staging: comedi: ni_pcidio: Add comedi_poll support

This patch is ported over by me (Ian Abbott) from the out-of-tree Comedi
git repository at "git://comedi.org/git/comedi/comedi.git".

The original patch is by Nicholas Nell.

The patch adds support for the COMEDI_POLL ioctl to the ni_pcidio
driver.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: Nicholas Nell <nicholas.nell@colorado.edu>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/drivers/ni_pcidio.c b/drivers/staging/comedi/drivers/ni_pcidio.c
index 5145bf1..88728bd 100644 (file)
--- a/drivers/staging/comedi/drivers/ni_pcidio.c
+++ b/drivers/staging/comedi/drivers/ni_pcidio.c
@@ -483,6 +483,21 @@ void ni_pcidio_event(struct comedi_device *dev, struct comedi_subdevice *s)
        comedi_event(dev, s);
 }
 
+static int ni_pcidio_poll(struct comedi_device *dev, struct comedi_subdevice *s)
+{
+       unsigned long irq_flags;
+       int count;
+
+       spin_lock_irqsave(&dev->spinlock, irq_flags);
+       spin_lock(&devpriv->mite_channel_lock);
+       if (devpriv->di_mite_chan)
+               mite_sync_input_dma(devpriv->di_mite_chan, s->async);
+       spin_unlock(&devpriv->mite_channel_lock);
+       count = s->async->buf_write_count - s->async->buf_read_count;
+       spin_unlock_irqrestore(&dev->spinlock, irq_flags);
+       return count;
+}
+
 static irqreturn_t nidio_interrupt(int irq, void *d)
 {
        struct comedi_device *dev = d;
@@ -498,7 +513,6 @@ static irqreturn_t nidio_interrupt(int irq, void *d)
        int status;
        int work = 0;
        unsigned int m_status = 0;
-       unsigned long irq_flags;
 
        /* interrupcions parasites */
        if (dev->attached == 0) {
@@ -506,6 +520,9 @@ static irqreturn_t nidio_interrupt(int irq, void *d)
                return IRQ_NONE;
        }
 
+       /* Lock to avoid race with comedi_poll */
+       spin_lock(&dev->spinlock);
+
        status = readb(devpriv->mite->daq_io_addr +
                       Interrupt_And_Window_Status);
        flags = readb(devpriv->mite->daq_io_addr + Group_1_Flags);
@@ -519,7 +536,7 @@ static irqreturn_t nidio_interrupt(int irq, void *d)
        /* printk("buf[4096]=%08x\n",
               *(unsigned int *)(async->prealloc_buf+4096)); */
 
-       spin_lock_irqsave(&devpriv->mite_channel_lock, irq_flags);
+       spin_lock(&devpriv->mite_channel_lock);
        if (devpriv->di_mite_chan)
                m_status = mite_get_status(devpriv->di_mite_chan);
 #ifdef MITE_DEBUG
@@ -544,7 +561,7 @@ static irqreturn_t nidio_interrupt(int irq, void *d)
                        disable_irq(dev->irq);
                }
        }
-       spin_unlock_irqrestore(&devpriv->mite_channel_lock, irq_flags);
+       spin_unlock(&devpriv->mite_channel_lock);
 
        while (status & DataLeft) {
                work++;
@@ -646,6 +663,8 @@ out:
                       Master_DMA_And_Interrupt_Control);
        }
 #endif
+
+       spin_unlock(&dev->spinlock);
        return IRQ_HANDLED;
 }
 
@@ -1252,6 +1271,7 @@ static int nidio_attach(struct comedi_device *dev, struct comedi_devconfig *it)
                s->len_chanlist = 32;   /* XXX */
                s->buf_change = &ni_pcidio_change;
                s->async_dma_dir = DMA_BIDIRECTIONAL;
+               s->poll = &ni_pcidio_poll;
 
                writel(0, devpriv->mite->daq_io_addr + Port_IO(0));
                writel(0, devpriv->mite->daq_io_addr + Port_Pin_Directions(0));