ACPI: thinkpad-acpi: export to sysfs the state of the radio slider switch

Some ThinkPad models, notably the T60 and X60, have a slider switch to
enable and disable the radios.  The switch has the capability of
force-disabling the radios in hardware on most models, and it is supposed
to affect all radios (WLAN, WWAN, BlueTooth).

Export the switch state as a sysfs attribute, on ThinkPads where it is
available.

Thanks to Henning Schild for asking for this feature, and for tracking down
the EC register that holds the radio switch state.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Henning Schild <henning@wh9.tu-dresden.de>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/Documentation/thinkpad-acpi.txt b/Documentation/thinkpad-acpi.txt
index 142a14fa1d91..fe26e50a2b15 100644
--- a/Documentation/thinkpad-acpi.txt
+++ b/Documentation/thinkpad-acpi.txt
@@ -227,6 +227,12 @@ sysfs notes:
                 supported hot keys, except those which are handled by
                 the firmware.  Echo it to hotkey_mask above, to use.
 
+        hotkey_radio_sw:
+                if the ThinkPad has a hardware radio switch, this
+                attribute will read 0 if the switch is in the "radios
+                disabled" postition, and 1 if the switch is in the
+                "radios enabled" position.
+
 
 Bluetooth
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