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, 2 insertions, 0 deletions

diff --git a/Documentation/rfkill.txt b/Documentation/rfkill.txt
index c8acd8659e91..b4860509c319 100644
--- a/Documentation/rfkill.txt
+++ b/Documentation/rfkill.txt
@@ -111,6 +111,8 @@ following attributes:
 
         name: Name assigned by driver to this key (interface or driver name).
         type: Driver type string ("wlan", "bluetooth", etc).
+        persistent: Whether the soft blocked state is initialised from
+                    non-volatile storage at startup.
         state: Current state of the transmitter
                 0: RFKILL_STATE_SOFT_BLOCKED
                         transmitter is turned off by software