x86: Add early platform detection

Platforms like Moorestown require early setup and want to avoid the
call to reserve_ebda_region. The x86_init override is too late when
the MRST detection happens in setup_arch. Move the default i386
x86_init overrides and the call to reserve_ebda_region into a separate
function which is called as the default of a switch case depending on
the hardware_subarch id in boot params. This allows us to add a case
for MRST and let MRST have its own early setup function.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/include/asm/x86_init.h

@@ -2,6 +2,7 @@
 #define _ASM_X86_PLATFORM_H
 
 #include <asm/pgtable_types.h>
+#include <asm/bootparam.h>
 
 struct mpc_bus;
 struct mpc_cpu;
@@ -34,14 +35,12 @@ struct x86_init_mpparse {
  * @probe_roms:			probe BIOS roms
  * @reserve_resources:		reserve the standard resources for the
  *				platform
- * @reserve_ebda_region:	reserve the extended bios data area
  * @memory_setup:		platform specific memory setup
  *
  */
 struct x86_init_resources {
 	void (*probe_roms)(void);
 	void (*reserve_resources)(void);
-	void (*reserve_ebda_region)(void);
 	char *(*memory_setup)(void);
 };
 

arch/x86/kernel/head32.c

@@ -15,6 +15,17 @@
 #include <asm/trampoline.h>
 #include <asm/apic.h>
 #include <asm/io_apic.h>
+#include <asm/bios_ebda.h>
+
+static void __init i386_default_early_setup(void)
+{
+	/* Initilize 32bit specific setup functions */
+	x86_init.resources.probe_roms = probe_roms;
+	x86_init.resources.reserve_resources = i386_reserve_resources;
+	x86_init.mpparse.setup_ioapic_ids = setup_ioapic_ids_from_mpc;
+
+	reserve_ebda_region();
+}
 
 void __init i386_start_kernel(void)
 {
@@ -31,12 +42,13 @@ void __init i386_start_kernel(void)
 		reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");
 	}
 #endif
-	/* Initilize 32bit specific setup functions */
-	x86_init.resources.probe_roms = probe_roms;
-	x86_init.resources.reserve_resources = i386_reserve_resources;
-	x86_init.mpparse.setup_ioapic_ids = setup_ioapic_ids_from_mpc;
 
-	x86_init.resources.reserve_ebda_region();
+	/* Call the subarch specific early setup function */
+	switch (boot_params.hdr.hardware_subarch) {
+	default:
+		i386_default_early_setup();
+		break;
+	}
 
 	/*
 	 * At this point everything still needed from the boot loader

arch/x86/kernel/head64.c

@@ -24,6 +24,7 @@
 #include <asm/kdebug.h>
 #include <asm/e820.h>
 #include <asm/trampoline.h>
+#include <asm/bios_ebda.h>
 
 static void __init zap_identity_mappings(void)
 {
@@ -111,7 +112,7 @@ void __init x86_64_start_reservations(char *real_mode_data)
 	}
 #endif
 
-	x86_init.resources.reserve_ebda_region();
+	reserve_ebda_region();
 
 	/*
 	 * At this point everything still needed from the boot loader

arch/x86/kernel/x86_init.c

@@ -28,7 +28,6 @@ struct __initdata x86_init_ops x86_init = {
 	.resources = {
 		.probe_roms		= x86_init_noop,
 		.reserve_resources	= reserve_standard_io_resources,
-		.reserve_ebda_region	= reserve_ebda_region,
 		.memory_setup		= default_machine_specific_memory_setup,
 	},