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Commit 581867bd authored by H Hartley Sweeten's avatar H Hartley Sweeten Committed by Greg Kroah-Hartman
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staging: comedi: dt282x: refactor dt282x_ns_to_timer() 



Define the pacer clock limits and remove the magic numbers. Refactor
the code to use a common path to return the actual 'ns' timing and
the timer divisor value.

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 47470216

drivers/staging/comedi/drivers/dt282x.c

+24 −12
Original line number Diff line number Diff line
@@ -113,6 +113,17 @@ 
#define DT2821_SUPCSR_XCLK		BIT(1)

#define DT2821_SUPCSR_BDINIT		BIT(0)

#define DT2821_TMRCTR_REG		0x0e

#define DT2821_TMRCTR_PRESCALE(x)	(((x) & 0xf) << 8)

#define DT2821_TMRCTR_DIVIDER(x)	((255 - ((x) & 0xff)) << 0)



/* Pacer Clock */

#define DT2821_OSC_BASE		250	/* 4 MHz (in nanoseconds) */

#define DT2821_PRESCALE(x)	BIT(x)

#define DT2821_PRESCALE_MAX	15

#define DT2821_DIVIDER_MAX	255

#define DT2821_OSC_MAX		(DT2821_OSC_BASE *			\

				 DT2821_PRESCALE(DT2821_PRESCALE_MAX) *	\

				 DT2821_DIVIDER_MAX)



static const struct comedi_lrange range_dt282x_ai_lo_bipolar = {

	4, {
@@ -365,10 +376,10 @@ static unsigned int dt282x_ns_to_timer(unsigned int *ns, unsigned int flags) 
{

	unsigned int prescale, base, divider;



	for (prescale = 0; prescale < 16; prescale++) {

		if (prescale == 1)

	for (prescale = 0; prescale <= DT2821_PRESCALE_MAX; prescale++) {

		if (prescale == 1)	/* 0 and 1 are both divide by 1 */

			continue;

		base = 250 * (1 << prescale);

		base = DT2821_OSC_BASE * DT2821_PRESCALE(prescale);

		switch (flags & CMDF_ROUND_MASK) {

		case CMDF_ROUND_NEAREST:

		default:
@@ -381,15 +392,17 @@ static unsigned int dt282x_ns_to_timer(unsigned int *ns, unsigned int flags) 
			divider = DIV_ROUND_UP(*ns, base);

			break;

		}

		if (divider < 256) {

			*ns = divider * base;

			return (prescale << 8) | (255 - divider);

		if (divider <= DT2821_DIVIDER_MAX)

			break;

	}

	if (divider > DT2821_DIVIDER_MAX) {

		prescale = DT2821_PRESCALE_MAX;

		divider = DT2821_DIVIDER_MAX;

		base = DT2821_OSC_BASE * DT2821_PRESCALE(prescale);

	}

	base = 250 * (1 << 15);

	divider = 255;

	*ns = divider * base;

	return (15 << 8) | (255 - divider);

	return DT2821_TMRCTR_PRESCALE(prescale) |

	       DT2821_TMRCTR_DIVIDER(divider);

}



static void dt282x_munge(struct comedi_device *dev,
@@ -689,8 +702,7 @@ static int dt282x_ai_cmdtest(struct comedi_device *dev, 


	err |= comedi_check_trigger_arg_min(&cmd->convert_arg, 4000);



#define SLOWEST_TIMER	(250*(1<<15)*255)

	err |= comedi_check_trigger_arg_max(&cmd->convert_arg, SLOWEST_TIMER);

	err |= comedi_check_trigger_arg_max(&cmd->convert_arg, DT2821_OSC_MAX);

	err |= comedi_check_trigger_arg_min(&cmd->convert_arg, board->ai_speed);

	err |= comedi_check_trigger_arg_is(&cmd->scan_end_arg,

					   cmd->chanlist_len);