staging: comedi: 8253.h: tidy up the i8253_cascade_ns_to_timer*() users

Introduce a couple defines for the common 8254 oscillator base values
used in the comedi drivers and remove the custom defines and open
coded values.

Change the i8253_cascade_ns_to_timer_2div() calls in the drivers to
the more generic i8253_cascade_ns_to_timer(). They are identical due
to the #define in the 8253.h header.

Remove the extra mask by TRIG_ROUND_MASK of the 'round_mode' parameter
to i8253_cascade_ns_to_timer(). That function already handles the mask.

Tidy up all the calls to i8253_cascade_ns_to_timer().

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

16 files changed, 161 insertions, 181 deletions

diff --git a/drivers/staging/comedi/drivers/8253.h b/drivers/staging/comedi/drivers/8253.h
index 3abedcd2527b..e3d737cf7302 100644
--- a/drivers/staging/comedi/drivers/8253.h
+++ b/drivers/staging/comedi/drivers/8253.h
@@ -21,6 +21,15 @@
 
 #include "../comedi.h"
 
+/*
+ * Common oscillator base values in nanoseconds
+ */
+#define I8254_OSC_BASE_10MHZ		100
+#define I8254_OSC_BASE_5MHZ		200
+#define I8254_OSC_BASE_4MHZ		250
+#define I8254_OSC_BASE_2MHZ		500
+#define I8254_OSC_BASE_1MHZ		1000
+
 #define i8253_cascade_ns_to_timer i8253_cascade_ns_to_timer_2div
 
 static inline void i8253_cascade_ns_to_timer_2div_old(int i8253_osc_base,
diff --git a/drivers/staging/comedi/drivers/adl_pci9111.c b/drivers/staging/comedi/drivers/adl_pci9111.c
index 89ca5078e8b3..4db46f0f315e 100644
--- a/drivers/staging/comedi/drivers/adl_pci9111.c
+++ b/drivers/staging/comedi/drivers/adl_pci9111.c
@@ -86,8 +86,6 @@ TODO:
 #define PCI9111_AI_INSTANT_READ_UDELAY_US	2
 #define PCI9111_AI_INSTANT_READ_TIMEOUT		100
 
-#define PCI9111_8254_CLOCK_PERIOD_NS		500
-
 /*
  * IO address map and bit defines
  */
@@ -393,11 +391,10 @@ static int pci9111_ai_do_cmd_test(struct comedi_device *dev,
 
 	if (cmd->convert_src == TRIG_TIMER) {
 		tmp = cmd->convert_arg;
-		i8253_cascade_ns_to_timer_2div(PCI9111_8254_CLOCK_PERIOD_NS,
-					       &dev_private->div1,
-					       &dev_private->div2,
-					       &cmd->convert_arg,
-					       cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_2MHZ,
+					  &dev_private->div1,
+					  &dev_private->div2,
+					  &cmd->convert_arg, cmd->flags);
 		if (tmp != cmd->convert_arg)
 			error++;
 	}
diff --git a/drivers/staging/comedi/drivers/adl_pci9118.c b/drivers/staging/comedi/drivers/adl_pci9118.c
index f50dbea67240..bd5c8bbad090 100644
--- a/drivers/staging/comedi/drivers/adl_pci9118.c
+++ b/drivers/staging/comedi/drivers/adl_pci9118.c
@@ -792,7 +792,8 @@ static void pci9118_calc_divisors(char mode, struct comedi_device *dev,
 	case 4:
 		if (*tim2 < this_board->ai_ns_min)
 			*tim2 = this_board->ai_ns_min;
-		i8253_cascade_ns_to_timer(devpriv->i8254_osc_base, div1, div2,
+		i8253_cascade_ns_to_timer(devpriv->i8254_osc_base,
+					  div1, div2,
 					  tim2, flags & TRIG_ROUND_NEAREST);
 		break;
 	case 2:
@@ -1277,9 +1278,9 @@ static int pci9118_ai_cmdtest(struct comedi_device *dev,
 
 	if (cmd->scan_begin_src == TRIG_TIMER) {
 		tmp = cmd->scan_begin_arg;
-		i8253_cascade_ns_to_timer(devpriv->i8254_osc_base, &divisor1,
-					  &divisor2, &cmd->scan_begin_arg,
-					  cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(devpriv->i8254_osc_base,
+					  &divisor1, &divisor2,
+					  &cmd->scan_begin_arg, cmd->flags);
 		if (cmd->scan_begin_arg < this_board->ai_ns_min)
 			cmd->scan_begin_arg = this_board->ai_ns_min;
 		if (tmp != cmd->scan_begin_arg)
@@ -1288,9 +1289,9 @@ static int pci9118_ai_cmdtest(struct comedi_device *dev,
 
 	if (cmd->convert_src & (TRIG_TIMER | TRIG_NOW)) {
 		tmp = cmd->convert_arg;
-		i8253_cascade_ns_to_timer(devpriv->i8254_osc_base, &divisor1,
-					  &divisor2, &cmd->convert_arg,
-					  cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(devpriv->i8254_osc_base,
+					  &divisor1, &divisor2,
+					  &cmd->convert_arg, cmd->flags);
 		if (cmd->convert_arg < this_board->ai_ns_min)
 			cmd->convert_arg = this_board->ai_ns_min;
 		if (tmp != cmd->convert_arg)
@@ -2086,7 +2087,7 @@ static int pci9118_common_attach(struct comedi_device *dev, int disable_irq,
 	s->insn_bits = pci9118_insn_bits_do;
 
 	devpriv->valid = 1;
-	devpriv->i8254_osc_base = 250;	/* 250ns=4MHz */
+	devpriv->i8254_osc_base = I8254_OSC_BASE_4MHZ;
 	devpriv->ai_maskharderr = 0x10a;
 					/* default measure crash condition */
 	if (hw_err_mask)		/* disable some requested */
diff --git a/drivers/staging/comedi/drivers/adv_pci1710.c b/drivers/staging/comedi/drivers/adv_pci1710.c
index 3dacfaeca4cb..49b39ec22708 100644
--- a/drivers/staging/comedi/drivers/adv_pci1710.c
+++ b/drivers/staging/comedi/drivers/adv_pci1710.c
@@ -1005,9 +1005,10 @@ static int pci171x_ai_docmd_and_mode(int mode, struct comedi_device *dev,
 		} else {
 			devpriv->ai_et = 0;
 		}
-		i8253_cascade_ns_to_timer(devpriv->i8254_osc_base, &divisor1,
-					  &divisor2, &devpriv->ai_timer1,
-					  devpriv->ai_flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(devpriv->i8254_osc_base,
+					  &divisor1, &divisor2,
+					  &devpriv->ai_timer1,
+					  devpriv->ai_flags);
 		outw(devpriv->CntrlReg, dev->iobase + PCI171x_CONTROL);
 		if (mode != 2) {
 			/*  start pacer */
@@ -1086,9 +1087,9 @@ static int pci171x_ai_cmdtest(struct comedi_device *dev,
 
 	if (cmd->convert_src == TRIG_TIMER) {
 		tmp = cmd->convert_arg;
-		i8253_cascade_ns_to_timer(devpriv->i8254_osc_base, &divisor1,
-					  &divisor2, &cmd->convert_arg,
-					  cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(devpriv->i8254_osc_base,
+					  &divisor1, &divisor2,
+					  &cmd->convert_arg, cmd->flags);
 		if (cmd->convert_arg < this_board->ai_ns_min)
 			cmd->convert_arg = this_board->ai_ns_min;
 		if (tmp != cmd->convert_arg)
@@ -1284,7 +1285,7 @@ static int pci1710_auto_attach(struct comedi_device *dev,
 			s->do_cmdtest = pci171x_ai_cmdtest;
 			s->do_cmd = pci171x_ai_cmd;
 		}
-		devpriv->i8254_osc_base = 100;	/*  100ns=10MHz */
+		devpriv->i8254_osc_base = I8254_OSC_BASE_10MHZ;
 		subdev++;
 	}
 
diff --git a/drivers/staging/comedi/drivers/amplc_pci224.c b/drivers/staging/comedi/drivers/amplc_pci224.c
index 179de53a86f0..cf385b8e32bf 100644
--- a/drivers/staging/comedi/drivers/amplc_pci224.c
+++ b/drivers/staging/comedi/drivers/amplc_pci224.c
@@ -215,12 +215,6 @@ Caveats:
 #define CLK_EXT		7	/* external clock */
 /* Macro to construct clock input configuration register value. */
 #define CLK_CONFIG(chan, src)	((((chan) & 3) << 3) | ((src) & 7))
-/* Timebases in ns. */
-#define TIMEBASE_10MHZ		100
-#define TIMEBASE_1MHZ		1000
-#define TIMEBASE_100KHZ		10000
-#define TIMEBASE_10KHZ		100000
-#define TIMEBASE_1KHZ		1000000
 
 /*
  * Counter/timer gate input configuration sources.
@@ -843,26 +837,26 @@ pci224_ao_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 		switch (round_mode) {
 		case TRIG_ROUND_NEAREST:
 		default:
-			round = TIMEBASE_10MHZ / 2;
+			round = I8254_OSC_BASE_10MHZ / 2;
 			break;
 		case TRIG_ROUND_DOWN:
 			round = 0;
 			break;
 		case TRIG_ROUND_UP:
-			round = TIMEBASE_10MHZ - 1;
+			round = I8254_OSC_BASE_10MHZ - 1;
 			break;
 		}
 		/* Be careful to avoid overflow! */
-		div2 = cmd->scan_begin_arg / TIMEBASE_10MHZ;
-		div2 += (round + cmd->scan_begin_arg % TIMEBASE_10MHZ) /
-		    TIMEBASE_10MHZ;
+		div2 = cmd->scan_begin_arg / I8254_OSC_BASE_10MHZ;
+		div2 += (round + cmd->scan_begin_arg % I8254_OSC_BASE_10MHZ) /
+			I8254_OSC_BASE_10MHZ;
 		if (div2 <= 0x10000) {
 			/* A single timer will suffice. */
 			if (div2 < 2)
 				div2 = 2;
-			cmd->scan_begin_arg = div2 * TIMEBASE_10MHZ;
+			cmd->scan_begin_arg = div2 * I8254_OSC_BASE_10MHZ;
 			if (cmd->scan_begin_arg < div2 ||
-			    cmd->scan_begin_arg < TIMEBASE_10MHZ) {
+			    cmd->scan_begin_arg < I8254_OSC_BASE_10MHZ) {
 				/* Overflow! */
 				cmd->scan_begin_arg = MAX_SCAN_PERIOD;
 			}
@@ -870,7 +864,8 @@ pci224_ao_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 			/* Use two timers. */
 			div1 = devpriv->cached_div1;
 			div2 = devpriv->cached_div2;
-			pci224_cascade_ns_to_timer(TIMEBASE_10MHZ, &div1, &div2,
+			pci224_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
+						   &div1, &div2,
 						   &cmd->scan_begin_arg,
 						   round_mode);
 			devpriv->cached_div1 = div1;
@@ -1002,19 +997,19 @@ static int pci224_ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 		switch (round_mode) {
 		case TRIG_ROUND_NEAREST:
 		default:
-			round = TIMEBASE_10MHZ / 2;
+			round = I8254_OSC_BASE_10MHZ / 2;
 			break;
 		case TRIG_ROUND_DOWN:
 			round = 0;
 			break;
 		case TRIG_ROUND_UP:
-			round = TIMEBASE_10MHZ - 1;
+			round = I8254_OSC_BASE_10MHZ - 1;
 			break;
 		}
 		/* Be careful to avoid overflow! */
-		div2 = cmd->scan_begin_arg / TIMEBASE_10MHZ;
-		div2 += (round + cmd->scan_begin_arg % TIMEBASE_10MHZ) /
-		    TIMEBASE_10MHZ;
+		div2 = cmd->scan_begin_arg / I8254_OSC_BASE_10MHZ;
+		div2 += (round + cmd->scan_begin_arg % I8254_OSC_BASE_10MHZ) /
+			I8254_OSC_BASE_10MHZ;
 		if (div2 <= 0x10000) {
 			/* A single timer will suffice. */
 			if (div2 < 2)
@@ -1025,7 +1020,8 @@ static int pci224_ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 			/* Use two timers. */
 			div1 = devpriv->cached_div1;
 			div2 = devpriv->cached_div2;
-			pci224_cascade_ns_to_timer(TIMEBASE_10MHZ, &div1, &div2,
+			pci224_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
+						   &div1, &div2,
 						   &ns, round_mode);
 		}
 
diff --git a/drivers/staging/comedi/drivers/cb_das16_cs.c b/drivers/staging/comedi/drivers/cb_das16_cs.c
index 3e072955ea79..64d5f291553f 100644
--- a/drivers/staging/comedi/drivers/cb_das16_cs.c
+++ b/drivers/staging/comedi/drivers/cb_das16_cs.c
@@ -234,9 +234,9 @@ static int das16cs_ai_cmdtest(struct comedi_device *dev,
 		unsigned int div1 = 0, div2 = 0;
 
 		tmp = cmd->scan_begin_arg;
-		i8253_cascade_ns_to_timer(100, &div1, &div2,
-					  &cmd->scan_begin_arg,
-					  cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
+					  &div1, &div2,
+					  &cmd->scan_begin_arg, cmd->flags);
 		if (tmp != cmd->scan_begin_arg)
 			err++;
 	}
@@ -244,9 +244,9 @@ static int das16cs_ai_cmdtest(struct comedi_device *dev,
 		unsigned int div1 = 0, div2 = 0;
 
 		tmp = cmd->convert_arg;
-		i8253_cascade_ns_to_timer(100, &div1, &div2,
-					  &cmd->scan_begin_arg,
-					  cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
+					  &div1, &div2,
+					  &cmd->scan_begin_arg, cmd->flags);
 		if (tmp != cmd->convert_arg)
 			err++;
 		if (cmd->scan_begin_src == TRIG_TIMER &&
diff --git a/drivers/staging/comedi/drivers/cb_pcidas.c b/drivers/staging/comedi/drivers/cb_pcidas.c
index 41d89ee7fa33..0891659f9eb5 100644
--- a/drivers/staging/comedi/drivers/cb_pcidas.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas.c
@@ -73,7 +73,6 @@ analog triggering on 1602 series
 #include "amcc_s5933.h"
 #include "comedi_fc.h"
 
-#define TIMER_BASE		100	/* 10MHz master clock */
 #define AI_BUFFER_SIZE		1024	/* max ai fifo size */
 #define AO_BUFFER_SIZE		1024	/* max ao fifo size */
 #define NUM_CHANNELS_8800	8
@@ -880,21 +879,19 @@ static int cb_pcidas_ai_cmdtest(struct comedi_device *dev,
 
 	if (cmd->scan_begin_src == TRIG_TIMER) {
 		tmp = cmd->scan_begin_arg;
-		i8253_cascade_ns_to_timer_2div(TIMER_BASE,
-					       &(devpriv->divisor1),
-					       &(devpriv->divisor2),
-					       &(cmd->scan_begin_arg),
-					       cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
+					  &devpriv->divisor1,
+					  &devpriv->divisor2,
+					  &cmd->scan_begin_arg, cmd->flags);
 		if (tmp != cmd->scan_begin_arg)
 			err++;
 	}
 	if (cmd->convert_src == TRIG_TIMER) {
 		tmp = cmd->convert_arg;
-		i8253_cascade_ns_to_timer_2div(TIMER_BASE,
-					       &(devpriv->divisor1),
-					       &(devpriv->divisor2),
-					       &(cmd->convert_arg),
-					       cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
+					  &devpriv->divisor1,
+					  &devpriv->divisor2,
+					  &cmd->convert_arg, cmd->flags);
 		if (tmp != cmd->convert_arg)
 			err++;
 	}
@@ -932,9 +929,9 @@ static void cb_pcidas_load_counters(struct comedi_device *dev, unsigned int *ns,
 {
 	struct cb_pcidas_private *devpriv = dev->private;
 
-	i8253_cascade_ns_to_timer_2div(TIMER_BASE, &(devpriv->divisor1),
-				       &(devpriv->divisor2), ns,
-				       rounding_flags & TRIG_ROUND_MASK);
+	i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
+				  &devpriv->divisor1, &devpriv->divisor2,
+				  ns, rounding_flags);
 
 	/* Write the values of ctr1 and ctr2 into counters 1 and 2 */
 	i8254_load(devpriv->pacer_counter_dio + ADC8254, 0, 1,
@@ -1084,11 +1081,10 @@ static int cb_pcidas_ao_cmdtest(struct comedi_device *dev,
 
 	if (cmd->scan_begin_src == TRIG_TIMER) {
 		tmp = cmd->scan_begin_arg;
-		i8253_cascade_ns_to_timer_2div(TIMER_BASE,
-					       &(devpriv->ao_divisor1),
-					       &(devpriv->ao_divisor2),
-					       &(cmd->scan_begin_arg),
-					       cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
+					  &devpriv->ao_divisor1,
+					  &devpriv->ao_divisor2,
+					  &cmd->scan_begin_arg, cmd->flags);
 		if (tmp != cmd->scan_begin_arg)
 			err++;
 	}
@@ -1209,11 +1205,10 @@ static int cb_pcidas_ao_cmd(struct comedi_device *dev,
 
 	/*  load counters */
 	if (cmd->scan_begin_src == TRIG_TIMER) {
-		i8253_cascade_ns_to_timer_2div(TIMER_BASE,
-					       &(devpriv->ao_divisor1),
-					       &(devpriv->ao_divisor2),
-					       &(cmd->scan_begin_arg),
-					       cmd->flags);
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
+					  &devpriv->ao_divisor1,
+					  &devpriv->ao_divisor2,
+					  &cmd->scan_begin_arg, cmd->flags);
 
 		/* Write the values of ctr1 and ctr2 into counters 1 and 2 */
 		i8254_load(devpriv->pacer_counter_dio + DAC8254, 0, 1,
diff --git a/drivers/staging/comedi/drivers/das16.c b/drivers/staging/comedi/drivers/das16.c
index fc058f8e8702..30f3995d7297 100644
--- a/drivers/staging/comedi/drivers/das16.c
+++ b/drivers/staging/comedi/drivers/das16.c
@@ -675,21 +675,19 @@ static int das16_cmd_test(struct comedi_device *dev, struct comedi_subdevice *s,
 	if (cmd->scan_begin_src == TRIG_TIMER) {
 		unsigned int tmp = cmd->scan_begin_arg;
 		/*  set divisors, correct timing arguments */
-		i8253_cascade_ns_to_timer_2div(devpriv->clockbase,
-					       &devpriv->divisor1,
-					       &devpriv->divisor2,
-					       &cmd->scan_begin_arg,
-					       cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(devpriv->clockbase,
+					  &devpriv->divisor1,
+					  &devpriv->divisor2,
+					  &cmd->scan_begin_arg, cmd->flags);
 		err += (tmp != cmd->scan_begin_arg);
 	}
 	if (cmd->convert_src == TRIG_TIMER) {
 		unsigned int tmp = cmd->convert_arg;
 		/*  set divisors, correct timing arguments */
-		i8253_cascade_ns_to_timer_2div(devpriv->clockbase,
-					       &devpriv->divisor1,
-					       &devpriv->divisor2,
-					       &cmd->convert_arg,
-					       cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(devpriv->clockbase,
+					  &devpriv->divisor1,
+					  &devpriv->divisor2,
+					  &cmd->convert_arg, cmd->flags);
 		err += (tmp != cmd->convert_arg);
 	}
 	if (err)
@@ -725,11 +723,9 @@ static unsigned int das16_set_pacer(struct comedi_device *dev, unsigned int ns,
 	struct das16_private_struct *devpriv = dev->private;
 	unsigned long timer_base = dev->iobase + DAS16_TIMER_BASE_REG;
 
-	i8253_cascade_ns_to_timer_2div(devpriv->clockbase,
-				       &devpriv->divisor1,
-				       &devpriv->divisor2,
-				       &ns,
-				       rounding_flags & TRIG_ROUND_MASK);
+	i8253_cascade_ns_to_timer(devpriv->clockbase,
+				  &devpriv->divisor1, &devpriv->divisor2,
+				  &ns, rounding_flags);
 
 	/* Write the values of ctr1 and ctr2 into counters 1 and 2 */
 	i8254_load(timer_base, 0, 1, devpriv->divisor1, 2);
@@ -1036,14 +1032,15 @@ static int das16_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 		status = inb(dev->iobase + DAS1600_STATUS_REG);
 
 		if (status & DAS1600_STATUS_CLK_10MHZ)
-			devpriv->clockbase = 100;
+			devpriv->clockbase = I8254_OSC_BASE_10MHZ;
 		else
-			devpriv->clockbase = 1000;
+			devpriv->clockbase = I8254_OSC_BASE_1MHZ;
 	} else {
 		if (it->options[3])
-			devpriv->clockbase = 1000 / it->options[3];
+			devpriv->clockbase = I8254_OSC_BASE_1MHZ /
+					     it->options[3];
 		else
-			devpriv->clockbase = 1000;	/*  1 MHz default */
+			devpriv->clockbase = I8254_OSC_BASE_1MHZ;
 	}
 
 	/* initialize dma */
diff --git a/drivers/staging/comedi/drivers/das16m1.c b/drivers/staging/comedi/drivers/das16m1.c
index 187b0a1c378b..579b74e471d9 100644
--- a/drivers/staging/comedi/drivers/das16m1.c
+++ b/drivers/staging/comedi/drivers/das16m1.c
@@ -63,8 +63,6 @@ irq can be omitted, although the cmd interface will not work without it.
 #define DAS16M1_SIZE 16
 #define DAS16M1_SIZE2 8
 
-#define DAS16M1_XTAL 100	/* 10 MHz master clock */
-
 #define FIFO_SIZE 1024		/*  1024 sample fifo */
 
 /*
@@ -207,11 +205,10 @@ static int das16m1_cmd_test(struct comedi_device *dev,
 	if (cmd->convert_src == TRIG_TIMER) {
 		tmp = cmd->convert_arg;
 		/* calculate counter values that give desired timing */
-		i8253_cascade_ns_to_timer_2div(DAS16M1_XTAL,
-					       &(devpriv->divisor1),
-					       &(devpriv->divisor2),
-					       &(cmd->convert_arg),
-					       cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
+					  &devpriv->divisor1,
+					  &devpriv->divisor2,
+					  &cmd->convert_arg, cmd->flags);
 		if (tmp != cmd->convert_arg)
 			err++;
 	}
@@ -250,9 +247,10 @@ static unsigned int das16m1_set_pacer(struct comedi_device *dev,
 {
 	struct das16m1_private_struct *devpriv = dev->private;
 
-	i8253_cascade_ns_to_timer_2div(DAS16M1_XTAL, &(devpriv->divisor1),
-				       &(devpriv->divisor2), &ns,
-				       rounding_flags & TRIG_ROUND_MASK);
+	i8253_cascade_ns_to_timer_2div(I8254_OSC_BASE_10MHZ,
+				       &devpriv->divisor1,
+				       &devpriv->divisor2,
+				       &ns, rounding_flags);
 
 	/* Write the values of ctr1 and ctr2 into counters 1 and 2 */
 	i8254_load(dev->iobase + DAS16M1_8254_SECOND, 0, 1, devpriv->divisor1,
diff --git a/drivers/staging/comedi/drivers/das1800.c b/drivers/staging/comedi/drivers/das1800.c
index 8b9a0a66b5a5..f753a10c6549 100644
--- a/drivers/staging/comedi/drivers/das1800.c
+++ b/drivers/staging/comedi/drivers/das1800.c
@@ -108,7 +108,6 @@ TODO:
 /* misc. defines */
 #define DAS1800_SIZE           16	/* uses 16 io addresses */
 #define FIFO_SIZE              1024	/*  1024 sample fifo */
-#define TIMER_BASE             200	/*  5 Mhz master clock */
 #define UNIPOLAR               0x4	/*  bit that determines whether input range is uni/bipolar */
 #define DMA_BUF_SIZE           0x1ff00	/*  size in bytes of dma buffers */
 
@@ -839,12 +838,11 @@ static int das1800_ai_do_cmdtest(struct comedi_device *dev,
 		if (cmd->scan_begin_src == TRIG_FOLLOW) {
 			tmp_arg = cmd->convert_arg;
 			/* calculate counter values that give desired timing */
-			i8253_cascade_ns_to_timer_2div(TIMER_BASE,
-						       &(devpriv->divisor1),
-						       &(devpriv->divisor2),
-						       &(cmd->convert_arg),
-						       cmd->
-						       flags & TRIG_ROUND_MASK);
+			i8253_cascade_ns_to_timer(I8254_OSC_BASE_5MHZ,
+						  &devpriv->divisor1,
+						  &devpriv->divisor2,
+						  &cmd->convert_arg,
+						  cmd->flags);
 			if (tmp_arg != cmd->convert_arg)
 				err++;
 		}
@@ -869,16 +867,11 @@ static int das1800_ai_do_cmdtest(struct comedi_device *dev,
 				}
 				tmp_arg = cmd->scan_begin_arg;
 				/* calculate counter values that give desired timing */
-				i8253_cascade_ns_to_timer_2div(TIMER_BASE,
-							       &(devpriv->
-								 divisor1),
-							       &(devpriv->
-								 divisor2),
-							       &(cmd->
-								 scan_begin_arg),
-							       cmd->
-							       flags &
-							       TRIG_ROUND_MASK);
+				i8253_cascade_ns_to_timer(I8254_OSC_BASE_5MHZ,
+							  &devpriv->divisor1,
+							  &devpriv->divisor2,
+							  &cmd->scan_begin_arg,
+							  cmd->flags);
 				if (tmp_arg != cmd->scan_begin_arg)
 					err++;
 			}
@@ -1010,12 +1003,10 @@ static int setup_counters(struct comedi_device *dev,
 		if (cmd->convert_src == TRIG_TIMER) {
 			/* set conversion frequency */
 			period = cmd->convert_arg;
-			i8253_cascade_ns_to_timer_2div(TIMER_BASE,
-						       &devpriv->divisor1,
-						       &devpriv->divisor2,
-						       &period,
-						       cmd->flags &
-							TRIG_ROUND_MASK);
+			i8253_cascade_ns_to_timer(I8254_OSC_BASE_5MHZ,
+						  &devpriv->divisor1,
+						  &devpriv->divisor2,
+						  &period, cmd->flags);
 			if (das1800_set_frequency(dev) < 0)
 				return -1;
 		}
@@ -1023,9 +1014,10 @@ static int setup_counters(struct comedi_device *dev,
 	case TRIG_TIMER:	/*  in burst mode */
 		/* set scan frequency */
 		period = cmd->scan_begin_arg;
-		i8253_cascade_ns_to_timer_2div(TIMER_BASE, &devpriv->divisor1,
-					       &devpriv->divisor2, &period,
-					       cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_5MHZ,
+					  &devpriv->divisor1,
+					  &devpriv->divisor2,
+					  &period, cmd->flags);
 		if (das1800_set_frequency(dev) < 0)
 			return -1;
 		break;
diff --git a/drivers/staging/comedi/drivers/das800.c b/drivers/staging/comedi/drivers/das800.c
index b80dd0362ffc..5af0a5764a8c 100644
--- a/drivers/staging/comedi/drivers/das800.c
+++ b/drivers/staging/comedi/drivers/das800.c
@@ -66,7 +66,6 @@ cmd triggers supported:
 #include "comedi_fc.h"
 
 #define DAS800_SIZE           8
-#define TIMER_BASE            1000
 #define N_CHAN_AI             8	/*  number of analog input channels */
 
 /* Registers for the das800 */
@@ -356,11 +355,10 @@ static int das800_ai_do_cmdtest(struct comedi_device *dev,
 		int tmp = cmd->convert_arg;
 
 		/* calculate counter values that give desired timing */
-		i8253_cascade_ns_to_timer_2div(TIMER_BASE,
-					       &devpriv->divisor1,
-					       &devpriv->divisor2,
-					       &cmd->convert_arg,
-					       cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_1MHZ,
+					  &devpriv->divisor1,
+					  &devpriv->divisor2,
+					  &cmd->convert_arg, cmd->flags);
 		if (tmp != cmd->convert_arg)
 			err++;
 	}
diff --git a/drivers/staging/comedi/drivers/ni_labpc.c b/drivers/staging/comedi/drivers/ni_labpc.c
index 27daccb78f83..e91570dd6b0d 100644
--- a/drivers/staging/comedi/drivers/ni_labpc.c
+++ b/drivers/staging/comedi/drivers/ni_labpc.c
@@ -73,7 +73,6 @@
 #include "ni_labpc_isadma.h"
 
 #define LABPC_SIZE		0x20	/* size of ISA io region */
-#define LABPC_TIMER_BASE	500	/* 2 MHz master clock */
 #define LABPC_ADC_TIMEOUT	1000
 
 enum scan_mode {
@@ -459,13 +458,13 @@ static void labpc_adc_timing(struct comedi_device *dev, struct comedi_cmd *cmd,
 		 * clock speed on convert and scan counters)
 		 */
 		devpriv->divisor_b0 = (scan_period - 1) /
-		    (LABPC_TIMER_BASE * max_counter_value) + 1;
+		    (I8254_OSC_BASE_2MHZ * max_counter_value) + 1;
 		if (devpriv->divisor_b0 < min_counter_value)
 			devpriv->divisor_b0 = min_counter_value;
 		if (devpriv->divisor_b0 > max_counter_value)
 			devpriv->divisor_b0 = max_counter_value;
 
-		base_period = LABPC_TIMER_BASE * devpriv->divisor_b0;
+		base_period = I8254_OSC_BASE_2MHZ * devpriv->divisor_b0;
 
 		/*  set a0 for conversion frequency and b1 for scan frequency */
 		switch (cmd->flags & TRIG_ROUND_MASK) {
@@ -510,22 +509,20 @@ static void labpc_adc_timing(struct comedi_device *dev, struct comedi_cmd *cmd,
 		 * calculate cascaded counter values
 		 * that give desired scan timing
 		 */
-		i8253_cascade_ns_to_timer_2div(LABPC_TIMER_BASE,
-					       &(devpriv->divisor_b1),
-					       &(devpriv->divisor_b0),
-					       &scan_period,
-					       cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_2MHZ,
+					  &devpriv->divisor_b1,
+					  &devpriv->divisor_b0,
+					  &scan_period, cmd->flags);
 		labpc_set_ai_scan_period(cmd, mode, scan_period);
 	} else if (convert_period) {
 		/*
 		 * calculate cascaded counter values
 		 * that give desired conversion timing
 		 */
-		i8253_cascade_ns_to_timer_2div(LABPC_TIMER_BASE,
-					       &(devpriv->divisor_a0),
-					       &(devpriv->divisor_b0),
-					       &convert_period,
-					       cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_2MHZ,
+					  &devpriv->divisor_a0,
+					  &devpriv->divisor_b0,
+					  &convert_period, cmd->flags);
 		labpc_set_ai_convert_period(cmd, mode, convert_period);
 	}
 }
diff --git a/drivers/staging/comedi/drivers/pcl711.c b/drivers/staging/comedi/drivers/pcl711.c
index e170f8aeef5f..89982fb52e50 100644
--- a/drivers/staging/comedi/drivers/pcl711.c
+++ b/drivers/staging/comedi/drivers/pcl711.c
@@ -349,11 +349,11 @@ static int pcl711_ai_cmdtest(struct comedi_device *dev,
 
 	if (cmd->scan_begin_src == TRIG_TIMER) {
 		tmp = cmd->scan_begin_arg;
-		i8253_cascade_ns_to_timer(500,		/* 2 Mhz */
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_2MHZ,
 					  &devpriv->divisor1,
 					  &devpriv->divisor2,
 					  &cmd->scan_begin_arg,
-					  cmd->flags & TRIG_ROUND_MASK);
+					  cmd->flags);
 		if (tmp != cmd->scan_begin_arg)
 			err++;
 	}
diff --git a/drivers/staging/comedi/drivers/pcl812.c b/drivers/staging/comedi/drivers/pcl812.c
index 2b10a95251bd..530aee14f07a 100644
--- a/drivers/staging/comedi/drivers/pcl812.c
+++ b/drivers/staging/comedi/drivers/pcl812.c
@@ -589,9 +589,9 @@ static int pcl812_ai_cmdtest(struct comedi_device *dev,
 
 	if (cmd->convert_src == TRIG_TIMER) {
 		tmp = cmd->convert_arg;
-		i8253_cascade_ns_to_timer(board->i8254_osc_base, &divisor1,
-					  &divisor2, &cmd->convert_arg,
-					  cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(board->i8254_osc_base,
+					  &divisor1, &divisor2,
+					  &cmd->convert_arg, cmd->flags);
 		if (cmd->convert_arg < board->ai_ns_min)
 			cmd->convert_arg = board->ai_ns_min;
 		if (tmp != cmd->convert_arg)
@@ -637,8 +637,7 @@ static int pcl812_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 			cmd->convert_arg = board->ai_ns_min;
 		i8253_cascade_ns_to_timer(board->i8254_osc_base,
 					  &divisor1, &divisor2,
-					  &cmd->convert_arg,
-					  cmd->flags & TRIG_ROUND_MASK);
+					  &cmd->convert_arg, cmd->flags);
 	}
 
 	start_pacer(dev, -1, 0, 0);	/*  stop pacer */
@@ -1440,40 +1439,40 @@ static void pcl812_detach(struct comedi_device *dev)
 
 static const struct pcl812_board boardtypes[] = {
 	{"pcl812", boardPCL812, 16, 0, 2, 16, 16, 0x0fff,
-	 33000, 500, &range_bipolar10, &range_unipolar5,
+	 33000, I8254_OSC_BASE_2MHZ, &range_bipolar10, &range_unipolar5,
 	 0xdcfc, 0x0a, PCLx1x_IORANGE, 0},
 	{"pcl812pg", boardPCL812PG, 16, 0, 2, 16, 16, 0x0fff,
-	 33000, 500, &range_pcl812pg_ai, &range_unipolar5,
+	 33000, I8254_OSC_BASE_2MHZ, &range_pcl812pg_ai, &range_unipolar5,
 	 0xdcfc, 0x0a, PCLx1x_IORANGE, 0},
 	{"acl8112pg", boardPCL812PG, 16, 0, 2, 16, 16, 0x0fff,
-	 10000, 500, &range_pcl812pg_ai, &range_unipolar5,
+	 10000, I8254_OSC_BASE_2MHZ, &range_pcl812pg_ai, &range_unipolar5,
 	 0xdcfc, 0x0a, PCLx1x_IORANGE, 0},
 	{"acl8112dg", boardACL8112, 16, 8, 2, 16, 16, 0x0fff,
-	 10000, 500, &range_acl8112dg_ai, &range_unipolar5,
+	 10000, I8254_OSC_BASE_2MHZ, &range_acl8112dg_ai, &range_unipolar5,
 	 0xdcfc, 0x0a, PCLx1x_IORANGE, 1},
 	{"acl8112hg", boardACL8112, 16, 8, 2, 16, 16, 0x0fff,
-	 10000, 500, &range_acl8112hg_ai, &range_unipolar5,
+	 10000, I8254_OSC_BASE_2MHZ, &range_acl8112hg_ai, &range_unipolar5,
 	 0xdcfc, 0x0a, PCLx1x_IORANGE, 1},
 	{"a821pgl", boardA821, 16, 8, 1, 16, 16, 0x0fff,
-	 10000, 500, &range_pcl813b_ai, &range_unipolar5,
+	 10000, I8254_OSC_BASE_2MHZ, &range_pcl813b_ai, &range_unipolar5,
 	 0x000c, 0x00, PCLx1x_IORANGE, 0},
 	{"a821pglnda", boardA821, 16, 8, 0, 0, 0, 0x0fff,
-	 10000, 500, &range_pcl813b_ai, NULL,
+	 10000, I8254_OSC_BASE_2MHZ, &range_pcl813b_ai, NULL,
 	 0x000c, 0x00, PCLx1x_IORANGE, 0},
 	{"a821pgh", boardA821, 16, 8, 1, 16, 16, 0x0fff,
-	 10000, 500, &range_a821pgh_ai, &range_unipolar5,
+	 10000, I8254_OSC_BASE_2MHZ, &range_a821pgh_ai, &range_unipolar5,
 	 0x000c, 0x00, PCLx1x_IORANGE, 0},
 	{"a822pgl", boardACL8112, 16, 8, 2, 16, 16, 0x0fff,
-	 10000, 500, &range_acl8112dg_ai, &range_unipolar5,
+	 10000, I8254_OSC_BASE_2MHZ, &range_acl8112dg_ai, &range_unipolar5,
 	 0xdcfc, 0x0a, PCLx1x_IORANGE, 0},
 	{"a822pgh", boardACL8112, 16, 8, 2, 16, 16, 0x0fff,
-	 10000, 500, &range_acl8112hg_ai, &range_unipolar5,
+	 10000, I8254_OSC_BASE_2MHZ, &range_acl8112hg_ai, &range_unipolar5,
 	 0xdcfc, 0x0a, PCLx1x_IORANGE, 0},
 	{"a823pgl", boardACL8112, 16, 8, 2, 16, 16, 0x0fff,
-	 8000, 500, &range_acl8112dg_ai, &range_unipolar5,
+	 8000, I8254_OSC_BASE_2MHZ, &range_acl8112dg_ai, &range_unipolar5,
 	 0xdcfc, 0x0a, PCLx1x_IORANGE, 0},
 	{"a823pgh", boardACL8112, 16, 8, 2, 16, 16, 0x0fff,
-	 8000, 500, &range_acl8112hg_ai, &range_unipolar5,
+	 8000, I8254_OSC_BASE_2MHZ, &range_acl8112hg_ai, &range_unipolar5,
 	 0xdcfc, 0x0a, PCLx1x_IORANGE, 0},
 	{"pcl813", boardPCL813, 32, 0, 0, 0, 0, 0x0fff,
 	 0, 0, &range_pcl813b_ai, NULL,
@@ -1488,10 +1487,10 @@ static const struct pcl812_board boardtypes[] = {
 	 0, 0, &range_iso813_1_ai, NULL,
 	 0x0000, 0x00, PCLx1x_IORANGE, 0},
 	{"acl8216", boardACL8216, 16, 8, 2, 16, 16, 0xffff,
-	 10000, 500, &range_pcl813b2_ai, &range_unipolar5,
+	 10000, I8254_OSC_BASE_2MHZ, &range_pcl813b2_ai, &range_unipolar5,
 	 0xdcfc, 0x0a, PCLx1x_IORANGE, 1},
 	{"a826pg", boardACL8216, 16, 8, 2, 16, 16, 0xffff,
-	 10000, 500, &range_pcl813b2_ai, &range_unipolar5,
+	 10000, I8254_OSC_BASE_2MHZ, &range_pcl813b2_ai, &range_unipolar5,
 	 0xdcfc, 0x0a, PCLx1x_IORANGE, 0},
 };
 
diff --git a/drivers/staging/comedi/drivers/pcl816.c b/drivers/staging/comedi/drivers/pcl816.c
index f03134962596..2fd9b178e0c6 100644
--- a/drivers/staging/comedi/drivers/pcl816.c
+++ b/drivers/staging/comedi/drivers/pcl816.c
@@ -481,8 +481,7 @@ static int pcl816_ai_cmdtest(struct comedi_device *dev,
 		tmp = cmd->convert_arg;
 		i8253_cascade_ns_to_timer(board->i8254_osc_base,
 					  &divisor1, &divisor2,
-					  &cmd->convert_arg,
-					  cmd->flags & TRIG_ROUND_MASK);
+					  &cmd->convert_arg, cmd->flags);
 		if (cmd->convert_arg < board->ai_ns_min)
 			cmd->convert_arg = board->ai_ns_min;
 		if (tmp != cmd->convert_arg)
@@ -528,9 +527,9 @@ static int pcl816_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 		if (cmd->convert_arg < board->ai_ns_min)
 			cmd->convert_arg = board->ai_ns_min;
 
-		i8253_cascade_ns_to_timer(board->i8254_osc_base, &divisor1,
-					  &divisor2, &cmd->convert_arg,
-					  cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(board->i8254_osc_base,
+					  &divisor1, &divisor2,
+					  &cmd->convert_arg, cmd->flags);
 
 		/*  PCL816 crash if any divisor is set to 1 */
 		if (divisor1 == 1) {
@@ -1105,7 +1104,7 @@ static const struct pcl816_board boardtypes[] = {
 	 0xffff,		/*  D/A maxdata */
 	 1024,
 	 1,			/*  ao chan list */
-	 100},
+	 I8254_OSC_BASE_10MHZ},
 	{"pcl814b", 8, 16, 10000, 1, 16, 16, &range_pcl816,
 	 &range_pcl816, PCLx1x_RANGE,
 	 0x00fc,
@@ -1114,7 +1113,7 @@ static const struct pcl816_board boardtypes[] = {
 	 0x3fff,
 	 1024,
 	 1,
-	 100},
+	 I8254_OSC_BASE_10MHZ},
 };
 
 static struct comedi_driver pcl816_driver = {
diff --git a/drivers/staging/comedi/drivers/pcl818.c b/drivers/staging/comedi/drivers/pcl818.c
index 33cd4aae884e..7be0c946bd7c 100644
--- a/drivers/staging/comedi/drivers/pcl818.c
+++ b/drivers/staging/comedi/drivers/pcl818.c
@@ -800,8 +800,9 @@ static int pcl818_ai_cmd_mode(int mode, struct comedi_device *dev,
 		devpriv->neverending_ai = 1;	/* well, user want neverending */
 
 	if (mode == 1) {
-		i8253_cascade_ns_to_timer(devpriv->i8253_osc_base, &divisor1,
-					  &divisor2, &cmd->convert_arg,
+		i8253_cascade_ns_to_timer(devpriv->i8253_osc_base,
+					  &divisor1, &divisor2,
+					  &cmd->convert_arg,
 					  TRIG_ROUND_NEAREST);
 		if (divisor1 == 1) {	/* PCL718/818 crash if any divisor is set to 1 */
 			divisor1 = 2;
@@ -1034,9 +1035,9 @@ static int ai_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 
 	if (cmd->convert_src == TRIG_TIMER) {
 		tmp = cmd->convert_arg;
-		i8253_cascade_ns_to_timer(devpriv->i8253_osc_base, &divisor1,
-					  &divisor2, &cmd->convert_arg,
-					  cmd->flags & TRIG_ROUND_MASK);
+		i8253_cascade_ns_to_timer(devpriv->i8253_osc_base,
+					  &divisor1, &divisor2,
+					  &cmd->convert_arg, cmd->flags);
 		if (cmd->convert_arg < board->ns_min)
 			cmd->convert_arg = board->ns_min;
 		if (tmp != cmd->convert_arg)
@@ -1432,9 +1433,9 @@ no_dma:
 
 	/* select 1/10MHz oscilator */
 	if ((it->options[3] == 0) || (it->options[3] == 10))
-		devpriv->i8253_osc_base = 100;
+		devpriv->i8253_osc_base = I8254_OSC_BASE_10MHZ;
 	else
-		devpriv->i8253_osc_base = 1000;
+		devpriv->i8253_osc_base = I8254_OSC_BASE_1MHZ;
 
 	/* max sampling speed */
 	devpriv->ns_min = board->ns_min;