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Commit a6b7dbb2 authored by H Hartley Sweeten's avatar H Hartley Sweeten Committed by Greg Kroah-Hartman
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staging: comedi: das1800: allow setting the external trigger polarity 



The external pin TGIN can be used to start and/or stop the analog input
command. Currently the driver only supports negative edge polarity for
this signal.

Add support to allow the user to select positive edge polarity using
the CR_INVERT flag.

Signed-off-by: default avatarH Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a2706b09

drivers/staging/comedi/drivers/das1800.c

+15 −1
Original line number Diff line number Diff line
@@ -60,6 +60,9 @@ 
 * If TRIG_EXT is used for both the start_src and stop_src, the first TGIN

 * trigger starts the command, and the second trigger will stop it. If only

 * one is TRIG_EXT, the first trigger will either stop or start the command.

 * The external pin TGIN is normally set for negative edge triggering. It

 * can be set to positive edge with the CR_INVERT flag. If TRIG_EXT is used

 * for both the start_src and stop_src they must have the same polarity.

 *

 * Minimum conversion speed is limited to 64 microseconds (convert_arg <= 64000)

 * for 'burst' scans. This limitation does not apply for 'paced' scans. The
@@ -105,6 +108,7 @@ 
#define   CGSL                    0x8

#define   TGEN                    0x10

#define   TGSL                    0x20

#define   TGPL                    0x40

#define   ATEN                    0x80

#define DAS1800_CONTROL_B       0x5

#define   DMA_CH5                 0x1
@@ -671,11 +675,17 @@ static int das1800_ai_cmdtest(struct comedi_device *dev, 
	    cmd->convert_src != TRIG_TIMER)

		err |= -EINVAL;



	/* the external pin TGIN must use the same polarity */

	if (cmd->start_src == TRIG_EXT && cmd->stop_src == TRIG_EXT)

		err |= comedi_check_trigger_arg_is(&cmd->start_arg,

						   cmd->stop_arg);



	if (err)

		return 2;



	/* Step 3: check if arguments are trivially valid */



	if (cmd->start_arg == TRIG_NOW)

		err |= comedi_check_trigger_arg_is(&cmd->start_arg, 0);



	if (cmd->convert_src == TRIG_TIMER) {
@@ -868,6 +878,10 @@ static int das1800_ai_cmd(struct comedi_device *dev, 
		control_a |= TGEN | CGSL;

	else /* TRIG_NOW */

		control_a |= CGEN;

	if (control_a & (ATEN | TGEN)) {

		if ((cmd->start_arg & CR_INVERT) || (cmd->stop_arg & CR_INVERT))

			control_a |= TGPL;

	}



	control_c = das1800_ai_chanspec_bits(s, cmd->chanlist[0]);

	/* set clock source to internal or external */