[RFKILL]: Add support for hardware-only rfkill buttons

Buttons that work directly on hardware cannot support
the "user_claim" functionality. Add a flag to signal
this and return -EOPNOTSUPP in this case.
b43 is such a device.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 9 insertions, 1 deletions

diff --git a/include/linux/rfkill.h b/include/linux/rfkill.h
index 26fddea12c25..0ce5e0b52dbd 100644
--- a/include/linux/rfkill.h
+++ b/include/linux/rfkill.h
@@ -52,6 +52,8 @@ enum rfkill_state {
  * @type: Radio type which the button controls, the value stored
  *      here should be a value from enum rfkill_type.
  * @state: State of the switch (on/off).
+ * @user_claim_unsupported: Whether the hardware supports exclusive
+ *      RF-kill control by userspace. Set this before registering.
  * @user_claim: Set when the switch is controlled exlusively by userspace.
  * @mutex: Guards switch state transitions
  * @data: Pointer to the RF button drivers private data which will be
@@ -69,6 +71,7 @@ struct rfkill {
         enum rfkill_type type;
 
         enum rfkill_state state;
+        bool user_claim_unsupported;
         bool user_claim;
 
         struct mutex mutex;
diff --git a/net/rfkill/rfkill.c b/net/rfkill/rfkill.c
index a8c5e0b914e4..51d151c0e962 100644
--- a/net/rfkill/rfkill.c
+++ b/net/rfkill/rfkill.c
@@ -190,6 +190,10 @@ static ssize_t rfkill_claim_store(struct device *dev,
         if (error)
                 return error;
 
+        if (rfkill->user_claim_unsupported) {
+                error = -EOPNOTSUPP;
+                goto out_unlock;
+        }
         if (rfkill->user_claim != claim) {
                 if (!claim)
                         rfkill_toggle_radio(rfkill,
@@ -197,9 +201,10 @@ static ssize_t rfkill_claim_store(struct device *dev,
                 rfkill->user_claim = claim;
         }
 
+out_unlock:
         mutex_unlock(&rfkill_mutex);
 
-        return count;
+        return error ? error : count;
 }
 
 static struct device_attribute rfkill_dev_attrs[] = {