staging: comedi: addi_apci_1032: check shared interrupt

In the interrupt service routine, check the device is asserting the
shared interrupt line and check that interrupts have been enabled.

When attaching the device, disable interrupts before setting up the
interrupt handler to avoid handling spurious interrupts before the
device is ready.
Signed-off-by: NIan Abbott <abbotti@mev.co.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/addi_apci_1032.c

@@ -31,6 +31,7 @@
 
 #include "../comedidev.h"
 #include "comedi_fc.h"
+#include "amcc_s5933.h"
 
 /*
  * I/O Register Map
@@ -45,6 +46,7 @@
 #define APCI1032_CTRL_INT_ENA		(1 << 2)
 
 struct apci1032_private {
+	unsigned long amcc_iobase;	/* base of AMCC I/O registers */
 	unsigned int mode1;	/* rising-edge/high level channels */
 	unsigned int mode2;	/* falling-edge/low level channels */
 	unsigned int ctrl;	/* interrupt mode OR (edge) . AND (level) */
@@ -218,11 +220,21 @@ static int apci1032_cos_cancel(struct comedi_device *dev,
 static irqreturn_t apci1032_interrupt(int irq, void *d)
 {
 	struct comedi_device *dev = d;
+	struct apci1032_private *devpriv = dev->private;
 	struct comedi_subdevice *s = dev->read_subdev;
 	unsigned int ctrl;
 
-	/* disable the interrupt */
+	/* check interrupt is from this device */
+	if ((inl(devpriv->amcc_iobase + AMCC_OP_REG_INTCSR) &
+	     INTCSR_INTR_ASSERTED) == 0)
+		return IRQ_NONE;
+
+	/* check interrupt is enabled */
 	ctrl = inl(dev->iobase + APCI1032_CTRL_REG);
+	if ((ctrl & APCI1032_CTRL_INT_ENA) == 0)
+		return IRQ_HANDLED;
+
+	/* disable the interrupt */
 	outl(ctrl & ~APCI1032_CTRL_INT_ENA, dev->iobase + APCI1032_CTRL_REG);
 
 	s->state = inl(dev->iobase + APCI1032_STATUS_REG) & 0xffff;
@@ -265,8 +277,9 @@ static int __devinit apci1032_auto_attach(struct comedi_device *dev,
 	if (ret)
 		return ret;
 
+	devpriv->amcc_iobase = pci_resource_start(pcidev, 0);
 	dev->iobase = pci_resource_start(pcidev, 1);
-
+	apci1032_reset(dev);
 	if (pcidev->irq > 0) {
 		ret = request_irq(pcidev->irq, apci1032_interrupt, IRQF_SHARED,
 				  dev->board_name, dev);
@@ -305,7 +318,6 @@ static int __devinit apci1032_auto_attach(struct comedi_device *dev,
 		s->type		= COMEDI_SUBD_UNUSED;
 	}
 
-	apci1032_reset(dev);
 	return 0;
 }