The "comedi_parport" driver treats a standard printer parallel port as a
COMEDI digital I/O device, driving the port's I/O registers directly.
It uses an admin-supplied configuration option (`it->options[0]`) to
configure the I/O port base address of the device.  Currently, the
driver allows any I/O base address to be specified as long as the I/O
region can be reserved, and it converts the specified `int` option value
holding the base address to `unsigned long`.

It doesn't make sense to allow base addresses that are not aligned to
4-byte boundaries (for SPP printer ports, although printer ports with
EPP/ECP support actually need to be aligned on 8-byte boundaries), so
add a check for 4-byte alignment.

Convert the option value that specifies the base address from `int` to
`unsigned int` instead of `unsigned long` so it ends up the same on
32-bit and 64-bit systems.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
---
 drivers/comedi/drivers/comedi_parport.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/comedi/drivers/comedi_parport.c b/drivers/comedi/drivers/comedi_parport.c
index 098738a688fe..2604680d86c4 100644
--- a/drivers/comedi/drivers/comedi_parport.c
+++ b/drivers/comedi/drivers/comedi_parport.c
@@ -225,9 +225,11 @@ static int parport_attach(struct comedi_device *dev,
 			  struct comedi_devconfig *it)
 {
 	struct comedi_subdevice *s;
+	unsigned int iobase = it->options[0];
 	int ret;
 
-	ret = comedi_request_region(dev, it->options[0], 0x03);
+	ret = comedi_check_request_region(dev, iobase, 0x03,
+					  0, UINT_MAX, 4);
 	if (ret)
 		return ret;
 
-- 
2.51.0