staging: comedi: das800: cleanup das800_probe()

Make this function return a pointer to the boardinfo instead of an index.
 Since it's not typical, add a comment to clarify why this legacy driver
does a probe. For aesthetics, rename the local variable 'board' to 'index.

Consolidate the dev_dbg() messages when a probed boardinfo is used and
remove the extra dev_dbg() message when the boardinfo is not found.

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

diff --git a/drivers/staging/comedi/drivers/das800.c b/drivers/staging/comedi/drivers/das800.c
index 39d304a..bc9fa4b 100644 (file)
--- a/drivers/staging/comedi/drivers/das800.c
+++ b/drivers/staging/comedi/drivers/das800.c
@@ -604,44 +604,53 @@ static int das800_do_insn_bits(struct comedi_device *dev,
        return insn->n;
 }
 
-static int das800_probe(struct comedi_device *dev)
+static const struct das800_board *das800_probe(struct comedi_device *dev)
 {
        const struct das800_board *thisboard = dev->board_ptr;
-       int board = thisboard ? thisboard - das800_boards : -EINVAL;
+       int index = thisboard ? thisboard - das800_boards : -EINVAL;
        int id_bits;
        unsigned long irq_flags;
 
+       /*
+        * The dev->board_ptr will be set by comedi_device_attach() if the
+        * board name provided by the user matches a board->name in this
+        * driver. If so, this function sanity checks the id_bits to verify
+        * that the board is correct.
+        *
+        * If the dev->board_ptr is not set, the user is trying to attach
+        * an unspecified board to this driver. In this case the id_bits
+        * are used to 'probe' for the correct dev->board_ptr.
+        */
        spin_lock_irqsave(&dev->spinlock, irq_flags);
        id_bits = das800_ind_read(dev, ID) & 0x3;
        spin_unlock_irqrestore(&dev->spinlock, irq_flags);
 
        switch (id_bits) {
        case 0x0:
-               if (board == BOARD_DAS800 || board == BOARD_CIODAS800)
-                       break;
-               dev_dbg(dev->class_dev, "Board model (probed): DAS-800\n");
-               board = BOARD_DAS800;
+               if (index == BOARD_DAS800 || index == BOARD_CIODAS800)
+                       return thisboard;
+               index = BOARD_DAS800;
                break;
        case 0x2:
-               if (board == BOARD_DAS801 || board == BOARD_CIODAS801)
-                       break;
-               dev_dbg(dev->class_dev, "Board model (probed): DAS-801\n");
-               board = BOARD_DAS801;
+               if (index == BOARD_DAS801 || index == BOARD_CIODAS801)
+                       return thisboard;
+               index = BOARD_DAS801;
                break;
        case 0x3:
-               if (board == BOARD_DAS802 || board == BOARD_CIODAS802 ||
-                   board == BOARD_CIODAS80216)
-                       break;
-               dev_dbg(dev->class_dev, "Board model (probed): DAS-802\n");
-               board = BOARD_DAS802;
+               if (index == BOARD_DAS802 || index == BOARD_CIODAS802 ||
+                   index == BOARD_CIODAS80216)
+                       return thisboard;
+               index = BOARD_DAS802;
                break;
        default:
                dev_dbg(dev->class_dev, "Board model: 0x%x (unknown)\n",
                        id_bits);
-               board = -EINVAL;
-               break;
+               return NULL;
        }
-       return board;
+       dev_dbg(dev->class_dev, "Board model (probed): %s series\n",
+               das800_boards[index].name);
+
+       return &das800_boards[index];
 }
 
 static int das800_attach(struct comedi_device *dev, struct comedi_devconfig *it)
@@ -651,7 +660,6 @@ static int das800_attach(struct comedi_device *dev, struct comedi_devconfig *it)
        struct comedi_subdevice *s;
        unsigned int irq = it->options[1];
        unsigned long irq_flags;
-       int board;
        int ret;
 
        devpriv = comedi_alloc_devpriv(dev, sizeof(*devpriv));
@@ -662,13 +670,10 @@ static int das800_attach(struct comedi_device *dev, struct comedi_devconfig *it)
        if (ret)
                return ret;
 
-       board = das800_probe(dev);
-       if (board < 0) {
-               dev_dbg(dev->class_dev, "unable to determine board type\n");
+       thisboard = das800_probe(dev);
+       if (!thisboard)
                return -ENODEV;
-       }
-       dev->board_ptr = das800_boards + board;
-       thisboard = dev->board_ptr;
+       dev->board_ptr = thisboard;
        dev->board_name = thisboard->name;
 
        if (irq > 1 && irq <= 7) {