Commit 9a1f7223 authored by Ian Abbott's avatar Ian Abbott Committed by Greg Kroah-Hartman
Browse files

staging: comedi: rtd520: add a few comments 



H Hartley Sweeten's recent series of patches to clean up the rtd520
driver made some of the register accesses harder to understand.  Add a
few comments to provide some clues to the reader.

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 3cdefc92

drivers/staging/comedi/drivers/rtd520.c

+18 −5
Original line number Diff line number Diff line
@@ -494,6 +494,7 @@ static int rtd520_probe_fifo_depth(struct comedi_device *dev) 


	writel(0, devpriv->las0 + LAS0_ADC_FIFO_CLEAR);

	rtd_load_channelgain_list(dev, 1, &chanspec);

	/* ADC conversion trigger source: SOFTWARE */

	writel(0, devpriv->las0 + LAS0_ADC_CONVERSION);

	/* convert  samples */

	for (i = 0; i < limit; ++i) {
@@ -544,7 +545,7 @@ static int rtd_ai_rinsn(struct comedi_device *dev, 
	/* write channel to multiplexer and clear channel gain table */

	rtd_load_channelgain_list(dev, 1, &insn->chanspec);



	/* set conversion source */

	/* ADC conversion trigger source: SOFTWARE */

	writel(0, devpriv->las0 + LAS0_ADC_CONVERSION);



	/* convert n samples */
@@ -908,8 +909,9 @@ abortTransfer: 
	/* fall into transferDone */



transferDone:

	/* pacer stop source: SOFTWARE */

	writel(0, devpriv->las0 + LAS0_PACER_STOP);

	writel(0, devpriv->las0 + LAS0_PACER);

	writel(0, devpriv->las0 + LAS0_PACER);	/* stop pacer */

	writel(0, devpriv->las0 + LAS0_ADC_CONVERSION);

	devpriv->intMask = 0;

	writew(devpriv->intMask, devpriv->las0 + LAS0_IT);
@@ -1180,8 +1182,9 @@ static int rtd_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s) 
	int timer;



	/* stop anything currently running */

	/* pacer stop source: SOFTWARE */

	writel(0, devpriv->las0 + LAS0_PACER_STOP);

	writel(0, devpriv->las0 + LAS0_PACER);

	writel(0, devpriv->las0 + LAS0_PACER);	/* stop pacer */

	writel(0, devpriv->las0 + LAS0_ADC_CONVERSION);

	devpriv->intMask = 0;

	writew(devpriv->intMask, devpriv->las0 + LAS0_IT);
@@ -1215,12 +1218,17 @@ static int rtd_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s) 
	/* setup the common case and override if needed */

	if (cmd->chanlist_len > 1) {

		/*DPRINTK ("rtd520: Multi channel setup\n"); */

		/* pacer start source: SOFTWARE */

		writel(0, devpriv->las0 + LAS0_PACER_START);

		/* burst trigger source: PACER */

		writel(1, devpriv->las0 + LAS0_BURST_START);

		/* ADC conversion trigger source: BURST */

		writel(2, devpriv->las0 + LAS0_ADC_CONVERSION);

	} else {		/* single channel */

		/*DPRINTK ("rtd520: single channel setup\n"); */

		/* pacer start source: SOFTWARE */

		writel(0, devpriv->las0 + LAS0_PACER_START);

		/* ADC conversion trigger source: PACER */

		writel(1, devpriv->las0 + LAS0_ADC_CONVERSION);

	}

	writel((devpriv->fifoLen / 2 - 1) & 0xffff, devpriv->las0 + LAS0_ACNT);
@@ -1269,7 +1277,9 @@ static int rtd_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s) 
		devpriv->transCount = 0;

		devpriv->flags &= ~SEND_EOS;

	}

	/* pacer clock source: INTERNAL 8MHz */

	writel(1, devpriv->las0 + LAS0_PACER_SELECT);

	/* just interrupt, don't stop */

	writel(1, devpriv->las0 + LAS0_ACNT_STOP_ENABLE);



	/* BUG??? these look like enumerated values, but they are bit fields */
@@ -1305,6 +1315,7 @@ static int rtd_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s) 
		break;



	case TRIG_EXT:

		/* pacer start source: EXTERNAL */

		writel(1, devpriv->las0 + LAS0_PACER_START);

		break;
@@ -1327,6 +1338,7 @@ static int rtd_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s) 
		break;



	case TRIG_EXT:		/* external */

		/* burst trigger source: EXTERNAL */

		writel(2, devpriv->las0 + LAS0_BURST_START);

		break;
@@ -1378,7 +1390,7 @@ static int rtd_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s) 


	/* BUG: start_src is ASSUMED to be TRIG_NOW */

	/* BUG? it seems like things are running before the "start" */

	readl(devpriv->las0 + LAS0_PACER);

	readl(devpriv->las0 + LAS0_PACER);	/* start pacer */

	return 0;

}
@@ -1391,8 +1403,9 @@ static int rtd_ai_cancel(struct comedi_device *dev, struct comedi_subdevice *s) 
	u32 overrun;

	u16 status;



	/* pacer stop source: SOFTWARE */

	writel(0, devpriv->las0 + LAS0_PACER_STOP);

	writel(0, devpriv->las0 + LAS0_PACER);

	writel(0, devpriv->las0 + LAS0_PACER);	/* stop pacer */

	writel(0, devpriv->las0 + LAS0_ADC_CONVERSION);

	devpriv->intMask = 0;

	writew(devpriv->intMask, devpriv->las0 + LAS0_IT);

CRA Git | Maintained and supported by SUSTech CRA and CCSE