nuc472_eth_driver.c

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/**
 * @file nuc472_eth_driver.c
 * @brief Nuvoton NUC472 Ethernet MAC driver
 *
 * @section License
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 *
 * Copyright (C) 2010-2024 Oryx Embedded SARL. All rights reserved.
 *
 * This file is part of CycloneTCP Open.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * @author Oryx Embedded SARL (www.oryx-embedded.com)
 * @version 2.4.4
 **/
 
//Switch to the appropriate trace level
#define TRACE_LEVEL NIC_TRACE_LEVEL
 
//Dependencies
#include "nuc472_442.h"
#include "core/net.h"
#include "drivers/mac/nuc472_eth_driver.h"
#include "debug.h"
 
//Underlying network interface
static NetInterface *nicDriverInterface;
 
//IAR EWARM compiler?
#if defined(__ICCARM__)
 
//Transmit buffer
#pragma data_alignment = 4
static uint8_t txBuffer[NUC472_ETH_TX_BUFFER_COUNT][NUC472_ETH_TX_BUFFER_SIZE];
//Receive buffer
#pragma data_alignment = 4
static uint8_t rxBuffer[NUC472_ETH_RX_BUFFER_COUNT][NUC472_ETH_RX_BUFFER_SIZE];
//Transmit DMA descriptors
#pragma data_alignment = 4
static Nuc472TxDmaDesc txDmaDesc[NUC472_ETH_TX_BUFFER_COUNT];
//Receive DMA descriptors
#pragma data_alignment = 4
static Nuc472RxDmaDesc rxDmaDesc[NUC472_ETH_RX_BUFFER_COUNT];
 
//Keil MDK-ARM or GCC compiler?
#else
 
//Transmit buffer
static uint8_t txBuffer[NUC472_ETH_TX_BUFFER_COUNT][NUC472_ETH_TX_BUFFER_SIZE]
   __attribute__((aligned(4)));
//Receive buffer
static uint8_t rxBuffer[NUC472_ETH_RX_BUFFER_COUNT][NUC472_ETH_RX_BUFFER_SIZE]
   __attribute__((aligned(4)));
//Transmit DMA descriptors
static Nuc472TxDmaDesc txDmaDesc[NUC472_ETH_TX_BUFFER_COUNT]
   __attribute__((aligned(4)));
//Receive DMA descriptors
static Nuc472RxDmaDesc rxDmaDesc[NUC472_ETH_RX_BUFFER_COUNT]
   __attribute__((aligned(4)));
 
#endif
 
//Current transmit descriptor
static uint_t txIndex;
//Current receive descriptor
static uint_t rxIndex;
 
 
/**
 * @brief NUC472 Ethernet MAC driver
 **/
 
const NicDriver nuc472EthDriver =
{
   NIC_TYPE_ETHERNET,
   ETH_MTU,
   nuc472EthInit,
   nuc472EthTick,
   nuc472EthEnableIrq,
   nuc472EthDisableIrq,
   nuc472EthEventHandler,
   nuc472EthSendPacket,
   nuc472EthUpdateMacAddrFilter,
   nuc472EthUpdateMacConfig,
   nuc472EthWritePhyReg,
   nuc472EthReadPhyReg,
   TRUE,
   TRUE,
   TRUE,
   FALSE
};
 
 
/**
 * @brief NUC472 Ethernet MAC initialization
 * @param[in] interface Underlying network interface
 * @return Error code
 **/
 
error_t nuc472EthInit(NetInterface *interface)
{
   error_t error;
 
   //Debug message
   TRACE_INFO("Initializing NUC472 Ethernet MAC...\r\n");
 
   //Save underlying network interface
   nicDriverInterface = interface;
 
   //Enable EMAC clock
   CLK_EnableModuleClock(EMAC_MODULE);
   //Select MDC clock frequency
   CLK_SetModuleClock(EMAC_MODULE, 0, CLK_CLKDIV3_EMAC(100));
 
   //Perform a software reset
   EMAC->CTL |= EMAC_CTL_RST_Msk;
   //Wait for the reset to complete
   while((EMAC->CTL & EMAC_CTL_RST_Msk) != 0)
   {
   }
 
   //GPIO configuration
   nuc472EthInitGpio(interface);
 
   //Valid Ethernet PHY or switch driver?
   if(interface->phyDriver != NULL)
   {
      //Ethernet PHY initialization
      error = interface->phyDriver->init(interface);
   }
   else if(interface->switchDriver != NULL)
   {
      //Ethernet switch initialization
      error = interface->switchDriver->init(interface);
   }
   else
   {
      //The interface is not properly configured
      error = ERROR_FAILURE;
   }
 
   //Any error to report?
   if(error)
   {
      return error;
   }
 
   //Set the upper 32 bits of the MAC address
   EMAC->CAM0M = interface->macAddr.b[3] |
      (interface->macAddr.b[2] << 8) |
      (interface->macAddr.b[1] << 16) |
      (interface->macAddr.b[0] << 24);
 
   //Set the lower 16 bits of the MAC address
   EMAC->CAM0L = (interface->macAddr.b[5] << 16) |
      (interface->macAddr.b[4] << 24);
 
   //Enable the corresponding CAM entry
   EMAC->CAMEN = EMAC_CAMEN_CAMxEN_Msk << 0;
   //Accept broadcast and multicast packets
   EMAC->CAMCTL = EMAC_CAMCTL_CMPEN_Msk | EMAC_CAMCTL_ABP_Msk;
 
   //Maximum frame length that can be accepted
   EMAC->MRFL = NUC472_ETH_RX_BUFFER_SIZE;
 
   //Initialize DMA descriptor lists
   nuc472EthInitDmaDesc(interface);
 
   //Enable the desired MAC interrupts
   EMAC->INTEN = EMAC_INTEN_TXCPIEN_Msk | EMAC_INTEN_TXIEN_Msk |
      EMAC_INTEN_RXGDIEN_Msk | EMAC_INTEN_RXIEN_Msk;
 
   //Set priority grouping (4 bits for pre-emption priority, no bits for subpriority)
   NVIC_SetPriorityGrouping(NUC472_ETH_IRQ_PRIORITY_GROUPING);
 
   //Configure EMAC transmit interrupt priority
   NVIC_SetPriority(EMAC_TX_IRQn, NVIC_EncodePriority(NUC472_ETH_IRQ_PRIORITY_GROUPING,
      NUC472_ETH_IRQ_GROUP_PRIORITY, NUC472_ETH_IRQ_SUB_PRIORITY));
 
   //Configure EMAC receive interrupt priority
   NVIC_SetPriority(EMAC_RX_IRQn, NVIC_EncodePriority(NUC472_ETH_IRQ_PRIORITY_GROUPING,
      NUC472_ETH_IRQ_GROUP_PRIORITY, NUC472_ETH_IRQ_SUB_PRIORITY));
 
   //Enable transmission and reception
   EMAC->CTL |= EMAC_CTL_TXON_Msk | EMAC_CTL_RXON_Msk;
 
   //Accept any packets from the upper layer
   osSetEvent(&interface->nicTxEvent);
 
   //Successful initialization
   return NO_ERROR;
}
 
 
/**
 * @brief GPIO configuration
 * @param[in] interface Underlying network interface
 **/
 
__weak_func void nuc472EthInitGpio(NetInterface *interface)
{
//NuTiny-SDK-NUC472 or NuMaker-PFM-NUC472 evaluation board?
#if defined(USE_NUTINY_SDK_NUC472) || defined(USE_NUMAKER_PFM_NUC472)
   uint32_t temp;
 
   //Select RMII interface mode
   EMAC->CTL |= EMAC_CTL_RMIIEN_Msk | EMAC_CTL_RMIIRXCTL_Msk;
 
   //Configure EMAC_MII_MDC (PB.14) and EMAC_MII_MDIO (PB.15)
   temp = SYS->GPB_MFPH;
   temp = (temp & ~SYS_GPB_MFPH_PB14MFP_Msk) | SYS_GPB_MFPH_PB14MFP_EMAC_MII_MDC;
   temp = (temp & ~SYS_GPB_MFPH_PB15MFP_Msk) | SYS_GPB_MFPH_PB15MFP_EMAC_MII_MDIO;
   SYS->GPB_MFPH = temp;
 
   //Configure EMAC_REFCLK (PC.0), EMAC_MII_RXERR (PC.1), EMAC_MII_RXDV (PC.2),
   //EMAC_MII_RXD1 (PC.3), EMAC_MII_RXD0 (PC.4), EMAC_MII_TXD0 (PC.6) and
   //EMAC_MII_TXD1 (PC.7)
   temp = SYS->GPC_MFPL;
   temp = (temp & ~SYS_GPC_MFPL_PC0MFP_Msk) | SYS_GPC_MFPL_PC0MFP_EMAC_REFCLK;
   temp = (temp & ~SYS_GPC_MFPL_PC1MFP_Msk) | SYS_GPC_MFPL_PC1MFP_EMAC_MII_RXERR;
   temp = (temp & ~SYS_GPC_MFPL_PC2MFP_Msk) | SYS_GPC_MFPL_PC2MFP_EMAC_MII_RXDV;
   temp = (temp & ~SYS_GPC_MFPL_PC3MFP_Msk) | SYS_GPC_MFPL_PC3MFP_EMAC_MII_RXD1;
   temp = (temp & ~SYS_GPC_MFPL_PC4MFP_Msk) | SYS_GPC_MFPL_PC4MFP_EMAC_MII_RXD0;
   temp = (temp & ~SYS_GPC_MFPL_PC6MFP_Msk) | SYS_GPC_MFPL_PC6MFP_EMAC_MII_TXD0;
   temp = (temp & ~SYS_GPC_MFPL_PC7MFP_Msk) | SYS_GPC_MFPL_PC7MFP_EMAC_MII_TXD1;
   SYS->GPC_MFPL = temp;
 
   //Configure EMAC_MII_TXEN (PC.8)
   temp = SYS->GPC_MFPH;
   temp = (temp & ~SYS_GPC_MFPH_PC8MFP_Msk) | SYS_GPC_MFPH_PC8MFP_EMAC_MII_TXEN;
   SYS->GPC_MFPH = temp;
 
   //Enable high slew rate on RMII output pins
   PC->SLEWCTL |= GPIO_SLEWCTL_HSREN6_Msk | GPIO_SLEWCTL_HSREN7_Msk |
      GPIO_SLEWCTL_HSREN8_Msk;
#endif
}
 
 
/**
 * @brief Initialize DMA descriptor lists
 * @param[in] interface Underlying network interface
 **/
 
void nuc472EthInitDmaDesc(NetInterface *interface)
{
   uint_t i;
 
   //Initialize TX DMA descriptor list
   for(i = 0; i < NUC472_ETH_TX_BUFFER_COUNT; i++)
   {
      //The descriptor is initially owned by the CPU
      txDmaDesc[i].txdes0 = 0;
      //Transmit buffer address
      txDmaDesc[i].txdes1 = (uint32_t) txBuffer[i];
      //Transmit frame status
      txDmaDesc[i].txdes2 = 0;
      //Next descriptor address
      txDmaDesc[i].txdes3 = (uint32_t) &txDmaDesc[i + 1];
   }
 
   //The last descriptor is chained to the first entry
   txDmaDesc[i - 1].txdes3 = (uint32_t) &txDmaDesc[0];
   //Initialize TX descriptor index
   txIndex = 0;
 
   //Initialize RX DMA descriptor list
   for(i = 0; i < NUC472_ETH_RX_BUFFER_COUNT; i++)
   {
      //The descriptor is initially owned by the DMA
      rxDmaDesc[i].rxdes0 = EMAC_RXDES0_OWNER;
      //Receive buffer address
      rxDmaDesc[i].rxdes1 = (uint32_t) rxBuffer[i];
      //Reserved field
      rxDmaDesc[i].rxdes2 = 0;
      //Next descriptor address
      rxDmaDesc[i].rxdes3 = (uint32_t) &rxDmaDesc[i + 1];
   }
 
   //The last descriptor is chained to the first entry
   rxDmaDesc[i - 1].rxdes3 = (uint32_t) &rxDmaDesc[0];
   //Initialize RX descriptor index
   rxIndex = 0;
 
   //Start address of the TX descriptor list
   EMAC->TXDSA = (uint32_t) txDmaDesc;
   //Start address of the RX descriptor list
   EMAC->RXDSA = (uint32_t) rxDmaDesc;
}
 
 
/**
 * @brief NUC472 Ethernet MAC timer handler
 *
 * This routine is periodically called by the TCP/IP stack to handle periodic
 * operations such as polling the link state
 *
 * @param[in] interface Underlying network interface
 **/
 
void nuc472EthTick(NetInterface *interface)
{
   //Valid Ethernet PHY or switch driver?
   if(interface->phyDriver != NULL)
   {
      //Handle periodic operations
      interface->phyDriver->tick(interface);
   }
   else if(interface->switchDriver != NULL)
   {
      //Handle periodic operations
      interface->switchDriver->tick(interface);
   }
   else
   {
      //Just for sanity
   }
}
 
 
/**
 * @brief Enable interrupts
 * @param[in] interface Underlying network interface
 **/
 
void nuc472EthEnableIrq(NetInterface *interface)
{
   //Enable Ethernet MAC interrupts
   NVIC_EnableIRQ(EMAC_TX_IRQn);
   NVIC_EnableIRQ(EMAC_RX_IRQn);
 
   //Valid Ethernet PHY or switch driver?
   if(interface->phyDriver != NULL)
   {
      //Enable Ethernet PHY interrupts
      interface->phyDriver->enableIrq(interface);
   }
   else if(interface->switchDriver != NULL)
   {
      //Enable Ethernet switch interrupts
      interface->switchDriver->enableIrq(interface);
   }
   else
   {
      //Just for sanity
   }
}
 
 
/**
 * @brief Disable interrupts
 * @param[in] interface Underlying network interface
 **/
 
void nuc472EthDisableIrq(NetInterface *interface)
{
   //Disable Ethernet MAC interrupts
   NVIC_DisableIRQ(EMAC_TX_IRQn);
   NVIC_DisableIRQ(EMAC_RX_IRQn);
 
   //Valid Ethernet PHY or switch driver?
   if(interface->phyDriver != NULL)
   {
      //Disable Ethernet PHY interrupts
      interface->phyDriver->disableIrq(interface);
   }
   else if(interface->switchDriver != NULL)
   {
      //Disable Ethernet switch interrupts
      interface->switchDriver->disableIrq(interface);
   }
   else
   {
      //Just for sanity
   }
}
 
 
/**
 * @brief Ethernet MAC transmit interrupt
 **/
 
void EMAC_TX_IRQHandler(void)
{
   bool_t flag;
 
   //Interrupt service routine prologue
   osEnterIsr();
 
   //This flag will be set if a higher priority task must be woken
   flag = FALSE;
 
   //Packet transmitted?
   if((EMAC->INTSTS & EMAC_INTSTS_TXCPIF_Msk) != 0)
   {
      //Clear TXCPIF interrupt flag
      EMAC->INTSTS = EMAC_INTSTS_TXCPIF_Msk;
 
      //Check whether the TX buffer is available for writing
      if((txDmaDesc[txIndex].txdes0 & EMAC_TXDES0_OWNER) == 0)
      {
         //Notify the TCP/IP stack that the transmitter is ready to send
         flag |= osSetEventFromIsr(&nicDriverInterface->nicTxEvent);
      }
   }
 
   //Interrupt service routine epilogue
   osExitIsr(flag);
}
 
 
/**
 * @brief Ethernet MAC receive interrupt
 **/
 
void EMAC_RX_IRQHandler(void)
{
   bool_t flag;
 
   //Interrupt service routine prologue
   osEnterIsr();
 
   //This flag will be set if a higher priority task must be woken
   flag = FALSE;
 
   //Packet received?
   if((EMAC->INTSTS & EMAC_INTSTS_RXGDIF_Msk) != 0)
   {
      //Clear RXGDIF interrupt flag
      EMAC->INTSTS = EMAC_INTSTS_RXGDIF_Msk;
 
      //Set event flag
      nicDriverInterface->nicEvent = TRUE;
      //Notify the TCP/IP stack of the event
      flag |= osSetEventFromIsr(&netEvent);
   }
 
   //Interrupt service routine epilogue
   osExitIsr(flag);
}
 
 
/**
 * @brief NUC472 Ethernet MAC event handler
 * @param[in] interface Underlying network interface
 **/
 
void nuc472EthEventHandler(NetInterface *interface)
{
   error_t error;
 
   //Process all pending packets
   do
   {
      //Read incoming packet
      error = nuc472EthReceivePacket(interface);
 
      //No more data in the receive buffer?
   } while(error != ERROR_BUFFER_EMPTY);
}
 
 
/**
 * @brief Send a packet
 * @param[in] interface Underlying network interface
 * @param[in] buffer Multi-part buffer containing the data to send
 * @param[in] offset Offset to the first data byte
 * @param[in] ancillary Additional options passed to the stack along with
 *   the packet
 * @return Error code
 **/
 
error_t nuc472EthSendPacket(NetInterface *interface,
   const NetBuffer *buffer, size_t offset, NetTxAncillary *ancillary)
{
   size_t length;
   uint_t txNextIndex;
 
   //Retrieve the length of the packet
   length = netBufferGetLength(buffer) - offset;
 
   //Check the frame length
   if(length > NUC472_ETH_TX_BUFFER_SIZE)
   {
      //The transmitter can accept another packet
      osSetEvent(&interface->nicTxEvent);
      //Report an error
      return ERROR_INVALID_LENGTH;
   }
 
   //Make sure the current buffer is available for writing
   if((txDmaDesc[txIndex].txdes0 & EMAC_TXDES0_OWNER) != 0)
   {
      return ERROR_FAILURE;
   }
 
   //Copy user data to the transmit buffer
   netBufferRead((uint8_t *) txBuffer[txIndex], buffer, offset, length);
 
   //Calculate the index of the next descriptor
   txNextIndex = txIndex + 1;
 
   //Wrap around if necessary
   if(txNextIndex >= NUC472_ETH_TX_BUFFER_COUNT)
   {
      txNextIndex = 0;
   }
 
   //Set the start address of the buffer
   txDmaDesc[txIndex].txdes1 = (uint32_t) txBuffer[txIndex];
   //Write the number of bytes to send
   txDmaDesc[txIndex].txdes2 = length & EMAC_TXDES2_TBC;
   //Set the address of the next descriptor
   txDmaDesc[txIndex].txdes3 = (uint32_t) &txDmaDesc[txNextIndex];
 
   //Give the ownership of the descriptor to the DMA
   txDmaDesc[txIndex].txdes0 = EMAC_TXDES0_OWNER | EMAC_TXDES0_INTEN |
      EMAC_TXDES0_CRCAPP | EMAC_TXDES0_PADEN;
 
   //Instruct the DMA to poll the transmit descriptor list
   EMAC->TXST = 0;
 
   //Point to the next register
   txIndex = txNextIndex;
 
   //Check whether the next buffer is available for writing
   if((txDmaDesc[txIndex].txdes0 & EMAC_TXDES0_OWNER) == 0)
   {
      //The transmitter can accept another packet
      osSetEvent(&interface->nicTxEvent);
   }
 
   //Data successfully written
   return NO_ERROR;
}
 
 
/**
 * @brief Receive a packet
 * @param[in] interface Underlying network interface
 * @return Error code
 **/
 
error_t nuc472EthReceivePacket(NetInterface *interface)
{
   error_t error;
   size_t n;
   uint_t rxNextIndex;
   NetRxAncillary ancillary;
 
   //Current buffer available for reading?
   if((rxDmaDesc[rxIndex].rxdes0 & EMAC_RXDES0_OWNER) == 0)
   {
      //Valid frame received?
      if((rxDmaDesc[rxIndex].rxdes0 & EMAC_RXDES0_RXGDIF) != 0)
      {
         //Retrieve the length of the frame
         n = rxDmaDesc[rxIndex].rxdes0 & EMAC_RXDES0_RBC;
         //Limit the number of data to read
         n = MIN(n, NUC472_ETH_RX_BUFFER_SIZE);
 
         //Additional options can be passed to the stack along with the packet
         ancillary = NET_DEFAULT_RX_ANCILLARY;
 
         //Pass the packet to the upper layer
         nicProcessPacket(interface, rxBuffer[rxIndex], n, &ancillary);
 
         //Valid packet received
         error = NO_ERROR;
      }
      else
      {
         //The packet is not valid
         error = ERROR_INVALID_PACKET;
      }
 
      //Calculate the index of the next descriptor
      rxNextIndex = rxIndex + 1;
 
      //Wrap around if necessary
      if(rxNextIndex >= NUC472_ETH_RX_BUFFER_COUNT)
      {
         rxNextIndex = 0;
      }
 
      //Set the start address of the buffer
      rxDmaDesc[rxIndex].rxdes1 = (uint32_t) rxBuffer[rxIndex];
      //Set the address of the next descriptor
      rxDmaDesc[rxIndex].rxdes3 = (uint32_t) &rxDmaDesc[rxNextIndex];
      //Give the ownership of the descriptor back to the DMA
      rxDmaDesc[rxIndex].rxdes0 = EMAC_RXDES0_OWNER;
 
      //Point to the next register
      rxIndex = rxNextIndex;
   }
   else
   {
      //No more data in the receive buffer
      error = ERROR_BUFFER_EMPTY;
   }
 
   //Instruct the DMA to poll the receive descriptor list
   EMAC->RXST = 0;
 
   //Return status code
   return error;
}
 
 
/**
 * @brief Configure MAC address filtering
 * @param[in] interface Underlying network interface
 * @return Error code
 **/
 
error_t nuc472EthUpdateMacAddrFilter(NetInterface *interface)
{
   uint_t i;
   bool_t acceptMulticast;
 
   //Debug message
   TRACE_DEBUG("Updating MAC filter...\r\n");
 
   //This flag will be set if multicast addresses should be accepted
   acceptMulticast = FALSE;
 
   //The MAC address filter contains the list of MAC addresses to accept
   //when receiving an Ethernet frame
   for(i = 0; i < MAC_ADDR_FILTER_SIZE; i++)
   {
      //Valid entry?
      if(interface->macAddrFilter[i].refCount > 0)
      {
         //Accept multicast addresses
         acceptMulticast = TRUE;
         //We are done
         break;
      }
   }
 
   //Enable or disable the reception of multicast frames
   if(acceptMulticast)
   {
      EMAC->CAMCTL |= EMAC_CAMCTL_AMP_Msk;
   }
   else
   {
      EMAC->CAMCTL &= ~EMAC_CAMCTL_AMP_Msk;
   }
 
   //Successful processing
   return NO_ERROR;
}
 
 
/**
 * @brief Adjust MAC configuration parameters for proper operation
 * @param[in] interface Underlying network interface
 * @return Error code
 **/
 
error_t nuc472EthUpdateMacConfig(NetInterface *interface)
{
   uint32_t config;
 
   //Read MAC control register
   config = EMAC->CTL;
 
   //10BASE-T or 100BASE-TX operation mode?
   if(interface->linkSpeed == NIC_LINK_SPEED_100MBPS)
   {
      config |= EMAC_CTL_OPMODE_Msk;
   }
   else
   {
      config &= ~EMAC_CTL_OPMODE_Msk;
   }
 
   //Half-duplex or full-duplex mode?
   if(interface->duplexMode == NIC_FULL_DUPLEX_MODE)
   {
      config |= EMAC_CTL_FUDUP_Msk;
   }
   else
   {
      config &= ~EMAC_CTL_FUDUP_Msk;
   }
 
   //Update MAC control register
   EMAC->CTL = config;
 
   //Successful processing
   return NO_ERROR;
}
 
 
/**
 * @brief Write PHY register
 * @param[in] opcode Access type (2 bits)
 * @param[in] phyAddr PHY address (5 bits)
 * @param[in] regAddr Register address (5 bits)
 * @param[in] data Register value
 **/
 
void nuc472EthWritePhyReg(uint8_t opcode, uint8_t phyAddr,
   uint8_t regAddr, uint16_t data)
{
   uint32_t temp;
 
   //Valid opcode?
   if(opcode == SMI_OPCODE_WRITE)
   {
      //Set up a write operation
      temp = EMAC_MIIMCTL_MDCON_Msk | EMAC_MIIMCTL_BUSY_Msk | EMAC_MIIMCTL_WRITE_Msk;
      //PHY address
      temp |= (phyAddr << EMAC_MIIMCTL_PHYADDR_Pos) & EMAC_MIIMCTL_PHYADDR_Msk;
      //Register address
      temp |= (regAddr << EMAC_MIIMCTL_PHYREG_Pos) & EMAC_MIIMCTL_PHYREG_Msk;
 
      //Data to be written in the PHY register
      EMAC->MIIMDAT = data & EMAC_MIIMDAT_DATA_Msk;
 
      //Start a write operation
      EMAC->MIIMCTL = temp;
      //Wait for the write to complete
      while((EMAC->MIIMCTL & EMAC_MIIMCTL_BUSY_Msk) != 0)
      {
      }
   }
   else
   {
      //The MAC peripheral only supports standard Clause 22 opcodes
   }
}
 
 
/**
 * @brief Read PHY register
 * @param[in] opcode Access type (2 bits)
 * @param[in] phyAddr PHY address (5 bits)
 * @param[in] regAddr Register address (5 bits)
 * @return Register value
 **/
 
uint16_t nuc472EthReadPhyReg(uint8_t opcode, uint8_t phyAddr,
   uint8_t regAddr)
{
   uint16_t data;
   uint32_t temp;
 
   //Valid opcode?
   if(opcode == SMI_OPCODE_READ)
   {
      //Set up a read operation
      temp = EMAC_MIIMCTL_MDCON_Msk | EMAC_MIIMCTL_BUSY_Msk;
      //PHY address
      temp |= (phyAddr << EMAC_MIIMCTL_PHYADDR_Pos) & EMAC_MIIMCTL_PHYADDR_Msk;
      //Register address
      temp |= (regAddr << EMAC_MIIMCTL_PHYREG_Pos) & EMAC_MIIMCTL_PHYREG_Msk;
 
      //Start a read operation
      EMAC->MIIMCTL = temp;
      //Wait for the read to complete
      while((EMAC->MIIMCTL & EMAC_MIIMCTL_BUSY_Msk) != 0)
      {
      }
 
      //Get register value
      data = EMAC->MIIMDAT & EMAC_MIIMDAT_DATA_Msk;
   }
   else
   {
      //The MAC peripheral only supports standard Clause 22 opcodes
      data = 0;
   }
 
   //Return the value of the PHY register
   return data;
}