staging: comedi: cb_pcimdda: use comedi_subdevice 'readback'

Use the new comedi_subdevice 'readback' member and the core provided
(*insn_read) for the readback of the analog output subdevice channels.

Remove the unused private data and its allocation.

For aesthetics, rename the (*insn_write) and (*insn_read) functions.
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/cb_pcimdda.c

@@ -90,21 +90,14 @@ Configuration Options: not applicable, uses PCI auto config
 #define PCIMDDA_DA_CHAN(x)		(0x00 + (x) * 2)
 #define PCIMDDA_8255_BASE_REG		0x0c
 
-#define MAX_AO_READBACK_CHANNELS	6
-
-struct cb_pcimdda_private {
-	unsigned int ao_readback[MAX_AO_READBACK_CHANNELS];
-};
-
-static int cb_pcimdda_ao_winsn(struct comedi_device *dev,
+static int cb_pcimdda_ao_insn_write(struct comedi_device *dev,
 				    struct comedi_subdevice *s,
 				    struct comedi_insn *insn,
 				    unsigned int *data)
 {
-	struct cb_pcimdda_private *devpriv = dev->private;
 	unsigned int chan = CR_CHAN(insn->chanspec);
 	unsigned long offset = dev->iobase + PCIMDDA_DA_CHAN(chan);
-	unsigned int val = 0;
+	unsigned int val = s->readback[chan];
 	int i;
 
 	for (i = 0; i < insn->n; i++) {
@@ -122,45 +115,31 @@ static int cb_pcimdda_ao_winsn(struct comedi_device *dev,
 		outb(val & 0x00ff, offset);
 		outb((val >> 8) & 0x00ff, offset + 1);
 	}
-
-	/* Cache the last value for readback */
-	devpriv->ao_readback[chan] = val;
+	s->readback[chan] = val;
 
 	return insn->n;
 }
 
-static int cb_pcimdda_ao_rinsn(struct comedi_device *dev,
+static int cb_pcimdda_ao_insn_read(struct comedi_device *dev,
 				   struct comedi_subdevice *s,
 				   struct comedi_insn *insn,
 				   unsigned int *data)
 {
-	struct cb_pcimdda_private *devpriv = dev->private;
-	int chan = CR_CHAN(insn->chanspec);
-	unsigned long offset = dev->iobase + PCIMDDA_DA_CHAN(chan);
-	int i;
+	unsigned int chan = CR_CHAN(insn->chanspec);
 
-	for (i = 0; i < insn->n; i++) {
 	/* Initiate the simultaneous transfer */
-		inw(offset);
+	inw(dev->iobase + PCIMDDA_DA_CHAN(chan));
 
-		data[i] = devpriv->ao_readback[chan];
-	}
-
-	return insn->n;
+	return comedi_readback_insn_read(dev, s, insn, data);
 }
 
 static int cb_pcimdda_auto_attach(struct comedi_device *dev,
 					    unsigned long context_unused)
 {
 	struct pci_dev *pcidev = comedi_to_pci_dev(dev);
-	struct cb_pcimdda_private *devpriv;
 	struct comedi_subdevice *s;
 	int ret;
 
-	devpriv = comedi_alloc_devpriv(dev, sizeof(*devpriv));
-	if (!devpriv)
-		return -ENOMEM;
-
 	ret = comedi_pci_enable(dev);
 	if (ret)
 		return ret;
@@ -177,8 +156,12 @@ static int cb_pcimdda_auto_attach(struct comedi_device *dev,
 	s->n_chan	= 6;
 	s->maxdata	= 0xffff;
 	s->range_table	= &range_bipolar5;
-	s->insn_write	= cb_pcimdda_ao_winsn;
-	s->insn_read	= cb_pcimdda_ao_rinsn;
+	s->insn_write	= cb_pcimdda_ao_insn_write;
+	s->insn_read	= cb_pcimdda_ao_insn_read;
+
+	ret = comedi_alloc_subdev_readback(s);
+	if (ret)
+		return ret;
 
 	s = &dev->subdevices[1];
 	/* digital i/o subdevice */