diff --git a/Documentation/ABI/testing/sysfs-devices-sun b/Documentation/ABI/testing/sysfs-devices-sun
new file mode 100644
index 000000000000..86be9848a77e
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-sun
@@ -0,0 +1,14 @@
+Whatt:		/sys/devices/.../sun
+Date:		October 2012
+Contact:	Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
+Description:
+		The file contains a Slot-unique ID which provided by the _SUN
+		method in the ACPI namespace. The value is written in Advanced
+		Configuration and Power Interface Specification as follows:
+
+		"The _SUN value is required to be unique among the slots of
+		the same type. It is also recommended that this number match
+		the slot number printed on the physical slot whenever possible."
+
+		So reading the sysfs file, we can identify a physical position
+		of the slot in the system.
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 9d43532d69b1..d0b38ab47ab5 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -283,11 +283,21 @@ static ssize_t description_show(struct device *dev,
 }
 static DEVICE_ATTR(description, 0444, description_show, NULL);
 
+static ssize_t
+acpi_device_sun_show(struct device *dev, struct device_attribute *attr,
+		     char *buf) {
+	struct acpi_device *acpi_dev = to_acpi_device(dev);
+
+	return sprintf(buf, "%lu\n", acpi_dev->pnp.sun);
+}
+static DEVICE_ATTR(sun, 0444, acpi_device_sun_show, NULL);
+
 static int acpi_device_setup_files(struct acpi_device *dev)
 {
 	struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
 	acpi_status status;
 	acpi_handle temp;
+	unsigned long long sun;
 	int result = 0;
 
 	/*
@@ -329,6 +339,16 @@ static int acpi_device_setup_files(struct acpi_device *dev)
 	if (dev->pnp.unique_id)
 		result = device_create_file(&dev->dev, &dev_attr_uid);
 
+	status = acpi_evaluate_integer(dev->handle, "_SUN", NULL, &sun);
+	if (ACPI_SUCCESS(status)) {
+		dev->pnp.sun = (unsigned long)sun;
+		result = device_create_file(&dev->dev, &dev_attr_sun);
+		if (result)
+			goto end;
+	} else {
+		dev->pnp.sun = (unsigned long)-1;
+	}
+
         /*
          * If device has _EJ0, 'eject' file is created that is used to trigger
          * hot-removal function from userland.
@@ -360,6 +380,10 @@ static void acpi_device_remove_files(struct acpi_device *dev)
 	if (ACPI_SUCCESS(status))
 		device_remove_file(&dev->dev, &dev_attr_eject);
 
+	status = acpi_get_handle(dev->handle, "_SUN", &temp);
+	if (ACPI_SUCCESS(status))
+		device_remove_file(&dev->dev, &dev_attr_sun);
+
 	if (dev->pnp.unique_id)
 		device_remove_file(&dev->dev, &dev_attr_uid);
 	if (dev->flags.bus_address)
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index e8b2877aea33..6f385e5909db 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -179,6 +179,7 @@ struct acpi_device_pnp {
 	acpi_device_name device_name;	/* Driver-determined */
 	acpi_device_class device_class;	/*        "          */
 	union acpi_object *str_obj;	/* unicode string for _STR method */
+	unsigned long sun;		/* _SUN */
 };
 
 #define acpi_device_bid(d)	((d)->pnp.bus_id)