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device: simplify synchronization

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Takes advantage of the fact that microkernel tasks can now wait on
nanokernel objects to simplify the device synchronization code.

Change-Id: I5b8d21eaccde9db8b63dd906ef982494a6170271
Signed-off-by: Peter Mitsis <peter.mitsis@windriver.com>
This commit is contained in:
Peter Mitsis 2016-04-18 15:49:49 -04:00 • committed by Anas Nashif
commit 542c37fe9c
1 changed files with 0 additions and 115 deletions
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115
include/device.h
View file

@ -426,27 +426,12 @@ int device_busy_check(struct device *chk_dev);
#include <microkernel.h>
#endif
#ifdef CONFIG_MICROKERNEL
enum device_sync_waiter {
DEVICE_SYNC_WAITER_NONE,
DEVICE_SYNC_WAITER_FIBER,
DEVICE_SYNC_WAITER_TASK,
};
#endif
/**
* Specific type for synchronizing calls among the 2 possible contexts
*/
typedef struct {
/** Nanokernel semaphore used for fiber context */
struct nano_sem f_sem;
#ifdef CONFIG_MICROKERNEL
/** Microkernel semaphore used for task context */
struct _k_sem_struct _t_sem;
ksem_t t_sem;
enum device_sync_waiter waiter;
bool device_ready;
#endif
} device_sync_call_t;
@ -458,106 +443,8 @@ typedef struct {
static inline void device_sync_call_init(device_sync_call_t *sync)
{
nano_sem_init(&sync->f_sem);
#ifdef CONFIG_MICROKERNEL
sync->_t_sem.waiters = NULL;
sync->_t_sem.level = sync->_t_sem.count = 0;
sync->t_sem = (ksem_t)&sync->_t_sem;
sync->waiter = DEVICE_SYNC_WAITER_NONE;
sync->device_ready = false;
#endif
}
#ifdef CONFIG_MICROKERNEL
/*
* The idle task cannot block and is used during boot, and thus polls a
* nanokernel semaphore instead of waiting on a microkernel semaphore.
*/
static inline bool _is_blocking_task(void)
{
bool is_task = sys_execution_context_type_get() == NANO_CTX_TASK;
bool is_idle_task = task_priority_get() == (CONFIG_NUM_TASK_PRIORITIES - 1);
return is_task && !is_idle_task;
}
/**
* @brief Wait for the isr to complete the synchronous call
* Note: In a microkernel built this function will take care of the caller
* context and thus use the right attribute to handle the synchronization.
*
* @param sync A pointer to a valid device_sync_call_t
*/
static inline void device_sync_call_wait(device_sync_call_t *sync)
{
/* protect the state of device_ready and waiter fields */
int key = irq_lock();
if (sync->device_ready) {
sync->device_ready = false;
/*
* If device_ready was set, the waiter field had to be NONE, so we
* don't have to reset it.
*/
irq_unlock(key);
return;
}
if (_is_blocking_task()) {
sync->waiter = DEVICE_SYNC_WAITER_TASK;
irq_unlock(key);
task_sem_take(sync->t_sem, TICKS_UNLIMITED);
} else {
sync->waiter = DEVICE_SYNC_WAITER_FIBER;
irq_unlock(key);
nano_sem_take(&sync->f_sem, TICKS_UNLIMITED);
}
sync->waiter = DEVICE_SYNC_WAITER_NONE;
/* if we get here, device_ready was not set: we don't have to reset it */
}
/**
* @brief Signal the waiter about synchronization completion
* Note: In a microkernel built this function will take care of the waiter
* context and thus use the right attribute to signale the completion.
*
* @param sync A pointer to a valid device_sync_call_t
*/
static inline void device_sync_call_complete(device_sync_call_t *sync)
{
static void (*func[3])(ksem_t sema) = {
isr_sem_give,
fiber_sem_give,
task_sem_give
};
/* protect the state of device_ready and waiter fields */
int key = irq_lock();
if (sync->waiter == DEVICE_SYNC_WAITER_NONE) {
sync->device_ready = true;
irq_unlock(key);
return;
}
/*
* It's safe to unlock interrupts here since we know there was a waiter,
* and only one thread is allowed to wait on the object, so the state of
* waiter will not change and the device_ready flag will not get set.
*/
irq_unlock(key);
if (sync->waiter == DEVICE_SYNC_WAITER_TASK) {
func[sys_execution_context_type_get()](sync->t_sem);
} else /* fiber */ {
nano_sem_give(&sync->f_sem);
}
}
#else
/**
* @brief Wait for the isr to complete the synchronous call
* Note: It will simply wait on the internal semaphore.
@ -580,8 +467,6 @@ static inline void device_sync_call_complete(device_sync_call_t *sync)
nano_sem_give(&sync->f_sem);
}
#endif /* CONFIG_MICROKERNEL || CONFIG_NANOKERNEL */
#ifdef __cplusplus
}
#endif