add to dahdi_device a "hardware_id" attribute as an alternative to "location"

- The "hardware_id" does not change with device location (e.g: when a PCI
  card is moved from one slot to another).
- Not all devices have this attribute. It is legal for it to be NULL (that
  is the default for all low-level drivers that do not set it explicitly).
- When "hardware_id" is NULL, the sysfs attribute value is "\n"

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/dahdi/dahdi-sysfs.c b/drivers/dahdi/dahdi-sysfs.c
index 161a1d9..0523ed4 100644
--- a/drivers/dahdi/dahdi-sysfs.c
+++ b/drivers/dahdi/dahdi-sysfs.c
@@ -484,6 +484,16 @@ dahdi_device_location_show(struct device *dev,
 }
 
 static ssize_t
+dahdi_device_hardware_id_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct dahdi_device *ddev = to_ddev(dev);
+
+	return sprintf(buf, "%s\n",
+		(ddev->hardware_id) ? ddev->hardware_id : "");
+}
+
+static ssize_t
 dahdi_device_auto_register(struct device *dev, struct device_attribute *attr,
 			   const char *buf, size_t count)
 {
@@ -524,6 +534,7 @@ static struct device_attribute dahdi_device_attrs[] = {
 	__ATTR(type, S_IRUGO, dahdi_device_type_show, NULL),
 	__ATTR(span_count, S_IRUGO, dahdi_device_span_count_show, NULL),
 	__ATTR(location, S_IRUGO, dahdi_device_location_show, NULL),
+	__ATTR(hardware_id, S_IRUGO, dahdi_device_hardware_id_show, NULL),
 	__ATTR(auto_register, S_IWUSR, NULL, dahdi_device_auto_register),
 	__ATTR(register_span, S_IWUSR, NULL, dahdi_device_register_span),
 	__ATTR_NULL,