[netdrvr eepro100] add PIO config option

this trivial patch adds EEPRO100_PIO config option, which forces eepro100.c
driver to use pio instead of mmio. This option is necessary to support
onboard i82557 on sgi visual workstation.

drivers/net/Kconfig

@@ -1359,6 +1359,17 @@ config EEPRO100
 	  a module, say M here and read <file:Documentation/modules.txt> as
 	  well as <file:Documentation/networking/net-modules.txt>.
 
+
+config EEPRO100_PIO
+	bool "Use PIO instead of MMIO" if !X86_VISWS
+	depends on EEPRO100
+	default y if X86_VISWS
+	help
+	  This instructs the driver to use programmed I/O ports (PIO) instead
+	  of PCI shared memory (MMIO).  This can possibly solve some problems
+	  in case your mainboard has memory consistency issues.  If unsure,
+	  say N.
+
 config E100
 	tristate "EtherExpressPro/100 support (e100, Alternate Intel driver)"
 	depends on NET_PCI && PCI

drivers/net/eepro100.c

@@ -120,6 +120,11 @@ static int options[] = {-1, -1, -1, -1, -1, -1, -1, -1};
 #include <linux/ethtool.h>
 #include <linux/mii.h>
 
+/* enable PIO instead of MMIO, if CONFIG_EEPRO100_PIO is selected */
+#ifdef CONFIG_EEPRO100_PIO
+#define USE_IO 1
+#endif
+
 static int debug = -1;
 #define DEBUG_DEFAULT		(NETIF_MSG_DRV		| \
 				 NETIF_MSG_HW		| \