[efi] Try various possible SNP receive filters

The behavior observed in the Apple EFI (1.10) RecieveFilters() call
is:

  - failure if any of the PROMISCUOUS or MULTICAST filters are
    included

  - success if only UNICAST is included, however the result is
    UNICAST|BROADCAST

  - success if only UNICAST and BROADCAST are included

  - if UNICAST, or UNICAST|BROADCAST are used, but the previous call
    tried (and failed) to set UNICAST|BROADCAST|MULTICAST, then the
    result is UNICAST|BROADCAST|MULTICAST

Work around this apparently broken SNP implementation by trying
RecieveFilterMask, then falling back to UNICAST|BROADCAST|MULTICAST,
then UNICAST|BROADCAST, and finally UNICAST.

Modified-by: Michael Brown <mcb30@ipxe.org>
Tested-by: Curtis Larsen <larsen@dixie.edu>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/efi/snpnet.c

 	snpnet_check_link ( netdev );
 }
 
+/**
+ * Set receive filters
+ *
+ * @v netdev		Network device
+ * @ret rc		Return status code
+ */
+static int snpnet_rx_filters ( struct net_device *netdev ) {
+	struct snp_nic *snp = netdev->priv;
+	UINT32 filters[] = {
+		snp->snp->Mode->ReceiveFilterMask,
+		( EFI_SIMPLE_NETWORK_RECEIVE_UNICAST |
+		  EFI_SIMPLE_NETWORK_RECEIVE_MULTICAST |
+		  EFI_SIMPLE_NETWORK_RECEIVE_BROADCAST ),
+		( EFI_SIMPLE_NETWORK_RECEIVE_UNICAST |
+		  EFI_SIMPLE_NETWORK_RECEIVE_BROADCAST ),
+		( EFI_SIMPLE_NETWORK_RECEIVE_UNICAST ),
+	};
+	unsigned int i;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Try possible receive filters in turn */
+	for ( i = 0; i < ( sizeof ( filters ) / sizeof ( filters[0] ) ); i++ ) {
+		efirc = snp->snp->ReceiveFilters ( snp->snp, filters[i],
+						   0, TRUE, 0, NULL );
+		if ( efirc == 0 )
+			return 0;
+		rc = -EEFI ( efirc );
+		DBGC ( snp, "SNP %s could not set receive filters %#02x (have "
+		       "%#02x): %s\n", netdev->name, filters[i],
+		       snp->snp->Mode->ReceiveFilterSetting, strerror ( rc ) );
+	}
+
+	return rc;
+}
+
 /**
  * Open network device
  *
 static int snpnet_open ( struct net_device *netdev ) {
 	struct snp_nic *snp = netdev->priv;
 	EFI_MAC_ADDRESS *mac = ( ( void * ) netdev->ll_addr );
-	UINT32 filters;
 	EFI_STATUS efirc;
 	int rc;
 
 	}
 
 	/* Set receive filters */
-	filters = ( EFI_SIMPLE_NETWORK_RECEIVE_UNICAST |
-		    EFI_SIMPLE_NETWORK_RECEIVE_MULTICAST |
-		    EFI_SIMPLE_NETWORK_RECEIVE_BROADCAST |
-		    EFI_SIMPLE_NETWORK_RECEIVE_PROMISCUOUS |
-		    EFI_SIMPLE_NETWORK_RECEIVE_PROMISCUOUS_MULTICAST );
-	if ( ( efirc = snp->snp->ReceiveFilters ( snp->snp, filters, 0, TRUE,
-						  0, NULL ) ) != 0 ) {
-		rc = -EEFI ( efirc );
-		DBGC ( snp, "SNP %s could not set receive filters: %s\n",
-		       netdev->name, strerror ( rc ) );
+	if ( ( rc = snpnet_rx_filters ( netdev ) ) != 0 ) {
 		/* Ignore error */
 	}