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Commit 783ddaeb authored by Ian Abbott's avatar Ian Abbott Committed by Greg Kroah-Hartman
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staging: comedi: comedi_test: support scan_begin_src == TRIG_FOLLOW 



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: default avatarIan Abbott <abbotti@mev.co.uk>
Reviewed-by: default avatarH Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5afdcad2

drivers/staging/comedi/drivers/comedi_test.c

+44 −20
Original line number Diff line number Diff line
@@ -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);

		}

	}



	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);

		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);

	}



	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 = 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);

	}



	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;