staging: comedi: add 'ioenabled' flag to device

Add 1-bit bit-field member `ioenabled` of type `bool` to `struct
comedi_device`.  Use this to keep track of whether a PCI device and its
BARs have been successfully enabled by `comedi_pci_enable()`.  This
avoids overloading the meaning of the `iobase` member which is used by
several drivers to hold the base port I/O address of a board's "main"
registers.  Other drivers using MMIO use `iobase` as a flag to indicate
that the preceding call to `comedi_pci_enable()` was successful.  They
no longer need to do that.

The name `ioenabled` is intended to be PCI-agnostic so it can be used
for similar purposes by non-PCI drivers.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/comedi_pci.c

@@ -55,6 +55,8 @@ int comedi_pci_enable(struct comedi_device *dev)
 						: dev->driver->driver_name);
 	if (rc < 0)
 		pci_disable_device(pcidev);
+	else
+		dev->ioenabled = true;
 
 	return rc;
 }
@@ -68,10 +70,11 @@ void comedi_pci_disable(struct comedi_device *dev)
 {
 	struct pci_dev *pcidev = comedi_to_pci_dev(dev);
 
-	if (pcidev && dev->iobase) {
+	if (pcidev && dev->ioenabled) {
 		pci_release_regions(pcidev);
 		pci_disable_device(pcidev);
 	}
+	dev->ioenabled = false;
 }
 EXPORT_SYMBOL_GPL(comedi_pci_disable);
 

drivers/staging/comedi/comedidev.h

@@ -209,6 +209,7 @@ struct comedi_device {
 	const void *board_ptr;
 	bool attached:1;
 	bool in_request_module:1;
+	bool ioenabled:1;
 	spinlock_t spinlock;
 	struct mutex mutex;
 

drivers/staging/comedi/drivers.c

@@ -110,6 +110,7 @@ static void cleanup_device(struct comedi_device *dev)
 	dev->board_name = NULL;
 	dev->board_ptr = NULL;
 	dev->iobase = 0;
+	dev->ioenabled = false;
 	dev->irq = 0;
 	dev->read_subdev = NULL;
 	dev->write_subdev = NULL;