staging: comedi: store the 'index' for each subdevice

Store the 'index' for each comedi_subdevice when they are initially
allocated by comedi_alloc_subdevice(). This allows removing the
pointer math in comedi_fops.c which is used to figure out the
index that user space uses to access the individual subdevices.

Fix the ni_mio_common driver so it also uses the 'index' instead
of doing the pointer math.

Also, remove a couple unused macros in the pcmda12, pcmmio, and
pcmuio drivers which also do the pointer math to figure out the
index.

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>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index dda47b161bcf..2fd577fa941e 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -169,7 +169,7 @@ static int resize_async_buffer(struct comedi_device *dev,
 	}
 
 	DPRINTK("comedi%i subd %d buffer resized to %i bytes\n",
-		dev->minor, (int)(s - dev->subdevices), async->prealloc_bufsz);
+		dev->minor, s->index, async->prealloc_bufsz);
 	return 0;
 }
 
@@ -624,13 +624,13 @@ static int do_devinfo_ioctl(struct comedi_device *dev,
 
 	s = comedi_read_subdevice(info);
 	if (s)
-		devinfo.read_subdevice = s - dev->subdevices;
+		devinfo.read_subdevice = s->index;
 	else
 		devinfo.read_subdevice = -1;
 
 	s = comedi_write_subdevice(info);
 	if (s)
-		devinfo.write_subdevice = s - dev->subdevices;
+		devinfo.write_subdevice = s->index;
 	else
 		devinfo.write_subdevice = -1;
 
@@ -2398,7 +2398,7 @@ int comedi_alloc_subdevice_minor(struct comedi_device *dev,
 	s->minor = i;
 	csdev = device_create(comedi_class, dev->class_dev,
 			      MKDEV(COMEDI_MAJOR, i), NULL, "comedi%i_subd%i",
-			      dev->minor, (int)(s - dev->subdevices));
+			      dev->minor, s->index);
 	if (!IS_ERR(csdev))
 		s->class_dev = csdev;
 	dev_set_drvdata(csdev, info);