staging: comedi: pcl816: tidy up pcl818_check()
This function probes a number of the boards registers during the
(*attach) to verify that it is actually a PCL-816 compatible board.
For aesthetics, move the function closer to the (*attach).
To better match the pcl818 driver, allocate the private data before
calling pcl816_check().
Refactor the function to return an errno if fails. Change the errno
from -EIO to -ENODEV and remove the unnecessary dev_err() noise.
Make sure the CONTROL register is reset to a known state after the
check. The 0x18 value actually defines an invalid interrupt selection
and sets an undefined bit.
Add a couple comments to clarify the magic values.
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>
diff --git a/drivers/staging/comedi/drivers/pcl816.c b/drivers/staging/comedi/drivers/pcl816.c
index aae2947..2e383eb 100644
--- a/drivers/staging/comedi/drivers/pcl816.c
+++ b/drivers/staging/comedi/drivers/pcl816.c
@@ -614,25 +614,6 @@
return 0;
}
-static int pcl816_check(unsigned long iobase)
-{
- outb(0x00, iobase + PCL816_MUX);
- udelay(1);
- if (inb(iobase + PCL816_MUX) != 0x00)
- return 1; /* there isn't card */
- outb(0x55, iobase + PCL816_MUX);
- udelay(1);
- if (inb(iobase + PCL816_MUX) != 0x55)
- return 1; /* there isn't card */
- outb(0x00, iobase + PCL816_MUX);
- udelay(1);
- outb(0x18, iobase + PCL816_CONTROL);
- udelay(1);
- if (inb(iobase + PCL816_CONTROL) != 0x18)
- return 1; /* there isn't card */
- return 0; /* ok, card exist */
-}
-
static void pcl816_reset(struct comedi_device *dev)
{
unsigned long timer_base = dev->iobase + PCL816_TIMER_BASE;
@@ -733,6 +714,30 @@
dev->iobase + PCL816_MUX);
}
+static int pcl816_check(struct comedi_device *dev)
+{
+ /* the MUX register should return the same value written */
+ outb(0x00, dev->iobase + PCL816_MUX);
+ if (inb(dev->iobase + PCL816_MUX) != 0x00)
+ return -ENODEV;
+ outb(0x55, dev->iobase + PCL816_MUX);
+ if (inb(dev->iobase + PCL816_MUX) != 0x55)
+ return -ENODEV;
+
+ /* reset the MUX register to a known state */
+ outb(0x00, dev->iobase + PCL816_MUX);
+
+ /* the CONTROL register should return the same value written */
+ outb(0x18, dev->iobase + PCL816_CONTROL);
+ if (inb(dev->iobase + PCL816_CONTROL) != 0x18)
+ return -ENODEV;
+
+ /* reset the CONTROL register to a known state */
+ outb(0x00, dev->iobase + PCL816_CONTROL);
+
+ return 0;
+}
+
static int pcl816_attach(struct comedi_device *dev, struct comedi_devconfig *it)
{
const struct pcl816_board *board = comedi_board(dev);
@@ -741,18 +746,17 @@
int ret;
int i;
+ devpriv = comedi_alloc_devpriv(dev, sizeof(*devpriv));
+ if (!devpriv)
+ return -ENOMEM;
+
ret = comedi_request_region(dev, it->options[0], 0x10);
if (ret)
return ret;
- if (pcl816_check(dev->iobase)) {
- dev_err(dev->class_dev, "I can't detect board. FAIL!\n");
- return -EIO;
- }
-
- devpriv = comedi_alloc_devpriv(dev, sizeof(*devpriv));
- if (!devpriv)
- return -ENOMEM;
+ ret = pcl816_check(dev);
+ if (ret)
+ return ret;
/* we can use IRQ 2-7 for async command support */
if (it->options[1] >= 2 && it->options[1] <= 7) {
