diff --git a/drivers/staging/comedi/drivers/8255.c b/drivers/staging/comedi/drivers/8255.c
index 446dfc5c970..5e0e8ff8936 100644
--- a/drivers/staging/comedi/drivers/8255.c
+++ b/drivers/staging/comedi/drivers/8255.c
@@ -103,17 +103,14 @@ struct subdev_8255_private {
 	int have_irq;
 };
 
-#define CALLBACK_ARG	(((struct subdev_8255_private *)s->private)->cb_arg)
-#define CALLBACK_FUNC	(((struct subdev_8255_private *)s->private)->cb_func)
-#define subdevpriv	((struct subdev_8255_private *)s->private)
-
 void subdev_8255_interrupt(struct comedi_device *dev,
 			   struct comedi_subdevice *s)
 {
+	struct subdev_8255_private *spriv = s->private;
 	short d;
 
-	d = CALLBACK_FUNC(0, _8255_DATA, 0, CALLBACK_ARG);
-	d |= (CALLBACK_FUNC(0, _8255_DATA + 1, 0, CALLBACK_ARG) << 8);
+	d = spriv->cb_func(0, _8255_DATA, 0, spriv->cb_arg);
+	d |= (spriv->cb_func(0, _8255_DATA + 1, 0, spriv->cb_arg) << 8);
 
 	comedi_buf_put(s->async, d);
 	s->async->events |= COMEDI_CB_EOS;
@@ -138,30 +135,33 @@ static int subdev_8255_insn(struct comedi_device *dev,
 			    struct comedi_subdevice *s,
 			    struct comedi_insn *insn, unsigned int *data)
 {
+	struct subdev_8255_private *spriv = s->private;
+
 	if (data[0]) {
 		s->state &= ~data[0];
 		s->state |= (data[0] & data[1]);
 
 		if (data[0] & 0xff)
-			CALLBACK_FUNC(1, _8255_DATA, s->state & 0xff,
-				      CALLBACK_ARG);
+			spriv->cb_func(1, _8255_DATA, s->state & 0xff,
+				       spriv->cb_arg);
 		if (data[0] & 0xff00)
-			CALLBACK_FUNC(1, _8255_DATA + 1, (s->state >> 8) & 0xff,
-				      CALLBACK_ARG);
+			spriv->cb_func(1, _8255_DATA + 1,
+				       (s->state >> 8) & 0xff, spriv->cb_arg);
 		if (data[0] & 0xff0000)
-			CALLBACK_FUNC(1, _8255_DATA + 2,
-				      (s->state >> 16) & 0xff, CALLBACK_ARG);
+			spriv->cb_func(1, _8255_DATA + 2,
+				       (s->state >> 16) & 0xff, spriv->cb_arg);
 	}
 
-	data[1] = CALLBACK_FUNC(0, _8255_DATA, 0, CALLBACK_ARG);
-	data[1] |= (CALLBACK_FUNC(0, _8255_DATA + 1, 0, CALLBACK_ARG) << 8);
-	data[1] |= (CALLBACK_FUNC(0, _8255_DATA + 2, 0, CALLBACK_ARG) << 16);
+	data[1] = spriv->cb_func(0, _8255_DATA, 0, spriv->cb_arg);
+	data[1] |= (spriv->cb_func(0, _8255_DATA + 1, 0, spriv->cb_arg) << 8);
+	data[1] |= (spriv->cb_func(0, _8255_DATA + 2, 0, spriv->cb_arg) << 16);
 
 	return 2;
 }
 
 static void do_config(struct comedi_device *dev, struct comedi_subdevice *s)
 {
+	struct subdev_8255_private *spriv = s->private;
 	int config;
 
 	config = CR_CW;
@@ -174,7 +174,7 @@ static void do_config(struct comedi_device *dev, struct comedi_subdevice *s)
 		config |= CR_C_LO_IO;
 	if (!(s->io_bits & 0xf00000))
 		config |= CR_C_HI_IO;
-	CALLBACK_FUNC(1, _8255_CR, config, CALLBACK_ARG);
+	spriv->cb_func(1, _8255_CR, config, spriv->cb_arg);
 }
 
 static int subdev_8255_insn_config(struct comedi_device *dev,
@@ -310,21 +310,24 @@ int subdev_8255_init(struct comedi_device *dev, struct comedi_subdevice *s,
 		     int (*cb) (int, int, int, unsigned long),
 		     unsigned long arg)
 {
+	struct subdev_8255_private *spriv;
+
 	s->type = COMEDI_SUBD_DIO;
 	s->subdev_flags = SDF_READABLE | SDF_WRITABLE;
 	s->n_chan = 24;
 	s->range_table = &range_digital;
 	s->maxdata = 1;
 
-	s->private = kmalloc(sizeof(struct subdev_8255_private), GFP_KERNEL);
-	if (!s->private)
+	spriv = kmalloc(sizeof(*spriv), GFP_KERNEL);
+	if (!spriv)
 		return -ENOMEM;
+	s->private = spriv;
 
-	CALLBACK_ARG = arg;
+	spriv->cb_arg = arg;
 	if (cb == NULL)
-		CALLBACK_FUNC = subdev_8255_cb;
+		spriv->cb_func = subdev_8255_cb;
 	else
-		CALLBACK_FUNC = cb;
+		spriv->cb_func = cb;
 	s->insn_bits = subdev_8255_insn;
 	s->insn_config = subdev_8255_insn_config;
 
@@ -340,18 +343,20 @@ int subdev_8255_init_irq(struct comedi_device *dev, struct comedi_subdevice *s,
 			 int (*cb) (int, int, int, unsigned long),
 			 unsigned long arg)
 {
+	struct subdev_8255_private *spriv;
 	int ret;
 
 	ret = subdev_8255_init(dev, s, cb, arg);
 	if (ret < 0)
 		return ret;
+	spriv = s->private;
+
+	spriv->have_irq = 1;
 
 	s->do_cmdtest = subdev_8255_cmdtest;
 	s->do_cmd = subdev_8255_cmd;
 	s->cancel = subdev_8255_cancel;
 
-	subdevpriv->have_irq = 1;
-
 	return 0;
 }
 EXPORT_SYMBOL(subdev_8255_init_irq);
@@ -412,15 +417,15 @@ static int dev_8255_attach(struct comedi_device *dev,
 
 static void dev_8255_detach(struct comedi_device *dev)
 {
-	int i;
-	unsigned long iobase;
 	struct comedi_subdevice *s;
+	struct subdev_8255_private *spriv;
+	int i;
 
 	for (i = 0; i < dev->n_subdevices; i++) {
 		s = dev->subdevices + i;
 		if (s->type != COMEDI_SUBD_UNUSED) {
-			iobase = CALLBACK_ARG;
-			release_region(iobase, _8255_SIZE);
+			spriv = s->private;
+			release_region(spriv->cb_arg, _8255_SIZE);
 		}
 		subdev_8255_cleanup(dev, s);
 	}