acpi: Introduce acpi_arch_get_root_pointer() for getting rsdp address

Add an architecture specific function to get the address of the RSDP
table. Per default it will just return 0 indicating falling back to
the current mechanism.

Signed-off-by: Juergen Gross <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Eric Biederman <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

Author: jgross1

drivers/acpi/osl.c

@@ -189,12 +189,15 @@ early_param("acpi_rsdp", setup_acpi_rsdp);
 
 acpi_physical_address __init acpi_os_get_root_pointer(void)
 {
-	acpi_physical_address pa = 0;
+	acpi_physical_address pa;
 
 #ifdef CONFIG_KEXEC
 	if (acpi_rsdp)
 		return acpi_rsdp;
 #endif
+	pa = acpi_arch_get_root_pointer();
+	if (pa)
+		return pa;
 
 	if (efi_enabled(EFI_CONFIG_TABLES)) {
 		if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)

include/linux/acpi.h

@@ -623,6 +623,13 @@ bool acpi_gtdt_c3stop(int type);
 int acpi_arch_timer_mem_init(struct arch_timer_mem *timer_mem, int *timer_count);
 #endif
 
+#ifndef ACPI_HAVE_ARCH_GET_ROOT_POINTER
+static inline u64 acpi_arch_get_root_pointer(void)
+{
+	return 0;
+}
+#endif
+
 #else	/* !CONFIG_ACPI */
 
 #define acpi_disabled 1