parisc: Autodetect default output device and set console= kernel parameter

Usually palo (the PA-RISC boot loader) will check at boot time if the
machine/firmware was configured to use the serial line (ttyS0, SERIAL_x)
or the graphical display (tty0, graph) as default output device and add
the correct "console=ttyS0" or "console=tty0" Linux kernel parameter to
the kernel command line when starting the Linux kernel.

But the kernel could also have been started via the HP-UX boot loader
or directly in qemu, in which cases the console parameter is missing.

This patch fixes this problem by adding the correct console= parameter
if it's missing in the current kernel command line.
Signed-off-by: Helge Deller <deller@gmx.de>

arch/parisc/kernel/setup.c

@@ -48,6 +48,7 @@ struct proc_dir_entry * proc_mckinley_root __read_mostly = NULL;
 void __init setup_cmdline(char **cmdline_p)
 {
 	extern unsigned int boot_args[];
+	char *p;
 
 	/* Collect stuff passed in from the boot loader */
 
@@ -59,6 +60,16 @@ void __init setup_cmdline(char **cmdline_p)
 		strscpy(boot_command_line, (char *)__va(boot_args[1]),
 			COMMAND_LINE_SIZE);
 
+	/* autodetect console type (if not done by palo yet) */
+	p = boot_command_line;
+	if (!str_has_prefix(p, "console=") && !strstr(p, " console=")) {
+		strlcat(p, " console=", COMMAND_LINE_SIZE);
+		if (PAGE0->mem_cons.cl_class == CL_DUPLEX)
+			strlcat(p, "ttyS0", COMMAND_LINE_SIZE);
+		else
+			strlcat(p, "tty0", COMMAND_LINE_SIZE);
+	}
+
 #ifdef CONFIG_BLK_DEV_INITRD
 		if (boot_args[2] != 0) /* did palo pass us a ramdisk? */
 		{