Introduce a helper function to determine the number of scans left in
the async command.
Signed-off-by: H Hartley Sweeten <hswee...@visionengravers.com>
Cc: Ian Abbott <abbo...@mev.co.uk>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/staging/comedi/comedidev.h | 2 ++
drivers/staging/comedi/drivers.c | 39 ++++++++++++++++++++++++++++++++++++++
2 files changed, 41 insertions(+)
diff --git a/drivers/staging/comedi/comedidev.h
b/drivers/staging/comedi/comedidev.h
index bff5a58..e3ef5cc 100644
--- a/drivers/staging/comedi/comedidev.h
+++ b/drivers/staging/comedi/comedidev.h
@@ -516,6 +516,8 @@ int comedi_dio_insn_config(struct comedi_device *, struct
comedi_subdevice *,
unsigned int comedi_dio_update_state(struct comedi_subdevice *,
unsigned int *data);
unsigned int comedi_bytes_per_scan(struct comedi_subdevice *s);
+unsigned int comedi_nscans_left(struct comedi_subdevice *s,
+ unsigned int nscans);
void comedi_inc_scan_progress(struct comedi_subdevice *s,
unsigned int num_bytes);
diff --git a/drivers/staging/comedi/drivers.c b/drivers/staging/comedi/drivers.c
index 4fc992b..a0bd48e 100644
--- a/drivers/staging/comedi/drivers.c
+++ b/drivers/staging/comedi/drivers.c
@@ -328,6 +328,45 @@ unsigned int comedi_bytes_per_scan(struct comedi_subdevice
*s)
EXPORT_SYMBOL_GPL(comedi_bytes_per_scan);
/**
+ * comedi_nscans_left - return the number of scans left in the command
+ * @s: comedi_subdevice struct
+ * @nscans: the expected number of scans
+ *
+ * If nscans is 0, the number of scans available in the async buffer will be
+ * used. Otherwise the expected number of scans will be used.
+ *
+ * If the async command has a stop_src of TRIG_COUNT, the nscans will be
+ * checked against the number of scans left in the command.
+ *
+ * The return value will then be either the expected number of scans or the
+ * number of scans remaining in the command.
+ */
+unsigned int comedi_nscans_left(struct comedi_subdevice *s,
+ unsigned int nscans)
+{
+ struct comedi_async *async = s->async;
+ struct comedi_cmd *cmd = &async->cmd;
+
+ if (nscans == 0) {
+ unsigned int nbytes = comedi_buf_read_n_available(s);
+
+ nscans = comedi_bytes_to_samples(s, nbytes);
+ }
+
+ if (cmd->stop_src == TRIG_COUNT) {
+ unsigned int scans_left = 0;
+
+ if (async->scans_done < cmd->stop_arg)
+ scans_left = cmd->stop_arg - async->scans_done;
+
+ if (nscans > scans_left)
+ nscans = scans_left;
+ }
+ return nscans;
+}
+EXPORT_SYMBOL_GPL(comedi_nscans_left);
+
+/**
* comedi_inc_scan_progress - update scan progress in asynchronous command
* @s: comedi_subdevice struct
* @num_bytes: amount of data in bytes to increment scan progress
--
2.0.3
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