+/*
+ * Handle sysfs file creation and removal here, before userspace is told that
+ * the device is added / removed from the system
+ */
+static int w1_bus_notify(struct notifier_block *nb, unsigned long action,
+ void *data)
+{
+ struct device *dev = data;
+ struct w1_slave *sl;
+ int err;
+
+ /*
+ * Only care about slave devices at the moment. Yes, we should use a
+ * separate "type" for this, but for now, look at the release function
+ * to know which type it is...
+ */
+ if (dev->release != w1_slave_release)
+ return 0;
+
+ sl = dev_to_w1_slave(dev);
+
+ switch (action) {
+ case BUS_NOTIFY_ADD_DEVICE:
+ /* Create our sysfs files before userspace is told about it */
+ /* Create "name" entry */
+ err = device_create_file(&sl->dev, &w1_slave_attr_name);
+ if (err < 0) {
+ dev_err(&sl->dev,
+ "sysfs file creation for [%s] failed. err=%d\n",
+ dev_name(&sl->dev), err);
+ return err;
+ }
+
+ /* Create "id" entry */
+ err = device_create_file(&sl->dev, &w1_slave_attr_id);
+ if (err < 0) {
+ dev_err(&sl->dev,
+ "sysfs file creation for [%s] failed. err=%d\n",
+ dev_name(&sl->dev), err);
+ return err;
+ }
+
+ /* if the family driver needs to initialize something... */
+ if (sl->family->fops && sl->family->fops->add_slave &&
+ ((err = sl->family->fops->add_slave(sl)) < 0)) {
+ dev_err(&sl->dev,
+ "sysfs file creation for [%s] failed. err=%d\n",
+ dev_name(&sl->dev), err);
+ return err;
+ }
+
+ break;
+ case BUS_NOTIFY_DEL_DEVICE:
+ /* Remove our sysfs files */
+ if (sl->family->fops && sl->family->fops->remove_slave)
+ sl->family->fops->remove_slave(sl);
+ device_remove_file(&sl->dev, &w1_slave_attr_id);
+ device_remove_file(&sl->dev, &w1_slave_attr_name);
+ break;
+ }
+ return 0;
+}
+
+static struct notifier_block w1_bus_nb = {
+ .notifier_call = w1_bus_notify,
+};
+