From 4455d7c351dada63ec031a82760fa00d7806139a Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Wed, 22 Oct 2014 14:36:34 -0700 Subject: [PATCH] staging: comedi: comedi_buf: introduce comedi_buf_read_samples() Introduce a generic method to read samples from the async buffer. The number of requested samples is clampled to the number of samples that would fill the async buffer. The size of each sample is determined using the bytes_per_sample() helper. The number of bytes need are then read from the async buffer using comedi_read_array_from_buffer(). This will allow converting all the comedi drivers to use a common method to read data from the async buffer. Since comedi_read_array_from_buffer() sets the COMEDI_CB_BLOCK event after reading the data, those events can be removed from the drivers. In addition, comedi_inc_scan_progress() will automatically detect the end of scan and set the COMEDI_CB_EOS event. Those events can also be removed from the drivers. Signed-off-by: H Hartley Sweeten Reviewed-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/comedi_buf.c | 27 +++++++++++++++++++++++++++ drivers/staging/comedi/comedidev.h | 2 ++ 2 files changed, 29 insertions(+) diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c index c60a45ad12b9..88a7cae97811 100644 --- a/drivers/staging/comedi/comedi_buf.c +++ b/drivers/staging/comedi/comedi_buf.c @@ -575,3 +575,30 @@ unsigned int comedi_read_array_from_buffer(struct comedi_subdevice *s, return num_bytes; } EXPORT_SYMBOL_GPL(comedi_read_array_from_buffer); + +/** + * comedi_buf_read_samples - read sample data from comedi buffer + * @s: comedi_subdevice struct + * @data: destination + * @nsamples: maximum number of samples to read + * + * Reads up to nsamples from the comedi buffer associated with the subdevice, + * marks it as read and updates the acquisition scan progress. + * + * Returns the amount of data read in bytes. + */ +unsigned int comedi_buf_read_samples(struct comedi_subdevice *s, + void *data, unsigned int nsamples) +{ + unsigned int max_samples; + unsigned int nbytes; + + max_samples = s->async->prealloc_bufsz / bytes_per_sample(s); + if (nsamples > max_samples) + nsamples = max_samples; + + nbytes = nsamples * bytes_per_sample(s); + + return comedi_read_array_from_buffer(s, data, nbytes); +} +EXPORT_SYMBOL_GPL(comedi_buf_read_samples); diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h index fb8ff84dab35..ba4084bd5ed8 100644 --- a/drivers/staging/comedi/comedidev.h +++ b/drivers/staging/comedi/comedidev.h @@ -453,6 +453,8 @@ unsigned int comedi_write_array_to_buffer(struct comedi_subdevice *s, unsigned int num_bytes); unsigned int comedi_read_array_from_buffer(struct comedi_subdevice *s, void *data, unsigned int num_bytes); +unsigned int comedi_buf_read_samples(struct comedi_subdevice *s, + void *data, unsigned int nsamples); /* drivers.c - general comedi driver functions */ -- 2.39.5