staging: comedi: amplc_pci230: simplify interrupt enable handling

`struct pci230_private` has two members to manage the enabled interrupt
sources.  `int_en` is the interrupt sources we want to be enabled and
`ier` is a shadow of the write-only interrupt enable register.  They
have the same value most of the time.  They differ in the interrupt
handler (`pci230_interrupt()`) itself when it temporarily clears bits in
the interrupt enable register and the `ier` member in order to unlatch
them in hardware, but leaves the `int_en` member alone.  They also
differ in `pci230_ai_stop()` and `pci230_ao_stop()` which clear bits in
the `int_en` member and wait for the interrupt handler to finish before
copying the value to the `ier` member and the interrupt enable register.

Simplify the handling a bit, by making the `ier` member take on the role
of the `int_en` member, and allowing the value to differ from the
interrupt enable register while the interrupt handler is running.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/drivers/amplc_pci230.c b/drivers/staging/comedi/drivers/amplc_pci230.c
index 7748e17..66e7a47 100644 (file)
--- a/drivers/staging/comedi/drivers/amplc_pci230.c
+++ b/drivers/staging/comedi/drivers/amplc_pci230.c
@@ -499,8 +499,7 @@ struct pci230_private {
        unsigned short daccon;          /* DACCON register value */
        unsigned short adcfifothresh;   /* ADC FIFO threshold (PCI230+/260+) */
        unsigned short adcg;            /* ADCG register value */
-       unsigned char int_en;           /* Interrupt enable bits */
-       unsigned char ier;              /* Copy of interrupt enable register */
+       unsigned char ier;              /* Interrupt enable bits */
        unsigned char res_owned[NUM_OWNERS]; /* Owned resources */
        bool intr_running:1;            /* Flag set in interrupt routine */
        bool ai_bipolar:1;              /* Flag AI range is bipolar */
@@ -1049,15 +1048,12 @@ static void pci230_ao_stop(struct comedi_device *dev,
         * unless we are called from the interrupt routine.
         */
        spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
-       devpriv->int_en &= ~intsrc;
+       devpriv->ier &= ~intsrc;
        while (devpriv->intr_running && devpriv->intr_cpuid != THISCPU) {
                spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);
                spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
        }
-       if (devpriv->ier != devpriv->int_en) {
-               devpriv->ier = devpriv->int_en;
-               outb(devpriv->ier, dev->iobase + PCI230_INT_SCE);
-       }
+       outb(devpriv->ier, dev->iobase + PCI230_INT_SCE);
        spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);
        if (devpriv->hwver >= 2) {
                /*
@@ -1311,7 +1307,6 @@ static void pci230_ao_start(struct comedi_device *dev,
                        /* Not using DAC FIFO. */
                        /* Enable CT1 timer interrupt. */
                        spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
-                       devpriv->int_en |= PCI230_INT_ZCLK_CT1;
                        devpriv->ier |= PCI230_INT_ZCLK_CT1;
                        outb(devpriv->ier, dev->iobase + PCI230_INT_SCE);
                        spin_unlock_irqrestore(&devpriv->isr_spinlock,
@@ -1327,7 +1322,6 @@ static void pci230_ao_start(struct comedi_device *dev,
        if (devpriv->hwver >= 2) {
                /* Using DAC FIFO.  Enable DAC FIFO interrupt. */
                spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
-               devpriv->int_en |= PCI230P2_INT_DAC;
                devpriv->ier |= PCI230P2_INT_DAC;
                outb(devpriv->ier, dev->iobase + PCI230_INT_SCE);
                spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);
@@ -1892,15 +1886,12 @@ static void pci230_ai_stop(struct comedi_device *dev,
         * Disable ADC interrupt and wait for interrupt routine to finish
         * running unless we are called from the interrupt routine.
         */
-       devpriv->int_en &= ~PCI230_INT_ADC;
+       devpriv->ier &= ~PCI230_INT_ADC;
        while (devpriv->intr_running && devpriv->intr_cpuid != THISCPU) {
                spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);
                spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
        }
-       if (devpriv->ier != devpriv->int_en) {
-               devpriv->ier = devpriv->int_en;
-               outb(devpriv->ier, dev->iobase + PCI230_INT_SCE);
-       }
+       outb(devpriv->ier, dev->iobase + PCI230_INT_SCE);
        spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);
        /*
         * Reset FIFO, disable FIFO and set start conversion source to none.
@@ -1935,7 +1926,6 @@ static void pci230_ai_start(struct comedi_device *dev,
 
        /* Enable ADC FIFO trigger level interrupt. */
        spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
-       devpriv->int_en |= PCI230_INT_ADC;
        devpriv->ier |= PCI230_INT_ADC;
        outb(devpriv->ier, dev->iobase + PCI230_INT_SCE);
        spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);
@@ -2379,7 +2369,7 @@ static int pci230_ai_cancel(struct comedi_device *dev,
 /* Interrupt handler */
 static irqreturn_t pci230_interrupt(int irq, void *d)
 {
-       unsigned char status_int, valid_status_int;
+       unsigned char status_int, valid_status_int, temp_ier;
        struct comedi_device *dev = (struct comedi_device *)d;
        struct pci230_private *devpriv = dev->private;
        struct comedi_subdevice *s;
@@ -2392,14 +2382,14 @@ static irqreturn_t pci230_interrupt(int irq, void *d)
                return IRQ_NONE;
 
        spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
-       valid_status_int = devpriv->int_en & status_int;
+       valid_status_int = devpriv->ier & status_int;
        /*
         * Disable triggered interrupts.
         * (Only those interrupts that need re-enabling, are, later in the
         * handler).
         */
-       devpriv->ier = devpriv->int_en & ~status_int;
-       outb(devpriv->ier, dev->iobase + PCI230_INT_SCE);
+       temp_ier = devpriv->ier & ~status_int;
+       outb(temp_ier, dev->iobase + PCI230_INT_SCE);
        devpriv->intr_running = true;
        devpriv->intr_cpuid = THISCPU;
        spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);
@@ -2432,10 +2422,8 @@ static irqreturn_t pci230_interrupt(int irq, void *d)
 
        /* Reenable interrupts. */
        spin_lock_irqsave(&devpriv->isr_spinlock, irqflags);
-       if (devpriv->ier != devpriv->int_en) {
-               devpriv->ier = devpriv->int_en;
+       if (devpriv->ier != temp_ier)
                outb(devpriv->ier, dev->iobase + PCI230_INT_SCE);
-       }
        devpriv->intr_running = false;
        spin_unlock_irqrestore(&devpriv->isr_spinlock, irqflags);