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hwspinlock: add the 'in_atomic' API

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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>
This commit is contained in:
Fabien Dessenne
2019-03-07 16:58:23 +01:00
committed by Bjorn Andersson
parent bce6f52213
commit 360aa640a5
3 changed files with 127 additions and 16 deletions
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61
include/linux/hwspinlock.h
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@@ -14,9 +14,10 @@
#include <linux/sched.h>
/* hwspinlock mode argument */
#define HWLOCK_IRQSTATE 0x01 /* Disable interrupts, save state */
#define HWLOCK_IRQ 0x02 /* Disable interrupts, don't save state */
#define HWLOCK_RAW 0x03
#define HWLOCK_IRQSTATE 0x01 /* Disable interrupts, save state */
#define HWLOCK_IRQ 0x02 /* Disable interrupts, don't save state */
#define HWLOCK_RAW 0x03
#define HWLOCK_IN_ATOMIC 0x04 /* Called while in atomic context */
struct device;
struct device_node;
@@ -222,6 +223,23 @@ static inline int hwspin_trylock_raw(struct hwspinlock *hwlock)
return __hwspin_trylock(hwlock, HWLOCK_RAW, NULL);
}
/**
* hwspin_trylock_in_atomic() - attempt to lock a specific hwspinlock
* @hwlock: an hwspinlock which we want to trylock
*
* This function attempts to lock an hwspinlock, and will immediately fail
* if the hwspinlock is already taken.
*
* This function shall be called only from an atomic context.
*
* Returns 0 if we successfully locked the hwspinlock, -EBUSY if
* the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
*/
static inline int hwspin_trylock_in_atomic(struct hwspinlock *hwlock)
{
return __hwspin_trylock(hwlock, HWLOCK_IN_ATOMIC, NULL);
}
/**
* hwspin_trylock() - attempt to lock a specific hwspinlock
* @hwlock: an hwspinlock which we want to trylock
@@ -312,6 +330,28 @@ int hwspin_lock_timeout_raw(struct hwspinlock *hwlock, unsigned int to)
return __hwspin_lock_timeout(hwlock, to, HWLOCK_RAW, NULL);
}
/**
* hwspin_lock_timeout_in_atomic() - lock an hwspinlock with timeout limit
* @hwlock: the hwspinlock to be locked
* @to: timeout value in msecs
*
* This function locks the underlying @hwlock. If the @hwlock
* is already taken, the function will busy loop waiting for it to
* be released, but give up when @timeout msecs have elapsed.
*
* This function shall be called only from an atomic context and the timeout
* value shall not exceed a few msecs.
*
* Returns 0 when the @hwlock was successfully taken, and an appropriate
* error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
* busy after @timeout msecs). The function will never sleep.
*/
static inline
int hwspin_lock_timeout_in_atomic(struct hwspinlock *hwlock, unsigned int to)
{
return __hwspin_lock_timeout(hwlock, to, HWLOCK_IN_ATOMIC, NULL);
}
/**
* hwspin_lock_timeout() - lock an hwspinlock with timeout limit
* @hwlock: the hwspinlock to be locked
@@ -386,6 +426,21 @@ static inline void hwspin_unlock_raw(struct hwspinlock *hwlock)
__hwspin_unlock(hwlock, HWLOCK_RAW, NULL);
}
/**
* hwspin_unlock_in_atomic() - unlock hwspinlock
* @hwlock: a previously-acquired hwspinlock which we want to unlock
*
* This function will unlock a specific hwspinlock.
*
* @hwlock must be already locked (e.g. by hwspin_trylock()) before calling
* this function: it is a bug to call unlock on a @hwlock that is already
* unlocked.
*/
static inline void hwspin_unlock_in_atomic(struct hwspinlock *hwlock)
{
__hwspin_unlock(hwlock, HWLOCK_IN_ATOMIC, NULL);
}
/**
* hwspin_unlock() - unlock hwspinlock
* @hwlock: a previously-acquired hwspinlock which we want to unlock