u-boot中网口处理--软件部分

u-boot中DM9000驱动分析

1. CSRs和PHY reg读写。

 static u16
 phy_read(int reg)
 {
     u16 val;

     /* Fill the phyxcer register into REG_0C */
     DM9000_iow(DM9000_EPAR, DM9000_PHY | reg);
     DM9000_iow(DM9000_EPCR, 0xc);    /* Issue phyxcer read command */
     udelay();        /* Wait read complete */
     DM9000_iow(DM9000_EPCR, 0x0);    /* Clear phyxcer read command */
     val = (DM9000_ior(DM9000_EPDRH) << ) | DM9000_ior(DM9000_EPDRL);

     /* The read data keeps on REG_0D & REG_0E */
     DM9000_DBG("phy_read(%d): %d\n", reg, val);
     return val;
 }

phy_read

 static void
 phy_write(int reg, u16 value)
 {

     /* Fill the phyxcer register into REG_0C */
     DM9000_iow(DM9000_EPAR, DM9000_PHY | reg);

     /* Fill the written data into REG_0D & REG_0E */
     DM9000_iow(DM9000_EPDRL, (value & 0xff));
     DM9000_iow(DM9000_EPDRH, ((value >> ) & 0xff));
     DM9000_iow(DM9000_EPCR, 0xa);    /* Issue phyxcer write command */
     udelay();        /* Wait write complete */
     DM9000_iow(DM9000_EPCR, 0x0);    /* Clear phyxcer write command */
     DM9000_DBG("phy_write(reg:%d, value:%d)\n", reg, value);
 }

phy_write

 static u8
 DM9000_ior(int reg)
 {
     u32     val;

     VALIDATE_ADDR_PORT(reg)

     val = *(u16*)DM9000_DATA;

     val &= 0xffff;

     return (u8)val;
 }

DM9000_ior

 static void
 DM9000_iow(int reg, u8 value)
 {
     VALIDATE_ADDR_PORT(reg)

     *(u16*)(DM9000_DATA) =     (u16)value;
 }

DM9000_iow

 #define    VALIDATE_ADDR_PORT(p) \
     if( m_uLastAddressPort != (p) ) \
         { \
             *(u16*)(DM9000_IO)  =(u16)(p);\
             m_uLastAddressPort = (p);\
         }

VALIDATE_ADDR_PORT

2. 网口收发

 int
 eth_rx(void)
 {
     u8 rxbyte, *rdptr = (u8 *) NetRxPackets[];
     int     errors=;
     u16        RxLen;

     u32     desc;
     PDM9000_RX_DESCRIPTOR    pdesc;

     DM9000_ior(DM9000_RSR);
     DM9000_ior(DM9000_ROCR);    

     for(pdesc=(PDM9000_RX_DESCRIPTOR)&desc;;)
     {
         // probe first byte
         desc = DeviceReadDataWithoutIncrement();
         DM9000_DBG("1:\tdesc is 0x%x\n",desc);

         // check if packet available, 01h means available, 00h means no data
         if(pdesc->bState != 0x01)
         {
             RxLen = ;
             break;
         }

         // get the data descriptor again
         desc = DeviceReadData();
         DM9000_DBG("2:\tdesc is 0x%x\n",desc);        

         DM9000_DBG("len is 0x%x\n",pdesc->nLength);                

         DeviceReadString(rdptr,pdesc->nLength);

         // check status, as specified in DM9000_RXSR,
         // the following bits are error
         // <3> PLE
         // <2> AE
         // <1> CE
         // <0> FOE
         if(pdesc->bStatus & MAKE_MASK4(,,,))
         {
             errors++;
             continue;
         } // of error happens

         RxLen =pdesc->nLength;

         break;
     } // of forever read loop

     /* Pass to upper layer */
     DM9000_DBG("passing packet to upper layer\n");
     NetReceive(NetRxPackets[], RxLen);
     return RxLen;
 }

eth_rx

 int
 eth_send(volatile void *packet, int length)
 {
     unsigned int loop;
 #if 0
     for(loop = ; loop<length;loop++)
     {
         printf("%02x ",*((char *)packet+loop));
     }
     printf("\n");
 #endif
     DeviceWriteString((u8*)packet,length);

     DM9000_iow(DM9000_TXPLH,HIGH_BYTE(length));
     DM9000_iow(DM9000_TXPLL,LOW_BYTE(length));

     // TXCR<0>, issue TX request
     DM9000_iow(DM9000_TCR, MAKE_MASK());

     DM9000_DBG("transmit done\n\n");
     return ;
 }

eth_send

数据接收时首先比对包头4个字节，第一个字节必须是0x01，第3，4字节是数据长度（减去开头的4个字节）。

接收完数据后再比对第二字节（DM9000 RSR），确认是否又错误发生。

用到的编程技巧是读取的包头4个字节直接赋值给一个u32，最低字节即为01，高两位为包长度。