staging: comedi: ni_labpc: migrate DMA transfer set-up

Migrate the code for setting up an ISA DMA transfer into a new function
`labpc_setup_dma()` in the "ni_labpc_isadma" module.  Provide a dummy
inline function in "ni_labpc_isadma.h" if the "ni_labpc_isadma" module
is not being built.

The static function `labpc_suggest_transfer_size()` also needs to move
across to the new module.

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

drivers/staging/comedi/drivers/ni_labpc.c

@@ -387,32 +387,6 @@ static int labpc_ai_insn_read(struct comedi_device *dev,
 	return insn->n;
 }
 
-#ifdef CONFIG_ISA_DMA_API
-/* utility function that suggests a dma transfer size in bytes */
-static unsigned int labpc_suggest_transfer_size(const struct comedi_cmd *cmd)
-{
-	unsigned int size;
-	unsigned int freq;
-
-	if (cmd->convert_src == TRIG_TIMER)
-		freq = 1000000000 / cmd->convert_arg;
-	/* return some default value */
-	else
-		freq = 0xffffffff;
-
-	/* make buffer fill in no more than 1/3 second */
-	size = (freq / 3) * sample_size;
-
-	/* set a minimum and maximum size allowed */
-	if (size > dma_buffer_size)
-		size = dma_buffer_size - dma_buffer_size % sample_size;
-	else if (size < sample_size)
-		size = sample_size;
-
-	return size;
-}
-#endif
-
 static bool labpc_use_continuous_mode(const struct comedi_cmd *cmd,
 				      enum scan_mode mode)
 {
@@ -883,31 +857,8 @@ static int labpc_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 
 	labpc_clear_adc_fifo(dev);
 
-#ifdef CONFIG_ISA_DMA_API
-	/*  set up dma transfer */
-	if (xfer == isa_dma_transfer) {
-		unsigned long irq_flags;
-
-		irq_flags = claim_dma_lock();
-		disable_dma(devpriv->dma_chan);
-		/* clear flip-flop to make sure 2-byte registers for
-		 * count and address get set correctly */
-		clear_dma_ff(devpriv->dma_chan);
-		set_dma_addr(devpriv->dma_chan, devpriv->dma_addr);
-		/*  set appropriate size of transfer */
-		devpriv->dma_transfer_size = labpc_suggest_transfer_size(cmd);
-		if (cmd->stop_src == TRIG_COUNT &&
-		    devpriv->count * sample_size < devpriv->dma_transfer_size) {
-			devpriv->dma_transfer_size =
-			    devpriv->count * sample_size;
-		}
-		set_dma_count(devpriv->dma_chan, devpriv->dma_transfer_size);
-		enable_dma(devpriv->dma_chan);
-		release_dma_lock(irq_flags);
-		/*  enable board's dma */
-		devpriv->cmd3 |= (CMD3_DMAEN | CMD3_DMATCINTEN);
-	}
-#endif
+	if (xfer == isa_dma_transfer)
+		labpc_setup_dma(dev, s);
 
 	/*  enable error interrupts */
 	devpriv->cmd3 |= CMD3_ERRINTEN;

drivers/staging/comedi/drivers/ni_labpc_isadma.c

@@ -29,6 +29,57 @@
 
 /* size in bytes of dma buffer */
 static const int dma_buffer_size = 0xff00;
+/* 2 bytes per sample */
+static const int sample_size = 2;
+
+/* utility function that suggests a dma transfer size in bytes */
+static unsigned int labpc_suggest_transfer_size(const struct comedi_cmd *cmd)
+{
+	unsigned int size;
+	unsigned int freq;
+
+	if (cmd->convert_src == TRIG_TIMER)
+		freq = 1000000000 / cmd->convert_arg;
+	else
+		/* return some default value */
+		freq = 0xffffffff;
+
+	/* make buffer fill in no more than 1/3 second */
+	size = (freq / 3) * sample_size;
+
+	/* set a minimum and maximum size allowed */
+	if (size > dma_buffer_size)
+		size = dma_buffer_size - dma_buffer_size % sample_size;
+	else if (size < sample_size)
+		size = sample_size;
+
+	return size;
+}
+
+void labpc_setup_dma(struct comedi_device *dev, struct comedi_subdevice *s)
+{
+	struct labpc_private *devpriv = dev->private;
+	struct comedi_cmd *cmd = &s->async->cmd;
+	unsigned long irq_flags;
+
+	irq_flags = claim_dma_lock();
+	disable_dma(devpriv->dma_chan);
+	/* clear flip-flop to make sure 2-byte registers for
+	 * count and address get set correctly */
+	clear_dma_ff(devpriv->dma_chan);
+	set_dma_addr(devpriv->dma_chan, devpriv->dma_addr);
+	/* set appropriate size of transfer */
+	devpriv->dma_transfer_size = labpc_suggest_transfer_size(cmd);
+	if (cmd->stop_src == TRIG_COUNT &&
+	    devpriv->count * sample_size < devpriv->dma_transfer_size)
+		devpriv->dma_transfer_size = devpriv->count * sample_size;
+	set_dma_count(devpriv->dma_chan, devpriv->dma_transfer_size);
+	enable_dma(devpriv->dma_chan);
+	release_dma_lock(irq_flags);
+	/* set CMD3 bits for caller to enable DMA and interrupt */
+	devpriv->cmd3 |= (CMD3_DMAEN | CMD3_DMATCINTEN);
+}
+EXPORT_SYMBOL_GPL(labpc_setup_dma);
 
 int labpc_init_dma_chan(struct comedi_device *dev, unsigned int dma_chan)
 {

drivers/staging/comedi/drivers/ni_labpc_isadma.h

@@ -18,6 +18,7 @@ static inline bool labpc_have_dma_chan(struct comedi_device *dev)
 
 int labpc_init_dma_chan(struct comedi_device *dev, unsigned int dma_chan);
 void labpc_free_dma_chan(struct comedi_device *dev);
+void labpc_setup_dma(struct comedi_device *dev, struct comedi_subdevice *s);
 
 #else
 
@@ -36,6 +37,11 @@ static inline void labpc_free_dma_chan(struct comedi_device *dev)
 {
 }
 
+static inline void labpc_setup_dma(struct comedi_device *dev,
+				   struct comedi_subdevice *s)
+{
+}
+
 #endif
 
 #endif /* _NI_LABPC_ISADMA_H */