staging: comedi: pass subdevice to comedi_buf_get()

Change the parameters of `comedi_buf_get()` to pass a pointer to the
comedi subdevice instead of a pointer to the "async" structure belonging
to the subdevice.

The function gets a sample value from the comedi buffer, but currently
only deals with 16-bit sample types.  A future version could deal with
16 or 32-bit sample types depending on the value of the SDF_LSAMPL
subdevice flag.

The main aim at the moment is to replace all the `struct comedi_async *`
parameters with `struct comedi_subdevice *` parameters in the comedi
driver API.

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>

drivers/staging/comedi/comedi_buf.c

@@ -431,8 +431,9 @@ int comedi_buf_put(struct comedi_subdevice *s, unsigned short x)
 }
 EXPORT_SYMBOL_GPL(comedi_buf_put);
 
-int comedi_buf_get(struct comedi_async *async, unsigned short *x)
+int comedi_buf_get(struct comedi_subdevice *s, unsigned short *x)
 {
+	struct comedi_async *async = s->async;
 	unsigned int n = comedi_buf_read_n_available(async);
 
 	if (n < sizeof(short))

drivers/staging/comedi/comedidev.h

@@ -344,7 +344,7 @@ unsigned int comedi_buf_read_alloc(struct comedi_async *, unsigned int);
 unsigned int comedi_buf_read_free(struct comedi_async *, unsigned int);
 
 int comedi_buf_put(struct comedi_subdevice *s, unsigned short x);
-int comedi_buf_get(struct comedi_async *, unsigned short *);
+int comedi_buf_get(struct comedi_subdevice *s, unsigned short *x);
 
 void comedi_buf_memcpy_to(struct comedi_async *async, unsigned int offset,
 			  const void *source, unsigned int num_bytes);

drivers/staging/comedi/drivers/amplc_pci230.c

@@ -1164,7 +1164,7 @@ static void pci230_handle_ao_nofifo(struct comedi_device *dev,
 		return;
 	for (i = 0; i < cmd->chanlist_len; i++) {
 		/* Read sample from Comedi's circular buffer. */
-		ret = comedi_buf_get(s->async, &data);
+		ret = comedi_buf_get(s, &data);
 		if (ret == 0) {
 			s->async->events |= COMEDI_CB_OVERFLOW;
 			pci230_ao_stop(dev, s);
@@ -1250,7 +1250,7 @@ static int pci230_handle_ao_fifo(struct comedi_device *dev,
 			for (i = 0; i < cmd->chanlist_len; i++) {
 				unsigned short datum;
 
-				comedi_buf_get(async, &datum);
+				comedi_buf_get(s, &datum);
 				pci230_ao_write_fifo(dev, datum,
 						     CR_CHAN(cmd->chanlist[i]));
 			}

drivers/staging/comedi/drivers/ni_mio_common.c

@@ -1149,7 +1149,7 @@ static void ni_ao_fifo_load(struct comedi_device *dev,
 
 	chan = async->cur_chan;
 	for (i = 0; i < n; i++) {
-		err &= comedi_buf_get(async, &d);
+		err &= comedi_buf_get(s, &d);
 		if (err == 0)
 			break;
 
@@ -1159,7 +1159,7 @@ static void ni_ao_fifo_load(struct comedi_device *dev,
 			packed_data = d & 0xffff;
 			/* 6711 only has 16 bit wide ao fifo */
 			if (board->reg_type != ni_reg_6711) {
-				err &= comedi_buf_get(async, &d);
+				err &= comedi_buf_get(s, &d);
 				if (err == 0)
 					break;
 				chan++;

drivers/staging/comedi/drivers/usbdux.c

@@ -484,7 +484,7 @@ static void usbduxsub_ao_isoc_irq(struct urb *urb)
 			unsigned int chan = devpriv->ao_chanlist[i];
 			unsigned short val;
 
-			ret = comedi_buf_get(s->async, &val);
+			ret = comedi_buf_get(s, &val);
 			if (ret < 0) {
 				dev_err(dev->class_dev, "buffer underflow\n");
 				s->async->events |= (COMEDI_CB_EOA |

drivers/staging/comedi/drivers/usbduxsigma.c

@@ -423,7 +423,7 @@ static void usbduxsigma_ao_urb_complete(struct urb *urb)
 			unsigned int chan = devpriv->ao_chanlist[i];
 			unsigned short val;
 
-			ret = comedi_buf_get(s->async, &val);
+			ret = comedi_buf_get(s, &val);
 			if (ret < 0) {
 				dev_err(dev->class_dev, "buffer underflow\n");
 				s->async->events |= (COMEDI_CB_EOA |