Sergey Pastor
Webserver+3d print
Diff: cyclone_tcp/drivers/sam4e_eth.c
- Revision:
- 0:8918a71cdbe9
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/cyclone_tcp/drivers/sam4e_eth.c Sat Feb 04 18:15:49 2017 +0000
@@ -0,0 +1,724 @@
+/**
+ * @file sam4e_eth.c
+ * @brief SAM4E Ethernet MAC controller
+ *
+ * @section License
+ *
+ * Copyright (C) 2010-2017 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 1.7.6
+ **/
+
+//Switch to the appropriate trace level
+#define TRACE_LEVEL NIC_TRACE_LEVEL
+
+//Dependencies
+#include <limits.h>
+#include "sam4e.h"
+#include "core/net.h"
+#include "drivers/sam4e_eth.h"
+#include "debug.h"
+
+//Underlying network interface
+static NetInterface *nicDriverInterface;
+
+//IAR EWARM compiler?
+#if defined(__ICCARM__)
+
+//TX buffer
+#pragma data_alignment = 8
+static uint8_t txBuffer[SAM4E_ETH_TX_BUFFER_COUNT][SAM4E_ETH_TX_BUFFER_SIZE];
+//RX buffer
+#pragma data_alignment = 8
+static uint8_t rxBuffer[SAM4E_ETH_RX_BUFFER_COUNT][SAM4E_ETH_RX_BUFFER_SIZE];
+//TX buffer descriptors
+#pragma data_alignment = 4
+static Sam4eTxBufferDesc txBufferDesc[SAM4E_ETH_TX_BUFFER_COUNT];
+//RX buffer descriptors
+#pragma data_alignment = 4
+static Sam4eRxBufferDesc rxBufferDesc[SAM4E_ETH_RX_BUFFER_COUNT];
+
+//Keil MDK-ARM or GCC compiler?
+#else
+
+//TX buffer
+static uint8_t txBuffer[SAM4E_ETH_TX_BUFFER_COUNT][SAM4E_ETH_TX_BUFFER_SIZE]
+ __attribute__((aligned(8)));
+//RX buffer
+static uint8_t rxBuffer[SAM4E_ETH_RX_BUFFER_COUNT][SAM4E_ETH_RX_BUFFER_SIZE]
+ __attribute__((aligned(8)));
+//TX buffer descriptors
+static Sam4eTxBufferDesc txBufferDesc[SAM4E_ETH_TX_BUFFER_COUNT]
+ __attribute__((aligned(4)));
+//RX buffer descriptors
+static Sam4eRxBufferDesc rxBufferDesc[SAM4E_ETH_RX_BUFFER_COUNT]
+ __attribute__((aligned(4)));
+
+#endif
+
+//TX buffer index
+static uint_t txBufferIndex;
+//RX buffer index
+static uint_t rxBufferIndex;
+
+
+/**
+ * @brief SAM4E Ethernet MAC driver
+ **/
+
+const NicDriver sam4eEthDriver =
+{
+ NIC_TYPE_ETHERNET,
+ ETH_MTU,
+ sam4eEthInit,
+ sam4eEthTick,
+ sam4eEthEnableIrq,
+ sam4eEthDisableIrq,
+ sam4eEthEventHandler,
+ sam4eEthSendPacket,
+ sam4eEthSetMulticastFilter,
+ sam4eEthUpdateMacConfig,
+ sam4eEthWritePhyReg,
+ sam4eEthReadPhyReg,
+ TRUE,
+ TRUE,
+ TRUE,
+ FALSE
+};
+
+
+/**
+ * @brief SAM4E Ethernet MAC initialization
+ * @param[in] interface Underlying network interface
+ * @return Error code
+ **/
+
+error_t sam4eEthInit(NetInterface *interface)
+{
+ error_t error;
+ volatile uint32_t status;
+
+ //Debug message
+ TRACE_INFO("Initializing SAM4E Ethernet MAC...\r\n");
+
+ //Save underlying network interface
+ nicDriverInterface = interface;
+
+ //Enable GMAC peripheral clock
+ PMC->PMC_PCER1 = (1 << (ID_GMAC - 32));
+
+ //GPIO configuration
+ sam4eEthInitGpio(interface);
+
+ //Configure MDC clock speed
+ GMAC->GMAC_NCFGR = GMAC_NCFGR_CLK_MCK_96;
+ //Enable management port (MDC and MDIO)
+ GMAC->GMAC_NCR |= GMAC_NCR_MPE;
+
+ //PHY transceiver initialization
+ error = interface->phyDriver->init(interface);
+ //Failed to initialize PHY transceiver?
+ if(error)
+ return error;
+
+ //Set the MAC address
+ GMAC->GMAC_SA[0].GMAC_SAB = interface->macAddr.w[0] | (interface->macAddr.w[1] << 16);
+ GMAC->GMAC_SA[0].GMAC_SAT = interface->macAddr.w[2];
+
+ //Configure the receive filter
+ GMAC->GMAC_NCFGR |= GMAC_NCFGR_UNIHEN | GMAC_NCFGR_MTIHEN;
+
+ //Initialize hash table
+ GMAC->GMAC_HRB = 0;
+ GMAC->GMAC_HRT = 0;
+
+ //Initialize buffer descriptors
+ sam4eEthInitBufferDesc(interface);
+
+ //Clear transmit status register
+ GMAC->GMAC_TSR = GMAC_TSR_HRESP | GMAC_TSR_UND | GMAC_TSR_TXCOMP | GMAC_TSR_TFC |
+ GMAC_TSR_TXGO | GMAC_TSR_RLE | GMAC_TSR_COL | GMAC_TSR_UBR;
+ //Clear receive status register
+ GMAC->GMAC_RSR = GMAC_RSR_HNO | GMAC_RSR_RXOVR | GMAC_RSR_REC | GMAC_RSR_BNA;
+
+ //First disable all GMAC interrupts
+ GMAC->GMAC_IDR = 0xFFFFFFFF;
+ //Only the desired ones are enabled
+ GMAC->GMAC_IER = GMAC_IER_HRESP | GMAC_IER_ROVR | GMAC_IER_TCOMP | GMAC_IER_TFC |
+ GMAC_IER_RLEX | GMAC_IER_TUR | GMAC_IER_RXUBR | GMAC_IER_RCOMP;
+
+ //Read GMAC ISR register to clear any pending interrupt
+ status = GMAC->GMAC_ISR;
+
+ //Set priority grouping (4 bits for pre-emption priority, no bits for subpriority)
+ NVIC_SetPriorityGrouping(SAM4E_ETH_IRQ_PRIORITY_GROUPING);
+
+ //Configure GMAC interrupt priority
+ NVIC_SetPriority(GMAC_IRQn, NVIC_EncodePriority(SAM4E_ETH_IRQ_PRIORITY_GROUPING,
+ SAM4E_ETH_IRQ_GROUP_PRIORITY, SAM4E_ETH_IRQ_SUB_PRIORITY));
+
+ //Enable the GMAC to transmit and receive data
+ GMAC->GMAC_NCR |= GMAC_NCR_TXEN | GMAC_NCR_RXEN;
+
+ //Accept any packets from the upper layer
+ osSetEvent(&interface->nicTxEvent);
+
+ //Successful initialization
+ return NO_ERROR;
+}
+
+
+//SAM4E-EK or SAM4E-Xplained-Pro evaluation board?
+#if defined(USE_SAM4E_EK) || defined(USE_SAM4E_XPLAINED_PRO)
+
+/**
+ * @brief GPIO configuration
+ * @param[in] interface Underlying network interface
+ **/
+
+void sam4eEthInitGpio(NetInterface *interface)
+{
+ //Enable PIO peripheral clock
+ PMC->PMC_PCER0 = (1 << ID_PIOD);
+
+ //Disable pull-up resistors on MII pins
+ PIOD->PIO_PUDR = GMAC_MII_MASK;
+ //Disable interrupts-on-change
+ PIOD->PIO_IDR = GMAC_MII_MASK;
+ //Assign MII pins to peripheral A function
+ PIOD->PIO_ABCDSR[0] &= ~GMAC_MII_MASK;
+ PIOD->PIO_ABCDSR[1] &= ~GMAC_MII_MASK;
+ //Disable the PIO from controlling the corresponding pins
+ PIOD->PIO_PDR = GMAC_MII_MASK;
+
+ //Select MII operation mode
+ GMAC->GMAC_UR = GMAC_UR_RMIIMII;
+}
+
+#endif
+
+
+/**
+ * @brief Initialize buffer descriptors
+ * @param[in] interface Underlying network interface
+ **/
+
+void sam4eEthInitBufferDesc(NetInterface *interface)
+{
+ uint_t i;
+ uint32_t address;
+
+ //Initialize TX buffer descriptors
+ for(i = 0; i < SAM4E_ETH_TX_BUFFER_COUNT; i++)
+ {
+ //Calculate the address of the current TX buffer
+ address = (uint32_t) txBuffer[i];
+ //Write the address to the descriptor entry
+ txBufferDesc[i].address = address;
+ //Initialize status field
+ txBufferDesc[i].status = GMAC_TX_USED;
+ }
+
+ //Mark the last descriptor entry with the wrap flag
+ txBufferDesc[i - 1].status |= GMAC_TX_WRAP;
+ //Initialize TX buffer index
+ txBufferIndex = 0;
+
+ //Initialize RX buffer descriptors
+ for(i = 0; i < SAM4E_ETH_RX_BUFFER_COUNT; i++)
+ {
+ //Calculate the address of the current RX buffer
+ address = (uint32_t) rxBuffer[i];
+ //Write the address to the descriptor entry
+ rxBufferDesc[i].address = address & GMAC_RX_ADDRESS;
+ //Clear status field
+ rxBufferDesc[i].status = 0;
+ }
+
+ //Mark the last descriptor entry with the wrap flag
+ rxBufferDesc[i - 1].address |= GMAC_RX_WRAP;
+ //Initialize RX buffer index
+ rxBufferIndex = 0;
+
+ //Start location of the TX descriptor list
+ GMAC->GMAC_TBQB = (uint32_t) txBufferDesc;
+ //Start location of the RX descriptor list
+ GMAC->GMAC_RBQB = (uint32_t) rxBufferDesc;
+}
+
+
+/**
+ * @brief SAM4E 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 sam4eEthTick(NetInterface *interface)
+{
+ //Handle periodic operations
+ interface->phyDriver->tick(interface);
+}
+
+
+/**
+ * @brief Enable interrupts
+ * @param[in] interface Underlying network interface
+ **/
+
+void sam4eEthEnableIrq(NetInterface *interface)
+{
+ //Enable Ethernet MAC interrupts
+ NVIC_EnableIRQ(GMAC_IRQn);
+ //Enable Ethernet PHY interrupts
+ interface->phyDriver->enableIrq(interface);
+}
+
+
+/**
+ * @brief Disable interrupts
+ * @param[in] interface Underlying network interface
+ **/
+
+void sam4eEthDisableIrq(NetInterface *interface)
+{
+ //Disable Ethernet MAC interrupts
+ NVIC_DisableIRQ(GMAC_IRQn);
+ //Disable Ethernet PHY interrupts
+ interface->phyDriver->disableIrq(interface);
+}
+
+
+/**
+ * @brief SAM4E Ethernet MAC interrupt service routine
+ **/
+
+void GMAC_Handler(void)
+{
+ bool_t flag;
+ volatile uint32_t isr;
+ volatile uint32_t tsr;
+ volatile uint32_t rsr;
+
+ //Enter interrupt service routine
+ osEnterIsr();
+
+ //This flag will be set if a higher priority task must be woken
+ flag = FALSE;
+
+ //Each time the software reads GMAC_ISR, it has to check the
+ //contents of GMAC_TSR, GMAC_RSR and GMAC_NSR
+ isr = GMAC->GMAC_ISR;
+ tsr = GMAC->GMAC_TSR;
+ rsr = GMAC->GMAC_RSR;
+
+ //A packet has been transmitted?
+ if(tsr & (GMAC_TSR_HRESP | GMAC_TSR_UND | GMAC_TSR_TXCOMP | GMAC_TSR_TFC |
+ GMAC_TSR_TXGO | GMAC_TSR_RLE | GMAC_TSR_COL | GMAC_TSR_UBR))
+ {
+ //Only clear TSR flags that are currently set
+ GMAC->GMAC_TSR = tsr;
+
+ //Check whether the TX buffer is available for writing
+ if(txBufferDesc[txBufferIndex].status & GMAC_TX_USED)
+ {
+ //Notify the TCP/IP stack that the transmitter is ready to send
+ flag |= osSetEventFromIsr(&nicDriverInterface->nicTxEvent);
+ }
+ }
+
+ //A packet has been received?
+ if(rsr & (GMAC_RSR_HNO | GMAC_RSR_RXOVR | GMAC_RSR_REC | GMAC_RSR_BNA))
+ {
+ //Set event flag
+ nicDriverInterface->nicEvent = TRUE;
+ //Notify the TCP/IP stack of the event
+ flag |= osSetEventFromIsr(&netEvent);
+ }
+
+ //Leave interrupt service routine
+ osExitIsr(flag);
+}
+
+
+/**
+ * @brief SAM4E Ethernet MAC event handler
+ * @param[in] interface Underlying network interface
+ **/
+
+void sam4eEthEventHandler(NetInterface *interface)
+{
+ error_t error;
+ uint32_t rsr;
+
+ //Read receive status
+ rsr = GMAC->GMAC_RSR;
+
+ //Packet received?
+ if(rsr & (GMAC_RSR_HNO | GMAC_RSR_RXOVR | GMAC_RSR_REC | GMAC_RSR_BNA))
+ {
+ //Only clear RSR flags that are currently set
+ GMAC->GMAC_RSR = rsr;
+
+ //Process all pending packets
+ do
+ {
+ //Read incoming packet
+ error = sam4eEthReceivePacket(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
+ * @return Error code
+ **/
+
+error_t sam4eEthSendPacket(NetInterface *interface,
+ const NetBuffer *buffer, size_t offset)
+{
+ size_t length;
+
+ //Retrieve the length of the packet
+ length = netBufferGetLength(buffer) - offset;
+
+ //Check the frame length
+ if(length > SAM4E_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(!(txBufferDesc[txBufferIndex].status & GMAC_TX_USED))
+ return ERROR_FAILURE;
+
+ //Copy user data to the transmit buffer
+ netBufferRead(txBuffer[txBufferIndex], buffer, offset, length);
+
+ //Set the necessary flags in the descriptor entry
+ if(txBufferIndex < (SAM4E_ETH_TX_BUFFER_COUNT - 1))
+ {
+ //Write the status word
+ txBufferDesc[txBufferIndex].status =
+ GMAC_TX_LAST | (length & GMAC_TX_LENGTH);
+
+ //Point to the next buffer
+ txBufferIndex++;
+ }
+ else
+ {
+ //Write the status word
+ txBufferDesc[txBufferIndex].status = GMAC_TX_WRAP |
+ GMAC_TX_LAST | (length & GMAC_TX_LENGTH);
+
+ //Wrap around
+ txBufferIndex = 0;
+ }
+
+ //Set the TSTART bit to initiate transmission
+ GMAC->GMAC_NCR |= GMAC_NCR_TSTART;
+
+ //Check whether the next buffer is available for writing
+ if(txBufferDesc[txBufferIndex].status & GMAC_TX_USED)
+ {
+ //The transmitter can accept another packet
+ osSetEvent(&interface->nicTxEvent);
+ }
+
+ //Successful processing
+ return NO_ERROR;
+}
+
+
+/**
+ * @brief Receive a packet
+ * @param[in] interface Underlying network interface
+ * @return Error code
+ **/
+
+error_t sam4eEthReceivePacket(NetInterface *interface)
+{
+ static uint8_t temp[ETH_MAX_FRAME_SIZE];
+ error_t error;
+ uint_t i;
+ uint_t j;
+ uint_t sofIndex;
+ uint_t eofIndex;
+ size_t n;
+ size_t size;
+ size_t length;
+
+ //Initialize SOF and EOF indices
+ sofIndex = UINT_MAX;
+ eofIndex = UINT_MAX;
+
+ //Search for SOF and EOF flags
+ for(i = 0; i < SAM4E_ETH_RX_BUFFER_COUNT; i++)
+ {
+ //Point to the current entry
+ j = rxBufferIndex + i;
+
+ //Wrap around to the beginning of the buffer if necessary
+ if(j >= SAM4E_ETH_RX_BUFFER_COUNT)
+ j -= SAM4E_ETH_RX_BUFFER_COUNT;
+
+ //No more entries to process?
+ if(!(rxBufferDesc[j].address & GMAC_RX_OWNERSHIP))
+ {
+ //Stop processing
+ break;
+ }
+ //A valid SOF has been found?
+ if(rxBufferDesc[j].status & GMAC_RX_SOF)
+ {
+ //Save the position of the SOF
+ sofIndex = i;
+ }
+ //A valid EOF has been found?
+ if((rxBufferDesc[j].status & GMAC_RX_EOF) && sofIndex != UINT_MAX)
+ {
+ //Save the position of the EOF
+ eofIndex = i;
+ //Retrieve the length of the frame
+ size = rxBufferDesc[j].status & GMAC_RX_LENGTH;
+ //Limit the number of data to read
+ size = MIN(size, ETH_MAX_FRAME_SIZE);
+ //Stop processing since we have reached the end of the frame
+ break;
+ }
+ }
+
+ //Determine the number of entries to process
+ if(eofIndex != UINT_MAX)
+ j = eofIndex + 1;
+ else if(sofIndex != UINT_MAX)
+ j = sofIndex;
+ else
+ j = i;
+
+ //Total number of bytes that have been copied from the receive buffer
+ length = 0;
+
+ //Process incoming frame
+ for(i = 0; i < j; i++)
+ {
+ //Any data to copy from current buffer?
+ if(eofIndex != UINT_MAX && i >= sofIndex && i <= eofIndex)
+ {
+ //Calculate the number of bytes to read at a time
+ n = MIN(size, SAM4E_ETH_RX_BUFFER_SIZE);
+ //Copy data from receive buffer
+ memcpy(temp + length, rxBuffer[rxBufferIndex], n);
+ //Update byte counters
+ length += n;
+ size -= n;
+ }
+
+ //Mark the current buffer as free
+ rxBufferDesc[rxBufferIndex].address &= ~GMAC_RX_OWNERSHIP;
+
+ //Point to the following entry
+ rxBufferIndex++;
+
+ //Wrap around to the beginning of the buffer if necessary
+ if(rxBufferIndex >= SAM4E_ETH_RX_BUFFER_COUNT)
+ rxBufferIndex = 0;
+ }
+
+ //Any packet to process?
+ if(length > 0)
+ {
+ //Pass the packet to the upper layer
+ nicProcessPacket(interface, temp, length);
+ //Valid packet received
+ error = NO_ERROR;
+ }
+ else
+ {
+ //No more data in the receive buffer
+ error = ERROR_BUFFER_EMPTY;
+ }
+
+ //Return status code
+ return error;
+}
+
+
+/**
+ * @brief Configure multicast MAC address filtering
+ * @param[in] interface Underlying network interface
+ * @return Error code
+ **/
+
+error_t sam4eEthSetMulticastFilter(NetInterface *interface)
+{
+ uint_t i;
+ uint_t k;
+ uint8_t *p;
+ uint32_t hashTable[2];
+ MacFilterEntry *entry;
+
+ //Debug message
+ TRACE_DEBUG("Updating SAM4E hash table...\r\n");
+
+ //Clear hash table
+ hashTable[0] = 0;
+ hashTable[1] = 0;
+
+ //The MAC filter table contains the multicast MAC addresses
+ //to accept when receiving an Ethernet frame
+ for(i = 0; i < MAC_MULTICAST_FILTER_SIZE; i++)
+ {
+ //Point to the current entry
+ entry = &interface->macMulticastFilter[i];
+
+ //Valid entry?
+ if(entry->refCount > 0)
+ {
+ //Point to the MAC address
+ p = entry->addr.b;
+
+ //Apply the hash function
+ k = (p[0] >> 6) ^ p[0];
+ k ^= (p[1] >> 4) ^ (p[1] << 2);
+ k ^= (p[2] >> 2) ^ (p[2] << 4);
+ k ^= (p[3] >> 6) ^ p[3];
+ k ^= (p[4] >> 4) ^ (p[4] << 2);
+ k ^= (p[5] >> 2) ^ (p[5] << 4);
+
+ //The hash value is reduced to a 6-bit index
+ k &= 0x3F;
+
+ //Update hash table contents
+ hashTable[k / 32] |= (1 << (k % 32));
+ }
+ }
+
+ //Write the hash table
+ GMAC->GMAC_HRB = hashTable[0];
+ GMAC->GMAC_HRT = hashTable[1];
+
+ //Debug message
+ TRACE_DEBUG(" HRB = %08" PRIX32 "\r\n", GMAC->GMAC_HRB);
+ TRACE_DEBUG(" HRT = %08" PRIX32 "\r\n", GMAC->GMAC_HRT);
+
+ //Successful processing
+ return NO_ERROR;
+}
+
+
+/**
+ * @brief Adjust MAC configuration parameters for proper operation
+ * @param[in] interface Underlying network interface
+ * @return Error code
+ **/
+
+error_t sam4eEthUpdateMacConfig(NetInterface *interface)
+{
+ uint32_t config;
+
+ //Read network configuration register
+ config = GMAC->GMAC_NCFGR;
+
+ //10BASE-T or 100BASE-TX operation mode?
+ if(interface->linkSpeed == NIC_LINK_SPEED_100MBPS)
+ config |= GMAC_NCFGR_SPD;
+ else
+ config &= ~GMAC_NCFGR_SPD;
+
+ //Half-duplex or full-duplex mode?
+ if(interface->duplexMode == NIC_FULL_DUPLEX_MODE)
+ config |= GMAC_NCFGR_FD;
+ else
+ config &= ~GMAC_NCFGR_FD;
+
+ //Write configuration value back to NCFGR register
+ GMAC->GMAC_NCFGR = config;
+
+ //Successful processing
+ return NO_ERROR;
+}
+
+
+/**
+ * @brief Write PHY register
+ * @param[in] phyAddr PHY address
+ * @param[in] regAddr Register address
+ * @param[in] data Register value
+ **/
+
+void sam4eEthWritePhyReg(uint8_t phyAddr, uint8_t regAddr, uint16_t data)
+{
+ uint32_t value;
+
+ //Set up a write operation
+ value = GMAC_MAN_CLTTO | GMAC_MAN_OP(1) | GMAC_MAN_WTN(2);
+ //PHY address
+ value |= GMAC_MAN_PHYA(phyAddr);
+ //Register address
+ value |= GMAC_MAN_REGA(regAddr);
+ //Register value
+ value |= GMAC_MAN_DATA(data);
+
+ //Start a write operation
+ GMAC->GMAC_MAN = value;
+ //Wait for the write to complete
+ while(!(GMAC->GMAC_NSR & GMAC_NSR_IDLE));
+}
+
+
+/**
+ * @brief Read PHY register
+ * @param[in] phyAddr PHY address
+ * @param[in] regAddr Register address
+ * @return Register value
+ **/
+
+uint16_t sam4eEthReadPhyReg(uint8_t phyAddr, uint8_t regAddr)
+{
+ uint32_t value;
+
+ //Set up a read operation
+ value = GMAC_MAN_CLTTO | GMAC_MAN_OP(2) | GMAC_MAN_WTN(2);
+ //PHY address
+ value |= GMAC_MAN_PHYA(phyAddr);
+ //Register address
+ value |= GMAC_MAN_REGA(regAddr);
+
+ //Start a read operation
+ GMAC->GMAC_MAN = value;
+ //Wait for the read to complete
+ while(!(GMAC->GMAC_NSR & GMAC_NSR_IDLE));
+
+ //Return PHY register contents
+ return GMAC->GMAC_MAN & GMAC_MAN_DATA_Msk;
+}
+