[IA64-SGI] altix: enable vgacon support

Altix patch to enable use of vgacon driver on that platform.  Depends on the
PCDP generalization patch discussed at:

	http://marc.theaimsgroup.com/?l=linux-ia64&m=111446235101939&w=2

Signed-off-by: Mark Maule <maule@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/configs/sn2_defconfig

@@ -99,7 +99,7 @@ CONFIG_ACPI_DEALLOCATE_IRQ=y
 # Firmware Drivers
 #
 CONFIG_EFI_VARS=y
-# CONFIG_EFI_PCDP is not set
+CONFIG_EFI_PCDP=y
 CONFIG_BINFMT_ELF=y
 # CONFIG_BINFMT_MISC is not set
 
@@ -650,7 +650,7 @@ CONFIG_MMTIMER=y
 #
 # Console display driver support
 #
-# CONFIG_VGA_CONSOLE is not set
+CONFIG_VGA_CONSOLE=y
 CONFIG_DUMMY_CONSOLE=y
 
 #

arch/ia64/sn/kernel/iomv.c

@@ -9,12 +9,16 @@
 #include <linux/module.h>
 #include <asm/io.h>
 #include <asm/delay.h>
+#include <asm/vga.h>
 #include <asm/sn/nodepda.h>
 #include <asm/sn/simulator.h>
 #include <asm/sn/pda.h>
 #include <asm/sn/sn_cpuid.h>
 #include <asm/sn/shub_mmr.h>
 
+#define IS_LEGACY_VGA_IOPORT(p) \
+	(((p) >= 0x3b0 && (p) <= 0x3bb) || ((p) >= 0x3c0 && (p) <= 0x3df))
+
 /**
  * sn_io_addr - convert an in/out port to an i/o address
  * @port: port to convert
@@ -26,6 +30,8 @@
 void *sn_io_addr(unsigned long port)
 {
 	if (!IS_RUNNING_ON_SIMULATOR()) {
+		if (IS_LEGACY_VGA_IOPORT(port))
+			port += vga_console_iobase;
 		/* On sn2, legacy I/O ports don't point at anything */
 		if (port < (64 * 1024))
 			return NULL;

arch/ia64/sn/kernel/setup.c

@@ -36,6 +36,7 @@
 #include <asm/machvec.h>
 #include <asm/system.h>
 #include <asm/processor.h>
+#include <asm/vga.h>
 #include <asm/sn/arch.h>
 #include <asm/sn/addrs.h>
 #include <asm/sn/pda.h>
@@ -273,14 +274,17 @@ void __init sn_setup(char **cmdline_p)
 
 	ia64_sn_plat_set_error_handling_features();
 
-	/*
-	 * If the generic code has enabled vga console support - lets
-	 * get rid of it again. This is a kludge for the fact that ACPI
-	 * currtently has no way of informing us if legacy VGA is available
-	 * or not.
-	 */
 #if defined(CONFIG_VT) && defined(CONFIG_VGA_CONSOLE)
-	if (conswitchp == &vga_con) {
+	/*
+	 * If there was a primary vga adapter identified through the
+	 * EFI PCDP table, make it the preferred console.  Otherwise
+	 * zero out conswitchp.
+	 */
+
+	if (vga_console_membase) {
+		/* usable vga ... make tty0 the preferred default console */
+		add_preferred_console("tty", 0, NULL);
+	} else {
 		printk(KERN_DEBUG "SGI: Disabling VGA console\n");
 #ifdef CONFIG_DUMMY_CONSOLE
 		conswitchp = &dummy_con;