staging: comedi: pcm3724: tidy up register map defines

For aesthetics, rename the register map defines so they have namespace
associated with the driver and use the BIT macro to define the bits.

Add the missing defines for the registers and use them to remove the
magic values from the driver.

Add a comment about the extra registers to explain why this driver
doesn't just use the standard 8255 driver instead.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/pcm3724.c

@@ -27,19 +27,31 @@
 
 #include "8255.h"
 
-#define BUF_C0 0x1
-#define BUF_B0 0x2
-#define BUF_A0 0x4
-#define BUF_C1 0x8
-#define BUF_B1 0x10
-#define BUF_A1 0x20
-
-#define GATE_A0 0x4
-#define GATE_B0	0x2
-#define GATE_C0	0x1
-#define GATE_A1	0x20
-#define GATE_B1	0x10
-#define GATE_C1 0x8
+/*
+ * Register I/O Map
+ *
+ * This board has two standard 8255 devices that provide six 8-bit DIO ports
+ * (48 channels total). Six 74HCT245 chips (one for each port) buffer the
+ * I/O lines to increase driving capability. Because the 74HCT245 is a
+ * bidirectional, tri-state line buffer, two additional I/O ports are used
+ * to control the direction of data and the enable of each port.
+ */
+#define PCM3724_8255_0_BASE		0x00
+#define PCM3724_8255_1_BASE		0x04
+#define PCM3724_DIO_DIR_REG		0x08
+#define PCM3724_DIO_DIR_C0_OUT		BIT(0)
+#define PCM3724_DIO_DIR_B0_OUT		BIT(1)
+#define PCM3724_DIO_DIR_A0_OUT		BIT(2)
+#define PCM3724_DIO_DIR_C1_OUT		BIT(3)
+#define PCM3724_DIO_DIR_B1_OUT		BIT(4)
+#define PCM3724_DIO_DIR_A1_OUT		BIT(5)
+#define PCM3724_GATE_CTRL_REG		0x09
+#define PCM3724_GATE_CTRL_C0_ENA	BIT(0)
+#define PCM3724_GATE_CTRL_B0_ENA	BIT(1)
+#define PCM3724_GATE_CTRL_A0_ENA	BIT(2)
+#define PCM3724_GATE_CTRL_C1_ENA	BIT(3)
+#define PCM3724_GATE_CTRL_B1_ENA	BIT(4)
+#define PCM3724_GATE_CTRL_A1_ENA	BIT(5)
 
 /* used to track configured dios */
 struct priv_pcm3724 {
@@ -52,21 +64,21 @@ static int compute_buffer(int config, int devno, struct comedi_subdevice *s)
 	/* 1 in io_bits indicates output */
 	if (s->io_bits & 0x0000ff) {
 		if (devno == 0)
-			config |= BUF_A0;
+			config |= PCM3724_DIO_DIR_A0_OUT;
 		else
-			config |= BUF_A1;
+			config |= PCM3724_DIO_DIR_A1_OUT;
 	}
 	if (s->io_bits & 0x00ff00) {
 		if (devno == 0)
-			config |= BUF_B0;
+			config |= PCM3724_DIO_DIR_B0_OUT;
 		else
-			config |= BUF_B1;
+			config |= PCM3724_DIO_DIR_B1_OUT;
 	}
 	if (s->io_bits & 0xff0000) {
 		if (devno == 0)
-			config |= BUF_C0;
+			config |= PCM3724_DIO_DIR_C0_OUT;
 		else
-			config |= BUF_C1;
+			config |= PCM3724_DIO_DIR_C1_OUT;
 	}
 	return config;
 }
@@ -101,7 +113,7 @@ static void do_3724_config(struct comedi_device *dev,
 	else
 		port_8255_cfg = dev->iobase + I8255_SIZE + I8255_CTRL_REG;
 
-	outb(buffer_config, dev->iobase + 8);	/* update buffer register */
+	outb(buffer_config, dev->iobase + PCM3724_DIO_DIR_REG);
 
 	outb(config, port_8255_cfg);
 }
@@ -123,24 +135,24 @@ static void enable_chan(struct comedi_device *dev, struct comedi_subdevice *s,
 		priv->dio_2 |= mask;
 
 	if (priv->dio_1 & 0xff0000)
-		gatecfg |= GATE_C0;
+		gatecfg |= PCM3724_GATE_CTRL_C0_ENA;
 
 	if (priv->dio_1 & 0xff00)
-		gatecfg |= GATE_B0;
+		gatecfg |= PCM3724_GATE_CTRL_B0_ENA;
 
 	if (priv->dio_1 & 0xff)
-		gatecfg |= GATE_A0;
+		gatecfg |= PCM3724_GATE_CTRL_A0_ENA;
 
 	if (priv->dio_2 & 0xff0000)
-		gatecfg |= GATE_C1;
+		gatecfg |= PCM3724_GATE_CTRL_C1_ENA;
 
 	if (priv->dio_2 & 0xff00)
-		gatecfg |= GATE_B1;
+		gatecfg |= PCM3724_GATE_CTRL_B1_ENA;
 
 	if (priv->dio_2 & 0xff)
-		gatecfg |= GATE_A1;
+		gatecfg |= PCM3724_GATE_CTRL_A1_ENA;
 
-	outb(gatecfg, dev->iobase + 9);
+	outb(gatecfg, dev->iobase + PCM3724_GATE_CTRL_REG);
 }
 
 /* overriding the 8255 insn config */