staging: comedi: amplc_pci224: always cascade the 8254 timers

The 8254 timers are only used in this driver to generate the analog
output pacer. To simplify the driver, always cascade the timers.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/amplc_pci224.c

@@ -841,51 +841,15 @@ pci224_ao_cmdtest(struct comedi_device *dev, struct comedi_subdevice *s,
 	/* Step 4: fix up any arguments. */
 
 	if (cmd->scan_begin_src == TRIG_TIMER) {
-		unsigned int div1, div2, round;
-		int round_mode = cmd->flags & TRIG_ROUND_MASK;
-
 		tmp = cmd->scan_begin_arg;
-		/* Check whether to use a single timer. */
-		switch (round_mode) {
-		case TRIG_ROUND_NEAREST:
-		default:
-			round = I8254_OSC_BASE_10MHZ / 2;
-			break;
-		case TRIG_ROUND_DOWN:
-			round = 0;
-			break;
-		case TRIG_ROUND_UP:
-			round = I8254_OSC_BASE_10MHZ - 1;
-			break;
-		}
-		/* Be careful to avoid overflow! */
-		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 * I8254_OSC_BASE_10MHZ;
-			if (cmd->scan_begin_arg < div2 ||
-			    cmd->scan_begin_arg < I8254_OSC_BASE_10MHZ) {
-				/* Overflow! */
-				cmd->scan_begin_arg = MAX_SCAN_PERIOD;
-			}
-		} else {
-			/* Use two timers. */
-			div1 = devpriv->cached_div1;
-			div2 = devpriv->cached_div2;
-			i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
-						  &div1, &div2,
-						  &cmd->scan_begin_arg,
-						  round_mode);
-			devpriv->cached_div1 = div1;
-			devpriv->cached_div2 = div2;
-		}
+		/* Use two timers. */
+		i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
+					  &devpriv->cached_div1,
+					  &devpriv->cached_div2,
+					  &cmd->scan_begin_arg,
+					  cmd->flags);
 		if (tmp != cmd->scan_begin_arg)
 			err++;
-
 	}
 
 	if (err)
@@ -906,70 +870,33 @@ static void pci224_ao_start_pacer(struct comedi_device *dev,
 {
 	struct pci224_private *devpriv = dev->private;
 	struct comedi_cmd *cmd = &s->async->cmd;
-	unsigned int div1, div2, round;
-	unsigned int ns = cmd->scan_begin_arg;
-	int round_mode = cmd->flags & TRIG_ROUND_MASK;
 
-	/* Check whether to use a single timer. */
-	switch (round_mode) {
-	case TRIG_ROUND_NEAREST:
-	default:
-		round = I8254_OSC_BASE_10MHZ / 2;
-		break;
-	case TRIG_ROUND_DOWN:
-		round = 0;
-		break;
-	case TRIG_ROUND_UP:
-		round = I8254_OSC_BASE_10MHZ - 1;
-		break;
-	}
-	/* Be careful to avoid overflow! */
-	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;
-		div2 &= 0xffff;
-		div1 = 1;	/* Flag that single timer to be used. */
-	} else {
-		/* Use two timers. */
-		div1 = devpriv->cached_div1;
-		div2 = devpriv->cached_div2;
-		i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
-					 &div1, &div2,
-					 &ns, round_mode);
-	}
+	/* Use two timers. */
+	i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
+				  &devpriv->cached_div1,
+				  &devpriv->cached_div2,
+				  &cmd->scan_begin_arg,
+				  cmd->flags);
 
 	/*
 	 * The output of timer Z2-0 will be used as the scan trigger
 	 * source.
 	 */
 	/* Make sure Z2-0 is gated on.  */
-	outb(GAT_CONFIG(0, GAT_VCC),
-		devpriv->iobase1 + PCI224_ZGAT_SCE);
-	if (div1 == 1) {
-		/* Not cascading.  Z2-0 needs 10 MHz clock. */
-		outb(CLK_CONFIG(0, CLK_10MHZ),
-			devpriv->iobase1 + PCI224_ZCLK_SCE);
-	} else {
-		/* Cascading with Z2-2. */
-		/* Make sure Z2-2 is gated on.  */
-		outb(GAT_CONFIG(2, GAT_VCC),
-			devpriv->iobase1 + PCI224_ZGAT_SCE);
-		/* Z2-2 needs 10 MHz clock. */
-		outb(CLK_CONFIG(2, CLK_10MHZ),
-			devpriv->iobase1 + PCI224_ZCLK_SCE);
-		/* Load Z2-2 mode (2) and counter (div1). */
-		i8254_load(devpriv->iobase1 + PCI224_Z2_CT0, 0,
-				2, div1, 2);
-		/* Z2-0 is clocked from Z2-2's output. */
-		outb(CLK_CONFIG(0, CLK_OUTNM1),
-			devpriv->iobase1 + PCI224_ZCLK_SCE);
-	}
+	outb(GAT_CONFIG(0, GAT_VCC), devpriv->iobase1 + PCI224_ZGAT_SCE);
+	/* Cascading with Z2-2. */
+	/* Make sure Z2-2 is gated on.  */
+	outb(GAT_CONFIG(2, GAT_VCC), devpriv->iobase1 + PCI224_ZGAT_SCE);
+	/* Z2-2 needs 10 MHz clock. */
+	outb(CLK_CONFIG(2, CLK_10MHZ), devpriv->iobase1 + PCI224_ZCLK_SCE);
+	/* Load Z2-2 mode (2) and counter (div1). */
+	i8254_load(devpriv->iobase1 + PCI224_Z2_CT0, 0,
+			2, devpriv->cached_div1, 2);
+	/* Z2-0 is clocked from Z2-2's output. */
+	outb(CLK_CONFIG(0, CLK_OUTNM1), devpriv->iobase1 + PCI224_ZCLK_SCE);
 	/* Load Z2-0 mode (2) and counter (div2). */
-	i8254_load(devpriv->iobase1 + PCI224_Z2_CT0, 0, 0, div2, 2);
+	i8254_load(devpriv->iobase1 + PCI224_Z2_CT0, 0,
+		   0, devpriv->cached_div2, 2);
 }
 
 static int pci224_ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)