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sensor: add SNIOC_READLAST

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If enable SNIOC_READLAST, sensor_read will return 0
when there is no new data until last read.

Signed-off-by: Jiuzhu Dong <dongjiuzhu1@xiaomi.com>
This commit is contained in:
Jiuzhu Dong 2022-04-26 14:01:11 +08:00 committed by Xiang Xiao
parent 2f5727b102
commit 6f3873dfa2
2 changed files with 56 additions and 30 deletions
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77
drivers/sensors/sensor.c
View File

@ -95,6 +95,7 @@ struct sensor_upperhalf_s
struct circbuf_s buffer; /* The circular buffer of sensor device */
sem_t exclsem; /* Manages exclusive access to file operations */
struct list_node userlist; /* List of users */
bool readlast; /* The flag of readlast */
};
/****************************************************************************
@ -525,52 +526,61 @@ static ssize_t sensor_read(FAR struct file *filep, FAR char *buffer,
}
else
{
/* We must make sure that when the semaphore is equal to 1, there must
* be events available in the buffer, so we use a while statement to
* synchronize this case that other read operations consume events
* that have just entered the buffer.
/* If readlast is true, you can always read the last data
* in the circbuffer as initial value for new users when the
* sensor device has not yet generated new data, otherwise,
* it will return 0 when there isn't new data.
*/
while (circbuf_is_empty(&upper->buffer))
if (upper->readlast)
{
if (filep->f_oflags & O_NONBLOCK)
if (circbuf_is_empty(&upper->buffer))
{
ret = -EAGAIN;
ret = -ENODATA;
goto out;
}
else
{
nxsem_post(&upper->exclsem);
ret = nxsem_wait_uninterruptible(&user->buffersem);
if (ret < 0)
{
return ret;
}
ret = nxsem_wait(&upper->exclsem);
if (ret < 0)
{
return ret;
}
if (user->generation == upper->state.generation)
{
user->generation--;
}
}
/* Always read the last data in the circbuffer as initial value
* for new users when the sensor device has not yet generated
* new data.
*/
if (user->generation == upper->state.generation)
else
{
user->generation--;
/* We must make sure that when the semaphore is equal to 1,
* there must be events available in the buffer, so we use a
* while statement to synchronize this case that other read
* operations consume events that have just entered the buffer.
*/
while (circbuf_is_empty(&upper->buffer) ||
user->generation == upper->state.generation)
{
if (filep->f_oflags & O_NONBLOCK)
{
ret = -EAGAIN;
goto out;
}
else
{
nxmutex_unlock(&upper->lock);
ret = nxsem_wait_uninterruptible(&user->buffersem);
if (ret < 0)
{
return ret;
}
nxmutex_lock(&upper->lock);
}
}
}
/* If user's generation isn't within circbuffer range, the
* oldest data in circbuffer are returned to the users.
*/
else if (!sensor_in_range(upper->state.generation - lower->nbuffer,
user->generation, upper->state.generation))
if (!sensor_in_range(upper->state.generation - lower->nbuffer,
user->generation, upper->state.generation))
{
user->generation = upper->state.generation - lower->nbuffer;
@ -704,6 +714,12 @@ static int sensor_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
}
break;
case SNIOC_READLAST:
{
upper->readlast = !!arg;
}
break;
default:
/* Lowerhalf driver process other cmd. */
@ -969,6 +985,7 @@ int sensor_custom_register(FAR struct sensor_lowerhalf_s *lower,
/* Initialize the upper-half data structure */
list_initialize(&upper->userlist);
upper->readlast = true;
upper->state.esize = esize;
upper->state.min_interval = ULONG_MAX;
upper->state.min_latency = ULONG_MAX;

9
include/nuttx/sensors/ioctl.h
View File

@ -326,4 +326,13 @@
#define SNIOC_UNREGISTER _SNIOC(0x0090)
#endif
/* Command: SNIOC_READLAST
* Description: If enable readlast, there is no data update in time,
* the latest data can always be returned.
* Disable readlast, if there is no data update, return 0.
* Argument: True or false
*/
#define SNIOC_READLAST _SNIOC(0x0091)
#endif /* __INCLUDE_NUTTX_SENSORS_IOCTL_H */