD       0x20
#define SE_INT_PHY      0x40

#define SE_RCTL_RXEN    0x01
#define SE_RCTL_AMUL    0x02
#define SE_RCTL_PRMS    0x04
#define SE_RCTL_BADCRC  0x08
#define SE_RCTL_RSTFIFO 0x10

#define SE_TCTL_TXEN    0x01
#define SE_TCTL_PADEN   0x02
#define SE_TCTL_CRC     0x04
#define SE_TCTL_DUPLEX  0x08

#define TYPE_STELLARIS_ENET "stellaris_enet"
#define STELLARIS_ENET(obj) \
    OBJECT_CHECK(stellaris_enet_state, (obj), TYPE_STELLARIS_ENET)

typedef struct {
    uint8_t data[2048];
    uint32_t len;
} StellarisEnetRxFrame;

typedef struct {
    SysBusDevice parent_obj;

    uint32_t ris;
    uint32_t im;
    uint32_t rctl;
    uint32_t tctl;
    uint32_t thr;
    uint32_t mctl;
    uint32_t mdv;
    uint32_t mtxd;
    uint32_t mrxd;
    uint32_t np;
    uint32_t tx_fifo_len;
    uint8_t tx_fifo[2048];
    /* Real hardware has a 2k fifo, which works out to be at most 31 packets.
       We implement a full 31 packet fifo.  */
    StellarisEnetRxFrame rx[31];
    uint32_t rx_fifo_offset;
    uint32_t next_packet;
    NICState *nic;
    NICConf conf;
    qemu_irq irq;
    MemoryRegion mmio;
} stellaris_enet_state;

static const VMStateDescription vmstate_rx_frame = {
    .name = "stellaris_enet/rx_frame",
    .version_id = 1,
    .minimum_version_id = 1,
    .fields = (VMStateField[]) {
        VMSTATE_UINT8_ARRAY(data, StellarisEnetRxFrame, 2048),
        VMSTATE_UINT32(len, StellarisEnetRxFrame),
        VMSTATE_END_OF_LIST()
    }
};

static int stellaris_enet_post_load(void *opaque, int version_id)
{
    stellaris_enet_state *s = opaque;
    int i;

    /* Sanitize inbound state. Note that next_packet is an index but
     * np is a size; hence their valid upper bounds differ.
     */
    if (s->next_packet >= ARRAY_SIZE(s->rx)) {
        return -1;
    }

    if (s->np > ARRAY_SIZE(s->rx)) {
        return -1;
    }

    for (i = 0; i < ARRAY_SIZE(s->rx); i++) {
        if (s->rx[i].len > ARRAY_SIZE(s->rx[i].data)) {
            return -1;
        }
    }

    if (s->rx_fifo_offset > ARRAY_SIZE(s->rx[0].data) - 4) {
        return -1;
    }

    if (s->tx_fifo_len > ARRAY_SIZE(s->tx_fifo)) {
        return -1;
    }

    return 0;
}

static const VMStateDescription vmstate_stellaris_enet = {
    .name = "stellaris_enet",
    .version_id = 2,
    .minimum_version_id = 2,
    .post_load = stellaris_enet_post_load,
    .fields = (VMStateField[]) {
        VMSTATE_UINT32(ris, stellaris_enet_state),
        VMSTATE_UINT32(im, stellaris_enet_state),
        VMSTATE_UINT32(rctl, stellaris_enet_state),
        VMSTATE_UINT32(tctl, stellaris_enet_state),
        VMSTATE_UINT32(thr, stellaris_enet_state),
        VMSTATE_UINT32(mctl, stellaris_enet_state),
        VMSTATE_UINT32(mdv, stellaris_enet_state),
        VMSTATE_UINT32(mtxd, stellaris_enet_state),
        VMSTATE_UINT32(mrxd, stellaris_enet_state),
        VMSTATE_UINT32(np, stellaris_enet_state),
        VMSTATE_UINT32(tx_fifo_len, stellaris_enet_state),
        VMSTATE_UINT8_ARRAY(tx_fifo, stellaris_enet_state, 2048),
        VMSTATE_STRUCT_ARRAY(rx, stellaris_enet_state, 31, 1,
                             vmstate_rx_frame, StellarisEnetRxFrame),
        VMSTATE_UINT32(rx_fifo_offset, stellaris_enet_state),
        VMSTATE_UINT32(next_packet, stellaris_enet_state),
        VMSTATE_END_OF_LIST()
    }
};

static void stellaris_enet_update(stellaris_enet_state *s)
{
    qemu_set_irq(s->irq, (s->ris & s->im) != 0);
}

/* Return the data length of the packet currently being assembled
 * in the TX fifo.
 */
static inline int stellaris_txpacket_datalen(stellaris_enet_state *s)
{
    return s->tx_fifo[0] | (s->tx_fifo[1] << 8);
}

/* Return true if the packet currently in the TX FIFO is complete,
* ie the FIFO holds enough bytes for the data length, ethernet header,
* payload and optionally CRC.
*/
static inline bool stellaris_txpacket_complete(stellaris_enet_state *s)
{
    int framelen = stellaris_txpacket_datalen(s);
    framelen += 16;
    if (!(s->tctl & SE_TCTL_CRC)) {
        framelen += 4;
    }
    /* Cover the corner case of a 2032 byte payload with auto-CRC disabled:
     * this requires more bytes than will fit in the FIFO. It's not totally
     * clear how the h/w handles this, but if using threshold-based TX
     * it will definitely try to transmit something.
     */
    framelen = MIN(framelen, ARRAY_SIZE(s->tx_fifo));
    return s->tx_fifo_len >= framelen;
}

/* Return true if the TX FIFO threshold is enabled and the FIFO
 * has filled enough to reach it.
 */
static inline bool stellaris_tx_thr_reached(stellaris_enet_state *s)
{
    return (s->thr < 0x3f &&
            (s->tx_fifo_len >= 4 * (s->thr * 8 + 1)));
}

/* Send the packet currently in the TX FIFO */
static void stellaris_enet_send(stellaris_enet_state *s)
{
    int framelen = stellaris_txpacket_datalen(s);

    /* Ethernet header is in the FIFO but not in the datacount.
     * We don't implement explicit CRC, so just ignore any
     * CRC value in the FIFO.
     */
    framelen += 14;
    if ((s->tctl & SE_TCTL_PADEN) && framelen < 60) {
        memset(&s->tx_fifo[framelen + 2], 0, 60 - framelen);
        framelen = 60;
    }
    /* This MIN will have no effect unless the FIFO data is corrupt
     * (eg bad data from an incoming migration); otherwise the check
     * on the datalen at the start of writing the data into the FIFO
     * will have caught this. Silently write a corrupt half-packet,
     * which is what the hardware does in FIFO underrun situations.
     */
    framelen = MIN(framelen, ARRAY_SIZE(s->tx_fifo) - 2);
    qemu_send_packet(qemu_get_queue(s->nic), s->tx_fifo + 2, framelen);
    s->tx_fifo_len = 0;
    s->ris |= SE_INT_TXEMP;
    stellaris_enet_update(s);
    DPRINTF("Done TX\n");
}

/* TODO: Implement MAC address filtering.  */
static ssize_t stellaris_enet_receive(NetClientState *nc, const uint8_t *buf, size_t size)
{
    stellaris_enet_state *s = qemu_get_nic_opaque(nc);
    int n;
    uint8_t *p;
    uint32_t crc;

    if ((s->rctl & SE_RCTL_RXEN) == 0)
        return -1;
    if (s->np >= 31) {
        return 0;
    }

    DPRINTF("Received packet len=%zu\n", size);
    n = s->next_packet + s->np;
    if (n >= 31)
        n -= 31;

    if (size >= sizeof(s->rx[n].data) - 6) {
        /* If the packet won't fit into the
         * emulated 2K RAM, this is reported
         * as a FIFO overrun error.
         */
        s->ris |= SE_INT_FOV;
        stellaris_enet_update(s);
        return -1;
    }

    s->np++;
    s->rx[n].len = size + 6;
    p = s->rx[n].data;
    *(p++) = (size + 6);
    *(p++) = (size + 6) >> 8;
    memcpy (p, buf, size);
    p += size;
    crc = crc32(~0, buf, size);
    *(p++) = crc;
    *(p++) = crc >> 8;
    *(p++) = crc >> 16;
    *(p++) = crc >> 24;
    /* Clear the remaining bytes in the last word.  */
    if ((size & 3) != 2) {
        memset(p, 0, (6 - size) & 3);
    }

    s->ris |= SE_INT_RX;
    stellaris_enet_update(s);

    return size;
}

static int stellaris_enet_can_receive(stellaris_enet_state *s)
{
    return (s->np < 31);
}

static uint64_t stellaris_enet_read(void *opaque, hwaddr offset,
                                    unsigned size)
{
    stellaris_enet_state *s = (stellaris_enet_state *)opaque;
    uint32_t val;

    switch (offset) {
    case 0x00: /* RIS */
        DPRINTF("IRQ status %02x\n", s->ris);
        return s->ris;
    case 0x04: /* IM */
        return s->im;
    case 0x08: /* RCTL */
        return s->rctl;
    case 0x0c: /* TCTL */
        return s->tctl;
    case 0x10: /* DATA */
    {
        uint8_t *rx_fifo;

        if (s->np == 0) {
            BADF("RX underflow\n");
            return 0;
        }

        rx_fifo = s->rx[s->next_packet].data + s->rx_fifo_offset;

        val = rx_fifo[0] | (rx_fifo[1] << 8) | (rx_fifo[2] << 16)
              | (rx_fifo[3] << 24);
        s->rx_fifo_offset += 4;
        if (s->rx_fifo_offset >= s->rx[s->next_packet].len) {
            s->rx_fifo_offset = 0;
            s->next_packet++;
            if (s->next_packet >= 31)
                s->next_packet = 0;
            s->np--;
            DPRINTF("RX done np=%d\n", s->np);
            if (!s->np && stellaris_enet_can_receive(s)) {
                qemu_flush_queued_packets(qemu_get_queue(s->nic));
            }
        }
        return val;
    }
    case 0x14: /* IA0 */
        return s->conf.macaddr.a[0] | (s->conf.macaddr.a[1] << 8)
            | (s->conf.macaddr.a[2] << 16)
            | ((uint32_t)s->conf.macaddr.a[3] << 24);
    case 0x18: /* IA1 */
        return s->conf.macaddr.a[4] | (s->conf.macaddr.a[5] << 8);
    case 0x1c: /* THR */
        return s->thr;
    case 0x20: /* MCTL */
        return s->mctl;
    case 0x24: /* MDV */
        return s->mdv;
    case 0x28: /* MADD */
        return 0;
    case 0x2c: /* MTXD */
        return s->mtxd;
    case 0x30: /* MRXD */
        return s->mrxd;
    case 0x34: /* NP */
        return s->np;
    case 0x38: /* TR */
        return 0;
    case 0x3c: /* Undocumented: Timestamp? */
        return 0;
    default:
        qemu_log_mask(LOG_GUEST_ERROR, "stellaris_enet_rd%d: Illegal register"
                                       " 0x02%" HWADDR_PRIx "\n",
                      size * 8, offset);
        return 0;
    }
}

static void stellaris_enet_write(void *opaque, hwaddr offset,
                                 uint64_t value, unsigned size)
{
    stellaris_enet_state *s = (stellaris_enet_state *)opaque;

    switch (offset) {
    case 0x00: /* IACK */
        s->ris &= ~value;
        DPRINTF("IRQ ack %02" PRIx64 "/%02x\n", value, s->ris);
        stellaris_enet_update(s);
        /* Clearing TXER also resets the TX fifo.  */
        if (value & SE_INT_TXER) {
            s->tx_fifo_len = 0;
        }
        break;
    case 0x04: /* IM */
        DPRINTF("IRQ mask %02" PRIx64 "/%02x\n", value, s->ris);
        s->im = value;
        stellaris_enet_update(s);
        break;
    case 0x08: /* RCTL */
        s->rctl = value;
        if (value & SE_RCTL_RSTFIFO) {
            s->np = 0;
            s->rx_fifo_offset = 0;
            stellaris_enet_update(s);
        }
        break;
    case 0x0c: /* TCTL */
        s->tctl = value;
        break;
    case 0x10: /* DATA */
        if (s->tx_fifo_len == 0) {
            /* The first word is special, it contains the data length */
            int framelen = value & 0xffff;
            if (framelen > 2032) {
                DPRINTF("TX frame too long (%d)\n", framelen);
                s->ris |= SE_INT_TXER;
                stellaris_enet_update(s);
                break;
            }
        }

        if (s->tx_fifo_len + 4 <= ARRAY_SIZE(s->tx_fifo)) {
            s->tx_fifo[s->tx_fifo_len++] = value;
            s->tx_fifo[s->tx_fifo_len++] = value >> 8;
            s->tx_fifo[s->tx_fifo_len++] = value >> 16;
            s->tx_fifo[s->tx_fifo_len++] = value >> 24;
        }

        if (stellaris_tx_thr_reached(s) && stellaris_txpacket_complete(s)) {
            stellaris_enet_send(s);
        }
        break;
    case 0x14: /* IA0 */
        s->conf.macaddr.a[0] = value;
        s->conf.macaddr.a[1] = value >> 8;
        s->conf.macaddr.a[2] = value >> 16;
        s->conf.macaddr.a[3] = value >> 24;
        break;
    case 0x18: /* IA1 */
        s->conf.macaddr.a[4] = value;
        s->conf.macaddr.a[5] = value >> 8;
        break;
    case 0x1c: /* THR */
        s->thr = value;
        break;
    case 0x20: /* MCTL */
        /* TODO: MII registers aren't modelled.
         * Clear START, indicating that the operation completes immediately.
         */
        s->mctl = value & ~1;
        break;
    case 0x24: /* MDV */
        s->mdv = value;
        break;
    case 0x28: /* MADD */
        /* ignored.  */
        break;
    case 0x2c: /* MTXD */
        s->mtxd = value & 0xff;
        break;
    case 0x38: /* TR */
        if (value & 1) {
            stellaris_enet_send(s);
        }
        break;
    case 0x30: /* MRXD */
    case 0x34: /* NP */
        /* Ignored.  */
    case 0x3c: /* Undocuented: Timestamp? */
        /* Ignored.  */
        break;
    default:
        qemu_log_mask(LOG_GUEST_ERROR, "stellaris_enet_wr%d: Illegal register "
                                       "0x02%" HWADDR_PRIx " = 0x%" PRIx64 "\n",
                      size * 8, offset, value);
    }
}

static const MemoryRegionOps stellaris_enet_ops = {
    .read = stellaris_enet_read,
    .write = stellaris_enet_write,
    .endianness = DEVICE_NATIVE_ENDIAN,
};

static void stellaris_enet_reset(DeviceState *dev)
{
    stellaris_enet_state *s =  STELLARIS_ENET(dev);

    s->mdv = 0x80;
    s->rctl = SE_RCTL_BADCRC;
    s->im = SE_INT_PHY | SE_INT_MD | SE_INT_RXER | SE_INT_FOV | SE_INT_TXEMP
            | SE_INT_TXER | SE_INT_RX;
    s->thr = 0x3f;
    s->tx_fifo_len = 0;
}

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

static void stellaris_enet_realize(DeviceState *dev, Error **errp)
{
    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
    stellaris_enet_state *s = STELLARIS_ENET(dev);

    memory_region_init_io(&s->mmio, OBJECT(s), &stellaris_enet_ops, s,
                          "stellaris_enet", 0x1000);
    sysbus_init_mmio(sbd, &s->mmio);
    sysbus_init_irq(sbd, &s->irq);
    qemu_macaddr_default_if_unset(&s->conf.macaddr);

    s->nic = qemu_new_nic(&net_stellaris_enet_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 Property stellaris_enet_properties[] = {
    DEFINE_NIC_PROPERTIES(stellaris_enet_state, conf),
    DEFINE_PROP_END_OF_LIST(),
};

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

    dc->realize = stellaris_enet_realize;
    dc->reset = stellaris_enet_reset;
    dc->props = stellaris_enet_properties;
    dc->vmsd = &vmstate_stellaris_enet;
}

static const TypeInfo stellaris_enet_info = {
    .name          = TYPE_STELLARIS_ENET,
    .parent        = TYPE_SYS_BUS_DEVICE,
    .instance_size = sizeof(stellaris_enet_state),
    .class_init    = stellaris_enet_class_init,
};

static void stellaris_enet_register_types(void)
{
    type_register_static(&stellaris_enet_info);
}

type_init(stellaris_enet_register_types)