staging: comedi: das16: introduce das16_ai_range()

Clarify the (*attach) a bit by introducing a helper function to handle the
setup of the analog input 'range_table'.

Some of the boards supported by this driver do not have programmable ranges.
The analog input subdevice can use optional range information provided by
the user during the attach of the driver. Currently this range data is
allocated and stored in the private data.

Use the subdevice private data member instead and allocate the memory with
comedi_alloc_spriv(). The comedi core will automatically free this memory
when the driver is detached. If the allocation fails set the 'range_table'
to 'range_unknown' instead of failing the driver attach.

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/das16.c b/drivers/staging/comedi/drivers/das16.c
index 2564af0..cb38e4b 100644 (file)
--- a/drivers/staging/comedi/drivers/das16.c
+++ b/drivers/staging/comedi/drivers/das16.c
@@ -443,7 +443,6 @@ struct das16_private_struct {
        unsigned long           adc_byte_count;
        unsigned int            divisor1;
        unsigned int            divisor2;
-       struct comedi_lrange    *user_ai_range_table;
        struct comedi_lrange    *user_ao_range_table;
        struct timer_list       timer;
        short                   timer_running;
@@ -952,6 +951,42 @@ static void das16_free_dma(struct comedi_device *dev)
        }
 }
 
+static const struct comedi_lrange *das16_ai_range(struct comedi_device *dev,
+                                                 struct comedi_subdevice *s,
+                                                 struct comedi_devconfig *it,
+                                                 unsigned int pg_type,
+                                                 unsigned int status)
+{
+       unsigned int min = it->options[4];
+       unsigned int max = it->options[5];
+
+       /* get any user-defined input range */
+       if (pg_type == das16_pg_none && (min || max)) {
+               struct comedi_lrange *lrange;
+               struct comedi_krange *krange;
+
+               /* allocate single-range range table */
+               lrange = comedi_alloc_spriv(s,
+                                           sizeof(*lrange) + sizeof(*krange));
+               if (!lrange)
+                       return &range_unknown;
+
+               /* initialize ai range */
+               lrange->length = 1;
+               krange = lrange->range;
+               krange->min = min;
+               krange->max = max;
+               krange->flags = UNIT_volt;
+
+               return lrange;
+       }
+
+       /* use software programmable range */
+       if (status & DAS16_STATUS_UNIPOLAR)
+               return das16_ai_uni_lranges[pg_type];
+       return das16_ai_bip_lranges[pg_type];
+}
+
 static int das16_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 {
        const struct das16_board *board = dev->board_ptr;
@@ -1015,23 +1050,6 @@ static int das16_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 
        das16_alloc_dma(dev, it->options[2]);
 
-       /* get any user-defined input range */
-       if (board->ai_pg == das16_pg_none &&
-           (it->options[4] || it->options[5])) {
-               /* allocate single-range range table */
-               lrange = kzalloc(sizeof(*lrange) + sizeof(*krange), GFP_KERNEL);
-               if (!lrange)
-                       return -ENOMEM;
-
-               /* initialize ai range */
-               devpriv->user_ai_range_table = lrange;
-               lrange->length = 1;
-               krange = devpriv->user_ai_range_table->range;
-               krange->min = it->options[4];
-               krange->max = it->options[5];
-               krange->flags = UNIT_volt;
-       }
-
        /* get any user-defined output range */
        if (it->options[6] || it->options[7]) {
                /* allocate single-range range table */
@@ -1067,13 +1085,7 @@ static int das16_attach(struct comedi_device *dev, struct comedi_devconfig *it)
        }
        s->len_chanlist = s->n_chan;
        s->maxdata      = board->ai_maxdata;
-       if (devpriv->user_ai_range_table) { /*  user defined ai range */
-               s->range_table  = devpriv->user_ai_range_table;
-       } else if (status & DAS16_STATUS_UNIPOLAR) {
-               s->range_table  = das16_ai_uni_lranges[board->ai_pg];
-       } else {
-               s->range_table  = das16_ai_bip_lranges[board->ai_pg];
-       }
+       s->range_table  = das16_ai_range(dev, s, it, board->ai_pg, status);
        s->insn_read    = das16_ai_insn_read;
        if (devpriv->dma) {
                dev->read_subdev = s;
@@ -1153,7 +1165,6 @@ static void das16_detach(struct comedi_device *dev)
                if (dev->iobase)
                        das16_reset(dev);
                das16_free_dma(dev);
-               kfree(devpriv->user_ai_range_table);
                kfree(devpriv->user_ao_range_table);
 
                if (devpriv->extra_iobase)