src/devices/dev_dec21143.c

/*
 *  Copyright (C) 2005-2006  Anders Gavare.  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. 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.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 *  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 *  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 *  OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 *  SUCH DAMAGE.
 *   
 *
 *  $Id: dev_dec21143.c,v 1.25 2006/03/04 12:38:47 debug Exp $
 *
 *  DEC 21143 ("Tulip") ethernet controller. Implemented from Intel document
 *  278074-001 ("21143 PC/CardBus 10/100Mb/s Ethernet LAN Controller") and by
 *  reverse-engineering OpenBSD and NetBSD sources.
 *
 *  This device emulates several sub-components:
 *
 *      21143:  This is the actual ethernet controller.
 *
 *      MII:    The "physical" network interface.
 *
 *      SROM:   A ROM area containing setting such as which MAC address to
 *              use, and info about the MII.
 *
 *
 *  TODO:
 *      o)  Handle _writes_ to MII registers.
 *      o)  Make it work with modern Linux kernels (as a guest OS).
 *      o)  Endianness for descriptors? If necessary.
 *      o)  Actually handle the "Setup" packet.
 *      o)  MAC filtering on incoming packets.
 *      o)  Don't hardcode as many values.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "cpu.h"
#include "device.h"
#include "devices.h"
#include "emul.h"
#include "machine.h"
#include "memory.h"
#include "misc.h"
#include "net.h"

#include "mii.h"
#include "tulipreg.h"


/*  #define debug fatal  */

#define DEC21143_TICK_SHIFT             16

#define N_REGS                  32
#define ROM_WIDTH               6

struct dec21143_data {
        int             irq_nr;
        int             irq_asserted;

        /*  PCI:  */
        int             pci_little_endian;

        /*  Ethernet address, and a network which we are connected to:  */
        uint8_t         mac[6];
        struct net      *net;

        /*  SROM emulation:  */
        uint8_t         srom[1 << (ROM_WIDTH + 1)];
        int             srom_curbit;
        int             srom_opcode;
        int             srom_opcode_has_started;
        int             srom_addr;

        /*  MII PHY emulation:  */
        uint16_t        mii_phy_reg[MII_NPHY * 32];
        int             mii_state;
        int             mii_bit;
        int             mii_opcode;
        int             mii_phyaddr;
        int             mii_regaddr;

        /*  21143 registers:  */
        uint32_t        reg[N_REGS];

        /*  Internal TX state:  */
        uint64_t        cur_tx_addr;
        unsigned char   *cur_tx_buf;
        int             cur_tx_buf_len;
        int             tx_idling;
        int             tx_idling_threshold;

        /*  Internal RX state:  */
        uint64_t        cur_rx_addr;
        unsigned char   *cur_rx_buf;
        int             cur_rx_buf_len;
        int             cur_rx_offset;
};


/*  Internal states during MII data stream decode:  */
#define MII_STATE_RESET                         0
#define MII_STATE_START_WAIT                    1
#define MII_STATE_READ_OP                       2
#define MII_STATE_READ_PHYADDR_REGADDR          3
#define MII_STATE_A                             4
#define MII_STATE_D                             5
#define MII_STATE_IDLE                          6


/*
 *  dec21143_rx():
 *
 *  Receive a packet. (If there is no current packet, then check for newly
 *  arrived ones. If the current packet couldn't be fully transfered the
 *  last time, then continue on that packet.)
 */
int dec21143_rx(struct cpu *cpu, struct dec21143_data *d)
{
        uint64_t addr = d->cur_rx_addr, bufaddr;
        unsigned char descr[16];
        uint32_t rdes0, rdes1, rdes2, rdes3;
        int bufsize, buf1_size, buf2_size, i, writeback_len = 4, to_xfer;

        /*  No current packet? Then check for new ones.  */
        if (d->cur_rx_buf == NULL) {
                /*  Nothing available? Then abort.  */
                if (!net_ethernet_rx_avail(d->net, d))
                        return 0;

                /*  Get the next packet into our buffer:  */
                net_ethernet_rx(d->net, d, &d->cur_rx_buf,
                    &d->cur_rx_buf_len);

                /*  Append a 4 byte CRC:  */
                d->cur_rx_buf_len += 4;
                d->cur_rx_buf = realloc(d->cur_rx_buf, d->cur_rx_buf_len);
                if (d->cur_rx_buf == NULL) {
                        fatal("dec21143_rx(): out of memory\n");
                        exit(1);
                }
                /*  Well... the CRC is just zeros, for now.  */
                memset(d->cur_rx_buf + d->cur_rx_buf_len - 4, 0, 4);

                d->cur_rx_offset = 0;
        }

        /*  fatal("{ dec21143_rx: base = 0x%08x }\n", (int)addr);  */
        addr &= 0x7fffffff;

        if (!cpu->memory_rw(cpu, cpu->mem, addr, descr, sizeof(uint32_t),
            MEM_READ, PHYSICAL | NO_EXCEPTIONS)) {
                fatal("[ dec21143_rx: memory_rw failed! ]\n");
                return 0;
        }

        rdes0 = descr[0] + (descr[1]<<8) + (descr[2]<<16) + (descr[3]<<24);

        /*  Only use descriptors owned by the 21143:  */
        if (!(rdes0 & TDSTAT_OWN)) {
                d->reg[CSR_STATUS/8] |= STATUS_RU;
                return 0;
        }

        if (!cpu->memory_rw(cpu, cpu->mem, addr + sizeof(uint32_t), descr +
            sizeof(uint32_t), sizeof(uint32_t) * 3, MEM_READ, PHYSICAL |
            NO_EXCEPTIONS)) {
                fatal("[ dec21143_rx: memory_rw failed! ]\n");
                return 0;
        }

        rdes1 = descr[4] + (descr[5]<<8) + (descr[6]<<16) + (descr[7]<<24);
        rdes2 = descr[8] + (descr[9]<<8) + (descr[10]<<16) + (descr[11]<<24);
        rdes3 = descr[12] + (descr[13]<<8) + (descr[14]<<16) + (descr[15]<<24);

        buf1_size = rdes1 & TDCTL_SIZE1;
        buf2_size = (rdes1 & TDCTL_SIZE2) >> TDCTL_SIZE2_SHIFT;
        bufaddr = buf1_size? rdes2 : rdes3;
        bufsize = buf1_size? buf1_size : buf2_size;

        d->reg[CSR_STATUS/8] &= ~STATUS_RS;

        if (rdes1 & TDCTL_ER)
                d->cur_rx_addr = d->reg[CSR_RXLIST / 8];
        else {
                if (rdes1 & TDCTL_CH)
                        d->cur_rx_addr = rdes3;
                else
                        d->cur_rx_addr += 4 * sizeof(uint32_t);
        }

        debug("{ RX (%llx): 0x%08x 0x%08x 0x%x 0x%x: buf %i bytes at 0x%x }\n",
            (long long)addr, rdes0, rdes1, rdes2, rdes3, bufsize, (int)bufaddr);
        bufaddr &= 0x7fffffff;

        /*  Turn off all status bits, and give up ownership:  */
        rdes0 = 0x00000000;

        to_xfer = d->cur_rx_buf_len - d->cur_rx_offset;
        if (to_xfer > bufsize)
                to_xfer = bufsize;

        /*  DMA bytes from the packet into emulated physical memory:  */
        for (i=0; i<to_xfer; i++) {
                cpu->memory_rw(cpu, cpu->mem, bufaddr + i,
                    d->cur_rx_buf + d->cur_rx_offset + i, 1, MEM_WRITE,
                    PHYSICAL | NO_EXCEPTIONS);
                /*  fatal(" %02x", d->cur_rx_buf[d->cur_rx_offset + i]);  */
        }

        /*  Was this the first buffer in a frame? Then mark it as such.  */
        if (d->cur_rx_offset == 0)
                rdes0 |= TDSTAT_Rx_FS;

        d->cur_rx_offset += to_xfer;

        /*  Frame completed?  */
        if (d->cur_rx_offset >= d->cur_rx_buf_len) {
                rdes0 |= TDSTAT_Rx_LS;

                /*  Set the frame length:  */
                rdes0 |= (d->cur_rx_buf_len << 16) & TDSTAT_Rx_FL;

                /*  Frame too long? (1518 is max ethernet frame length)  */
                if (d->cur_rx_buf_len > 1518)
                        rdes0 |= TDSTAT_Rx_TL;

                /*  Cause a receiver interrupt:  */
                d->reg[CSR_STATUS/8] |= STATUS_RI;

                free(d->cur_rx_buf);
                d->cur_rx_buf = NULL;
                d->cur_rx_buf_len = 0;
        }

        /*  Descriptor writeback:  */
        descr[ 0] = rdes0;       descr[ 1] = rdes0 >> 8;
        descr[ 2] = rdes0 >> 16; descr[ 3] = rdes0 >> 24;
        if (writeback_len > 1) {
                descr[ 4] = rdes1;       descr[ 5] = rdes1 >> 8;
                descr[ 6] = rdes1 >> 16; descr[ 7] = rdes1 >> 24;
                descr[ 8] = rdes2;       descr[ 9] = rdes2 >> 8;
                descr[10] = rdes2 >> 16; descr[11] = rdes2 >> 24;
                descr[12] = rdes3;       descr[13] = rdes3 >> 8;
                descr[14] = rdes3 >> 16; descr[15] = rdes3 >> 24;
        }

        if (!cpu->memory_rw(cpu, cpu->mem, addr, descr, sizeof(uint32_t)
            * writeback_len, MEM_WRITE, PHYSICAL | NO_EXCEPTIONS)) {
                fatal("[ dec21143_rx: memory_rw failed! ]\n");
                return 0;
        }

        return 1;
}


/*
 *  dec21143_tx():
 *
 *  Transmit a packet, if the guest OS has marked a descriptor as containing
 *  data to transmit.
 */
int dec21143_tx(struct cpu *cpu, struct dec21143_data *d)
{
        uint64_t addr = d->cur_tx_addr, bufaddr;
        unsigned char descr[16];
        uint32_t tdes0, tdes1, tdes2, tdes3;
        int bufsize, buf1_size, buf2_size, i, writeback_len = 4;

        addr &= 0x7fffffff;

        if (!cpu->memory_rw(cpu, cpu->mem, addr, descr, sizeof(uint32_t),
            MEM_READ, PHYSICAL | NO_EXCEPTIONS)) {
                fatal("[ dec21143_tx: memory_rw failed! ]\n");
                return 0;
        }

        tdes0 = descr[0] + (descr[1]<<8) + (descr[2]<<16) + (descr[3]<<24);

        /*  fatal("{ dec21143_tx: base=0x%08x, tdes0=0x%08x }\n",
            (int)addr, (int)tdes0);  */

        /*  Only process packets owned by the 21143:  */
        if (!(tdes0 & TDSTAT_OWN)) {
                if (d->tx_idling > d->tx_idling_threshold) {
                        d->reg[CSR_STATUS/8] |= STATUS_TU;
                        d->tx_idling = 0;
                } else
                        d->tx_idling ++;
                return 0;
        }

        if (!cpu->memory_rw(cpu, cpu->mem, addr + sizeof(uint32_t), descr +
            sizeof(uint32_t), sizeof(uint32_t) * 3, MEM_READ, PHYSICAL |
            NO_EXCEPTIONS)) {
                fatal("[ dec21143_tx: memory_rw failed! ]\n");
                return 0;
        }

        tdes1 = descr[4] + (descr[5]<<8) + (descr[6]<<16) + (descr[7]<<24);
        tdes2 = descr[8] + (descr[9]<<8) + (descr[10]<<16) + (descr[11]<<24);
        tdes3 = descr[12] + (descr[13]<<8) + (descr[14]<<16) + (descr[15]<<24);

        buf1_size = tdes1 & TDCTL_SIZE1;
        buf2_size = (tdes1 & TDCTL_SIZE2) >> TDCTL_SIZE2_SHIFT;
        bufaddr = buf1_size? tdes2 : tdes3;
        bufsize = buf1_size? buf1_size : buf2_size;

        d->reg[CSR_STATUS/8] &= ~STATUS_TS;

        if (tdes1 & TDCTL_ER)
                d->cur_tx_addr = d->reg[CSR_TXLIST / 8];
        else {
                if (tdes1 & TDCTL_CH)
                        d->cur_tx_addr = tdes3;
                else
                        d->cur_tx_addr += 4 * sizeof(uint32_t);
        }

        fatal("{ TX (%llx): 0x%08x 0x%08x 0x%x 0x%x: buf %i bytes at 0x%x }\n",
            (long long)addr, tdes0, tdes1, tdes2, tdes3, bufsize, (int)bufaddr);
        bufaddr &= 0x7fffffff;

        /*  Assume no error:  */
        tdes0 &= ~ (TDSTAT_Tx_UF | TDSTAT_Tx_EC | TDSTAT_Tx_LC
            | TDSTAT_Tx_NC | TDSTAT_Tx_LO | TDSTAT_Tx_TO | TDSTAT_ES);

        if (tdes1 & TDCTL_Tx_SET) {
                /*
                 *  Setup Packet.
                 *
                 *  TODO. For now, just ignore it, and pretend it worked.
                 */
                /*  fatal("{ TX: setup packet }\n");  */
                if (bufsize != 192)
                        fatal("[ dec21143: setup packet len = %i, should be"
                            " 192! ]\n", (int)bufsize);
                if (tdes1 & TDCTL_Tx_IC)
                        d->reg[CSR_STATUS/8] |= STATUS_TI;
                /*  New descriptor values, according to the docs:  */
                tdes0 = 0x7fffffff; tdes1 = 0xffffffff;
                tdes2 = 0xffffffff; tdes3 = 0xffffffff;
        } else {
                /*
                 *  Data Packet.
                 */
                /*  fatal("{ TX: data packet: ");  */
                if (tdes1 & TDCTL_Tx_FS) {
                        /*  First segment. Let's allocate a new buffer:  */
                        /*  fatal("new frame }\n");  */
                        d->cur_tx_buf = malloc(bufsize);
                        d->cur_tx_buf_len = 0;
                } else {
                        /*  Not first segment. Increase the length of
                            the current buffer:  */
                        /*  fatal("continuing last frame }\n");  */
                        d->cur_tx_buf = realloc(d->cur_tx_buf,
                            d->cur_tx_buf_len + bufsize);
                }

                if (d->cur_tx_buf == NULL) {
                        fatal("dec21143_tx(): out of memory\n");
                        exit(1);
                }

                /*  "DMA" data from emulated physical memory into the buf:  */
                for (i=0; i<bufsize; i++) {
                        cpu->memory_rw(cpu, cpu->mem, bufaddr + i,
                            d->cur_tx_buf + d->cur_tx_buf_len + i, 1, MEM_READ,
                            PHYSICAL | NO_EXCEPTIONS);
                        /*  fatal(" %02x", d->cur_tx_buf[
                            d->cur_tx_buf_len + i]);  */
                }

                d->cur_tx_buf_len += bufsize;

                /*  Last segment? Then actually transmit it:  */
                if (tdes1 & TDCTL_Tx_LS) {
                        /*  fatal("{ TX: data frame complete. }\n");  */
                        if (d->net != NULL) {
                                net_ethernet_tx(d->net, d, d->cur_tx_buf,
                                    d->cur_tx_buf_len);
                        } else {
                                static int warn = 0;
                                if (!warn)
                                        fatal("[ dec21143: WARNING! Not "
                                            "connected to a network! ]\n");
                                warn = 1;
                        }

                        free(d->cur_tx_buf);
                        d->cur_tx_buf = NULL;
                        d->cur_tx_buf_len = 0;

                        /*  TODO: Shouldn't the OWN bit be cleared on all
                            kinds of segments, not just the Last?  */

                        /*  We are done.  */
                        tdes0 &= ~TDSTAT_OWN;
                        writeback_len = 1;

                        /*  Interrupt, if Tx_IC is set:  */
                        if (tdes1 & TDCTL_Tx_IC)
                                d->reg[CSR_STATUS/8] |= STATUS_TI;
                }
        }

        /*  Error summary:  */
        if (tdes0 & (TDSTAT_Tx_UF | TDSTAT_Tx_EC | TDSTAT_Tx_LC
            | TDSTAT_Tx_NC | TDSTAT_Tx_LO | TDSTAT_Tx_TO))
                tdes0 |= TDSTAT_ES;

        /*  Descriptor writeback:  */
        descr[ 0] = tdes0;       descr[ 1] = tdes0 >> 8;
        descr[ 2] = tdes0 >> 16; descr[ 3] = tdes0 >> 24;
        if (writeback_len > 1) {
                descr[ 4] = tdes1;       descr[ 5] = tdes1 >> 8;
                descr[ 6] = tdes1 >> 16; descr[ 7] = tdes1 >> 24;
                descr[ 8] = tdes2;       descr[ 9] = tdes2 >> 8;
                descr[10] = tdes2 >> 16; descr[11] = tdes2 >> 24;
                descr[12] = tdes3;       descr[13] = tdes3 >> 8;
                descr[14] = tdes3 >> 16; descr[15] = tdes3 >> 24;
        }

        if (!cpu->memory_rw(cpu, cpu->mem, addr, descr, sizeof(uint32_t)
            * writeback_len, MEM_WRITE, PHYSICAL | NO_EXCEPTIONS)) {
                fatal("[ dec21143_tx: memory_rw failed! ]\n");
                return 0;
        }

        return 1;
}


/*
 *  dev_dec21143_tick():
 */
void dev_dec21143_tick(struct cpu *cpu, void *extra)
{
        struct dec21143_data *d = extra;
        int asserted;

        if (d->reg[CSR_OPMODE / 8] & OPMODE_ST)
                while (dec21143_tx(cpu, d))
                        ;

        if (d->reg[CSR_OPMODE / 8] & OPMODE_SR)
                while (dec21143_rx(cpu, d))
                        ;

        /*  Normal and Abnormal interrupt summary:  */
        d->reg[CSR_STATUS / 8] &= ~(STATUS_NIS | STATUS_AIS);
        if (d->reg[CSR_STATUS / 8] & 0x00004845)
                d->reg[CSR_STATUS / 8] |= STATUS_NIS;
        if (d->reg[CSR_STATUS / 8] & 0x0c0037ba)
                d->reg[CSR_STATUS / 8] |= STATUS_AIS;

        asserted = d->reg[CSR_STATUS / 8] & d->reg[CSR_INTEN / 8] & 0x0c01ffff;
        if (asserted) {
                cpu_interrupt(cpu, d->irq_nr);
        } else {
                if (d->irq_asserted)
                        cpu_interrupt_ack(cpu, d->irq_nr);
        }

        /*  Remember assertion flag:  */
        d->irq_asserted = asserted;
}


/*
 *  mii_access():
 *
 *  This function handles accesses to the MII. Data streams seem to be of the
 *  following format:
 *
 *      vv---- starting delimiter
 *  ... 01 xx yyyyy zzzzz a[a] dddddddddddddddd
 *         ^---- I am starting with mii_bit = 0 here
 *
 *  where x = opcode (10 = read, 01 = write)
 *        y = PHY address
 *        z = register address
 *        a = on Reads: ACK bit (returned, should be 0)
 *            on Writes: _TWO_ dummy bits (10)
 *        d = 16 bits of data (MSB first)
 */
static void mii_access(struct cpu *cpu, struct dec21143_data *d,
        uint32_t oldreg, uint32_t idata)
{
        int obit, ibit = 0;
        uint16_t tmp;

        /*  Only care about data during clock cycles:  */
        if (!(idata & MIIROM_MDC))
                return;

        if (idata & MIIROM_MDC && oldreg & MIIROM_MDC)
                return;

        /*  fatal("[ mii_access(): 0x%08x ]\n", (int)idata);  */

        if (idata & MIIROM_BR) {
                fatal("[ mii_access(): MIIROM_BR: TODO ]\n");
                return;
        }

        obit = idata & MIIROM_MDO? 1 : 0;

        if (d->mii_state >= MII_STATE_START_WAIT &&
            d->mii_state <= MII_STATE_READ_PHYADDR_REGADDR &&
            idata & MIIROM_MIIDIR)
                fatal("[ mii_access(): bad dir? ]\n");

        switch (d->mii_state) {

        case MII_STATE_RESET:
                /*  Wait for a starting delimiter (0 followed by 1).  */
                if (obit)
                        return;
                if (idata & MIIROM_MIIDIR)
                        return;
                /*  fatal("[ mii_access(): got a 0 delimiter ]\n");  */
                d->mii_state = MII_STATE_START_WAIT;
                d->mii_opcode = 0;
                d->mii_phyaddr = 0;
                d->mii_regaddr = 0;
                break;

        case MII_STATE_START_WAIT:
                /*  Wait for a starting delimiter (0 followed by 1).  */
                if (!obit)
                        return;
                if (idata & MIIROM_MIIDIR) {
                        d->mii_state = MII_STATE_RESET;
                        return;
                }
                /*  fatal("[ mii_access(): got a 1 delimiter ]\n");  */
                d->mii_state = MII_STATE_READ_OP;
                d->mii_bit = 0;
                break;

        case MII_STATE_READ_OP:
                if (d->mii_bit == 0) {
                        d->mii_opcode = obit << 1;
                        /*  fatal("[ mii_access(): got first opcode bit "
                            "(%i) ]\n", obit);  */
                } else {
                        d->mii_opcode |= obit;
                        /*  fatal("[ mii_access(): got opcode = %i ]\n",
                            d->mii_opcode);  */
                        d->mii_state = MII_STATE_READ_PHYADDR_REGADDR;
                }
                d->mii_bit ++;
                break;

        case MII_STATE_READ_PHYADDR_REGADDR:
                /*  fatal("[ mii_access(): got phy/reg addr bit nr %i (%i)"
                    " ]\n", d->mii_bit - 2, obit);  */
                if (d->mii_bit <= 6)
                        d->mii_phyaddr |= obit << (6-d->mii_bit);
                else
                        d->mii_regaddr |= obit << (11-d->mii_bit);
                d->mii_bit ++;
                if (d->mii_bit >= 12) {
                        /*  fatal("[ mii_access(): phyaddr=0x%x regaddr=0x"
                            "%x ]\n", d->mii_phyaddr, d->mii_regaddr);  */
                        d->mii_state = MII_STATE_A;
                }
                break;

        case MII_STATE_A:
                switch (d->mii_opcode) {
                case MII_COMMAND_WRITE:
                        if (d->mii_bit >= 13)
                                d->mii_state = MII_STATE_D;
                        break;
                case MII_COMMAND_READ:
                        ibit = 0;
                        d->mii_state = MII_STATE_D;
                        break;
                default:debug("[ mii_access(): UNIMPLEMENTED MII opcode "
                            "%i (probably just a bug in GXemul's "
                            "MII data stream handling) ]\n", d->mii_opcode);
                        d->mii_state = MII_STATE_RESET;
                }
                d->mii_bit ++;
                break;

        case MII_STATE_D:
                switch (d->mii_opcode) {
                case MII_COMMAND_WRITE:
                        if (idata & MIIROM_MIIDIR)
                                fatal("[ mii_access(): write: bad dir? ]\n");
                        obit = obit? (0x8000 >> (d->mii_bit - 14)) : 0;
                        tmp = d->mii_phy_reg[(d->mii_phyaddr << 5) +
                            d->mii_regaddr] | obit;
                        if (d->mii_bit >= 29) {
                                d->mii_state = MII_STATE_IDLE;
                                debug("[ mii_access(): WRITE to phyaddr=0x%x "
                                    "regaddr=0x%x: 0x%04x ]\n", d->mii_phyaddr,
                                    d->mii_regaddr, tmp);
                        }
                        break;
                case MII_COMMAND_READ:
                        if (!(idata & MIIROM_MIIDIR))
                                break;
                        tmp = d->mii_phy_reg[(d->mii_phyaddr << 5) +
                            d->mii_regaddr];
                        if (d->mii_bit == 13)
                                debug("[ mii_access(): READ phyaddr=0x%x "
                                    "regaddr=0x%x: 0x%04x ]\n", d->mii_phyaddr,
                                    d->mii_regaddr, tmp);
                        ibit = tmp & (0x8000 >> (d->mii_bit - 13));
                        if (d->mii_bit >= 28)
                                d->mii_state = MII_STATE_IDLE;
                        break;
                }
                d->mii_bit ++;
                break;

        case MII_STATE_IDLE:
                d->mii_bit ++;
                if (d->mii_bit >= 31)
                        d->mii_state = MII_STATE_RESET;
                break;
        }

        d->reg[CSR_MIIROM / 8] &= ~MIIROM_MDI;
        if (ibit)
                d->reg[CSR_MIIROM / 8] |= MIIROM_MDI;
}


/*
 *  srom_access():
 *
 *  This function handles reads from the Ethernet Address ROM. This is not a
 *  100% correct implementation, as it was reverse-engineered from OpenBSD
 *  sources; it seems to work with OpenBSD, NetBSD, and Linux, though.
 *
 *  Each transfer (if I understood this correctly) is of the following format:
 *
 *      1xx yyyyyy zzzzzzzzzzzzzzzz
 *
 *  where 1xx    = operation (6 means a Read),
 *        yyyyyy = ROM address
 *        zz...z = data
 *
 *  y and z are _both_ read and written to at the same time; this enables the
 *  operating system to sense the number of bits in y (when reading, all y bits
 *  are 1 except the last one).
 */
static void srom_access(struct cpu *cpu, struct dec21143_data *d,
        uint32_t oldreg, uint32_t idata)
{
        int obit, ibit;

        /*  debug("CSR9 WRITE! 0x%08x\n", (int)idata);  */

        /*  New selection? Then reset internal state.  */
        if (idata & MIIROM_SR && !(oldreg & MIIROM_SR)) {
                d->srom_curbit = 0;
                d->srom_opcode = 0;
                d->srom_opcode_has_started = 0;
                d->srom_addr = 0;
        }

        /*  Only care about data during clock cycles:  */
        if (!(idata & MIIROM_SROMSK))
                return;

        obit = 0;
        ibit = idata & MIIROM_SROMDI? 1 : 0;
        /*  debug("CLOCK CYCLE! (bit %i): ", d->srom_curbit);  */

        /*
         *  Linux sends more zeroes before starting the actual opcode, than
         *  OpenBSD and NetBSD. Hopefully this is correct. (I'm just guessing
         *  that all opcodes should start with a 1, perhaps that's not really
         *  the case.)
         */
        if (!ibit && !d->srom_opcode_has_started)
                return;

        if (d->srom_curbit < 3) {
                d->srom_opcode_has_started = 1;
                d->srom_opcode <<= 1;
                d->srom_opcode |= ibit;
                /*  debug("opcode input '%i'\n", ibit);  */
        } else {
                switch (d->srom_opcode) {
                case TULIP_SROM_OPC_READ:
                        if (d->srom_curbit < ROM_WIDTH + 3) {
                                obit = d->srom_curbit < ROM_WIDTH + 2;
                                d->srom_addr <<= 1;
                                d->srom_addr |= ibit;
                        } else {
                                uint16_t romword = d->srom[d->srom_addr*2]
                                    + (d->srom[d->srom_addr*2+1] << 8);
                                if (d->srom_curbit == ROM_WIDTH + 3)
                                        debug("[ dec21143: ROM read from offset"
                                            " 0x%03x: 0x%04x ]\n",
                                            d->srom_addr, romword);
                                obit = romword & (0x8000 >>
                                    (d->srom_curbit - ROM_WIDTH - 3))? 1 : 0;
                        }
                        break;
                default:fatal("[ dec21243: unimplemented SROM/EEPROM "
                            "opcode %i ]\n", d->srom_opcode);
                }
                d->reg[CSR_MIIROM / 8] &= ~MIIROM_SROMDO;
                if (obit)
                        d->reg[CSR_MIIROM / 8] |= MIIROM_SROMDO;
                /*  debug("input '%i', output '%i'\n", ibit, obit);  */
        }

        d->srom_curbit ++;

        /*
         *  Done opcode + addr + data? Then restart. (At least NetBSD does
         *  sequential reads without turning selection off and then on.)
         */
        if (d->srom_curbit >= 3 + ROM_WIDTH + 16) {
                d->srom_curbit = 0;
                d->srom_opcode = 0;
                d->srom_opcode_has_started = 0;
                d->srom_addr = 0;
        }
}


/*
 *  dec21143_reset():
 *
 *  Set the 21143 registers, SROM, and MII data to reasonable values.
 */
static void dec21143_reset(struct cpu *cpu, struct dec21143_data *d)
{
        int leaf;

        if (d->cur_rx_buf != NULL)
                free(d->cur_rx_buf);
        if (d->cur_tx_buf != NULL)
                free(d->cur_tx_buf);
        d->cur_rx_buf = d->cur_tx_buf = NULL;

        memset(d->reg, 0, sizeof(uint32_t) * N_REGS);
        memset(d->srom, 0, sizeof(d->srom));
        memset(d->mii_phy_reg, 0, sizeof(d->mii_phy_reg));

        /*  Register values at reset, according to the manual:  */
        d->reg[CSR_BUSMODE / 8] = 0xfe000000;   /*  csr0   */
        d->reg[CSR_MIIROM  / 8] = 0xfff483ff;   /*  csr9   */
        d->reg[CSR_SIACONN / 8] = 0xffff0000;   /*  csr13  */
        d->reg[CSR_SIATXRX / 8] = 0xffffffff;   /*  csr14  */
        d->reg[CSR_SIAGEN  / 8] = 0x8ff00000;   /*  csr15  */

        d->tx_idling_threshold = 10;
        d->cur_rx_addr = d->cur_tx_addr = 0;

        /*  Version (= 1) and Chip count (= 1):  */
        d->srom[TULIP_ROM_SROM_FORMAT_VERION] = 1;
        d->srom[TULIP_ROM_CHIP_COUNT] = 1;

        /*  Set the MAC address:  */
        memcpy(d->srom + TULIP_ROM_IEEE_NETWORK_ADDRESS, d->mac, 6);

        leaf = 30;
        d->srom[TULIP_ROM_CHIPn_DEVICE_NUMBER(0)] = 0;
        d->srom[TULIP_ROM_CHIPn_INFO_LEAF_OFFSET(0)] = leaf & 255;
        d->srom[TULIP_ROM_CHIPn_INFO_LEAF_OFFSET(0)+1] = leaf >> 8;

        d->srom[leaf+TULIP_ROM_IL_SELECT_CONN_TYPE] = 0; /*  Not used?  */
        d->srom[leaf+TULIP_ROM_IL_MEDIA_COUNT] = 2;
        leaf += TULIP_ROM_IL_MEDIAn_BLOCK_BASE;

        d->srom[leaf] = 7;      /*  descriptor length  */
        d->srom[leaf+1] = TULIP_ROM_MB_21142_SIA;
        d->srom[leaf+2] = TULIP_ROM_MB_MEDIA_100TX;
        /*  here comes 4 bytes of GPIO control/data settings  */
        leaf += d->srom[leaf];

        d->srom[leaf] = 15;     /*  descriptor length  */
        d->srom[leaf+1] = TULIP_ROM_MB_21142_MII;
        d->srom[leaf+2] = 0;    /*  PHY nr  */
        d->srom[leaf+3] = 0;    /*  len of select sequence  */
        d->srom[leaf+4] = 0;    /*  len of reset sequence  */
        /*  5,6, 7,8, 9,10, 11,12, 13,14 = unused by GXemul  */
        leaf += d->srom[leaf];

        /*  MII PHY initial state:  */
        d->mii_state = MII_STATE_RESET;

        /*  PHY #0:  */
        d->mii_phy_reg[MII_BMSR] = BMSR_100TXFDX | BMSR_10TFDX |
            BMSR_ACOMP | BMSR_ANEG | BMSR_LINK;
}


/*
 *  dev_dec21143_access():
 */
DEVICE_ACCESS(dec21143)
{
        struct dec21143_data *d = extra;
        uint64_t idata = 0, odata = 0;
        uint32_t oldreg = 0;
        int regnr = relative_addr >> 3;

        if (writeflag == MEM_WRITE)
                idata = memory_readmax64(cpu, data, len | d->pci_little_endian);

        if ((relative_addr & 7) == 0 && regnr < N_REGS) {
                if (writeflag == MEM_READ) {
                        odata = d->reg[regnr];
                } else {
                        oldreg = d->reg[regnr];
                        switch (regnr) {
                        case CSR_STATUS / 8:    /*  Zero-on-write  */
                                d->reg[regnr] &= ~(idata & 0x0c01ffff);
                                break;
                        case CSR_MISSED / 8:    /*  Read only  */
                                break;
                        default:d->reg[regnr] = idata;
                        }
                }
        } else
                fatal("[ dec21143: WARNING! unaligned access (0x%x) ]\n",
                    (int)relative_addr);

        switch (relative_addr) {

        case CSR_BUSMODE:       /*  csr0  */
                if (writeflag == MEM_WRITE) {
                        /*  Software reset takes effect immediately.  */
                        if (idata & BUSMODE_SWR) {
                                dec21143_reset(cpu, d);
                                idata &= ~BUSMODE_SWR;
                        }
                }
                break;

        case CSR_TXPOLL:        /*  csr1  */
                if (writeflag == MEM_READ)
                        fatal("[ dec21143: UNIMPLEMENTED READ from "
                            "txpoll ]\n");
                d->tx_idling = d->tx_idling_threshold;
                dev_dec21143_tick(cpu, extra);
                break;

        case CSR_RXPOLL:        /*  csr2  */
                if (writeflag == MEM_READ)
                        fatal("[ dec21143: UNIMPLEMENTED READ from "
                            "rxpoll ]\n");
                dev_dec21143_tick(cpu, extra);
                break;

        case CSR_RXLIST:        /*  csr3  */
                if (writeflag == MEM_WRITE) {
                        debug("[ dec21143: setting RXLIST to 0x%x ]\n",
                            (int)idata);
                        if (idata & 0x3)
                                fatal("[ dec21143: WARNING! RXLIST not aligned"
                                    "? (0x%llx) ]\n", (long long)idata);
                        idata &= ~0x3;
                        d->cur_rx_addr = idata;
                }
                break;

        case CSR_TXLIST:        /*  csr4  */
                if (writeflag == MEM_WRITE) {
                        debug("[ dec21143: setting TXLIST to 0x%x ]\n",
                            (int)idata);
                        if (idata & 0x3)
                                fatal("[ dec21143: WARNING! TXLIST not aligned"
                                    "? (0x%llx) ]\n", (long long)idata);
                        idata &= ~0x3;
                        d->cur_tx_addr = idata;
                }
                break;

        case CSR_STATUS:        /*  csr5  */
        case CSR_INTEN:         /*  csr7  */
                if (writeflag == MEM_WRITE) {
                        /*  Recalculate interrupt assertion.  */
                        dev_dec21143_tick(cpu, extra);
                }
                break;

        case CSR_OPMODE:        /*  csr6:  */
                if (writeflag == MEM_WRITE) {
                        if (idata & 0x02000000) {
                                /*  A must-be-one bit.  */
                                idata &= ~0x02000000;
                        }
                        if (idata & OPMODE_ST) {
                                idata &= ~OPMODE_ST;
                        } else {
                                /*  Turned off TX? Then idle:  */
                                d->reg[CSR_STATUS/8] |= STATUS_TPS;
                        }
                        if (idata & OPMODE_SR) {
                                idata &= ~OPMODE_SR;
                        } else {
                                /*  Turned off RX? Then go to stopped state:  */
                                d->reg[CSR_STATUS/8] &= ~STATUS_RS;
                        }
                        idata &= ~(OPMODE_HBD | OPMODE_SCR | OPMODE_PCS
                            | OPMODE_PS | OPMODE_SF | OPMODE_TTM | OPMODE_FD);
                        if (idata & OPMODE_PNIC_IT) {
                                idata &= ~OPMODE_PNIC_IT;
                                d->tx_idling = d->tx_idling_threshold;
                        }
                        if (idata != 0) {
                                fatal("[ dec21143: UNIMPLEMENTED OPMODE bits"
                                    ": 0x%08x ]\n", (int)idata);
                        }
                        dev_dec21143_tick(cpu, extra);
                }
                break;

        case CSR_MISSED:        /*  csr8  */
                break;

        case CSR_MIIROM:        /*  csr9  */
                if (writeflag == MEM_WRITE) {
                        if (idata & MIIROM_MDC)
                                mii_access(cpu, d, oldreg, idata);
                        else
                                srom_access(cpu, d, oldreg, idata);
                }
                break;

        case CSR_SIASTAT:       /*  csr12  */
                /*  Auto-negotiation status = Good.  */
                odata = SIASTAT_ANS_FLPGOOD;
                break;

        case CSR_SIATXRX:       /*  csr14  */
                /*  Auto-negotiation Enabled  */
                odata = SIATXRX_ANE;
                break;

        case CSR_SIACONN:       /*  csr13  */
        case CSR_SIAGEN:        /*  csr15  */
                /*  Don't print warnings for these, for now.  */
                break;

        default:if (writeflag == MEM_READ)
                        fatal("[ dec21143: read from unimplemented 0x%02x ]\n",
                            (int)relative_addr);
                else
                        fatal("[ dec21143: write to unimplemented 0x%02x: "
                            "0x%02x ]\n", (int)relative_addr, (int)idata);
        }

        if (writeflag == MEM_READ)
                memory_writemax64(cpu, data, len | d->pci_little_endian, odata);

        return 1;
}


DEVINIT(dec21143)
{
        struct dec21143_data *d;
        char name2[100];

        d = malloc(sizeof(struct dec21143_data));
        if (d == NULL) {
                fprintf(stderr, "out of memory\n");
                exit(1);
        }
        memset(d, 0, sizeof(struct dec21143_data));

        d->irq_nr = devinit->irq_nr;
        d->pci_little_endian = devinit->pci_little_endian;

        net_generate_unique_mac(devinit->machine, d->mac);
        net_add_nic(devinit->machine->emul->net, d, d->mac);
        d->net = devinit->machine->emul->net;

        dec21143_reset(devinit->machine->cpus[0], d);

        snprintf(name2, sizeof(name2), "%s [%02x:%02x:%02x:%02x:%02x:%02x]",
            devinit->name, d->mac[0], d->mac[1], d->mac[2], d->mac[3],
            d->mac[4], d->mac[5]);

        memory_device_register(devinit->machine->memory, name2,
            devinit->addr, 0x100, dev_dec21143_access, d, DM_DEFAULT, NULL);

        machine_add_tickfunction(devinit->machine,
            dev_dec21143_tick, d, DEC21143_TICK_SHIFT, 0.0);

        /*
         *  NetBSD/cats uses memory accesses, OpenBSD/cats uses I/O registers.
         *  Let's make a mirror from the memory range to the I/O range:
         */
        dev_ram_init(devinit->machine, devinit->addr2, 0x100, DEV_RAM_MIRROR
            | DEV_RAM_MIGHT_POINT_TO_DEVICES, devinit->addr);

        return 1;
}
