diff --git a/drivers/acpi/acpica/hwregs.c b/drivers/acpi/acpica/hwregs.c
index de74a4c25085..acb417b58bbb 100644
--- a/drivers/acpi/acpica/hwregs.c
+++ b/drivers/acpi/acpica/hwregs.c
@@ -107,7 +107,7 @@ acpi_hw_get_access_bit_width(u64 address,
 	    ACPI_IS_ALIGNED(reg->bit_width, 8)) {
 		access_bit_width = reg->bit_width;
 	} else if (reg->access_width) {
-		access_bit_width = (1 << (reg->access_width + 2));
+		access_bit_width = ACPI_ACCESS_BIT_WIDTH(reg->access_width);
 	} else {
 		access_bit_width =
 		    ACPI_ROUND_UP_POWER_OF_TWO_8(reg->bit_offset +
diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
index 4ac3e06b41d8..1230f969256b 100644
--- a/drivers/acpi/spcr.c
+++ b/drivers/acpi/spcr.c
@@ -95,16 +95,17 @@ int __init parse_spcr(bool earlycon)
 	}
 
 	if (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
-		switch (table->serial_port.access_width) {
+		switch (ACPI_ACCESS_BIT_WIDTH((
+			table->serial_port.access_width))) {
 		default:
 			pr_err("Unexpected SPCR Access Width.  Defaulting to byte size\n");
-		case ACPI_ACCESS_SIZE_BYTE:
+		case 8:
 			iotype = "mmio";
 			break;
-		case ACPI_ACCESS_SIZE_WORD:
+		case 16:
 			iotype = "mmio16";
 			break;
-		case ACPI_ACCESS_SIZE_DWORD:
+		case 32:
 			iotype = "mmio32";
 			break;
 		}
diff --git a/include/acpi/acrestyp.h b/include/acpi/acrestyp.h
index 4f7f39a02820..343dbdcef20c 100644
--- a/include/acpi/acrestyp.h
+++ b/include/acpi/acrestyp.h
@@ -377,13 +377,6 @@ struct acpi_resource_generic_register {
 	u64 address;
 };
 
-/* Generic Address Space Access Sizes */
-#define ACPI_ACCESS_SIZE_UNDEFINED		0
-#define ACPI_ACCESS_SIZE_BYTE			1
-#define ACPI_ACCESS_SIZE_WORD			2
-#define ACPI_ACCESS_SIZE_DWORD			3
-#define ACPI_ACCESS_SIZE_QWORD			4
-
 struct acpi_resource_gpio {
 	u8 revision_id;
 	u8 connection_type;
diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
index 2fcbaec8b368..0260be595d40 100644
--- a/include/acpi/actypes.h
+++ b/include/acpi/actypes.h
@@ -554,6 +554,13 @@ typedef u64 acpi_integer;
 #define ACPI_VALIDATE_RSDP_SIG(a)       (!strncmp (ACPI_CAST_PTR (char, (a)), ACPI_SIG_RSDP, 8))
 #define ACPI_MAKE_RSDP_SIG(dest)        (memcpy (ACPI_CAST_PTR (char, (dest)), ACPI_SIG_RSDP, 8))
 
+/*
+ * Algorithm to obtain access bit width.
+ * Can be used with access_width of struct acpi_generic_address and access_size of
+ * struct acpi_resource_generic_register.
+ */
+#define ACPI_ACCESS_BIT_WIDTH(size)     (1 << ((size) + 2))
+
 /*******************************************************************************
  *
  * Miscellaneous constants