GRETH: added support for non-snooping GRETH 10/100 systems

When data cache snooping is not present the cache needs
flushing, the SPARC LEON CPUs does not have to ability
to flush individual cache rows and flushing all cache is
expensive. Instead the LDA instruction is used to force
cache miss on individual loads during the IP-align copy
operation required anyway.

GRETH GBIT non-snooping systems are still unsupported,
since it use zero-copy (can deal with unaligned DMA).

Let the bsp.h select if the GRETH driver is supported.
Currently only the LEON2/LEON3 platforms BSPs builds the
driver.

Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>

1 files changed, 61 insertions, 7 deletions

diff --git a/c/src/libchip/network/greth.c b/c/src/libchip/network/greth.c
index aff4d0f896..df3c143278 100644
--- a/c/src/libchip/network/greth.c
+++ b/c/src/libchip/network/greth.c
@@ -12,10 +12,10 @@
  */
 
 #include <rtems.h>
-
-#define GRETH_SUPPORTED
 #include <bsp.h>
 
+#ifdef GRETH_SUPPORTED
+
 #include <inttypes.h>
 #include <errno.h>
 #include <rtems/bspIo.h>
@@ -57,6 +57,11 @@ extern rtems_isr_entry set_vector( rtems_isr_entry, rtems_vector_number, int );
 extern void ipalign(struct mbuf *m);
 #endif
 
+/* Used when reading from memory written by GRETH DMA unit */
+#ifndef GRETH_MEM_LOAD
+#define GRETH_MEM_LOAD(addr) (*(volatile unsigned int *)(addr))
+#endif
+
 /*
  * Number of OCs supported by this driver
  */
@@ -499,6 +504,45 @@ auto_neg_done:
     print_init_info(sc);
 }
 
+#ifdef CPU_U32_FIX
+
+/*
+ * Routine to align the received packet so that the ip header
+ * is on a 32-bit boundary. Necessary for cpu's that do not
+ * allow unaligned loads and stores and when the 32-bit DMA
+ * mode is used.
+ *
+ * Transfers are done on word basis to avoid possibly slow byte
+ * and half-word writes.
+ */
+
+void ipalign(struct mbuf *m)
+{
+  unsigned int *first, *last, data;
+  unsigned int tmp;
+
+  if ((((int) m->m_data) & 2) && (m->m_len)) {
+    last = (unsigned int *) ((((int) m->m_data) + m->m_len + 8) & ~3);
+    first = (unsigned int *) (((int) m->m_data) & ~3);
+    tmp = GRETH_MEM_LOAD(first);
+    tmp = tmp << 16;
+    first++;
+    do {
+      /* When snooping is not available the LDA instruction must be used
+       * to avoid the cache to return an illegal value.
+       * Load with forced cache miss
+       */
+      data = GRETH_MEM_LOAD(first);
+      *first = tmp | (data >> 16);
+      tmp = data << 16;
+      first++;
+    } while (first <= last);
+
+    m->m_data = (caddr_t)(((int) m->m_data) + 2);
+  }
+}
+#endif
+
 void
 greth_Daemon (void *arg)
 {
@@ -510,6 +554,7 @@ greth_Daemon (void *arg)
     rtems_event_set events;
     rtems_interrupt_level level;
     int first;
+    unsigned int tmp;
 
     for (;;)
       {
@@ -539,7 +584,7 @@ greth_Daemon (void *arg)
     /* Scan for Received packets */
 again:
     while (!((len_status =
-		    dp->rxdesc[dp->rx_ptr].ctrl) & GRETH_RXD_ENABLE))
+		    GRETH_MEM_LOAD(&dp->rxdesc[dp->rx_ptr].ctrl)) & GRETH_RXD_ENABLE))
 	    {
                     bad = 0;
                     if (len_status & GRETH_RXD_TOOLONG)
@@ -583,10 +628,18 @@ again:
                                     len - sizeof (struct ether_header);
 
                             eh = mtod (m, struct ether_header *);
+
                             m->m_data += sizeof (struct ether_header);
 #ifdef CPU_U32_FIX
-                            if(!(dp->gbit_mac))
+                            if(!dp->gbit_mac) {
+                                    /* OVERRIDE CACHED ETHERNET HEADER FOR NON-SNOOPING SYSTEMS */
+                                    tmp = GRETH_MEM_LOAD((uintptr_t)eh);
+                                    tmp = GRETH_MEM_LOAD(4+(uintptr_t)eh);
+                                    tmp = GRETH_MEM_LOAD(8+(uintptr_t)eh);
+                                    tmp = GRETH_MEM_LOAD(12+(uintptr_t)eh);
+
                                     ipalign(m);	/* Align packet on 32-bit boundary */
+                            }
 #endif
 
                             ether_input (ifp, eh, m);
@@ -641,7 +694,7 @@ sendpacket (struct ifnet *ifp, struct mbuf *m)
     /*
      * Is there a free descriptor available?
      */
-    if ( dp->txdesc[dp->tx_ptr].ctrl & GRETH_TXD_ENABLE ){
+    if (GRETH_MEM_LOAD(&dp->txdesc[dp->tx_ptr].ctrl) & GRETH_TXD_ENABLE){
             /* No. */
             inside = 0;
             return 1;
@@ -651,7 +704,7 @@ sendpacket (struct ifnet *ifp, struct mbuf *m)
     n = m;
 
     len = 0;
-    temp = (unsigned char *) dp->txdesc[dp->tx_ptr].addr;
+    temp = (unsigned char *) GRETH_MEM_LOAD(&dp->txdesc[dp->tx_ptr].addr);
 #ifdef GRETH_DEBUG
     printf("TXD: 0x%08x : BUF: 0x%08x\n", (int) m->m_data, (int) temp);
 #endif
@@ -814,7 +867,7 @@ int greth_process_tx_gbit(struct greth_softc *sc)
      */
     for (;;){
         /* Reap Sent packets */
-        while((sc->tx_cnt > 0) && !(sc->txdesc[sc->tx_dptr].ctrl) && !(sc->txdesc[sc->tx_dptr].ctrl & GRETH_TXD_ENABLE)) {
+        while((sc->tx_cnt > 0) && !(GRETH_MEM_LOAD(&sc->txdesc[sc->tx_dptr].ctrl) & GRETH_TXD_ENABLE)) {
             m_free(sc->txmbuf[sc->tx_dptr]);
             sc->tx_dptr = (sc->tx_dptr + 1) % sc->txbufs;
             sc->tx_cnt--;
@@ -1146,3 +1199,4 @@ rtems_greth_driver_attach (struct rtems_bsdnet_ifconfig *config,
     return 1;
 };
 
+#endif