rfkill: export persistent attribute in sysfs

This information allows userspace to implement a hybrid policy where
it can store the rfkill soft-blocked state in platform non-volatile
storage if available, and if not then file-based storage can be used.

Some users prefer platform non-volatile storage because of the behaviour
when dual-booting multiple versions of Linux, or if the rfkill setting
is changed in the BIOS setting screens, or if the BIOS responds to
wireless-toggle hotkeys itself before the relevant platform driver has
been loaded.

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/include/linux/rfkill.h b/include/linux/rfkill.h
index dcac724340d8..e73e2429a1b1 100644
--- a/include/linux/rfkill.h
+++ b/include/linux/rfkill.h
@@ -259,8 +259,9 @@ bool rfkill_set_sw_state(struct rfkill *rfkill, bool blocked);
  * userspace) of their initial state.  It should only be used before
  * registration.
  *
- * In addition, it marks the device as "persistent".  Persistent devices
- * are expected to preserve preserve their own state when suspended.
+ * In addition, it marks the device as "persistent", an attribute which
+ * can be read by userspace.  Persistent devices are expected to preserve
+ * their own state when suspended.
  */
 void rfkill_init_sw_state(struct rfkill *rfkill, bool blocked);