added code to support FEC networking

net/fecbd.c

@@ -0,0 +1,226 @@
+/*
+ * File:    fecbd.c
+ * Purpose: Provide a simple buffer management driver
+ *
+ * Notes:       
+ */
+#include "MCD_dma.h"
+#include "fecbd.h"
+#include "nbuf.h"
+#include "eth.h"
+#include "bas_printf.h"
+#include <stddef.h>
+
+/*
+ * This implements a simple static buffer descriptor
+ * ring for each channel and each direction
+ *
+ * FEC Buffer Descriptors need to be aligned to a 4-byte boundary.
+ * In order to accomplish this, data is over-allocated and manually
+ * aligned at runtime
+ * 
+ * Enough space is allocated for each of the two FEC channels to have 
+ * NRXBD Rx BDs and NTXBD Tx BDs
+ * 
+ */
+
+FECBD unaligned_bds[(2 * NRXBD) + (2 * NTXBD) + 1];
+
+/*
+ * These pointers are used to reference into the chunck of data set 
+ * aside for buffer descriptors
+ */
+FECBD *RxBD;
+FECBD *TxBD;
+
+/*
+ * Macros to easier access to the BD ring
+ */
+#define RxBD(ch,i)      RxBD[(ch * NRXBD) + i]
+#define TxBD(ch,i)      TxBD[(ch * NTXBD) + i]
+
+/* 
+ * Buffer descriptor indexes 
+ */
+static int iTxbd_new;
+static int iTxbd_old;
+static int iRxbd;
+
+/*
+ * Initialize the FEC Buffer Descriptor ring 
+ * Buffer Descriptor format is defined by the MCDAPI
+ *
+ * Parameters:
+ *  ch      FEC channel
+ */
+void fecbd_init(uint8_t ch)
+{
+    NBUF *nbuf;
+    int i;
+    
+    /* 
+     * Align Buffer Descriptors to 4-byte boundary 
+     */
+    RxBD = (FECBD *)(((int)unaligned_bds + 3) & 0xFFFFFFFC);
+    TxBD = (FECBD *)((int)RxBD + (sizeof(FECBD) * 2 * NRXBD));
+
+    /* 
+     * Initialize the Rx Buffer Descriptor ring 
+     */
+    for (i = 0; i < NRXBD; ++i)
+    {
+        /* Grab a network buffer from the free list */
+        nbuf = nbuf_alloc();
+		if (nbuf == NULL)
+		{
+			xprintf("%s: could not allocate network buffer\r\n", __FUNCTION__);
+			return;
+		}
+			
+        /* Initialize the BD */
+        RxBD(ch,i).status = RX_BD_E | RX_BD_INTERRUPT;
+        RxBD(ch,i).length = RX_BUF_SZ;
+        RxBD(ch,i).data =  nbuf->data;
+
+        /* Add the network buffer to the Rx queue */
+        nbuf_add(NBUF_RX_RING, nbuf);
+    }
+
+    /*
+     * Set the WRAP bit on the last one
+     */
+    RxBD(ch,i-1).status |= RX_BD_W;
+
+    /* 
+     * Initialize the Tx Buffer Descriptor ring 
+     */
+    for (i = 0; i < NTXBD; ++i)
+    {
+        TxBD(ch,i).status = TX_BD_INTERRUPT;
+        TxBD(ch,i).length = 0;
+        TxBD(ch,i).data = NULL;
+    }
+
+    /*
+     * Set the WRAP bit on the last one
+     */
+    TxBD(ch,i-1).status |= TX_BD_W;
+
+    /* 
+     * Initialize the buffer descriptor indexes 
+     */
+    iTxbd_new = iTxbd_old = iRxbd = 0;
+}
+
+void fecbd_dump(uint8_t ch)
+{
+    #ifdef DEBUG_PRINT
+    int i;
+
+    printf("\n------------ FEC%d BDs -----------\n",ch);
+    printf("RxBD Ring\n");
+    for (i=0; i<NRXBD; i++)
+    {
+        printf("%02d: BD Addr=0x%08x, Ctrl=0x%04x, Lgth=%04d, DataPtr=0x%08x\n",
+            i, &RxBD(ch,i), 
+            RxBD(ch,i).status, 
+            RxBD(ch,i).length, 
+            RxBD(ch,i).data);
+    }
+    printf("TxBD Ring\n");
+    for (i=0; i<NTXBD; i++)
+    {
+        printf("%02d: BD Addr=0x%08x, Ctrl=0x%04x, Lgth=%04d, DataPtr=0x%08x\n",
+            i, &TxBD(ch,i), 
+            TxBD(ch,i).status, 
+            TxBD(ch,i).length, 
+            TxBD(ch,i).data);
+    }
+    printf("--------------------------------\n\n");
+    #endif
+}
+
+/* 
+ * Return the address of the first buffer descriptor in the ring.
+ *
+ * Parameters:
+ *  ch          FEC channel
+ *  direction   Rx or Tx Macro
+ *
+ * Return Value:
+ *  The start address of the selected Buffer Descriptor ring
+ */
+uint32_t fecbd_get_start(uint8_t ch, uint8_t direction)
+{
+    switch (direction)
+    {
+        case Rx:
+            return (uint32_t)((int)RxBD + (ch * sizeof(FECBD) * NRXBD));
+        case Tx:
+        default:
+            return (uint32_t)((int)TxBD + (ch * sizeof(FECBD) * NTXBD));
+    }
+}
+
+FECBD *fecbd_rx_alloc(uint8_t ch)
+{
+    int i = iRxbd;
+
+    /* Check to see if the ring of BDs is full */
+    if (RxBD(ch,i).status & RX_BD_E)
+        return NULL;
+
+    /* Increment the circular index */
+    iRxbd = (uint8_t)((iRxbd + 1) % NRXBD);
+
+    return &RxBD(ch,i);
+}
+
+/*
+ * This function keeps track of the next available Tx BD in the ring
+ *
+ * Parameters:
+ *  ch  FEC channel
+ *
+ * Return Value:
+ *  Pointer to next available buffer descriptor.
+ *  NULL if the BD ring is full
+ */
+FECBD *fecbd_tx_alloc(uint8_t ch)
+{
+    int i = iTxbd_new;
+
+    /* Check to see if the ring of BDs is full */
+    if (TxBD(ch,i).status & TX_BD_R)
+        return NULL;
+
+    /* Increment the circular index */
+    iTxbd_new = (uint8_t)((iTxbd_new + 1) % NTXBD);
+
+    return &TxBD(ch,i);
+}
+
+/*
+ * This function keeps track of the Tx BDs that have already been
+ * processed by the FEC
+ *
+ * Parameters:
+ *  ch  FEC channel
+ *
+ * Return Value:
+ *  Pointer to the oldest buffer descriptor that has already been sent
+ *  by the FEC, NULL if the BD ring is empty
+ */
+FECBD *fecbd_tx_free(uint8_t ch)
+{
+    int i = iTxbd_old;
+
+    /* Check to see if the ring of BDs is empty */
+    if ((TxBD(ch,i).data == NULL) || (TxBD(ch,i).status & TX_BD_R))
+        return NULL;
+
+    /* Increment the circular index */
+    iTxbd_old = (uint8_t)((iTxbd_old + 1) % NTXBD);
+
+    return &TxBD(ch,i);
+}