x86/platform/uv: Add return code to UV BIOS Init function

Add a return code to the UV BIOS init function that indicates the
successful initialization of the kernel/BIOS callback interface.

Signed-off-by: Mike Travis <[e-mail]>
Reviewed-by: Steve Wahl <[e-mail]>
Reviewed-by: Dimitri Sivanich <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: H. Peter Anvin <[e-mail]>
Cc: Hedi Berriche <[e-mail]>
Cc: Justin Ernst <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Russ Anderson <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/include/asm/uv/bios.h

···
 extern s64 uv_bios_reserved_page_pa(u64, u64 *, u64 *, u64 *);
 extern int uv_bios_set_legacy_vga_target(bool decode, int domain, int bus);
 
-extern void uv_bios_init(void);
+extern int uv_bios_init(void);
 
 extern unsigned long sn_rtc_cycles_per_second;
 extern int uv_type;

arch/x86/platform/uv/bios_uv.c

···
 }
 EXPORT_SYMBOL_GPL(uv_bios_set_legacy_vga_target);
 
-void uv_bios_init(void)
+int uv_bios_init(void)
 {
 	uv_systab = NULL;
 	if ((uv_systab_phys == EFI_INVALID_TABLE_ADDR) ||
 	    !uv_systab_phys || efi_runtime_disabled()) {
 		pr_crit("UV: UVsystab: missing\n");
-		return;
+		return -EEXIST;
 	}
 
 	uv_systab = ioremap(uv_systab_phys, sizeof(struct uv_systab));
 	if (!uv_systab || strncmp(uv_systab->signature, UV_SYSTAB_SIG, 4)) {
 		pr_err("UV: UVsystab: bad signature!\n");
 		iounmap(uv_systab);
-		return;
+		return -EINVAL;
 	}
 
 	/* Starting with UV4 the UV systab size is variable */
···
 		uv_systab = ioremap(uv_systab_phys, size);
 		if (!uv_systab) {
 			pr_err("UV: UVsystab: ioremap(%d) failed!\n", size);
-			return;
+			return -EFAULT;
 		}
 	}
 	pr_info("UV: UVsystab: Revision:%x\n", uv_systab->revision);
+	return 0;
 }