staging: comedi: comedi_bond: handle base channel for insn_bits

If a DIO subdevice has more than 32 channels, its 'insn_bits' handler is
supposed to take account of the base channel from
`CR_CHAN(insn->chanspec)`.  (The comedi core will adjust the base
channel to 0 and shift the mask and data to compensate if the subdevice
has less than or equal to 32 channels.)  The "comedi_bond" driver
currently ignores the base channel and assumes it is 0.

Replace `comedi_dio_bitfield()` in the "kcomedilib" module with
`comedi_dio_bitfield2()` that takes account of the base channel, and
rewrite the "comedi_bond" driver's 'insn_bits' handler
(`bonding_dio_insn_bits()`) to take account of the base channel and use
the new function.

No other modules use `comedi_dio_bitfield()` so it is safe to replace it
with `comedi_dio_bitfield2()`.  The name follows that of the equivalent
function in the user-space comedilib.  If the base channel is non-zero
and the subdevice has less than or equal to 32 channels it needs to
adjust things in the same way as the comedi core (same as `parse_insn()`
in "comedi_fops.c") due to most drivers ignoring the base channel.

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

diff --git a/drivers/staging/comedi/comedilib.h b/drivers/staging/comedi/comedilib.h
index 47b1640241825b52702f96974bd87cab96cf8b94..56baf852ecf5ddc1dc26773739ef8b92b379d8af 100644 (file)
--- a/drivers/staging/comedi/comedilib.h
+++ b/drivers/staging/comedi/comedilib.h
@@ -25,8 +25,9 @@ int comedi_dio_get_config(struct comedi_device *dev, unsigned int subdev,
                          unsigned int chan, unsigned int *io);
 int comedi_dio_config(struct comedi_device *dev, unsigned int subdev,
                      unsigned int chan, unsigned int io);
-int comedi_dio_bitfield(struct comedi_device *dev, unsigned int subdev,
-                       unsigned int mask, unsigned int *bits);
+int comedi_dio_bitfield2(struct comedi_device *dev, unsigned int subdev,
+                        unsigned int mask, unsigned int *bits,
+                        unsigned int base_channel);
 int comedi_find_subdevice_by_type(struct comedi_device *dev, int type,
                                  unsigned int subd);
 int comedi_get_n_channels(struct comedi_device *dev, unsigned int subdevice);

diff --git a/drivers/staging/comedi/drivers/comedi_bond.c b/drivers/staging/comedi/drivers/comedi_bond.c
index a1c51a2e9c5974c8807df0d888c6ae97c7cc3f42..8e2696c8572078cc591bf06e34936c22139ee421 100644 (file)
--- a/drivers/staging/comedi/drivers/comedi_bond.c
+++ b/drivers/staging/comedi/drivers/comedi_bond.c
@@ -73,48 +73,59 @@ static int bonding_dio_insn_bits(struct comedi_device *dev,
                                 struct comedi_insn *insn, unsigned int *data)
 {
        struct comedi_bond_private *devpriv = dev->private;
-#define LSAMPL_BITS (sizeof(unsigned int)*8)
-       unsigned nchans = LSAMPL_BITS, num_done = 0, i;
+       unsigned int n_left, n_done, base_chan;
+       unsigned int write_mask, data_bits;
+       struct bonded_device **devs;
 
-       if (devpriv->nchans < nchans)
-               nchans = devpriv->nchans;
+       write_mask = data[0];
+       data_bits = data[1];
+       base_chan = CR_CHAN(insn->chanspec);
+       /* do a maximum of 32 channels, starting from base_chan. */
+       n_left = devpriv->nchans - base_chan;
+       if (n_left > 32)
+               n_left = 32;
 
-       /*
-        * The insn data is a mask in data[0] and the new data
-        * in data[1], each channel cooresponding to a bit.
-        */
-       for (i = 0; num_done < nchans && i < devpriv->ndevs; ++i) {
-               struct bonded_device *bdev = devpriv->devs[i];
-               /*
-                * Grab the channel mask and data of only the bits corresponding
-                * to this subdevice.. need to shift them to zero position of
-                * course.
-                */
-               /* Bits corresponding to this subdev. */
-               unsigned int subdev_mask = ((1 << bdev->nchans) - 1);
-               unsigned int write_mask, data_bits;
-
-               /* Argh, we have >= LSAMPL_BITS chans.. take all bits */
-               if (bdev->nchans >= LSAMPL_BITS)
-                       subdev_mask = (unsigned int)(-1);
-
-               write_mask = (data[0] >> num_done) & subdev_mask;
-               data_bits = (data[1] >> num_done) & subdev_mask;
-
-               /* Read/Write the new digital lines */
-               if (comedi_dio_bitfield(bdev->dev, bdev->subdev, write_mask,
-                                       &data_bits) != 2)
-                       return -EINVAL;
+       n_done = 0;
+       devs = devpriv->devs;
+       do {
+               struct bonded_device *bdev = *devs++;
 
-               /* Make room for the new bits in data[1], the return value */
-               data[1] &= ~(subdev_mask << num_done);
-               /* Put the bits in the return value */
-               data[1] |= (data_bits & subdev_mask) << num_done;
-               /* Save the new bits to the saved state.. */
-               s->state = data[1];
+               if (base_chan < bdev->nchans) {
+                       /* base channel falls within bonded device */
+                       unsigned int b_chans, b_mask, b_write_mask, b_data_bits;
+                       int ret;
 
-               num_done += bdev->nchans;
-       }
+                       /*
+                        * Get num channels to do for bonded device and set
+                        * up mask and data bits for bonded device.
+                        */
+                       b_chans = bdev->nchans - base_chan;
+                       if (b_chans > n_left)
+                               b_chans = n_left;
+                       b_mask = (1U << b_chans) - 1;
+                       b_write_mask = (write_mask >> n_done) & b_mask;
+                       b_data_bits = (data_bits >> n_done) & b_mask;
+                       /* Read/Write the new digital lines. */
+                       ret = comedi_dio_bitfield2(bdev->dev, bdev->subdev,
+                                                  b_write_mask, &b_data_bits,
+                                                  base_chan);
+                       if (ret < 0)
+                               return ret;
+                       /* Place read bits into data[1]. */
+                       data[1] &= ~(b_mask << n_done);
+                       data[1] |= (b_data_bits & b_mask) << n_done;
+                       /*
+                        * Set up for following bonded device (if still have
+                        * channels to read/write).
+                        */
+                       base_chan = 0;
+                       n_done += b_chans;
+                       n_left -= b_chans;
+               } else {
+                       /* Skip bonded devices before base channel. */
+                       base_chan -= bdev->nchans;
+               }
+       } while (n_left);
 
        return insn->n;
 }

diff --git a/drivers/staging/comedi/kcomedilib/kcomedilib_main.c b/drivers/staging/comedi/kcomedilib/kcomedilib_main.c
index c7e809b35fd256febb0ec0db3f0c478b5922cef8..cd60677a3ed2f2771120dc5d23597e82a6fd34f9 100644 (file)
--- a/drivers/staging/comedi/kcomedilib/kcomedilib_main.c
+++ b/drivers/staging/comedi/kcomedilib/kcomedilib_main.c
@@ -159,28 +159,53 @@ int comedi_dio_config(struct comedi_device *dev, unsigned int subdev,
 }
 EXPORT_SYMBOL_GPL(comedi_dio_config);
 
-int comedi_dio_bitfield(struct comedi_device *dev, unsigned int subdev,
-                       unsigned int mask, unsigned int *bits)
+int comedi_dio_bitfield2(struct comedi_device *dev, unsigned int subdev,
+                        unsigned int mask, unsigned int *bits,
+                        unsigned int base_channel)
 {
        struct comedi_insn insn;
        unsigned int data[2];
+       unsigned int n_chan;
+       unsigned int shift;
        int ret;
 
+       if (subdev >= dev->n_subdevices)
+               return -EINVAL;
+
+       base_channel = CR_CHAN(base_channel);
+       n_chan = comedi_get_n_channels(dev, subdev);
+       if (base_channel >= n_chan)
+               return -EINVAL;
+
        memset(&insn, 0, sizeof(insn));
        insn.insn = INSN_BITS;
+       insn.chanspec = base_channel;
        insn.n = 2;
        insn.subdev = subdev;
 
        data[0] = mask;
        data[1] = *bits;
 
-       ret = comedi_do_insn(dev, &insn, data);
-
-       *bits = data[1];
+       /*
+        * Most drivers ignore the base channel in insn->chanspec.
+        * Fix this here if the subdevice has <= 32 channels.
+        */
+       if (n_chan <= 32) {
+               shift = base_channel;
+               if (shift) {
+                       insn.chanspec = 0;
+                       data[0] <<= shift;
+                       data[1] <<= shift;
+               }
+       } else {
+               shift = 0;
+       }
 
+       ret = comedi_do_insn(dev, &insn, data);
+       *bits = data[1] >> shift;
        return ret;
 }
-EXPORT_SYMBOL_GPL(comedi_dio_bitfield);
+EXPORT_SYMBOL_GPL(comedi_dio_bitfield2);
 
 int comedi_find_subdevice_by_type(struct comedi_device *dev, int type,
                                  unsigned int subd)