Some applications need to be able to flush [1] the hardware fifo of the device and to receive events of when that happened [2] so that it can ignore stale data.
This patch adds a new event (IIO_EV_TYPE_HWFIFO_FLUSHED) that should be sent to userspace when a flush has been completed. The application will be able to identify which are the samples to ignore based on the timestamp of the event. To allow applications to accurately generate a hardware fifo flush on demand, this patch also adds a new sysfs entry that triggers a hardware fifo flush when written to. [1] https://source.android.com/devices/sensors/hal-interface.html#flush_sensor [2] https://source.android.com/devices/sensors/hal-interface.html#metadata_flush_complete_events Signed-off-by: Octavian Purdila <[email protected]> --- Documentation/ABI/testing/sysfs-bus-iio | 11 +++++++++++ include/linux/iio/sysfs.h | 3 +++ include/uapi/linux/iio/types.h | 1 + 3 files changed, 15 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio index 866b4ec..bb4d8de 100644 --- a/Documentation/ABI/testing/sysfs-bus-iio +++ b/Documentation/ABI/testing/sysfs-bus-iio @@ -1375,3 +1375,14 @@ Description: The emissivity ratio of the surface in the field of view of the contactless temperature sensor. Emissivity varies from 0 to 1, with 1 being the emissivity of a black body. + +What: /sys/bus/iio/devices/iio:deviceX/buffer/hwfifo_flush +KernelVersion: 4.2 +Contact: [email protected] +Description: + Write only entry that accepts a single strictly positive integer + specifying the number of samples to flush from the hardware fifo + to the device buffer. When the flush is completed an + IIO_EV_TYPE_HWFIFO_FLUSHED event is generated. The event has the + timestamp equal with the timestamp of last sample that was + flushed from the hardware fifo. diff --git a/include/linux/iio/sysfs.h b/include/linux/iio/sysfs.h index 8822bab..8fcc25b 100644 --- a/include/linux/iio/sysfs.h +++ b/include/linux/iio/sysfs.h @@ -136,4 +136,7 @@ struct iio_const_attr { #define IIO_DEV_ATTR_HWFIFO_WATERMARK(_hwfifo_get_wm) \ IIO_DEVICE_ATTR(hwfifo_watermark, S_IRUGO, _hwfifo_get_wm, NULL, 0) +#define IIO_DEV_ATTR_HWFIFO_FLUSH(_hwfifo_flush) \ + IIO_DEVICE_ATTR(hwfifo_flush, S_IWUSR, NULL, _hwfifo_flush, 0) + #endif /* _INDUSTRIAL_IO_SYSFS_H_ */ diff --git a/include/uapi/linux/iio/types.h b/include/uapi/linux/iio/types.h index 5c46019..4600157 100644 --- a/include/uapi/linux/iio/types.h +++ b/include/uapi/linux/iio/types.h @@ -79,6 +79,7 @@ enum iio_event_type { IIO_EV_TYPE_THRESH_ADAPTIVE, IIO_EV_TYPE_MAG_ADAPTIVE, IIO_EV_TYPE_CHANGE, + IIO_EV_TYPE_HWFIFO_FLUSHED, }; enum iio_event_direction { -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
