[IA64] Enable early console for Ski simulator

This patch cleans up the `enable early console for SKI' patch
(471e7a44848f467c9b83adc3463d019d2fa8817f), and
1. potentially allows the gensparse_defconfig to work again.
   (there are other problems running a generic kernel on Ski)
2. fixes the `console registered twice' problem.
3. Cleans up the code by moving the `extern hpsim_cons' declaration to
   a new asm/hpsim.h file.

Thanks to Jes for comments.

Signed-off-by: Peter Chubb <peterc@gelato.unsw.edu.au>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/hp/sim/hpsim_console.c

@@ -21,6 +21,7 @@
 #include <asm/machvec.h>
 #include <asm/pgtable.h>
 #include <asm/sal.h>
+#include <asm/hpsim.h>
 
 #include "hpsim_ssc.h"
 
@@ -28,7 +29,7 @@ static int simcons_init (struct console *, char *);
 static void simcons_write (struct console *, const char *, unsigned);
 static struct tty_driver *simcons_console_device (struct console *, int *);
 
-struct console hpsim_cons = {
+static struct console hpsim_cons = {
 	.name =		"simcons",
 	.write =	simcons_write,
 	.device =	simcons_console_device,
@@ -62,3 +63,15 @@ static struct tty_driver *simcons_console_device (struct console *c, int *index)
 	*index = c->index;
 	return hp_simserial_driver;
 }
+
+int simcons_register(void)
+{
+	if (!ia64_platform_is("hpsim"))
+		return 1;
+
+	if (hpsim_cons.flags & CON_ENABLED)
+		return 1;
+
+	register_console(&hpsim_cons);
+	return 0;
+}

arch/ia64/hp/sim/hpsim_setup.c

@@ -21,6 +21,7 @@
 #include <asm/machvec.h>
 #include <asm/pgtable.h>
 #include <asm/sal.h>
+#include <asm/hpsim.h>
 
 #include "hpsim_ssc.h"
 
@@ -41,11 +42,5 @@ hpsim_setup (char **cmdline_p)
 {
 	ROOT_DEV = Root_SDA1;		/* default to first SCSI drive */
 
-#ifdef CONFIG_HP_SIMSERIAL_CONSOLE
-	{
-		extern struct console hpsim_cons;
-		if (ia64_platform_is("hpsim"))
-			register_console(&hpsim_cons);
-	}
-#endif
+	simcons_register();
 }

arch/ia64/kernel/setup.c

@@ -60,6 +60,7 @@
 #include <asm/smp.h>
 #include <asm/system.h>
 #include <asm/unistd.h>
+#include <asm/hpsim.h>
 
 #if defined(CONFIG_SMP) && (IA64_CPU_SIZE > PAGE_SIZE)
 # error "struct cpuinfo_ia64 too big!"
@@ -389,13 +390,8 @@ early_console_setup (char *cmdline)
 	if (!efi_setup_pcdp_console(cmdline))
 		earlycons++;
 #endif
-#ifdef CONFIG_HP_SIMSERIAL_CONSOLE
-	{
-		extern struct console hpsim_cons;
-		register_console(&hpsim_cons);
+	if (!simcons_register())
 		earlycons++;
-	}
-#endif
 
 	return (earlycons) ? 0 : -1;
 }

include/asm-ia64/hpsim.h

@@ -0,0 +1,10 @@
+#ifndef _ASMIA64_HPSIM_H
+#define _ASMIA64_HPSIM_H
+
+#ifndef CONFIG_HP_SIMSERIAL_CONSOLE
+static inline int simcons_register(void) { return 1; }
+#else
+int simcons_register(void);
+#endif
+
+#endif