diff options
author | Fabien Dessenne <fabien.dessenne@st.com> | 2019-03-07 16:58:23 +0100 |
---|---|---|
committer | Bjorn Andersson <bjorn.andersson@linaro.org> | 2019-06-29 21:08:14 -0700 |
commit | 360aa640a59f269b784848c0b2d6d462952750d9 (patch) | |
tree | cf5d41daeadb6f14a8c41637b7ae29ee05e6747a /Documentation/hwspinlock.txt | |
parent | bce6f5221374ba451a337d0a3773e6eb99dad3e8 (diff) |
hwspinlock: add the 'in_atomic' API
Add the 'in_atomic' mode which can be called from an atomic context.
This mode relies on the existing 'raw' mode (no lock, no preemption/irq
disabling) with the difference that the timeout is not based on jiffies
(jiffies won't increase when irq are disabled) but handled with
busy-waiting udelay() calls.
Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Diffstat (limited to 'Documentation/hwspinlock.txt')
-rw-r--r-- | Documentation/hwspinlock.txt | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/Documentation/hwspinlock.txt b/Documentation/hwspinlock.txt index c3403f9ae27a..6f03713b7003 100644 --- a/Documentation/hwspinlock.txt +++ b/Documentation/hwspinlock.txt @@ -153,6 +153,22 @@ 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); @@ -218,6 +234,19 @@ 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); Unlock a previously-locked hwspinlock. Always succeed, and can be called @@ -264,6 +293,16 @@ 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); Retrieve id number of a given hwspinlock. This is needed when an |