Archipelago » qemu

/*

 * SMSC LAN9118 Ethernet interface emulation

 *

 * Copyright (c) 2009 CodeSourcery, LLC.

 * Written by Paul Brook

 *

 * This code is licensed under the GNU GPL v2

 *

 * Contributions after 2012-01-13 are licensed under the terms of the

 * GNU GPL, version 2 or (at your option) any later version.

 */

#include "sysbus.h"

#include "net.h"

#include "devices.h"

#include "sysemu.h"

#include "ptimer.h"

/* For crc32 */

#include <zlib.h>

//#define DEBUG_LAN9118

#ifdef DEBUG_LAN9118

#define DPRINTF(fmt, ...) \

do { printf("lan9118: " fmt , ## __VA_ARGS__); } while (0)

#define BADF(fmt, ...) \

do { hw_error("lan9118: error: " fmt , ## __VA_ARGS__);} while (0)

#else

#define DPRINTF(fmt, ...) do {} while(0)

#define BADF(fmt, ...) \

do { fprintf(stderr, "lan9118: error: " fmt , ## __VA_ARGS__);} while (0)

#endif

#define CSR_ID_REV      0x50

#define CSR_IRQ_CFG     0x54

#define CSR_INT_STS     0x58

#define CSR_INT_EN      0x5c

#define CSR_BYTE_TEST   0x64

#define CSR_FIFO_INT    0x68

#define CSR_RX_CFG      0x6c

#define CSR_TX_CFG      0x70

#define CSR_HW_CFG      0x74

#define CSR_RX_DP_CTRL  0x78

#define CSR_RX_FIFO_INF 0x7c

#define CSR_TX_FIFO_INF 0x80

#define CSR_PMT_CTRL    0x84

#define CSR_GPIO_CFG    0x88

#define CSR_GPT_CFG     0x8c

#define CSR_GPT_CNT     0x90

#define CSR_WORD_SWAP   0x98

#define CSR_FREE_RUN    0x9c

#define CSR_RX_DROP     0xa0

#define CSR_MAC_CSR_CMD 0xa4

#define CSR_MAC_CSR_DATA 0xa8

#define CSR_AFC_CFG     0xac

#define CSR_E2P_CMD     0xb0

#define CSR_E2P_DATA    0xb4

/* IRQ_CFG */

#define IRQ_INT         0x00001000

#define IRQ_EN          0x00000100

#define IRQ_POL         0x00000010

#define IRQ_TYPE        0x00000001

/* INT_STS/INT_EN */

#define SW_INT          0x80000000

#define TXSTOP_INT      0x02000000

#define RXSTOP_INT      0x01000000

#define RXDFH_INT       0x00800000

#define TX_IOC_INT      0x00200000

#define RXD_INT         0x00100000

#define GPT_INT         0x00080000

#define PHY_INT         0x00040000

#define PME_INT         0x00020000

#define TXSO_INT        0x00010000

#define RWT_INT         0x00008000

#define RXE_INT         0x00004000

#define TXE_INT         0x00002000

#define TDFU_INT        0x00000800

#define TDFO_INT        0x00000400

#define TDFA_INT        0x00000200

#define TSFF_INT        0x00000100

#define TSFL_INT        0x00000080

#define RXDF_INT        0x00000040

#define RDFL_INT        0x00000020

#define RSFF_INT        0x00000010

#define RSFL_INT        0x00000008

#define GPIO2_INT       0x00000004

#define GPIO1_INT       0x00000002

#define GPIO0_INT       0x00000001

#define RESERVED_INT    0x7c001000

#define MAC_CR          1

#define MAC_ADDRH       2

#define MAC_ADDRL       3

#define MAC_HASHH       4

#define MAC_HASHL       5

#define MAC_MII_ACC     6

#define MAC_MII_DATA    7

#define MAC_FLOW        8

#define MAC_VLAN1       9 /* TODO */

#define MAC_VLAN2       10 /* TODO */

#define MAC_WUFF        11 /* TODO */

#define MAC_WUCSR       12 /* TODO */

#define MAC_CR_RXALL    0x80000000

#define MAC_CR_RCVOWN   0x00800000

#define MAC_CR_LOOPBK   0x00200000

#define MAC_CR_FDPX     0x00100000

#define MAC_CR_MCPAS    0x00080000

#define MAC_CR_PRMS     0x00040000

#define MAC_CR_INVFILT  0x00020000

#define MAC_CR_PASSBAD  0x00010000

#define MAC_CR_HO       0x00008000

#define MAC_CR_HPFILT   0x00002000

#define MAC_CR_LCOLL    0x00001000

#define MAC_CR_BCAST    0x00000800

#define MAC_CR_DISRTY   0x00000400

#define MAC_CR_PADSTR   0x00000100

#define MAC_CR_BOLMT    0x000000c0

#define MAC_CR_DFCHK    0x00000020

#define MAC_CR_TXEN     0x00000008

#define MAC_CR_RXEN     0x00000004

#define MAC_CR_RESERVED 0x7f404213

#define PHY_INT_ENERGYON            0x80

#define PHY_INT_AUTONEG_COMPLETE    0x40

#define PHY_INT_FAULT               0x20

#define PHY_INT_DOWN                0x10

#define PHY_INT_AUTONEG_LP          0x08

#define PHY_INT_PARFAULT            0x04

#define PHY_INT_AUTONEG_PAGE        0x02

#define GPT_TIMER_EN    0x20000000

enum tx_state {

    TX_IDLE,

    TX_B,

    TX_DATA

};

typedef struct {

    /* state is a tx_state but we can't put enums in VMStateDescriptions. */

    uint32_t state;

    uint32_t cmd_a;

    uint32_t cmd_b;

    int32_t buffer_size;

    int32_t offset;

    int32_t pad;

    int32_t fifo_used;

    int32_t len;

    uint8_t data[2048];

} LAN9118Packet;

static const VMStateDescription vmstate_lan9118_packet = {

    .name = "lan9118_packet",

    .version_id = 1,

    .minimum_version_id = 1,

    .fields = (VMStateField[]) {

        VMSTATE_UINT32(state, LAN9118Packet),

        VMSTATE_UINT32(cmd_a, LAN9118Packet),

        VMSTATE_UINT32(cmd_b, LAN9118Packet),

        VMSTATE_INT32(buffer_size, LAN9118Packet),

        VMSTATE_INT32(offset, LAN9118Packet),

        VMSTATE_INT32(pad, LAN9118Packet),

        VMSTATE_INT32(fifo_used, LAN9118Packet),

        VMSTATE_INT32(len, LAN9118Packet),

        VMSTATE_UINT8_ARRAY(data, LAN9118Packet, 2048),

        VMSTATE_END_OF_LIST()

    }

};

typedef struct {

    SysBusDevice busdev;

    NICState *nic;

    NICConf conf;

    qemu_irq irq;

    MemoryRegion mmio;

    ptimer_state *timer;

    uint32_t irq_cfg;

    uint32_t int_sts;

    uint32_t int_en;

    uint32_t fifo_int;

    uint32_t rx_cfg;

    uint32_t tx_cfg;

    uint32_t hw_cfg;

    uint32_t pmt_ctrl;

    uint32_t gpio_cfg;

    uint32_t gpt_cfg;

    uint32_t word_swap;

    uint32_t free_timer_start;

    uint32_t mac_cmd;

    uint32_t mac_data;

    uint32_t afc_cfg;

    uint32_t e2p_cmd;

    uint32_t e2p_data;

    uint32_t mac_cr;

    uint32_t mac_hashh;

    uint32_t mac_hashl;

    uint32_t mac_mii_acc;

    uint32_t mac_mii_data;

    uint32_t mac_flow;

    uint32_t phy_status;

    uint32_t phy_control;

    uint32_t phy_advertise;

    uint32_t phy_int;

    uint32_t phy_int_mask;

    int32_t eeprom_writable;

    uint8_t eeprom[128];

    int32_t tx_fifo_size;

    LAN9118Packet *txp;

    LAN9118Packet tx_packet;

    int32_t tx_status_fifo_used;

    int32_t tx_status_fifo_head;

    uint32_t tx_status_fifo[512];

    int32_t rx_status_fifo_size;

    int32_t rx_status_fifo_used;

    int32_t rx_status_fifo_head;

    uint32_t rx_status_fifo[896];

    int32_t rx_fifo_size;

    int32_t rx_fifo_used;

    int32_t rx_fifo_head;

    uint32_t rx_fifo[3360];

    int32_t rx_packet_size_head;

    int32_t rx_packet_size_tail;

    int32_t rx_packet_size[1024];

    int32_t rxp_offset;

    int32_t rxp_size;

    int32_t rxp_pad;

} lan9118_state;

static const VMStateDescription vmstate_lan9118 = {

    .name = "lan9118",

    .version_id = 1,

    .minimum_version_id = 1,

    .fields = (VMStateField[]) {

        VMSTATE_PTIMER(timer, lan9118_state),

        VMSTATE_UINT32(irq_cfg, lan9118_state),

        VMSTATE_UINT32(int_sts, lan9118_state),

        VMSTATE_UINT32(int_en, lan9118_state),

        VMSTATE_UINT32(fifo_int, lan9118_state),

        VMSTATE_UINT32(rx_cfg, lan9118_state),

        VMSTATE_UINT32(tx_cfg, lan9118_state),

        VMSTATE_UINT32(hw_cfg, lan9118_state),

        VMSTATE_UINT32(pmt_ctrl, lan9118_state),

        VMSTATE_UINT32(gpio_cfg, lan9118_state),

        VMSTATE_UINT32(gpt_cfg, lan9118_state),

        VMSTATE_UINT32(word_swap, lan9118_state),

        VMSTATE_UINT32(free_timer_start, lan9118_state),

        VMSTATE_UINT32(mac_cmd, lan9118_state),

        VMSTATE_UINT32(mac_data, lan9118_state),

        VMSTATE_UINT32(afc_cfg, lan9118_state),

        VMSTATE_UINT32(e2p_cmd, lan9118_state),

        VMSTATE_UINT32(e2p_data, lan9118_state),

        VMSTATE_UINT32(mac_cr, lan9118_state),

        VMSTATE_UINT32(mac_hashh, lan9118_state),

        VMSTATE_UINT32(mac_hashl, lan9118_state),

        VMSTATE_UINT32(mac_mii_acc, lan9118_state),

        VMSTATE_UINT32(mac_mii_data, lan9118_state),

        VMSTATE_UINT32(mac_flow, lan9118_state),

        VMSTATE_UINT32(phy_status, lan9118_state),

        VMSTATE_UINT32(phy_control, lan9118_state),

        VMSTATE_UINT32(phy_advertise, lan9118_state),

        VMSTATE_UINT32(phy_int, lan9118_state),

        VMSTATE_UINT32(phy_int_mask, lan9118_state),

        VMSTATE_INT32(eeprom_writable, lan9118_state),

        VMSTATE_UINT8_ARRAY(eeprom, lan9118_state, 128),

        VMSTATE_INT32(tx_fifo_size, lan9118_state),

        /* txp always points at tx_packet so need not be saved */

        VMSTATE_STRUCT(tx_packet, lan9118_state, 0,

                       vmstate_lan9118_packet, LAN9118Packet),

        VMSTATE_INT32(tx_status_fifo_used, lan9118_state),

        VMSTATE_INT32(tx_status_fifo_head, lan9118_state),

        VMSTATE_UINT32_ARRAY(tx_status_fifo, lan9118_state, 512),

        VMSTATE_INT32(rx_status_fifo_size, lan9118_state),

        VMSTATE_INT32(rx_status_fifo_used, lan9118_state),

        VMSTATE_INT32(rx_status_fifo_head, lan9118_state),

        VMSTATE_UINT32_ARRAY(rx_status_fifo, lan9118_state, 896),

        VMSTATE_INT32(rx_fifo_size, lan9118_state),

        VMSTATE_INT32(rx_fifo_used, lan9118_state),

        VMSTATE_INT32(rx_fifo_head, lan9118_state),

        VMSTATE_UINT32_ARRAY(rx_fifo, lan9118_state, 3360),

        VMSTATE_INT32(rx_packet_size_head, lan9118_state),

        VMSTATE_INT32(rx_packet_size_tail, lan9118_state),

        VMSTATE_INT32_ARRAY(rx_packet_size, lan9118_state, 1024),

        VMSTATE_INT32(rxp_offset, lan9118_state),

        VMSTATE_INT32(rxp_size, lan9118_state),

        VMSTATE_INT32(rxp_pad, lan9118_state),

        VMSTATE_END_OF_LIST()

    }

};

static void lan9118_update(lan9118_state *s)

{

    int level;

    /* TODO: Implement FIFO level IRQs.  */

    level = (s->int_sts & s->int_en) != 0;

    if (level) {

        s->irq_cfg |= IRQ_INT;

    } else {

        s->irq_cfg &= ~IRQ_INT;

    }

    if ((s->irq_cfg & IRQ_EN) == 0) {

        level = 0;

    }

    if ((s->irq_cfg & (IRQ_TYPE | IRQ_POL)) != (IRQ_TYPE | IRQ_POL)) {

        /* Interrupt is active low unless we're configured as

         * active-high polarity, push-pull type.

         */

        level = !level;

    }

    qemu_set_irq(s->irq, level);

}

static void lan9118_mac_changed(lan9118_state *s)

{

    qemu_format_nic_info_str(&s->nic->nc, s->conf.macaddr.a);

}

static void lan9118_reload_eeprom(lan9118_state *s)

{

    int i;

    if (s->eeprom[0] != 0xa5) {

        s->e2p_cmd &= ~0x10;

        DPRINTF("MACADDR load failed\n");

        return;

    }

    for (i = 0; i < 6; i++) {

        s->conf.macaddr.a[i] = s->eeprom[i + 1];

    }

    s->e2p_cmd |= 0x10;

    DPRINTF("MACADDR loaded from eeprom\n");

    lan9118_mac_changed(s);

}

static void phy_update_irq(lan9118_state *s)

{

    if (s->phy_int & s->phy_int_mask) {

        s->int_sts |= PHY_INT;

    } else {

        s->int_sts &= ~PHY_INT;

    }

    lan9118_update(s);

}

static void phy_update_link(lan9118_state *s)

{

    /* Autonegotiation status mirrors link status.  */

    if (s->nic->nc.link_down) {

        s->phy_status &= ~0x0024;

        s->phy_int |= PHY_INT_DOWN;

    } else {

        s->phy_status |= 0x0024;

        s->phy_int |= PHY_INT_ENERGYON;

        s->phy_int |= PHY_INT_AUTONEG_COMPLETE;

    }

    phy_update_irq(s);

}

static void lan9118_set_link(VLANClientState *nc)

{

    phy_update_link(DO_UPCAST(NICState, nc, nc)->opaque);

}

static void phy_reset(lan9118_state *s)

{

    s->phy_status = 0x7809;

    s->phy_control = 0x3000;

    s->phy_advertise = 0x01e1;

    s->phy_int_mask = 0;

    s->phy_int = 0;

    phy_update_link(s);

}

static void lan9118_reset(DeviceState *d)

{

    lan9118_state *s = FROM_SYSBUS(lan9118_state, sysbus_from_qdev(d));

    s->irq_cfg &= (IRQ_TYPE | IRQ_POL);

    s->int_sts = 0;

    s->int_en = 0;

    s->fifo_int = 0x48000000;

    s->rx_cfg = 0;

    s->tx_cfg = 0;

    s->hw_cfg = 0x00050000;

    s->pmt_ctrl &= 0x45;

    s->gpio_cfg = 0;

    s->txp->fifo_used = 0;

    s->txp->state = TX_IDLE;

    s->txp->cmd_a = 0xffffffffu;

    s->txp->cmd_b = 0xffffffffu;

    s->txp->len = 0;

    s->txp->fifo_used = 0;

    s->tx_fifo_size = 4608;

    s->tx_status_fifo_used = 0;

    s->rx_status_fifo_size = 704;

    s->rx_fifo_size = 2640;

    s->rx_fifo_used = 0;

    s->rx_status_fifo_size = 176;

    s->rx_status_fifo_used = 0;

    s->rxp_offset = 0;

    s->rxp_size = 0;

    s->rxp_pad = 0;

    s->rx_packet_size_tail = s->rx_packet_size_head;

    s->rx_packet_size[s->rx_packet_size_head] = 0;

    s->mac_cmd = 0;

    s->mac_data = 0;

    s->afc_cfg = 0;

    s->e2p_cmd = 0;

    s->e2p_data = 0;

    s->free_timer_start = qemu_get_clock_ns(vm_clock) / 40;

    ptimer_stop(s->timer);

    ptimer_set_count(s->timer, 0xffff);

    s->gpt_cfg = 0xffff;

    s->mac_cr = MAC_CR_PRMS;

    s->mac_hashh = 0;

    s->mac_hashl = 0;

    s->mac_mii_acc = 0;

    s->mac_mii_data = 0;

    s->mac_flow = 0;

    phy_reset(s);

    s->eeprom_writable = 0;

    lan9118_reload_eeprom(s);

}

static int lan9118_can_receive(VLANClientState *nc)

{

    return 1;

}

static void rx_fifo_push(lan9118_state *s, uint32_t val)

{

    int fifo_pos;

    fifo_pos = s->rx_fifo_head + s->rx_fifo_used;

    if (fifo_pos >= s->rx_fifo_size)

      fifo_pos -= s->rx_fifo_size;

    s->rx_fifo[fifo_pos] = val;

    s->rx_fifo_used++;

}

/* Return nonzero if the packet is accepted by the filter.  */

static int lan9118_filter(lan9118_state *s, const uint8_t *addr)

{

    int multicast;

    uint32_t hash;

    if (s->mac_cr & MAC_CR_PRMS) {

        return 1;

    }

    if (addr[0] == 0xff && addr[1] == 0xff && addr[2] == 0xff &&

        addr[3] == 0xff && addr[4] == 0xff && addr[5] == 0xff) {

        return (s->mac_cr & MAC_CR_BCAST) == 0;

    }

    multicast = addr[0] & 1;

    if (multicast &&s->mac_cr & MAC_CR_MCPAS) {

        return 1;

    }

    if (multicast ? (s->mac_cr & MAC_CR_HPFILT) == 0

                  : (s->mac_cr & MAC_CR_HO) == 0) {

        /* Exact matching.  */

        hash = memcmp(addr, s->conf.macaddr.a, 6);

        if (s->mac_cr & MAC_CR_INVFILT) {

            return hash != 0;

        } else {

            return hash == 0;

        }

    } else {

        /* Hash matching  */

        hash = (crc32(~0, addr, 6) >> 26);

        if (hash & 0x20) {

            return (s->mac_hashh >> (hash & 0x1f)) & 1;

        } else {

            return (s->mac_hashl >> (hash & 0x1f)) & 1;

        }

    }

}

static ssize_t lan9118_receive(VLANClientState *nc, const uint8_t *buf,

                               size_t size)

{

    lan9118_state *s = DO_UPCAST(NICState, nc, nc)->opaque;

    int fifo_len;

    int offset;

    int src_pos;

    int n;

    int filter;

    uint32_t val;

    uint32_t crc;

    uint32_t status;

    if ((s->mac_cr & MAC_CR_RXEN) == 0) {

        return -1;

    }

    if (size >= 2048 || size < 14) {

        return -1;

    }

    /* TODO: Implement FIFO overflow notification.  */

    if (s->rx_status_fifo_used == s->rx_status_fifo_size) {

        return -1;

    }

    filter = lan9118_filter(s, buf);

    if (!filter && (s->mac_cr & MAC_CR_RXALL) == 0) {

        return size;

    }

    offset = (s->rx_cfg >> 8) & 0x1f;

    n = offset & 3;

    fifo_len = (size + n + 3) >> 2;

    /* Add a word for the CRC.  */

    fifo_len++;

    if (s->rx_fifo_size - s->rx_fifo_used < fifo_len) {

        return -1;

    }

    DPRINTF("Got packet len:%d fifo:%d filter:%s\n",

            (int)size, fifo_len, filter ? "pass" : "fail");

    val = 0;

    crc = bswap32(crc32(~0, buf, size));

    for (src_pos = 0; src_pos < size; src_pos++) {

        val = (val >> 8) | ((uint32_t)buf[src_pos] << 24);

        n++;

        if (n == 4) {

            n = 0;

            rx_fifo_push(s, val);

            val = 0;

        }

    }

    if (n) {

        val >>= ((4 - n) * 8);

        val |= crc << (n * 8);

        rx_fifo_push(s, val);

        val = crc >> ((4 - n) * 8);

        rx_fifo_push(s, val);

    } else {

        rx_fifo_push(s, crc);

    }

    n = s->rx_status_fifo_head + s->rx_status_fifo_used;

    if (n >= s->rx_status_fifo_size) {

        n -= s->rx_status_fifo_size;

    }

    s->rx_packet_size[s->rx_packet_size_tail] = fifo_len;

    s->rx_packet_size_tail = (s->rx_packet_size_tail + 1023) & 1023;

    s->rx_status_fifo_used++;

    status = (size + 4) << 16;

    if (buf[0] == 0xff && buf[1] == 0xff && buf[2] == 0xff &&

        buf[3] == 0xff && buf[4] == 0xff && buf[5] == 0xff) {

        status |= 0x00002000;

    } else if (buf[0] & 1) {

        status |= 0x00000400;

    }

    if (!filter) {

        status |= 0x40000000;

    }

    s->rx_status_fifo[n] = status;

    if (s->rx_status_fifo_used > (s->fifo_int & 0xff)) {

        s->int_sts |= RSFL_INT;

    }

    lan9118_update(s);

    return size;

}

static uint32_t rx_fifo_pop(lan9118_state *s)

{

    int n;

    uint32_t val;

    if (s->rxp_size == 0 && s->rxp_pad == 0) {

        s->rxp_size = s->rx_packet_size[s->rx_packet_size_head];

        s->rx_packet_size[s->rx_packet_size_head] = 0;

        if (s->rxp_size != 0) {

            s->rx_packet_size_head = (s->rx_packet_size_head + 1023) & 1023;

            s->rxp_offset = (s->rx_cfg >> 10) & 7;

            n = s->rxp_offset + s->rxp_size;

            switch (s->rx_cfg >> 30) {

            case 1:

                n = (-n) & 3;

                break;

            case 2:

                n = (-n) & 7;

                break;

            default:

                n = 0;

                break;

            }

            s->rxp_pad = n;

            DPRINTF("Pop packet size:%d offset:%d pad: %d\n",

                    s->rxp_size, s->rxp_offset, s->rxp_pad);

        }

    }

    if (s->rxp_offset > 0) {

        s->rxp_offset--;

        val = 0;

    } else if (s->rxp_size > 0) {

        s->rxp_size--;

        val = s->rx_fifo[s->rx_fifo_head++];

        if (s->rx_fifo_head >= s->rx_fifo_size) {

            s->rx_fifo_head -= s->rx_fifo_size;

        }

        s->rx_fifo_used--;

    } else if (s->rxp_pad > 0) {

        s->rxp_pad--;

        val =  0;

    } else {

        DPRINTF("RX underflow\n");

        s->int_sts |= RXE_INT;

        val =  0;

    }

    lan9118_update(s);

    return val;

}

static void do_tx_packet(lan9118_state *s)

{

    int n;

    uint32_t status;

    /* FIXME: Honor TX disable, and allow queueing of packets.  */

    if (s->phy_control & 0x4000)  {

        /* This assumes the receive routine doesn't touch the VLANClient.  */

        lan9118_receive(&s->nic->nc, s->txp->data, s->txp->len);

    } else {

        qemu_send_packet(&s->nic->nc, s->txp->data, s->txp->len);

    }

    s->txp->fifo_used = 0;

    if (s->tx_status_fifo_used == 512) {

        /* Status FIFO full */

        return;

    }

    /* Add entry to status FIFO.  */

    status = s->txp->cmd_b & 0xffff0000u;

    DPRINTF("Sent packet tag:%04x len %d\n", status >> 16, s->txp->len);

    n = (s->tx_status_fifo_head + s->tx_status_fifo_used) & 511;

    s->tx_status_fifo[n] = status;

    s->tx_status_fifo_used++;

    if (s->tx_status_fifo_used == 512) {

        s->int_sts |= TSFF_INT;

        /* TODO: Stop transmission.  */

    }

}

static uint32_t rx_status_fifo_pop(lan9118_state *s)

{

    uint32_t val;

    val = s->rx_status_fifo[s->rx_status_fifo_head];

    if (s->rx_status_fifo_used != 0) {

        s->rx_status_fifo_used--;

        s->rx_status_fifo_head++;

        if (s->rx_status_fifo_head >= s->rx_status_fifo_size) {

            s->rx_status_fifo_head -= s->rx_status_fifo_size;

        }

        /* ??? What value should be returned when the FIFO is empty?  */

        DPRINTF("RX status pop 0x%08x\n", val);

    }

    return val;

}

static uint32_t tx_status_fifo_pop(lan9118_state *s)

{

    uint32_t val;

    val = s->tx_status_fifo[s->tx_status_fifo_head];

    if (s->tx_status_fifo_used != 0) {

        s->tx_status_fifo_used--;

        s->tx_status_fifo_head = (s->tx_status_fifo_head + 1) & 511;

        /* ??? What value should be returned when the FIFO is empty?  */

    }

    return val;

}

static void tx_fifo_push(lan9118_state *s, uint32_t val)

{

    int n;

    if (s->txp->fifo_used == s->tx_fifo_size) {

        s->int_sts |= TDFO_INT;

        return;

    }

    switch (s->txp->state) {

    case TX_IDLE:

        s->txp->cmd_a = val & 0x831f37ff;

        s->txp->fifo_used++;

        s->txp->state = TX_B;

        break;

    case TX_B:

        if (s->txp->cmd_a & 0x2000) {

            /* First segment */

            s->txp->cmd_b = val;

            s->txp->fifo_used++;

            s->txp->buffer_size = s->txp->cmd_a & 0x7ff;

            s->txp->offset = (s->txp->cmd_a >> 16) & 0x1f;

            /* End alignment does not include command words.  */

            n = (s->txp->buffer_size + s->txp->offset + 3) >> 2;

            switch ((n >> 24) & 3) {

            case 1:

                n = (-n) & 3;

                break;

            case 2:

                n = (-n) & 7;

                break;

            default:

                n = 0;

            }

            s->txp->pad = n;

            s->txp->len = 0;

        }

        DPRINTF("Block len:%d offset:%d pad:%d cmd %08x\n",

                s->txp->buffer_size, s->txp->offset, s->txp->pad,

                s->txp->cmd_a);

        s->txp->state = TX_DATA;

        break;

    case TX_DATA:

        if (s->txp->offset >= 4) {

            s->txp->offset -= 4;

            break;

        }

        if (s->txp->buffer_size <= 0 && s->txp->pad != 0) {

            s->txp->pad--;

        } else {

            n = 4;

            while (s->txp->offset) {

                val >>= 8;

                n--;

                s->txp->offset--;

            }

            /* Documentation is somewhat unclear on the ordering of bytes

               in FIFO words.  Empirical results show it to be little-endian.

               */

            /* TODO: FIFO overflow checking.  */

            while (n--) {

                s->txp->data[s->txp->len] = val & 0xff;

                s->txp->len++;

                val >>= 8;

                s->txp->buffer_size--;

            }

            s->txp->fifo_used++;

        }

        if (s->txp->buffer_size <= 0 && s->txp->pad == 0) {

            if (s->txp->cmd_a & 0x1000) {

                do_tx_packet(s);

            }

            if (s->txp->cmd_a & 0x80000000) {

                s->int_sts |= TX_IOC_INT;

            }

            s->txp->state = TX_IDLE;

        }

        break;

    }

}

static uint32_t do_phy_read(lan9118_state *s, int reg)

{

    uint32_t val;

    switch (reg) {

    case 0: /* Basic Control */

        return s->phy_control;

    case 1: /* Basic Status */

        return s->phy_status;

    case 2: /* ID1 */

        return 0x0007;

    case 3: /* ID2 */

        return 0xc0d1;

    case 4: /* Auto-neg advertisement */

        return s->phy_advertise;

    case 5: /* Auto-neg Link Partner Ability */

        return 0x0f71;

    case 6: /* Auto-neg Expansion */

        return 1;

        /* TODO 17, 18, 27, 29, 30, 31 */

    case 29: /* Interrupt source.  */

        val = s->phy_int;

        s->phy_int = 0;

        phy_update_irq(s);

        return val;

    case 30: /* Interrupt mask */

        return s->phy_int_mask;

    default:

        BADF("PHY read reg %d\n", reg);

        return 0;

    }

}

static void do_phy_write(lan9118_state *s, int reg, uint32_t val)

{

    switch (reg) {

    case 0: /* Basic Control */

        if (val & 0x8000) {

            phy_reset(s);

            break;

        }

        s->phy_control = val & 0x7980;

        /* Complete autonegotiation immediately.  */

        if (val & 0x1000) {

            s->phy_status |= 0x0020;

        }

        break;

    case 4: /* Auto-neg advertisement */

        s->phy_advertise = (val & 0x2d7f) | 0x80;

        break;

        /* TODO 17, 18, 27, 31 */

    case 30: /* Interrupt mask */

        s->phy_int_mask = val & 0xff;

        phy_update_irq(s);

        break;

    default:

        BADF("PHY write reg %d = 0x%04x\n", reg, val);

    }

}

static void do_mac_write(lan9118_state *s, int reg, uint32_t val)

{

    switch (reg) {

    case MAC_CR:

        if ((s->mac_cr & MAC_CR_RXEN) != 0 && (val & MAC_CR_RXEN) == 0) {

            s->int_sts |= RXSTOP_INT;

        }

        s->mac_cr = val & ~MAC_CR_RESERVED;

        DPRINTF("MAC_CR: %08x\n", val);

        break;

    case MAC_ADDRH:

        s->conf.macaddr.a[4] = val & 0xff;

        s->conf.macaddr.a[5] = (val >> 8) & 0xff;

        lan9118_mac_changed(s);

        break;

    case MAC_ADDRL:

        s->conf.macaddr.a[0] = val & 0xff;

        s->conf.macaddr.a[1] = (val >> 8) & 0xff;

        s->conf.macaddr.a[2] = (val >> 16) & 0xff;

        s->conf.macaddr.a[3] = (val >> 24) & 0xff;

        lan9118_mac_changed(s);

        break;

    case MAC_HASHH:

        s->mac_hashh = val;

        break;

    case MAC_HASHL:

        s->mac_hashl = val;

        break;

    case MAC_MII_ACC:

        s->mac_mii_acc = val & 0xffc2;

        if (val & 2) {

            DPRINTF("PHY write %d = 0x%04x\n",

                    (val >> 6) & 0x1f, s->mac_mii_data);

            do_phy_write(s, (val >> 6) & 0x1f, s->mac_mii_data);

        } else {

            s->mac_mii_data = do_phy_read(s, (val >> 6) & 0x1f);

            DPRINTF("PHY read %d = 0x%04x\n",

                    (val >> 6) & 0x1f, s->mac_mii_data);

        }

        break;

    case MAC_MII_DATA:

        s->mac_mii_data = val & 0xffff;

        break;

    case MAC_FLOW:

        s->mac_flow = val & 0xffff0000;

        break;

    case MAC_VLAN1:

        /* Writing to this register changes a condition for

         * FrameTooLong bit in rx_status.  Since we do not set

         * FrameTooLong anyway, just ignore write to this.

         */

        break;

    default: