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Diffstat (limited to 'drivers/staging/iio/Documentation/ring.txt')
| -rw-r--r-- | drivers/staging/iio/Documentation/ring.txt | 44 |
1 files changed, 21 insertions, 23 deletions
diff --git a/drivers/staging/iio/Documentation/ring.txt b/drivers/staging/iio/Documentation/ring.txt index 3696c364e644..7e99ef2b7bc0 100644 --- a/drivers/staging/iio/Documentation/ring.txt +++ b/drivers/staging/iio/Documentation/ring.txt @@ -1,57 +1,55 @@ -Ring buffer support within IIO +Buffer support within IIO This document is intended as a general overview of the functionality -a ring buffer may supply and how it is specified within IIO. For more -specific information on a given ring buffer implementation, see the -comments in the source code. Note that the intention is to allow -some drivers to specify ring buffers choice at probe or runtime, but -for now the selection is hard coded within a given driver. +a buffer may supply and how it is specified within IIO. For more +specific information on a given buffer implementation, see the +comments in the source code. Note that some drivers allow buffer +implementation to be selected at compile time via Kconfig options. -A given ring buffer implementation typically embedded a struct +A given buffer implementation typically embeds a struct iio_ring_buffer and it is a pointer to this that is provided to the IIO core. Access to the embedding structure is typically done via container_of functions. -struct iio_ring_buffer contains 4 function pointers -(preenable, postenable, predisable, postdisable). -These are used to perform implementation specific steps on either side -of the core changing it's current mode to indicate that the ring buffer +struct iio_ring_buffer contains a struct iio_ring_setup_ops *setup_ops +which in turn contains the 4 function pointers +(preenable, postenable, predisable and postdisable). +These are used to perform device specific steps on either side +of the core changing it's current mode to indicate that the buffer is enabled or disabled (along with enabling triggering etc as appropriate). Also in struct iio_ring_buffer is a struct iio_ring_access_funcs. The function pointers within here are used to allow the core to handle -as much ring buffer functionality as possible. Note almost all of these +as much buffer functionality as possible. Note almost all of these are optional. mark_in_use, unmark_in_use - Basically indicate that not changes should be made to the ring - buffer state that will effect the form of the data being captures - (e.g. scan elements or length) + Basically indicate that not changes should be made to the buffer state that + will effect the form of the data being captures (e.g. scan elements or length) store_to - If possible, push data to ring buffer. + If possible, push data to the buffer. read_last - If possible get the most recent entry from the buffer (without removal). + If possible, get the most recent scan from the buffer (without removal). This provides polling like functionality whilst the ring buffering is in use without a separate read from the device. -rip_lots - The primary ring buffer reading function. Note that it may well not return - as much data as requested. The deadoffset is used to indicate that some - initial data in the data array is not guaranteed to be valid. +rip_first_n + The primary buffer reading function. Note that it may well not return + as much data as requested. mark_param_changed Used to indicate that something has changed. Used in conjunction with request_update If parameters have changed that require reinitialization or configuration of - the ring buffer this will trigger it. + the buffer this will trigger it. get_bytes_per_datum, set_bytes_per_datum Get/set the number of bytes for a complete scan. (All samples + timestamp) get_length / set_length - Get/set the number of sample sets that may be held by the buffer. + Get/set the number of complete scans that may be held by the buffer. is_enabled Query if ring buffer is in use |