From 06eece0c95b654505d0340031bd2614fb920db04 Mon Sep 17 00:00:00 2001
From: Hein Tibosch <hein@htibosch.net>
Date: Wed, 2 Nov 2022 16:15:11 +0800
Subject: [PATCH 1/7] Implemented Maty's solution

---
 .../DriverSAM/NetworkInterface.c              | 106 ++++++++++--------
 .../NetworkInterface/DriverSAM/gmac_SAM.c     |  67 ++++++-----
 .../NetworkInterface/DriverSAM/gmac_SAM.h     |  26 ++++-
 3 files changed, 125 insertions(+), 74 deletions(-)

diff --git a/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c b/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c
index 402865aaf7..4c9d3952af 100644
--- a/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c
+++ b/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c
@@ -53,6 +53,15 @@
 /* This file is included to see if 'CONF_BOARD_ENABLE_CACHE' is defined. */
 #include "conf_board.h"
 
+/* The SAME70 family has the possibility of caching RAM.
+ * 'NETWORK_BUFFERS_CACHED' can be defined in either "conf_eth.h"
+ * or in "FreeRTOSIPConfig.h".
+ * For now, NETWORK_BUFFERS_CACHED should be defined as zero.
+ * D-cache may be enabled.
+ */
+#if ( NETWORK_BUFFERS_CACHED != 0 )
+    #error please define this macro as zero
+#endif
 
 /* Interrupt events to process.  Currently only the Rx event is processed
  * although code for other events is included to allow for possible future
@@ -95,10 +104,9 @@
     #define niEMAC_HANDLER_TASK_PRIORITY    configMAX_PRIORITIES - 1
 #endif
 
-#if ( __DCACHE_PRESENT != 0 ) && defined( CONF_BOARD_ENABLE_CACHE )
+#if ( NETWORK_BUFFERS_CACHED != 0 ) && ( __DCACHE_PRESENT != 0 ) && defined( CONF_BOARD_ENABLE_CACHE )
     #include "core_cm7.h"
     #warning This driver assumes the presence of DCACHE
-    #define     NETWORK_BUFFERS_CACHED        1
     #define     CACHE_LINE_SIZE               32
     #define     NETWORK_BUFFER_HEADER_SIZE    ( ipconfigPACKET_FILLER_SIZE + 8 )
 
@@ -113,26 +121,24 @@
                                                 uint32_t size )
     {
         /* SAME70 does not have clean/invalidate per area. */
-        /* SCB_CleanInvalidateDCache_by_Addr( ( uint32_t * )addr, size); */
-        SCB_CleanInvalidateDCache();
+        SCB_CleanInvalidateDCache_by_Addr( ( uint32_t * ) addr, size );
     }
     /*-----------------------------------------------------------*/
 
-    static void cache_invalidate_by_addr( addr,
-                                          size ) \
+    static void cache_invalidate_by_addr( uint32_t addr,
+                                          uint32_t size )
     {
         /* SAME70 does not have clean/invalidate per area. */
-        /* SCB_InvalidateDCache_by_Addr( ( uint32_t * )addr, size); */
-        SCB_InvalidateDCache();
+        SCB_InvalidateDCache_by_Addr( ( uint32_t * ) addr, size );
     }
     /*-----------------------------------------------------------*/
 
-#else /* if ( __DCACHE_PRESENT != 0 ) && defined( CONF_BOARD_ENABLE_CACHE ) */
+#else /* The DMA buffers are located in non-cached RAM. */
     #warning Sure there is no caching?
     #define     cache_clean_invalidate()                        do {} while( 0 )
     #define     cache_clean_invalidate_by_addr( addr, size )    do {} while( 0 )
     #define     cache_invalidate_by_addr( addr, size )          do {} while( 0 )
-#endif /* if ( __DCACHE_PRESENT != 0 ) && defined( CONF_BOARD_ENABLE_CACHE ) */
+#endif /* if ( NETWORK_BUFFERS_CACHED != 0 ) && ( __DCACHE_PRESENT != 0 ) && defined( CONF_BOARD_ENABLE_CACHE ) */
 
 /*-----------------------------------------------------------*/
 
@@ -186,11 +192,6 @@ static void hand_tx_errors( void );
 
 /*-----------------------------------------------------------*/
 
-/* Bit map of outstanding ETH interrupt events for processing.  Currently only
- * the Rx interrupt is handled, although code is included for other events to
- * enable future expansion. */
-static volatile uint32_t ulISREvents;
-
 /* A copy of PHY register 1: 'PHY_REG_01_BMSR' */
 static volatile BaseType_t xGMACSwitchRequired;
 
@@ -205,8 +206,9 @@ static gmac_device_t gs_gmac_dev;
  * related interrupts. */
 TaskHandle_t xEMACTaskHandle = NULL;
 
+/* TX buffers that have been sent must be returned to the driver
+ * using this queue. */
 static QueueHandle_t xTxBufferQueue;
-int tx_release_count[ 4 ];
 
 /* xTXDescriptorSemaphore is a counting semaphore with
  * a maximum count of GMAC_TX_BUFFERS, which is the number of
@@ -271,21 +273,21 @@ void xRxCallback( uint32_t ulStatus )
     if( ( ( ulStatus & GMAC_RSR_REC ) != 0 ) && ( xEMACTaskHandle != NULL ) )
     {
         /* let the prvEMACHandlerTask know that there was an RX event. */
-        ulISREvents |= EMAC_IF_RX_EVENT;
-        /* Only an RX interrupt can wakeup prvEMACHandlerTask. */
-        vTaskNotifyGiveFromISR( xEMACTaskHandle, ( BaseType_t * ) &xGMACSwitchRequired );
+        xTaskNotifyFromISR( xEMACTaskHandle, EMAC_IF_RX_EVENT, eSetBits, &( xGMACSwitchRequired ) );
     }
 }
 /*-----------------------------------------------------------*/
 
+/* The following function can be called by gmac_reset_tx_mem().
+ */
 void returnTxBuffer( uint8_t * puc_buffer )
 {
     /* Called from a non-ISR context. */
     if( xTxBufferQueue != NULL )
     {
+        /* return 'puc_buffer' to the pool of transmission buffers. */
         xQueueSend( xTxBufferQueue, &puc_buffer, 0 );
-        xTaskNotifyGive( xEMACTaskHandle );
-        ulISREvents |= EMAC_IF_TX_EVENT;
+        xTaskNotify( xEMACTaskHandle, EMAC_IF_TX_EVENT, eSetBits );
     }
 }
 
@@ -295,11 +297,21 @@ void xTxCallback( uint32_t ulStatus,
     if( ( xTxBufferQueue != NULL ) && ( xEMACTaskHandle != NULL ) )
     {
         /* let the prvEMACHandlerTask know that there was an TX event. */
-        ulISREvents |= EMAC_IF_TX_EVENT;
         /* Wakeup prvEMACHandlerTask. */
-        vTaskNotifyGiveFromISR( xEMACTaskHandle, ( BaseType_t * ) &xGMACSwitchRequired );
-        xQueueSendFromISR( xTxBufferQueue, &puc_buffer, ( BaseType_t * ) &xGMACSwitchRequired );
-        tx_release_count[ 2 ]++;
+        if( puc_buffer == NULL )
+        {
+            /* (GMAC_TSR) Retry Limit Exceeded */
+            /* Can not send logging, we're in an ISR. */
+        }
+        else
+        {
+            xQueueSendFromISR( xTxBufferQueue, &puc_buffer, ( BaseType_t * ) &xGMACSwitchRequired );
+            xTaskNotifyFromISR( xEMACTaskHandle, EMAC_IF_TX_EVENT, eSetBits, &( xGMACSwitchRequired ) );
+
+            /* TX statistics. Only works when 'GMAC_STATS'
+             * is defined as 1.  See gmac_SAM.h for more information. */
+            TX_STAT_INCREMENT( tx_callback );
+        }
     }
 }
 /*-----------------------------------------------------------*/
@@ -445,7 +457,9 @@ BaseType_t xNetworkInterfaceInitialise( void )
 
     if( xTXDescriptorSemaphore == NULL )
     {
-        xTXDescriptorSemaphore = xSemaphoreCreateCounting( ( UBaseType_t ) GMAC_TX_BUFFERS, ( UBaseType_t ) GMAC_TX_BUFFERS );
+        /* When there are N TX descriptors, we want to use
+         * at most "N-1" simultaneously. */
+        xTXDescriptorSemaphore = xSemaphoreCreateCounting( ( UBaseType_t ) GMAC_TX_BUFFERS - 1U, ( UBaseType_t ) GMAC_TX_BUFFERS - 1U );
         configASSERT( xTXDescriptorSemaphore );
     }
 
@@ -483,7 +497,6 @@ static void hand_tx_errors( void )
         gmac_enable_transmit( GMAC, false );
 
         /* Reinit TX descriptors. */
-/*		gmac_tx_init(ps_gmac_dev); */
         gmac_reset_tx_mem( &gs_gmac_dev );
         /* Clear error status. */
         gmac_clear_tx_status( GMAC, GMAC_TX_ERRORS );
@@ -498,7 +511,7 @@ BaseType_t xNetworkInterfaceOutput( NetworkBufferDescriptor_t * const pxDescript
                                     BaseType_t bReleaseAfterSend )
 {
 /* Do not wait too long for a free TX DMA buffer. */
-    const TickType_t xBlockTimeTicks = pdMS_TO_TICKS( 50u );
+    const TickType_t xBlockTimeTicks = pdMS_TO_TICKS( 50U );
     uint32_t ulTransmitSize;
 
     ulTransmitSize = pxDescriptor->xDataLength;
@@ -514,6 +527,8 @@ BaseType_t xNetworkInterfaceOutput( NetworkBufferDescriptor_t * const pxDescript
      * statement. */
     do
     {
+        uint32_t ulResult;
+
         if( xPhyObject.ulLinkStatusMask == 0ul )
         {
             /* Do not attempt to send packets as long as the Link Status is low. */
@@ -531,10 +546,11 @@ BaseType_t xNetworkInterfaceOutput( NetworkBufferDescriptor_t * const pxDescript
         if( xSemaphoreTake( xTXDescriptorSemaphore, xBlockTimeTicks ) != pdPASS )
         {
             /* Time-out waiting for a free TX descriptor. */
-            tx_release_count[ 3 ]++;
+            TX_STAT_INCREMENT( tx_enqueue_fail );
             break;
         }
 
+        TX_STAT_INCREMENT( tx_enqueue_ok );
         #if ( ipconfigZERO_COPY_TX_DRIVER != 0 )
             {
                 /* Confirm that the pxDescriptor may be kept by the driver. */
@@ -550,7 +566,8 @@ BaseType_t xNetworkInterfaceOutput( NetworkBufferDescriptor_t * const pxDescript
             }
         #endif
 
-        gmac_dev_write( &gs_gmac_dev, ( void * ) pxDescriptor->pucEthernetBuffer, pxDescriptor->xDataLength );
+        ulResult = gmac_dev_write( &gs_gmac_dev, ( void * ) pxDescriptor->pucEthernetBuffer, pxDescriptor->xDataLength );
+        configASSERT( ulResult == GMAC_OK )
 
         #if ( ipconfigZERO_COPY_TX_DRIVER != 0 )
             {
@@ -594,7 +611,7 @@ static BaseType_t prvGMACInit( void )
 
     {
         /* Set MDC clock divider. */
-        gmac_set_mdc_clock( GMAC, sysclk_get_cpu_hz() );
+        gmac_set_mdc_clock( GMAC, sysclk_get_peripheral_hz() );
 
         vPhyInitialise( &xPhyObject, xPHY_Read, xPHY_Write );
         xPhyDiscover( &xPhyObject );
@@ -840,7 +857,7 @@ void vNetworkInterfaceAllocateRAMToBuffers( NetworkBufferDescriptor_t pxNetworkB
 static void prvEMACHandlerTask( void * pvParameters )
 {
     UBaseType_t uxCount;
-    UBaseType_t uxLowestSemCount = 0;
+    UBaseType_t uxLowestSemCount = GMAC_TX_BUFFERS + 1;
 
     #if ( ipconfigZERO_COPY_TX_DRIVER != 0 )
         NetworkBufferDescriptor_t * pxBuffer;
@@ -849,6 +866,7 @@ static void prvEMACHandlerTask( void * pvParameters )
     BaseType_t xResult = 0;
     uint32_t xStatus;
     const TickType_t ulMaxBlockTime = pdMS_TO_TICKS( EMAC_MAX_BLOCK_TIME_MS );
+    uint32_t ulISREvents = 0U;
 
     /* Remove compiler warnings about unused parameters. */
     ( void ) pvParameters;
@@ -879,16 +897,14 @@ static void prvEMACHandlerTask( void * pvParameters )
             }
         #endif /* ( ipconfigHAS_PRINTF != 0 ) */
 
-        if( ( ulISREvents & EMAC_IF_ALL_EVENT ) == 0 )
-        {
-            /* No events to process now, wait for the next. */
-            ulTaskNotifyTake( pdFALSE, ulMaxBlockTime );
-        }
+        /* Wait for a new event or a time-out. */
+        xTaskNotifyWait( 0U,                /* ulBitsToClearOnEntry */
+                         EMAC_IF_ALL_EVENT, /* ulBitsToClearOnExit */
+                         &( ulISREvents ),  /* pulNotificationValue */
+                         ulMaxBlockTime );
 
         if( ( ulISREvents & EMAC_IF_RX_EVENT ) != 0 )
         {
-            ulISREvents &= ~EMAC_IF_RX_EVENT;
-
             /* Wait for the EMAC interrupt to indicate that another packet has been
              * received. */
             xResult = prvEMACRxPoll();
@@ -896,9 +912,6 @@ static void prvEMACHandlerTask( void * pvParameters )
 
         if( ( ulISREvents & EMAC_IF_TX_EVENT ) != 0 )
         {
-            /* Future extension: code to release TX buffers if zero-copy is used. */
-            ulISREvents &= ~EMAC_IF_TX_EVENT;
-
             while( xQueueReceive( xTxBufferQueue, &pucBuffer, 0 ) != pdFALSE )
             {
                 #if ( ipconfigZERO_COPY_TX_DRIVER != 0 )
@@ -908,21 +921,21 @@ static void prvEMACHandlerTask( void * pvParameters )
                         if( pxBuffer != NULL )
                         {
                             vReleaseNetworkBufferAndDescriptor( pxBuffer );
-                            tx_release_count[ 0 ]++;
+                            TX_STAT_INCREMENT( tx_release_ok );
                         }
                         else
                         {
-                            tx_release_count[ 1 ]++;
+                            TX_STAT_INCREMENT( tx_release_bad );
                         }
                     }
                 #else /* if ( ipconfigZERO_COPY_TX_DRIVER != 0 ) */
                     {
-                        tx_release_count[ 0 ]++;
+                        TX_STAT_INCREMENT( tx_release_ok );
                     }
                 #endif /* if ( ipconfigZERO_COPY_TX_DRIVER != 0 ) */
                 uxCount = uxQueueMessagesWaiting( ( QueueHandle_t ) xTXDescriptorSemaphore );
 
-                if( uxCount < GMAC_TX_BUFFERS )
+                if( uxCount < ( GMAC_TX_BUFFERS - 1 ) )
                 {
                     /* Tell the counting semaphore that one more TX descriptor is available. */
                     xSemaphoreGive( xTXDescriptorSemaphore );
@@ -933,7 +946,6 @@ static void prvEMACHandlerTask( void * pvParameters )
         if( ( ulISREvents & EMAC_IF_ERR_EVENT ) != 0 )
         {
             /* Future extension: logging about errors that occurred. */
-            ulISREvents &= ~EMAC_IF_ERR_EVENT;
         }
 
         gmac_enable_management( GMAC, true );
diff --git a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
index 7b2d445f7c..eab7fc726e 100644
--- a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
+++ b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
@@ -89,11 +89,20 @@
 #endif
 
 #if ( GMAC_RX_BUFFERS <= 1 )
-    #error Configuration error
+    #error Configuration error, GMAC_RX_BUFFERS must be at least 2
 #endif
 
 #if ( GMAC_TX_BUFFERS <= 1 )
-    #error Configuration error
+    #error Configuration error, GMAC_TX_BUFFERS must be at least 2
+#endif
+
+/* Interesting bits in the Transmission Status Register. */
+#define TSR_TSR_BITS    ( GMAC_TSR_TXCOMP | GMAC_TSR_COL | GMAC_TSR_RLE | GMAC_TSR_UND )
+
+#if ( GMAC_STATS != 0 )
+    #warning Statistics are enabled
+    struct SGmacStats gmacStats;
+    TransmitStats_t xTransmitStats;
 #endif
 
 /**
@@ -488,12 +497,6 @@ static uint32_t gmac_dev_poll( gmac_device_t * p_gmac_dev )
     int32_t ulIndex = p_gmac_dev->ul_rx_idx;
     gmac_rx_descriptor_t * pxHead = &gs_rx_desc[ ulIndex ];
 
-/*	#warning Just for debugging */
-/*	if((pxHead->addr.val & GMAC_RXD_OWNERSHIP) != 0) */
-/*	{ */
-/*		NVIC_DisableIRQ( GMAC_IRQn ); */
-/*	} */
-
     #if ( ipconfigZERO_COPY_RX_DRIVER == 0 )
         {
             /* Discard any incomplete frames */
@@ -616,7 +619,7 @@ uint32_t gmac_dev_read( gmac_device_t * p_gmac_dev,
     /* Read +2 bytes because buffers are aligned at -2 bytes */
     bytesLeft = min( bytesLeft + 2, ( int32_t ) ul_frame_size );
 
-    #if ( __DCACHE_PRESENT != 0 ) && defined( CONF_BOARD_ENABLE_CACHE )
+    #if ( NETWORK_BUFFERS_CACHED != 0 ) && ( __DCACHE_PRESENT != 0 ) && defined( CONF_BOARD_ENABLE_CACHE )
         SCB_InvalidateDCache();
     #endif
 
@@ -670,20 +673,25 @@ uint32_t gmac_dev_read( gmac_device_t * p_gmac_dev,
         pxHead = &gs_rx_desc[ nextIdx ];
         pxHead->addr.val &= ~( GMAC_RXD_OWNERSHIP );
         circ_inc32( &nextIdx, GMAC_RX_BUFFERS );
+
+        if( pxHead->addr.val )
+        {
+            /* Just read it back to make sure that
+             * it was written to SRAM. */
+        }
     } while( ( pxHead->status.val & GMAC_RXD_EOF ) == 0 );
 
     p_gmac_dev->ul_rx_idx = nextIdx;
 
     *p_rcv_size = bytesLeft;
 
-/*	#warning Just for debugging */
-/*	NVIC_EnableIRQ( GMAC_IRQn ); */
-
     return GMAC_OK;
 }
 
-extern void vGMACGenerateChecksum( uint8_t * apBuffer,
-                                   size_t uxLength );
+#if ( SAME70 == 0 )
+    extern void vGMACGenerateChecksum( uint8_t * apBuffer,
+                                       size_t uxLength );
+#endif
 
 /**
  * \brief Send ulLength bytes from pcFrom. This copies the buffer to one of the
@@ -705,6 +713,8 @@ uint32_t gmac_dev_write( gmac_device_t * p_gmac_dev,
 
     Gmac * p_hw = p_gmac_dev->p_hw;
 
+    configASSERT( p_buffer != NULL );
+    configASSERT( ul_size >= ipconfigETHERNET_MINIMUM_PACKET_BYTES );
 
     /* Check parameter */
     if( ul_size > GMAC_TX_UNITSIZE )
@@ -739,12 +749,15 @@ uint32_t gmac_dev_write( gmac_device_t * p_gmac_dev,
                 memcpy( ( void * ) p_tx_td->addr, p_buffer, ul_size );
             }
         #endif /* ipconfigZERO_COPY_TX_DRIVER */
-        vGMACGenerateChecksum( ( uint8_t * ) p_tx_td->addr, ( size_t ) ul_size );
+        #if ( SAME70 == 0 )
+            {
+                #warning Is this a SAM4E?
+                /* Needs to be called for SAM4E series only. */
+                vGMACGenerateChecksum( ( uint8_t * ) p_tx_td->addr, ( size_t ) ul_size );
+            }
+        #endif
     }
 
-    /*#warning Trying out */
-    gmac_start_transmission( p_hw );
-
     /* Update transmit descriptor status */
 
     /* The buffer size defined is the length of ethernet frame,
@@ -763,6 +776,12 @@ uint32_t gmac_dev_write( gmac_device_t * p_gmac_dev,
             ul_size | GMAC_TXD_LAST;
     }
 
+    if( p_tx_td->status.val )
+    {
+        /* Just read it back to make sure that
+         * it was written to SRAM. */
+    }
+
     circ_inc32( &p_gmac_dev->l_tx_head, GMAC_TX_BUFFERS );
 
     /* Now start to transmit if it is still not done */
@@ -862,9 +881,6 @@ void gmac_dev_halt( Gmac * p_gmac )
  */
 
 #if ( GMAC_STATS != 0 )
-    extern int logPrintf( const char * pcFormat,
-                          ... );
-
     void gmac_show_irq_counts()
     {
         int index;
@@ -873,7 +889,7 @@ void gmac_dev_halt( Gmac * p_gmac )
         {
             if( gmacStats.intStatus[ intPairs[ index ].index ] )
             {
-                logPrintf( "%s : %6u\n", intPairs[ index ].name, gmacStats.intStatus[ intPairs[ index ].index ] );
+                FreeRTOS_printf( ( "%s : %6u\n", intPairs[ index ].name, gmacStats.intStatus[ intPairs[ index ].index ] ) );
             }
         }
     }
@@ -922,7 +938,7 @@ void gmac_handler( gmac_device_t * p_gmac_dev )
     }
 
     /* TX packet */
-    if( ( ul_isr & GMAC_ISR_TCOMP ) || ( ul_tsr & ( GMAC_TSR_TXCOMP | GMAC_TSR_COL | GMAC_TSR_RLE | GMAC_TSR_UND ) ) )
+    if( ( ul_isr & GMAC_ISR_TCOMP ) || ( ( ul_tsr & TSR_TSR_BITS ) != 0U ) )
     {
         ul_tx_status_flag = GMAC_TSR_TXCOMP;
         /* A frame transmitted */
@@ -968,7 +984,8 @@ void gmac_handler( gmac_device_t * p_gmac_dev )
 
         if( ul_tsr & GMAC_TSR_RLE )
         {
-            /* Notify upper layer RLE */
+            /* Notify upper layer RLE
+             * (GMAC_TSR) Retry Limit Exceeded */
             xTxCallback( ul_tx_status_flag, NULL );
         }
 
@@ -991,7 +1008,7 @@ void gmac_handler( gmac_device_t * p_gmac_dev )
 /*/ @cond 0 */
 /**INDENT-OFF**/
 #ifdef __cplusplus
-    }
+}
 #endif
 /**INDENT-ON**/
 /*/ @endcond */
diff --git a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h
index 212e25ea3c..4ece496a12 100644
--- a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h
+++ b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h
@@ -1544,10 +1544,15 @@
 /**INDENT-ON**/
 /*/ @endcond */
 
+    #ifndef GMAC_STATS
+        #define GMAC_STATS    0
+    #endif
+
+    #if ( GMAC_STATS == 0 )
 
-    #define GMAC_STATS    0
+        #define TX_STAT_INCREMENT( field )    do {} while( ipFALSE_BOOL )
 
-    #if ( GMAC_STATS != 0 )
+    #else
 
 /* Here below some code to study the types and
  * frequencies of  GMAC interrupts. */
@@ -1599,6 +1604,23 @@
 
         void gmac_show_irq_counts();
 
+/*
+ *  The following struct replaces the earlier:
+ *      int tx_release_count[ 4 ];
+ *  The purpose of this struct is to describe the TX events.
+ */
+        typedef struct STransmitStats
+        {
+            unsigned tx_enqueue_ok;   /* xNetworkInterfaceOutput() success. */
+            unsigned tx_enqueue_fail; /* xNetworkInterfaceOutput() failed, no slot available. */
+            unsigned tx_callback;     /* Transmission ready, buffer returned to driver. */
+            unsigned tx_release_ok;   /* Buffer released. */
+            unsigned tx_release_bad;  /* Buffer corruption. */
+        } TransmitStats_t;
+
+        extern TransmitStats_t xTransmitStats;
+        #define TX_STAT_INCREMENT( field )    xTransmitStats.field++
+
     #endif /* if ( GMAC_STATS != 0 ) */
 
 #endif /* GMAC_H_INCLUDED */

From d89a334d51ed073ee78533befc9a3bc67377820c Mon Sep 17 00:00:00 2001
From: Hein Tibosch <hein@htibosch.net>
Date: Thu, 3 Nov 2022 11:07:44 +0800
Subject: [PATCH 2/7] Added a new statistic 'tx_write_fail'

---
 .../NetworkInterface/DriverSAM/NetworkInterface.c         | 8 ++++++--
 source/portable/NetworkInterface/DriverSAM/gmac_SAM.h     | 1 +
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c b/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c
index 4c9d3952af..7bbbc81425 100644
--- a/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c
+++ b/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c
@@ -193,7 +193,7 @@ static void hand_tx_errors( void );
 /*-----------------------------------------------------------*/
 
 /* A copy of PHY register 1: 'PHY_REG_01_BMSR' */
-static volatile BaseType_t xGMACSwitchRequired;
+static BaseType_t xGMACSwitchRequired;
 
 /* LLMNR multicast address. */
 static const uint8_t llmnr_mac_address[] = { 0x01, 0x00, 0x5E, 0x00, 0x00, 0xFC };
@@ -567,7 +567,11 @@ BaseType_t xNetworkInterfaceOutput( NetworkBufferDescriptor_t * const pxDescript
         #endif
 
         ulResult = gmac_dev_write( &gs_gmac_dev, ( void * ) pxDescriptor->pucEthernetBuffer, pxDescriptor->xDataLength );
-        configASSERT( ulResult == GMAC_OK )
+
+        if( ulResult != GMAC_OK )
+        {
+            TX_STAT_INCREMENT( tx_write_fail );
+        }
 
         #if ( ipconfigZERO_COPY_TX_DRIVER != 0 )
             {
diff --git a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h
index 4ece496a12..414300b875 100644
--- a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h
+++ b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h
@@ -1613,6 +1613,7 @@
         {
             unsigned tx_enqueue_ok;   /* xNetworkInterfaceOutput() success. */
             unsigned tx_enqueue_fail; /* xNetworkInterfaceOutput() failed, no slot available. */
+            unsigned tx_write_fail;   /* gmac_dev_write() did not return GMAC-OK. */
             unsigned tx_callback;     /* Transmission ready, buffer returned to driver. */
             unsigned tx_release_ok;   /* Buffer released. */
             unsigned tx_release_bad;  /* Buffer corruption. */

From 0c38c80f6e6e467d8e9399fd09d9d736a53deb92 Mon Sep 17 00:00:00 2001
From: GitHub Action <action@github.com>
Date: Thu, 3 Nov 2022 06:09:01 +0000
Subject: [PATCH 3/7] Uncrustify: triggered by comment.

---
 source/portable/NetworkInterface/DriverSAM/gmac_SAM.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
index eab7fc726e..17222dc8ac 100644
--- a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
+++ b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
@@ -1008,7 +1008,7 @@ void gmac_handler( gmac_device_t * p_gmac_dev )
 /*/ @cond 0 */
 /**INDENT-OFF**/
 #ifdef __cplusplus
-}
+    }
 #endif
 /**INDENT-ON**/
 /*/ @endcond */

From 62ec542e86a097ad1b6e3de7141aa7d9f0b1ffb4 Mon Sep 17 00:00:00 2001
From: Hein Tibosch <hein@htibosch.net>
Date: Fri, 4 Nov 2022 16:01:51 +0800
Subject: [PATCH 4/7] Increase NETWORK_BUFFER_SIZE in order to include the
 'ipBUFFER_PADDING' bytes

---
 .../DriverSAM/NetworkInterface.c                | 17 ++++++-----------
 .../NetworkInterface/DriverSAM/gmac_SAM.c       | 14 ++++++++++++--
 .../NetworkInterface/DriverSAM/gmac_SAM.h       | 11 +++++++----
 3 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c b/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c
index 7bbbc81425..3f72a30017 100644
--- a/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c
+++ b/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c
@@ -71,12 +71,6 @@
 #define EMAC_IF_ERR_EVENT    4UL
 #define EMAC_IF_ALL_EVENT    ( EMAC_IF_RX_EVENT | EMAC_IF_TX_EVENT | EMAC_IF_ERR_EVENT )
 
-/* 1536 bytes is more than needed, 1524 would be enough.
- * But 1536 is a multiple of 32, which gives a great alignment for
- * cached memories. */
-
-#define NETWORK_BUFFER_SIZE    1536
-
 #ifndef EMAC_MAX_BLOCK_TIME_MS
 
 /* The task 'prvEMACHandlerTask()' will wake-up every 100 ms, to see
@@ -518,9 +512,10 @@ BaseType_t xNetworkInterfaceOutput( NetworkBufferDescriptor_t * const pxDescript
 
     pxSendPacket = ( IPPacket_t * ) pxDescriptor->pucEthernetBuffer;
 
-    if( ulTransmitSize > NETWORK_BUFFER_SIZE )
+	/* 'GMAC_TX_UNITSIZE' is the netto size of a transmission buffer. */
+    if( ulTransmitSize > GMAC_TX_UNITSIZE )
     {
-        ulTransmitSize = NETWORK_BUFFER_SIZE;
+        ulTransmitSize = GMAC_TX_UNITSIZE;
     }
 
     /* A do{}while(0) loop is introduced to allow the use of multiple break
@@ -566,7 +561,7 @@ BaseType_t xNetworkInterfaceOutput( NetworkBufferDescriptor_t * const pxDescript
             }
         #endif
 
-        ulResult = gmac_dev_write( &gs_gmac_dev, ( void * ) pxDescriptor->pucEthernetBuffer, pxDescriptor->xDataLength );
+        ulResult = gmac_dev_write( &gs_gmac_dev, ( void * ) pxDescriptor->pucEthernetBuffer, ulTransmitSize );
 
         if( ulResult != GMAC_OK )
         {
@@ -773,7 +768,7 @@ static uint32_t prvEMACRxPoll( void )
          * descriptor then allocate one now. */
         if( ( pxNextNetworkBufferDescriptor == NULL ) && ( uxGetNumberOfFreeNetworkBuffers() > xMinDescriptorsToLeave ) )
         {
-            pxNextNetworkBufferDescriptor = pxGetNetworkBufferWithDescriptor( ipTOTAL_ETHERNET_FRAME_SIZE, xBlockTime );
+            pxNextNetworkBufferDescriptor = pxGetNetworkBufferWithDescriptor( GMAC_RX_UNITSIZE, xBlockTime );
         }
 
         if( pxNextNetworkBufferDescriptor != NULL )
@@ -789,7 +784,7 @@ static uint32_t prvEMACRxPoll( void )
         }
 
         /* Read the next packet from the hardware into pucUseBuffer. */
-        ulResult = gmac_dev_read( &gs_gmac_dev, pucUseBuffer, ipTOTAL_ETHERNET_FRAME_SIZE, &ulReceiveCount, &pucDMABuffer );
+        ulResult = gmac_dev_read( &gs_gmac_dev, pucUseBuffer, GMAC_RX_UNITSIZE, &ulReceiveCount, &pucDMABuffer );
 
         if( ( ulResult != GMAC_OK ) || ( ulReceiveCount == 0 ) )
         {
diff --git a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
index 17222dc8ac..5e15b2ddf1 100644
--- a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
+++ b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
@@ -120,8 +120,18 @@
  * @{
  */
 
-#define NETWORK_BUFFER_SIZE    1536
-
+/*
+ *     When BufferAllocation_1.c is used, the network buffer space
+ *     is declared statically as 'ucNetworkPackets[]'.
+ *     Like the DMA descriptors, this array is located in a non-cached area.
+ *     Here an example of the total size:
+ *
+ *         #define ipconfigNUM_NETWORK_BUFFER_DESCRIPTORS    24
+ *         #define GMAC_FRAME_LENTGH_MAX                     1536
+ *         Hidden space for back-pointer and IP-type         16
+ *
+ *     Total size: 24 * ( 1536 + 16 ) = 37248 bytes
+ */
 __attribute__( ( aligned( 32 ) ) )
 __attribute__( ( section( ".first_data" ) ) )
 uint8_t ucNetworkPackets[ ipconfigNUM_NETWORK_BUFFER_DESCRIPTORS * NETWORK_BUFFER_SIZE ];
diff --git a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h
index 414300b875..4b7def2928 100644
--- a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h
+++ b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h
@@ -96,12 +96,15 @@
 
 /** The MAC can support frame lengths up to 1536 bytes */
     #define GMAC_FRAME_LENTGH_MAX      1536
+    #define GMAC_RX_UNITSIZE           GMAC_FRAME_LENTGH_MAX /**< Maximum size for RX buffer  */
+    #define GMAC_TX_UNITSIZE           GMAC_FRAME_LENTGH_MAX /**< Maximum size for TX buffer  */
 
-/*#define GMAC_RX_UNITSIZE            128     / **< Fixed size for RX buffer  * / */
-    #define GMAC_RX_UNITSIZE           1536 /**< Fixed size for RX buffer  */
+    /* A network buffer starts with 10 hidden bytes (ipBUFFER_PADDING)
+     * in which a pointer is stored. Round up this extra size to a multiple of 16,
+     * in order to get well-aligned buffers. */
 
-/*#define GMAC_TX_UNITSIZE            1518    / **< Size for ETH frame length * / */
-    #define GMAC_TX_UNITSIZE           1536 /**< Size for ETH frame length */
+    #define BUFFER_PADDING             ( ( ipBUFFER_PADDING + 16U ) & ~0x0FU )
+    #define NETWORK_BUFFER_SIZE        ( GMAC_FRAME_LENTGH_MAX + BUFFER_PADDING )
 
 /** GMAC clock speed */
     #define GMAC_MCK_SPEED_240MHZ      ( 240 * 1000 * 1000 )

From 4d052605b4ad45b9681990a9eae7098c3b747a4f Mon Sep 17 00:00:00 2001
From: Hein Tibosch <hein@htibosch.net>
Date: Fri, 4 Nov 2022 16:38:11 +0800
Subject: [PATCH 5/7] ICMP checksum calculated manually

---
 .../DriverSAM/NetworkInterface.c              | 27 +++++++----
 .../NetworkInterface/DriverSAM/gmac_SAM.c     | 19 +++-----
 .../NetworkInterface/DriverSAM/gmac_SAM.h     | 45 ++++++++++---------
 3 files changed, 49 insertions(+), 42 deletions(-)

diff --git a/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c b/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c
index 3f72a30017..7974b72a49 100644
--- a/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c
+++ b/source/portable/NetworkInterface/DriverSAM/NetworkInterface.c
@@ -512,7 +512,7 @@ BaseType_t xNetworkInterfaceOutput( NetworkBufferDescriptor_t * const pxDescript
 
     pxSendPacket = ( IPPacket_t * ) pxDescriptor->pucEthernetBuffer;
 
-	/* 'GMAC_TX_UNITSIZE' is the netto size of a transmission buffer. */
+    /* 'GMAC_TX_UNITSIZE' is the netto size of a transmission buffer. */
     if( ulTransmitSize > GMAC_TX_UNITSIZE )
     {
         ulTransmitSize = GMAC_TX_UNITSIZE;
@@ -737,17 +737,26 @@ void vGMACGenerateChecksum( uint8_t * pucBuffer,
 {
     ProtocolPacket_t * xProtPacket = ( ProtocolPacket_t * ) pucBuffer;
 
-    if( xProtPacket->xTCPPacket.xEthernetHeader.usFrameType == ipIPv4_FRAME_TYPE )
+    /* The SAM4E has problems offloading checksums for transmission.
+     * The SAME70 does not set the CRC for ICMP packets (ping). */
+
+    if( xProtPacket->xICMPPacket.xEthernetHeader.usFrameType == ipIPv4_FRAME_TYPE )
     {
-        IPHeader_t * pxIPHeader = &( xProtPacket->xTCPPacket.xIPHeader );
+        #if ( SAME70 != 0 )
+            if( ( xProtPacket->xICMPPacket.xIPHeader.ucProtocol != ipPROTOCOL_UDP ) &&
+                ( xProtPacket->xICMPPacket.xIPHeader.ucProtocol != ipPROTOCOL_TCP ) )
+        #endif
+        {
+            IPHeader_t * pxIPHeader = &( xProtPacket->xTCPPacket.xIPHeader );
 
-        /* Calculate the IP header checksum. */
-        pxIPHeader->usHeaderChecksum = 0x00;
-        pxIPHeader->usHeaderChecksum = usGenerateChecksum( 0U, ( uint8_t * ) &( pxIPHeader->ucVersionHeaderLength ), ipSIZE_OF_IPv4_HEADER );
-        pxIPHeader->usHeaderChecksum = ~FreeRTOS_htons( pxIPHeader->usHeaderChecksum );
+            /* Calculate the IP header checksum. */
+            pxIPHeader->usHeaderChecksum = 0x00;
+            pxIPHeader->usHeaderChecksum = usGenerateChecksum( 0U, ( uint8_t * ) &( pxIPHeader->ucVersionHeaderLength ), ipSIZE_OF_IPv4_HEADER );
+            pxIPHeader->usHeaderChecksum = ~FreeRTOS_htons( pxIPHeader->usHeaderChecksum );
 
-        /* Calculate the TCP checksum for an outgoing packet. */
-        usGenerateProtocolChecksum( pucBuffer, uxLength, pdTRUE );
+            /* Calculate the TCP checksum for an outgoing packet. */
+            usGenerateProtocolChecksum( pucBuffer, uxLength, pdTRUE );
+        }
     }
 }
 /*-----------------------------------------------------------*/
diff --git a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
index 5e15b2ddf1..e9de1ab6a0 100644
--- a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
+++ b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
@@ -698,11 +698,6 @@ uint32_t gmac_dev_read( gmac_device_t * p_gmac_dev,
     return GMAC_OK;
 }
 
-#if ( SAME70 == 0 )
-    extern void vGMACGenerateChecksum( uint8_t * apBuffer,
-                                       size_t uxLength );
-#endif
-
 /**
  * \brief Send ulLength bytes from pcFrom. This copies the buffer to one of the
  * GMAC Tx buffers, and then indicates to the GMAC that the buffer is ready.
@@ -759,13 +754,11 @@ uint32_t gmac_dev_write( gmac_device_t * p_gmac_dev,
                 memcpy( ( void * ) p_tx_td->addr, p_buffer, ul_size );
             }
         #endif /* ipconfigZERO_COPY_TX_DRIVER */
-        #if ( SAME70 == 0 )
-            {
-                #warning Is this a SAM4E?
-                /* Needs to be called for SAM4E series only. */
-                vGMACGenerateChecksum( ( uint8_t * ) p_tx_td->addr, ( size_t ) ul_size );
-            }
-        #endif
+        {
+            #warning Is this a SAM4E?
+            /* Needs to be called for SAM4E series only. */
+            vGMACGenerateChecksum( ( uint8_t * ) p_tx_td->addr, ( size_t ) ul_size );
+        }
     }
 
     /* Update transmit descriptor status */
@@ -1018,7 +1011,7 @@ void gmac_handler( gmac_device_t * p_gmac_dev )
 /*/ @cond 0 */
 /**INDENT-OFF**/
 #ifdef __cplusplus
-    }
+}
 #endif
 /**INDENT-ON**/
 /*/ @endcond */
diff --git a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h
index 4b7def2928..d59965f0d9 100644
--- a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h
+++ b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.h
@@ -99,42 +99,42 @@
     #define GMAC_RX_UNITSIZE           GMAC_FRAME_LENTGH_MAX /**< Maximum size for RX buffer  */
     #define GMAC_TX_UNITSIZE           GMAC_FRAME_LENTGH_MAX /**< Maximum size for TX buffer  */
 
-    /* A network buffer starts with 10 hidden bytes (ipBUFFER_PADDING)
-     * in which a pointer is stored. Round up this extra size to a multiple of 16,
-     * in order to get well-aligned buffers. */
+/* A network buffer starts with 10 hidden bytes (ipBUFFER_PADDING)
+ * in which a pointer is stored. Round up this extra size to a multiple of 16,
+ * in order to get well-aligned buffers. */
 
-    #define BUFFER_PADDING             ( ( ipBUFFER_PADDING + 16U ) & ~0x0FU )
-    #define NETWORK_BUFFER_SIZE        ( GMAC_FRAME_LENTGH_MAX + BUFFER_PADDING )
+    #define BUFFER_PADDING           ( ( ipBUFFER_PADDING + 16U ) & ~0x0FU )
+    #define NETWORK_BUFFER_SIZE      ( GMAC_FRAME_LENTGH_MAX + BUFFER_PADDING )
 
 /** GMAC clock speed */
-    #define GMAC_MCK_SPEED_240MHZ      ( 240 * 1000 * 1000 )
-    #define GMAC_MCK_SPEED_160MHZ      ( 160 * 1000 * 1000 )
-    #define GMAC_MCK_SPEED_120MHZ      ( 120 * 1000 * 1000 )
-    #define GMAC_MCK_SPEED_80MHZ       ( 80 * 1000 * 1000 )
-    #define GMAC_MCK_SPEED_40MHZ       ( 40 * 1000 * 1000 )
-    #define GMAC_MCK_SPEED_20MHZ       ( 20 * 1000 * 1000 )
+    #define GMAC_MCK_SPEED_240MHZ    ( 240 * 1000 * 1000 )
+    #define GMAC_MCK_SPEED_160MHZ    ( 160 * 1000 * 1000 )
+    #define GMAC_MCK_SPEED_120MHZ    ( 120 * 1000 * 1000 )
+    #define GMAC_MCK_SPEED_80MHZ     ( 80 * 1000 * 1000 )
+    #define GMAC_MCK_SPEED_40MHZ     ( 40 * 1000 * 1000 )
+    #define GMAC_MCK_SPEED_20MHZ     ( 20 * 1000 * 1000 )
 
 /** GMAC maintain code default value*/
-    #define GMAC_MAN_CODE_VALUE        ( 10 )
+    #define GMAC_MAN_CODE_VALUE      ( 10 )
 
 /** GMAC maintain start of frame default value*/
-    #define GMAC_MAN_SOF_VALUE         ( 1 )
+    #define GMAC_MAN_SOF_VALUE       ( 1 )
 
 /** GMAC maintain read/write*/
-    #define GMAC_MAN_RW_TYPE           ( 2 )
+    #define GMAC_MAN_RW_TYPE         ( 2 )
 
 /** GMAC maintain read only*/
-    #define GMAC_MAN_READ_ONLY         ( 1 )
+    #define GMAC_MAN_READ_ONLY       ( 1 )
 
 /** GMAC address length */
-    #define GMAC_ADDR_LENGTH           ( 6 )
+    #define GMAC_ADDR_LENGTH         ( 6 )
 
 
-    #define GMAC_DUPLEX_HALF           0
-    #define GMAC_DUPLEX_FULL           1
+    #define GMAC_DUPLEX_HALF         0
+    #define GMAC_DUPLEX_FULL         1
 
-    #define GMAC_SPEED_10M             0
-    #define GMAC_SPEED_100M            1
+    #define GMAC_SPEED_10M           0
+    #define GMAC_SPEED_100M          1
 
 /**
  * \brief Return codes for GMAC APIs.
@@ -1539,6 +1539,11 @@
 
     void gmac_reset_tx_mem( gmac_device_t * p_dev );
 
+/* The SAM4E has problems offloading checksums for transmission.
+ * The SAME70 does not set the CRC for ICMP packets (ping). */
+    extern void vGMACGenerateChecksum( uint8_t * apBuffer,
+                                       size_t uxLength );
+
 /*/ @cond 0 */
 /**INDENT-OFF**/
     #ifdef __cplusplus

From 6974fcd89e8a4af214a8f94d69f5083e5d8b2232 Mon Sep 17 00:00:00 2001
From: GitHub Action <action@github.com>
Date: Mon, 7 Nov 2022 06:40:47 +0000
Subject: [PATCH 6/7] Uncrustify: triggered by comment.

---
 source/portable/NetworkInterface/DriverSAM/gmac_SAM.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
index fcfb13727a..5c19b5191e 100644
--- a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
+++ b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
@@ -1010,7 +1010,7 @@ void gmac_handler( gmac_device_t * p_gmac_dev )
 /*/ @cond 0 */
 /**INDENT-OFF**/
 #ifdef __cplusplus
-}
+    }
 #endif
 /**INDENT-ON**/
 /*/ @endcond */

From 0b7d22302879dedf2c469a87dbcd3384482f1762 Mon Sep 17 00:00:00 2001
From: Aniruddha Kanhere <60444055+AniruddhaKanhere@users.noreply.github.com>
Date: Mon, 7 Nov 2022 01:12:18 -0800
Subject: [PATCH 7/7] Update gmac_SAM.c

---
 source/portable/NetworkInterface/DriverSAM/gmac_SAM.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
index 5c19b5191e..e864e1be72 100644
--- a/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
+++ b/source/portable/NetworkInterface/DriverSAM/gmac_SAM.c
@@ -111,8 +111,8 @@
  * See \ref gmac_quickstart.
  *
  * Driver for the GMAC (Ethernet Media Access Controller).
- * This file contains basic functions for the GMAC, with support for all modes, settings
- * and clock speeds.
+ * This file contains basic functions for the GMAC, with support for all modes,
+ * settings and clock speeds.
  *
  * \section dependencies Dependencies
  * This driver does not depend on other modules.