staging: comedi: ni_mio_common: add "no_channel" versions of some functions

ni_release_ai_mite_channel(), ni_release_ao_mite_channel(),
ni_release_gpct_mite_channel() and ni_release_cdo_mite_channel()
call functions which interpret -1 as a special value meaning "no channel".
This patch adds explicit "no_channel" versions instead.

On the other hand, after "no_channel" versions are used,
ni_set_ai_dma_channel(), ni_set_ao_dma_channel(),
ni_set_gpct_dma_channel(), ni_set_cdo_dma_channel() are called with actual
"channel" parameter being always unsigned, so their signatures are changed
accordingly.

A side benefit of the changes is suppressesing 4 sparse warnings:
"warning: shift too big (4294967295) for type int".
Signed-off-by: Andrzej Pietrasiewicz <andrzejtp2010@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/ni_mio_common.c

@@ -579,48 +579,54 @@ static inline unsigned ni_stc_dma_channel_select_bitfield(unsigned channel)
 	return 0;
 }
 
-/* negative channel means no channel */
-static inline void ni_set_ai_dma_channel(struct comedi_device *dev, int channel)
+static inline void ni_set_ai_dma_channel(struct comedi_device *dev,
+					 unsigned channel)
 {
-	unsigned bits = 0;
-
-	if (channel >= 0)
-		bits = ni_stc_dma_channel_select_bitfield(channel);
+	unsigned bits = ni_stc_dma_channel_select_bitfield(channel);
 
 	ni_set_bitfield(dev, NI_E_DMA_AI_AO_SEL_REG,
 			NI_E_DMA_AI_SEL_MASK, NI_E_DMA_AI_SEL(bits));
 }
 
-/* negative channel means no channel */
-static inline void ni_set_ao_dma_channel(struct comedi_device *dev, int channel)
+static inline void ni_set_ai_dma_no_channel(struct comedi_device *dev)
 {
-	unsigned bits = 0;
+	ni_set_bitfield(dev, NI_E_DMA_AI_AO_SEL_REG, NI_E_DMA_AI_SEL_MASK, 0);
+}
 
-	if (channel >= 0)
-		bits = ni_stc_dma_channel_select_bitfield(channel);
+static inline void ni_set_ao_dma_channel(struct comedi_device *dev,
+					 unsigned channel)
+{
+	unsigned bits = ni_stc_dma_channel_select_bitfield(channel);
 
 	ni_set_bitfield(dev, NI_E_DMA_AI_AO_SEL_REG,
 			NI_E_DMA_AO_SEL_MASK, NI_E_DMA_AO_SEL(bits));
 }
 
-/* negative channel means no channel */
+static inline void ni_set_ao_dma_no_channel(struct comedi_device *dev)
+{
+	ni_set_bitfield(dev, NI_E_DMA_AI_AO_SEL_REG, NI_E_DMA_AO_SEL_MASK, 0);
+}
+
 static inline void ni_set_gpct_dma_channel(struct comedi_device *dev,
 					   unsigned gpct_index,
-					   int channel)
+					   unsigned channel)
 {
-	unsigned bits = 0;
-
-	if (channel >= 0)
-		bits = ni_stc_dma_channel_select_bitfield(channel);
+	unsigned bits = ni_stc_dma_channel_select_bitfield(channel);
 
 	ni_set_bitfield(dev, NI_E_DMA_G0_G1_SEL_REG,
 			NI_E_DMA_G0_G1_SEL_MASK(gpct_index),
 			NI_E_DMA_G0_G1_SEL(gpct_index, bits));
 }
 
-/* negative mite_channel means no channel */
+static inline void ni_set_gpct_dma_no_channel(struct comedi_device *dev,
+					      unsigned gpct_index)
+{
+	ni_set_bitfield(dev, NI_E_DMA_G0_G1_SEL_REG,
+			NI_E_DMA_G0_G1_SEL_MASK(gpct_index), 0);
+}
+
 static inline void ni_set_cdo_dma_channel(struct comedi_device *dev,
-					  int mite_channel)
+					  unsigned mite_channel)
 {
 	struct ni_private *devpriv = dev->private;
 	unsigned long flags;
@@ -628,16 +634,26 @@ static inline void ni_set_cdo_dma_channel(struct comedi_device *dev,
 
 	spin_lock_irqsave(&devpriv->soft_reg_copy_lock, flags);
 	devpriv->cdio_dma_select_reg &= ~NI_M_CDIO_DMA_SEL_CDO_MASK;
-	if (mite_channel >= 0) {
-		/*
-		 * XXX just guessing ni_stc_dma_channel_select_bitfield()
-		 * returns the right bits, under the assumption the cdio dma
-		 * selection works just like ai/ao/gpct.
-		 * Definitely works for dma channels 0 and 1.
-		 */
-		bits = ni_stc_dma_channel_select_bitfield(mite_channel);
-		devpriv->cdio_dma_select_reg |= NI_M_CDIO_DMA_SEL_CDO(bits);
-	}
+	/*
+	 * XXX just guessing ni_stc_dma_channel_select_bitfield()
+	 * returns the right bits, under the assumption the cdio dma
+	 * selection works just like ai/ao/gpct.
+	 * Definitely works for dma channels 0 and 1.
+	 */
+	bits = ni_stc_dma_channel_select_bitfield(mite_channel);
+	devpriv->cdio_dma_select_reg |= NI_M_CDIO_DMA_SEL_CDO(bits);
+	ni_writeb(dev, devpriv->cdio_dma_select_reg, NI_M_CDIO_DMA_SEL_REG);
+	mmiowb();
+	spin_unlock_irqrestore(&devpriv->soft_reg_copy_lock, flags);
+}
+
+static inline void ni_set_cdo_dma_no_channel(struct comedi_device *dev)
+{
+	struct ni_private *devpriv = dev->private;
+	unsigned long flags;
+
+	spin_lock_irqsave(&devpriv->soft_reg_copy_lock, flags);
+	devpriv->cdio_dma_select_reg &= ~NI_M_CDIO_DMA_SEL_CDO_MASK;
 	ni_writeb(dev, devpriv->cdio_dma_select_reg, NI_M_CDIO_DMA_SEL_REG);
 	mmiowb();
 	spin_unlock_irqrestore(&devpriv->soft_reg_copy_lock, flags);
@@ -745,7 +761,7 @@ static void ni_release_ai_mite_channel(struct comedi_device *dev)
 
 	spin_lock_irqsave(&devpriv->mite_channel_lock, flags);
 	if (devpriv->ai_mite_chan) {
-		ni_set_ai_dma_channel(dev, -1);
+		ni_set_ai_dma_no_channel(dev);
 		mite_release_channel(devpriv->ai_mite_chan);
 		devpriv->ai_mite_chan = NULL;
 	}
@@ -761,7 +777,7 @@ static void ni_release_ao_mite_channel(struct comedi_device *dev)
 
 	spin_lock_irqsave(&devpriv->mite_channel_lock, flags);
 	if (devpriv->ao_mite_chan) {
-		ni_set_ao_dma_channel(dev, -1);
+		ni_set_ao_dma_no_channel(dev);
 		mite_release_channel(devpriv->ao_mite_chan);
 		devpriv->ao_mite_chan = NULL;
 	}
@@ -781,7 +797,7 @@ static void ni_release_gpct_mite_channel(struct comedi_device *dev,
 		struct mite_channel *mite_chan =
 		    devpriv->counter_dev->counters[gpct_index].mite_chan;
 
-		ni_set_gpct_dma_channel(dev, gpct_index, -1);
+		ni_set_gpct_dma_no_channel(dev, gpct_index);
 		ni_tio_set_mite_channel(&devpriv->
 					counter_dev->counters[gpct_index],
 					NULL);
@@ -799,7 +815,7 @@ static void ni_release_cdo_mite_channel(struct comedi_device *dev)
 
 	spin_lock_irqsave(&devpriv->mite_channel_lock, flags);
 	if (devpriv->cdo_mite_chan) {
-		ni_set_cdo_dma_channel(dev, -1);
+		ni_set_cdo_dma_no_channel(dev);
 		mite_release_channel(devpriv->cdo_mite_chan);
 		devpriv->cdo_mite_chan = NULL;
 	}