Merge branch 'pm-cpufreq'

[linux.git] / Documentation / hwspinlock.txt

diff --git a/Documentation/hwspinlock.txt b/Documentation/hwspinlock.txt
index ed640a278185c91e0e9c7dc89dd6d93ad2a280ca..6f03713b70039020c82f6b12f8f323c2c0853c76 100644 (file)
--- a/Documentation/hwspinlock.txt
+++ b/Documentation/hwspinlock.txt
@@ -134,6 +134,39 @@ notably -ETIMEDOUT if the hwspinlock is still busy after timeout msecs).
 
 The function will never sleep.
 
 
 The function will never sleep.
 

+::
+
+  int hwspin_lock_timeout_raw(struct hwspinlock *hwlock, unsigned int timeout);
+
+Lock a previously-assigned hwspinlock with a timeout limit (specified in
+msecs). If the hwspinlock is already taken, the function will busy loop
+waiting for it to be released, but give up when the timeout elapses.
+
+Caution: User must protect the routine of getting hardware lock with mutex
+or spinlock to avoid dead-lock, that will let user can do some time-consuming
+or sleepable operations under the hardware lock.
+
+Returns 0 when successful and an appropriate error code otherwise (most
+notably -ETIMEDOUT if the hwspinlock is still busy after timeout msecs).
+
+The function will never sleep.
+
+::
+
+  int hwspin_lock_timeout_in_atomic(struct hwspinlock *hwlock, unsigned int to);
+
+Lock a previously-assigned hwspinlock with a timeout limit (specified in
+msecs). If the hwspinlock is already taken, the function will busy loop
+waiting for it to be released, but give up when the timeout elapses.
+
+This function shall be called only from an atomic context and the timeout
+value shall not exceed a few msecs.
+
+Returns 0 when successful and an appropriate error code otherwise (most
+notably -ETIMEDOUT if the hwspinlock is still busy after timeout msecs).
+
+The function will never sleep.
+

 ::
 
   int hwspin_trylock(struct hwspinlock *hwlock);
 ::
 
   int hwspin_trylock(struct hwspinlock *hwlock);


@@ -184,6 +217,34 @@ Returns 0 on success and an appropriate error code otherwise (most
 notably -EBUSY if the hwspinlock was already taken).
 The function will never sleep.
 
 notably -EBUSY if the hwspinlock was already taken).
 The function will never sleep.
 

+::
+
+  int hwspin_trylock_raw(struct hwspinlock *hwlock);
+
+Attempt to lock a previously-assigned hwspinlock, but immediately fail if
+it is already taken.
+
+Caution: User must protect the routine of getting hardware lock with mutex
+or spinlock to avoid dead-lock, that will let user can do some time-consuming
+or sleepable operations under the hardware lock.
+
+Returns 0 on success and an appropriate error code otherwise (most
+notably -EBUSY if the hwspinlock was already taken).
+The function will never sleep.
+
+::
+
+  int hwspin_trylock_in_atomic(struct hwspinlock *hwlock);
+
+Attempt to lock a previously-assigned hwspinlock, but immediately fail if
+it is already taken.
+
+This function shall be called only from an atomic context.
+
+Returns 0 on success and an appropriate error code otherwise (most
+notably -EBUSY if the hwspinlock was already taken).
+The function will never sleep.
+

 ::
 
   void hwspin_unlock(struct hwspinlock *hwlock);
 ::
 
   void hwspin_unlock(struct hwspinlock *hwlock);


@@ -220,6 +281,26 @@ Upon a successful return from this function, preemption is reenabled,
 and the state of the local interrupts is restored to the state saved at
 the given flags. This function will never sleep.
 
 and the state of the local interrupts is restored to the state saved at
 the given flags. This function will never sleep.
 

+::
+
+  void hwspin_unlock_raw(struct hwspinlock *hwlock);
+
+Unlock a previously-locked hwspinlock.
+
+The caller should **never** unlock an hwspinlock which is already unlocked.
+Doing so is considered a bug (there is no protection against this).
+This function will never sleep.
+
+::
+
+  void hwspin_unlock_in_atomic(struct hwspinlock *hwlock);
+
+Unlock a previously-locked hwspinlock.
+
+The caller should **never** unlock an hwspinlock which is already unlocked.
+Doing so is considered a bug (there is no protection against this).
+This function will never sleep.
+

 ::
 
   int hwspin_lock_get_id(struct hwspinlock *hwlock);
 ::
 
   int hwspin_lock_get_id(struct hwspinlock *hwlock);