diff options
Diffstat (limited to 'include/linux/iio')
| -rw-r--r-- | include/linux/iio/iio.h | 49 |
1 files changed, 48 insertions, 1 deletions
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h index 85cb924debd9..233d2e6b7721 100644 --- a/include/linux/iio/iio.h +++ b/include/linux/iio/iio.h @@ -315,7 +315,54 @@ static inline bool iio_channel_has_available(const struct iio_chan_spec *chan, s64 iio_get_time_ns(const struct iio_dev *indio_dev); unsigned int iio_get_time_res(const struct iio_dev *indio_dev); -/* Device operating modes */ +/* + * Device operating modes + * @INDIO_DIRECT_MODE: There is an access to either: + * a) The last single value available for devices that do not provide + * on-demand reads. + * b) A new value after performing an on-demand read otherwise. + * On most devices, this is a single-shot read. On some devices with data + * streams without an 'on-demand' function, this might also be the 'last value' + * feature. Above all, this mode internally means that we are not in any of the + * other modes, and sysfs reads should work. + * Device drivers should inform the core if they support this mode. + * @INDIO_BUFFER_TRIGGERED: Common mode when dealing with kfifo buffers. + * It indicates that an explicit trigger is required. This requests the core to + * attach a poll function when enabling the buffer, which is indicated by the + * _TRIGGERED suffix. + * The core will ensure this mode is set when registering a triggered buffer + * with iio_triggered_buffer_setup(). + * @INDIO_BUFFER_SOFTWARE: Another kfifo buffer mode, but not event triggered. + * No poll function can be attached because there is no triggered infrastructure + * we can use to cause capture. There is a kfifo that the driver will fill, but + * not "only one scan at a time". Typically, hardware will have a buffer that + * can hold multiple scans. Software may read one or more scans at a single time + * and push the available data to a Kfifo. This means the core will not attach + * any poll function when enabling the buffer. + * The core will ensure this mode is set when registering a simple kfifo buffer + * with devm_iio_kfifo_buffer_setup(). + * @INDIO_BUFFER_HARDWARE: For specific hardware, if unsure do not use this mode. + * Same as above but this time the buffer is not a kfifo where we have direct + * access to the data. Instead, the consumer driver must access the data through + * non software visible channels (or DMA when there is no demux possible in + * software) + * The core will ensure this mode is set when registering a dmaengine buffer + * with devm_iio_dmaengine_buffer_setup(). + * @INDIO_EVENT_TRIGGERED: Very unusual mode. + * Triggers usually refer to an external event which will start data capture. + * Here it is kind of the opposite as, a particular state of the data might + * produce an event which can be considered as an event. We don't necessarily + * have access to the data itself, but to the event produced. For example, this + * can be a threshold detector. The internal path of this mode is very close to + * the INDIO_BUFFER_TRIGGERED mode. + * The core will ensure this mode is set when registering a triggered event. + * @INDIO_HARDWARE_TRIGGERED: Very unusual mode. + * Here, triggers can result in data capture and can be routed to multiple + * hardware components, which make them close to regular triggers in the way + * they must be managed by the core, but without the entire interrupts/poll + * functions burden. Interrupts are irrelevant as the data flow is hardware + * mediated and distributed. + */ #define INDIO_DIRECT_MODE 0x01 #define INDIO_BUFFER_TRIGGERED 0x02 #define INDIO_BUFFER_SOFTWARE 0x04 |