firewire: core: add is_local sysfs device attribute

Making this information available in sysfs allows to differentiate
between controllers in the local and remote Linux PCs, and thus is
useful for servers that are started with udev rules.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index 4d460ef..7a05fd2 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -398,6 +398,14 @@
 	return ret;
 }
 
+static ssize_t is_local_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct fw_device *device = fw_device(dev);
+
+	return sprintf(buf, "%u\n", device->is_local);
+}
+
 static int units_sprintf(char *buf, const u32 *directory)
 {
 	struct fw_csr_iterator ci;
@@ -447,6 +455,7 @@
 static struct device_attribute fw_device_attributes[] = {
 	__ATTR_RO(config_rom),
 	__ATTR_RO(guid),
+	__ATTR_RO(is_local),
 	__ATTR_RO(units),
 	__ATTR_NULL,
 };