FreeBSD/Linux Kernel Cross Reference
sys/pci/if_tlreg.h

     /*
      * Copyright (c) 1997, 1998
      *      Bill Paul <wpaul@ctr.columbia.edu>.  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. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by Bill Paul.
     * 4. Neither the name of the author nor the names of any co-contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY Bill Paul 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 Bill Paul OR THE VOICES IN HIS HEAD
     * 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.
     *
     * $FreeBSD: releng/5.0/sys/pci/if_tlreg.h 105599 2002-10-21 02:54:50Z brooks $
     */
    
    
    struct tl_type {
            u_int16_t               tl_vid;
            u_int16_t               tl_did;
            char                    *tl_name;
    };
    
    /*
     * ThunderLAN TX/RX list format. The TX and RX lists are pretty much
     * identical: the list begins with a 32-bit forward pointer which points
     * at the next list in the chain, followed by 16 bits for the total
     * frame size, and a 16 bit status field. This is followed by a series
     * of 10 32-bit data count/data address pairs that point to the fragments
     * that make up the complete frame.
     */
    
    #define TL_MAXFRAGS             10
    #define TL_RX_LIST_CNT          64
    #define TL_TX_LIST_CNT          128
    #define TL_MIN_FRAMELEN         64
    
    struct tl_frag {
            u_int32_t               tlist_dcnt;
            u_int32_t               tlist_dadr;
    };
    
    struct tl_list {
            u_int32_t               tlist_fptr;     /* phys address of next list */
            u_int16_t               tlist_cstat;    /* status word */
            u_int16_t               tlist_frsize;   /* size of data in frame */
            struct tl_frag          tl_frag[TL_MAXFRAGS];
    };
    
    /*
     * This is a special case of an RX list. By setting the One_Frag
     * bit in the NETCONFIG register, the driver can force the ThunderLAN
     * chip to use only one fragment when DMAing RX frames.
     */
    
    struct tl_list_onefrag {
            u_int32_t               tlist_fptr;
            u_int16_t               tlist_cstat;
            u_int16_t               tlist_frsize;
            struct tl_frag          tl_frag;
    };
    
    struct tl_list_data {
            struct tl_list_onefrag  tl_rx_list[TL_RX_LIST_CNT];
            struct tl_list          tl_tx_list[TL_TX_LIST_CNT];
            unsigned char           tl_pad[TL_MIN_FRAMELEN];
    };
    
    struct tl_chain {
            struct tl_list          *tl_ptr;
            struct mbuf             *tl_mbuf;
            struct tl_chain         *tl_next;
    };
    
    struct tl_chain_onefrag {
            struct tl_list_onefrag  *tl_ptr;
            struct mbuf             *tl_mbuf;
            struct tl_chain_onefrag *tl_next;
    };
    
    struct tl_chain_data {
           struct tl_chain_onefrag tl_rx_chain[TL_RX_LIST_CNT];
           struct tl_chain         tl_tx_chain[TL_TX_LIST_CNT];
   
           struct tl_chain_onefrag *tl_rx_head;
           struct tl_chain_onefrag *tl_rx_tail;
   
           struct tl_chain         *tl_tx_head;
           struct tl_chain         *tl_tx_tail;
           struct tl_chain         *tl_tx_free;
   };
   
   struct tl_softc {
           struct arpcom           arpcom;         /* interface info */
           struct ifmedia          ifmedia;        /* media info */
           bus_space_handle_t      tl_bhandle;
           bus_space_tag_t         tl_btag;
           void                    *tl_intrhand;
           struct resource         *tl_irq;
           struct resource         *tl_res;
           device_t                tl_miibus;
           struct tl_type          *tl_dinfo;      /* ThunderLAN adapter info */
           u_int8_t                tl_eeaddr;
           struct tl_list_data     *tl_ldata;      /* TX/RX lists and mbufs */
           struct tl_chain_data    tl_cdata;
           u_int8_t                tl_txeoc;
           u_int8_t                tl_bitrate;
           int                     tl_if_flags;
           struct callout_handle   tl_stat_ch;
           struct mtx              tl_mtx;
   };
   
   #define TL_LOCK(_sc)            mtx_lock(&(_sc)->tl_mtx)
   #define TL_UNLOCK(_sc)          mtx_unlock(&(_sc)->tl_mtx)
   
   /*
    * Transmit interrupt threshold.
    */
   #define TX_THR          0x00000004
   
   /*
    * General constants that are fun to know.
    *
    * The ThunderLAN controller is made by Texas Instruments. The
    * manual indicates that if the EEPROM checksum fails, the PCI
    * vendor and device ID registers will be loaded with TI-specific
    * values.
    */
   #define TI_VENDORID             0x104C
   #define TI_DEVICEID_THUNDERLAN  0x0500
   
   /*
    * These are the PCI vendor and device IDs for Compaq ethernet
    * adapters based on the ThunderLAN controller.
    */
   #define COMPAQ_VENDORID                         0x0E11
   #define COMPAQ_DEVICEID_NETEL_10_100            0xAE32
   #define COMPAQ_DEVICEID_NETEL_UNKNOWN           0xAE33
   #define COMPAQ_DEVICEID_NETEL_10                0xAE34
   #define COMPAQ_DEVICEID_NETFLEX_3P_INTEGRATED   0xAE35
   #define COMPAQ_DEVICEID_NETEL_10_100_DUAL       0xAE40
   #define COMPAQ_DEVICEID_NETEL_10_100_PROLIANT   0xAE43
   #define COMPAQ_DEVICEID_NETEL_10_100_EMBEDDED   0xB011
   #define COMPAQ_DEVICEID_NETEL_10_T2_UTP_COAX    0xB012
   #define COMPAQ_DEVICEID_NETEL_10_100_TX_UTP     0xB030
   #define COMPAQ_DEVICEID_NETFLEX_3P              0xF130
   #define COMPAQ_DEVICEID_NETFLEX_3P_BNC          0xF150
   
   /*
    * These are the PCI vendor and device IDs for Olicom
    * adapters based on the ThunderLAN controller.
    */
   #define OLICOM_VENDORID                         0x108D
   #define OLICOM_DEVICEID_OC2183                  0x0013
   #define OLICOM_DEVICEID_OC2325                  0x0012
   #define OLICOM_DEVICEID_OC2326                  0x0014
   
   /*
    * PCI low memory base and low I/O base
    */
   #define TL_PCI_LOIO             0x10
   #define TL_PCI_LOMEM            0x14
   
   /*
    * PCI latency timer (it's actually 0x0D, but we want a value
    * that's longword aligned).
    */
   #define TL_PCI_LATENCY_TIMER    0x0C
   
   #define TL_DIO_ADDR_INC         0x8000  /* Increment addr on each read */
   #define TL_DIO_RAM_SEL          0x4000  /* RAM address select */
   #define TL_DIO_ADDR_MASK        0x3FFF  /* address bits mask */
   
   /*
    * Interrupt types
    */
   #define TL_INTR_INVALID         0x0
   #define TL_INTR_TXEOF           0x1
   #define TL_INTR_STATOFLOW       0x2
   #define TL_INTR_RXEOF           0x3
   #define TL_INTR_DUMMY           0x4
   #define TL_INTR_TXEOC           0x5
   #define TL_INTR_ADCHK           0x6
   #define TL_INTR_RXEOC           0x7
   
   #define TL_INT_MASK             0x001C
   #define TL_VEC_MASK             0x1FE0
   /*
    * Host command register bits
    */
   #define TL_CMD_GO               0x80000000
   #define TL_CMD_STOP             0x40000000
   #define TL_CMD_ACK              0x20000000
   #define TL_CMD_CHSEL7           0x10000000
   #define TL_CMD_CHSEL6           0x08000000
   #define TL_CMD_CHSEL5           0x04000000
   #define TL_CMD_CHSEL4           0x02000000
   #define TL_CMD_CHSEL3           0x01000000
   #define TL_CMD_CHSEL2           0x00800000
   #define TL_CMD_CHSEL1           0x00400000
   #define TL_CMD_CHSEL0           0x00200000
   #define TL_CMD_EOC              0x00100000
   #define TL_CMD_RT               0x00080000
   #define TL_CMD_NES              0x00040000
   #define TL_CMD_ZERO0            0x00020000
   #define TL_CMD_ZERO1            0x00010000
   #define TL_CMD_ADRST            0x00008000
   #define TL_CMD_LDTMR            0x00004000
   #define TL_CMD_LDTHR            0x00002000
   #define TL_CMD_REQINT           0x00001000
   #define TL_CMD_INTSOFF          0x00000800
   #define TL_CMD_INTSON           0x00000400
   #define TL_CMD_RSVD0            0x00000200
   #define TL_CMD_RSVD1            0x00000100
   #define TL_CMD_ACK7             0x00000080
   #define TL_CMD_ACK6             0x00000040
   #define TL_CMD_ACK5             0x00000020
   #define TL_CMD_ACK4             0x00000010
   #define TL_CMD_ACK3             0x00000008
   #define TL_CMD_ACK2             0x00000004
   #define TL_CMD_ACK1             0x00000002
   #define TL_CMD_ACK0             0x00000001
   
   #define TL_CMD_CHSEL_MASK       0x01FE0000
   #define TL_CMD_ACK_MASK         0xFF
   
   /*
    * EEPROM address where station address resides.
    */
   #define TL_EEPROM_EADDR         0x83
   #define TL_EEPROM_EADDR2        0x99
   #define TL_EEPROM_EADDR3        0xAF
   #define TL_EEPROM_EADDR_OC      0xF8    /* Olicom cards use a different
                                              address than Compaqs. */
   /*
    * ThunderLAN host command register offsets.
    * (Can be accessed either by IO ports or memory map.)
    */
   #define TL_HOSTCMD              0x00
   #define TL_CH_PARM              0x04
   #define TL_DIO_ADDR             0x08
   #define TL_HOST_INT             0x0A
   #define TL_DIO_DATA             0x0C
   
   /*
    * ThunderLAN internal registers
    */
   #define TL_NETCMD               0x00
   #define TL_NETSIO               0x01
   #define TL_NETSTS               0x02
   #define TL_NETMASK              0x03
   
   #define TL_NETCONFIG            0x04
   #define TL_MANTEST              0x06
   
   #define TL_VENID_LSB            0x08
   #define TL_VENID_MSB            0x09
   #define TL_DEVID_LSB            0x0A
   #define TL_DEVID_MSB            0x0B
   
   #define TL_REVISION             0x0C
   #define TL_SUBCLASS             0x0D
   #define TL_MINLAT               0x0E
   #define TL_MAXLAT               0x0F
   
   #define TL_AREG0_B5             0x10
   #define TL_AREG0_B4             0x11
   #define TL_AREG0_B3             0x12
   #define TL_AREG0_B2             0x13
   
   #define TL_AREG0_B1             0x14
   #define TL_AREG0_B0             0x15
   #define TL_AREG1_B5             0x16
   #define TL_AREG1_B4             0x17
   
   #define TL_AREG1_B3             0x18
   #define TL_AREG1_B2             0x19
   #define TL_AREG1_B1             0x1A
   #define TL_AREG1_B0             0x1B
   
   #define TL_AREG2_B5             0x1C
   #define TL_AREG2_B4             0x1D
   #define TL_AREG2_B3             0x1E
   #define TL_AREG2_B2             0x1F
   
   #define TL_AREG2_B1             0x20
   #define TL_AREG2_B0             0x21
   #define TL_AREG3_B5             0x22
   #define TL_AREG3_B4             0x23
   
   #define TL_AREG3_B3             0x24
   #define TL_AREG3_B2             0x25
   #define TL_AREG3_B1             0x26
   #define TL_AREG3_B0             0x27
   
   #define TL_HASH1                0x28
   #define TL_HASH2                0x2C
   #define TL_TXGOODFRAMES         0x30
   #define TL_TXUNDERRUN           0x33
   #define TL_RXGOODFRAMES         0x34
   #define TL_RXOVERRUN            0x37
   #define TL_DEFEREDTX            0x38
   #define TL_CRCERROR             0x3A
   #define TL_CODEERROR            0x3B
   #define TL_MULTICOLTX           0x3C
   #define TL_SINGLECOLTX          0x3E
   #define TL_EXCESSIVECOL         0x40
   #define TL_LATECOL              0x41
   #define TL_CARRIERLOSS          0x42
   #define TL_ACOMMIT              0x43
   #define TL_LDREG                0x44
   #define TL_BSIZEREG             0x45
   #define TL_MAXRX                0x46
   
   /*
    * ThunderLAN SIO register bits
    */
   #define TL_SIO_MINTEN           0x80
   #define TL_SIO_ECLOK            0x40
   #define TL_SIO_ETXEN            0x20
   #define TL_SIO_EDATA            0x10
   #define TL_SIO_NMRST            0x08
   #define TL_SIO_MCLK             0x04
   #define TL_SIO_MTXEN            0x02
   #define TL_SIO_MDATA            0x01
   
   /*
    * Thunderlan NETCONFIG bits
    */
   #define TL_CFG_RCLKTEST         0x8000
   #define TL_CFG_TCLKTEST         0x4000
   #define TL_CFG_BITRATE          0x2000
   #define TL_CFG_RXCRC            0x1000
   #define TL_CFG_PEF              0x0800
   #define TL_CFG_ONEFRAG          0x0400
   #define TL_CFG_ONECHAN          0x0200
   #define TL_CFG_MTEST            0x0100
   #define TL_CFG_PHYEN            0x0080
   #define TL_CFG_MACSEL6          0x0040
   #define TL_CFG_MACSEL5          0x0020
   #define TL_CFG_MACSEL4          0x0010
   #define TL_CFG_MACSEL3          0x0008
   #define TL_CFG_MACSEL2          0x0004
   #define TL_CFG_MACSEL1          0x0002
   #define TL_CFG_MACSEL0          0x0001
   
   /*
    * ThunderLAN NETSTS bits
    */
   #define TL_STS_MIRQ             0x80
   #define TL_STS_HBEAT            0x40
   #define TL_STS_TXSTOP           0x20
   #define TL_STS_RXSTOP           0x10
   
   /*
    * ThunderLAN NETCMD bits
    */
   #define TL_CMD_NRESET           0x80
   #define TL_CMD_NWRAP            0x40
   #define TL_CMD_CSF              0x20
   #define TL_CMD_CAF              0x10
   #define TL_CMD_NOBRX            0x08
   #define TL_CMD_DUPLEX           0x04
   #define TL_CMD_TRFRAM           0x02
   #define TL_CMD_TXPACE           0x01
   
   /*
    * ThunderLAN NETMASK bits
    */
   #define TL_MASK_MASK7           0x80
   #define TL_MASK_MASK6           0x40
   #define TL_MASK_MASK5           0x20
   #define TL_MASK_MASK4           0x10
   
   /*
    * MII frame format
    */
   #ifdef ANSI_DOESNT_ALLOW_BITFIELDS
   struct tl_mii_frame {
           u_int16_t               mii_stdelim:2,
                                   mii_opcode:2,
                                   mii_phyaddr:5,
                                   mii_regaddr:5,
                                   mii_turnaround:2;
           u_int16_t               mii_data;
   };
   #else
   struct tl_mii_frame {
           u_int8_t                mii_stdelim;
           u_int8_t                mii_opcode;
           u_int8_t                mii_phyaddr;
           u_int8_t                mii_regaddr;
           u_int8_t                mii_turnaround;
           u_int16_t               mii_data;
   };
   #endif
   /*
    * MII constants
    */
   #define TL_MII_STARTDELIM       0x01
   #define TL_MII_READOP           0x02
   #define TL_MII_WRITEOP          0x01
   #define TL_MII_TURNAROUND       0x02
   
   #define TL_LAST_FRAG            0x80000000
   #define TL_CSTAT_UNUSED         0x8000
   #define TL_CSTAT_FRAMECMP       0x4000
   #define TL_CSTAT_READY          0x3000
   #define TL_CSTAT_UNUSED13       0x2000
   #define TL_CSTAT_UNUSED12       0x1000
   #define TL_CSTAT_EOC            0x0800
   #define TL_CSTAT_RXERROR        0x0400
   #define TL_CSTAT_PASSCRC        0x0200
   #define TL_CSTAT_DPRIO          0x0100
   
   #define TL_FRAME_MASK           0x00FFFFFF
   #define tl_tx_goodframes(x)     (x.tl_txstat & TL_FRAME_MASK)
   #define tl_tx_underrun(x)       ((x.tl_txstat & ~TL_FRAME_MASK) >> 24)
   #define tl_rx_goodframes(x)     (x.tl_rxstat & TL_FRAME_MASK)
   #define tl_rx_overrun(x)        ((x.tl_rxstat & ~TL_FRAME_MASK) >> 24)
   
   struct tl_stats {
           u_int32_t               tl_txstat;
           u_int32_t               tl_rxstat;
           u_int16_t               tl_deferred;
           u_int8_t                tl_crc_errors;
           u_int8_t                tl_code_errors;
           u_int16_t               tl_tx_multi_collision;
           u_int16_t               tl_tx_single_collision;
           u_int8_t                tl_excessive_collision;
           u_int8_t                tl_late_collision;
           u_int8_t                tl_carrier_loss;
           u_int8_t                acommit;
   };
   
   /*
    * ACOMMIT register bits. These are used only when a bitrate
    * PHY is selected ('bitrate' bit in netconfig register is set).
    */
   #define TL_AC_MTXER             0x01    /* reserved */
   #define TL_AC_MTXD1             0x02    /* 0 == 10baseT 1 == AUI */
   #define TL_AC_MTXD2             0x04    /* loopback disable */
   #define TL_AC_MTXD3             0x08    /* full duplex disable */
   
   #define TL_AC_TXTHRESH          0xF0
   #define TL_AC_TXTHRESH_16LONG   0x00
   #define TL_AC_TXTHRESH_32LONG   0x10
   #define TL_AC_TXTHRESH_64LONG   0x20
   #define TL_AC_TXTHRESH_128LONG  0x30
   #define TL_AC_TXTHRESH_256LONG  0x40
   #define TL_AC_TXTHRESH_WHOLEPKT 0x50
   
   /*
    * PCI burst size register (TL_BSIZEREG).
    */
   #define TL_RXBURST              0x0F
   #define TL_TXBURST              0xF0
   
   #define TL_RXBURST_4LONG        0x00
   #define TL_RXBURST_8LONG        0x01
   #define TL_RXBURST_16LONG       0x02
   #define TL_RXBURST_32LONG       0x03
   #define TL_RXBURST_64LONG       0x04
   #define TL_RXBURST_128LONG      0x05
   
   #define TL_TXBURST_4LONG        0x00
   #define TL_TXBURST_8LONG        0x10
   #define TL_TXBURST_16LONG       0x20
   #define TL_TXBURST_32LONG       0x30
   #define TL_TXBURST_64LONG       0x40
   #define TL_TXBURST_128LONG      0x50
   
   /*
    * register space access macros
    */
   #define CSR_WRITE_4(sc, reg, val)       \
           bus_space_write_4(sc->tl_btag, sc->tl_bhandle, reg, val)
   #define CSR_WRITE_2(sc, reg, val)       \
           bus_space_write_2(sc->tl_btag, sc->tl_bhandle, reg, val)
   #define CSR_WRITE_1(sc, reg, val)       \
           bus_space_write_1(sc->tl_btag, sc->tl_bhandle, reg, val)
   
   #define CSR_READ_4(sc, reg)             \
           bus_space_read_4(sc->tl_btag, sc->tl_bhandle, reg)
   #define CSR_READ_2(sc, reg)             \
           bus_space_read_2(sc->tl_btag, sc->tl_bhandle, reg)
   #define CSR_READ_1(sc, reg)             \
           bus_space_read_1(sc->tl_btag, sc->tl_bhandle, reg)
   
   #define CMD_PUT(sc, x) CSR_WRITE_4(sc, TL_HOSTCMD, x)
   #define CMD_SET(sc, x)  \
           CSR_WRITE_4(sc, TL_HOSTCMD, CSR_READ_4(sc, TL_HOSTCMD) | (x))
   #define CMD_CLR(sc, x)  \
           CSR_WRITE_4(sc, TL_HOSTCMD, CSR_READ_4(sc, TL_HOSTCMD) & ~(x))
   
   /*
    * ThunderLAN adapters typically have a serial EEPROM containing
    * configuration information. The main reason we're interested in
    * it is because it also contains the adapters's station address.
    *
    * Access to the EEPROM is a bit goofy since it is a serial device:
    * you have to do reads and writes one bit at a time. The state of
    * the DATA bit can only change while the CLOCK line is held low.
    * Transactions work basically like this:
    *
    * 1) Send the EEPROM_START sequence to prepare the EEPROM for
    *    accepting commands. This pulls the clock high, sets
    *    the data bit to 0, enables transmission to the EEPROM,
    *    pulls the data bit up to 1, then pulls the clock low.
    *    The idea is to do a 0 to 1 transition of the data bit
    *    while the clock pin is held high.
    *
    * 2) To write a bit to the EEPROM, set the TXENABLE bit, then
    *    set the EDATA bit to send a 1 or clear it to send a 0.
    *    Finally, set and then clear ECLOK. Strobing the clock
    *    transmits the bit. After 8 bits have been written, the
    *    EEPROM should respond with an ACK, which should be read.
    *
    * 3) To read a bit from the EEPROM, clear the TXENABLE bit,
    *    then set ECLOK. The bit can then be read by reading EDATA.
    *    ECLOCK should then be cleared again. This can be repeated
    *    8 times to read a whole byte, after which the 
    *
    * 4) We need to send the address byte to the EEPROM. For this
    *    we have to send the write control byte to the EEPROM to
    *    tell it to accept data. The byte is 0xA0. The EEPROM should
    *    ack this. The address byte can be send after that.
    *
    * 5) Now we have to tell the EEPROM to send us data. For that we
    *    have to transmit the read control byte, which is 0xA1. This
    *    byte should also be acked. We can then read the data bits
    *    from the EEPROM.
    *
    * 6) When we're all finished, send the EEPROM_STOP sequence.
    *
    * Note that we use the ThunderLAN's NetSio register to access the
    * EEPROM, however there is an alternate method. There is a PCI NVRAM
    * register at PCI offset 0xB4 which can also be used with minor changes.
    * The difference is that access to PCI registers via pci_conf_read()
    * and pci_conf_write() is done using programmed I/O, which we want to
    * avoid.
    */
   
   /*
    * Note that EEPROM_START leaves transmission enabled.
    */
   #define EEPROM_START                                                    \
           tl_dio_setbit(sc, TL_NETSIO, TL_SIO_ECLOK); /* Pull clock pin high */\
           tl_dio_setbit(sc, TL_NETSIO, TL_SIO_EDATA); /* Set DATA bit to 1 */     \
           tl_dio_setbit(sc, TL_NETSIO, TL_SIO_ETXEN); /* Enable xmit to write bit */\
           tl_dio_clrbit(sc, TL_NETSIO, TL_SIO_EDATA); /* Pull DATA bit to 0 again */\
           tl_dio_clrbit(sc, TL_NETSIO, TL_SIO_ECLOK); /* Pull clock low again */
   
   /*
    * EEPROM_STOP ends access to the EEPROM and clears the ETXEN bit so
    * that no further data can be written to the EEPROM I/O pin.
    */
   #define EEPROM_STOP                                                     \
           tl_dio_clrbit(sc, TL_NETSIO, TL_SIO_ETXEN); /* Disable xmit */  \
           tl_dio_clrbit(sc, TL_NETSIO, TL_SIO_EDATA); /* Pull DATA to 0 */        \
           tl_dio_setbit(sc, TL_NETSIO, TL_SIO_ECLOK); /* Pull clock high */       \
           tl_dio_setbit(sc, TL_NETSIO, TL_SIO_ETXEN); /* Enable xmit */   \
           tl_dio_setbit(sc, TL_NETSIO, TL_SIO_EDATA); /* Toggle DATA to 1 */      \
           tl_dio_clrbit(sc, TL_NETSIO, TL_SIO_ETXEN); /* Disable xmit. */ \
           tl_dio_clrbit(sc, TL_NETSIO, TL_SIO_ECLOK); /* Pull clock low again */
   
   
   /*
    * Microchip Technology 24Cxx EEPROM control bytes
    */
   #define EEPROM_CTL_READ                 0xA1    /* 0101 0001 */
   #define EEPROM_CTL_WRITE                0xA0    /* 0101 0000 */
   
   #ifdef __alpha__
   #undef vtophys
   #define vtophys(va)             alpha_XXX_dmamap((vm_offset_t)va)
   #endif

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