It is quite common for COMEDI subdevices that support commands to
support setting `scan_begin_src` to `TRIG_FOLLOW`. This means the next
scan begins once all conversions in the current scan are complete.
Support the following timing combinations for the AI subdevice:
scan_begin_src == TRIG_TIMER && convert_src == TRIG_TIMER
scan_begin_src == TRIG_TIMER && convert_src == TRIG_NOW
scan_begin_src == TRIG_FOLLOW && convert_src == TRIG_TIMER
The actual scan period in microseconds is stored in the `scan_period`
member of the private data structure `struct waveform_private`. An
`unsigned int` is still wide enough, because the conversion period is no
more than `UINT_MAX / 1000` microseconds and the number of conversions
is no more than 16 (`N_CHANS * 2`).
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
drivers/staging/comedi/drivers/comedi_test.c | 64 +++++++++++++++++++---------
1 file changed, 44 insertions(+), 20 deletions(-)
diff --git a/drivers/staging/comedi/drivers/comedi_test.c b/drivers/staging/comedi/drivers/comedi_test.c
index f011fbd..cc35bd6 100644
--- a/drivers/staging/comedi/drivers/comedi_test.c
+++ b/drivers/staging/comedi/drivers/comedi_test.c
@@ -239,7 +239,8 @@ static int waveform_ai_cmdtest(struct comedi_device *dev,
/* Step 1 : check if triggers are trivially valid */
err |= comedi_check_trigger_src(&cmd->start_src, TRIG_NOW);
- err |= comedi_check_trigger_src(&cmd->scan_begin_src, TRIG_TIMER);
+ err |= comedi_check_trigger_src(&cmd->scan_begin_src,
+ TRIG_FOLLOW | TRIG_TIMER);
err |= comedi_check_trigger_src(&cmd->convert_src,
TRIG_NOW | TRIG_TIMER);
err |= comedi_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
@@ -255,6 +256,9 @@ static int waveform_ai_cmdtest(struct comedi_device *dev,
/* Step 2b : and mutually compatible */
+ if (cmd->scan_begin_src == TRIG_FOLLOW && cmd->convert_src == TRIG_NOW)
+ err |= -EINVAL; /* scan period would be 0 */
+
if (err)
return 2;
@@ -262,11 +266,21 @@ static int waveform_ai_cmdtest(struct comedi_device *dev,
err |= comedi_check_trigger_arg_is(&cmd->start_arg, 0);
- if (cmd->convert_src == TRIG_NOW)
+ if (cmd->convert_src == TRIG_NOW) {
err |= comedi_check_trigger_arg_is(&cmd->convert_arg, 0);
+ } else { /* cmd->convert_src == TRIG_TIMER */
+ if (cmd->scan_begin_src == TRIG_FOLLOW) {
+ err |= comedi_check_trigger_arg_min(&cmd->convert_arg,
+ NSEC_PER_USEC);
+ }
+ }
- err |= comedi_check_trigger_arg_min(&cmd->scan_begin_arg,
- NSEC_PER_USEC);
+ if (cmd->scan_begin_src == TRIG_FOLLOW) {
+ err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, 0);
+ } else { /* cmd->scan_begin_src == TRIG_TIMER */
+ err |= comedi_check_trigger_arg_min(&cmd->scan_begin_arg,
+ NSEC_PER_USEC);
+ }
err |= comedi_check_trigger_arg_min(&cmd->chanlist_len, 1);
err |= comedi_check_trigger_arg_is(&cmd->scan_end_arg,
@@ -274,7 +288,7 @@ static int waveform_ai_cmdtest(struct comedi_device *dev,
if (cmd->stop_src == TRIG_COUNT)
err |= comedi_check_trigger_arg_min(&cmd->stop_arg, 1);
- else /* TRIG_NONE */
+ else /* cmd->stop_src == TRIG_NONE */
err |= comedi_check_trigger_arg_is(&cmd->stop_arg, 0);
if (err)
@@ -288,22 +302,27 @@ static int waveform_ai_cmdtest(struct comedi_device *dev,
arg = min(arg,
rounddown(UINT_MAX, (unsigned int)NSEC_PER_USEC));
arg = NSEC_PER_USEC * DIV_ROUND_CLOSEST(arg, NSEC_PER_USEC);
- /* limit convert_arg to keep scan_begin_arg in range */
- limit = UINT_MAX / cmd->scan_end_arg;
- limit = rounddown(limit, (unsigned int)NSEC_PER_SEC);
- arg = min(arg, limit);
+ if (cmd->scan_begin_arg == TRIG_TIMER) {
+ /* limit convert_arg to keep scan_begin_arg in range */
+ limit = UINT_MAX / cmd->scan_end_arg;
+ limit = rounddown(limit, (unsigned int)NSEC_PER_SEC);
+ arg = min(arg, limit);
+ }
err |= comedi_check_trigger_arg_is(&cmd->convert_arg, arg);
}
- /* round scan_begin_arg to nearest microsecond */
- arg = cmd->scan_begin_arg;
- arg = min(arg, rounddown(UINT_MAX, (unsigned int)NSEC_PER_USEC));
- arg = NSEC_PER_USEC * DIV_ROUND_CLOSEST(arg, NSEC_PER_USEC);
- if (cmd->convert_src == TRIG_TIMER) {
- /* but ensure scan_begin_arg is large enough */
- arg = max(arg, cmd->convert_arg * cmd->scan_end_arg);
+ if (cmd->scan_begin_src == TRIG_TIMER) {
+ /* round scan_begin_arg to nearest microsecond */
+ arg = cmd->scan_begin_arg;
+ arg = min(arg,
+ rounddown(UINT_MAX, (unsigned int)NSEC_PER_USEC));
+ arg = NSEC_PER_USEC * DIV_ROUND_CLOSEST(arg, NSEC_PER_USEC);
+ if (cmd->convert_src == TRIG_TIMER) {
+ /* but ensure scan_begin_arg is large enough */
+ arg = max(arg, cmd->convert_arg * cmd->scan_end_arg);
+ }
+ err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, arg);
}
- err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, arg);
if (err)
return 4;
@@ -323,13 +342,18 @@ static int waveform_ai_cmd(struct comedi_device *dev,
return -1;
}
- devpriv->scan_period = cmd->scan_begin_arg / NSEC_PER_USEC;
-
if (cmd->convert_src == TRIG_NOW)
devpriv->convert_period = 0;
- else /* TRIG_TIMER */
+ else /* cmd->convert_src == TRIG_TIMER */
devpriv->convert_period = cmd->convert_arg / NSEC_PER_USEC;
+ if (cmd->scan_begin_src == TRIG_FOLLOW) {
+ devpriv->scan_period = devpriv->convert_period *
+ cmd->scan_end_arg;
+ } else { /* cmd->scan_begin_src == TRIG_TIMER */
+ devpriv->scan_period = cmd->scan_begin_arg / NSEC_PER_USEC;
+ }
+
devpriv->last = ktime_get();
devpriv->usec_current =
((u32)ktime_to_us(devpriv->last)) % devpriv->usec_period;
--
2.6.1
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